Digital PDFs

EK-DECB1-CG-A01

May 1993

292 pages

Original

0.8MB

Document:	DECbrouter 90 Products Configuration and Reference Volume 1
Order Number:	EK-DECB1-CG
Revision:	A01
Pages:	292
Original Filename:

OCR Text

DECbrouter 90 Products
Configuration and Reference
Volume 1
Order Number: EK–DECB1–CG. A01

First Edition, May 1993
The information in this document is subject to change without notice and should not be construed
as a commitment by Digital Equipment Corporation. Digital Equipment Corporation assumes no
responsibility for any errors that may appear in this document.
The software described in this document is furnished under a license and may be used or copied
only in accordance with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment that is not supplied
by Digital Equipment Corporation or its affiliated companies.
Restricted Rights: Use, duplication, or disclosure by the U.S. Government is subject to restrictions
as set forth in subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software
clause at DFARS 252.227-7013.
© Digital Equipment Corporation 1993.
FCC NOTICE: The equipment described in this manual generates, uses, and may emit radio
frequency energy. The equipment has been type tested and found to comply with the limits for
a Class A computing device pursuant to Subpart J of Part 15 of FCC Rules, which are designed
to provide reasonable protection against such radio frequency interference when operated in a
commercial environment. Operation of this equipment in a residential area may cause interference,
in which case the user at his own expense may be required to take measures to correct the
interference.
The following are trademarks of Digital Equipment Corporation: DEC, DECbrouter, DECnet, VAX,
VMS, and the Digital logo.
Apollo NCS is a trademark of Apollo Computer, Inc.
AppleTalk is a registered trademark of Apple Computer, Inc.
AT&T is a registered trademark of American Telephone and Telegraph.
IGRP, IGS, and Cisco are trademarks of Cisco Systems, Inc.
NetBios is a trademark of Micro Computer Systems, Inc.
Novelle IPX is a registered trademark of Novelle, Inc.
Sun Workstation is a registered trademark of Sun Microsystems, Inc.
SuperLAT is a trademark of Meridan Technology Corporation.
TYMNET is a registered trademark of McDonnell Douglas Corporation.
UNIX is a registered trademark of American Telephone and Telegraph.
VINES is a registered trademark of Banyan Systems, Inc.
All other trademarks and registered trademarks are the property of their respective holders.

This document was prepared using VAX DOCUMENT, Version 2.1.

Contents
About This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

xiii

Obtaining Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 Router Product Overview
Capabilities of the Router . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Support for Multiple Network Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dynamic Network Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Support for Standard Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1–1
1–1
1–2
1–2

2 First-Time Startup and Basic Configuration
Using the Setup Facility for Basic Configuration . . . . . . . . . . . . . . . . . . . . . . . . . .
Capabilities of the SETUP Command Facility . . . . . . . . . . . . . . . . . . . . . . . . .
Using the SETUP Command Facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
First-Time System Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sample Configuration Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the EXEC Command Interpreter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Command Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EXEC Command Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Entering Configuration Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Entering the Configuration Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Examples of Configuration Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Global Configuration Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interface Subcommands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Line Subcommands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Router Subcommands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Creating the Configuration File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring from the Console . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Writing the Configuration File to Nonvolatile Memory . . . . . . . . . . . . . . .
Writing the Configuration File to a Remote Host . . . . . . . . . . . . . . . . . . . .
Setting Up Auto Load of the Configuration File . . . . . . . . . . . . . . . . . . . . .
Using TFTP to Load Configuration Files or System Images . . . . . . . . . . . . . .
Loading Configuration Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using Flash Memory for Storing and Booting System Software . . . . . . . . . . . .
Reloading the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2–1
2–1
2–2
2–3
2–4
2–7
2–7
2–7
2–8
2–9
2–10
2–10
2–10
2–11
2–11
2–11
2–12
2–12
2–13
2–13
2–14
2–14
2–15
2–15

iii

3 Using Terminals
Making and Managing Terminal Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Making Telnet Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing Multiple Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Listing Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resuming a Previous Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Naming a Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exiting a Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disconnecting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resetting a Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Executing Special Telnet Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Incoming Telnet Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LAT EXEC Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying TCP Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Active Sessions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Information About Active Lines . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing Terminal Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the Terminal Screen Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the Terminal Screen Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the Terminal Escape Character . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying the Debug Messages on the Console and Terminals . . . . . . . . . . . .
Establishing Input Notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the Character Padding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Terminal Parameter Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Widths for International Character Sets at the User Level . . . . . . . . .
Using the Digital MOP Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EXEC Terminal Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3–1
3–1
3–2
3–2
3–3
3–3
3–3
3–4
3–4
3–4
3–5
3–5
3–5
3–6
3–6
3–6
3–7
3–7
3–7
3–8
3–8
3–8
3–9
3–9
3–10
3–11

4 Configuring the System
Configuring the Global System Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Host Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Banner Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying a Message-of-the-Day Banner . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying a Banner with an EXEC Process . . . . . . . . . . . . . . . . . . . . . . .
Displaying an Incoming Message Banner . . . . . . . . . . . . . . . . . . . . . . . . .
Order of Banner Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Default Widths for International Character Sets . . . . . . . . . . . . . . . . .
Setting the System Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dynamic Buffer Sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Configuration File Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the Network Configuration Filename . . . . . . . . . . . . . . . . . . . . .
Changing the Host Configuration Filename . . . . . . . . . . . . . . . . . . . . . . . .
Specifying a Boot File Buffer Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Multiple Instances of the Boot Commands . . . . . . . . . . . . . . .
Storing and Booting System Software Using the Flash Memory . . . . . . . . . . .
Security Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flash Memory Configuration Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .
Verifying Installation and Displaying Flash ROM Statistics . . . . . . . . . . .
Entering the Bootstrap Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Copying the TFTP Image to Flash Memory . . . . . . . . . . . . . . . . . . . . . . . .
Copying the MOP Image to Flash Memory . . . . . . . . . . . . . . . . . . . . . . . .
Automatically Booting from Flash Memory . . . . . . . . . . . . . . . . . . . . . . . .
Manually Booting from Flash Memory . . . . . . . . . . . . . . . . . . . . . . . . . . .
iv

4–1
4–1
4–2
4–2
4–3
4–3
4–3
4–4
4–5
4–5
4–6
4–6
4–7
4–7
4–7
4–8
4–8
4–8
4–9
4–10
4–13
4–15
4–16
4–17

Copying the Flash Memory Image to a TFTP Server . . . . . . . . . . . . . . . . .
Configuring Flash Memory as a TFTP Server . . . . . . . . . . . . . . . . . . . . . .
Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Flash Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing Passwords and System Security . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing the Privileged-Level Password . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying a Password . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recovering from a Lost Password . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Encrypting Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing Terminal Access Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Server Host Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Limiting Login Attempts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controlling Retries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Timeout Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Last Resort Login Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing Privileged-Level TACACS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling the Privileged Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling the Privileged Mode Last Resort Login Feature . . . . . . . . . . . . .
Configuring TACACS Accounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling Extended TACACS Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Login Notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Login Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optional Password Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Authenticating User Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Simple Network Management Protocol (SNMP) . . . . . . . . . . . . . .
Enabling and Disabling the SNMP Server . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defining the SNMP Server Access List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Community String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing the Message Queue Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing Packet Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing the TRAP Message Recipient . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing TRAP Message Authentication . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing the TRAP Message Timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling SNMP System Shutdown Feature . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Trivial File Transfer Protocol (TFTP) Server . . . . . . . . . . . . . . . .
Tailoring Use of Network Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Redirecting System Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling Message Logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logging Messages to an Internal Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logging Messages to the Console . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logging Messages to Another Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logging Messages to a UNIX Syslog Server . . . . . . . . . . . . . . . . . . . . . . . . . . .
Limiting Messages to a Syslog Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Console and Virtual Terminal Lines . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Line Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing Line Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Widths for International Character Sets for the Interface . . . . . . . . . .
Establishing Connection Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Suppressing Banner Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning On and Off the Vacant Banner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Escape Character . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Terminal Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the EXEC Timeout Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Screen Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4–17
4–18
4–18
4–18
4–19
4–19
4–20
4–21
4–21
4–22
4–22
4–23
4–23
4–23
4–24
4–24
4–24
4–25
4–25
4–25
4–26
4–26
4–26
4–27
4–28
4–28
4–28
4–29
4–29
4–30
4–30
4–31
4–31
4–32
4–32
4–33
4–33
4–34
4–34
4–34
4–35
4–36
4–36
4–37
4–37
4–38
4–38
4–39
4–40
4–40
4–41
4–41
4–42
4–42

Setting Notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Character Padding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Global System Configuration Command Summary . . . . . . . . . . . . . . . . . . . . . . . .
Line Configuration Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4–43
4–43
4–43
4–51

5 Using MOP
MOP Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring MOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling MOP for an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sending MOP System ID Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Network Configurator Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Retransmit Timer Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Maximum Number of Retransmissions . . . . . . . . . . . . . . . . . . . . . . . .
Copying a MOP Image to Flash Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Erasing Flash Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aborting the Copy Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote Router Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Debugging MOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5–1
5–2
5–2
5–2
5–3
5–3
5–4
5–4
5–6
5–8
5–8
5–9
5–10

6 Managing and Monitoring the System
Monitoring System Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Buffer Pool Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying System Memory Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Active System Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Memory Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Stack Utilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying the System Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying the Error Logging Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Protocol Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting Network Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Real-time Debugging Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing Connectivity with the PING Command . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Routes with the TRACE Command . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Writing System Configuration Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EXEC System Management Command Summary . . . . . . . . . . . . . . . . . . . . . . . . .

6–1
6–2
6–3
6–4
6–5
6–6
6–6
6–6
6–7
6–8
6–8
6–10
6–11
6–11
6–12
6–12

7 Configuring the Interfaces
Specifying an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding a Descriptive Name to an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutting Down and Restarting an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clearing Interface Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Information About an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying the System Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Controller Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Interface Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Serial Interface Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying a Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Serial Encapsulation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HDLC Serial Encapsulation Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7–1
7–2
7–2
7–3
7–3
7–3
7–4
7–6
7–7
7–7
7–8
7–9

Maintaining the Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring the Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Debugging the Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ethernet Interface Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying an Ethernet Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ethernet Encapsulation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintaining the Ethernet Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring the Ethernet Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Debugging the Ethernet Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Dial Backup Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Dial Backup Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defining the Traffic Load Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defining the Backup Line Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dial Backup Configuration Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Dial-on-Demand Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DECbrouter 90 DDR Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying Dialer Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controlling Dialer Idle Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Idle Time for Busy Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying Dialer Enable Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying Carrier Wait Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying a Single DDR Telephone Number . . . . . . . . . . . . . . . . . . . . . . . . . .
CCITT V.25bis Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Multiple Destinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying Multiple Destinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dialer Rotary Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assigning Access Lists to a DDR Interface . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using Access Lists with DDR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dial-on-Demand Access-List Configuration Examples . . . . . . . . . . . . . . . . . . .
Monitoring Dial-on-Demand Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Debugging Dial-on-Demand Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Point-to-Point Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Challenge Handshake Access Protocol (CHAP) . . . . . . . . . . . . . . . . . . . . . . . .
Enabling CHAP on the Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Host Name Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Null Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Global Configuration Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interface Support Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interface Support EXEC Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7–9
7–9
7–13
7–14
7–14
7–14
7–15
7–15
7–19
7–19
7–20
7–20
7–21
7–22
7–23
7–23
7–24
7–25
7–25
7–26
7–26
7–27
7–27
7–28
7–29
7–31
7–32
7–33
7–35
7–38
7–40
7–40
7–41
7–41
7–42
7–44
7–44
7–45
7–49

8 Adjusting Interface Characteristics
Adjusting Serial Interface Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying Transmit Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring DTR Signal Pulsing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjusting Characteristics That Apply to All Interface Types . . . . . . . . . . . . . . . . .
Configuring Switching and Scheduling Priorities . . . . . . . . . . . . . . . . . . . . . . .
Priority Output Queuing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assigning Priority by Protocol Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assigning Priority by Interface Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assigning a Default Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying the Maximum Packets in the Priority Queues . . . . . . . . . . . . .
Assigning a Priority Group to an Interface . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring the Priority Queuing Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8–1
8–1
8–1
8–2
8–2
8–2
8–3
8–6
8–6
8–6
8–7
8–7

vii

Assigning Priority by Serial Link Address . . . . . . . . . . . . . . . . . . . . . . . . .
Controlling Interface Hold Queues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting and Adjusting Packet Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling the Loopback Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling Loopback on the Serial Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling Loopback on the Ethernet Interface . . . . . . . . . . . . . . . . . . . . . . . . .
Global Configuration Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interface Configuration Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . .

8–8
8–8
8–9
8–10
8–10
8–11
8–11
8–11
8–12
8–13

9 Configuring Packet-Switched Software
Configuring LAPB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running a Single Network Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running Multiple Network Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sample Configuration of LAPB Encapsulation . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the X.25 Level 2 (LAPB) Parameters . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Retransmission Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Frame Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring and Troubleshooting LAPB . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring X.25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview of Digital X.25 Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transporting LAN Protocols Across an X.25 PDN . . . . . . . . . . . . . . . . . . . . . .
X.25 Encapsulation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Address Mapping Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Address Mappings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring X.25 to Allow Ping Support over Multiple Lines . . . . . . . . . . .
Setting Encapsulation Permanent Virtual Circuits . . . . . . . . . . . . . . . . . .
Protocol-to-Virtual Circuit Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Address Mappings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example X.25 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Routing X.25 Traffic through a LAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling X.25 Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Constructing the X.25 Routing Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Translating X.25 Called Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Switched PVCs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
X.25 Switching Configuration Examples . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the X.25 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the X.25 Interface Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Virtual Circuit Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Lowest Incoming-only Circuit Number . . . . . . . . . . . . . . . . . .
Setting the Highest Incoming-only Circuit Number . . . . . . . . . . . . . . . . . .
Setting the Lowest Two-way Circuit Number . . . . . . . . . . . . . . . . . . . . . . .
Setting the Highest Two-way Circuit Number . . . . . . . . . . . . . . . . . . . . . .
Setting the Lowest Outgoing-only Circuit Number . . . . . . . . . . . . . . . . . .
Setting the Highest Outgoing-only Circuit Number . . . . . . . . . . . . . . . . . .
Maintaining Virtual Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Ignore VC Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the X.25 Level 3 Retransmission Timers . . . . . . . . . . . . . . . .
Setting the DTE Restart Request Retransmission Timer . . . . . . . . . . . . . .
Setting the DCE Restart Request Retransmission Timer . . . . . . . . . . . . . .
Setting the DTE Call Request Limit Timer . . . . . . . . . . . . . . . . . . . . . . . .
Setting the DCE Call Request Limit Timer . . . . . . . . . . . . . . . . . . . . . . . .

viii

9–1
9–2
9–2
9–2
9–2
9–3
9–3
9–4
9–5
9–6
9–7
9–7
9–8
9–8
9–10
9–11
9–13
9–14
9–16
9–18
9–19
9–19
9–20
9–21
9–22
9–23
9–23
9–24
9–25
9–25
9–25
9–25
9–25
9–26
9–26
9–27
9–27
9–27
9–27
9–28
9–28

Setting the DTE Reset Request Retransmission Timer . . . . . . . . . . . . . . .
Setting the DCE Reset Request Retransmission Timer . . . . . . . . . . . . . . .
Setting the DTE Clear Request Retransmission Timer . . . . . . . . . . . . . . .
Setting the DCE Clear Request Retransmission Timer . . . . . . . . . . . . . . .
Updating the X.121 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting X.25 Packet Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Flow Control Modulus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Packet Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Suppressing the Calling Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Suppressing the Called Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defining a Packet Hold Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accepting Reverse-Charged Calls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Forcing Packet-Level Restarts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Packet Network Carrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting X.25 Parameters on a Per-Call Basis . . . . . . . . . . . . . . . . . . . . . . .
X.25 TCP Header Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bridging on X.25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Datagram Transport on DDN Networks . . . . . . . . . . . . . . . . . . . .
Enabling DDN X.25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blacker Emergency Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BFE Device Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Router Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring Blacker Emergency Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DDN X.25 Dynamic Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DDN X.25 Configuration Subcommands . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintaining X.25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring X.25 Level 3 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Interface Parameters and Statistics . . . . . . . . . . . . . . . . . . . . .
Displaying General Virtual Circuit Parameters and Statistics . . . . . . . . . .
Debugging X.25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring CMNS Routing Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling CMNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying CMNS Address Mappings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CMNS Configuration Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring CMNS Traffic Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring CMNS with LLC2 Parameters . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying CMNS Virtual Circuit Parameters and Statistics . . . . . . . . . . .
Debugging CMNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Frame Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying Frame Relay Encapsulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling ANSI Frame Relay LMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the Frame Relay Keepalive Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mapping Between an Address and the DLCI . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring for ISO CLNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Requesting Short Status Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting a Local DLCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defining a DLCI for Multicast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frame Relay Configuration Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Two Routers in Static Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Routing DECnet Packets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Routing Novell Packets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9–28
9–28
9–28
9–28
9–29
9–29
9–29
9–30
9–31
9–31
9–31
9–31
9–32
9–32
9–32
9–33
9–34
9–34
9–34
9–35
9–35
9–35
9–37
9–37
9–39
9–39
9–39
9–39
9–40
9–41
9–42
9–43
9–43
9–44
9–48
9–49
9–50
9–51
9–51
9–52
9–53
9–53
9–54
9–54
9–55
9–56
9–56
9–57
9–57
9–57
9–58
9–58

Monitoring Frame Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring the Frame Relay Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring ANSI Frame Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Frame Relay Map Entries . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Global Frame Relay Statistics . . . . . . . . . . . . . . . . . . . . . . . . .
Debugging Frame Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Switched Multimegabit Data Services (SMDS) . . . . . . . . . . . . . . . . . .
Special SMDS Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring SMDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using SMDS Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling SMDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifying the SMDS Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling the Address Resolution Protocol . . . . . . . . . . . . . . . . . . . . . . . . .
Defining a Static Map for an Individual Address . . . . . . . . . . . . . . . . . . . .
Mapping to a Multicast Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enabling the AT&T SMDS Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Specific Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring AppleTalk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring XNS and Novell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring CLNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IP Fast Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring Fast Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Debugging Fast Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMDS Configuration Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical Multiprotocol Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration with a Remote Peer on the Same Network . . . . . . . . . . . . .
Monitoring SMDS Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying SMDS Individual Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying Mapped SMDS Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying SMDS Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Debugging SMDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Packet-Switched Software Global Configuration Command Summary . . . . . . . . . .
X.25 Global Configuration Command Summary . . . . . . . . . . . . . . . . . . . . . . . .
Packet-Switched Software Interface Subcommand Summary . . . . . . . . . . . . . . . . .
CMNS Interface Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frame Relay Interface Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . .
LAPB Interface Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SMDS Interface Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
X.25 Interface Subcommand Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
X.25 EXEC Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9–58
9–58
9–59
9–60
9–60
9–61
9–61
9–62
9–62
9–63
9–63
9–64
9–64
9–65
9–65
9–66
9–66
9–67
9–67
9–67
9–68
9–68
9–68
9–68
9–68
9–68
9–69
9–70
9–70
9–70
9–70
9–71
9–71
9–71
9–73
9–73
9–74
9–75
9–76
9–77
9–86

Index
Figures
7–1
7–2
7–3
9–1
9–2
9–3

Dial-on-Demand Interconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hub-and-Spoke Environment Using Dial-on-Demand . . . . . . . . . . . . .
Dial-on-Demand Routing Configuration . . . . . . . . . . . . . . . . . . . . . . . .
Transporting LAN Protocols Across an X.25 PDN . . . . . . . . . . . . . . . .
Routing X.25 Traffic Through a LAN . . . . . . . . . . . . . . . . . . . . . . . . . .
Communicating via Routers Through an X.25 Network . . . . . . . . . . . .

7–24
7–29
7–44
9–6
9–7
9–8

9–4
9–5
9–6
9–7
9–8
9–9
9–10

Parallel Serial Lines to X.25 Network . . . . . . . . . . . . . . . . . . . . . . . . .
Establishing a PVC through an X.25 Network . . . . . . . . . . . . . . . . . . .
X.121 Address Translation Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . .
DDN Internet/X.121 Address Conventions . . . . . . . . . . . . . . . . . . . . . .
Example Network Topology for Switching CMNS over a PDN . . . . . . .
Example Network Topology for Switching CMNS over a Leased Line
.......................................................
Frame Relay Physical Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9–10
9–13
9–21
9–38
9–45

Configuration Edit Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Commands in the Digital Systems Telnet Implementation . . .
Show Flash Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Show Flash All Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logging Message Keywords and Levels . . . . . . . . . . . . . . . . . . . . . . . .
Show Buffers Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Show Memory Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Characteristics of Each Block of Memory . . . . . . . . . . . . . . . . . . . . . . .
Show Processes Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Show Processes Memory Field Descriptions . . . . . . . . . . . . . . . . . . . . .
Show Logging Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Per-Packet Counted Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Show Interfaces Serial Field Descriptions . . . . . . . . . . . . . . . . . . . . . .
Show Interfaces Ethernet Field Descriptions . . . . . . . . . . . . . . . . . . . .
CCITT V.25bis Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common TCP Services and Their Port Numbers . . . . . . . . . . . . . . . . .
Common UDP Services and Their Port Numbers . . . . . . . . . . . . . . . . .
Default Media MTU Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LAPB Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Protocols and Initial Byte of Call User Data . . . . . . . . . . . . . . . . . . . .
Show X25 Map Field Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pattern Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Character Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Range Limit Keywords for the Switched Virtual Circuit Ranges . . . . .
Retransmission Timer Keywords and Defaults . . . . . . . . . . . . . . . . . .
Protocol Families and Types of Multicasts Needed . . . . . . . . . . . . . . . .

2–9
3–4
4–9
4–10
4–35
6–3
6–4
6–4
6–5
6–6
6–7
7–7
7–11
7–16
7–28
8–4
8–4
8–10
9–3
9–14
9–15
9–20
9–21
9–25
9–27
9–67

9–47
9–52

Tables
2–1
3–1
4–1
4–2
4–3
6–1
6–2
6–3
6–4
6–5
6–6
7–1
7–2
7–3
7–4
8–1
8–2
8–3
9–1
9–2
9–3
9–4
9–5
9–6
9–7
9–8

About This Guide
This section discusses the objectives, audience, organization, and conventions of
this guide. It also lists related Digital publications.

Audience
This publication is intended for system administrators who will configure and
maintain a DECbrouter 90.

Organization
The following chapters are contained in this guide:
•

Chapter 1, Router Product Overview–contains an overview of the
DECbrouter 90, including router capabilities, network protocols supported by
the DECbrouter 90, routing protocols supported by the DECbrouter 90, and
the media supported by the DECbrouter 90.

•

Chapter 2, First-Time Startup and Basic Configuration–describes basic
system startup procedures and use.

•

Chapter 3, Using Terminals–describes use of physical and virtual terminals
on the DECbrouter 90 product including, making Telnet server connections
from a console attached to the router/bridge, making local changes to the
terminal parameters, and using the Digital MOP terminal server.

•

Chapter 4, Configuring the System–describes how to configure the system
including, setting global system characteristics, defining the size of the
system buffers, changing the system boot file specifications, storing and
booting system software images with flash memory, establishing system and
line passwords and system secruity, defining networking services, enabling
and directing the logging of system debugging messages, and configuring the
console and virtual terminal lines.

•

Chapter 5, Using MOP–describes how to use the maintenance operating
protocol (MOP).

•

Chapter 6, Managing and Monitoring the System–describes the EXEC
commands you use to monitor, manage, and troubleshoot general system
processes and conditions on your DECbrouter 90.

•

Chapter 7, Configuring the Interfaces–describes how to enable, shut
down, and display messages pertinent to interface configuration and
operation. This chapter also describes the procedures for configuring and
maintaining the serial and Ethernet interfaces.

xiii

•

Chapter 8, Adjusting Interface Characteristics–describes how to make
adjustments to the router interfaces and how to enable loopback tests.

•

Chapter 9, Configuring Packet-Switched Software–describes the
configuration tasks for packet-switched software, including Recommendation
X.25, CMNS support, Frame relay service, and SMDS.

Conventions
The following conventions are used in this guide:
Convention

Meaning

system displays

Terminal sessions and information the system displays are
printed in monospace type.

boldface

Information you enter is in boldface type. Keywords are also in
boldface type.

Nonprinting characters are shown in angle brackets.

[]

Defaults are in square brackets.

COMMANDS

Commands are in uppercase letters.

italics

Command variables, worksheet values, new terms and
concepts, and titles of books and periodicals are in italics.

Ctrl/X

Indicates two keys that you must press simultaneously.

Note

Provides general information about the current topic.

Caution

Provides information to prevent damage to equipment.

Related Documentation
The most important companion to this guide is the set of Digital documentation
that accompanies the product. This guide refers you to the appropriate manual
for additional reference material that is beyond the scope of this guide. The
following manuals are shipped with the DECbrouter 90:
•

DECbrouter 90 Products Getting Started

•

DECbrouter 90 Products Configuration and Reference, Volume 2

•

DECbrouter 90 Products Configuration and Reference, Volume 3

•

DECbrouter 90T Installation and Operating Information

•

DECbrouter 90 System Error Messages

•

DECbrouter 90 Products Command Summary

To order these publications or additional copies of this guide, contact your sales
representative. Refer to the How to Order Additional Documentation page at the
back of this document for addresses and phone numbers.

Service and Support
Call your local representative for service.

xiv

Obtaining Additional Information
This section describes how to obtain additional Digital publications and includes
tips for obtaining books, standards, and other information about networks and
data communications that might be helpful while using Digital products.

Ordering Additional Digital Publications
To order these publications or additional copies of the DECbrouter 90 Products
Configuration and Reference guides, contact your local representative.

Obtaining Information
This section describes how to obtain RFCs and technical standards.

Obtaining RFCs
Information about the Internet suite of protocols is contained in documents
called Requests for Comments or RFCs. These documents are maintained by
Government Systems, Inc. (GSI). You can request copies by contacting GSI
directly, or you can use the TCP/IP File Transfer Protocol (FTP) to obtain an
electronic copy.
Contacting GSI
You can contact GSI through mail, by telephone, or through electronic mail:
Government Systems, Incorporated
Attn: Network Information Center
14200 Park Meadow Drive, Suite 200
Chantilly, Virginia 22021
1-800-365-3642
(703) 802-4535
(703) 802-8376 (FAX)
NIC@NIC.DDN.MIL
Network address: 192.112.36.5
Root domain server: 192.112.36.4
Obtaining an Electronic Copy
To obtain an electronic copy of an RFC through FTP, complete the following steps:
1. At your server prompt, use the ftp command to connect to address
nic.ddn.mil:
% ftp nic.ddn.mil

The following display appears, followed by a login prompt:
Connected to nic.ddn.mil.
220-*****Welcome to the Network Information Center*****
*****Login with username "anonymous" and password "guest"
*****You may change directories to the following:
ddn-news
- DDN Management Bulletins
domain
- Root Domain Zone Files
ien
- Internet Engineering Notes
iesg
- IETF Steering Group
ietf
- Internet Engineering Task Force
internet-drafts - Internet Drafts
netinfo
- NIC Information Files
netprog
- Guest Software (ex. whois.c)
protocols
- TCP-IP & OSI Documents
rfc
- RFC Repository
scc
- DDN Security Bulletins
220 And more.
2. At the login prompt, enter the word anonymous as your login name:
Name (nic.ddn.mil:cindy): anonymous
The NIC responds with this message:
331 Guest login ok, send "guest" as password.
Password:
3. Enter the word guest at the Password: prompt. The following message and
ftp> prompt appear:
230 Guest login ok, access restrictions apply.
ftp>
4. Use the cd command to change directories. The following example illustrates
how to change the RFC directory and obtain RFC 1158:
ftp> cd rfc
250 CWD command successful.
ftp> get rfc1158.txt
5. To exit the FTP facility, enter the quit command at the ftp> prompt.

Obtaining Technical Standards
Following are additional sources for technical standards:

xvi

•

Omnicom, 1-800-OMNICOM

•

Global Engineering Documents, 2805 McGraw Ave., Irvine, CA 92714
1-800-854-7179

•

American National Standards Institute, 1430 Broadway, New York, NY 10018
(212) 642-4932 or (212) 302-1286

1
Router Product Overview
This chapter provides a product overview of the DECbrouter 90, including:
•

Router capabilities

•

Network protocols supported by the DECbrouter 90

•

Routing protocols supported by the DECbrouter 90

•

Media supported by the DECbrouter 90

Capabilities of the Router
Complex internetworks have grown past the point where they can depend on
equipment from a single vendor. Virtually all organizations connecting local area
networks and creating wide area networks today have major commitments to
hardware and software from many different vendors. Therefore, current and
future internetworking requires products that support multiprotocol, multimedia,
and multivendor networks.
The DECbrouter 90 helps LANs and WANs achieve interoperability and
connectivity. This section describes Digital-supported protocols and media, as
well as the capabilities of the DECbrouter 90 for routing, network management,
and network security.

Support for Multiple Network Protocols
Large organizations need the flexibility that multiprotocol networks give them
to communicate with diverse hardware and software from many vendors. The
DECbrouter 90 supports many networking protocols, as well as several specific
routing protocols for compatibility with other networks. Included are protocols
based on open standards and proprietary protocols from a variety of vendors.
The DECbrouter 90 can forward packets concurrently from any combination of
the following networking protocols:
•

TCP/IP

•

DECnet Phase IV

•

Xerox Network Service (XNS)

•

Novell IPX

•

Ungermann-Bass

•

AppleTalk (Phase 1 and Phase 2)

•

ISO Connectionless Network Services (CLNS) and Connection Mode Network
Services (CMNS)

•

Apollo Domain

•

Banyan VINES

Router Product Overview 1–1

Router Product Overview
Capabilities of the Router
•

Xerox’s Universal Protocol (PUP)

•

CHAOSnet

•

X.25 protocols

•

DDN protocols, as used with the DDN X.25 Standard, 1822-LH/DH, and HDH
(1822-J) attachments

•

Frame Relay serial encapsulation

•

Switched Multimegabit Data Service (SMDS) protocol

•

Point-to-Point Protocol (PPP)

Dynamic Network Routing
The Interior Gateway Routing Protocol (IGRP), developed by Cisco Systems
for TCP/IP and ISO CLNS (referred to as ISO-IGRP), monitors the network to
determine the status of each route and selects the best route for each data packet.
Network traffic, path reliability, and path speed all influence route selection.
While running IGRP or ISO-IGRP, the DECbrouter 90 can concurrently receive
and understand messages from other network segments sent using different
routing protocols. For example, IP routing protocols supported by the DECbrouter
90, in addition to IGRP, include:
•

Open Shortest Path First (OSPF)—the link state-based interior gateway
protocol defined by RFC 1247.

•

Routing Information Protocol (RIP)—the interior routing protocol used by the
routing process on Berkeley-derived UNIX systems.

•

Exterior Gateway Protocol (EGP)—the routing protocol used by all routers
attached to the Defense Data Network (DDN). This implementation maintains
contact with multiple EGP-speaking routers, preserving routing information
when the DDN core routers do not respond.

•

Border Gateway Protocol (BGP) is a replacement protocol for EGP. BGP is
defined by RFC 1163.

Similarly, the DECbrouter 90 supports concurrent operation of ISO-IGRP and the
ISO-standard intermediate system-to-intermediate system (IS-IS).
The DECbrouter 90 router supports the native dynamic routing protocols used
by the various supported network protocols, such as DECnet, Novell IPX, and
AppleTalk. This allows compatibility with other vendor’s routers. Multiple
network protocols and their dynamic routing protocols operate concurrently,
sharing the same router and media.

Support for Standard Media
For convenient access to existing networks, The DECbrouter 90 supports these
industry-standard networking media:
•

Ethernet—IEEE 802.3 and Type II

•

Synchronous serial—V.10, V.11, V.28, V.35, (V.24)RS-232, RS-449, X.21,
EIA-422, EIA-423, and EIA-530A.

1–2 Router Product Overview

2
First-Time Startup and Basic Configuration
This chapter describes basic system startup and use. Information in this chapter
will help you with these tasks:
•

First-time startup and basic configuration of the DECbrouter 90 using the
SETUP command facility

•

Understanding and using the system’s command interpreter

•

Entering configuration commands into a configuration file and saving the
configuration

•

Using TFTP to load configuration files and system software images over the
network

•

Using the flash memory to boot and store system software images

•

Reloading the operating system

Using the Setup Facility for Basic Configuration
The SETUP command facility enables you to start using your network quickly
and without extensive background knowledge. It does this by prompting you for
the information required to perform basic configuration procedures.
Use the SETUP command facility both at initial system configuration and for
basic changes at any time. In addition, use the facility as a teaching tool to
become familiar with the expected command sequence as you step through the
process. Because of these additional characteristics, this manual refers to SETUP
as a command facility rather than simply as a command.
Refer to the DECbrouter 90 Products Getting Started publication for detailed
information and a step-by-step description of the configuration procedure using
the SETUP command facility.

Capabilities of the SETUP Command Facility
Use the SETUP command facility to do the following:
•

Establish host names

•

Set enable (or privileged mode) passwords

•

Set virtual terminal passwords

•

Enable SNMP network management

•

Enable routing of protocols

•

Enable transparent Ethernet bridging

First-Time Startup and Basic Configuration 2–1

First-Time Startup and Basic Configuration
Using the Setup Facility for Basic Configuration
Configure the following protocols with the SETUP command facility:
•

IP, including IGRP and RIP dynamic routing

•

DECnet (Phase IV)

•

XNS

•

Novell IPX

•

Appletalk Phase 1 and Phase 2

•

CLNS

•

VINES

For more advanced applications, you need to enter a privileged configuration
session, as described in the section Entering Configuration Mode later in this
chapter.

Using the SETUP Command Facility
The SETUP command facility operates automatically the first time you power
on your router and when you add new hardware components. To use SETUP
on subsequent occasions, you must invoke it as you would any other command
by entering SETUP at the EXEC prompt (described in the section Entering
Configuration Mode later in this chapter).
Before you start using the SETUP command facility, you need to do the following:
1. Attach an RS-232 ASCII terminal to the system console port located at the
bottom, front of the router.
Refer to the appropriate hardware installation and maintenance publications
for details about cabling considerations and establishing electrical
connections.
2. Configure the terminal to operate at 9600 baud, 8 data bits, no parity, 1 stop
bit.
3. Power on the router and run the setup program.
Note
Network connections are not required in order to effectively use the
SETUP command facility.

In addition, you need to know the following before you start:
•

Which protocols you plan to route.
Note that most protocols will prompt you for specific parameters, including
host name, network numbers, addresses, and subnet masks (when applicable).

•

Types of interfaces installed: Ethernet or Serial.

•

Whether or not you plan to use bridging.

2–2 First-Time Startup and Basic Configuration

First-Time Startup and Basic Configuration
Using the Setup Facility for Basic Configuration
First-Time System Startup
The SETUP command facility determines which interfaces are installed and
prompts you for configuration information for each one. Once you complete one
interface, the facility automatically starts over for the next, continuing until each
interface has been configured.

Note
Once you start the SETUP facility, the system runs through the entire
configuration process; you cannot quit out of it. If you want to make a
change or correct a mistake, simply press the Return key at each prompt,
then restart the command.

When you first power on your console and router, a script similar to the following
will appear on the screen. The first section of the script displays the banner
information, including the software version:
Restricted Rights Legend
Use, duplication, or disclosure by the Government is
subject to restrictions as set forth in subparagraph
(c) of the Commercial Computer Software - Restricted
Rights clause at FAR sec. 52.227-19 and subparagraph
(c) (1) (ii) of the Rights in Technical Data and Computer
Software clause at DFARS sec. 252.227-7013.
Cisco Systems, Inc.
1525 O’Brien Drive
Menlo Park, California 94025
3000 Software (IGS3-BFPX), Beta Version 9.14(0.17)
Copyright (c) 1986-1993 by Cisco Systems, Inc.
Compiled Fri 31-Jul-92 13:31
The next portion of the display is a list of the installed hardware. By reading the
installed hardware, the system automatically presents the appropriate interfaces
during the configuration process.
(68020) processor with 4096K bytes of memory.
X.25 software.
Bridging software.
1 Ethernet/IEEE 802.3 interface.
1 Serial network interface.
64 Kbytes of non-volatile memory.
The first two sections of the configuration script (the banner and the installed
hardware) appear each time the system is started up.
At the first-time system startup, the System Configuration Dialog automatically
appears, offering the prompts for which you’ll provide the answers to configure
your system.
--- System Configuration Dialog --At any point you may enter a question mark ’?’ for help.
Refer to the ’Getting Started’ Guide for additional help.
Default settings are in square brackets ’[]’. Continue with
configuration dialog? [yes]:

First-Time Startup and Basic Configuration 2–3

First-Time Startup and Basic Configuration
Using the Setup Facility for Basic Configuration
At this point, you may choose not to continue with the System Configuration
Dialog and exit by answering "no" to this prompt.
Answer "yes" to continue with the SETUP configuration dialog. The remainder
of the script is the actual configuration process, with each prompt appearing
automatically. Press the Return key to accept the default settings.
There is no default for the final prompt which asks you if you want to use this
configuration; you must answer either "yes" or "no." Also note that the SETUP
command only asks you to configure the protocols for each interface that you
specified on a global basis. For instance, if you said "no" for XNS under the global
parameters, the command does not prompt you to configure that protocol under
the interface parameters.
Sample Configuration Session
Configuring global parameters:
Enter host name [Router]: sandbox
Enter enable password: shovel
Enter virtual terminal password: pail
Configure SNMP Network Management? [no]: yes
Configure XRemote font servers? [no]: yes
Enter a font server IP address or press RETURN to exit:
121.78.1.1
Enter a font server IP address or press RETURN to exit:
Configure IP? [yes]:
Configure IGRP routing? [yes]:
Your IGRP autonomous system number [1]:
Configure DECnet? [no]: yes
Your area number [1]:
Your node number [1]:
Area (level 2) routing? [no]: yes
Configure XNS? [no]: yes
Configure Novell? [no]: yes
Configure AppleTalk? [no]: yes
Multizone networks? [no]: yes
Configure CLNS? [yes]:
CLNS router tag [area_1]:
CLNS domain [49]:
CLNS area [0001]:
CLNS station id [0000.0C01.0D1D]:
Configure Vines? [no]: yes
Configure bridging? [no]: yes
Configure LAT? [no]: yes

2–4 First-Time Startup and Basic Configuration

First-Time Startup and Basic Configuration
Using the Setup Facility for Basic Configuration
Configuring interface parameters:
Configuring interface Ethernet0:
Is this interface in use? [yes]:
Configure IP on this interface? [yes]:
IP address for this interface: 131.108.6.67
Number of bits in subnet field [0]:
Class B network is 131.108.0.0, 0 subnet bits; mask is 255.255.0.0
Configure DECnet on this interface? [yes]:
DECnet cost [10]:
Configure XNS on this interface? [yes]:
XNS network number [2]:
Configure Novell on this interface? [yes]:
Novell network number [2]:
Configure AppleTalk on this interface? [yes]:
Extended AppleTalk network? [no]: yes
AppleTalk starting cable range [4172]:
AppleTalk ending cable range [4172]:
AppleTalk zone name [twilight]:
AppleTalk zone name [ozone]:
AppleTalk zone name:
Configure CLNS on this interface? [yes]:
Configure Vines on this interface? [yes]:
Configure bridging on this interface? [yes]:
Configuring interface Serial0:
Is this interface in use? [yes]:
Configure IP on this interface? [yes]:
IP address for this interface: 131.108.97.67
Number of bits in subnet field [0]:
Class B network is 131.108.0.0, 0 subnet bits; mask is 255.255.0.0
Configure DECnet on this interface? [yes]: no
Configure XNS on this interface? [yes]: no
Configure Novell on this interface? [yes]: no
Configure AppleTalk on this interface? [yes]:
Extended AppleTalk network? [no]:
AppleTalk network number [1]:
AppleTalk zone name [twilight]:
Configure CLNS on this interface? [yes]:
Configure Vines on this interface? [yes]:
Configure bridging on this interface? [yes]:

First-Time Startup and Basic Configuration 2–5

First-Time Startup and Basic Configuration
Using the Setup Facility for Basic Configuration
The following configuration command script was created:
hostname sandbox
enable-password shovel
line vty 0 4
password pail
snmp-server community
xremote tftp host 121.78.1.1
!
ip routing
decnet routing 1.1
decnet node-type area
xns routing
novell routing
appletalk routing
clns routing
router iso-igrp area_1
net 49.0001.0000.0C01.0D1D.00
vines routing
bridge 1 protocol dec
!
!
!
!
interface Ethernet0
ip address 131.108.6.67 255.255.255.0
xns network 2
novell network 2
appletalk cable-range 4172-4172
appletalk discovery
clns router iso-igrp area_1
vines metric
bridge-group 1
!
interface Serial0
no shutdown
no ip address
appletalk address 50000.72
appletalk zone twilight
clns router iso-igrp area_1
vines metric
bridge-group 1
!
!
router igrp 109
network 131.108.0.0
!
end
Use this configuration? [yes/no]: yes
[OK]
Use the enabled mode ’configure’ command to modify this configuration.
Press RETURN to get started!
The server displays the system name (sandbox), followed by an angle bracket (>),
which is the prompt of the system’s command interpreter.

2–6 First-Time Startup and Basic Configuration

First-Time Startup and Basic Configuration
Using the EXEC Command Interpreter

Using the EXEC Command Interpreter
The command interpreter is called the EXEC. The EXEC interprets the
commands you type and carries out the corresponding operations.
You can type commands when you see the system prompt, which is the system’s
host name ending with an angle bracket (>). Although the default system host
name is Router>, this may have been changed during the initial configuration
using the SETUP command, or with the HOSTNAME configuration command.
The following sections describe how to use the EXEC.

Command Syntax
The EXEC accepts commands typed in uppercase letters, lowercase letters, or
both. You may also abbreviate commands and other keywords to the number of
characters that cause the command to be a unique abbreviation. For example,
you can abbreviate the SHOW command to SH.
If you make a typing mistake, you can erase characters one at a time with the
Delete or the Backspace key. Press either key to erase the last character typed.
To erase the entire line, enter Ctrl/U. (This notation means "Hold down the Ctrl
key and press the U key.") The server acts on most commands after you press the
Return key.
You can list available EXEC commands by typing a question mark (?). You
also can enter a question mark to obtain more information about commands.
For example, enter TERMINAL ? to obtain a list of TERMINAL commands or
SHOW ? to obtain a list of SHOW commands.
Certain EXEC commands produce multiple screens of output. At the end of each
screen, the EXEC pauses and displays:
-MoreType a space to continue the output; type anything else to return to the system
command prompt.

EXEC Command Levels
For security purposes, the EXEC has two levels of access: user and privileged.
The commands available at the user level are a subset of the commands available
at the privileged level. Because many of the privileged commands set operating
parameters, the privileged level should be password-protected to prevent its
unauthorized use. The system prompt for the privileged level ends with a pound
sign (#) instead of an angle bracket (>).
The EXEC ENABLE command allows access to the privileged level, prompting
for a password if one has been set with the ENABLE-PASSWORD configuration
command. (For more information, see the section Establishing Passwords and
System Security in Chapter 4.)
Enter a question mark ? to see a list of the user-level EXEC commands similar to
the following:

First-Time Startup and Basic Configuration 2–7

First-Time Startup and Basic Configuration
Using the EXEC Command Interpreter
Router> ?
connect <host> Connect to host - same as typing just a host name
disconnect <cn> Break the connection specified by name or number
exit, quit
Exit from the EXEC
name-connection Give a connection a logical name
resume
Make the named connection be current
show <cmd>
Information commands, enter "show ?" for list
systat
Show terminal lines and users
telnet <host> Connect to host using telnet protocol
terminal
Change terminal’s parameters, enter "terminal ?"
where
Show open connections
<cr>
To resume connection
Enter enable and then the password to access the privileged command level.
Enter the question mark ? to see a list of privileged-level EXEC commands
similar to this example:
Router# ?
bfe
For manual emergency modes setting, enter "bfe?" for list
clear
Reinitialization functions, enter "clear ?" for list
configure
Configure from terminal or over network
connect <host> Connect to host - same as typing just a host name
debug
Enable debugging functions, enter "debug ?" for list
disable
Turn off privileged commands
disconnect <cn> Break the connection specified by name or number
enable
Turn on privileged commands
exit, quit
Exit from the EXEC
lat <service> Connect to service using DEC LAT protocol
name-connection Give a connection a logical name
ping
Send echo messages
reload
Halt and reload system
resume
Make the named connection be current
send <line>|* Send message to a terminal line or lines
setup
Initialize system configuration
show <cmd>
Information commands, enter "show ?" for list
systat
Show terminal lines and users
telnet <host> Connect to host using telnet protocol
terminal
Change terminal’s parameters, enter "terminal ?"
test
Run hardware tests, enter "test ?"
trace <address> Trace route to <address>
undebug
Disable debugging functions, enter "undebug ?" for list
where
Show open connections
which-route
Displays CLNS route table lookup.
write
Write configuration memory, enter "write ?" for list
<cr>
To resume connection
To return to the user-level prompt, enter disable at the EXEC prompt.
The EXEC command CONFIGURE begins the configuration mode, where you
enter the commands to configure your router for its particular routing or bridging
function. The following section describes the use of this command.

Entering Configuration Mode
Use the privileged EXEC command CONFIGURE to begin configuration of the
router.
Begin by entering the privileged level of the EXEC. This is done by entering the
ENABLE command at the EXEC prompt:
Router> enable

2–8 First-Time Startup and Basic Configuration

First-Time Startup and Basic Configuration
Entering Configuration Mode
The EXEC then prompts you for a privileged-level password:
Password:
Enter the password. For security purposes, the password will not be displayed.
(Also note that the password is case-sensitive.) When you enter the correct
password, the system displays the privileged-mode system prompt:
Router#
To begin configuration mode, enter the CONFIGURE command at the privilegedmode prompt:
Router# configure
When you enter this command, the EXEC prompts you for the source of the
configuration subcommands.
Configuring from terminal, memory, or network [terminal]?
The default is to enter the commands from the terminal console. Pressing the
Return key begins this configuration method. Each configuration technique
(terminal, memory, and network) is described in more detail later in this chapter.
The EXEC provides you with a simple editor for entering the configuration
commands, and explains the editing functions:
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
Table 2–1 lists the edit key functions and their meanings.
Table 2–1 Configuration Edit Keys
Key

Meaning

Delete or Backspace

Erases one character.

Ctrl/W

Erases a word.

Ctrl/U

Erases a line.

Ctrl/R

Redisplays a line.

Return

Executes single-line commands.

Ctrl/Z

Ends configuration mode and returns to the
EXEC.

Entering the Configuration Commands
The configuration subcommands are categorized by these functions:
•

Global configuration commands—Define system-wide parameters.

•

Interface subcommands—Define the characteristics of an interface (a serial
or Ethernet interface, for example) and must be preceded by an INTERFACE
command.

First-Time Startup and Basic Configuration 2–9

First-Time Startup and Basic Configuration
Entering Configuration Mode
•

Line subcommands—Define the characteristics of a serial terminal line and
must be preceded by a LINE command.

•

Router subcommands—Configure an IP routing protocol and must be preceded
by a ROUTER command.

The command descriptions include the command types and give examples of their
use.
As with EXEC commands, you can enter configuration subcommands in uppercase
letters, lowercase letters, or both. You can also shorten all commands and other
keywords to unique abbreviations. You can add comments by preceding the line
with an exclamation point (!). Comments do not affect command processing.
The router does not display confirmation messages as it executes the commands.
If the router encounters a problem, it displays an error message on the console
terminal.
In most cases, you can negate a configuration subcommand or restore a default
by entering no before the subcommand keyword. You usually can omit the
arguments of the subcommand when you negate it with no. The command
descriptions note any exceptions to these rules.

Examples of Configuration Files
The following examples of configuration files illustrate how to enter the
configuration commands.
The EXEC accepts commands in uppercase and lowercase letters. Exclamation
points are not parsed and serve as comment lines and delimiters between
configuration commands.
Global Configuration Commands
Use global configuration commands to enable functions that affect the entire
system rather than a particular line or interface, and can appear any place within
the configuration file. An example of this is the global configuration command to
define the host name, or the name of the router:
hostname router-1
Commands to enable a particular routing or bridging function are also global
configuration commands. The following example illustrates how to enable the
Xerox Network System (XNS) routing protocol:
xns routing 0123.4567.abcd
Once enabled, interface characteristics for XNS routing are specified using the
INTERFACE command and XNS-specific interface subcommands. Command
descriptions in the sections describing configuration will define the command
type.
Interface Subcommands
Interface subcommands modify the operation of an interface such as an Ethernet
or serial port. Interface subcommands always follow an INTERFACE command,
which defines the interface type.

2–10 First-Time Startup and Basic Configuration

First-Time Startup and Basic Configuration
Entering Configuration Mode
The following example illustrates how to enable XNS network 1 on interface
Ethernet 0:
interface ethernet 0
xns network 1
If you forget to enter the INTERFACE command, the system displays the message
"must specify a network interface."
Line Subcommands
Line subcommands modify the operation of a serial terminal line. Line
subcommands always follow a LINE command, which defines the line number. If
you forget to enter the LINE command, the system displays the message "must
specify a line or range of lines."
The following example illustrates how to set the password on line 5:
line 5
password secretword
Router Subcommands
Router subcommands are used to configure IP routing protocol characteristics and
always follow a ROUTER command. The following example illustrates how to set
the maximum hop metric for the Cisco IGRP routing protocol:
router igrp
metric maximum-hops 150
If you forget to enter the ROUTER command, the system displays the message
"must specify a routing protocol."
Remember to enter Ctrl/Z to end your configuration sessions and to use the
DISABLE command to leave the privileged mode.

Creating the Configuration File
If you used the SETUP facility’s interactive dialog prompts to start your
configuration file, it was saved in nonvolatile memory when you finished the
prompts. If you chose not to create your configuration file this way, there are
several options you now can choose from to create the configuration file.
The router holds configuration information in two places—in running memory
and in nonvolatile memory. Configuration information in running memory is
temporary and will not be stored if power is shut off. Configuration information
in nonvolatile memory is always available.
Use the EXEC command WRITE MEMORY to copy current (running)
configuration information to nonvolatile memory. This command stores all
nondefault configuration information as configuration commands in text format.
The command also records a checksum for the information to protect against data
corruption.
The EXEC command SHOW CONFIGURATION displays information stored in
nonvolatile memory. You can use this command and the WRITE TERMINAL
command to find differences between the current configuration (that in running
memory) and that stored in nonvolatile memory. Use the EXEC command WRITE
ERASE to clear the contents of nonvolatile memory.

First-Time Startup and Basic Configuration 2–11

First-Time Startup and Basic Configuration
Entering Configuration Mode
WRITE commands create their output by examining the state of the system
currently running. The output produced by the WRITE commands is generated
by the software, and will not necessarily match the text the user entered to create
the current configuration.
The router also allows you to store the configuration file on a network host. (This
allows you to use an editor on the host to edit and create the configuration file.)
Use the EXEC command WRITE NETWORK to copy the current configuration
information to a server host on the network. Use of this command is described
later in this section.
Configuring from the Console
To issue configuration commands from the console terminal, enter the EXEC
command CONFIGURE at the privileged-level EXEC prompt and enter
configuration mode.
The router responds with this prompt asking you to specify the terminal, a file, or
nonvolatile memory as the source of configuration commands:
Configuring from terminal, memory, or network [terminal]?
To begin configuration, enter terminal at the prompt or press Return (since
terminal is the default) to start command collection. (See the section Entering
Configuration Mode in this chapter for more information.)
During command collection, the router accepts one configuration command per
line. You can enter as many configuration subcommands as you want.
Press Ctrl/Z when you finish entering configuration commands. This returns you
to the EXEC, where you can test your configuration or write the configuration
commands to memory.
At periodic intervals, you will want to write the configuration information into
nonvolatile memory or to a configuration file stored on a remote host. This will
make checking, adding information to, and booting the configuration file an easier
task. The procedures for writing information to nonvolatile memory are described
next.
Writing the Configuration File to Nonvolatile Memory
After you enter the desired configuration information at the console terminal,
use the privileged EXEC command WRITE MEMORY to make a copy of the
configuration information in the nonvolatile memory. Nonvolatile memory stores
the current configuration information in text format as configuration commands,
recording only nondefault settings. The memory is checksummed to guard against
corrupted data.
As part of its startup sequence, the router startup software always checks
for configuration information in the nonvolatile memory. If the nonvolatile
memory holds valid configuration commands, the router executes the commands
automatically at startup. If the router detects a problem with the nonvolatile
memory or the configuration information it contains, the router may enter the
setup mode, prompting for configuration information. Problems can include a
bad checksum for the information in the nonvolatile memory and the absence of
critical information.
To display the configuration information stored in the nonvolatile memory, enter
the SHOW CONFIGURATION EXEC command at the privileged-mode EXEC
prompt.

2–12 First-Time Startup and Basic Configuration

First-Time Startup and Basic Configuration
Entering Configuration Mode
To clear the contents of the nonvolatile memory, enter the WRITE ERASE EXEC
command at the privileged level EXEC prompt.
To reexecute the configuration commands stored in nonvolatile memory, enter
memory at the configure mode prompt:
Configuring from terminal, memory, or network [terminal]? memory
Writing the Configuration File to a Remote Host
To store configuration information on a remote host, enter the privileged EXEC
command WRITE NETWORK. This command sends a copy of the current
configuration information to a remote host. The command will prompt you for the
destination host’s address and a file name, as the following example illustrates.

Example
Tokyo# write network
Remote host [131.108.2.155]?
Name of configuration file to write [tokyo-confg]?
Write file tokyo-confg on host 131.108.2.155? [confirm] y
Writing tokyo-confg...
[OK]
To retrieve and/or add to the configuration information stored on a host file on a
device on your network, enter network at the configure mode prompt (see the
section Entering Configuration Mode for more information):
Configuring from terminal, memory, or network [terminal]? network
The system will ask you to select a host or network configuration file, for the
address of the host, and for a file name. The following example illustrates this
process.

Example
Host or network configuration file [host]?
IP address of remote host [255.255.255.255]? 131.108.2.155
Name of configuration file [tokyo-confg]?
Configure using tokyo-confg from 131.108.2.155? [confirm] y
Booting tokyo-confg from 131.108.2.155: !! [OK - 874/16000 bytes]

Setting Up Auto Load of the Configuration File
The router may be configured to automatically load additional configuration
information from a network host. You may want to keep an up-to-date version of
configuration information on another host, where you can change it as necessary,
and use the nonvolatile memory as a bootstrap or backup mechanism. You
can instruct the router to load configuration information over the network by
entering the SERVICE CONFIG subcommand and then writing the information
to nonvolatile memory using the WRITE MEMORY command. Loading
configuration information over the network is the default if nonvolatile memory is
not installed. (The SERVICE CONFIGURATION subcommand is described in the
section Tailoring Use of Network Services in Chapter 4.)

First-Time Startup and Basic Configuration 2–13

First-Time Startup and Basic Configuration
Entering Configuration Mode
After loading configuration information from the nonvolatile memory, the router
will attempt to load two configuration files from remote hosts. The first is the
network configuration file, which contains commands that apply to all routers and
terminal servers on a network. The second is the host configuration file, which
contains commands that apply to one router in particular.

Using TFTP to Load Configuration Files or System Images
The router uses the Trivial File Transfer Protocol (TFTP) to load and save
configuration files.

Note
TFTP is defined in RFC 783. The details of setting up a TFTP server
process and installing system images or configuration files on the server
host vary from one operating system to another. See the documentation
for your host computer if you need more information about TFTP support.

Loading Configuration Files
The default name of the network configuration file is network-confg. The default
name for the host configuration file is taken from the host name. The host name
can be specified by the HOSTNAME configuration subcommand or can be derived
from the Domain Name System (DNS); see the section Setting the Host Name
in Chapter 4 for more information. To form the host configuration file name,
the network server converts the host name to lowercase, stripped of any DNS
information, and appends "-confg." If no host name information is available,
the default host configuration file name is router-confg. Other names for these
configuration files can be set using the BOOT command, which is described in the
section Setting Configuration File Specifications in Chapter 4.
service config
no service config

To enable the loading of network configuration files at router reboot time, use
the SERVICE CONFIG command. The NO version of this command (the default)
disables the loading of these files.
If the router fails to load a configuration file during startup, it tries again every
ten minutes (default setting) until a host provides the requested files. With each
failed attempt, the router displays a message on the console terminal.
If the router is unable to load the file named network-confg, it displays the
following message:
Booting network-confg... [timed out]

2–14 First-Time Startup and Basic Configuration

First-Time Startup and Basic Configuration
Entering Configuration Mode
Note
Be aware that the system treats network and host configuration files
differently when loading new parameters. When a host configuration
file is loaded, all terminal line parameters are cleared before setting any
new parameters. When a network configuration file is loaded, no old
parameters are cleared. This means that terminal line parameters set by
the network configuration file, which are generally loaded first, will be
reset by the host configuration file, which is generally loaded second.

Using Flash Memory for Storing and Booting System Software
System software images can be written to flash memory for booting. Refer to
the section Storing and Booting System Software Using the Flash Memory in
Chapter 4 for a description of the flash commands.

Reloading the System
Use the following EXEC command to halt and restart the DECbrouter 90:
reload
If the system is set to restart on error, it reboots itself.

First-Time Startup and Basic Configuration 2–15

3
Using Terminals
This chapter describes use of physical and virtual terminals on the DECbrouter
90 product. The tasks covered include:
•

Making Telnet server connections from a console attached to the router/bridge

•

Making local changes to the terminal parameters

•

Using the Digital MOP terminal server

This chapter concludes with an alphabetical summary of the commands it
describes.

Making and Managing Terminal Connections
A TCP/IP Telnet connection is the basic way to communicate from a terminal to a
host on a network. The DECbrouter 90 provides Telnet communication as defined
in RFC 854 and the MIL STD 1782 specification.

Making Telnet Connections
To start a Telnet connection, enter a host name or a dotted-decimal Internet
address at the EXEC prompt. You may precede the host name or Internet
address with the command CONNECT or TELNET. This can be helpful if the
host name you want to use conflicts with a router command name.
The router automatically numbers connections for you. Several commands use
these numbers to identify connections, and you can display them using the
WHERE command described later in this chapter.
If you use a host name, the router must first find the corresponding Internet
address. To find this address, the router searches its host-name-to-address cache.
If the name is not in the cache, the router uses a dynamic name lookup method.
This method enables the router to query a set of server hosts for the address.
As an option, you can specify a decimal TCP port number after the host name or
Internet address when starting a Telnet connection. Normally, the router uses
the default Telnet server port, port number 23 (decimal).
After the router determines the Internet address, or if you specify the address
directly, the router attempts to connect with the Telnet server port at that
address. If the connection attempt fails, the router displays a message to that
effect and returns to the EXEC interpreter.
If the connection attempt succeeds, you can communicate with the server host
as a terminal of that host. When you log off the host, the router returns to the
EXEC interpreter.

Using Terminals 3–1

Using Terminals
Making and Managing Terminal Connections
Example
To connect to a host named router-1, enter that name at the prompt, as seen in
this example.
Router> router-1
This example illustrates how to connect to a router with IP address 103.81.25.2:
Router> connect 103.81.25.2

Establishing Multiple Connections
The router provides an escape sequence with which you can leave a Telnet
connection without terminating it and return to the EXEC interpreter. This
allows you to have any number of concurrent Telnet connections open and to
switch back and forth between them. Follow these steps to switch between
connections:
1. Enter the escape sequence, which is usually the default key sequence Ctrl/^
X. This sequence is entered by pressing the Ctrl and ^ keys simultaneously,
letting go, then pressing the X key.
2. At the system command prompt, enter the command to open another
connection.
To make a new connection, use the procedure described in the previous section
Making Telnet Connections. To return to an existing connection, enter the
RESUME command. Enter the WHERE command to show your open connections.
You can change the first part of the escape sequence with the ESCAPECHARACTER command; see the section Setting the Escape Character in
Chapter 4.

Listing Connections
Use the following command to get a listing of connections:
where
This command displays information about open connections associated with the
current terminal line, as seen in the example that follows.
Router> where
Conn Host
1 DREGGS
2 EMBER
* 3 CLASH

Address
130.106.19.50
130.106.20.33
130.106.21.24

Byte Idle Conn Name
0
0 DREGGS
0
0 EMBER
0
0 CLASH

The information includes the connection number, host name, address, number of
characters waiting to be sent to the terminal, idle time, and connection name. An
asterisk (*) indicates the current connection.

3–2 Using Terminals

Using Terminals
Making and Managing Terminal Connections
Resuming a Previous Connection
Use the EXEC RESUME command to resume a connection. This command has
the following syntax:
resume [connection]
This command provides three ways to resume a previous connection:
•

By entering the RESUME command with a connection number

•

By entering only the connection number

•

By pressing the Return key to return to the most recent connection.

The WHERE command provides the connection number.
The following examples demonstrate use of the RESUME command.

Examples
This command resumes connection 2:
Router> resume 2
You also can omit the command name and simply type the connection number to
resume that connection. This example resumes connection 3:
Router> 3
To resume the most recent connection, press the Return key.

Naming a Connection
To name a connection, use the following command:
name-connection
This command assigns a logical name to a connection. The EXEC prompts for
the connection number and name to assign when you enter this command. The
WHERE command displays a list of the assigned logical connection names.

Exiting a Session
To exit a session, use one of the following commands:
exit
quit
The EXIT and QUIT commands terminate the incoming connection and all
outgoing connections from the router. Enter one of these commands when you are
finished with all sessions.

Using Terminals 3–3

Using Terminals
Making and Managing Terminal Connections
Disconnecting
To disconnect from a specified connection, use the following command:
disconnect [connection]
The optional argument connection is a connection name or number; the default is
the current connection.
Do not use the DISCONNECT command to end a session. Instead, log off the
host, thus allowing the host to initiate the disconnect. If you cannot log off the
host, use the DISCONNECT command.

Resetting a Line
To reset a terminal line, use the following privileged EXEC command:
clear line line-number
This command aborts any connections, terminates the associated processes, and
resets the data structures associated with a terminal line.
The argument line-number specifies the terminal line number.

Executing Special Telnet Commands
The Telnet software supports special Telnet commands in the form of Telnet
sequences that map generic terminal control functions to operating systemspecific functions.
To issue a special Telnet command, type the escape sequence (usually Ctrl/^)
and then a command character. You can type the command character either as
you hold down Ctrl or with Ctrl released, and you can type either uppercase or
lowercase letters.
Table 3–1 lists the special Telnet commands.
Table 3–1 Special Commands in the Digital Systems Telnet Implementation
Command Name

Command Characters

Break

Ctrl/^, B

Interrupt Process (IP)

Ctrl/^, C

Erase Character (EC)

Ctrl/^, H

Abort Output (AO)

Ctrl/^, O

Are You There? (AYT)

Ctrl/^, T

Erase Line (EL)

Ctrl/^, U

At any time during an active Telnet session, you can list the Telnet commands by
typing this command at the system prompt:
Ctrl/^ ?
This is done by entering the escape sequence followed by a question mark. This
command displays an online table of the special Telnet commands, for quick
reference.

3–4 Using Terminals

Using Terminals
Making and Managing Terminal Connections
A sample of this table follows (the Ctrl key is represented by the first ^
character).
[Special telnet escape help]
^^B sends telnet BREAK
^^C sends telnet IP
^^H sends telnet EC
^^O sends telnet AO
^^T sends telnet AYT
^^U sends telnet EL

Incoming Telnet Connections
In addition to the console terminal, each router supports up to five incoming
Telnet connections. Each of these connections can start an EXEC interpreter
process on the router.
The user of an incoming Telnet connection can gain access to the privileged
EXEC commands through the ENABLE command, which requires a password.
With access to the complete EXEC command set, the incoming connection acts
as a remote console. A remote console connection provides a convenient way to
monitor and adjust router operation.
You can control access to the router with access lists; see the DECbrouter 90T
Products, Configuration and Reference, Volume 2, Chapter 5, "Routing IP" for
more information.
The router supports the following Telnet options:
•

Echo

•

Binary Transmission

•

Suppress Go Ahead

•

Terminal Type

•

Send Location

LAT EXEC Commands
The commonly used Digital commands that follow are supported on the
DECbrouter 90. Use this HELP command to obtain information about LAT
EXEC commands:
h
Use this LOGOUT command to exit LAT EXEC mode and free the line:
lo

Displaying TCP Connections
To show the status of a TCP connection, enter this EXEC command:

show tcp [line-number]

Using Terminals 3–5

Using Terminals
Making and Managing Terminal Connections
The SHOW TCP command displays the status of all TCP connections. Specify
the optional argument line-number in octal to display the status of the TCP
connections for a particular line. The following example shows the command
output:
con0 (console terminal), connection 1 to host MATHOM
Connection state is ESTAB, I/O status: 1, unread input bytes: 1
Local host: 192.31.7.18, 33537 Foreign host: 192.31.7.17, 23
Enqueued packets for retransmit: 0, input: 0, saved: 0
Event Timers (current time is 2043535532):
Timer:
Retrans TimeWait
AckHold
SendWnd KeepAlive
Starts:
69
0
69
0
0
Wakeups:
5
0
1
0
0
Next:
2043536089
0
0
0
0
iss: 2043207208 snduna: 2043211083 sndnxt: 2043211483
sndwnd: 1344
irs: 3447586816 rcvnxt: 3447586900 rcvwnd:
2144 delrcvwnd: 83
RTTO: 565 ms, RTV: 233 ms, KRTT: 0 ms, minRTT: 68 ms, maxRTT: 1900 ms
ACK hold: 282 ms
Datagrams (max data segment is 536 bytes):
Rcvd: 106 (out of order: 0), with data: 71, total data bytes: 83
Sent: 96 (retransmit: 5), with data: 92, total data bytes: 4678

Displaying Active Sessions
To show the current active sessions, use the following command:
show sessions
The SHOW SESSIONS command provides information about open Telnet
connections. This command can be run at the user-level prompt.

Displaying Information About Active Lines
The SHOW USERS and SYSTAT EXEC commands display information about
the active lines of the router, including the line number, connection names, and
terminal location.
show users [all]
systat [all]

Specify the optional keyword all to display information for both active and
inactive lines. These commands enable monitoring of virtual terminal use. You
can issue these commands at the user-level prompt. They are synonymous.

Changing Terminal Parameters
The following sections describe how to change the terminal parameters using the
TERMINAL commands. The new settings temporarily override those made with
the line configuration subcommands described in Chapter 4.
To obtain information about the terminal configuration parameter settings
for the current terminal line, use the SHOW TERMINAL command. To display
information about the active ports of the server, use the SHOW USERS command.
The information displayed includes the line number, connection name, idle time,
and terminal location.

3–6 Using Terminals

Using Terminals
Changing Terminal Parameters
Some TERMINAL commands use the decimal representation of an ASCII
character as an argument. See the DECbrouter 90 Configuration and Reference,
Volume 3, Appendix E, "ASCII Character Set," for ASCII-to-decimal conversion
information.
To display a list of commands that you can enter to change the hardware and
software parameters of the current terminal line, use the command:
terminal ?
Each command has a no variation that undoes the local setting.

Changing the Terminal Screen Width
To set or unset the number of characters (columns) on a single line of the current
terminal screen, use the terminal width command:
terminal width columns
terminal no width
The login protocol uses the argument columns to set up terminal parameters on a
remote host.

Example
This example sets the terminal width to 132 columns.
Router> terminal width 132

Changing the Terminal Screen Length
To set or unset the number of lines on the screen of the current terminal, use the
TERMINAL LENGTH command:
terminal length screen-length
terminal no length
The argument screen-length is the desired number of lines.
The server uses this value to determine when to pause during multiple-screen
output. The default length is 24 lines. A value of zero disables pausing between
screens of output. The screen length specified can be learned by hosts.

Changing the Terminal Escape Character
To set or remove the escape character for the current terminal line, use the
TERMINAL ESCAPE-CHARACTER command:
terminal escape-character decimal-number
terminal no escape-character
The argument decimal-number is the ASCII decimal representation of the desired
escape character or an escape sequence (Ctrl/P, for example). Typing the escape
character followed by the X key returns you to the EXEC when you are connected
to another computer. The default escape character is Ctrl/^ X. (See DECbrouter

Using Terminals 3–7

Using Terminals
Changing Terminal Parameters
90 Configuration and Reference, Volume 3, Appendix E, "ASCII Character Set,"
for a list of ASCII characters.)
The operating software interprets the Break key on the console as an attempt to
halt the system.
Note
Depending upon the configuration register setting, console breaks either
will be ignored or will cause the server to shut down. The Break key
cannot be used as the escape character on the router.

Example
This example sets Ctrl/P as the escape character:
Router> terminal escape-character 17

Displaying the Debug Messages on the Console and Terminals
To display the debug message on the console and terminals, use the TERMINAL
MONITOR command:
terminal monitor
terminal no monitor
The TERMINAL MONITOR command copies DEBUG command output and
system error messages to the current terminal as well as to the console terminal.
To use this command, you must first enter the ENABLE command and then the
password to access the privileged command mode.

Establishing Input Notification
To establish input notification, use the TERMINAL NOTIFY command:
terminal notify
terminal no notify
When you have multiple concurrent connections, you may want to know when
output is pending on a connection other than the current connection. For
example, you may want to know when another connection receives mail or a
message. The TERMINAL NOTIFY command causes the router to notify you of
pending output. The TERMINAL NO NOTIFY command ends such notifications.

Changing the Character Padding
To set the character padding on the current terminal line, use the TERMINAL
PADDING commands:
terminal padding decimal-number count
terminal no padding decimal-number
The argument decimal-number is the ASCII decimal representation of the
character. The argument count is the number of NULL bytes sent after that
character. (The DECbrouter 90 Configuration and Reference, Volume 3, Appendix
E, "ASCII Character Set," provides a list of the ASCII characters.)
3–8 Using Terminals

Using Terminals
Changing Terminal Parameters
The TERMINAL NO PADDING command ends this padding.

Example
This example pads RETURNS (ASCII character 25) with 20 NULL bytes:
Router> terminal padding 25 20

Displaying Terminal Parameter Settings
To display the configuration parameter settings for the current terminal, use this
EXEC command:
show terminal
This command can be issued at the user-level prompt.

Setting Widths for International Character Sets at the User Level
The number of significant bits for characters passed in EXEC and configuration
modes, and for special characters, can be set. Changing these widths allows the
use of international character sets.
These settings can be configured globally, by interface, and locally at the user
level. See Chapter 4 for global and interface configuration information.
Use the following command to change the ASCII character widths for characters
entered at the EXEC and during configuration mode:
terminal exec-character-bits {8 | 7}
This EXEC command overrides the default-value EXEC-CHARACTER-BITS
global configuration command. Configuring the EXEC character width to 8 bits
allows you to add special graphical and international characters in banners and
prompts. When the user exits the system, the character width is reset to the
default value established by the global configuration command. See Chapter 4 for
more information.
Note
Setting the EXEC character width to eight bits can cause failures. If a
user on a terminal that is sending parity enters the command HELP,
an "unrecognized command" message appears because the system is
reading all eight bits, although the eighth bit is not needed for the HELP
command.

Example
This example temporarily configures a router to use a full 8-bit user interface
for system banners and prompts. This allows the use of additional graphical and
international characters.
gw> terminal exec-character-bits 8

Using Terminals 3–9

Using Terminals
Changing Terminal Parameters
Use the following command to temporarily change the ASCII character widths to accept special
characters typed in during data connection:
terminal special-character-bits {8 | 7}
The TERMINAL SPECIAL-CHARACTER-BITS command temporarily allows
the server to support international character sets. It overrides the default-value
special-character-bits global configuration command and is used to compare
character sets typed by the user with the special character available during a
data connection. Special characters include software flow control and escape
characters. Configuring the width to 8 allows you to use twice as many special
characters as with the 7-bit setting. When the user exits the system, the
command is reset to the default value established by the global configuration
command. See Chapter 4 for more information.

Example
This example temporarily configures full 8-bit comparisons of flow control and
interrupt characters to allow more special characters to be accepted. When you
exit the system, character width will be reset to the width established by the
global configuration command.
gw> terminal special-character-bits 8

Using the Digital MOP Server
All Digital internetworking products implement Digital maintenance operation
protocol (MOP) for Ethernet interfaces. The MOP server supports the request ID
message, periodic system ID messages, and the remote console carrier functions.
The MOP server periodically multicasts a system ID message, which is used
by the DECbrouter 90 Ethernet configurator to determine what stations are
present in an Ethernet network. The configurator is controlled by the network
control program (NCP) command DEFINE MODULE CONFIGURATOR. For
more information on this command, consult DECnet–VAX documentation.
The MOP server supports the Digital remote console function. In this capacity, a
system manager on a DECnet system that does not include TCP/IP can create a
virtual terminal connection to a DECbrouter 90. The NCP commands CONNECT
NODE and CONNECT VIA are used to connect to the remote console. Due to the
nature of the MOP server, only a single inbound connection per Ethernet interface
is supported. The MOP server does not contain the mechanisms necessary to
support more than one connection at a time.
MOP is not a routable protocol. To bridge the MOP console carrier and system
ID functions, enable bridging for protocol type 6002. The periodic system ID
messages are sent to the multicast address AB00.0002.0000.
The EXEC command DEBUG MOP reports events occurring within the MOP
server, including reception of request ID messages, transmission of system ID
messages, and reservation and release of the remote console.

3–10 Using Terminals

Using Terminals
EXEC Terminal Command Summary

EXEC Terminal Command Summary
This section alphabetically lists the EXEC commands described in this chapter.
clear line line-number
Aborts connections and processes and resets the line. Argument line-number
specifies the line.
{connect | telnet} [connection]
Either of the commands connects to a remote host using the Telnet protocol.
The optional argument connection specifies a host name or an IP address.
Ctrl/^ ?
Lists the special Telnet commands in the form of Telnet sequences that map
generic terminal control functions to operating system-specific functions.
Enter this command at the system prompt.
disconnect [connection]
Closes the specified connection. The optional argument connection is a
connection name or number; the default is the current connection.
exit
quit
Either of these commands terminates the EXEC command processor and
closes any active Telnet sessions.
name-connection
Assigns a logical name to a connection. The EXEC prompts for the connection
number and name to assign when you enter this command.
resume [connection]
Resumes a connection. The optional argument connection is a connection
name or number.
show sessions
Provides information about open Telnet connections.

Using Terminals 3–11

Using Terminals
EXEC Terminal Command Summary
show tcp[line-number]
Displays the status of all TCP connections. Specify the optional argument
line-number in octal to display the status of the TCP connections for a
particular line.
show terminal
Displays information about the terminal configuration parameter settings for
the current terminal line and the active ports of the server. The optional all
keyword requests information for both active and inactive ports.
show users [all]
systat [all]
Displays information about active lines. The optional all keyword provides
information about inactive as well as active ports.
terminal ?
Lists commands you can enter to change hardware and software parameters
of the current line.
terminal [no] escape-character decimal-number
Sets the escape character for the current terminal line. The argument
decimal-number is either the ASCII decimal representation of the desired
escape character or an escape sequence. The default escape character is
Ctrl/^ X. The no version of the command removes the specified escape
character for the current terminal line.
terminal exec-character-bits {8 | 7}
Changes the ASCII character widths for characters entered at the EXEC and
during configuration mode.
terminal [no] length screen-length
Sets the length of the terminal to screen-length lines. The default length is
24 lines. The no version of the command unsets the number of lines.

3–12 Using Terminals

Using Terminals
EXEC Terminal Command Summary

terminal [no] monitor
Displays the debug message on the console and terminals. It copies DEBUG
command output and system error messages to the current terminal as well
as to the console terminal. To use this command, you must first enter the
ENABLE command and then the password to access the privileged command
mode. The no version of the command discontinues the display of the debug
message.
terminal [no] notify
Enables notification to a terminal when output to it is generated on any of its
active sessions. The no version of this command disables notification.
terminal [no] padding decimal-number count
Sets the character padding on the current terminal line. The argument
decimal-number is the ASCII decimal representation of the character. The
argument count is the number of NULL bytes sent after that character. (The
DECbrouter 90 Configuration and Reference, Volume 3, Appendix E, "ASCII
Character Set," provides a list of the ASCII characters.) The TERMINAL NO
PADDING command ends this padding.
terminal special-character-bits {8 | 7}
Temporarily changes the ASCII character widths to accept special characters
typed in during data connection.
terminal [no] width columns
Sets the number of characters (columns) on a single line of the current
terminal screen. The login protocol uses the argument columns to set up
terminal parameters on a remote host. The no version of the command
unsets the number of characters (columns) on the single line of the current
terminal screen.
where
Displays information about open connections associated with the current
terminal line and provides the connection number.

Using Terminals 3–13

4
Configuring the System
This chapter describes how to configure the system. System configuration tasks
include:
•

Setting global system characteristics such as the host name and console
banner message

•

Defining the size of the system buffers

•

Changing the system boot file specifications

•

Storing and booting system software images with flash memory

•

Establishing system and line passwords and system security

•

Defining network services such as the IP Finger protocol

•

Enabling and directing the logging of system debugging messages

•

Configuring the console and virtual terminal lines

The chapter concludes with alphabetical summaries of the commands it describes.

Configuring the Global System Parameters
The following sections contain procedures and command descriptions for
configuring the global system characteristics: host name and passwords and
configuring system security and system management functions. The global
configuration commands described in the following sections are entered in
configuration mode. See the section Entering Configuration Mode in Chapter 2
for the procedures used to enter into this mode.

Setting the Host Name
Enter the HOSTNAME global configuration command to specify the host name
for the router. The hostname is used in prompts and default configuration file
names.
hostname name
The argument name is the new host name for the router and is case-sensitive.
The default host name is Router.

Example
This command changes the host name to sandbox.
hostname sandbox

Configuring the System 4–1

Configuring the System
Configuring the Global System Parameters
Displaying Banner Messages
A banner is the message that the EXEC command interpreter displays whenever
a user starts any EXEC process or activates a line. The general form of the
BANNER global command follows.
banner {motd | exec | incoming} c text c
no banner {motd | exec | incoming} c text c

The motd, exec, and incoming keywords control when the banner message is
displayed. The use of these keywords is described in the following sections.
The argument c specifies a delimiting character of your choice. The argument
text specifies the message to be shown on the screen whenever an interface line is
activated.
The default keyword is motd (message of the day) if none is specified.
The no version of these commands removes the specified banner, and the NO
BANNER command removes the motd.
Follow banner with one or more blank spaces, then type the delimiting character,
followed by one or more lines of text. Terminate the message by typing the
delimiting character a second time. There is no limit to the number of characters
that can be used for the banner, with the exception of buffer limits and what is
appropriate for a banner.

Example
The following example uses the pound sign character as a delimiting character:
banner motd #
Building power will be off from 7:00 AM until 9:00 AM this coming Tuesday.
#
Note
You cannot use the delimiting character in the banner message.

Displaying a Message-of-the-Day Banner
To specify a general-purpose message-of-the-day banner, use the BANNER MOTD
global configuration command.
banner motd c text c
This command displays a message-of-the-day banner whenever any type of
connection is established; for example, when a line is activated, or when an
incoming Telnet connection is created. Use this banner for messages that affect
all users of the router (for example, for system reboots).

4–2 Configuring the System

Configuring the System
Configuring the Global System Parameters
Note
The command BANNER is equivalent to the command BANNER MOTD
except that with banner, the banner is displayed on incoming connections
only.

Displaying a Banner with an EXEC Process
To display a message when an EXEC process is created, use the BANNER EXEC
global configuration command.
banner exec c text c
This command specifies a message to be displayed when an EXEC process is
created (for example, when a TTY line is activated, or an incoming connection
is established to a VTY). This banner is designed for messages that affect only
interactive terminal users of the router.
Displaying an Incoming Message Banner
To display an incoming message to a particular terminal line, use the BANNER
INCOMING global configuration command.
banner incoming c text c
This command specifies a message to be displayed on incoming connections
to particular terminal lines (for example, lines used for "milking machine"
applications).
Note
Messages are never displayed on incoming stream-type connections,
because they might interfere with printer daemons.
The EXEC banner can be suppressed on certain lines by using the NO EXECBANNER line subcommand (described in the section Suppressing Banner
Messages later in this chapter). Lines so configured will not display the EXEC or
MOTD banners when an EXEC is created.
Order of Banner Displays
Banners and messages are displayed in the following order:
1. Any banner motd message
2. Any banner incoming message. At this point, the user logs in, if required.
3. Any banner exec message

Example
This example illustrates how to display a message-of-the-day banner and
a message that will be displayed when an EXEC process is created. Use
the BANNER global configuration commands and NO EXEC-BANNER line
subcommand to accomplish these settings.

Configuring the System 4–3

Configuring the System
Configuring the Global System Parameters
! Both messages are inappropriate for the VTYs.
line vty 0 4
no exec-banner
!
banner exec /
This is training group server.
Unauthorized access prohibited.
/
!
banner motd /
The server will go down at 6pm for a software upgrade
/

Setting Default Widths for International Character Sets
Digital software allows you to set default widths for characters such as banners
and prompts, and for special characters such as flow control, hold, escape, and
disconnect characters. Modifying the character width for EXEC and special
characters allows you to include international characters in banners, prompts,
and special characters.
Use these global configuration commands to specify the number of significant
characters for EXEC and special characters.
default-value exec-character-bits {8 | 7}
default-value special-character-bits {8 | 7}
The DEFAULT-VALUE EXEC-CHARACTER-BITS command configures the
character widths of EXEC and configuration command characters. The
default value is 7 bits, which results in the use of a 7-bit ASCII character
set. Configuring the EXEC character width to 8 bits allows you to add special
graphical and international characters in banners and prompts.
Note
Setting the EXEC character width to 8 bits can cause failures. If a user
on a terminal that is sending parity enters the command HELP, an
"unrecognized command" message appears because the system is reading
all 8 bits, although the eighth bit is not needed for the HELP command.
The DEFAULT-VALUE SPECIAL-CHARACTER-BITS command configures the
number of characters used in special characters such as software flow control,
hold, escape, and disconnect characters. The default special-character width is 7.
Configuring the width to 8 allows you to use twice as many special characters as
with the 7-bit setting.
See the section Setting Widths for International Character Sets for the Interface
later in this chapter for configuration examples and line character-width
commands. See Chapter 3 for EXEC-level character width commands.

4–4 Configuring the System

Configuring the System
Configuring the Global System Parameters
Setting the System Buffers
In normal system operation, there are several pools of different-sized buffers.
These pools grow and shrink based upon demand. Some buffers are temporary
and are created and destroyed as warranted. Other buffers are permanently
allocated and cannot be destroyed. The BUFFERS command allows a network
administrator to adjust initial buffer pool settings, as well as the limits at which
temporary buffers are created and destroyed.
Note
Normally it is not necessary to adjust these parameters; do so only after
consulting with Digital staff. Improper settings could adversely impact
router performance.
The full syntax of the BUFFERS command follows.
buffers {small | middle | big | large | huge} {permanent | max-free |
min-free | initial} number
no buffers {small | middle | big | large | huge} {permanent | max-free |
min-free | initial} number
First choose the keyword that describes the size of buffers in the pool—small, big,
huge, and so on. The default number of the buffers in a pool is determined by the
hardware configuration and can be displayed with the EXEC SHOW BUFFERS
command.
The next keyword specifies the buffer management parameter to be changed and
can be one of the following:
•

permanent—The number of permanent buffers that the system tries to
allocate. Permanent buffers normally are not deallocated by the system.

•

max-free—The maximum number of free or unallocated buffers in a buffer
pool.

•

min-free—The minimum number of free or unallocated buffers in a buffer
pool.

•

initial—The number of additional temporary buffers that should be allocated
when the system is reloaded. This keyword can be used to ensure that the
router has the necessary buffers immediately after reloading in a high traffic
environment.

The argument number specifies the number of buffers to be allocated.
The NO BUFFERS command with appropriate keywords and argument restores
the default buffer values.
Dynamic Buffer Sizing
An optional global configuration command for adjusting huge buffer settings is
the BUFFERS HUGE SIZE command. As with the preceding command, use only
after consulting with Digital staff.
buffers huge size number
no buffers huge size number

Configuring the System 4–5

Configuring the System
Configuring the Global System Parameters
The BUFFERS HUGE SIZE command dynamically resizes all huge buffers to the
value that you supply. The buffer size cannot be lowered below the default. The
argument number specifies the number of buffers to be allocated.
The no version of the command with the keyword and argument restores the
default buffer values.

Examples
In the following example, the system will try to keep at least 50 small buffers
free.
buffers small min-free 50
In this example, the system will try to keep no more than 200 medium buffers
free.
buffers medium max-free 200
With the following command, the system will try to create one large temporary
extra buffer, just after a reload:
buffers large initial 1
In this example, the system will try to create one permanent huge buffer:
buffers huge permanent 1
In this example, the system will resize huge buffers to 20000 bytes:
buffers huge size 20000
To display statistics about the buffer pool on the router, enter the command
SHOW BUFFERS. For more information, refer to the section Monitoring System
Processes in Chapter 6.

Setting Configuration File Specifications
This section describes the BOOT global configuration commands used to configure
boot files. The BOOT command can be used to perform the following tasks:
•

Change default filenames.

•

Specify a server host for netbooting configuration files.

•

Specify the size buffer to configure for netbooting a host or network
configuration file.

The commands to load files over the network take effect the next time the
software is reloaded, provided they have been written into nonvolatile memory.
Changing the Network Configuration Filename
The network configuration file contains commands that apply to all routers and
terminal servers on a network. The default name of this file is network-confg.
See the section Entering Configuration Mode in Chapter 2. To change the name
of this file, use the BOOT NETWORK global configuration command. The full
command syntax follows:
boot network filename [address]
no boot network filename [address]

4–6 Configuring the System

Configuring the System
Configuring the Global System Parameters
The keyword network changes the network configuration filename from networkconfg. The argument filename is the new name for the network configuration file.
If you omit the argument address, the router uses the default broadcast address
of 255.255.255.255. If you use address, you can specify a specific network host or
a subnet broadcast address.
Changing the Host Configuration Filename
The host configuration file contains commands that apply to one router in
particular. To change the host configuration filename, use the BOOT HOST
global configuration command. The full command syntax follows:
boot host filename [address]
no boot host filename [address]
The keyword host changes the host configuration filename to a name you specify
in the filename argument. The router uses its name to form a host configuration
filename. To form this name, the router converts its name to all lowercase letters,
removes all domain information, and appends "-confg." By default, the host
filename is router-confg.
Specifying a Boot File Buffer Size
To specify the size of the buffer to be used for netbooting a host or a network
configuration file, use the BOOT BUFFERSIZE global configuration command.
The full command syntax follows:
boot buffersize bytes
no boot buffersize bytes
The argument bytes specifies the size of the buffer to be used. By default, it is the
size of your nonvolatile memory (32k). There is no minimum or maximum size
that can be specified.
The EXEC commands WRITE TERMINAL and WRITE NETWORK use the
information specified by the BUFFERSIZE keyword when performing their
functions (see the section Entering Configuration Mode in Chapter 2 for more
information about these EXEC commands).
Configuring Multiple Instances of the Boot Commands
You can configure multiple instances of the BOOT commands. When issued, each
command is executed in order and thus can be used to begin a systematic search
or to build a specific list. For example, you can issue multiple BOOT commands
to build an ordered list of configuration file name and host address pairs. The
router scans this list until it successfully loads the appropriate network or host
configuration file or system boot image. In this example, the router looks first for
fred-confg on network 192.31.7.24 and, if it cannot load that file, then looks for
wilma-confg on network 192.31.7.19.
boot host /usr/local/tftpdir/fred-confg 192.31.7.24
boot host /usr/local/tftpdir/wilma-confg 192.31.7.19
Note
This example uses fictitious filenames; the syntax of these filenames
depends on the TFTP server from which you are loading the files.

Configuring the System 4–7

Configuring the System
Configuring the Global System Parameters
If the router cannot find either file, a background process tries at ten-minute
intervals (the default) to load one file or the other.
You can issue multiple instances of all variations of the BOOT command,
including the NO BOOT forms. This feature can be useful for removing
configuration files. To remove a configuration file name and host address pair
from the list, use the NO BOOT command syntax.

Storing and Booting System Software Using the Flash Memory
Some versions of the DECbrouter 90 feature build in flash memory, onto which
system software images can be stored, booted, and rewritten as necessary.
This permits fast and simple system software upgrades. Other versions of the
DECbrouter 90 use one-time programmable ROM, and require that you use
Digital Services for future software upgrades. DECbrouter 90 versions with
one-time programmable ROM memory will report errors when you attempt to
load the flash memory. The following sections apply only to routers with flash
memory.
The flash memory allows you to:
•

Copy the TFTP or MOP image to flash memory

•

Boot a router from flash memory either automatically or manually

•

Copy the flash memory image to a TFTP server

The flash memory’s features include the following:
•

It can be remotely loaded with multiple system software images through a
TFTP or MOP transfer.

•

The DECbrouter 90 system software image resides in the flash permanently.

•

It allows a router to be booted manually or automatically from a system
software image stored in flash memory.

•

It provides write protection against accidental erasure or reprogramming of
the flash memory.

Security Precautions
The flash memory provides write-protection against accidental erasure or
reprogramming of the flash memories. The system image stored in the flash
memory only can be changed from a privileged EXEC command session on the
console terminal, which offers system-wide security as well.
Flash Memory Configuration Overview
The following is an overview of how to configure your system to boot from flash
memory. This is not a step-by-step set of instructions; rather, it is an overview to
the process of using the flash capability.
1. Set your system to boot from ROM software (bootstrap mode).
2. Restore the system configuration, if necessary.
3. Copy the TFTP or MOP image to flash memories.
4. Configure from the terminal to automatically boot from the desired file in
flash memory.
5. Write your configuration to memory.

4–8 Configuring the System

Configuring the System
Configuring the Global System Parameters
6. Set your system to netboot from flash (requires configuration register change).
7. Power-cycle and reboot your system to ensure that all is working as expected
and that the configuration is stored in NVRAM.
The remainder of this section describes the configuration commands used with
the flash feature.
Verifying Installation and Displaying Flash ROM Statistics
The SHOW FLASH command displays the total amount of flash memory present;
any files that may currently exist in flash memory and their size, and the
amounts of Flash memory used and remaining.
The SHOW FLASH or SHOW FLASH ALL commands will display the names of
the system software images.
show flash
show flash all
The following shows sample output of the show flash command:
Chrysostom# show flash
4096K bytes of flash memory sized on embedded flash.
Flash: running from Flash. READ-ONLY
File name/status
0 flash
[2104184/4194304 bytes free/total]
Table 4–1 and Table 4–2 explain the SHOW FLASH fields.

Table 4–1 Show Flash Field Descriptions
Field

Description

Bytes of flash memory
sized on embedded flash

Total amount of flash memory present.

File

The position of the file within memory.

Name/status

The name of the file and whether it is deleted or invalidated.

The following shows sample output of the SHOW FLASH ALL command:
Chrysostom(boot)# show flash all
4096K bytes of flash memory sized on embedded flash.
Chip
socket code
bytes
name
0
E9
89A2 0x100000 INTEL 28F008SA
1
E20
89A2 0x100000 INTEL 28F008SA
2
E13
89A2 0x100000 INTEL 28F008SA
3
E25
89A2 0x100000 INTEL 28F008SA
Flash file directory:
File name/status
addr
length
fcksum ccksum
0 DEWBR
0x3000040 2090056 0x554C 0x554C
[2104184/4194304 bytes free/total]

Configuring the System 4–9

Configuring the System
Configuring the Global System Parameters
Note
The SHOW FLASH ALL command will show abbreviated output when
the DECbrouter 90 is not in the Bootstrap Mode. See "Copying the TFTP
Image to Flash Memory" for information on entering bootstrap mode.

Table 4–2 Show Flash All Field Descriptions
Field

Description

Bytes of flash memory sized on embedded
flash

Total amount of flash memory present on the
DECbrouter 90.

Chip, Socket

Number and location of ROM on the circuit
board.

Code

Vendor code.

Bytes

Size in hex bytes.

Name

Vendor name and part number.

Contains:

Files that may currently exist in flash memory
and their size. Also the amounts of flash
memory used and remaining.

[invalidated]
[deleted]

Flag that appears when a file is rewritten
(recopied) into flash memory, when a user
aborts, when a network times out, or when
there is a flash memory overflow.

Address

First byte in the raw file image.

Length

Length of the raw image in bytes.

fcksum
ccksum

Image checksums.

When you see the [invalidated] flag, a prompt will tell you that the identical file
already exists and that it will be invalidated. The first (now invalidated) copy of
the file is still present within flash memory, but it is rendered unusable in favor
of the newest version.
To eliminate any files from flash (invalidated or otherwise) and free up all
available memory space, the entire flash memory must be erased; individual
files cannot be erased from flash memory.
Both examples illustrate that the flash memory can store and display multiple,
independent software images (gsxx and tsyy) for booting itself or for TFTP serving
software for other products. This feature would be most useful for storing default
system software as a backup. These images also can be stored in compressed
format.
Entering the Bootstrap Mode
Before the flash ROM may be loaded from either the TFTP or MOP, the
DECbrouter 90 must be placed in bootstrap mode.
Flash ROM comes pre-loaded with the latest software. The user loads flash only
after receiving a software update. This requires a new software configuration
register setting and a router reboot. To put the DECbrouter 90 into bootstrap
mode, set bits 3-0 of the configuration register to 0001. This may be done with
the configuration command CONFIG-REGISTER or other methods described in

4–10 Configuring the System

Configuring the System
Configuring the Global System Parameters
the DECbrouter 90 Getting Started guide, the section Setting the Configuration
Register.
To upgrade firmware follow the steps below:
1. Enter bootstrap mode.
If you are using the default configuration register setting, you may use
the global configuration command CONFIG-REGISTER to change the
configuration register to 0x101. Otherwise refer to the DECbrouter 90 Getting
Started guide, the section Setting the Configuration Register for instructions
on reading, interpreting, and modifying the configuration register. (In effect,
setting the boot field of the configuration register involves changing the
rightmost hex digit of the register value to a 1.)
Note
After loading the flash image, return to booting from flash (exit bootstrap
mode); write 0x102 to the configuration register (set the boot field to flash)
and reboot.

2. Reinitialize or reboot the router to enter the bootstrap mode. In bootstrap
mode the DECbrouter 90 prompts will consist of: router name(boot)>.
3. Put the router in enabled mode by issuing the ENABLE command. The
router must be in enabled mode before the flash can be loaded.
From this mode you may load the flash ROM or do a show flash all for
complete flash data.
4. Use the copy tftp flash or copy mop flash commands to load the new code.
5. Set the configuration register to boot the flash code by setting the boot field
to 2. For the default configuration, the configuration register value would be
0x102.
6. Reinitialize or reboot. The router will now boot the new code.

Example
The following example will configure the router for bootstrap mode and then
reboot it for flash loading.
Chrysostom>enable
Password:
Chrysostom#configure terminal
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
config-register 0x101
^Z
Chrysostom#
%SYS-5-CONFIG_I: Configured from console by console ()
Chrysostom#reload
[confirm]

Configuring the System 4–11

Configuring the System
Configuring the Global System Parameters
%SYS-5-RELOAD: Reload requested
System Bootstrap, Version 4.6
Copyright (c) 1986-1992 by cisco Systems
2000 processor with 1024 Kbytes of main memory
Restricted Rights Legend
Use, duplication, or disclosure by the Government is
subject to restrictions as set forth in subparagraph
(c) of the Commercial Computer Software - Restricted
Rights clause at FAR sec. 52.227-19 and subparagraph
(c) (1) (ii) of the Rights in Technical Data and Computer
Software clause at DFARS sec. 252.227-7013.
Cisco Systems, Inc.
1525 O’Brien Drive
Menlo Park, California 94025
3000 Software (IGS-RXBOOT Bootstrap), Version 9.14
Copyright (c) 1986-1992 by cisco Systems, Inc.
Compiled Tue 03-Nov-92 14:41
DECbrouter 90 (68030) processor (revision 0x00) with 1024K/1024K bytes of
memory.
Processor board serial number 00000000
DDN X.25 software.
1 Ethernet/IEEE 802.3 interface.
2 Serial network interface.
32K bytes of non-volatile configuration memory.
4096K bytes of flash memory sized on embedded flash.
Press RETURN to get started!
Chrysostom(boot)>enable
Password:
Chrysostom(boot)#

Example
The following example configured the router to return to booting flash after
loading the flash ROM.
Chrysostom(boot)#configure terminal
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
config-register 0x102
^Z
Chrysostom#
%SYS-5-CONFIG_I: Configured from console by console ()
Chrysostom#reload
[confirm]
%SYS-5-RELOAD: Reload requested

4–12 Configuring the System

Configuring the System
Configuring the Global System Parameters
Copying the TFTP Image to Flash Memory
The COPY TFTP FLASH command copies (writes) a TFTP image into the current
flash configuration:
copy tftp flash

Caution
Do not enter a WRITE MEMORY command while in the bootstrap mode.
The bootstrap code does not understand all the configuration commands
and will corrupt your NVRAM configuration if you attempt to write it out
in bootstrap mode. Make all configuration changes in flash mode.

Note
While the flash supports loading multiple files into flash memory, normal
software images usually exceed 2 megabytes in size, making it impossible
to load one of them in a DECbrouter 90 with only 4 megabytes of flash
memory. Therefore, when loading a full image, you should request that
the COPY TFTP FLASH command erase the flash before the load. If,
however, there is some question about if a new image can fit without
erasing the existing images, use the SHOW FLASH command and
compare the size of the file you wish to copy to the amount of available
flash memory shown. If the space available is less than the space required
by the file you wish to copy, the copy process will continue, but the entire
file will not be copied into flash. A failure message, buffer overflow xxxx/xxxx, will appear, where xxxx/xxxx is the number of bytes read in
/number of bytes available.
Once you issue the COPY TFTP FLASH command, the system prompts you for
the IP address (or domain name) of the TFTP server. This may be another router
serving ROM or flash system software images. You are then prompted for the
file name of the software image and given the option to erase the existing flash
memory before writing onto it only when there is free space available in Flash
memory. If no free flash memory space is available, the erase routine is required
before new files can be copied. The system will be prompt you for these conditions.
The flash memory is loaded with the system software image at the factory before
shipment.
Following is sample output (copying a system image named gsxx) of the prompt
you will see under these conditions:
Chrysostom(boot)# copy tftp flash
IP address or name of remote host [255.255.255.255]?
131.131.101.101
Name of tftp filename to copy into flash []? gsxx
copy gsxx from 131.131.101.101 into flash memory? [confirm]
Flash is filled to capacity. (This line only appears if
Flash memory is full.)
Erasure is needed before flash may be written.
Erase flash before writing? [confirm]

Configuring the System 4–13

Configuring the System
Configuring the Global System Parameters
Note
Entering n after the "Erase flash before writing?" prompt would continue
the copy process. Entering a y would proceed with the erase routine.
Make certain you have ample flash memory space before entering n at the
erasure prompt.
When you erase the existing flash, the system clears and initializes each flash
memory and displays a pound sign (#) prompt for each cleared and initialized
device (total of 16). The entire copying process takes several minutes and will
differ from network to network.
Note
The file name gsxx can be in either lower- or uppercase; the system will
see GSxx as gsxx. If both are copied to flash, the second file copied will
become the valid file.
Following is sample output from copying a system image named gsxx into the
current flash configuration:
Chrysostom(boot)# copy tftp flash
IP address or name of remote host [255.255.255.255]? 131.131.
101.101
Name of tftp filename to copy into flash []? gsxx
copy gsxx from 131.131.101.101 into flash memory?[confirm]
xxxxxxxx bytes available for writing without erasure.
erase flash before writing? [confirm]
Clearing and initializing flash memory (please wait)01/02/03/04/05/06/07/08
/09/10/11/12/13/14/15
Loading from 101.2.13.110: !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!... [OK - 324572/524212 bytes]
Verifying checksum...
vvvvvvvvvvvvvvvvvvvvvvvv
Flash verification successful. Length = 324572, checksum = 0xE2E2
Note
To abort this copy process, press the Ctrl, Shift, and 6 keys
simultaneously. Although the process will abort, the partial file copied
before the abort was issued will remain until the entire Flash memory is
erased.
The series of exclamation points (!) in the previous sample output indicates that
the copying process is taking place. The series of v’s indicates that a checksum
verification of the flash memory is occurring as it is loaded into memory for boot.
Checksum verification occurs only through data compare during programming of
the flash memory. The last line in the sample configuration indicates that the
copy is successful.

4–14 Configuring the System

Configuring the System
Configuring the Global System Parameters
Having successfully copied an image onto the flash, the output of show flash all
will provide the image name, as in the following sample output:
Chrysostom(boot)#sho flash all
4096K bytes of flash memory sized on embedded flash.
Chip Socket Code
Bytes
Name
0
E9
89A2 0x100000 INTEL 28F008SA
1
E20
89A2 0x100000 INTEL 28F008SA
2
E13
89A2 0x100000 INTEL 28F008SA
3
E25
89A2 0x100000 INTEL 28F008SA
Flash file directory:
File name/status
addr
length fcksum ccksum
0 f
0x3000040 2090056 0x554c 0x554c
[2104184/4194304 bytes free/total]
You are now ready to boot from flash. The following sections describe how to
automatically and manually boot from flash memory.
Copying the MOP Image to Flash Memory
New releases of the system image may also be loaded from VMS using the MOP
protocol. The software must be ready to load from a local MOP VMS router. The
procedure is similar to loading a TFTP image. As in loading the TFTP image,
you must be in bootstrap mode to load the flash. See the previous section for
instructions on loading the flash.
The command for MOP loading the flash is COPY MOP FLASH. You will be
prompted for the file name. As with the TFTP flash load, you are given an option
to erase existing flash memory before writing onto it. The system then clears
and initializes each flash memory. A pound sign (#) prompt is displayed for each
cleared and initialized device (16 total). The entire copy process takes several
minutes and will differ from network to network.
The following example shows sample output of copying a system image, which is
named DEWBR, into the current flash configuration.
Example

Router(boot)#copy mop flash
File name/status
0 DEWBR
[2243008/4194304 bytes free/total]
Name of file to copy ? DEWBR
Copy DEWBR from MOP server into flash memory ? [confirm]
2242944 bytes available for writing without erasure
Erase flash before writing? [confirm]
Flash erase: erasing bank 0 ..
00/01/02/03/04/05/06/07/08/09/10/11/12/13/14/15/
Mope2flash: Loading DEWBR into flash from aa00.0400.d116 on Ethernet0:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! [OK - 1648952/4194176 bytes]
Verifying via checksum...
vvvvvvvvvvvvvvvvvvvvvvvvvvvv
Verification successful: Length = 1951232, checksum = 0xEFF1
The series of pound signs (#) indicate each flash device is being cleared and
Configuring the System 4–15

Configuring the System
Configuring the Global System Parameters
initialized; one per device (16 total). The last line in the sample configuration
indicates that the copy is successful.
The exclamation points indicate the copy process.
The series of Vs in the above sample output indicates that a checksum verification
of the Flash is occurring as it is loaded into memory for boot. It is verified only
through data compare during programming of the flash.
Note
Should you wish to abort this copy process, press the Ctrl, Shift, and
6 keys simultaneously. The process will abort; however, the data that
was copied before the abort was issued, will remain until the entire flash
memory is erased. Individual files cannot be erased from flash memories.
If the TFTP image is too large, the following failure message appears:
buffer overflow - xxxx/xxxx
The value xxxx/xxxx is the number of bytes read in/number of bytes available.
Use the output of show flash all to obtain the image name. See Verifying
Installation and Displaying Flash ROM Statistics in this chapter for more
information about this EXEC command.
Once you have configured flash memory, you are now ready to boot from
flash. See Automatically Booting from Flash Memory in this chapter for more
information. You can also manually boot from the ROM monitor using the B
FLASH command. See Manually Booting from Flash Memory in this chapter for
more information.
Automatically Booting from Flash Memory
In most situations, you will want the router configured to automatically boot the
flash memory every time it reboots. (The other options are to boot the bootstrap
code or enter the monitor.) This is accomplished by setting the boot field of the
configuration register to boot from flash.
The section "Setting the Configuration Register" in the DECbrouter 90 Getting
Started guide describes complete instructions on setting the processor register.
The easiest way to set the configuration register is by using the CONFIGREGISTER global configuration command.
To configure the register to automatically boot from flash, use the SHOW
VERSION command first to get the current hexadecimal value of the
configuration register:
Chrysostom#show version
3000 Software (DEWBR), Version 9.14
Copyright (c) 1986-1992 by Cisco Systems, Inc.
Compiled Tue 02-Feb-93 14:32
System Bootstrap, Version 4.6
Chrysostom uptime is 1 day, 21 hours, 24 minutes
System restarted by reload
System image file is "DEWBR", booted via flash

4–16 Configuring the System

Configuring the System
Configuring the Global System Parameters
DECbrouter 90 router (68030) processor (revision 0x00) with 1024K/1024K
bytes of memory.
Processor board serial number 00000000
DDN X.25 software, Version 2.0.
Bridging software.
SuperLAT software (copyright 1990 by Meridian Technology Corp).
1 Ethernet/IEEE 802.3 interface.
2 Serial network interface.
32K bytes of non-volatile configuration memory.
4096K bytes of flash memory sized on embedded flash.
Configuration register is 0x101
Chrysostom#
The "configuration register" line shows the current hexadecimal value. The boot
field is represented by the rightmost hex digit. Change this digit to the value 2
("Boot from flash," see the descriptions of all the values in the DECbrouter 90
Getting Started guide, and write the new configuration register value with the
CONFIG-REGISTER configuration command:
Chrysostom# config terminal
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
config-register 0x102
^Z
Upon reboot, the configuration register value will take effect, and the router will
automatically boot from flash upon initialization.
Refer to the DECbrouter 90 Getting Started guide for more information on the
configuration register and various boot modes.
Manually Booting from Flash Memory
Use the B FLASH command at the ROM monitor level to manually boot the
system, as in the following example. Check the DECbrouter 90 Getting Started
guide for the correct configuration register setting.
>b flash
F3: 1578668+35572+156084 at 0x30000060
{ROM Monitor copyrights...}
Copying the Flash Memory Image to a TFTP Server
To copy an image back to a TFTP server, use the COPY FLASH TFTP command.
This copy of the system image can serve as a backup copy and can also be used to
verify that the copy in Flash is the same as on the original file on disk.
copy flash tftp
The following is an example of the use of this system configuration command:
Chrysostom# copy flash tftp
IP address of remote host [255.255.255.255]? 101.2.13.110
Name of file to copy []? gsxx
writing gsxx !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Chrysostom#
Note
A domain name can be used in place of the IP address of the remote host.

Configuring the System 4–17

Configuring the System
Configuring the Global System Parameters

Configuring Flash Memory as a TFTP Server
The DECbrouter 90 can be used as a trivial file transfer protocol (TFTP) file
server for other routers on the network. This feature allows you to load system
software into the Flash of other DECbrouter 90s from a pre-loaded DECbrouter
90. This may be useful for mass software upgrades.
For clarification in the description that follows, one router (with flash memory)
will be referred to as the flash server and all other routers will be referred to as
client routers. The configurations for the flash server router will be given through
example configurations, with commands included as necessary. After the flash
server is configured, the client router may be loaded using the "Copying TFTP
image to flash memory" instructions; use the flash server address as the TFTP
server.
Prerequisites
The flash server and client router must be able to reach one another before the
TFTP function can be implemented. Verify this connection by using the PING
command to move between the flash server and client router (in either direction).
An example use of the PING command is as follows:
Router# ping 131.131.101.101 <Return>
In this example, the internet protocol (IP) address of 131.131.101.101 belongs
to the client router. Connectivity is indicated by !!!!!, while ... [timed out] or
[failed] indicates none. If the connection fails, reconfigure the interface, check the
physical connection between the flash server and client router, and issue PING
again.
After this connection is verified, use the SHOW FLASH command to locate the
file name of the boot image present in the flash memory of the flash server. You
will need this file name to TFTP load the client router. The next example uses
the file name gs3-bfx..91.1 for the boot image.
Once you have the file name of the boot image in flash memory, you can configure
the flash server.
Configuring the Flash Server
Configure the flash server by adding both the TFTP-SERVER SYSTEM
command and the ACCESS-LIST command to the configuration memory. Use
the CONFIGURE-TERMINAL command to do so.
Following is sample output of these commands:
Server# configure terminal
Enter configuration commands, one per line.
Edit with DELETE, CRTL/W, and CRTL/U; end with CTRL/Z
tftp-server system gs3-bfx.91.1 1
access-list 1 permit 131.131.101 0.0.0.255
^Z
Server# write memory <Return>
[ok]
Server#
This example gives the file name of the software image in the flash server and one
access list (labeled 1). The access list must include the network within which the
client router resides. Thus, in the example, the network 131.131.101.0 and any
client routers on it are permitted access to the flash server, file name gs3-bfx.91.1.

4–18 Configuring the System

Configuring the System
Configuring the Global System Parameters
For more information on access lists, refer to the DECbrouter 90T Products,
Configuration and Reference, Volume 2, Chapter 5, "IP Routing."
Caution
Using the no boot system command in the following example will
invalidate all other boot system commands currently in the client router
system configuration. Before proceeding, determine whether the system
configuration stored in the router you will use as the client should first be
saved (uploaded) to a TFTP file server. Refer to Chapter 2 for instructions
on uploading and downloading system configuration files.

Establishing Passwords and System Security
This section describes how to configure password protection and terminal access
security.
You can set passwords to control access to the privileged command level and to
individual lines. The terminal access controller access control system (TACACS)
protocol controls terminal use by means of a user-ID-and-password pair. The
Defense Data Network (DDN) developed TACACS to control access to its TAC
terminal servers; the DECbrouter 90 TACACS support is patterned after the
DDN application.
These system security measures may not provide the level of protection needed
for some environments; individual routing protocols and bridging support may
have additional security procedures. You also may need to use access lists for
additional protection. For access list configuration procedures, refer to the
sections describing configuration of a particular routing protocol or bridging
support.

Establishing the Privileged-Level Password
To assign a password for the privileged command level, use the ENABLE
PASSWORD global configuration command.
enable password password
The argument password is case-sensitive and specifies the password prompted
for in response to the EXEC command ENABLE. The password argument can
contain any alphanumeric characters, including spaces, up to 80 characters.
Password checking is also case-sensitive. The password Secret is different from
the password secret, for example, and the password two words is an acceptable
password.
To enter the privileged command level, enter the following EXEC command and
then press Return:
enable
Next, enter the password for the privileged command level at the Password:
prompt.

Configuring the System 4–19

Configuring the System
Establishing Passwords and System Security
When you use the ENABLE command at the console terminal, the EXEC will
not prompt for a password if the privileged mode password is not set. This
feature allows access to the CONFIGURE command to enter configuration
command collection mode, so you can set parameters—such as the password for
the privileged command level—for other lines. To restrict access to the console
line, set a line password as described in the section Establishing Line Passwords
later in this chapter.

Example
The following example sets the password secretword for the privileged command
level on all lines, including the console:
enable-password secretword
Specifying a Password
When an EXEC is started on a line with password protection, the EXEC prompts
for the password. If you enter the correct password, the EXEC prints its normal
nonprivileged prompt. You can try three times to enter a password before the
EXEC exits and returns the terminal to the idle state.
To specify a password, use the PASSWORD line subcommand. The full command
syntax follows:
password text
no password
The text argument can contain any alphanumeric character, including spaces, up
to 80 characters. The password checking is also case-sensitive. The password
Secret is different than the password secret, for example, and the password two
words is an acceptable password.
To enable checking for the password specified by the PASSWORD command, use
the line subcommand LOGIN:
login
Alternatively, to use the TACACS user ID and password-checking mechanism, use
the following subcommand:
login tacacs
To disable all password checking, use the following command:
no login
The server prints the message-of-the-day banner before prompting for a password,
so you immediately see messages such as no trespassing notifications. By default,
virtual terminals require a password. If you do not set a password for a virtual
terminal, it will respond to attempted connections by displaying an error message
and closing the connection. Use the NO LOGIN subcommand to disable this
behavior and allow connections without a password.

4–20 Configuring the System

Configuring the System
Establishing Passwords and System Security
Example
The following example sets the password letmein on line 5:
line 5
password letmein
login
Recovering from a Lost Password
It is possible to lock yourself out if you enable password checking on the console
terminal line and then forget the line password.
To recover from this situation, force the DECbrouter 90 into factory diagnostic
mode. Set bit 7 of the processor configuration register from the monitor and
reboot the DECbrouter 90. (See DECbrouter 90 Getting Started guide, the section
Setting the Configuration Register.) Follow these steps:
1. You will be asked if you want to set the manufacturers’ addresses. Respond
by typing yes. You then see the following prompt:
TEST-SYSTEM>
2. Enter the ENABLE command to get the privileged prompt, as in:
TEST-SYSTEM# enable
3. Enter the SHOW CONFIGURATION command to review the system
configuration and find the password.
4. To resume normal operation, set bit 7 of the configuration register to zero,
and reboot the router. (You may use the CONFIG-REGISTER configuration
command to do this.)
5. Log in to the router with the password that was shown in the configuration
file.
The processor configuration registers are described in the DECbrouter 90 Getting
Started guide.
When the router restarts in factory diagnostic mode, it does not read the
nonvolatile memory, thus avoiding the command to set a password for the console
terminal. Do not change any router configuration in the factory diagnostic mode.
Note
All debugging capabilities are turned on during diagnostic mode.

Encrypting Passwords
You can increase access security to your router by encrypting passwords. When
password encryption is enabled, the encrypted forms of the passwords are
displayed when a SHOW CONFIG command is entered. Use the SERVICE
PASSWORD-ENCRYPTION global configuration command:
service password-encryption
no service password-encryption
The actual encryption process occurs when the current configuration is written
or when a password is configured. Password encryption can be applied to both

Configuring the System 4–21

Configuring the System
Establishing Passwords and System Security
the privileged command password and to console and virtual terminal line access
passwords. See the section Establishing Line Passwords later in this chapter.
Note
It is not possible to recover a lost encrypted password.

Example
The following example causes no encryption to take place:
gw# config
service password-encryption
no service password-encryption
The next example encrypts the privileged command password secret. Additional
passwords are not encrypted. The encrypted password remains in its encrypted
form until it is reconfigured with a nonencrypted password:
gw# config
service password-encryption
enable-password secret
no service password-encryption
If you modify a configuration file and add a SERVICE PASSWORDENCRYPTION configuration command, when you write the configuration file
all passwords will become encrypted.

Establishing Terminal Access Control
DECbrouter 90 provides unsupported versions of both a standard and an
extended TACACS server. The servers run on most UNIX systems and are
available via FTP from the host. You can use the servers to create UNIX
accounting applications that monitor use of a system and user logins.
The configuration commands in the following sections tailor the behavior of the
standard TACACS server.
Setting the Server Host Name
The TACACS-SERVER HOST global configuration command specifies a TACACS
host. The full syntax of this command follows.
tacacs-server host name
no tacacs-server host name
The argument name is the name or Internet address of the host. You can use
multiple TACACS-SERVER HOST subcommands to specify multiple hosts. The
server will search for the hosts in the order you specify them. The NO TACACSSERVER HOST global configuration command deletes the specified name or
address.

4–22 Configuring the System

Configuring the System
Establishing Passwords and System Security
Limiting Login Attempts
The TACACS-SERVER ATTEMPTS global configuration command controls
the number of login attempts that can be made on a line set up for TACACS
verification.
tacacs-server attempts count
no tacacs-server attempts
The argument count is the number of attempts. The default is three attempts.
The NO TACACS-SERVER ATTEMPTS global configuration command restores
the default.

Example
This command changes the login attempt to just one try:
!
tacacs-server attempts 1
!
Controlling Retries
The TACACS-SERVER RETRANSMIT global configuration command specifies
the number of times the server will search the list of TACACS server hosts before
giving up. The server will try all servers, allowing each one to time out before
increasing the retransmit count.
tacacs-server retransmit retries
no tacacs-server retransmit
The argument retries is the retransmit count. The default is two retries.
The NO TACACS-SERVER RETRANSMIT global configuration command restores
the default.

Example
This command specifies a retransmit counter value of five times:
!
tacacs-server retransmit 5
!
Setting the Timeout Intervals
The TACACS-SERVER TIMEOUT global configuration command sets the interval
that the server waits for a server host to reply.
tacacs-server timeout seconds
no tacacs-server timeout
The argument seconds specifies the number of seconds. The default interval
is five seconds. The NO TACACS-SERVER TIMEOUT global configuration
command restores the default.

Configuring the System 4–23

Configuring the System
Establishing Passwords and System Security
Example
This command changes the interval timer to ten seconds:
!
tacacs-server timeout 10
!
Setting the Last Resort Login Feature
If, when running the TACACS server, it does not respond, the default action is to
deny the request. Use the TACACS-SERVER LAST-RESORT global configuration
command to change the default.
tacacs-server last-resort {password | succeed}
no tacacs-server last-resort {password | succeed}
The command causes the router to request the privileged password as verification,
or forces successful login without further input from the user, depending upon the
keyword specified, as follows:
•

PASSWORD—Allows the user to access the privileged-level command mode
by entering the password set by the ENABLE command.

•

SUCCEED—Allows the user to access the privileged-level command mode
without further question.
Note
The last resort login feature can be useful when it is important to be able
to ensure that login can occur. An example of such a condition is when a
system administrator needs to log in to troubleshoot TACACS servers that
are down.

The NO TACACS-SERVER LAST-RESORT global configuration command
restores the system to the default behavior.

Establishing Privileged-Level TACACS
The following variations of the ENABLE command can be used to configure
privileged-level command access using the TACACS protocol.
Enabling the Privileged Mode
The ENABLE USE-TACACS global configuration command is used for setting the
TACACS protocol to determine whether a user can access the privileged command
level.
enable use-tacacs
no enable use-tacacs
If you use this command, the EXEC ENABLE command will ask for both a new
user name and a password. This information is then passed to the TACACS
server for authentication. If you are using the extended TACACS, it will also pass
any existing UNIX user identification code to the server.

4–24 Configuring the System

Configuring the System
Establishing Passwords and System Security
Note
When used without extended TACACS, this command allows anyone with
a valid user name and password to access the privileged command level,
creating a potential security problem. This is because the TACACS query
resulting from entering the ENABLE command is indistinguishable from
an attempt to log in without extended TACACS.

Enabling the Privileged Mode Last Resort Login Feature
The ENABLE LAST-RESORT global configuration command allows you to specify
what happens if the TACACS servers used by the ENABLE command do not
respond.
enable last-resort {password | succeed}
no enable last-resort {password | succeed}
The default action is to fail. Use of the keyword changes the action, as follows:
•

PASSWORD—Allows you to enable by entering the privileged command level
password.

•

SUCCEED—Allows you to enable without further question.

The NO ENABLE LAST-RESORT global configuration command restores the
default.

Configuring TACACS Accounting
The following sections describe the configuration commands that tailor the
behavior of the extended TACACS client.
Enabling Extended TACACS Mode
The TACACS-SERVER EXTENDED global configuration command enables an
extended TACACS mode.
tacacs-server extended
no tacacs-server extended
This mode provides information about the terminal requests for use in setting
up host auditing trails and accounting files for tracking use of terminal servers
and routers. Information includes responses from terminal servers and routers
and validation of user requests. An unsupported, extended TACACS server is
available from Cisco Systems via anonymous FTP (ftp.cisco.com) for UNIX users
who want to create the auditing programs.
The NO TACACS-SERVER EXTENDED command disables this mode.

Configuring the System 4–25

Configuring the System
Establishing Passwords and System Security
Login Notification
The TACACS-SERVER NOTIFY global configuration command causes a message
to be transmitted to the TACACS server, with retransmission being performed by
a background process for up to five minutes. The terminal user, however, receives
an immediate response allowing access to the terminal. The full syntax of this
command follows.
tacacs-server notify {connect | enable | logout}
no tacacs-server notify {connect | enable | logout}

The keywords specify notification of the TACACS server whenever a user does
one of the following:
•

connect—Makes TCP connections

•

enable—Enters the ENABLE command

•

logout—Logs out

The NO TACACS-SERVER NOTIFY command used with the appropriate keyword
disables notification.
Note
When used with extended TACACS, the command TACACS-SERVER
NOTIFY ENABLE allows anyone with a valid user name and password to
access the privileged-level command mode.

Login Authentication
The TACACS-SERVER AUTHENTICATE command requires a response from the
network or communication server to indicate whether the user may perform the
indicated action.
tacacs-server authenticate {connect | enable}
no tacacs-server authenticate {connect | enable}
Actions that require a response include the following, specified as optional
keywords:
•

connect—Makes TCP connections

•

enable—Enters the ENABLE command

The NO TACACS-SERVER AUTHENTICATE command used with the
appropriate keyword disables the action.
Optional Password Verification
You can specify that the first TACACS request to a TACACS server is made
without password verification. This option is configured with the TACACSSERVER OPTIONAL-PASSWORDS global configuration command.
tacacs-server optional-passwords
When the user enters the login name, the login request is transmitted with the
name and a zero-length password. If accepted, the login procedure completes.

4–26 Configuring the System

Configuring the System
Establishing Passwords and System Security
If the TACACS server refuses this request, the terminal server prompts for a
password and tries again when the user supplies a password. The TACACS
server must support authentication for users without passwords to make use of
this feature. This feature supports all TACACS requests, such as login, SLIP, and
enable.

Authenticating User Names
Networks that cannot support a TACACS service still may wish to use a user
name-based authentication system. In addition, it may be useful to define certain
user names that get special treatment (for example, an "info" user name that does
not require a password, but connects the user to a general-purpose information
service).
The router software supports these needs by implementing a local USERNAME
configuration command. The format for the command is as follows:
username name [nopassword | password encryptiontype password]
username name [accesslist number]
username name [autocommand command]
username name [noescape] [nohangup]
Multiple USERNAME commands can be used to specify options for a single user.
The nopassword keyword means that no password is required for this user
to log in. This is usually most useful in combination with the autocommand
keyword.
The password keyword specifies a possibly encrypted password for this user
name.
The encryptiontype argument is a single-digit number. Currently defined
encryption types are 0, which means no encryption, and 7, which specifies a
DECbrouter 90-defined encryption algorithm. Passwords entered unencrypted are
written out with the DECbrouter encryption. A password can contain embedded
spaces and must be the last option specified in the USERNAME command.
The accesslist keyword specifies an outgoing access list that overrides the access
list specified in the access class line configuration subcommand. It is used for
the duration of the user’s session. The access list number is specified by the
number argument.
The autocommand keyword causes the command specified by the command
argument to be issued automatically after the user logs in. When the command is
complete, the session is terminated. Because the command can be any length and
contain embedded spaces, commands using the autocommand keyword must be
the last option on the line.
The noescape keyword prevents using an escape character on the host to which
the user is connected.
The nohangup keyword prevents the router from disconnecting the user after
an automatic command (set up with the autocommand keyword) has completed.
Instead, the user gets another login prompt.

Configuring the System 4–27

Configuring the System
Establishing Passwords and System Security
Examples
To implement a service similar to the UNIX WHO command, which can be given
at the login prompt and lists the current users of the router, the command takes
the following form:
username who nopassword nohangup autocommand show users
To implement an ID that will work even if all the TACACS servers break, the
command is as follows:
username superuser password superpassword

Configuring the Simple Network Management Protocol (SNMP)
The simple network management protocol (SNMP) provides a way to access and
set configuration and run-time parameters for the router. The DECbrouter 90
implementation of SNMP is compatible with RFCs 1155, 1156, and 1157. The
management information base (MIB) supports RFCs 1155 to 1213 and provides
DECbrouter 90-specific variables.
A separate document, available in RFC 1213-type (MIB II) format, describes
all the DECbrouter 90-specific SNMP variables in the Digital portion of the
MIB. It also describes what is required to establish minimum configuration.
Contact Digital to obtain a copy of this document, which includes instructions for
accessing the variables using SNMP.

Enabling and Disabling the SNMP Server
To configure the SNMP server, you need to be in the configuration command
collection mode. Enter this mode using the EXEC command CONFIGURE at the
EXEC prompt. See the section Entering Configuration Mode in Chapter 2 of this
manual for a description of the procedure.
Begin SNMP operation by entering the configuration commands that define the
desired operation. To disable SNMP server operations on the DECbrouter 90 after
it has been started, use the NO SNMP-SERVER global configuration command.
no snmp-server

Defining the SNMP Server Access List
To set up an access list that determines which hosts can send requests to the
router, use the SNMP-SERVER ACCESS-LIST global configuration command.
This access list applies only to the global read-only SNMP agent configured
with the command SNMP-SERVER COMMUNITY. The DECbrouter 90 ignores
packets from hosts that the access list denies.
The full command syntax follows.
snmp-server access-list list
no snmp-server access-list list
The argument list is an integer from 1 through 99 that specifies an IP access list
number.
The NO SNMP-SERVER ACCESS-LIST global configuration command removes
the specified access list.

4–28 Configuring the System

Configuring the System
Configuring the Simple Network Management Protocol (SNMP)
Example
This command causes the router to ignore packets from hosts that do not match
access list 21:
!
snmp-server access-list 21
!

Setting the Community String
To set up the community access string, use the SNMP-SERVER COMMUNITY
global configuration command. The full command syntax follows.
snmp-server community string [RO | RW] [list]
no snmp-server community [string] [RO | RW] [list]
This command enables SNMP server operation on the DECbrouter 90. The
argument string specifies a community string that acts like a password and
permits access to the SNMP protocol.
By default, an SNMP community string permits read-only access (keyword RO);
use the keyword RW to allow read-write access. The optional argument list is an
integer from 1 through 99 that specifies an access list of Internet addresses that
can use the community string.
The NO SNMP-SERVER COMMUNITY global configuration command removes
the specified community string or access list.

Example
This command assigns the string comaccess to the SNMP server, allows read-only
access, and specifies that addresses that match the criteria in access list 4 can
use the community string. (Notice that the string is entered without quotes or
any other parsing characters.)
snmp-server community comaccess RO 4

Note
Neither the console password nor the enabled-mode password can be used
as the community string.

Establishing the Message Queue Length
To establish the message queue length for each TRAP host, use the SNMPSERVER QUEUE-LENGTH global configuration command.
snmp-server queue-length length
no snmp-server queue-length
This command defines the length of the message queue for each TRAP host.

Configuring the System 4–29

Configuring the System
Configuring the Simple Network Management Protocol (SNMP)
The argument length is the number of TRAP events that can be held before the
queue must be emptied; the default is 10. Once a TRAP message is successfully
transmitted, software will continue to empty the queue, but never faster than at
a rate of four TRAP messages per second.
The NO SNMP-SERVER QUEUE-LENGTH command resets the queue length to
its default value of 10.

Example
This command establishes a message queue that traps four events before it must
be emptied:
snmp-server queue-length 4

Establishing Packet Filtering
To establish the packet filtering size, use the SNMP-SERVER PACKETSIZE
global configuration command. The full command syntax follows.
snmp-server packetsize bytes
no snmp-server packetsize
This command allows control over the largest SNMP packet size permitted when
the SNMP server is receiving a request or generating a reply.
The argument bytes is a byte count from 484 through 8192. The default is 484.
The NO SNMP-SERVER PACKETSIZE command resets this default.

Example
This command establishes a packet filtering maximum size of 1024 bytes:
snmp-server packetsize 1024

Establishing the TRAP Message Recipient
To specify the recipients of TRAP messages, use the SNMP-SERVER HOST global
configuration command. The full syntax follows.
snmp-server host address community-string [snmp | tty]
no snmp-server host address community-string
This command specifies which host or hosts should receive TRAP messages. You
need to issue the SNMP-SERVER HOST command once for each host acting as a
TRAP recipient.
The argument address is the name or Internet address of the host. The argument
community-string is the password-like community string set with the SNMPSERVER COMMUNITY command.
The optional keywords define whether the TRAPS be included, as follows:
•

snmp—Causes all SNMP-type TRAP messages to be sent and starts the
DECbrouter 90-specific RELOAD TRAP message.

4–30 Configuring the System

Configuring the System
Configuring the Simple Network Management Protocol (SNMP)
•

tty—Causes TCP connection TRAP messages to be included.

With the SNMP-SERVER HOST command, you get all the SNMP TRAP messages
about TTY events by default. The NO SNMP-SERVER HOST command removes
the specified host.

Examples
This command sends all possible SNMP TRAPS to 131.108.2.160, including TTY
TRAPS.
snmp-server host 131.108.2.160
In order to turn these TRAP messages off, use the NO SNMP-SERVER HOST
command. For example, the sequence of commands that follows sends only the
seven SNMP TRAP messages to 131.108.2.160, not all the others.
snmp-server host 131.108.2.160
no snmp-server host 131.108.2.160 tty
This example causes all the SNMP-type messages to be sent to the host specified
by the name gatekeeper.dec.com. The command uses the community string
comaccess as the password:
snmp-server host gatekeeper.dec.com comaccess snmp

Establishing TRAP Message Authentication
To establish the TRAP message authentication, use the SNMP-SERVER TRAPAUTHENTICATION global configuration command.
snmp-server trap-authentication
no snmp-server trap-authentication
This command enables the DECbrouter 90 to send a TRAP message when it
receives a packet with an incorrect community string.
The SNMP specification requires that a TRAP message be generated for each
packet with an incorrect community string. However, because this action can
result in a security breach, the router by default does not return a TRAP message
when it receives an incorrect community string.

Establishing the TRAP Message Timeout
To define how often to try resending TRAP messages on the retransmission
queue, use these global configuration commands:
snmp-server trap-timeout seconds
no snmp-server trap-timeout
The argument seconds sets the interval for resending the messages. The default
is set to 30 seconds. The NO SNMP-SERVER TRAP-TIMEOUT command
restores this default.

Configuring the System 4–31

Configuring the System
Configuring the Simple Network Management Protocol (SNMP)
Example
This command sets an interval of 20 seconds to try resending TRAP messages on
the retransmission queue:
snmp-server trap-timeout 20

Enabling SNMP System Shutdown Feature
Using SNMP packets, a network management tool can send messages to users on
virtual terminals and on the DECbrouter 90 console. The network management
tool operates similarly to the SNMP SEND command; however, the SNMP request
that causes the message to be issued to the users also specifies the action to be
taken after the message is delivered. One possible action is a shutdown request.
Requesting a shutdown-after-message is similar to issuing a SEND command
followed by a RELOAD command. Because the ability to cause a reload from the
network is a powerful feature, it is protected by this configuration command. To
use this SNMP message reload feature, the device configuration must include the
SNMP-SERVER SYSTEM-SHUTDOWN global configuration command. The full
command syntax follows.
snmp-server system-shutdown
no snmp-server system-shutdown
The no snmp-server system-shutdown option prevents a SNMP system
shutdown request (from an SNMP manager) from resetting the DECbrouter 90
agent.

Configuring the Trivial File Transfer Protocol (TFTP) Server
You can configure the DECbrouter 90 to act as a limited trivial file transfer
protocol (TFTP) server from which other DECbrouter 90s can load their software.
As a TFTP server host, the DECbrouter 90 responds to TFTP read request
messages by sending a copy of its flash ROM software to the requesting host.
The TFTP read request message must use the file name that you specified in the
router configuration.
To specify TFTP server operation for a communication server, use the TFTPSERVER SYSTEM global configuration command. The full syntax follows.
tftp-server system filename ip-access-list
no tftp-server system filename ip-access-list
This command has two arguments: filename and list. The argument filename is
the name you give the communication server flash ROM file, and the argument
ip-access-list is an IP access-list number.
The system sends a copy of the Flash ROM software to any host that issues a
TFTP read request with this filename. To learn how to specify an access list, see
DECbrouter 90T Products, Configuration and Reference, Volume 2, Chapter 5,
"Routing IP."
You can specify multiple file names by repeating the TFTP-SERVER SYSTEM
command. To remove a previously defined file name, use the NO TFTP-SERVER
system command and append the appropriate file name and an access list
number.

4–32 Configuring the System

Configuring the System
Configuring the Trivial File Transfer Protocol (TFTP) Server

Example
This command causes the router to send, via TFTP, a copy of the flash ROM
software when it receives a TFTP read request for the file goodimage. The
requesting host is checked against access list 22.
tftp-server system goodimage 22

Tailoring Use of Network Services
The SERVICE global configuration command tailors the DECbrouter 90’s use
of network-based services. Some SERVICE commands also configure system
defaults; see decimal-tty for an example. The full command syntax follows.
service keyword
no service keyword
The argument keyword is one of the following:
•

config—Specifies TFTP autoloading of configuration files; disabled by default
on systems with nonvolatile memory.

•

decimal-tty—Specifies that line numbers be displayed and interpreted as
decimal numbers rather than octal numbers; disabled by default.

•

finger—Allows Finger protocol requests (defined in RFC 742) to be made of
the router; enabled by default. This service is equivalent to issuing a remote
SHOW USERS command.

•

tcp-keepalives-{in | out}—Generates keepalive packets on idle network
connections. The in keyword generates them on incoming connections
(initiated by remote host); the out keyword generates them on outgoing
connections (initiated by a user). There is a column in the EXEC show tcp
display showing the keepalive statistics. The wakeups row shows how many
keepalives have been transmitted without receiving any response (this is
reset to 0 when a response is received).

The NO SERVICE command disables the specified service or function.

Example
The following command enables TFTP autoloading of configuration files:
service config

Redirecting System Error Messages
By default, the DECbrouter 90 sends the output from the EXEC command debug
and system error messages to the console terminal.
To redirect these messages, as well as output from asynchronous events such
as interface transition, to other destinations, use the LOGGING configuration
command options.

Configuring the System 4–33

Configuring the System
Redirecting System Error Messages
These destinations include the console terminal, virtual terminals, and UNIX
hosts running a syslog server; the syslog format is compatible with 4.3 BSD
UNIX.
To configure message logging, you need to be in the configuration command
collection mode. To enter this mode, use the EXEC command CONFIGURE at the
EXEC prompt (see the section Entering Configuration Mode in Chapter 2 for the
procedure). The following sections describe how to implement these redirection
options.

Enabling Message Logging
To enable or disable message logging, use the following global configuration
commands:
logging on
no logging on
The LOGGING ON command enables message logging to all supported
destinations other than the console. This behavior is the default.
The NO LOGGING on command enables logging to the console terminal only.

Logging Messages to an Internal Buffer
The default logging device is the console; all messages are displayed on the
console unless otherwise specified.
To log messages to an internal buffer, use the logging buffered global
configuration command. The full command syntax follows.
logging buffered
no logging buffered
The LOGGING BUFFERED command copies logging messages to an internal
buffer instead of writing them to the console terminal. The buffer is circular in
nature, so newer messages overwrite older messages. To display the messages
that are logged in the buffer, use the EXEC command SHOW LOGGING. The
first message displayed is the oldest message in the buffer.
The NO LOGGING BUFFERED command cancels the use of the buffer and
writes messages to the console terminal; this is the default.

Logging Messages to the Console
To limit how many messages are logged to the console, use the LOGGING
CONSOLE global configuration command. The full syntax of this command
follows.
logging console level
no logging console
The LOGGING CONSOLE command limits the logging messages displayed on
the console terminal to messages with a level number at or below the specified
severity level, which is specified by the level argument.

4–34 Configuring the System

Configuring the System
Redirecting System Error Messages
The argument level can be one of the keywords listed in Table 4–3. They are
listed in order from the most severe to the least severe level.
Table 4–3 Logging Message Keywords and Levels
Level

Keyword

Description

Syslog Definition

emergencies

System is unusable

LOG_EMERG

alerts

Immediate action is needed

LOG_ALERT

critical

Critical conditions exist

LOG_CRIT

errors

Error conditions exist

LOG_ERR

warnings

Warning conditions exist

LOG_WARNING

notification

Normal, but significant,
conditions exist

LOG_NOTICE

informational

Informational messages

LOG_INFO

debugging

Debugging messages

LOG_DEBUG

The default is to log messages to the console at the warnings level.
The NO LOGGING CONSOLE command disables logging to the console terminal.

Example
This command sets console logging of messages at the debug level:
!
logging console debug
!

Logging Messages to Another Monitor
To limit the level of messages to log to the terminal lines (monitors), use the
LOGGING MONITOR command. The full syntax of this command follows.
logging monitor level
no logging monitor
The LOGGING MONITOR command limits the logging messages displayed on
terminal lines other than the console line to messages with a level at or above
level. The argument level is one of the keywords described for the LOGGING
CONSOLE command in the previous section, "Logging Messages to the Console."
To display logging messages on a terminal, use the privileged EXEC command
TERMINAL MONITOR.
The NO LOGGING MONITOR command disables logging to terminal lines other
than the console line.
This command sets the level of messages displayed on monitors other than the
console to notifications:
!
logging monitor notifications
!

Configuring the System 4–35

Configuring the System
Redirecting System Error Messages
Logging Messages to a UNIX Syslog Server
To log messages to the syslog server host, use the LOGGING global configuration
command. The full syntax is as follows:
logging internet-address
no logging internet-address
The LOGGING command identifies a syslog server host to receive logging
messages. The argument internet-address is the Internet address of the host.
By issuing this command more than once, you build a list of syslog servers that
receive logging messages. The NO LOGGING command deletes the syslog server
with the specified address from the list of syslogs.

Limiting Messages to a Syslog Server
To limit how many messages are sent to the syslog servers, use the LOGGING
TRAP global configuration command. Its full syntax follows.
logging trap level
no logging trap
The LOGGING TRAP command limits the logging messages sent to syslog
servers to messages with a level at or above level. The argument level is one of
the keywords described for the LOGGING CONSOLE command in Table 4-3.
To send logging messages to a syslog server, specify its host address with the
LOGGING command.
The default trap level is informational.
The NO LOGGING TRAP command disables logging to syslog servers.
The current software generates four categories of the syslog messages:
•

Error messages about software or hardware malfunctions, displayed at the
errors level.

•

Output from the DEBUG commands, displayed at the debugging level.

•

Interface up/down transitions and system restart messages, displayed at the
notifications level.

•

Reload requests and low-process stack messages, displayed at the
informational level.

The EXEC command SHOW LOGGING displays the addresses and levels
associated with the current logging setup. The command output also includes
ancillary statistics.

Example
To set up the syslog daemon on a 4.3 BSD UNIX system, include a line such as
the following in the file /etc/syslog.conf:
local7.debug /usr/adm/logs/tiplog
The local7 keyword specifies the logging facility to be used.
The debug argument specifies the syslog level. See the previous level arguments
list for other arguments that can be listed.

4–36 Configuring the System

Configuring the System
Redirecting System Error Messages
The UNIX system sends messages at or below this level to the file specified in
the next field. The file must already exist, and the syslog daemon must have
permission to write to it.

Configuring Console and Virtual Terminal Lines
To configure your console and virtual terminal lines you need to be in the
configuration command collection mode. To enter this mode, use the EXEC
command CONFIGURE at the EXEC prompt (see the section Entering
Configuration Mode in Chapter 2 for the procedure).

Starting Line Configuration
To start configuring a terminal line, use the LINE command. This command
identifies a specific line for configuration and starts line configuration command
collection.
The LINE command has the following syntax:
line [type-keyword] first-line [last-line]
This command can take up to three arguments: a keyword, a line number, or a
range of line numbers.
The optional argument type-keyword specifies the type of line to be configured; it
is one of the following keywords:
•

console—Console terminal line

•

vty—Virtual terminal for remote console access

When the line type is specified, the argument first-line is the relative number of
the terminal line (or the first line in a contiguous group) you want to configure.
Numbering begins with zero.
The optional argument last-line then is the relative number of the last line in a
contiguous group you want to configure.
If you omit type, then first-line and last-line are absolute rather than relative
line numbers. To display absolute line numbers, use the EXEC command SHOW
USERS ALL.
The router displays an error message if you do not specify a line number.
Note
Line numbers, by default, are octal on the routers.
The LINE command enables you to easily configure a large group of lines all
at once. After you set the defaults for the group, you can use additional LINE
commands and subcommands to set special characteristics, such as location, for
individual terminal lines.

Example
The following command starts configuration for the first five virtual terminal
lines:
line vty 0 4

Configuring the System 4–37

Configuring the System
Configuring Console and Virtual Terminal Lines
Establishing Line Passwords
When you start an EXEC on a line with password protection, the EXEC prompts
for the password. If you enter the correct password, the EXEC prints its normal
prompt. You can try to enter a password three times before the EXEC exits and
returns the terminal to the idle state.
To specify a password, use the PASSWORD line subcommand. Its full syntax
follows.
password text
no password
The text argument can contain any alphanumeric characters, including spaces, up
to 80 characters. The password checking is case-sensitive. The password Secret
is different from the password secret, for example, and the password two words is
an acceptable password.

Example
This command sets the words "Big Easy" as the password on line 1:
!
line 1
password Big Easy
!

Setting Widths for International Character Sets for the Interface
These commands allow you to use graphical and international characters in
banners and prompts, and to add special characters such as software flow control.
Use these commands to set the character widths for a specific line to values
other than the default values defined by the global commands described in the
earlier section, Configuring the Global System Parameters. The decision to use
the global configuration commands or line configuration subcommands depends
on the types and numbers of terminals connected to the router, as follows:
•

If a large number of connected terminals support nondefault ASCII bit
settings, use the global configuration commands. (See the section Configuring
the Global System Parameters earlier in the chapter for default settings.)

•

If only a few of the connected terminals support nondefault ASCII bit settings,
use the following line configuration subcommands or the EXEC terminal
exec-character-bits, terminal data-character-bits, or TERMINAL
SPECIAL-CHARACTER-BITS commands described in Chapter 3 to selectively
configure the lines.

Use the following line subcommands to configure character widths on a per-line
basis.
exec-character-bits {8 | 7}
special-character-bits {8 | 7}
The EXEC-CHARACTER-BITS command configures the character widths of
EXEC and configuration command characters. The default value is 7 bits, which
results in the use of a 7-bit ASCII character set. Configuring the EXEC character
width to 8 allows you to add special graphical and international characters in
4–38 Configuring the System

Configuring the System
Configuring Console and Virtual Terminal Lines
banners and prompts. Setting this value to 8 allows additional international and
graphical characters in banner messages and prompts.
The SPECIAL-CHARACTER-BITS command configures the number of characters
used in special characters such as software flow control and escape characters.
The default special-character width is 7. Configuring the width to 8 bits allows
you to use twice as many special characters as with the 7-bit setting.
Note
Setting the EXEC character width to 8 bits can cause failures. If a user
on a terminal that is sending parity enters the command HELP, an
"unrecognized command" message appears because the system is reading
all 8 bits, although the eighth bit is not needed for the HELP command.
See the section Setting Default Widths for International Character Sets earlier in
the chapter for global character-width commands.

Example
This example allows full 8-bit international character sets by default, except for
the console, which is a dumb ASCII terminal. It illustrates use of the global
configuration command and the line configuration subcommands.
default-value exec-character-bits 8
!
line 0
exec-character-bits 7

Establishing Connection Restrictions
To establish connection restrictions on the lines to some Internet addresses, use
the ACCESS-CLASS line subcommand. The full command syntax follows.
access-class list {in | out}
no access-class list {in | out}
The ACCESS-CLASS subcommand restricts connections on a line or group of lines
to certain Internet addresses. The argument list is an integer from 1 through 99
that identifies a specific access list of Internet addresses. The keyword in applies
to incoming connections, such as virtual terminals. The keyword out applies to
outgoing Telnet connections. The NO ACCESS-CLASS command removes access
restrictions on the line for the specified connections.

Example
This example subcommand sets restrictions on access list 1 for outgoing Telnet
connections:
access-class 1 out
See the DECbrouter 90T Products, Configuration and Reference, Volume 2,
Chapter 5, "IP Routing" for information about configuring access lists.

Configuring the System 4–39

Configuring the System
Configuring Console and Virtual Terminal Lines
Suppressing Banner Messages
By default, messages defined by the BANNER MOTD and BANNER EXEC
commands are always displayed. This condition is defined by the EXEC-BANNER
line subcommand. Its full syntax follows.
exec-banner
no exec-banner
To suppress display of a banner, enter the NO EXEC-BANNER command.

Example
These commands suppress the banner on virtual terminal lines 0 through 4:
line vty 0 4
no exec-banner

Turning On and Off the Vacant Banner
The router will display a message on the console when there is no active EXEC.
This message, called the vacant message, is different from the banner message
displayed when an EXEC process is activated.
To turn the vacant message banner on or off, use the VACANT-MESSAGE line
configuration subcommands. The VACANT-MESSAGE command enables the
banner to be displayed on the screen of an idle terminal. The full syntax of this
command follows.
vacant-message [c message c]
no vacant-message

The VACANT-MESSAGE subcommand without any arguments causes the default
message to be displayed. If you desire a banner, follow vacant-message with
one or more blank spaces and a delimiting character (c) that you choose. Then
type one or more lines of text (message), terminating the text with the second
occurrence of the delimiting character.
The NO VACANT-MESSAGE line configuration subcommand suppresses a banner
message.

Example
This example will turn on the system banner and display a message:
line 0
vacant-message #
Welcome to Digital Equipment Corp.
This is the console terminal of the router Dross.
#

Note
You cannot use the delimiting character in the banner message.

4–40 Configuring the System

Configuring the System
Configuring Console and Virtual Terminal Lines

Setting the Escape Character
The ESCAPE-CHARACTER line subcommand defines the escape character. The
full syntax of this command is as follows:
escape-character decimal-number
no escape-character
The argument decimal-number is the ASCII decimal representation of the desired
escape character or an escape character (Ctrl/P, for example). Typing the escape
character followed by the X key returns you to the EXEC when you are connected
to another computer. The default escape character is Ctrl/^. (See DECbrouter 90
Products, Configuration and Reference, Volume 3, Appendix E, "ASCII Character
Set," for a list of ASCII characters.)
The operating software interprets break on the console as an attempt to halt the
system.
Note
Depending upon the configuration register setting, console breaks either
will be ignored or will cause the server to shut down. The Break key
cannot be used as the escape character on the router.
The NO ESCAPE-CHARACTER line configuration subcommand reinstates the
default escape character.

Example
This command changes the escape characters to Ctrl/P (ASCII character 17):
!
line 5
escape-character 17
!

Setting the Terminal Location
To set the location of the terminal, use the LOCATION line subcommand. The
full syntax of this command follows.
location text
no location
This subcommand is for informational purposes only; it is not used by any
aspects of the system software. The argument text is the desired description. The
description appears in the output of the EXEC command SYSTAT. A maximum of
80 characters can be entered.
The NO LOCATION subcommand removes the information.

Configuring the System 4–41

Configuring the System
Configuring Console and Virtual Terminal Lines
Example
This command describes the location of the terminal on line 2 as being Andrea’s
terminal:
!
line 2
location Andrea’s terminal
!

Setting the EXEC Timeout Intervals
The EXEC command interpreter waits for a specified interval of time until
the user starts input. If no input is detected, the EXEC resumes the current
connection. If no connections exist, the EXEC returns the terminal to the idle
state and disconnects the incoming session.
To set this interval, use the EXEC-TIMEOUT line configuration subcommand.
The full syntax of the command follows.
exec-timeout minutes [seconds]
no exec-timeout
The argument minutes is the number of minutes, and the optional argument
seconds specifies additional interval time in seconds. The default interval is ten
minutes; an interval of zero specifies no timeouts.
The NO EXEC-TIMEOUT subcommand removes the timeout definition. It is the
same as entering EXEC-TIMEOUT 0.

Examples
This command sets an interval of 2 minutes, 30 seconds:
exec-timeout 2 30
This command sets an interval of 10 seconds:
exec-timeout 0 10

Setting the Screen Length
To set the terminal screen length, use the LENGTH line configuration
subcommand. The full syntax of the command follows.
length screen-length
no length
The argument screen-length is the number of lines on the screen. The router uses
this value to determine when to pause during multiple-screen output. The default
length is 24 lines. A value of zero disables pausing between screens of output.
The NO LENGTH command is the same as entering the command LENGTH 0.
Note
Not all commands pay attention to the configured screen length. For
example, the SHOW TERMINAL command assumes a screen length of 24
lines or more.

4–42 Configuring the System

Configuring the System
Configuring Console and Virtual Terminal Lines

Setting Notification
To enable the terminal to notify the user about pending output, use the NOTIFY
line subcommand. The full syntax of the command follows.
notify
no notify
The NOTIFY subcommand sets a line to inform a user who has multiple,
concurrent Telnet connections when output is pending on a connection other than
the current connection.
The NO NOTIFY line configuration subcommand ends notification and is the
default.

Setting Character Padding
To set the padding on characters, use the PADDING line configuration
subcommand. The full syntax of the command follows.
padding decimal-number count
no padding decimal-number
The PADDING subcommand sets padding for a specified output character. The
argument decimal-number is the ASCII decimal representation of the character,
and the argument count is the number of NUL bytes sent after that character.
The NO PADDING line configuration subcommand removes padding for the
specified output character.
The following command pads Return (ASCII character 13) with 25 NUL bytes:
padding 13 25

Global System Configuration Command Summary
This section lists all of the global system configuration commands in alphabetical
order.
[no] banner {motd | exec | incoming} c text c
Displays the message that the EXEC command interpreter displays whenever
a user starts any EXEC process or activates a line. The motd, exec, and
incoming keywords control when the banner message is displayed. The
argument c specifies a delimiting character of your choice. The argument text
specifies the message to be shown on the screen whenever an interface line is
activated.
[no] boot buffersize bytes
Specifies the size of the buffer to be used for netbooting a host or a network
configuration file. The argument bytes by default is the size of your
nonvolatile memory (32 kilobytes). There is no minimum or maximum
size that can be specified.

Configuring the System 4–43

Configuring the System
Global System Configuration Command Summary
[no] boot host filename [address]
Specifies the host configuration file name. The argument filename is the new
name for the host configuration file. If you omit the argument address, the
DECbrouter 90 uses the default broadcast address of 255.255.255.255. The
optional argument address allows you to specify a specific network host or a
subnet broadcast address.
[no] boot network filename [address]
Specifies the network configuration file name. The argument filename is
the new name for the network configuration file. If you omit the optional
argument address, the DECbrouter 90 uses the default broadcast address
of 255.255.255.255. The optional argument address allows you to specify a
specific network host or a subnet broadcast address.
[no] buffers {small | middle | big | large | huge} {permanent | max-free |
min-free | initial} number
Allows a network administrator to adjust initial buffer pool settings and
set limits at which temporary buffers are created and destroyed. The first
keyword denotes the size of buffers in the pool; the default number of the
buffers in a pool is determined by the hardware configuration. The second
keyword specifies the buffer management parameter to be changed, as
follows:
•

permanent—The number of permanent buffers that the system tries to
allocate.

•

max-free—The maximum number of free or unallocated buffers in a
buffer pool.

•

min-free—The minimum number of free or unallocated buffers in a
buffer pool.

•

initial—The number of additional temporary buffers that should be
allocated when the system is reloaded.

The argument number specifies the number of buffers to be allocated.
The NO BUFFERS command with appropriate keywords and arguments
restores the default buffer values.
[no] buffers huge size number
Dynamically resizes all huge buffers to the value that you supply. The buffer
size cannot be lowered below the default. The argument number specifies the
number of buffers to be allocated. The no version of the command with the
keyword and argument restores the default buffer values.

4–44 Configuring the System

Configuring the System
Global System Configuration Command Summary
copy flash tftp
Copies a flash TFTP image back to a TFTP server.
copy tftp flash
Copies a TFTP image into the current flash configuration.
copy mop flash
Copies a MOP image into the current flash configuration.
default-value exec-character-bits {8 | 7}
Configures the character widths of EXEC and configuration command
characters. The default value is 7 bits, which results in the use of a 7-bit
ASCII character set. Configuring the EXEC character width to 8 bits allows
you to add special graphical and international characters in banners and
prompts.
default-value special-character-bits {8 | 7}
Configures the number of characters used in special characters such as
software flow control, hold, escape, and disconnect characters. The default
special-character width is 7. Configuring the width to 8 allows you to use
twice as many special characters as with the 7-bit setting.
enable
Allows you to enter the privileged command level.
enable password password
Assigns a password for the privileged command level. The argument
password is case-sensitive and specifies the password prompted for in
response to the EXEC command ENABLE.
[no] enable last-resort {succeed | password}
Allows you to specify what happens if the TACACS servers used by the
ENABLE command do not respond. The default action is to fail. The
keywords change this default action:
•

succeed—Allows you to enable without further question.

Configuring the System 4–45

Configuring the System
Global System Configuration Command Summary
•

password—Allows you to enable by entering the privileged command
level.

The no version of the command restores the default.
[no] enable use-tacacs
Enables or disables use of TACACS to check the user ID and password
supplied to the EXEC ENABLE command.
hostname name
Specifies the name for the router. The default is Router.
[no] logging internet-address
Identifies a syslog server host to receive logging messages. The argument
internet-address is the Internet address of the host.The NO LOGGING
command deletes the syslog server with the specified address from the list of
syslogs.
[no] logging buffered
Copies logging messages to an internal buffer instead of writing them to the
console. The no version of the command cancels this behavior and writes
messages to the console terminal; this is the default.
[no] logging console level
Limits the logging of messages displayed on the console terminal to messages
with a level at or above the specified severity, which is specified by the level
argument. The argument level can be one of the following keywords, listed
here in order from the most severe to the least severe level.
•

emergencies—System unusable

•

alerts—Immediate action needed

•

critical—Critical conditions

•

errors—Error conditions

•

warnings—Warning conditions (default)

•

notification—Normal but significant conditions

•

informational—Informational messages only

•

debugging—Debugging messages

The NO LOGGING CONSOLE command disables logging to the console
terminal.

4–46 Configuring the System

Configuring the System
Global System Configuration Command Summary

[no] logging monitor level
Limits the logging messages displayed on terminal lines other than the
console line to messages with a level at or above level. The argument level is
one of the keywords described for the LOGGING CONSOLE command. The
NO LOGGING MONITOR command disables logging to terminal lines other
than the console line.
[no] logging on
Enables or disables message logging to all supported destinations except the
console. Enabled message logging is the default.
[no] logging trap level
Limits the logging messages sent to syslog servers to messages with a level
at or above level. The argument level is one of the keywords described for the
LOGGING CONSOLE command.
[no] service keyword
Tailors the router’s use of network-based services. The argument keyword is
one of the following:
•

config—Specifies TFTP autoloading of configuration files; disabled by
default on system with nonvolatile memory.

•

decimal-tty—Specifies that line numbers be displayed and interpreted as
decimal numbers rather than octal numbers; disabled by default.

•

finger—Allows finger protocol requests (defined in RFC 742) to be made
of the router; enabled by default.

•

password-encryption—Displays passwords in encrypted form when a
SHOW CONFIG command is issued.

•

tcp-keepalives-{in | out}—Generates keepalive packets on idle network
connections. The in keyword generates them on incoming connections;
the out keyword generates them on outgoing connections.

The NO SERVICE command disables the specified service or function.
no snmp-server
Disables the SNMP operations.

Configuring the System 4–47

Configuring the System
Global System Configuration Command Summary
[no] snmp-server access-list list
Sets up an access list that determines which hosts can send requests to the
DECbrouter 90. The argument list is an integer from 1 through 99 that
specifies an IP access list.
[no] snmp-server community string [RO | RW] [list]
Enables or disables SNMP server operation on the DECbrouter 90. The
argument string specifies a community string that acts like a password and
permits access to the SNMP protocol.
[no] snmp-server host address community-string [snmp | tty]
Specifies which host or hosts should receive TRAP messages. Issue the
SNMP-SERVER HOST command once for each host acting as a TRAP
recipient. The argument address is the name or Internet address of the host.
The argument community-string is the password-like community string set
with the SNMP-SERVER COMMUNITY command. These optional keywords
direct the TRAP:
•

snmp—Causes all SNMP-type TRAP messages to be sent and starts the
DECbrouter 90-specific RELOAD TRAP message.

•

tty—Causes TCP connection TRAP messages to be included.

[no] snmp-server packetsize bytes
Sets or removes control over the largest SNMP packet size permitted when
the SNMP server is receiving a request or generating a reply. The argument
bytes is a byte count from 484 through 8192. The default is 484.
[no] snmp-server queue-length length
Defines the length of the message queue for each TRAP host. The argument
length is the number of TRAP events that can be held before the queue must
be emptied; the default is ten. The no version of the command resets the
queue length to the default.
[no] snmp-server system-shutdown
Allows or restricts use of the SNMP message reload feature and prevents an
SNMP system shutdown request from resetting the DECbrouter 90 agent.
[no] snmp-server trap-authentication
Allows or restricts the DECbrouter 90 from sending a TRAP message when it
receives a packet with an incorrect community string.

4–48 Configuring the System

Configuring the System
Global System Configuration Command Summary
[no] snmp-server trap-timeout seconds
Defines how often to try resending TRAP messages on the retransmission
queue. The argument seconds sets the interval for resending the messages.
The default is set to 30 seconds. The no form of the command restores the
default.
[no] tacacs-server attempts count
Controls the number of login attempts that can be made on a line set up for
TACACS verification. The argument count is the number of attempts. The
default is three attempts.
[no] tacacs-server authenticate {connect | enable}
Specifies that a response is required from the network or communication
server to indicate whether the user can perform the indicated action. Actions
that require a response include the following:
•

connect—User makes TCP connections.

•

enable—User enters the ENABLE command.

The no form of the command disables the action.
[no] tacacs-server extended
Enables or disables an extended TACACS mode. This mode provides
information about the terminal requests for use in setting up UNIX auditing
trails and accounting files for tracking use of terminal servers and routers.
[no] tacacs-server host name
Specifies a TACACS host. The argument name is the name or Internet
address of the host. You can use multiple commands to specify multiple hosts.
[no] tacacs-server last-resort {password | succeed}
Causes the DECbrouter 90 to request the privileged password as verification,
or forces successful login without further input from the user, depending upon
the keyword specified.
•

password—Allows the user to access the privileged-level command mode
by entering the password set by the ENABLE command.

•

succeed—Allows the user to access the privileged-level command mode
without further question.

The no form of the command disables the action.

Configuring the System 4–49

Configuring the System
Global System Configuration Command Summary
[no] tacacs-server notify {connect | enable | logout}
Causes a message to be transmitted to the TACACS server, with
retransmission being performed by a background process for up to five
minutes. The keywords specify notification of the TACACS server whenever a
user does one of the following:
•

connect—Makes TCP connections.

•

enable—Enters the ENABLE command.

•

logout—Logs out.

The no form of the command disables the messages.
tacacs-server optional-passwords
Specifies that the first TACACS request to a TACACS server is made without
password verification. Supports all TACACS requests—login, SLIP and
enable.
[no] tacacs-server retransmit retries
Specifies the number of times the server will search the list of TACACS server
hosts before giving up. The argument retries is the retransmit count. The
default is two retries. The no form of the command restores the default.
[no] tacacs-server timeout seconds
Sets the interval the server waits for a server host to reply. The argument
seconds specifies the number of seconds. The default interval is five seconds.
The no form of the command restores the default.
[no] tftp-server system filename ip-access-list
Specifies or removes TFTP server operation for the DECbrouter 90. The
argument filename is the name given to the router flash ROM file, and the
argument access-list is an IP access list number.
username name[ nopassword | password encryptiontype password]
username name [accesslist number]
username name [autocommand command]
username name [noescape] [nohangup]
Creates special-case user name-based authentications. Multiple USERNAME
commands can be used to specify options for a single user.
The nopassword keyword means that no password is required for this user
to log in. This is usually most useful in combination with the autocommand
keyword.

4–50 Configuring the System

Configuring the System
Global System Configuration Command Summary
The password keyword specifies a possibly encrypted password for this user
name.
The encryptiontype argument is a single-digit number. Currently defined
encryption types are 0, which means no encryption, and 7, which specifies
a Digital-defined encryption algorithm. Passwords entered unencrypted are
written out with the Digital encryption. Passwords can contain embedded
spaces and must be the last option specified in the USERNAME command.
The accesslist keyword specifies an outgoing access list that overrides the
access list specified in the ACCESS CLASS line configuration subcommand.
It is used for the duration of the user’s session. The access list number is
specified by the number argument.
The autocommand keyword causes the command specified by the command
argument to be issued automatically after the user logs in. When the
command is complete, the session is terminated. As the command can be any
length and contain embedded spaces, commands using the autocommand
keyword must be the last option on the line.
The noescape keyword prevents a user from using an escape character on
the host to which he is connected.
The nohangup keyword prevents the DECbrouter 90 from disconnecting the
user after an automatic command (set up with the autocommand keyword)
has completed. Another login prompt is provided to the user.

Line Configuration Subcommand Summary
This section contains a summary of all the line configuration subcommands in
alphabetical order.
[no] access-class list {in | out}
Restricts or permits connections on a line or group of lines to certain Internet
addresses. The argument list is an integer from 1 through 99 that identifies a
specific access list of Internet addresses. The keyword in applies to incoming
connections; the keyword out applies to outgoing Telnet connections.
[no] escape-character decimal-number
Sets or removes the escape character on the specified line. The argument
decimal-number is either the ASCII decimal representation of the character
or a control sequence (Ctrl/E, for example). The default escape character is
Ctrl/^.
[no] exec-banner
Enables or disables a banner. By default, a banner is displayed on the
console. To suppress display of a banner, enter the no variation of the
command.

Configuring the System 4–51

Configuring the System
Line Configuration Subcommand Summary
exec-character-bits {8 | 7}
Configures the character widths of EXEC and configuration command
characters. The default value is 7 bits, which results in the use of a 7-bit
ASCII character set. Configuring the EXEC character width to 8 allows you
to add special graphical and international characters in banners and prompts.
[no] exec-timeout minutes [seconds]
Sets the interval the EXEC waits for user input before resuming the current
connection, or if no connections exist, before returning the terminal to the idle
state and disconnecting the incoming session. The argument minutes is the
number of minutes, and the optional argument seconds specifies additional
interval time in seconds. The default interval is ten minutes; an interval of
zero specifies no timeouts. The no form of the command restores the default.
[no] length screen-length
Sets the terminal screen length. The argument screen-length is the number of
lines on the screen. The DECbrouter 90 uses this value to determine when to
pause during multiple-screen output. The default length is 24 lines. A value
of 0 (zero) or the no form of the command disables pausing between screens
of output.
line [type-keyword] first-line [last-line]
Identifies a specific line for configuration and starts line configuration
command collection. The optional argument type-keyword specifies the type of
line to be configured; it can be console, aux, or vty. When the line type is
specified, the argument first-line is the relative number of the terminal line
(or the first line in a contiguous group) you want to configure. The optional
argument last-line is the relative number of the last line in a contiguous
group you want to configure. If you omit type, then first-line and last-line are
absolute rather than relative line numbers.
line aux port-address
This variation of the LINE command configures the auxiliary port. When
configuring the auxiliary port, address it as line 0.
[no] location text
Enters or removes information-only data about the terminal location and/or
status. The argument text is the desired description.

4–52 Configuring the System

Configuring the System
Line Configuration Subcommand Summary
[no] login
Enables or disables password-checking for the password specified by the
PASSWORD command.
[no] login tacacs
Causes the TACACS user ID and password checking mechanism to be used
instead of the regular password checking. The no form of the command
disables this mechanism.
[no] notify
Enables or disables line notification of a user who has multiple, concurrent
Telnet connections when output is pending on a connection other than the
current line.
[no] padding decimal-number count
Sets or unsets padding for a specified output character. The argument
decimal-number is the ASCII decimal representation of the character; and the
argument count is the number of NUL bytes sent after that character.
[no] password text
Specifies a password. The text argument specifies a password. It can contain
any alphanumeric characters, including spaces, up to 80 characters. The no
version of the command removes the specified password.
[no] service password-encryption
Controls whether privileged command and line passwords are encrypted. The
no version of the command turns off password encryption.
special-character-bits {8 | 7}
Configures the number of characters used in special characters such as
software flow control and escape characters. The default special-character
width is 7. Configuring the width to 8 bits allows you to use twice as many
special characters as with the 7-bit setting.
[no] vacant-message [c message c]
Controls whether or not a banner is displayed on the screen of an idle
terminal. The command without any arguments causes the default message
to be displayed. The NO VACANT-MESSAGE command suppresses a banner
message. To display a banner, follow vacant-message with one or more
blank spaces and a delimiting character (c) that you choose, then type one

Configuring the System 4–53

Configuring the System
Line Configuration Subcommand Summary
or more lines of text (message), and terminate the text with the second
occurrence of the delimiting character.

4–54 Configuring the System

5
Using MOP
This chapter provides information about how to use Digital Equipment
Corporation’s Maintenance Operation Protocol (MOP). It includes the following
topics:
•

Overview of MOP and configuring MOP on your router

•

Using MOP to copy an image into Flash memory and to boot from a MOP
boot server

•

Network configurator support and remote system management

•

Debugging MOP

There is a command summary at the end of the chapter.
Note
The device referred to as a "MOP boot server" in this chapter can be
any device running a Digital operating system that supports MOP.
This includes a range of devices, from a VMS timesharing system to an
Infoserver 150.

MOP Overview
Digital Equipment Corporation’s MOP is supported on Ethernet and serial
interfaces. The DECbrouter 90 supports the following MOP features:
•

Periodic ID messages (MOP SYSID) The router periodically broadcasts "hello"
messages that are used by network management tools to produce network
maps.

•

System software loading Loads system software from a MOP boot server over
the network.

•

Flash memory loading Copies system software updates to Flash memory over
the network.

•

Remote router management Establishes a connection from a MOP boot server
to a virtual port on the router to re- configure or examine the state of the
router.

MOP was designed to be used for basic management of network components. It is
a special-purpose protocol that does not support many of the features supported
by other protocols.

Using MOP 5–1

Using MOP
MOP Overview
MOP can only be used between systems connected to the same local area network
or between systems connected by transparent bridging. It cannot be routed,
because it does not have a network layer. MOP does not store connection context
information, so only one MOP function can be active on an interface. For
example, only one MOP virtual terminal session can be supported at one time.
MOP references a system by its MAC address, which can be displayed by using
the SHOW INTERFACE command. When referring to a remote system, you may
have to specify both an interface and a MAC address.
Note
If you bridge MOP and use filters, note that all MOP file-loading
operations use the protocol type 6001 and the multicast address
AB00.0001.0000. All other MOP opera- tions use the protocol type
6002 and the multicast address AB00.0002.0000.

Configuring MOP
This section describes how to configure MOP using global and interface
configuration commands.

Enabling MOP for an Interface
To enable MOP on an interface, use the following interface configuration
subcommand:
mop enabled
no mop enabled
This command enables all MOP operations on an interface. MOP is enabled by
default on Ethernet interfaces and disabled on all other interfaces. Use the NO
MOP ENABLED command to disable MOP.

Example
The following example enables MOP on interface serial 0:
interface serial 0
mop enabled

Sending MOP System ID Messages
If MOP is enabled on an interface, it will transmit a system ID message every 8
to 12 minutes by default. This message is used by various network management
tools. Use the following interface subcommand to configure your router to send
system ID messages:
mop sysid
no mop sysid

5–2 Using MOP

Using MOP
Sending MOP System ID Messages
If you do not use the network management tools and are concerned about
network traffic levels (for example, over slow serial lines), use the NO MOP
SYSID command to disable system ID messages. With system ID messages
disabled, you can use MOP but the router will not generate system ID messages.

Example
The following configuration disables MOP system ID messages on interface serial
0:
interface serial 0
mop enabled
no mop sysid

Network Configurator Support
MOP includes network management software called the network configurator.
MOP maintains protocol messages that the network configurator uses to generate
a network map, which is a list of the stations operating on a LAN. Every 8 to 12
minutes, a system that supports MOP sends out a system ID message informing
management stations of its existence.
Within the system ID message, there is a communications device code that
informs the management station of the type of device on the network. The
DECbrouter 90T uses a MOP communications device code of 121 (decimal). (This
differs from other Digital products.)

Setting Retransmit Timer Interval
By default, when the router transmits a request that requires a response from
a MOP boot server and the server does not receive a response, the message
will be retransmitted after four seconds. If the MOP boot server and router are
separated by a slow serial link, it may take longer than four seconds for the
router to receive a response to its message. Therefore, you may want to configure
the router to wait longer than four seconds before retransmitting the message if
you are using such a line.
Use the following command to change the length of time the router waits before
retransmitting a message:
mop retransmit-timer seconds
no mop retransmit-timer seconds
The argument seconds is a number from 1 through 20. The default value is 4.

Example
In the following example, if the MOP boot server does not respond within 10
seconds after the router sends a message, the server will retransmit the message.
interface serial 0
mop enabled
mop retransmit-timer 10

Using MOP 5–3

Using MOP
Setting the Maximum Number of Retransmissions

Setting the Maximum Number of Retransmissions
By default, the router will retransmit a request up to eight times before declaring
a failure. If you have noisy or congested lines with very high drop rates, you may
want to configure the router to retransmit messages more than eight times.
Use the following command to alter the number of times a router will retransmit
a message:

mop retries count
no mop retries count
The argument count must be a number from 3 through 24. The default value is
8.

Example
In the following example, the router will attempt to retransmit a message to an
unresponsive host 11 times before declaring a failure.
interface serial 0
mop enabled
mop retries 11

Copying a MOP Image to Flash Memory
Your DECbrouter 90T comes from the factory pre-loaded with the latest router
software. However, when you receive updates, you will need to load the software
into the Flash memory of your router. Use the following command to use MOP to
copy a system image into Flash memory (note that MOP must be enabled on the
relevant interfaces):
copy mop flash
When you enter the COPY MOP FLASH command, the system prompts you for
the filename of the software image. You are then asked for a confirmation. You
can terminate the command at this point by entering n. If you confirm, and the
Flash memory has enough available space, you have the option of erasing any
existing files before writing into Flash memory. If no free space is available, or
if files have never been written to Flash memory, you must erase Flash memory
before copying the MOP image.
You do not need to specify the address of a MOP server; the system automatically
solicits a MOP boot server for the specified file by sending a multicast file request
message.

5–4 Using MOP

Using MOP
Copying a MOP Image to Flash Memory
Note
The router must be in bootstrap mode before you may execute the COPY
MOP FLASH command. In bootstrap mode, the router runs out of
conventional ROM, permitting the Flash to be erased. The router is in
bootstrap mode when the EXEC prompt ends in (boot)> (for example,
Router(boot)>). For instructions on placing the router in bootstrap
mode, please see page 4-10 in the DECbrouter 90 Configuration and
Reference, Volume 1 or the DECbrouter 90 Getting Started guide, the
section Setting the Configuration Register.

Examples
The following example shows the sample output of the prompts you will see when
you enter the COPY MOP FLASH command. In this example, the system image
xx-k is being copied to Flash memory, another file of the same name is already in
Flash and there is enough memory to copy it without erasing any existing files.
George(boot)# copy mop flash
Flash file directory:
File name/status
0 xx-k
[2264000/4194304 bytes free/total]
Name of file to copy ? xx-k
File xx-k already exists; it will be invalidated!
Copy xx-k from MOP server into flash memory ? [confirm]
2263936 bytes available for writing without erasure.
This line appears only if the same file already exists in Flash memory
In the following example, the Flash memory has no space available for the MOP
file.
George(boot)# copy mop flash
Flash is filled to capacity.
Erasure is needed before flash may be written.
Erase flash before writing? [confirm]
If Flash is filled to capacity, the command will terminate. If you enter a y, the
erase process will start. If Flash is not filled to capacity, and you enter n after
the "Erase flash before writing?" prompt, the copy process will continue.
Note
Make sure you have enough Flash memory space before entering n at
the "Erase flash before writing?" prompt. The Flash directory information
displayed after you enter the COPY MOP FLASH command and before
the prompts indicates the amount of free and total space in Flash memory.

Using MOP 5–5

Using MOP
Erasing Flash Memory

Erasing Flash Memory
When you enter commands to erase Flash memory, the system erases every bank
of Flash memory. For each bank of Flash memory, an e is displayed at periodic
intervals to indicate that the erase process is in progress. The entire erase
process takes several tens of seconds, depending on the total amount of Flash
memory.
The filename can be in either lowercase or uppercase. If the same file is copied
twice to Flash without an intermediate erase, and there is enough available Flash
memory to hold the two files, the first file will be invalidated and the second file
will become the valid file.

Example
The following example shows sample commands and output for copying a system
image named XX-K into a Flash memory that already contains a file named
XX-K. In this example, Flash memory is erased before copying the file XX-K into
Flash memory.
George(boot)# copy mop flash
Flash file directory:
File name/status
0 xx-k
[2264000/4194304 bytes free/total]
Name of file to copy ? XX-K
File XX-K already exists; it will be invalidated!
Copy XX-K from MOP server into flash memory ? [confirm]
2263936 bytes available for writing without erasure.
Erase flash before writing? [confirm]
Flash erase: erasing bank 0 .. eeeeeeeeeeeeeee
Mop2flash: Loading XX-K into flash from aa00.0400.9005 on Ethernet0 :
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!
Verify
checksum...vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvv
Verification successful:Length = 1930240, checksum = 0x3461

5–6 Using MOP

Using MOP
Erasing Flash Memory
The following example shows sample commands and output for copying a system
image named xx-k into Flash memory that already contains an image named
XX-K. In this example, Flash memory is not erased before loading the file:
George(boot)# copy mop flash
Flash file directory:
File name/status
0 XX-K
Name of file to copy ? xx-k
File xx-k already exists; it will be invalidated!
Copy xx-k from MOP server into flash memory ? [confirm]
2263936 bytes available for writing without erasure.
Erase flash before writing? [confirm]n
Mop2flash: Loading xx-k into flash from aa00.0400.9005 on Ethernet0 :
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!
Verify
checksum...vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvv
Verification successful:Length = 1930240, checksum = 0x3461
Note that the MOP boot server address (aa00.0400.9005) was obtained
automatically. The series of ! marks indicates that the copying process is active
over the network. The series of v marks indicate that a checksum verification of
the file written to Flash memory is taking place.
The following example shows sample commands and output for copying a system
image named xx-kf into Flash memory that already contains two images.
George(boot)# copy mop flash
Flash file directory:
File name/status
0 XX-K [deleted]
1 xx-k
[333696/4194304 bytes free/total]
Name of file to copy ? xx-kf
Copy xx-kf from MOP server into flash memory ? [confirm]
333632 bytes available for writing without erasure.
Erase flash before writing? [confirm]n
Mop2flash: Loading xx-kf into flash from aa00.0400.9005 on Ethernet0 :
!!!!!!!!!!!!!!Flash: final address 0x3400240 beyond flash range of
0x3400000.
Error programming flash memory.

Using MOP 5–7

Using MOP
Erasing Flash Memory
The following example shows sample commands and output for copying a system
image named xx-kf into the Flash memory that is already filled to capacity. In
this example the image is not copied into Flash memory.
George(boot)# copy mop flash
Flash file directory:
File name/status
0 XX-K [deleted]
1 xx-k
2 xx-kf [deleted]
[0/4194304 bytes free/total]
Name of file to copy ? xx-kf
Copy xx-kf from MOP server into flash memory ? [confirm]
Flash is filled to capacity.
Erasure is needed before flash may be written.
Erase flash before writing? [confirm]n
George#

Aborting the Copy Process
To abort the copy process, press the Ctrl, Shift, and 6 keys simultaneously. The
process will stop, but the partial file that was copied before the abort command
was issued will remain in Flash memory until it is erased.
When an image has been successfully copied into Flash, the commands SHOW
FLASH and SHOW FLASH ALL will provide a list of files present in Flash
memory.
For information about booting from Flash memory, see the section Automatically
Booting from Flash Memory in Chapter 4.

Remote Router Management
Using MOP on your device, you can create a virtual terminal connection to a
router. This allows you to execute all router commands as if your device were
connected to the router console.
To support remote management, set a password on the incoming virtual
terminal (VTY) lines or enable TACACS on the line. For more information, see
Establishing Passwords and System Security in Chapter 4.
To initiate a MOP session, you must the use services of the operating system
running on your boot server. For the VMS operating system, use the CONNECT
NODE or CONNECT VIA commands under the NCP program. Consult your
operating system documentation for more information.
Note
MOP is not designed to be used as a general-purpose, remote terminal
protocol. It places considerable load on both the host and router and
should only be used for remote system management.

5–8 Using MOP

Using MOP
Remote Router Management
Example
The following example shows a connection being established from a VMS system
to a router.
$ RUN SYS$SYSTEM:NCP
NCP> CONN VIA SVA-0 PHYSICAL ADDRESS 00-00-0C-04-05-06
Console connected (press CTRL/D when finished)
User Access Verification
Password:
chaos> show hardware
DECbrouter 90 Software (XX-K), Version 9.14(1)
Copyright (c) 1986-1992 by cisco Systems, Inc.
Compiled Fri 06-Apr-93 17:09
System Bootstrap, Version 4.6(1), SOFTWARE
pisa uptime is 1 day, 16 hours, 57 minutes
System restarted by reload
System image file is "dit/xx-k.91s", booted via flash
DECbrouter 90 (68030) processor (revision 0xA0) with 1024K/1024K bytes
of memory.
Processor board serial number 00000076
DDN X.25 software.
Bridging software.
1 Ethernet/IEEE 802.3 interface.
1 Serial network interface.
32K bytes of non-volatile configuration memory.
4096K bytes of flash memory sized on embedded flash.
Configuration register is 0x0
chaos> ^d
NCP> EXIT

Debugging MOP
The EXEC command DEBUG MOP reports events occurring on the MOP server,
including request ID messages received, system ID messages transmitted, and
the reservation and release of the remote console. This command can be used to
debug problems encountered when attempting to connect to a router using MOP.

Example
The following example shows debug output while a user is connecting to a router
using MOP.
muddy-river# debug mop
MOP event debugging is on
muddy-river#
MOP: Reserving console for aa00.0400.9005
MOP(Ethernet0): Got request_id message from aa00.0400.9005
MOP(Ethernet0): Sending sysid message to aa00.0400.9005
MOP: Console released by aa00.0400.9005

Using MOP 5–9

Using MOP
Command Summary

Command Summary
This section lists the commands described in this chapter. Unless otherwise
specified, these are configuration commands.
b mop filename [MAC-address] [interface]
ROM monitor command that boots a system image using MOP. The argument
filename is the name of the file image that is being loaded. The optional
argument MAC-address is the MAC address of the host from which you are
loading the software. The optional argument interface selects the interface
from which to load the software.
copy mop flash
Copies a system image that has been stored on a Digital MOP server into
Flash memory. Note: The DECbrouter 90T must be in bootstrap mode in
order to load the flash.
This is an EXEC command.
debug mop
Enables the output of MOP debugging messages. Used for troubleshooting.
This is an EXEC command.
[no] mop enabled
Enables MOP on an interface. MOP is enabled by default on Ethernet
interfaces and is not enabled on other interfaces. Use the NO MOP
ENABLED command to disable MOP. Once enabled, the MOP server
periodically multicasts a system ID message.
[no] mop retransmit-timer seconds
Sets the time that the router will wait for a response before retransmitting a
message that has not yet been acknowledged. The argument seconds is the
number of seconds to wait and is a number from 1 through 20. The default
value is 4.
[no] mop retries count
Sets the number of times the router will attempt to retransmit an
unacknowledged message before declaring a failure. The argument count
must be a number from 3 through 24 (inclusive). The default value is 8.
[no] mop sysid
Configures an interface for periodic MOP system ID messages. Use the NO
MOP SYSID command to disable MOP from sending the system ID messages.
This lets you use MOP, but does not generate messages used by the MOP
network configurator.

5–10 Using MOP

6
Managing and Monitoring the System
This chapter describes the EXEC commands you use to monitor, manage, and
troubleshoot general system processes and conditions on your DECbrouter 90.
These processes and conditions include:
•

System memory allocator and buffer pools

•

System configuration and processes

•

Stack utilization

•

System error message logs

This chapter also provides a general overview of these system tasks:
•

Using the DEBUG commands to troubleshoot network problems

•

Testing connectivity

•

Tracing routes

•

Testing the system

See the chapters containing information about the interfaces and the protocols
supported by the DECbrouter 90 for descriptions of the interface-specific and
protocol-specific debugging and monitoring commands.
Most of the network management commands are executed at the privileged-level
prompt, although there is a subset of monitoring commands that you can enter at
the user-level prompt.
At the end of the chapter is an alphabetically arranged summary of the
commands it describes.

Monitoring System Processes
Use the EXEC show commands to display data structures, configuration
parameters, and usage statistics for the router. To list all the available SHOW
command options, enter this command at the EXEC prompt.
show ?
Two different lists will be displayed, one at the user-level prompt, and one at the
enabled, privileged-level prompt. The lists include a summary of the command
function for easy reference. See Chapter 2 for the procedure to enter the user and
privileged levels.

Managing and Monitoring the System 6–1

Managing and Monitoring the System
Monitoring System Processes
Displaying Buffer Pool Statistics
The DECbrouter 90 has one pool of queuing elements and five pools of packet
buffers of different sizes. For each pool, the router keeps counts of the number
of buffers outstanding, the number of buffers in the free list, and the maximum
number of buffers allowed in the free list. To display statistics for the buffer pools
on the router, use the SHOW BUFFERS command. Enter this command at the
EXEC prompt:
show buffers [interface]
The optional argument interface causes a search of all buffers that have been
associated with that interface for longer than one minute. The contents of these
buffers are printed to the screen. This option is useful in diagnosing problems
where the input queue count on an interface is consistently nonzero.
Following is sample output without the optional interface argument. Table 6–1
describes the fields.
Buffer elements:
250 in free list (250 max allowed)
10816 hits, 0 misses, 0 created
Small buffers, 104 bytes (total 120, permanent 120):
120 in free list (0 min, 250 max allowed)
26665 hits, 0 misses, 0 trims, 0 created
Middle buffers, 600 bytes (total 90, permanent 90):
90 in free list (0 min, 200 max allowed)
5468 hits, 0 misses, 0 trims, 0 created
Big buffers, 1524 bytes (total 90, permanent 90):
90 in free list (0 min, 300 max allowed)
1447 hits, 0 misses, 0 trims, 0 created
Large buffers, 5024 bytes (total 0, permanent 0):
0 in free list (0 min, 100 max allowed)
0 hits, 0 misses, 0 trims, 0 created
Huge buffers, 12024 bytes (total 0, permanent 0):
0 in free list (0 min, 30 max allowed)
0 hits, 0 misses, 0 trims, 0 created
0 failures (0 no memory)

6–2 Managing and Monitoring the System

Managing and Monitoring the System
Monitoring System Processes
Table 6–1 Show Buffers Field Descriptions
Field

Description

Buffer elements

Blocks of memory used in internal operating system
queues

Small buffers
Middle buffers
Big buffers

Blocks of memory used to hold network packets

Large buffers
Huge buffers
Hits

Count of successful attempts to allocate a buffer when
needed

Misses

Count of allocation attempts that failed for lack of a
free buffer in the pool

Created

Count of new buffers created

Trims

Count of buffers destroyed

In free list

Number of buffers of a given type that are not
currently allocated and are available for use

Max allowed

Maximum number of buffers of a given type allowed in
the system

Failures

Total number of allocation requests that have failed
for lack of a free buffer

No memory

Number of failures due to a lack of memory to create a
new buffer

Displaying System Memory Statistics
To show statistics about the memory, use the SHOW MEMORY command. Enter
this command at the EXEC prompt:
show memory

This command displays memory-free pool statistics. These statistics include
summary information about the activities of the system memory allocator and a
block-by-block listing of memory use. Sample output follows. Table 6–2 describes
the fields; Table 6–3 lists the characteristics of each block of memory in the
system.
Head
Processor 148B8C
Address
148B8C
14B27C
14B2E0
14B378
14B558
14B5F8
14B6BC

Free Start
1D66B0

Bytes Prev.
916 0
100 14AA94
152 14B27C
480 14B2E0
100 14B378
72 14B5BC
88 14B688

Total Bytes
2847860

Used Bytes
561252

Next
Free? PrevF NextF
148F20
14B2E0
14B378
14B558
y 1CE270 1CA938
14B5BC
14B640
14B714

Alloc PC
7B8E
3F2FE
1DBC
5E85A
57A8E
7B830
C724C

Free Bytes
2286608
What
*Init*
Logger
Router Init
IGRP Router
DECnet Input
XNS Router
Virtual Exec

Managing and Monitoring the System 6–3

Managing and Monitoring the System
Monitoring System Processes
Table 6–2 Show Memory Field Descriptions
Field

Description

Head

Hexadecimal address of the head of the memory allocation chain

Free start

Hexadecimal address of the base of the free list

Total bytes

Total amount of system memory

Used bytes

Amount of memory in use

Free bytes

Amount of memory not in use

Table 6–3 Characteristics of Each Block of Memory
Field

Description

Address

Hexadecimal address of block

Bytes

Size of block in bytes

Address of previous block (should match address on previous line)

Address of next block (should match address on next line)

Free?

Tells whether the block is free

Alloc PC

Address of the system call that allocated the block

What

Name of process that owns the block

Displaying Active System Processes
To see information about the active processes, use the SHOW PROCESSES
command. Enter this command at the EXEC prompt:
show processes
Following is a partial display of the command output. Table 6–4 describes the
fields.
CPU utilization for five seconds: 19%; one minute: 12%; five minutes: 12%
PID Q T
PC Runtime (ms)
1 M E 17518
40072
2 M E 5040
932
32 M E 4C390
73012
4 M E 22984
172
5 H E 5040
100324
6 M E 21278
12188
7 M E 32F32
32
8 L E 33C1E
508
9 L E 5040
1104
10 L E 5040
352
11 H E 5040
2636
12 M T 2CF2
36976
13 H E 5040
0
14 M E 44AE4
21964

6–4 Managing and Monitoring the System

Invoked
830
11
6141
252
66619
22451
10926
28
935
458
9077
49175
2
18029

uSecs Stacks
48279 606/800
84727 486/800
11889 480/800
682 662/800
1505 606/900
542 508/800
2 592/800
18142 576/800
1180 666/800
768 674/800
290 710/800
751 602/800
0 852/900
1218 742/900

TTY Process
0 Net Background
0 Logger
0 IGRP Router
0 BOOTP Server
0 IP Input
0 IP Protocols
0 TCP Timer
0 TCP Protocols
0 ARP Input
0 Probe Input
0 Net Input
0 TTY Background
0 DECnet Input
0 DECnet Routing

Managing and Monitoring the System
Monitoring System Processes
Table 6–4 Show Processes Field Descriptions
Field

Description

CPU utilization

Ratio of current idle time over the longest idle time. Gives the
user a general idea of how busy the processor is.

PID

Process ID

Process queue priority (high, medium, low)

Scheduler test (Event, Time, Suspended)

Current program counter

Runtime (ms)

CPU time the process has used, in milliseconds

Invoked

Number of times the process has been invoked

uSecs

Microseconds of CPU time for each invocation

Stacks

Low water mark/Total stack space available

TTY

Terminal that controls the process

Process

Name of process

Note
Because the router has a 4-millisecond clock resolution, run times are
considered reliable only after a large number of invocations or after a
reasonable, measured run time.

Displaying Memory Utilization
To show memory utilization, use the SHOW PROCESSES MEMORY command.
Enter this command at the EXEC prompt:
show processes memory
The SHOW PROCESSES MEMORY command monitors the memory utilization
of processes. The following is a display of sample output. Table 6–5 describes the
fields.
Total: 2416588, Used: 530908, Free: 1885680
PID TTY Allocated
Freed
Holding Process
0
0
462708
2048
460660 *Init*
0
0
76
4328 4252 *Sched*
0
0
82732
33696
49036 *Dead*
1
0
2616
0
2616 Net Background
2
0
0
0
0 Logger
21
0
20156
40
20116 IGRP Router
4
0
104
0
104 BOOTP Server
5
0
0
0
0 IP Input
6
0
0
0
0 TCP Timer
7
0
360
0
360 TCP Protocols
8
0
0
0
0 ARP Input
9
0
0
0
0 Probe Input
10
0
0
0
0 MOP Protocols
11
0
0
0
0 Timers
12
0
0
0
0 Net Input
530936 Total

Managing and Monitoring the System 6–5

Managing and Monitoring the System
Monitoring System Processes
Table 6–5 Show Processes Memory Field Descriptions
Field

Description

PID

Process ID

TTY

Terminal that controls the process

Allocated

Sum of all memory that process has requested from the system

Freed

Amount of memory a process has returned to the system

Holding

Allocated memory minus freed memory; can be negative when it
has freed more than it was allocated

Process

Process name

*Init*

System initialization

*Sched*

The scheduler

*Dead*

Processes as a group that are now dead

Total

Total amount of memory held

Displaying Stack Utilization
To show stack utilization, use the SHOW STACKS command. Enter this
command at the EXEC prompt:
show stacks
The SHOW STACKS command monitors the stack utilization of processes and
interrupt routines. Its display includes the reason for the last system reboot. If
the system was reloaded because of a system failure, a saved system stack trace
is displayed. This information can be useful for analyzing crashes in the field.

Displaying the System Configuration
To display the contents of the nonvolatile memory, if present and valid, use the
SHOW CONFIGURATION command. Enter this command at the EXEC prompt:
show configuration
The nonvolatile memory stores the configuration information in the router in text
form as configuration commands.

Displaying the Error Logging Conditions
To show the state of logging (syslog), use the SHOW LOGGING command. Enter
this command at the EXEC prompt:
show logging
This command displays the state of syslog error and event logging, including host
addresses, and whether console logging is enabled. This command also displays
simple network management protocol (SNMP) configuration parameters and
protocol activity. See the section Redirecting System Error Messages in Chapter 4
for an explanation of how to configure message logging. Following is a sample
output. Table 6–6 describes the fields.

6–6 Managing and Monitoring the System

Managing and Monitoring the System
Monitoring System Processes
Syslog logging: enabled
Console logging: disabled
Monitor logging: level debugging, 266 messages logged.
Trap logging: level informational, 266 messages logged.
Logging to 131.108.2.238
SNMP logging: disabled, retransmission after 30 seconds
0 messages logged
Table 6–6 Show Logging Field Descriptions
Field

Description

Syslog logging

When enabled, system logging messages are sent to
a UNIX host that acts as a syslog server; that is, it
captures and saves the messages.

Console logging

If enabled, states the level; otherwise this field
displays disabled.

Monitor logging

The minimum level of severity required for a log
message to be sent to a monitor terminal (not the
console).

Trap logging

The minimum level of severity required for a log
message to be sent to syslog server.

SNMP logging

Shows whether SNMP logging is enabled, the number
of messages logged, and the retransmission interval.

Displaying Protocol Information
To display the configured protocols, use the SHOW PROTOCOLS command.
Enter this command at the EXEC prompt:
show protocols
The command shows the global and interface-specific status of any configured
Level 3 protocol; for example, IP, DECnet, Novell and AppleTalk. The following is
sample output:
Global values:
Internet Protocol routing is enabled
DECNET routing is enabled
XNS routing is enabled
Appletalk routing is enabled
X.25 routing is enabled
Ethernet 0 is up, line protocol is up
Internet address is 131.108.1.1, subnet mask is 255.255.255.0
Decnet cost is 5
XNS address is 2001.AA00.0400.06CC
AppleTalk address is 4.129, zone Twilight
Serial 0 is up, line protocol is up
Internet address is 192.31.7.49, subnet mask is 255.255.255.240
Serial 1 is down, line protocol is down
Internet address is 192.31.7.177, subnet mask is 255.255.255.240
AppleTalk address is 999.1, zone Magnolia Estates

Managing and Monitoring the System 6–7

Managing and Monitoring the System
Troubleshooting Network Operations

Troubleshooting Network Operations
The DECbrouter 90 includes software to aid in tracking down problems with
the router or with other hosts on the network. The privileged EXEC command
DEBUG enables the display of several classes of network events on the console
terminal. The privileged UNDEBUG command turns off the display of these
classes. The EXEC command SHOW DEBUGGING displays the state of each
debugging option.
show debugging
See the section Redirecting System Error Messages in Chapter 4 for an
explanation of how to configure message logging.
Note
The system gives high priority to debugging output. For this reason,
debugging commands should be turned on only for troubleshooting specific
problems or during troubleshooting sessions with Digital staff. Excessive
debugging output can render the system unusable.
To list and briefly describe all the DEBUG command options, enter the DEBUG ?
command at the privileged-level EXEC prompt.
debug ?
This section provides an overview of how to use the debugging commands.
See the interface and protocol-specific chapters of this manual for the DEBUG
command descriptions.
To turn on all system diagnostics, enter this command at the EXEC prompt:
debug all
Its converse, the UNDEBUG ALL command, turns off all diagnostic output.

Real-time Debugging Support
Time-stamping enhances real-time debugging by providing the relative timing
of logged events. This information is especially useful when you send debugging
output to Digital for assistance.
To configure the system for time-stamping, use the global command:
[no] service timestamps
Note
Unsolicited error messages are not time-stamped; this features applies
only to messages resulting from the DEBUG command.
When debugging is enabled, the resulting messages are preceded by a timestamp when they are sent to monitor terminals. The time-stamp is the format
HHHH:MM:SS and indicates the time since the router was last rebooted.

6–8 Managing and Monitoring the System

Managing and Monitoring the System
Real-time Debugging Support
Example
This example shows the command to enter configuration mode and the
configuration command that implements the time-stamping of debugging events.
gw# configure
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
service timestamps

Example
In this example, debugging modem events is activated, events are logged, and
time-stamping occurs, indicating the relative time the event is logged based on
the time since the router was last rebooted. The TTY4 asserting DTR event
occurred 3 minutes and 48 seconds after the router was last rebooted
gw# debug modem
RS-232 modem signal debugging is on
cs# cs 4004
Trying RUBBLE.DEC.COM (16.108.61.34, 4004)....Open
TTY4: asserting DTR
[Connection to cs closed by foreign host]
cs#
TTY4: timed out waiting for CTS
TTY4: dropping DTR, hanging up
cs# configure
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
service timestamps
%SYS-5-CONFIG_I: Configured from console by console ()
cs# cs 4004
Trying RUBBLE.DEC.COM (16.108.61.34, 4004)...Open
0:03:48: TTY4 asserting DTR
[Connection to RUBBLE closed by foreign host]
cs#

Managing and Monitoring the System 6–9

Managing and Monitoring the System
Real-time Debugging Support

Example
In the following example, the ARP events occurred 52 minutes and 51 seconds
after reload.
gw# debug arp
ARP packet debugging is on
IP ARP: sent req src 131.108.61.37 0000.0c01.f0fe, dst 131.108.19.40
0000.0000.0000
IP ARP: rcvd rep src 131.108.19.40 0000.0c01.0e3b, dst 131.108.61.37
ARP: (merge) Creating entry for IP addr: 131.108.19.40, hw: 0000.0c01.0e3b
cs# configure
Enter configuration commands, one per line.
Edit with DELETE, CTRL/W, and CTRL/U; end with CTRL/Z
service timestamp
^Z
cs#
%SYS-5-CONFIG_I: Configured from console by console ()
0:52:51: IP ARP: sent req src 131.108.61.37 0000.0c01.f0fe,
dst 131.108.19.33 0000.0000.0000
0:52:51: IP ARP: rcvd rep src 131.108.19.33 0000.0c01.0e3b,
dst 131.108.61.37
0:52:51: ARP: (merge) Creating entry for IP addr: 131.108.19.33,
hw: 0000.0c01.0e3b

Testing Connectivity with the PING Command
As an aid to diagnosing basic network connectivity, many network protocols
support the packet internet groper (ping) program, which sends an echo request
packet to an address, then awaits a reply. Results from this echo protocol can
help in evaluating the path-to-host reliability, delays over the path, and whether
the host can be reached or is functioning.
Note
Not all hosts support pings for all protocols.
To implement this program, use the privileged EXEC command PING. When the
PING command is entered, the system issues a prompt for one of the following
protocol keywords— appletalk, clns, ip, novell, pup, or xns.
The default protocol is IP. After determining the protocol type, the PING
command prompts for an address or host name, repeat count (default is 5),
datagram size (default is 100 bytes), time-out interval (default is 2 seconds), and
extended commands (default is none). The precise dialog varies from protocol to
protocol.
If a host name or address is typed on the same line as the EXEC PING command,
the default action is taken as appropriate for the protocol type of that name or
address.
The PING command uses the exclamation point (!) and period (.) in its display.
Each exclamation point indicates receipt of a reply. A period (.) indicates that the
router timed out while waiting for a reply. Other characters may appear in the
ping output display, depending on the protocol type. The output concludes with
the success rate and minimum, average, and maximum round-trip times.

6–10 Managing and Monitoring the System

Managing and Monitoring the System
Testing Connectivity with the PING Command
To abort a ping session, type the escape sequence (by default, Ctrl/^ X, which
is done by simultaneously pressing the Ctrl, shift, and 6 keys, letting go, then
pressing the X key).
Sample displays and tips for using these protocols are included in the chapters
describing the protocols supported by the DECbrouter 90 PING command.

Checking Routes with the TRACE Command
The TRACE command is a useful debugging command that allows the network
administrator to discover the routes that packets actually will take when
traveling to their destinations. The TRACE command supports ip, clns, and
vines route tracing.
trace [destination]
To invoke a simple trace test, enter the destination address or host name on the
command line. The default parameters for the appropriate protocol are assumed,
and the tracing action begins.
To use nondefault parameters and invoke an extended trace test, enter the
command without a destination argument. You will be stepped through a dialog
to select the desired parameters.
Typing the escape sequence (by default, Ctrl/^ X, which is done by simultaneously
pressing the Ctrl, shift, and 6 keys, letting go, then pressing the X key)
terminates a TRACE command. See the DECbrouter 90 Products, Configuration
and Reference, Volume 2 and the DECbrouter 90 Products, Configuration and
Reference, Volume 3 respectively, for more information about using this command.

Writing System Configuration Information
This section describes the privileged WRITE commands used to manage the
system configuration information.
To erase the configuration information, use the following EXEC command. This
command erases the configuration information in the nonvolatile memory. This
command does not affect the configuration in use.
write erase
To copy the configuration to memory, use the following EXEC command. This
command copies the current configuration information to the nonvolatile memory.
write memory
To copy the configuration to the network, use the following EXEC command. This
command sends a copy of the current configuration information to a server host.
You are prompted for a destination host and a file name.
write network

Managing and Monitoring the System 6–11

Managing and Monitoring the System
Writing System Configuration Information
To write the configuration on the terminal, use the following EXEC command.
This command displays the current configuration information on the terminal.
write terminal

Testing the System
Included as part of the EXEC command set are commands that allow testing of
system interfaces and memory.
Note
Digital does not recommend using these commands; they are intended to
aid Digital manufacturing staff in checking out system functionality.
The following EXEC command is used to test the system interfaces:
test interfaces
The EXEC TEST INTERFACES command is intended for the factory checkout
of network interfaces. It is not intended for diagnosing problems with an
operational router. The TEST INTERFACES output does not report correct
results if the router is attached to a "live" network. For each network interface
that has an IP address that can be tested in loopback (all serial interfaces), the
TEST INTERFACE command sends a series of ICMP echoes. Error counters are
examined to determine the operational status of the interface.

EXEC System Management Command Summary
This section lists all the EXEC system management and user commands in
alphabetical order.
debug ?
Lists and briefly describes all the DEBUG command options.
[un]debug all
Enables all diagnostic output. Its converse, the UNDEBUG ALL command,
turns off all diagnostic output.
ping
Provides a diagnostic tool for testing connectivity. Results help evaluate
path-to-host reliability, delays over the path, and whether the host is
functioning.

6–12 Managing and Monitoring the System

Managing and Monitoring the System
EXEC System Management Command Summary
[no] service timestamps
Enhances real-time debugging by providing the relative timing of logged
events. This information is especially useful when you send debugging output
to Digital technical support personnel for assistance.
show ?
Lists all the SHOW command options. Two lists can be displayed: one at the
user-level prompt and one at the enabled, privileged-level prompt.
show buffers [interface]
Displays statistics for the buffer pools on the DECbrouter 90. The router has
one pool of queuing elements and five pools of packet buffers of different sizes.
For each pool, the router keeps counts of the number of buffers outstanding,
the number of buffers in the free list, and the maximum number of buffers
allowed in the free list. With the optional argument interface, this command
searches all buffers that have been associated with the interface for longer
than one minute.
show configuration
Displays the contents of the nonvolatile memory, if present and valid. The
nonvolatile memory stores the configuration information in the DECbrouter
90 in text form as configuration commands.
show debugging
Displays the current settings of the debug command options.
show flash
Displays the total amount of flash memory present, any files that may
currently exist in flash memory, and the amounts of flash memory used and
remaining.

Managing and Monitoring the System 6–13

Managing and Monitoring the System
EXEC System Management Command Summary
show flash all
Displays all the output of show flash; also shows information about each
Flash memory device. Must be in the bootstrap mode to see the full output.

show logging
Displays the state of syslog error and event logging, including host addresses
and whether console logging is enabled. This command also displays SNMP
configuration parameters and protocol activity.

show memory
Displays memory-free pool statistics. These statistics include summary
information about the activities of the system memory allocator and a
block-by-block listing of memory use.
show processes
Displays information about all active processes.
show process memory
Displays information about memory utilization.
show protocols
Displays the global and interface-specific status of any configured level 3
protocol.
show stacks
Monitors the stack utilization of processes and interrupt routines. Its display
includes the reason for the last system reboot. If the system was reloaded
because of a system failure, a saved system stack trace is displayed. This
information can be useful to support staff for analyzing crashes in the field.

6–14 Managing and Monitoring the System

Managing and Monitoring the System
EXEC System Management Command Summary
test interfaces
Intended for the factory checkout of network interfaces. It is not intended for
diagnosing problems with an operational router.
trace [destination]
Allows the network administrator to discover the routes that packets actually
will take when traveling to their destinations. The TRACE command
supports IP, CLNS, and VINES route tracing. Typing the escape sequence
terminates TRACE.

write erase
Erases the configuration information in the nonvolatile memory. This
command does not affect the configuration in use.

write memory
Copies the current configuration information to the nonvolatile memory.
write network
Sends a copy of the current configuration information to a server host. You
are prompted for a destination host and a file name.
write terminal
Displays the current configuration information.

Managing and Monitoring the System 6–15

7
Configuring the Interfaces
This chapter contains information on enabling, shutting down, and displaying
messages pertinent to interface configuration and operation. Also discussed are
the procedures and command descriptions for configuring and maintaining the
following router interface components:
•

Serial interfaces

•

Ethernet interfaces

You also will find information about configuring the serial Dial Backup feature
and learn how to configure a null interface and the point-to-point protocol (PPP)
and HDLC.
To enable an interface, you must be in the configuration command collection
mode. To enter this mode, enter the EXEC command CONFIGURE at the EXEC
prompt. Once in the command collection mode, start configuring the interface by
entering the INTERFACE command. When the interface is configured, you can
check its status by entering EXEC SHOW commands at the EXEC prompt.
This chapter provides software configuration information only. For hardware
technical descriptions, and for information about installing these interfaces, refer
to the appropriate hardware installation and maintenance publication.
Summaries of the interface configuration commands and EXEC monitoring
commands described in this chapter are included at the end of the chapter.

Specifying an Interface
Enter the INTERFACE global configuration command in configuration mode to
identify a specific network interface (for example, serial port or Ethernet port).
By entering this command you begin the configuration subcommand collection
mode for the specified interface.
The INTERFACE command has the following syntax:
interface type unit
The argument type identifies the interface type; the argument unit identifies
the connector number. Unit numbers are assigned at the factory at the time of
installation or when added to a system and can be displayed with the SHOW
INTERFACES command.

Configuring the Interfaces 7–1

Configuring the Interfaces
Specifying an Interface
Example:
This example begins interface configuration subcommand collection mode for
serial connector 0 (interface serial 0):
interface serial 0
Use the EXEC command SHOW INTERFACES (described later in this chapter)
to determine the interface type and unit numbers.
In the interface configuration subcommand collection mode, you enter the
interface subcommands for your particular routing or bridging protocol. The
interface configuration subcommand collection mode ends when you enter a
command that is not an interface subcommand or when you type the Ctrl/Z
sequence.
Note
All DECbrouter 90 models have one Ethernet interface (Ethernet 0). The
DECbrouter 90T1 has one serial interface (serial 0); the DECbrouter 90T2
and the DECbrouter 90T2A have two serial interfaces (serial 0 and serial
1).

Adding a Descriptive Name to an Interface
To add a descriptive name to an interface, use the DESCRIPTION interface
subcommand.
description name-string
no description
The argument name-string is descriptive text to help you remember what is
attached to this interface. The DESCRIPTION command is meant solely as
a comment to be put in the configuration to help you remember what certain
interfaces are for. The description will appear in the output of the following
commands: SHOW CONFIGURATION, WRITE TERMINAL and SHOW
INTERFACES. The no version removes the name-string.
Example
This example describes a 3174 controller on serial 0:
interface serial 0
description 3174 Controller for test lab

Shutting Down and Restarting an Interface
To disable an interface, use the SHUTDOWN interface subcommand. The full
syntax for this command follows.
shutdown
no shutdown
The SHUTDOWN command disables all functions on the specified interface
and prevents all packet transmission. The command also marks the interface
as unavailable; this information is communicated to other routers through all
7–2 Configuring the Interfaces

Configuring the Interfaces
Shutting Down and Restarting an Interface
dynamic routing protocols. The interface will not be mentioned in any routing
updates. On serial interfaces, this command causes the DTR signal to be dropped.
To restart a disabled interface, use the NO SHUTDOWN interface subcommand.
To check whether an interface is disabled, use the EXEC command SHOW
INTERFACES as described in the next section. An interface that has been shut
down is shown as administratively down in this command’s display:

Examples
This example turns off the interface Ethernet 0:
interface ethernet 0
shutdown
This example turns the interface back on:
interface ethernet 0
no shutdown

Clearing Interface Counters
To clear the interface counters shown with the SHOW INTERFACES command,
enter the following command at the EXEC prompt:
clear counters [type unit]
The command clears all the current interface counters from the interface unless
the optional arguments type and unit are specified to clear only a specific interface
type (serial and Ethernet) from a specific unit or card number.
Note
This command will not clear counters retrieved using SNMP, but only
those seen with the EXEC SHOW INTERFACES command.

Displaying Information About an Interface
The software contains commands that you can enter at the EXEC prompt to
display information about the interface, including the software and hardware
versions, the controller status, and some statistics about the interfaces. These
commands begin with the word "show." (The full list of these commands can be
displayed by entering the command SHOW ? at the EXEC prompt.) A description
of interface-specific SHOW commands follows.

Displaying the System Configuration
The SHOW VERSION command displays the configuration of the system
hardware, the software version, the names and sources of configuration files,
and the boot images. Enter this command at the EXEC prompt:
show version

Configuring the Interfaces 7–3

Configuring the Interfaces
Displaying Information About an Interface
The following shows sample output from this command:
DECbrouter 90 Software (DEWBR), Version 9.14(1)
Copyright (c) 1986-1992 by cisco Systems, Inc.
Compiled Thu 17-Dec-92 13:43
System Bootstrap, Version 4.6
Chrysostom uptime is 2 days, 10 hours, 0 minutes
System restarted by power-on
System image file is "DEWBR", booted through flash
DECbrouter 90 router (68030) processor (revision 0x00) with 1024K/1024K bytes
of memory.
Processor board serial number 00000000
DDN X.25 software.
Bridging software.
SuperLAT software (copyright 1990 by Meridian Technology Corp).
1 Ethernet/IEEE 802.3 interface.
2 Serial network interface.
32K bytes of non-volatile configuration memory.
4096K bytes of flash memory sized on embedded flash.
Configuration register is 0x102
In the output, the first block of text lists information about the system software,
which includes the software release version number. Always specify the complete
version number when reporting a possible software problem. In the sample
output, the version number is 9.14, initial release.
The second block of text lists the system bootstrap version, in this case 4.3.
The third block of text includes the system name and uptime, or the amount of
time the system has been up and running. Also displayed is a log of how the
system was last booted, both as a result of normal system startup and of system
error. For example, information can be displayed to indicate a bus error that is
generally the result of an attempt to access a nonexistent address.
System restarted by bus error at PC0XC4CA address 0X210C0C0
The name of the flash file booted is shown.
The remaining output shows the hardware configuration and any nonstandard
software options. The configuration register contents are displayed in
hexadecimal notation.
Note
The output of the SHOW VERSION EXEC command also can provide
certain messages, such as bus error messages. If such error messages
appear, report the complete text of this message to your Digital technical
support specialist.

Displaying Controller Status
The SHOW CONTROLLERS command displays current internal status
information for different interfaces. Enter this command at the EXEC prompt:
show controllers {serial | ether}

7–4 Configuring the Interfaces

Configuring the Interfaces
Displaying Information About an Interface
Use the following keywords to display the information about each:
•

serial—For the serial interfaces

•

ether—For the Ethernet interface (You may follow the interface command
with a specific interface number.)

Sample output for the Ethernet interface follows.
LANCE unit 0, idb 0x4D764, ds 0x4EDD0, regaddr = 0x2130000, reset_mask 0x4
IB at 0x10BFEC: mode=0x0000, mcfilter 0001/0100/0008/4000
station address 0800.2ba0.b51c default station address 0800.2ba0.b51c
buffer size 1524
RX ring with 16 entries at 0x10C028
Rxhead = 0x10C050 (5), Rxp = 0x4EDFC (5)
00 pak=0x12704C ds=0x127156 status=0x80 max_size=1524 pak_size=87
01 pak=0x12366C ds=0x123776 status=0x80 max_size=1524 pak_size=85
02 pak=0x106F28 ds=0x107032 status=0x80 max_size=1524 pak_size=132
03 pak=0x10C184 ds=0x10C28E status=0x80 max_size=1524 pak_size=132
04 pak=0x1261D4 ds=0x1262DE status=0x80 max_size=1524 pak_size=132
05 pak=0x10ECEC ds=0x10EDF6 status=0x80 max_size=1524 pak_size=132
06 pak=0x125A98 ds=0x125BA2 status=0x80 max_size=1524 pak_size=139
07 pak=0x1067EC ds=0x1068F6 status=0x80 max_size=1524 pak_size=83
08 pak=0x10D738 ds=0x10D842 status=0x80 max_size=1524 pak_size=144
09 pak=0x124C20 ds=0x124D2A status=0x80 max_size=1524 pak_size=132
10 pak=0x11EE14 ds=0x11EF1E status=0x80 max_size=1524 pak_size=132
11 pak=0x12535C ds=0x125466 status=0x80 max_size=1524 pak_size=132
12 pak=0x126910 ds=0x126A1A status=0x80 max_size=1524 pak_size=96
13 pak=0x123DA8 ds=0x123EB2 status=0x80 max_size=1524 pak_size=106
14 pak=0x10DE74 ds=0x10DF7E status=0x80 max_size=1524 pak_size=74
15 pak=0x1060B0 ds=0x1061BA status=0x80 max_size=1524 pak_size=122
TX ring with 4 entries at 0x10C0D8, tx_count = 0
tx_head = 0x10C0E0 (1), head_txp = 0x4EE40 (1)
tx_tail = 0x10C0E0 (1), tail_txp = 0x4EE40 (1)
00 pak=0x000000 ds=0x10BD96 status=0x03 status2=0x0000 pak_size=118
01 pak=0x000000 ds=0x10BD96 status=0x03 status2=0x0000 pak_size=118
02 pak=0x000000 ds=0x10BD96 status=0x03 status2=0x0000 pak_size=118
03 pak=0x000000 ds=0x10BD96 status=0x03 status2=0x0000 pak_size=118
0 missed datagrams, 0 overruns, 0 late collisions, 0 lost carrier events
0 transmitter underruns, 0 excessive collisions, 0 babbles
0 memory errors, 0 spurious initialization done interrupts
Lance csr0 = 0x73
MK5 unit 0, idb 0x4F6AC, ds 0x50D18, regaddr 0x2130040, reset_mask 0x2
IB at 0x117D9C: mode=0x0108, local_addr=0, remote_addr=0
N1=1524, N2=1, scaler=100, T1=1000, T3=2000, TP=1
buffer size 1524
No serial cable attached
RX ring with 16 entries at 0x117DF8 : RLEN=4, Rxhead 0
00 pak=0x117660 ds=0x117774 status=80 max_size=1524 pak_size=0
01 pak=0x116F24 ds=0x117038 status=80 max_size=1524 pak_size=0
02 pak=0x1167E8 ds=0x1168FC status=80 max_size=1524 pak_size=0
03 pak=0x1160AC ds=0x1161C0 status=80 max_size=1524 pak_size=0
04 pak=0x115970 ds=0x115A84 status=80 max_size=1524 pak_size=0
05 pak=0x115234 ds=0x115348 status=80 max_size=1524 pak_size=0
06 pak=0x114AF8 ds=0x114C0C status=80 max_size=1524 pak_size=0
07 pak=0x1143BC ds=0x1144D0 status=80 max_size=1524 pak_size=0
08 pak=0x113C80 ds=0x113D94 status=80 max_size=1524 pak_size=0
09 pak=0x113544 ds=0x113658 status=80 max_size=1524 pak_size=0
10 pak=0x112E08 ds=0x112F1C status=80 max_size=1524 pak_size=0
11 pak=0x1126CC ds=0x1127E0 status=80 max_size=1524 pak_size=0
12 pak=0x111F90 ds=0x1120A4 status=80 max_size=1524 pak_size=0
13 pak=0x111854 ds=0x111968 status=80 max_size=1524 pak_size=0
14 pak=0x111118 ds=0x11122C status=80 max_size=1524 pak_size=0
15 pak=0x1109DC ds=0x110AF0 status=80 max_size=1524 pak_size=0
TX ring with 4 entries at 0x117EA8 : TLEN=2, TWD=7

Configuring the Interfaces 7–5

Configuring the Interfaces
Displaying Information About an Interface
tx_count = 0, tx_head = 0, tx_tail = 0
00 pak=0x000000 ds=0x000000 status=0x38 max_size=1524 pak_size=0
01 pak=0x000000 ds=0x000000 status=0x38 max_size=1524 pak_size=0
02 pak=0x000000 ds=0x000000 status=0x38 max_size=1524 pak_size=0
03 pak=0x000000 ds=0x000000 status=0x38 max_size=1524 pak_size=0
XID/Test TX desc at 0xFFFFFF, status=0x30, max_buffer_size=0, packet_size=0
XID/Test RX desc at 0xFFFFFF, status=0x0, max_buffer_size=0, packet_size=0
Status Buffer at 0x117F58: rcv=0, tcv=0, local_state=0, remote_state=0
phase=0, tac=0, currd=0x00000, curxd=0x00000
bad_frames=0, frmrs=0, T1_timeouts=0, rej_rxs=0, runts=0
0 missed datagrams, 0 overruns, 0 bad frame addresses
0 bad datagram encapsulations, 0 user primitive errors
0 provider primitives lost, 0 unexpected provider primitives
0 spurious primitive interrupts, 0 memory errors, 0 transmitter underruns
mk5025 registers: csr0 = 0x4000, csr1 = 0x0002, csr2 = 0x0511
csr3 = 0x7D9C, csr4 = 0x0000, csr5 = 0x0003
Note
The interface type is only queried at startup. If the hardware changes
subsequent to initial startup, the wrong type is reported. This has no
adverse effect on the operation of the software. For instance, if a DCE
cable is connected to a dual-mode V.35 interface after the unit has been
booted, the display presented for show interfaces incorrectly reports
attachment to a DTE device, although the software recognizes the DCE
interface and behaves accordingly.

Displaying Interface Statistics
The software also provides the SHOW INTERFACES command, which displays
statistics for the network interfaces on the router. Enter the following command
at the EXEC prompt:
show interfaces [type unit] [accounting]
Specify the optional arguments type and unit to display statistics for a particular
network interface. The argument type can be one of the following: ethernet or
serial. Use the argument unit to specify the interface unit number.
The optional keyword accounting displays the number of packets of each
protocol type that has been sent through the interface. You can show these
numbers for all interfaces, or you can specify a specific type and unit.
Except for protocols that are encapsulated inside other protocols, such as IP over
X.25, the accounting option also shows the total of all bytes sent and received,
including the MAC header. For example, it totals the size of the Ethernet packet
or the size of a packet that includes HDLC encapsulation.
Table 7–1 lists the protocols for which per-packet accounting information is kept.

7–6 Configuring the Interfaces

Configuring the Interfaces
Displaying Information About an Interface
Table 7–1 Per-Packet Counted Protocols
Protocol

Notes

n/a

DECnet

n/a

XNS

n/a

CLNS

n/a

AppleTalk

n/a

Novell

n/a

Apollo

n/a

VINES

n/a

Trans. Bridge

n/a

SR Bridge

n/a

Chaos

n/a

Xerox PUP

n/a

Digital MOP

The routers use MOP packets to advertise their existence
to Digital machines that use the MOP protocol. A router
periodically broadcasts MOP packets to identify itself as a
MOP host. This results in MOP packets being counted, even
when DECnet is not being actively used.

LAN Manager

LAN Network Manager and IBM Network Manager

Spanning Tree

n/a

ARP

For IP, Chaos, Apollo, Frame relay, SMDS

HP Probe

n/a

Serial Tunnel

SDLC

The SHOW INTERFACE command is used frequently while configuring and
monitoring modules.
For further explanations and examples about specific interfaces, refer to the
following sections in this chapter: Monitoring the Serial Interface and Monitoring
the Ethernet Interface.

Serial Interface Support
This section describes how to specify, maintain, monitor, and debug the serial
interface. This section also describes methods of serial encapsulation.

Specifying a Serial Interface
To specify a serial interface, use this configuration command:
interface serial unit
Specify the serial interface connector number with the argument unit.
Follow this command with the routing or bridging interface subcommands for
your particular protocol or application, as described later in this manual.
The serial interfaces can query the cables to determine their types. However, they
do so only at system startup, so the cables must be attached when the system is
started. Issue a SHOW CONTROLLERS SERIAL command to determine how

Configuring the Interfaces 7–7

Configuring the Interfaces
Serial Interface Support
the serial card has identified them. The command also will show the capabilities
of the serial card and report controller-related failures.

Example
This command begins configuration on interface serial 0:
interface serial 0

Serial Encapsulation Methods
The serial interfaces support the following kinds of serial encapsulations:
•

High-level data link control (HDLC)

•

HDLC distant host (HDH)

•

Frame relay

•

Point-to-point protocol (PPP)

•

Synchronous data link control (SDLC)

•

Switched multimegabit data services (SMDS)

•

Cisco serial tunnel (STUN)

•

X.25-based encapsulations

With the exception of the PPP and HDLC encapsulations, these serial
encapsulation methods are described in Chapter 9. The HDLC serial
encapsulation method is described in this section. PPP serial encapsulation
is described later in the section Configuring the Point-to-Point Protocol.
Change the encapsulation method by using the interface configuration
subcommand ENCAPSULATION, followed by a keyword that defines the
encapsulation method.
encapsulation encapsulation-type
The encapsulation-type argument is a keyword that identifies one of the following
serial encapsulation types that the software supports:
•

bfex25—Blacker front end encryption X.25 operation

•

ddnx25-dce—DDN X.25 DCE operation

•

ddnx25—DDN X.25 DTE operation

•

frame-relay—Frame relay

•

hdh—HDH protocol

•

hdlc—HDLC protocol

•

lapb-dce—X.25 LAPB DCE operation

•

lapb—X.25 LAPB DTE operation

•

multi-lapb-dce—X.25 LAPB multiprotocol DCE operation

•

multi-lapb—X.25 LAPB multiprotocol DTE operation

•

ppp—Point-to-point protocol (PPP)

•

sdlc-primary—IBM serial SNA

7–8 Configuring the Interfaces

Configuring the Interfaces
Serial Interface Support
•

sdlc-secondary—IBM serial SNA

•

smds—SMDS service

•

stun—STUN protocol functions

•

x25-dce—X.25 DCE operation

•

x25—X.25 DTE operation

HDLC Serial Encapsulation Method
The DECbrouter 90 provides HDLC serial encapsulation for serial lines. This
encapsulation method provides the synchronous framing and error detection
functions of HDLC without windowing or retransmission. Although HDLC is the
default serial encapsulation method, it can be reinstalled using the hdlc keyword
with the ENCAPSULATION command as follows:
encapsulation hdlc

Maintaining the Serial Interface
Use the command CLEAR INTERFACE to reset the hardware logic on an
interface. Enter this command at the EXEC prompt:
clear interface type unit

The arguments type and unit specify a particular interface type and its unit
number. In this case, the argument type is serial.
Note
Under normal circumstances, you do not need to clear the hardware logic
on interfaces.

Monitoring the Serial Interface
In general, use the command SHOW INTERFACES to display information about
the serial interface. Enter this command at the EXEC prompt:
show interfaces [type unit] [accounting]

The argument type is specified as serial and unit is the interface unit number.
If you do not provide values for the parameters type and unit, the command
will display statistics for all the network interfaces. The optional keyword
accounting displays the number of packets of each protocol type that have been
sent through the interface.
Sample outputs of this command for HDLC synchronous serial interfaces follows.
Table 7–2 describes the fields.

Configuring the Interfaces 7–9

Configuring the Interfaces
Serial Interface Support

Chrysostom> show interfaces serial 0
Serial 0 is up, line protocol is up
Hardware is MK5025
Internet address is 150.136.190.203, subnet mask is 255.255.255.0
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 0:00:07, output 0:00:00, output hang never
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
Five minute input rate 0 bits/sec, 0 packets/sec
Five minute output rate 0 bits/sec, 0 packets/sec
16263 packets input, 1347238 bytes, 0 no buffer
Received 13983 broadcasts, 0 runts, 0 giants
2 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort
22146 packets output, 2383680 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets, 0 restarts
1 carrier transitions
When you use the accounting option, only the accounting statistics are displayed.

Chrysostom> show interfaces serial 0 accounting
Serial0
Protocol
Pkts In Chars In Pkts Out Chars Out
IP
7344
4787842
1803
1535774
Appletalk
33345
4797459
12781
1089695
DEC MOP
0
0
127
9779
ARP
7
420
39
2340

7–10 Configuring the Interfaces

Configuring the Interfaces
Serial Interface Support
Table 7–2 Show Interfaces Serial Field Descriptions
Field

Description

Serial ... is {up | down}...is
administratively down

Gives the interface unit number and whether
the interface hardware is currently active
(whether carrier detect is present) or if it has
been taken down by an administrator

Line protocol is {up | down |
administratively down}

Tells whether the software processes that
handle the line protocol consider the line
usable (are keepalives successful?) or if it has
been taken down by an administrator.

Hardware is

Specifies the hardware type.

Internet address is

Specifies the Internet address and subnet
mask

MTU

Maximum transmission unit of the interface.

Bandwidth of the interface in kilobits per
second.

DLY

Delay of the interface in microseconds.

Rely

Reliability of the interface as a fraction of 255
(255/255 is 100% reliability), calculated as an
exponential average over five minutes.

Load

Load on the interface as a fraction of 255 (255
/255 is completely saturated), calculated as an
exponential average over five minutes.

Encapsulation

Encapsulation method assigned to interface.

Loopback

Tells whether loopback is set.

Keepalive

Tells whether keepalives are set.

Last input

The number of hours, minutes, and seconds
since the last packet was successfully received
by an interface. Useful for knowing when a
dead interface failed.

Output hang

The number of hours, minutes, and seconds
(or never) since the interface was last reset
because of a transmission that took too long.
When the number of hours in any of the "last"
fields exceeds 24 hours, the number of days
and hours is printed. If that field overflows,
asterisks are printed.

Output queue, input queue, drops

Number of packets in output and input
queues. Each number is followed by a slash,
the maximum size of the queue, and the
number of packets dropped due to a full
queue.

Five-minute input rate; five-minute
output rate

The average number of bits and packets
transmitted per second in the last five
minutes.

packets input
Received...
broadcasts

The total number of error-free packets
received by the system.
The total number of broadcast or multicast
packets received by the interface.
(continued on next page)

Configuring the Interfaces 7–11

Configuring the Interfaces
Serial Interface Support
Table 7–2 (Cont.) Show Interfaces Serial Field Descriptions
Field

Description

runts

The number of packets that are discarded
because they are smaller than the medium’s
minimum packet size.

giants

The number of packets that are discarded
because they exceed the medium’s maximum
packet size.

input error

The total number of no buffer, runts, giants,
CRCs, frame, overrun, ignored, and abort
counts. Other input-related errors also can
increment the count, so this sum may not
balance with the other counts.

CRC

The cyclic redundancy checksum generated by
the originating station or far-end device does
not match the checksum calculated from the
data received. On a serial link, CRCs usually
indicate noise, gain hits, or other transmission
problems on the data link.

frame

The number of packets received incorrectly
having a CRC error and a noninteger number
of octets. On a serial line, this is usually the
result of noise or other transmission problems.

overrun

The number of times the serial receiver
hardware was unable to hand received data
to a hardware buffer because the input rate
exceeded the receiver’s ability to handle the
data.

ignored

The number of received packets ignored by the
interface because the interface hardware ran
low on internal buffers. Broadcast storms and
bursts of noise can cause the ignored count to
be increased.

abort

An illegal sequence of one bits on a serial
interface. This usually indicates a clocking
problem between the serial interface and the
data link equipment.

packets output

Total number of messages transmitted by the
system.

bytes output

Total number of bytes, including data and
MAC encapsulation, transmitted by the
system.

Underruns

Number of times that the transmitter has
been running faster than the router can
handle. This may never be reported on some
interfaces.
(continued on next page)

7–12 Configuring the Interfaces

Configuring the Interfaces
Serial Interface Support
Table 7–2 (Cont.) Show Interfaces Serial Field Descriptions
Field

Description

Output errors

The sum of all errors that prevented the final
transmission of datagrams out of the interface
being examined. Note that this may not
balance with the sum of the enumerated
output errors, as some datagrams may
have more than one error, and others may
have errors that do not fall into any of the
specifically tabulated categories.

interface resets

The number of times an interface has been
completely reset. This can happen if packets
queued for transmission were not sent within
several seconds’ time. On a serial line, this
can be caused by a malfunctioning modem
that is not supplying the transmit clock
signal or by a cable problem. If the system
notices that the carrier detect line of a serial
interface is up but the line protocol is down, it
periodically resets the interface in an effort to
restart it. Interface resets also can occur when
an interface is looped back or shut down.

restarts

The number of times the controller was
restarted because of errors.

carrier transitions

The number of times the carrier detect signal
of a serial interface has changed state.
Indicates modem or line problems if the
carrier detect line is changing state often.

Protocol

The protocol that is operating on the interface.

Pkts In

The number of packets received for that
protocol.

Chars In

The number of characters received for that
protocol.

Pkts Out

The number of packets transmitted for that
protocol.

Chars Out

The number of characters transmitted for that
protocol.

Debugging the Serial Interface
Use the commands DEBUG SERIAL-INTERFACE and DEBUG SERIAL-PACKET
to debug serial interface events. The EXEC commands are as follows:
debug serial-interface
debug serial-packet
Use DEBUG SERIAL-PACKET for detailed debugging information and DEBUG
SERIAL-INTERFACE for more general information.
Use UNDEBUG SERIAL-INTERFACE and UNDEBUG SERIAL-PACKET to turn
off messaging from these DEBUG commands.

Configuring the Interfaces 7–13

Configuring the Interfaces
Ethernet Interface Support

Ethernet Interface Support
The DECbrouter 90 has one built-in Ethernet interface compatible with Ethernet
versions 1 and 2 and the IEEE 802.3 protocol.

Specifying an Ethernet Interface
To specify an Ethernet interface, use this configuration command:
interface ethernet unit
Because the DECbrouter 90 has only one Ethernet interface, use a unit number
of 0.
Follow this command with the routing or bridging interface subcommands for
your particular protocol or application as described later in this manual.

Example
This command begins configuration on interface Ethernet 0.
interface ethernet 0

Ethernet Encapsulation Methods
The Ethernet interface supports a number of encapsulation methods. These
methods are assigned by using the interface subcommand ENCAPSULATION
followed by a keyword that defines the encapsulation method. The encapsulation
method used depends on the protocol. Currently, there are three common
Ethernet encapsulation methods:
•

The standard Ethernet Version 2.0 encapsulation that uses a 16-bit protocol
type code

•

The IEEE 802.3 encapsulation, in which the type code becomes the frame
length for the IEEE 802.2 LLC encapsulation (destination and source Service
Access Points and a control byte)

•

The SNAP method, as specified in RFC 1042, which allows Ethernet protocols
to run on IEEE 802.2 media

The syntax of the ENCAPSULATION command follows.
encapsulation encapsulation-type
The encapsulation-type is one of the following three keywords:
•

arpa—Standard Ethernet Version 2.0 encapsulation

•

iso1—IEEE 802.3 encapsulation

•

snap—IEEE 802.2 Ethernet media

Example
These commands enable standard Ethernet Version 2.0 encapsulation on interface
Ethernet 0:
interface ethernet 0
encapsulation arpa

7–14 Configuring the Interfaces

Configuring the Interfaces
Ethernet Interface Support
Maintaining the Ethernet Interface
Use the command CLEAR INTERFACE to reset the hardware logic on an
interface. Enter this command at the EXEC prompt:
clear interface type unit
The arguments type and unit specify a particular interface type and its unit
number. In this case, the argument type is ethernet.

Note
Under normal circumstances, you do not need to clear the hardware logic
on interfaces.

Monitoring the Ethernet Interface
Use the command SHOW INTERFACES to display information about the
Ethernet interface. Enter this command at the EXEC prompt:
show interfaces [type unit] [accounting]
Where type is the ethernet keyword and unit is the interface unit number. If you
do not provide values for the parameters type and unit, the command will display
statistics for all the network interfaces. The optional keyword accounting
displays the number of packets of each protocol type that have been sent through
the interface.
Sample output of this command follows. Table 7–3 describes the fields.
Chrysostom> show interfaces ethernet 0
Ethernet 0 is up, line protocol is up
Hardware is Lance, address is aa00.0400.0134 (bia 0000.0c00.4369)
Internet address is 131.108.1.1, subnet mask is 255.255.255.0
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, PROBE, ARP Timeout 4:00:00
Last input 0:00:00, output 0:00:00, output hang never
Output queue 0/40, 0 drops; input queue 0/75, 2 drops
Five minute input rate 61000 bits/sec, 4 packets/sec
Five minute output rate 1000 bits/sec, 2 packets/sec
2295197 packets input, 305539992 bytes, 0 no buffer
Received 1925500 broadcasts, 0 runts, 0 giants
3 input errors, 3 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
3594664 packets output, 436549843 bytes, 0 underruns
8 output errors, 1790 collisions, 10 interface resets, 0 restarts
When you use the accounting option, only the accounting statistics are displayed.

Configuring the Interfaces 7–15

Configuring the Interfaces
Ethernet Interface Support
Chrysostom> show interfaces ethernet 0 accounting
Ethernet0
Protocol
Pkts In Chars In Pkts Out Chars Out
IP
7344
4787842
1803
1535774
Appletalk
33345
4797459
12781
1089695
DEC MOP
0
0
127
9779
ARP
7
420
39
2340
Table 7–3 Show Interfaces Ethernet Field Descriptions
Field

Description

Ethernet ... is up ...is administratively
down

Tells whether the interface hardware is
currently active or if it has been taken down
by an administrator.

line protocol is {up | down |
administratively down

Tells whether the software process that
handles the line protocol believes the interface
is usable (are the keepalives successful?)

Hardware

Specifies the hardware type (for example,
Lance) and address.

Internet address

Lists the Internet address followed by subnet
mask

MTU

Maximum transmission unit of the interface.

Bandwidth of the interface in kilobits per
second.

DLY

Delay of the interface in microseconds.

rely

Reliability of the interface as a fraction of 255
(255/255 is 100% reliability), calculated as an
exponential average over five minutes.

load

Load on the interface as a fraction of 255 (255
/255 is completely saturated), calculated as an
exponential average over five minutes.

Encapsulation

Encapsulation method assigned to interface.

loopback

Tells whether loopback is set.

keepalive

Tells whether keepalives are set.

ARP type:

Type of address resolution protocol assigned.

Last input

The number of hours, minutes, and seconds
since the last packet was successfully received
by an interface. Useful for knowing when a
dead interface failed.

output

Number of hours, minutes, and seconds since
the last packet was successfully transmitted
by the interface. Useful for knowing when a
dead interface failed.

output hang

7–16 Configuring the Interfaces

Configuring the Interfaces
Ethernet Interface Support
Table 7–3 (Cont.) Show Interfaces Ethernet Field Descriptions
Field

Description

Last clearing

The time at which the counters that measure
cumulative statistics (such as number of bytes
transmitted and received) shown in this report
were last reset to zero. Note that variables
that might affect routing (for example, load
and reliability) are not cleared when the
counters are cleared.

Output queue, input queue, drops

Number of packets in output and input
queues. Each number is followed by a slash,
the maximum size of the queue, and the
number of packets dropped due to a full
queue.

Five-minute input rate; five-minute
output rate

The average number of bits and packets
transmitted per second in the last five
minutes.

Packets input

The total number of error-free packets
received by the system.

Received ... broadcasts

The total number of broadcast or multicast
packets received by the interface.

Runts

The number of packets that are discarded
because they are smaller than the medium’s
minimum packet size. For instance, any
Ethernet packet that is less than 64 bytes is
considered a runt.

Giants

The number of packets that are discarded
because they exceed the medium’s maximum
packet size. For example, any Ethernet packet
that is greater than 1518 bytes is considered a
giant.

Input error

Includes runts, giants, no buffer, CRC, frame,
overrun, and ignored counts. Other inputrelated errors also can cause the input errors
count to be increased, and some datagrams
may have more than one error; therefore,
this sum may not balance with the sum of
enumerated input error counts.

CRC

The cyclic redundancy checksum generated by
the originating LAN station or far-end device
does not match the checksum calculated from
the data received. On a LAN, this usually
indicates noise or transmission problems on
the LAN interface or the LAN bus itself. A
high number of CRCs is usually the result of
collisions or a station transmitting bad data.

Frame

The number of packets received incorrectly
having a CRC error and a noninteger number
of octets. On a LAN, this is usually the result
of collisions or a malfunctioning Ethernet
device.
(continued on next page)

Configuring the Interfaces 7–17

Configuring the Interfaces
Ethernet Interface Support
Table 7–3 (Cont.) Show Interfaces Ethernet Field Descriptions
Field

Description

Overrun

The number of times the receiver hardware
was unable to hand received data to a
hardware buffer because the input rate
exceeded the receiver’s ability to handle the
data.

Ignored

The number of received packets ignored by
the interface because the interface hardware
ran low on internal buffers. These buffers are
different than the system buffers mentioned
previously in the buffer description. Broadcast
storms and bursts of noise can cause the
ignored count to be increased.

Packets output

Total number of messages transmitted by the
system.

Bytes

Total number of bytes, including data and
MAC encapsulation, transmitted by the
system.

Underruns

Number of times that the transmitter has
been running faster than the router can
handle. This may never be reported on some
interfaces.

Output errors

The sum of all errors that prevented the
final transmission of datagrams out of the
interface being examined. Note that this may
not balance with the sum of the enumerated
output errors, because some datagrams may
have more than one error, and others may
have errors that do not fall into any of the
specifically tabulated categories.

Collisions

The number of messages retransmitted due
to an Ethernet collision. This is usually the
result of an overextended LAN (Ethernet or
transceiver cable too long, more than two
repeaters between stations, or too many
cascaded multiport transceivers). A packet
that collides is counted only once in output
packets.

Interface resets

The number of times an interface has been
completely reset. This can happen if packets
queued for transmission were not sent within
several seconds. On a serial line, this can be
caused by a malfunctioning modem that is not
supplying the transmit clock signal, or by a
cable problem. If the system notices that the
carrier detect line of a serial interface is up,
but the line protocol is down, it periodically
resets the interface in an effort to restart
it. Interface resets also can occur when an
interface is looped back or shut down. restarts
The number of times a type 2 Ethernet
controller was restarted because of errors.

Protocol

The protocol that is operating on the interface.
(continued on next page)

7–18 Configuring the Interfaces

Configuring the Interfaces
Ethernet Interface Support
Table 7–3 (Cont.) Show Interfaces Ethernet Field Descriptions
Field

Description

Pkts In

The number of packets received for that
protocol.

Chars In

The number of characters received for that
protocol.

Pkts Out

The number of packets transmitted for that
protocol.

Chars Out

The number of characters transmitted for that
protocol.

Debugging the Ethernet Interface
Use the command DEBUG BROADCAST to debug MAC broadcast packets. Enter
this command at the EXEC prompt:
debug broadcast
undebug broadcast
Use the UNDEBUG BROADCAST command to turn off messaging.
Use the command DEBUG PACKET to enable a log of packets that the network
is unable to classify. Examples of this are packets with unknown link type or IP
packets with an unrecognized protocol field. Enter this command at the EXEC
prompt:
debug packet
undebug packet
Use the UNDEBUG PACKET command to turn off messaging.

Configuring Dial Backup Service
The dial backup service provides protection against WAN downtime by allowing
you to configure a backup serial line through a circuit-switched connection.
To configure dial backup, associate a secondary serial interface as a backup to a
primary serial interface. This feature requires that an external modem or CSU
/DSU device be connected on the secondary serial interface. The external device
must be capable of responding to a DTR signal (DTR active) by auto-dialing a
connection to a preconfigured remote site.
The dial backup software keeps the secondary line inactive (DTR inactive) until
one of the following conditions is met:
•

The primary line goes down.

•

The transmitted traffic load on the primary line exceeds a defined limit.

These conditions are defined using the interface subcommands described later in
this section.
When the software detects a lost carrier detect signal from the primary line
device or finds that the line protocol is down, it activates DTR on the secondary
line. At that time, the modem or CSU/DSU must be set to dial the remote site.
When that connection is made, the routing protocol defined for the serial line will
continue the job of transmitting traffic over the dialup line.

Configuring the Interfaces 7–19

Configuring the Interfaces
Configuring Dial Backup Service
You also can configure the dial backup feature to activate the secondary line
based upon traffic load on the primary line.
The software monitors the traffic load and computes a five-minute moving
average. If this average exceeds the value you set for the line, the secondary line
is activated, and depending upon how the line is configured, some or all of the
traffic will flow onto the secondary dialup line.
You also can specify a value that defines when the secondary line should be
disabled and the amount of time the secondary line can take going up or down.

Configuring the Dial Backup Line
Use the BACKUP INTERFACE interface subcommands to configure the serial
interface as a secondary, or dial backup, line. The commands have this syntax:
backup interface interface-name
no backup interface interface-name
The argument interface-name specifies the serial port to be set as the secondary
interface line.
Use the NO BACKUP interface command with the appropriate serial port
designation to turn this feature off.

Example
These commands set serial 1 as the backup line to serial 0:
interface serial 0
backup interface serial 1

Defining the Traffic Load Threshold
Use the BACKUP LOAD interface subcommands to set the traffic load thresholds.
The commands have this syntax:
backup load {enable-threshold | never} {disable-load | never}
no backup load {enable-threshold | never} {disable-load | never}
Enter the arguments enable-threshold and disable-load using percentage numbers
representing the load as a percentage of the primary line’s available bandwidth.
When the transmitted or received load on the primary line is greater than the
value assigned to the enable-threshold argument, the secondary line is enabled.
When the transmitted load on the primary line plus the transmitted load on the
secondary line is less than the value entered for the disable-load argument, and
the received load on the primary line plus the received load on the secondary line
is less than the value entered for the disable-load argument, the secondary line is
disabled.
If the never keyword is used instead of a enable-threshold value, the secondary
line is never activated due to load. If the never keyword is used instead of an
disable-load value, the secondary line is never deactivated due to load.
By default, no backup loads are defined.

7–20 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial Backup Service
Example
This example sets the traffic load threshold to 60 percent on the primary
line. When that load is exceeded, the secondary line is activated, and will not
be deactivated until the combined load is less than 5 percent of the primary
bandwidth.
interface serial 0
backup load 60 5

Defining the Backup Line Delay
Use the BACKUP DELAY interface subcommands to define how much time
should elapse before a secondary line is set up or taken down (after a primary
line transitions). The commands have the following syntax:
backup delay {enable-delay | never} {disable-delay | never}
no backup delay {enable-delay | never} {disable-delay | never}
Note
The interval configured with the BACKUP DELAY subcommand does not
affect the operation of the BACKUP LOAD subcommand.

The argument enable-delay is the delay in seconds after the primary line goes
down before the secondary line is activated.
The argument disable-delay is the delay in seconds after the primary line goes up
before the secondary line is deactivated.
When the primary line goes down, the router delays the amount of seconds
defined by the enable-delay argument before enabling the secondary line. If, after
the delay period, the primary line is still down, the secondary line is activated.
When the primary line comes back up, the router will delay the amount of
seconds defined by the disable-delay argument. If the disable-load condition
described previously can be satisfied, or if the secondary is never activated due to
load, then the secondary line also is deactivated.
Note
In cases where there are spurious signal disruptions that may appear as
intermittent lost carrier signals, it is recommended that some delay be
enabled before activating and deactivating a secondary.
Use the never keyword to prevent the secondary line from being activated or
deactivated.
The never version is the default value for backup delay. In order for the
secondary line to be activated when the primary line fails, a backup delay value
must be specified.

Configuring the Interfaces 7–21

Configuring the Interfaces
Configuring Dial Backup Service
Example
This example sets a ten-second delay on deactivating the secondary line; however,
the line is activated immediately.
interface serial 0
backup delay 0 10

Dial Backup Configuration Examples
This section contains three examples of different dial-backup configurations.

Example 1
The following example configures serial 1 as a secondary line that activates
only when the primary line (serial 0) goes down. The secondary line will not be
activated due to load of the primary.
interface serial 0
backup interface serial 1
backup delay 30 60
The secondary line is configured to activate 30 seconds after the primary line goes
down and to remain on for 60 seconds after the primary line is reactivated.

Example 2
The following example configures the secondary line (serial 1) to be activated only
when the load of the primary line reaches a certain threshold.
interface serial 0
backup interface serial 1
backup load 75 5
In this case, the secondary line will not be activated when the primary goes down.
The secondary line will be activated when the load on the primary line is greater
than 75 percent of the primary’s bandwidth. The secondary line will then be
brought down when the aggregate load between the primary and secondary lines
fits within 5 percent of the primary bandwidth.

Example 3
This example configures the secondary line to activate once the traffic threshold
on the primary line exceeds 25 percent.
interface serial 0
backup interface serial 1
backup load 25 5
backup delay 10 60
Once the aggregate load of the primary and the secondary lines return to within
5 percent of the primary bandwidth, the secondary line is deactivated. The
secondary line waits 10 seconds after the primary goes down before activating,
and remains active for 60 seconds after the primary returns and becomes active
again.

7–22 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing

Configuring Dial-on-Demand Routing
Dial-on-demand routing (DDR) provides network connections in an environment
using the public switched telephone network (PSTN). Traditionally, networks
have been interconnected using dedicated lines for WAN connections. When
used with modems, DDR provides low-volume, periodic network connections
over a PSTN. This section details the commands required to interconnect the
DECbrouter 90 and the PSTN using data communications equipment (DCE)
devices and dial-on-demand routing.

DECbrouter 90 DDR Implementation
DDR allows attachment to modems that support V.25bis dialing. V.25bis is a
CCITT recommendation for initiating calls using an automatic calling unit (ACU).
V.25bis is useful for establishing calls when transmitting synchronous data.
DDR supports large internetworks with many routers through its support of
public circuit-switched networks such as telephone lines or switched services
provided by the telephone companies.
The V.25bis specification describes two modes of establishing or receiving
calls: the direct call mode and the addressed call mode. The DECbrouter 90
supports connections using the addressed call mode and synchronous, bitoriented operation. The addressed call mode allows the use of control signals
and commands sent over the DCE data interface to establish and terminate calls.
These commands are packaged in synchronous data frames (HDLC type) and are
sent when the interface is not in use for data transfer (that is, when a call does
not exist on the line).
The DECbrouter 90 supports connections from synchronous serial interfaces on
the router to any DCE device that supports V.25bis. Typically, these devices are
V.32 (9.6 kbps) or V.32 bis modems (14.4 kbps).
The DDR call-initiating process is driven by certain characteristics of bridged or
IP-routed packets. A router activates the dial-on-demand feature when it receives
a bridged or routed IP packet destined for a location on the other side of the
dial-up line. After the router dials the destination phone number and establishes
the connection, packets of any protocol that the DECbrouter 90 supports can
be transmitted. When the transmission is complete, the line is automatically
disconnected.
In order for the router to use a device for dialing out, in addition to V.25 bis, the
device must support certain hardware signals. When the router drops DTR, the
device must disconnect any calls that are currently connected. When the device
connects to the remote side, the device must have DCD become active.
Note
For many V.25bis devices, the requirement for DCD to be raised in
turn requires a special cable to swap DCD and DSRs, because the
V.25bis specification requires that DSR be raised when a connection is
established.

IS-IS, BGP, and OSPF cannot be used as routing protocols with DDR. This is
because they require an acknowledgment for routing updates, and DDR does not
necessarily establish a connection when a routing update is to be transmitted.

Configuring the Interfaces 7–23

Configuring the Interfaces
Configuring Dial-on-Demand Routing
For bridged traffic, packets of interest are based on packet type as specified
with the hexadecimal value in a bridge access list. Refer to the DECbrouter
90 Products, Configuration and Reference, Volume 3, Appendix B, for more
information about bridge access lists.
For IP traffic, packets of interest are based on the destination address; with a
routed IP packet, the destination address used is the next hop address. Packets
of interest are defined with IP access lists. Refer to the DECbrouter 90 Products,
Configuration and Reference, Volume 2 for more information concerning IP access
lists. Figure 7–1 illustrates a typical interconnection featuring dial-on-demand
routing.
Figure 7–1 Dial-on-Demand Interconnection

Ethernet

Public
Telephone
Network

DECbrouter 90

DECbrouter 90
DCE
Device
S1039a

DCE
Device

Specifying Dialer Type
Use the DIALER IN-BAND interface subcommand to specify that dial-on-demand
routing is to be supported on a synchronous serial line. The syntax for this
command is as follows:
dialer in-band
no dialer in-band
This command specifies that V.25bis dialing is to be used on the specified
interface. It is used only with serial interfaces.
Note
If an interface is going to only accept calls and never place them, the
DIALER IN-BAND interface subcommand is the only command needed to
configure it. If an interface is configured in this manner, with no dialer
groups (described in the next section), then it is always active, and the
idle timer never disconnects the line. It is up to the remote end (the end
that placed the call) to disconnect the line based on idle time.
The NO DIALER IN-BAND command disables dial-on-demand routing for the
interface.

7–24 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Example
The following example specifies dial-on-demand routing for serial 0:
interface serial 0
dialer in-band
When dialer in-band is specified, CRN is added to the front of the strings that
are sent to the V.25bis DCE. CRN is a V.25bis command that specifies that the
string that follows is a number to be called. This number is specified using the
DIALER STRING or DIALER MAP commands described later in this chapter.

Controlling Dialer Idle Time
Use the optional DIALER IDLE-TIMEOUT interface subcommand to specify
the idle time before the line is disconnected. The syntax for this command is as
follows:
dialer idle-timeout number-of-seconds
no dialer idle-timeout
The argument number-of-seconds specifies in seconds how much idle time must
occur on an interface before the line is disconnected. Acceptable values are
positive, nonzero integers. If no value is entered, the default is 120 seconds.
The NO DIALER IDLE-TIMEOUT command resets the idle timeout to the
default.

Example
The following example specifies of an idle timeout of 3 minutes (180 seconds) on
interface serial 1:
interface serial 1
dialer idle-timeout 180

Setting Idle Time for Busy Interfaces
Use the optional dialer FAST-IDLE interface subcommand to specify the idle time
before the line is disconnected for interfaces for which there is an unusually high
level of contention. The syntax for this command is as follows:
dialer fast-idle number-of-seconds
no dialer fast-idle
The argument number-of-seconds specifies in seconds how much idle time must
occur on an interface before the line is disconnected. Acceptable values are
positive, nonzero integers. If no value is entered, the default is 20 seconds.
This timer is used when an interface is connected and a packet is received
for a different destination (phone number). If the duration specified for the
DIALER FAST-IDLE command is exceeded and no traffic has been detected on
the connection during the fast idle period, the link is disconnected. This makes
the port available for making connections to an alternate destination (after the
dialer enable-timeout period expires) and reduces idle time on an interface.
This command only applies if multiple destinations have been specified for a
given interface using the DIALER MAP interface subcommand.
The no dialer fast-idle resets the timeout period to the default.
Configuring the Interfaces 7–25

Configuring the Interfaces
Configuring Dial-on-Demand Routing

Example
The following example specifies a fast idle timeout of 35 seconds on interface
serial 1:
interface serial 1
dialer fast-idle 35

Specifying Dialer Enable Time
Use the optional DIALER ENABLE-TIMEOUT interface subcommand to set the
length of time an interface stays down before it is available to dial again. The
command syntax is as follows:
dialer enable-timeout number-of-seconds
no dialer enable-timeout
Acceptable values for number-of-seconds are positive, nonzero integers. If no
value is entered, the default is 15 seconds. When a call terminates (hangs up or
is busy) this is the amount of time that the router waits before the next call can
occur on the specific interface.
The NO DIALER ENABLE-TIMEOUT command resets the enable timeout value
to the default.

Example
The following example specifies a waiting period of 30 seconds on interface serial
1:
interface serial 1
dialer enable-timeout 30

Specifying Carrier Wait Time
Use the optional DIALER WAIT-FOR-CARRIER-TIME interface subcommand to
specify how long to wait for a carrier. The command syntax is as follows:
dialer wait-for-carrier-time number-of-seconds
no dialer wait-for-carrier-time
The argument number-of-seconds specifies in seconds how long to wait for a
carrier to come up when a call is placed. Acceptable values are positive, nonzero
integers. If no value is entered, the default is 30 seconds. If a carrier signal is
not detected in this amount of time, the interface is disabled until the enable
timeout occurs.
The wait-for-carrier time is set to a default of 30 seconds, because this is the
estimated time required to make a typical connection over telephone lines.
The NO DIALER WAIT-FOR-CARRIER-TIME command resets the carrier wait
time value to the default.

7–26 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Example
The following example specifies a carrier wait time of 45 seconds on interface
serial 1:
interface serial 1
dialer wait-for-carrier-timeout 45

Specifying a Single DDR Telephone Number
Use the DIALER STRING interface subcommand to specify the string (telephone
number) to be called. The command syntax is:
dialer string dial-string
no dialer string
The argument dial-string specifies the character string to be called. Dialers
configured as in-band, pass the string to the external DCE. One DIALER
STRING command is specified per interface.
To specify multiple strings, use the DIALER MAP command, discussed next.
However, you must use the DIALER STRING command if you intend to bridge
traffic over the serial link or transmit broadcast traffic. In general, you include
a DIALER STRING or DIALER MAP command if you intend to use a specific
interface to initiate a dial-on-demand call.
Note
If a DIALER STRING command is specified for the interface, and no
DIALER-GROUP subcommand is assigned or no access lists are defined,
dialing never will be initiated. An error message will be displayed
indicating that dialing never will occur if DEBUG SERIAL-INTERFACE
is enabled.
The dial-string number specified in the DIALER STRING command is the default
number used under the following conditions:
•

A DIALER MAP command is not included in the interface configuration

•

The next-hop-address specified in a packet is not included in any of the
DIALER MAP interface subcommands recorded—assuming that the
destination address passes any access lists specified for dial-on-demand
through the DIALER-LIST command (discussed later in this section)

•

When bridging.

CCITT V.25bis Options
Depending on the type of modem you are using, CCITT V.25bis options are
supported as dial-string parameters of the DIALER STRING command. The
functions of the parameters are nation-specific, and they may have different
implementations in your country. These options apply only if you have enabled
DDR with the DIALER IN-BAND command. Refer to your manual for the modem
you are using for a list of supported options.

Configuring the Interfaces 7–27

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Table 7–4 CCITT V.25bis Options
Option

Description

wait tone

Pause
Usage and duration of this parameter vary by country.

Separator 3
For national use.

Separator 4
For national use.

Dialing to be continued in pulse mode.
Optionally accepted parameter.

Tone (Dialing to be continued in DTMF mode)
Optionally accepted parameter.

Flash
The flash duration varies by country.
Optionally accepted parameter.

The NO DIALER STRING command deletes the dialer string specified for the
interface.

Examples
The following example specifies a dial-on-demand telephone number on interface
serial 1 using the DIALER STRING command:
interface serial 1
dialer string 14085553434

Multiple Destinations
The DIALER STRING command is useful for environments in which a single
site is calling another site but the other site is not calling out. Often, however,
configurations are more complex, such as the hub-and-spoke environment shown
in Figure 7–2. In this configuration multiple sites are calling in to a central site,
and the central site is calling out to the remote sites.

7–28 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Figure 7–2 Hub-and-Spoke Environment Using Dial-on-Demand

Remote
Router E
Remote
Router D

Remote
Router A

Remote
Router C

Remote
Router B

S1159a

Central site

In this configuration, PPP with Challenge Handshake Authentication Protocol
(CHAP) authentication often is used to inform the central site about which
remote routers are connected to it. Using CHAP authentication, each remote
router identifies itself by a name, which informs the central router what routers
are currently connected to it. This identification process prevents the central
router from placing a call to a remote router if it is already connected to that
router.

Specifying Multiple Destinations
There are three forms of the interface subcommand you can use to define multiple
dial-on-demand numbers for a particular interface. They are as follows:
dialer map protocol next-hop-address username name
dialer map protocol next-hop-address dial-string
dialer map protocol next-hop-address username name dial-string
The first form of the dialer map command is used in central-site configurations in
which remote sites are calling a central site, but the central site is not calling the
remote site. With this command, the remote device will authenticate the central
site using CHAP, which will cause its name to be transmitted to the central site.
The central site will then use this name and the next-hop-address to correctly
transmit packets to the remote site. Because there is no dialer string specified,
the central site cannot call the remote router.
The second form of the command is used if only one site is being called.
The third form is used if many remote sites are calling the central site and the
central site also can call the remote sites. With this format, the central router
can use the name to identify the remote routers after they authenticate and
also can use the dialer string to call the remote routers if they are not currently
connected.
The keyword username indicates a remote system that the local router
communicates with.

Configuring the Interfaces 7–29

Configuring the Interfaces
Configuring Dial-on-Demand Routing
The following arguments can be used with this command:
•

The argument protocol has only one option at this time: ip.

•

The argument next-hop-address specifies the IP address used to match against
addresses to which packets are destined.

•

The argument name is the name of the remote device (usually the host name).

•

The dial-string argument is the telephone number sent to the DCE dialing
device when it sees packets with the specified next-hop-address that match
the access lists defined.

Unlike the DIALER STRING command, multiple DIALER MAP commands can
be specified per interface.
The DIALER MAP command complements the DIALER STRING command. The
dial-string defined for the DIALER STRING command is considered the default
dialer string. If a packet does not match the protocol and the next-hop-address
defined in the DIALER MAP commands (but does pass an access list that requires
initiation of automatic dialing), the default dialer string is used. This is often the
case for broadcasts and is always the case for bridging.
The NO DIALER MAP command deletes a particular dialer map entry. To delete
the entry, include the complete configuration string (no dialer map (protocol
next-hop-address dial-string).
Note
If no DIALER STRING command is defined, and the next-hop address
included in a packet does not match any of the next-hop-address
specifications in the DIALER MAP command, dialing never will be
initiated. Then an error message will be displayed indicating that dialing
never will occur if DEBUG SERIAL-INTERFACE is enabled.

Examples
In the following examples, a remote site is calling a central site, but the central
site is not calling the remote site. The remote device will authenticate the
central site using CHAP, which will cause its name, YYY, to be transmitted to the
central site. The central site will then use this name and the next-hop-address,
131.108.2.5, to correctly transmit packets to the remote site. Because there is no
dialer string specified, the central site cannot call the remote router.
interface serial 1
dialer map ip 131.108.2.5 username YYY
The following example specifies a dial-on-demand telephone number on interface
serial 1 for a specific destination address using the DIALER MAP command:
interface serial 1
dialer map ip 131.108.2.5 14155553434

7–30 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing
The remote site is calling the central site, and the central site is calling the
remote site. The central router can use the name, ZZZ, to identify the remote
router after they authenticate and also can use the dialer string 1415555343 to
call the remote router if it is not currently connected.
interface serial 1
dialer map ip 131.108.2.5 username ZZZ 1415555343

Dialer Rotary Groups
Dialer rotary groups allow you to apply a single interface configuration to a set of
interfaces. Once the interface configuration is propagated to a set of interfaces,
those interfaces can then be used to place calls using the standard dial-ondemand criteria. When many destinations are configured, any of these interfaces
can be used for outgoing calls.
Dialer rotary groups are useful in environments that require many calling
destinations. Only the rotary group needs to be configured with all of the
DIALER MAP commands. The only configuration required for the interfaces is
the DIALER ROTARY-GROUP command indicating that each interface is part of
a dialer rotary group.
Although a dialer rotary group is configured as an interface, it is not a physical
interface. Instead it represents a group of interfaces. Any number of dialer
groups can be defined.
Use the following interface command to designate a dialer rotary group leader:
interface dialer n

The argument n is any number and indicates a dialer group.
Interface subcommands entered after the INTERFACE DIALER command will be
applied to all physical interfaces assigned to rotary group n.

Example
This example identifies interface dialer 1 as the dialer rotary group leader.
Interface dialer 1 is not a physical interface, but represents a group of interfaces.
The interface subcommands that follow apply to all interfaces included in this
group. See the DIALER ROTARY-GROUP command, defined next.
interface dialer 1
encapsulation ppp
dialer in-band
dialer map ip 131.108.2.5 username YYY 1415553434
dialer map ip 131.126.4.5 username ZZZ
Use the following interface subcommand to include an interface in a dialer rotary
group:
dialer rotary-group n
The argument n is the number of the rotary group (defined by the interface dialer
command).

Configuring the Interfaces 7–31

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Example
The following configuration places serial interfaces 0 and 1 into dialer rotary
group 1, defined by the INFERFACE DAILER 1 command.
! PPP encapsulation is enabled for interface dialer 1.
interface dialer 1
encapsulation ppp
dialer in-band
! The first dialer map command allows remote site YYY and the
! central site to call each other. The second dialer map command, with no
! dialer string, allows remote site ZZZ to call the central site but
! the central site can not call remote site ZZZ (no phone number).
dialer map ip 131.108.2.5 username YYY 1415553434
dialer map ip 131.126.4.5 username ZZZ
! The DTR pulse signals for three seconds on the interfaces in dialer
! group 1. This holds the DTR low so the modem can recognize that DTR
has been
! dropped.
pulse-time 3
! Interfaces serial 0 and serial 1 are placed in dialer rotary group 1.
All of
! the interface subcommands (the encapsulation and dialer map commands shown
! earlier in this example)applied to interface dialer 1 apply
! to these interfaces.
interface serial 0
dialer rotary-group 1
interface serial 1
dialer rotary-group 1

Assigning Access Lists to a DDR Interface
Use the DIALER-GROUP interface subcommand to assign an interface to a set of
access list expressions. These access list expressions define which packets cause a
connection to be established and which packets keep an interface from being idle.
The syntax for this command is as follows:
dialer-group group-number
no dialer-group
The argument group-number specifies the number of the dialer group to which
the specific interface belongs. Acceptable values are nonzero, positive integers.
This group number corresponds to a dialer group defined using the DIALER-LIST
command (described in the next section).
An interface only can be associated with a single dialer group; multiple DIALERGROUP assignment is not allowed.
The NO DIALER-GROUP command removes an interface from the specified
dialer group.

7–32 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Example
The following example specifies dialer group number 1. This dialer group number
will be compared against any global DIALER-LIST specifications. If there is
a group number match, the destination address of the packet in question is
evaluated against the access list specified in the associated DIALER-LIST
command. If it passes, a call is initiated or the idle timer is reset (if a call is
currently connected).
interface serial 1
dialer-group 1

Using Access Lists with DDR
Control automatic dialing using DDR with the following combination: standard
IP or bridging access lists; the DIALER-LIST global command; and the DIALERGROUP interface subcommand (described in the preceding section). Refer
to the DECbrouter 90 Products, Configuration and Reference, Volume 2 and
the DECbrouter 90 Products, Configuration and Reference, Volume 3 for more
information about access lists. The DIALER-LIST global configuration command
has two forms. They have the following syntaxes:
dialer-list dialer-group-number list list-number
no dialer-list dialer-group-number list list-number
dialer-list dialer-group protocol protocol-name {permit | deny}
no dialer-list dialer-group protocol protocol-name {permit | deny}

Note
The permit/deny version of the DIALER-LIST command provides a very
coarse method of allowing or denying protocols that prevent a link from
being considered idle or from causing dialing. In most cases, this form of
the DIALER-LIST command is not recommended because most network
protocols have periodic messages. These periodic messages cause the
interface to remain active; thus, the line is never disconnected. Currently,
filtering using access lists is only provided for routing IP and bridging. In
addition, only those access lists applicable to bridging and IP routing are
supported by the dial-on-demand facilities.
The argument dialer-group-number specifies the number of a dialer group
identified in any DIALER GROUP interface subcommand.
The argument list-number is the access list number specified in any IP or bridging
access list.

Configuring the Interfaces 7–33

Configuring the Interfaces
Configuring Dial-on-Demand Routing
The argument protocol-name is one of the following supported protocols:
•

ip—IP

•

decnet—DECnet

•

chaos—CHAOSnet

•

xns—XNS

•

novell—Novell IPX

•

appletalk—AppleTalk

•

vines—Banyan Vines

•

apollo—Apollo Domain

•

pup—PUP

•

clns—OSI Connectionless Network Service

•

bridge—Bridging

•

stun—Serial tunneling

•

cmns—OSI Connection-Mode Network Services
Note
Access lists are central to the operation of dial-on-demand routing for the
DECbrouter 90. In general, they are used as the screening criteria for
determining when to initiate DDR calls. When an access list is found to
match with the packet being tested, the idle timer is reset or a connection
is attempted (assuming the line is not active, but is available). If a
tested packet is deemed uninteresting (it does not match any access list
specifications), it will be forwarded if it is intended for a destination
known to be on a specific interface and the link is active. However, such a
packet will not initiate a DDR call and will not reset the idle timer.

Example
Dialing occurs when an interesting packet (one that matches access list
specifications) needs to be output on an interface. Using the standard access list
method, packets can be classified as interesting or uninteresting. For example,
to specify that IGRP updates are not interesting (relative to dial-on-demand
automatic dialing), the following access list would be defined:
access-list 101 deny igrp 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.0
To permit all other IP traffic, the above would be followed by:
access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255
Then, the following command would be used to place list 101 into dialer group 1:
dialer-list 1 list 101

7–34 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Dial-on-Demand Access-List Configuration Examples
The examples provided in this section illustrate various DDR configurations using
access lists linked to DDR facilities provided with the router.

Example 1
The following example illustrates how dial-on-demand routing can be used in an
IP environment:
interface serial 0
ip address 131.108.126.1 255.255.255.0
dialer in-band
dialer idle-timeout 600
dialer string 555-1234
pulse-time 1
dialer-group 1
!
access-list 101 deny igrp 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.0
access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255
dialer-list 1 list 101
ip route 131.108.29.0 131.108.126.2
ip route 131.108.1.0 131.108.126.2
Configuration specifications in this example define the following characteristics:
•

DIALER IN-BAND command selects V.25bis dialing.

•

DIALER IDLE-TIMEOUT 600 command sets the dialer idle timeout to 10
minutes (600 seconds).

•

DIALER STRING 555-1234 command sets the phone number to be called to
555-1234.

•

PULSE-TIME 1 command sets the DTR pulse time to be one second. This
is to give the modem enough time to recognize that DTR has dropped so the
modem will disconnect the call.
Note
With many modems, the PULSE-TIME command must be used so that
DTR is dropped for sufficient time to allow the modem to disconnect.

•

dialer-group 1 adds this interface to the dialer group defined with the
dialer-list command.

•

The first access list statement used specifies that IGRP updates to any
address will not cause dialing. However, if a connection is already
established, IGRP updates will be transmitted but will not reset the idle
timers.

•

The second access-list statement specifies that all other IP traffic—such as
Ping, Telnet, or any other IP packet—will cause dialing.

•

The DIALER-LIST command then creates dialer group 1 and states that
access list 101 is to be used to match for automatic dialing.

•

The IP ROUTE commands specify that there is a route to network
131.108.29.0 and to network 131.108.1.0 through 131.108.126.2. This means
that several destination networks are available through the serial port.

Configuring the Interfaces 7–35

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Note
The REDISTRIBUTE STATIC command can be used to advertise
static route information for dial-on-demand applications. See the
REDISTRIBUTE STATIC command, described in DECbrouter 90
Products, Configuration and Reference, Volume 2, Chapter 6, "IP
Routing Protocols." This command is useful for environments in which
a workstation is connecting to a site that is reachable by DDR across
multiple routers. Without this command, static routes must be defined for
each route between your workstation and the DDR router.

Example 2
The following example illustrates a configuration for bridging:
interface serial 0
ip address 131.108.126.10 255.255.255.0
dialer in-band
dialer string 555-1234
pulse-time 1
bridge-group 1
dialer-group 1
!
!
bridge 1 protocol dec
access-list 201 deny 0x6002 0x0000
access-list 201 deny 0x6003 0x0000
access-list 201 permit 0x0000 0xFFFF
dialer-list 1 LIST 201
As in Example 1, the dialer is set to use V.25bis, the dialer string is specified,
and a pulse time is assigned. This interface is then added to bridge group 1 and
dialer group 1.
The access lists work as follows:
•

The first one states that Digital MOP packets are not to cause dialing.

•

The second states that DECnet Phase IV should not cause dialing.

•

The last states that all other bridged packets should cause dialing.

This example could be used in a case where LAT is the only traffic to be
transmitted over the link.
Note
Spanning-tree updates and HDLC keepalives implicitly do not cause
dialing and do not reset the idle timers.

7–36 Configuring the Interfaces

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Example 3
The following example is a combination of Examples 1 and 2. It illustrates how
to handle DDR for bridging and IP routing over a single interface.
The first access-list statement specifies that RIP updates to the broadcast
address do not cause dialing. However, if a connection is already established, RIP
updates are transmitted, although they do not reset the idle timers and do not
keep the line up.
interface serial 0
ip address 131.108.126.10 255.255.255.0
dialer in-band
dialer string 555-1234
pulse-time 1
bridge-group 1
dialer-group 1
!
!
bridge 1 protocol dec
access-list 101 deny udp 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.0
eq 520
access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255
access-list 201 deny 0x6002 0x0000
access-list 201 deny 0x6003 0x0000
access-list 201 permit 0x0000 0xFFFF
dialer-list 1 LIST 101
dialer-list 1 LIST 201

Example 4
The following example demonstrates how to specify multiple destination dial
strings (phone numbers):
interface serial 0
ip address 131.108.126.1 255.255.255.0
dialer in-band
dialer wait-for-carrier-time 40
dialer string 555-1234
pulse-time 1
dialer-group 1
dialer map ip 131.108.126.10 555-8899
dialer map ip 131.108.127.1 555-5555
!
access-list 101 deny igrp 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.0
access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255
dialer-list 1 LIST 101
As in Example 1, the serial interface is configured for V.25bis. It also is set to
have a wait-for-carrier-time of 40 seconds. As before, a default dial string is
configured, a pulse time assigned, and a dialer group specified.
The first DIALER MAP command specifies that the number 555-8899 is to be
dialed for IP packets with a next-hop-address of 131.108.126.10. The second
dialer map then specifies that the number 555-5555 will be called when an IP
packet with a next-hop-address of 131.108.127.1 is detected.
Access lists for this example match those defined in Example 1.

Configuring the Interfaces 7–37

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Example 5
The following example illustrates using floating static routes (see DECbrouter
90 Products, Configuration and Reference, Volume 2, Chapter 6, "The IP Routing
Protocols") and dial-on-demand to perform the same functionality as dial backup,
except using V.25bis for dialing.
interface serial 0
ip address 131.108.126.1 255.255.255.0
dialer in-band
dialer wait-for-carrier-time 10
dialer string 555-1234
pulse-time 1
dialer-group 1
dialer map ip 131.108.126.10 555-8899
dialer map ip 131.108.127.1 555-5555
!
access-list 101 deny igrp 0.0.0.0 255.255.255.255 255.255.255.255 0.0.0.0
access-list 101 permit ip 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255
dialer-list 1 LIST 101
ip route 131.108.42.0 131.108.126.10 150
The configuration is essentially the same as in Example 4, except for the addition
of an IP ROUTE statement. This statement specifies that to reach network
131.108.42.0 through this router, traffic must use 131.108.126.10 as the gateway.
This causes dialing to occur to 555-8899.
Because the IP ROUTE statement specifies an administrative distance (150),
dynamic routing information will override the static route—no packets will
normally be sent to 131.108.126.10. However, if the route that is learned
dynamically disappears, and no other dynamic route is available, the static
route will be used and dialing will occur. See the DECbrouter 90 Products,
Configuration and Reference, Volume 2, Chapter 6, "The IP Routing Protocols" for
more information on static routes.

Monitoring Dial-on-Demand Routing
To obtain a general diagnostic display for serial interfaces configured for dial-ondemand routing, use the SHOW DIALER EXEC command. The command syntax
is as follows:
show dialer [interface interface type]
This command displays information about the dialer interfaces. If SHOW
DIALER is specified, all dialers are displayed. An interface can be specified
using the SHOW DIALER INTERFACE option. The arguments interface and type
specify the particular interface, and can be formed either as a two-part identifier
(such as serial 0, ser 1, s 2, and so on) or as a name (serial1).
The following is a sample of output from the SHOW DIALER command with a
serial interface:
Serial 0 - dialer type = IN-BAND
Idle timer (600 secs), Fast idle timer (20 secs)
Wait for carrier (30 secs), Re-enable (15 secs)
Dial String
Successes Failures
Last called
8985
0
2
0:24:10
8986
1
0
1:20:07

7–38 Configuring the Interfaces

Last status
Failed
Default
Successful

Configuring the Interfaces
Configuring Dial-on-Demand Routing
The following information is provided in this display:
•

"IN-BAND" specification indicating that DDR is enabled

•

Idle timeout specification (seconds)

•

Fast-idle timer specification (seconds)

•

Wait-for-carrier timer specification (seconds)

•

Enable timeout specification (seconds)

•

Dial strings of logged calls (telephone numbers)

•

Successful connections (even if no data is passed)

•

Failed connections—line busy when call attempted

•

Time that last call occurred to specific dial string

•

Last status of calls to specific dial string (successful or failed)

•

If the DDR facility is using the dial string specified with the DIALER
STRING command, the word Default is appended to the Last status entry

If the dialer is connected to another dialer (and the system from which the SHOW
DIALER command was entered was the initiator of the call), a display is provided
that indicates the idle time before the line is disconnected (decrements each
second) and the duration of the current connection. The following is a sample of
this display; it would appear after the third line in the SHOW DIALER display:
Time until disconnect 596 secs
Current call connected 0:00:25
After a call disconnects, the system displays the time remaining before being
available to dial again. The following is a sample of this display; it would appear
after the third line in the SHOW DIALER display.
Time until interface enabled 8 secs
If the SHOW DIALER interface command is issued for an interface on which
DDR is not enabled, the system displays an error message. The following is a
sample error message:
Serial 1 - Dialing not enabled on this interface.
If an interface is configured for DDR, the SHOW INTERFACES command now
displays the following:
Serial 0 is up, line protocol is up (spoofing)
Hardware is MK5025
The spoofing indicates that the line really is not up, but the dialer is forcing the
line to masquerade as "up" so that upper-level protocols will continue to operate
as expected.

Configuring the Interfaces 7–39

Configuring the Interfaces
Configuring Dial-on-Demand Routing
Debugging Dial-on-Demand Routing
When DDR is configured for a serial interface, the EXEC commands DEBUG
SERIAL-INTERFACE (described earlier in this chapter) and DEBUG SERIALPACKET can provide information associated with DDR activity, as follows:
debug serial-interface
This command enables monitoring of serial interface activity. For DDR, the
following information may appear:
•

A message indicating that a call is being attempted

•

A message stating that no dialer group has been defined and dialing will not
occur

•

Messages indicating that idle timeouts, reenable timeouts, and wait-forcarrier timeouts have occurred

•

A message from the DCE device indicating the dial string attempted

The DEBUG SERIAL-PACKET command enables monitoring of serial packets.
debug serial-packet
When activated, and DDR is enabled on the interface, information concerning
the cause of any calls (called Dialing cause) may be displayed. The cause for IP
packets lists the source and destination addresses; the cause for bridged packets
lists the type of packet in hexadecimal.

Configuring the Point-to-Point Protocol
The point-to-point protocol (PPP), described in RFC 1134, is designed to
encapsulate internet protocol (IP) datagrams and other network layer protocol
information over point-to-point links. The document "Point-to-Point Initial
Configuration Options" defines the set of options that are negotiated during
startup.
The current implementation of PPP supports no configuration options. The
software sends no options, and any proposed options are rejected.
Of the possible upper-layer protocols, only IP is supported at this time. Thus, the
only upper-level protocol that can be sent or received over a point-to-point link
using PPP encapsulation is IP. Refer to RFC 1134 for definitions of the codes and
protocol states.
The PPP is enabled on an interface using the ENCAPSULATION interface
subcommand followed by the ppp keyword.
encapsulation ppp

Example
These commands enable PPP encapsulation on serial interface 0 (zero):
interface serial 0
encapsulation ppp

7–40 Configuring the Interfaces

Configuring the Interfaces
Configuring the Point-to-Point Protocol
Challenge Handshake Access Protocol (CHAP)
Access control using CHAP is available on all serial interfaces. The
authentication feature reduces the risk of security violations on your router.
CHAP is only supported on lines using PPP encapsulation.
When CHAP is enabled, a remote device (a PC, workstation, router, or
communication server) attempting to connect to the local communication server
is requested, or "challenged," to respond. The required response is an encrypted
version of a secret password, or "secret," plus a random value and the name of
the remote device. This name must be configured as described in the Configuring
Host Name Authentication section later in this chapter.
By transmitting this response, the secret is never transmitted, preventing other
devices from stealing it and gaining illegal access to the system. Without the
proper response, the remote device cannot connect to the local router.
CHAP transactions occur only at the time a link is established. The local router
does not request a password during the rest of the call. (The local router can,
however, respond to such requests from other devices during a call.)
The DECbrouter 90 implementation of CHAP does not support the callback
option. (The callback option requires that the called router hang up and return
the call to a preconfigured telephone number.)
To use CHAP, you must perform the following steps. (These steps are described
later in this section.)
1. Enable CHAP on the interface.
2. Configure server authentication.

Note
To use CHAP, you must be running PPP encapsulation.
CHAP is specified in the IETF draft "The PPP Authentication Protocols" by Brian
Lloyd of Lloyd and Associates and William A. Simpson of Computer Systems
Consulting Services. The latest version is dated December 1991.
CHAP is specified as an additional authentication phase of the PPP link control
protocol.

Enabling CHAP on the Interface
To enable CHAP on the interface, use this interface command:
ppp authentication chap
Once you have enabled CHAP, the local router requires a password from remote
devices. If the remote device does not support CHAP, no traffic will be passed to
that device.

Configuring the Interfaces 7–41

Configuring the Interfaces
Configuring the Point-to-Point Protocol
Configuring Host Name Authentication
Configure the secret using the following command:
username name password secret
Add a username entry for each remote system that the local router communicates
with and requires authentication from.
The name argument is the host name of either the local router or a remote device.
Note
To enable the local router to respond to remote CHAP challenges, one
username name entry must be the same as the hostname name that
has already been assigned to your router. See Setting the Host Name in
Chapter 4.
The secret argument specifies the secret for the local router or the remote device.
If there is no secret specified, and DEBUG SERIAL-INTERFACE is enabled,
an error is displayed when a link is established, and the CHAP challenge
is not implemented. Debugging information on CHAP is available using the
DEBUG SERIAL-INTERFACE and DEBUG SERIAL-PACKET commands. See
the Interface Support EXEC Command Summary for a description of these
debugging commands.
The secret is encrypted when it is stored on the local router. This prevents it from
being stolen. It can consist of any string of up to 11 printable ASCII characters.
There is no limit to the number of username/password combinations that can be
specified, allowing any number of remote devices to be authenticated using CHAP.

Example
The following example configuration enables CHAP on interface serial 0. It also
defines a password for the local server, " "XXX" and a remote server, "YYY."
hostname XXX
interface serial 0
encapsulation ppp
ppp authentication chap
username XXX password oursystem
username YYY password theirsystem
When you look at your configuration file, the passwords will be encrypted and the
display will look something like the following:
hostname XXX
interface serial 0
encapsulation ppp
ppp authentication chap
username XXX password 7 1514040356
username YYY password 7 121F0A18

7–42 Configuring the Interfaces

Configuring the Interfaces
Configuring the Point-to-Point Protocol
Example:Dial-on-Demand PPP Configuration
The following example shows a configuration in which several aspects of DDR are
used to provide DDR capabilities between local and remote routers. The following
features are shown in this example.
•

DIALER MAP command

•

PPP encapsulation

•

CHAP

•

Dialer rotary groups

•

PULSE-TIME command (See Chapter 8 for a description of this command.)

! Enable PPP encapsulation and CHAP on interface dialer 1.
interface dialer 1
encapsulation ppp
ppp authentication chap
! Specify dial-on-demand routing supported on a synchronous serial line and
! assign a set of access-list expressions.
dialer in-band
dialer group 1
! The first dialer map command indicates that calls between the remote site
! YYY and the central site will be placed at either end. The second dialer
! map command, with no dialer string, indicates that remote
site ZZZ will call
! the central site but the central site will not call out.
dialer map ip 131.108.2.5 username YYY 1415553434
dialer map ip 131.126.4.5 username ZZZ
! The DTR pulse holds the DTR low for three seconds, so the
modem can recognize
! that DTR has been dropped.
pulse-time 3
! Place serial interfaces 0 and 1 in dialer rotary group 1. The
! interface subcommands applied to dialer rotary group 1 (for example,
! PPP encapsulation and CHAP) apply to these interfaces.
interface serial 0
dialer rotary-group 1
interface serial 1
dialer rotary-group 1
! CHAP passwords are specified for local and remote servers.
username XXX password oursystem
username YYY password theirsystem
username ZZZ password thatsystem
Figure 7–3 shows a configuration in which remote routers YYY and ZZZ and
local router XXX are using dial-on-demand routing, as configured in the previous
example. In this configuration, remote routers YYY and ZZZ can call router XXX.
Router XXX has dialer string information only for router YYY and cannot call
router ZZZ.

Configuring the Interfaces 7–43

Configuring the Interfaces
Configuring the Point-to-Point Protocol
Figure 7–3 Dial-on-Demand Routing Configuration

Public Switched
Telephone Network
(PSTN)

Local site
XXX

Call fro

m ZZZ

to XXX

only

Remote
site YYY
131.108.2.5
1415553434

Remote
site ZZZ

S1200a

XX to YYY
Calls from X
Y to XXX
Y
Y
and from

131.126.4.5

Configuring the Null Interface
Support is provided for a null interface. This pseudo-interface functions similarly
to the null devices available on most operating systems. This interface is always
up and can never forward or receive traffic; encapsulation always fails.
The null interface provides an alternative method of filtering traffic. The
overhead involved with using access lists can be avoided by directing undesired
network traffic to the null interface.
To specify the null interface, specify null 0 (or null0) as the interface name and
unit. The null interface can be used in any command that has an interface type
as a parameter.

Example
This command configures a null interface for IP route 127.0.0.0:
ip route 127.0.0.0 null 0

Global Configuration Command Summary
The following summary lists the global configuration commands used for interface
support.
[no] dialer-list dialer-group list list-number
[no] dialer-list dialer-group protocol protocol-name {permit | deny}
Controls automatic dialing using DDR using standard IP or bridging access
lists.
The argument dialer-group specifies the number of a dialer group identified in
any DIALER-GROUP interface subcommand.
The argument list-number is the access list number specified in any IP or
bridging access list.
The argument protocol-name is one of the following supported protocols:
•

ip—IP

•

decnet—DECnet

7–44 Configuring the Interfaces

Configuring the Interfaces
Global Configuration Command Summary
•

chaos—CHAOSnet

•

xns—XNS

•

novell—Novell IPX

•

appletalk—AppleTalk

•

vines—Vines

•

apollo—Apollo Domain

•

pup—PUP

•

clns—OSI Connectionless Network Service

•

bridge—Bridging

•

stun—Serial tunneling

•

cmns—OSI Connection-Mode Network Service

interface type unit
Specifies an interface. The argument type specifies the interface type—
ethernet or serial—and the argument unit specifies the interface number.

Interface Support Subcommand Summary
Following are alphabetically arranged summaries of the interface subcommands
for interface support.
[no] backup delay {enable-delay | never} {disable-delay | never}
Defines how much time should elapse before a line is set up or taken down.
The argument enable-delay is the delay in seconds after the primary line goes
down before the secondary line is activated. The argument disable-delay is
the delay in seconds after the primary line goes up before the secondary line
is deactivated. The never keyword prevents the secondary line from being
activated due to a primary line failure. The no version disables the specified
delay time.
[no] backup interface interface-name
Configures the serial interface as a secondary, or dial backup, line. The
argument interface-name specifies the serial port to be set as the secondary
interface line. Use the NO BACKUP interface command with the appropriate
serial port designation to turn this feature off.

Configuring the Interfaces 7–45

Configuring the Interfaces
Interface Support Subcommand Summary
[no] backup load {enable-threshold | never} {disable-load | never}
Sets the traffic load thresholds. The arguments enable-threshold and disableload are percentage numbers representing the load as a percentage of
the primary line’s available bandwidth. The never keyword prevents the
secondary line from being activated due to load. By default, no backup loads
are defined; the no form of the command restores this default.
[no] description name-string
Adds a descriptive name to an interface. The argument name-string is
a comment to be put in the configuration. The no version removes the
name-string.
[no] dialer enable-timeout number-of-seconds
Sets how long an interface stays down before it is available to dial again.
Acceptable values are positive, nonzero integers. If no value is entered, the
default is 15 seconds.The NO DIALER ENABLE-TIMEOUT command resets
the enable timeout value to the default.

[no] dialer fast-idle number-of-seconds
Specifies the idle time before the line is disconnected for interfaces for which
there is an unusually high level of contention. Acceptable values are positive,
nonzero integers. If no value is entered, the default is 20 seconds. This timer
is used when an interface is connected and a packet is received for a different
destination. This command only applies if multiple destinations have been
specified for a given interface using the DIAL MAP interface subcommand.
The NO DIALER FAST-IDLE resets the timeout period to the default.
[no] dialer-group group-number
Assigns an interface to a set of access list expressions. These access list
expressions define what packets cause a connection to be established and
what packets keep an interface from being idle.
The argument group-number specifies the number of the dialer group to
which the specific interface belongs. Acceptable values are nonzero, positive
integers. This group number corresponds to a dialer group defined using the
DIALER-LIST command (described below).
An interface can only be associated with a single dialer-group.
The NO DIALER-GROUP command removes an interface from the specified
dialer-group.

7–46 Configuring the Interfaces

Configuring the Interfaces
Interface Support Subcommand Summary
[no] dialer idle-timeout number-of-seconds
Specifies the idle time before the line is disconnected.
The argument number-of-seconds specifies in seconds how much idle time
must occur on an interface before the line is disconnected. Acceptable values
are positive, nonzero integers. If no value is entered, the default is 120
seconds.
The NO DIALER IDLE-TIMEOUT command resets the idle timeout to the
default.
[no] dialer in-band
Specifies that V.25bis dialing is to be used on the specified interface. This is
only used with serial interfaces.
The NO DIALER IN-BAND command disables dial-on-demand routing for the
interface.
dialer map protocol next-hop-address username name
dialer map protocol next-hop-address dial-string
dialer map protocol next-hop-address username name dial-string
Three forms of the interface subcommand can be used to define multiple
dial-on-demand numbers for a particular interface. The first form of the
dialer map command is used in central-site configurations in which remote
sites are calling a central site, but the central site is not calling the remote
site. The second form of the command is used if only one site is being called.
The third form is used if many remote sites are calling the central site and
the central site also can call the remote sites.
The keyword username indicates a remote system that the local router
communicates with.
The following arguments can be used with this command:
•

The argument protocol has only one option at this time: ip.

•

The argument next-hop-address specifies the IP address used to match
against addresses to which packets are destined.

•

The argument name is the name of the remote device.

•

The dial-string argument is the telephone number sent to the DCE dialing
device when it sees packets with the specified next-hop-address that match
the access lists defined.
The NO DIALER MAP command deletes a particular dialer map entry.

Configuring the Interfaces 7–47

Configuring the Interfaces
Interface Support Subcommand Summary
dialer rotary-group n
Includes an interface in a dialer rotary group. The argument n is the number
of the rotary group (defined by the INTERFACE DIALER command).
[no] dialer string dial-string
Specifies the string (i.e., telephone number) to be passed to the DCE device
(typically a V.25bis modem).
The argument dial-string specifies the character string to be passed to the
V.25bis DCE device. The DECbrouter 90 places the V.25bis command CRN in
front of the specified string. One DIALER STRING command is specified per
interface.
The NO DIALER STRING command deletes the dialer string specified for the
interface.
[no] dialer wait-for-carrier-time number-of-seconds
Specifies how long to wait for the carrier to come up when a call is placed.
Acceptable values are positive, nonzero integers. If no value is entered, the
default is 30 seconds. If a carrier signal is not detected in this amount of
time, the interface is disabled until the enable timeout occurs.
The wait-for-carrier time is set to a default of 30 seconds since this is the
estimated time required to make a typical connection of telephone lines.
The NO DIALER WAIT-FOR-CARRIER-TIME command resets the carrier
wait time value to the default.
encapsulation encapsulation-type
Assigns an encapsulation method. The encapsulation-type argument is a
keyword that identifies one of the following encapsulation types that the
software supports:
•

arpa—Ethernet Version 2.0 encapsulation

•

bfex25—Blacker front end encryption X.25 operation

•

ddnx25-dce—DDN X.25 DCE operation

•

ddnx25—DDN X.25 DTE operation

•

frame-relay—Frame relay

•

hdh—HDH protocol

•

hdlc—HDLC protocol

•

iso1—IEEE 802.3 encapsulation

•

lapb-dce—X.25 LAPB DCE operation

•

lapb—X.25 LAPB DTE operation

•

multi-lapb-dce—X.25 LAPB multiprotocol DCE operation

7–48 Configuring the Interfaces

Configuring the Interfaces
Interface Support Subcommand Summary
•

multi-lapb—X.25 LAPB multiprotocol DTE operation

•

ppp—Point-to-point protocol (PPP)

•

snap—IEEE 802.2 Ethernet media

•

smds—SMDS service

•

x25-dce—X.25 DCE operation

•

x25—X.25 DTE operation

ppp authentication chap
Enables CHAP on an interface. Once you have enabled CHAP, the local
router requires a password from remote devices. If the remote device does not
support CHAP, no traffic will be passed to that device.
[no] shutdown
Disables and enables an interface.
username name password secret
Adds a username entry for each remote system that the local router
communicates with and requires authentication from. The name argument
is the host name of either the local router or a remote device. The secret
argument specifies the secret for the local router or the remote device.

Interface Support EXEC Command Summary
Following is an alphabetically arranged summary of the EXEC interface support
commands.
clear counters [interface-name]
The argument interface-name is the name of the interface (examples are
serial 0, Ethernet 1, and so on).
clear interface [type unit]
Resets the hardware logic on an interface. Argument type is the specific
interface type keyword (ethernet or serial); the argument unit is the
interface number (0 or 1).

Configuring the Interfaces 7–49

Configuring the Interfaces
Interface Support EXEC Command Summary
[un]debug broadcast
Enables you to log all level 2 (MAC) broadcast packets received. This
information is useful for finding the source of a broadcast storm. Use the
undebug version of the command to stop debug messaging.
[un]debug packet
Enables logging of packets that the router is unable to classify. Examples of
this are packets with an unknown Ethernet link type, or IP packets with an
unrecognized protocol field.
[un]debug serial-interface
Enables or disables logging of serial interface events.
[un]debug serial-packet
Enables logging of serial interface events. Provides more detail than debug
serial-interface.
show dialer [interface interface type]
Displays information the dialer interfaces.
show interfaces [type unit] [accounting]
Displays statistics for the network interfaces on the DECbrouter 90. The
optional argument type can be one of the following: ethernet or serial.
The argument unit specifies the interface unit or card number. The optional
keyword accounting displays the number of packets of each protocol type
that have been sent through the interface.
show version
Displays the configuration of the system hardware, the software version, the
names and sources of configuration files, and the boot images.

7–50 Configuring the Interfaces

8
Adjusting Interface Characteristics
This chapter describes how to make adjustments to the router interfaces and how
to enable loopback tests. The tasks in this chapter include:
•

Switching and scheduling priorities

•

Priority output queuing

•

Interface hold queues

•

Setting the bandwidth

•

Setting delay

•

Setting loopback testing on an interface

To adjust or test an interface, you must be in the configuration command
collection mode. To enter this mode, enter the EXEC command CONFIGURE at
the EXEC prompt. Once in the command collection mode, start configuring the
interface by entering the INTERFACE command.
A summary of the interface subcommands described in this chapter is included at
the end of the chapter.

Adjusting Serial Interface Characteristics
The following sections describe adjustments that can be made to serial interfaces.

Specifying Transmit Delay
The DECbrouter 90 serial interface may send back-to-back data packets faster
than hosts can receive them. You can slow the interface card’s transmit rate
by using the transmitter-delay interface subcommand. The full syntax of the
command follows.
transmitter-delay hdlc-flags
no transmitter-delay
The argument hdlc-flags causes a minimum number of HDLC flags to be sent
between each packet. The valid range is 2 to 62; the default is 0.

Configuring DTR Signal Pulsing
The PULSE-TIME interface subcommand enables pulsing DTR signals on the
DECbrouter 90 serial interfaces. The full syntax of the command follows.
pulse-time seconds
no pulse-time
The argument seconds specifies the interval. When the serial line protocol goes
down (for example, because of loss of synchronization), the interface hardware is
reset and the DTR signal is held inactive for at least the specified interval. This
Adjusting Interface Characteristics 8–1

Adjusting Interface Characteristics
Adjusting Serial Interface Characteristics
function is useful for handling encrypting or other similar devices that use DTR
signal toggling to resynchronize.
This command also is used to specify the time allowed for a modem to recognize
that DTR has dropped so that the modem can disconnect the call.
The default interval is zero seconds, which is restored by the NO PULSE-TIME
command.

Example
This command enables DTR pulse signals for three seconds on interface serial 2.
interface serial 2
pulse-time 3

Adjusting Characteristics That Apply to All Interface Types
The following sections describe adjustments that apply to all interface types.

Configuring Switching and Scheduling Priorities
The normal operation of the DECbrouter 90 allows the switching operations to
use as much of the central processor as is required. If the network is running
unusually heavy loads that do not allow the processor the time to handle
the routing protocols, give priority to the system process scheduler using the
SCHEDULER-INTERVAL global configuration command. The full command
syntax follows.
scheduler-interval milliseconds
no scheduler-interval
The SCHEDULER-INTERVAL command controls the maximum amount of
time that can elapse without running the lowest-priority system processes.
The minimum interval that can be specified is 500 milliseconds; there is no
maximum value. The default is to allow high-priority operations to use as much
of the central processor as needed. The NO SCHEDULER-INTERVAL command
restores that default.

Example
This command changes the low-priority process schedule to an interval of 750
milliseconds.
scheduler-interval 750

Priority Output Queuing
Priority output queuing is a mechanism that allows the administrator to set
priorities on the type of traffic passing through the network. To do so, it
prioritizes the packets transmitted on an interface. Packets are classified
according to various criteria, including protocol and subprotocol type, and then
queued on one of four output queues.

8–2 Adjusting Interface Characteristics

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
When the DECbrouter 90 is ready to transmit a packet, it scans the priority
queues in order, from highest to lowest, to find the highest-priority packet. After
that packet is completely transmitted, the router scans the priority queues again.
If a priority output queue fills up, packets will be dropped and, for protocols such
as IP and CLNS, quench indications will be sent to the original transmitter.
Although priority queuing can be enabled for any interface, the intended
application was for low-bandwidth, congested serial interfaces.
The priority output queuing mechanism allows traffic control based on protocol
or interface type. Commands also are offered to set the size of the queue and
defaults for what happens to packets that are not defined by priority output
queue rules.
The priority output queuing mechanism can be used to manage traffic from all
networking protocols and from bridges. Additional fine-tuning is available for IP
and for setting boundaries on the packet size.
Note
Priority queuing introduces extra overhead that is acceptable for slow
interfaces but may not be acceptable for higher-speed interfaces such as
Ethernet. Also note that priority queuing does not operate over X.25.
There are four priority queues—high, medium, normal, and low—listed in order
from highest to lowest priority.
Keepalives sourced by the router always are assigned to the high-priority queue;
all other management traffic (such as IGRP updates) must be configured. Packets
that are not classified by the priority list mechanism are assigned to the normal
queue.
A priority list is a set of rules that describes how packets should be assigned to
priority queues. A priority list also can describe a default priority or the queue
size limits of the various priority queues.
Assigning Priority by Protocol Type
Use the PRIORITY-LIST global configuration command to establish queuing
priorities based upon the protocol type. The full syntax of this command follows.
priority-list list protocol protocol-name queue-keyword [args]
no priority-list list protocol protocol-name queue-keyword
The argument list is an arbitrary integer between one and ten that identifies the
priority list selected by the user.
The keyword protocol is used with the argument protocol-name to specify the
protocol you are using and is one of the following: ip, pup, chaos, xns, decnet,
appletalk, clns, novell, apollo, vines, stun (for serial tunneling), or bridge
(for transparent bridging traffic).
The argument queue-keyword is a priority queue name; it can be high, medium,
normal, or low.

Adjusting Interface Characteristics 8–3

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
Optional arguments (args) can be specified, depending on the protocol-name
keyword, as follows:
•

gt byte-count—Specifies a greater-than count. The priority level assigned
goes into effect when a packet exceeds the value entered for the argument
byte-count. The size of the packet also must include additional bytes because
of MAC encapsulation on the outgoing interface.

•

lt byte-count—Specifies a less-than count. The priority level assigned goes
into effect when a packet size is less than the value entered for byte-count.
The size of the packet also must include additional bytes due to MAC
encapsulation on the outgoing interface.

•

bridge list list-number—Assigns the priority level to bridged traffic according
to the access list number using the bridge and list keywords. The list-number
argument is the Ethernet-type code access list number assigned by the
access-list global configuration command and the access-group list interface
subcommand.

•

list list-number—Assigns traffic priorities according to a specific list. The listnumber argument is the IP access list number assigned by the access-group
list interface subcommand. (For use with the IP protocol only.)

•

tcp port—Assigns the priority level defined to TCP segments originating
from or destined to a specified port (for use with the IP protocol only).
Table 8–1 lists common TCP services and their port numbers.

Table 8–1 Common TCP Services and Their Port Numbers
Service

Port

Telnet

SMTP

•

udp port—Assigns the priority level defined to UDP packets originating from
or destined to the specified port (for use with the IP protocol only). Table 8–2
lists common UDP services and their port numbers.

Table 8–2 Common UDP Services and Their Port Numbers
Service

Port

TFTP

NFS

2049

SNMP

161

RPC

111

DNS

Note
The TCP and UDP ports listed in Table 7-1 and Table 7-2 include some
of the more common port numbers. However, you can specify any port
number to be prioritized; you are not limited to those listed.

8–4 Adjusting Interface Characteristics

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
Use the NO PRIORITY-LIST global configuration command with the appropriate
arguments to remove an entry from the list.

Examples
This command assigns one as the arbitrary priority list number, specifies DECnet
as the protocol type, and assigns a high priority to the packets transmitted on
this interface.
priority-list 1 protocol decnet high
When classifying a packet, the system searches the list of rules specified by
PRIORITY-LIST commands for a matching protocol type. When a match is found,
the packet is assigned to the appropriate queue. The list is searched in the order
it is specified, and the first matching rule terminates the search.
This command assigns a medium priority level to every DECnet packet with a
size greater than 200 bytes.
!
priority-list 2 protocol decnet medium gt 200
!
This command assigns a medium priority level to every DECnet packet with a
size less than 200 bytes.
!
priority-list 4 protocol decnet medium lt 200
!
This command assigns a high priority to traffic that matches IP access list 10.
!
priority-list 1 protocol ip high list 10
!
This command assigns a medium priority level to Telnet packets.
!
priority-list 4 protocol ip medium tcp 23
!
This command assigns a medium priority level to UDP Domain Name service
packets.
!
priority-list 4 protocol ip medium udp 53
!
This command assigns a high priority to traffic that matches Ethernet type code
access list 201.
!
priority-list 1 protocol bridge high list 201
!
When using multiple rules for a single protocol, remember that the order of the
rules matters.

Adjusting Interface Characteristics 8–5

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
Assigning Priority by Interface Type
Use this variation of the PRIORITY-LIST global configuration command to
establish queuing priorities on packets entering from a given interface (full
syntax follows):
priority-list list interface interface-name queue-keyword
no priority-list list interface interface-name queue-keyword
The argument list is an arbitrary integer between one and ten that identifies the
priority list selected by the user.
The keyword interface applies to the priority queuing mechanism to packets
arriving from an interface. The argument interface-name specifies the name of
the interface.
The argument queue-keyword is a priority queue name; it can be high, medium,
normal, or low.
Use the NO PRIORITY-LIST command with the appropriate arguments to remove
an entry from the list.

Example
The following sample command sets any packet type entering on interface
Ethernet 2 to a medium priority:
!
priority-list 3 interface ethernet 2 medium
!
Assigning a Default Priority
Use the following global configuration command to assign a priority queue for
those packets that did not match any other rule in the priority list:
priority-list list default queue-keyword
no priority-list list default
If you do not specify a default or use the no form of the command, the normal
queue is assumed.
Specifying the Maximum Packets in the Priority Queues
Use this variation of the PRIORITY-LIST global configuration command to specify
the maximum number of packets that can be waiting in each of the priority
queues (full syntax shown):
priority-list list queue-limit high-limit medium-limit normal-limit low-limit
no priority-list list queue-limit
If a priority queue overflows, excess packets are discarded and quench messages
can be sent, if appropriate, for the protocol. The default queue-limit arguments
are 20 packets for the high priority queue, 40 for medium, 60 for normal, and
80 for low.
The NO PRIORITY-LIST command with the appropriate keywords and arguments
restores these defaults.

8–6 Adjusting Interface Characteristics

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
Example
The following is a sample of a priority list, including the access list referenced by
one of the priority list rules:
priority-list 1 protocol bridge high list 201
priority-list 1 protocol ip medium
priority-list 1 protocol decnet medium
priority-list 1 default low
priority-list 1 queue-limit 20 20 20 10
!
access-list 201 permit 0x6004 0x0000
!
Bridged traffic that matches access list 201 is given high priority. Because type
code 6004 is the local area transport (LAT), this rule assigns LAT traffic high
priority. IP and DECnet traffic are given medium priority, and everything else
is given low priority. In this instance, the network administrator has assigned
queue limits of 20 packets for every queue except the low-priority queue, which is
limited to 10 untransmitted packets.
Assigning a Priority Group to an Interface
Use the PRIORITY-GROUP interface subcommand to assign the specified priority
list to an interface.
priority-group list
no priority-group list
The argument list is the priority list number assigned to the interface. Multiple
lists can be assigned per interface.The no version of this command removes a
specific priority-group assignment if it includes a list argument. It removes all
priority-group assignments if specified without the list argument.
Example
This example causes packets exiting interface serial 0 to be classified by priority
list 1.
interface serial 0
priority-group 1
Monitoring the Priority Queuing Lists
When priority queuing is enabled on an interface, the EXEC command SHOW
INTERFACES displays information about the input and output queues. This
information is a triplet of numbers: the first is the number of packets currently
in the queue, the second is the maximum number of packets permitted in the
queue, and the third is the number of packets discarded because the queue is full.
Input queue: 0/75/4 (size/max/drops); Total output drops: 0
Output queue: high 0/20/0, medium 0/40/00, normal 0/60/0, low 0/80/0
The total output drops number is the sum of the discarded numbers from the
output queues, plus the count of packets discarded before being prioritized, or
because of fast-switching activity.

Adjusting Interface Characteristics 8–7

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
Assigning Priority by Serial Link Address
Use the PRIORITY-LIST global configuration command to establish queuing
priorities based on the address of the serial link on a STUN connection. The full
syntax of this command follows.
priority-list list stun queue-keyword address group-number address-number
no priority-list list stun queue-keyword address group-number addressnumber
The argument list is an arbitrary integer between 1 and 10 that identifies the
priority list selected by the user.
The keyword stun is used to indicate this is a serial tunnel feature.
The argument queue-keyword is a priority queue name; it can be high, medium,
normal or low.
The keyword address is used with the two arguments group-number and
address-number which uniquely identifies a STUN serial link. The argument
group-number is the group number used in the STUN GROUP interface
configuration subcommand. The argument address-number is the address of
the serial link. The format of the address number is either a one-byte hex value
(for example, C1) for an SDLC link or one that is specified by the STUN SCHEMA
configuration command.

Controlling Interface Hold Queues
Each network interface in a router has a hold-queue limit. This limit is the
number of data packets that the interface can store in its hold queue before
rejecting new packets. When the interface empties one or more packets from the
hold queue, the interface can accept new packets again.
To specify the hold-queue limit of an interface, use the HOLD-QUEUE interface
subcommand. Its full syntax is as follows:
hold-queue length {in | out}
no hold-queue {in | out}
The argument length is the maximum number of packets in the queue. The in
keyword specifies the input queue; the out keyword specifies the output queue.
The input hold queue prevents a single interface from flooding the router with
too many input packets. Further input packets are discarded if the interface
has too many input packets outstanding in the system. The default input hold
queue is 75 packets. The default output hold-queue limit is 40 packets. This
limit prevents a malfunctioning interface from consuming an excessive amount of
memory.
The NO HOLD-QUEUE command with the appropriate keyword restores the
default values for an interface. There is no fixed upper limit to a queue size.
If priority output queuing is being used, the length of the four output queues is
set using the PRIORITY-LIST global configuration command. The HOLD-QUEUE
command cannot be used to set an output hold queue length in this situation.

8–8 Adjusting Interface Characteristics

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
For slow links, use a small output hold-queue limit. This approach prevents
storing packets at a rate that exceeds the link’s transmission capability. For fast
links, use a large output hold-queue limit. A fast link may be busy for a short
time (and thus require the hold queue), but can empty the output hold queue
quickly when capacity returns.
To display the current hold queue setting and the number of packets discarded
because of hold queue overflows, use the EXEC command SHOW INTERFACES.
Note
Increasing the hold queue can have detrimental effects on network
routing and response times. For protocols that use seq/ack packets to
determine round-trip times, increasing the output queue is a very bad
idea. Dropping packets is not necessarily a bad thing—it informs hosts to
slow down transmissions to match available bandwidth. This is generally
better than having duplicate copies of the same packet within the network
(which can happen with large hold queues).

Setting Bandwidth
Higher-level protocols can use bandwidth information to make operating
decisions. For example, IGRP uses the minimum path bandwidth to determine a
routing metric. The TCP protocol adjusts initial retransmission parameters based
on the apparent bandwidth of the outgoing interface.
To set a bandwidth value for an interface, use the BANDWIDTH interface
subcommand. Its full syntax is as follows:
bandwidth kilobits
no bandwidth

Note
This is a routing parameter only; it does not affect the physical interface.
The argument kilobits specifies the intended bandwidth in kilobits per second.
For a full bandwidth DS3, enter the value 44736. Default bandwidth values
are set during startup and can be displayed with the EXEC command SHOW
INTERFACES.
The BANDWIDTH subcommand sets an informational parameter only; you
cannot adjust the actual bandwidth of an interface with it. For some media, such
as Ethernet, the bandwidth is fixed; for other media, such as serial lines, you
can change the actual bandwidth by adjusting hardware. For both classes of
media, you can use the BANDWIDTH subcommand to communicate the current
bandwidth to the higher-level protocols.
Use the NO BANDWIDTH command to restore the default values.

Adjusting Interface Characteristics 8–9

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
Setting Delay
As mentioned, higher-level protocols can use delay information to make operating
decisions. For example, IGRP can use delay information to differentiate between
a satellite link and a land link.
To set a delay value for an interface, use the DELAY interface subcommand. The
full syntax of this command follows.
delay tens-of-microseconds
no delay
The argument tens-of-microseconds specifies the delay for an interface or network
segment in tens of microseconds. Default delay values can be displayed with the
EXEC command SHOW INTERFACES. The NO DELAY command restores the
default.
Note
The DELAY subcommand sets an informational parameter only; you
cannot adjust the actual delay of an interface with this subcommand.

Setting and Adjusting Packet Sizes
Each interface has a default maximum packet size or maximum transmission
unit (MTU) size. This number generally defaults to the largest size possible for
that type interface. On serial interfaces, the MTU size varies, but cannot be
set smaller than 64 bytes. You can adjust the MTU using the MTU interface
subcommand.
mtu bytes
no mtu
The arguments bytes is the desired size in bytes. The NO MTU command
restores this value to its original default value. Table 8–3 lists default MTU
values according to media type.
Table 8–3 Default Media MTU Values
Media Type

Default MTU

Ethernet

1500

Serial

1500

Example
The following is an example of specifying the MTU on serial port to 300 bytes:
interface serial 1
mtu 1000

8–10 Adjusting Interface Characteristics

Adjusting Interface Characteristics
Adjusting Characteristics That Apply to All Interface Types
Note
Changing the MTU value with the MTU interface subcommand can affect
values for the protocol-specific versions of the command IP MTU and
CLNS MTU. If the current values specified with the IP MTU or CLNS
MTU interface subcommands are the same as the value specified with
the MTU interface subcommand, then when you change the value for
the MTU interface subcommand, the values for IP MTU and CLNS MTU
are automatically modified to match the new mtu interface subcommand
value. However, the reverse is not true. In other words, changing the
values for the IP MTU or CLNS MTU subcommands has no effect on the
value for the MTU interface subcommand.

Enabling the Loopback Test
The DECbrouter 90 software provides a loopback test to detect and distinguish
equipment malfunctions between line and modem or CSU/DSU (channel service
unit/digital service unit) problems on the router. If correct data transmission is
not possible when an interface is in loopback mode, the interface is the source
of the problem. The DSU may have similar loopback functions you can use to
isolate the problem if the interface loopback tests passes. If the device does not
support local loopback, this function will have no effect.
You can specify hardware loopback tests on Ethernet and serial interfaces that
are attached to CSU/DSUs and support the local loopback signal. The CSU/DSU
acts as a DCE device; the router as a DTE device. The local loopback test
generates a CSU loop—a signal that goes through the CSU/DSU to the line, then
back through the CSU/DSU to the router.
The PING command also can be useful during loopback operation; it is described
in Testing Connectivity with the PING Command in Chapter 6.
The following sections describe the various loopback tests available for the
supported interfaces.

Enabling Loopback on the Serial Interfaces
The serial interface supports the loopback function when a CSU/DSU or
equivalent device is attached to the router. Use the LOOPBACK interface
subcommand to enable loopback on the interface. The full syntax of this
subcommand follows.
loopback
no loopback
The LOOPBACK interface subcommand loops the packets through the CSU
/DSU to configure a CSU loop when the device supports this feature. The NO
LOOPBACK subcommand disables the function.

Enabling Loopback on the Ethernet Interface
The DECbrouter 90 Ethernet interface cannot be placed into loopback mode.

Adjusting Interface Characteristics 8–11

Adjusting Interface Characteristics
Global Configuration Subcommand Summary

Global Configuration Subcommand Summary
This section provides an alphabetical list of all the global configuration commands
described in this chapter.
[no] priority-list list default queue-keyword
Assigns a priority queue for those packets that did not match any other rule
in the priority list. If no default or the no form of the command is specified,
the normal queue is assumed.
[no] priority-list list interface interface-name queue-keyword
Sets up priority queuing on the specified interface. The keyword interface
applies to the priority queuing mechanism to packets arriving from an
interface. The argument interface-name specifies the name of the interface.
The arguments list and queue-keyword are described in the section Assigning
Priority by Interface Type. The no form of the command removes the item
from the list.
[no] priority-list list protocol protocol-name queue-keyword [args]
Sets up priority queuing on the specified interface. The keyword protocol
applies to the protocol you are using. The argument protocol-name specifies
the name of the protocol. The arguments list, queue-keyword, and the optional
args are described in the section Assigning Priority by Protocol Type. The no
form of the command removes the item from the list.
[no] priority-list list queue-limit high-limit medium-limit normal-limit
low-limit
Specifies the maximum number of packets that can be waiting in each of the
priority queues. If a priority queue overflows, excess packets are discarded
and quench messages can be sent, if appropriate, for the protocol. The no
form of the command resets all four queue sizes to their default values as
follows: high-limit = 20; medium-limit = 40; normal-limit = 60; low-limit =
80.
[no] scheduler-interval milliseconds
Controls the maximum amount of time that can elapse without running the
lowest-priority system processes. The minimum interval that can be specified
is 500 milliseconds; there is no maximum value. The default is to allow
high-priority operations to use as much of the central processor as needed.
The NO SCHEDULER-INTERVAL command restores that default.

8–12 Adjusting Interface Characteristics

Adjusting Interface Characteristics
Interface Configuration Subcommand Summary

Interface Configuration Subcommand Summary
This section provides an alphabetical list of all the interface commands described
in this chapter.
[no] bandwidth kilobits
Sets a bandwidth value for an interface. The argument kilobits specifies the
intended bandwidth in kilobits per second. Default bandwidth values are
set during startup and can be displayed with the EXEC command SHOW
INTERFACES. This is a routing parameter only; it does not affect the
physical interface. The no form of the subcommand restores the default.
[no] delay tens-of-microseconds
Sets a delay value for an interface. The argument tens-of-microseconds
specifies the delay for an interface or network segment in tens of
microseconds. Default delay values can be displayed with the EXEC
command SHOW INTERFACES. The no form of the subcommand restores
the default.
Note
The DELAY subcommand sets an informational parameter only; you
cannot adjust the actual delay of an interface with this subcommand.

hold-queue length {in | out}
no hold-queue {in | out}
Specifies the hold-queue limit of an interface. The argument length is the
maximum number of packets in the queue. The in keyword specifies the
input queue; the out keyword specifies the output queue. There is no fixed
upper limit to a queue size. The default for in is 75; the default for out is 40.
The no keyword restores the default values for an interface.
[no] loopback
On the serial interfaces—loops the packets through the CSU/DSU to configure
a "CSU loop," when the device supports this feature.
The no form of the subcommand disables the loopback test.
[no] mtu bytes
Adjusts the maximum transmission unit (MTU). The arguments bytes is the
desired size in bytes. The NO MTU subcommand restores this value to its
original default value.

Adjusting Interface Characteristics 8–13

Adjusting Interface Characteristics
Interface Configuration Subcommand Summary
[no] priority-group list
Assigns the specified priority group to an interface. The argument list is
the priority list number assigned to the interface. The no version of this
subcommand removes a specific priority-group assignment if it includes
a list argument. It removes all priority-group assignments if specified
without the list argument.
[no] pulse-time seconds
Enables pulsing DTR signals on the serial interfaces for a minimum interval
of seconds. The no version of the subcommand disables pulsing.
[no] transmitter-delay hdlc-flags
The argument hdlc-flags causes a minimum of HDLC flags to be sent between
each packet. The valid range is 2 to 62. The no form of the subcommand
restores the default value of zero flags.

8–14 Adjusting Interface Characteristics

9
Configuring Packet-Switched Software
This chapter describes the configuration tasks for packet-switched software.
These tasks include configuring the following protocols and services:
•

Recommendation X.25, including link access procedure, balanced (LAPB)

•

Connection-mode network service (CMNS) support to extend X.25 switching
support over LAN interfaces, as defined in ISO Standards 8208 (packet level)
and 8802-2 (frame level)

•

Frame relay service

•

Switched multimegabit data services (SMDS)

Summaries of the configuration commands available for these protocols and
services are provided at the end of this chapter.

Configuring LAPB
X.25 Level 2, or LAPB, is a data encapsulation protocol that operates at level
2 (the data link level) of the OSI reference model. LAPB specifies methods for
exchanging data (in units called frames), detecting out-of-sequence or missing
frames, retransmitting frames, and acknowledging frames.
It is possible to only use LAPB as a serial encapsulation method. This can
be done using a leased serial line. You must use one of the X.25 packet-level
encapsulations when attaching to an X.25 network.
Using LAPB under noisy conditions can result in greater throughput than HDLC
encapsulation. When LAPB detects a damaged frame, the router immediately
retransmits the frame instead of waiting for host timers to expire. However,
this behavior is good only if the host timers are relatively slow. In the case of
quickly expiring host timers, LAPB spends much of its time retransmitting host
retransmissions.
If the line is not noisy, the lower overhead of HDLC encapsulation is more
efficient than LAPB. When using long-delay satellite links, the lock step behavior
of LAPB makes the use of HDLC encapsulation the better choice.
The X.25 Recommendation distinguishes between two types of X.25 hosts:
data terminal equipment (DTE) in LAPB encapsulation host and data circuitterminating equipment (DCE) in LAPB encapsulation hosts.
A router using LAPB encapsulation can act as a DTE or DCE device at the
protocol level.

Configuring Packet-Switched Software 9–1

Configuring Packet-Switched Software
Configuring LAPB
Running a Single Network Protocol
To run datagrams of a single protocol over a serial interface using the LAPB
encapsulation, use the interface subcommand:
encapsulation {lapb | lapb-dce}
The keyword lapb sets DTE operation; the keyword lapb-dce sets DCE
operation. One end of the link must be DTE and the other must be DCE. By
default, the single protocol is IP.
To configure another protocol, use the interface subcommand:
lapb protocol keyword
Possible protocol keywords include ip, xns, decnet, appletalk, vines, clns,
novell, and apollo.

Running Multiple Network Protocols
To enable use of multiple network protocols on the same line at the same time,
use the keyword multi-lapb or multi-lapb-dce for DTE or DCE operation,
respectively.
encapsulation {multi-lapb | multi-lapb-dce}

For example, with the multi-lapb or multi-lapb-dce keyword, you can use IP,
DECnet, and XNS at the same time. Both ends of the line must use the same
encapsulation: either lapb or multi-lapb. One end of each line must be DCE.

Sample Configuration of LAPB Encapsulation
In the following example of LAPB encapsulation configuration, the frame size
(N1), window size (K), hold timer (TH), and maximum retransmission (N2)
parameters retain their default values. The ENCAPSULATION subcommand
sets DCE operation for IP packets only, and the LAPB T1 subcommand sets the
retransmission timer to 4,000 milliseconds (4 seconds).

Example
interface serial 3
encapsulation lapb-dce
lapb t1 4000
For more information on LAPB parameters, see the next section, Setting the X.25
Level 2 (LAPB) Parameters.

Setting the X.25 Level 2 (LAPB) Parameters
LAPB parameters are set with the LAPB interface subcommand. The interface
must be running with either the LAPB or X.25 encapsulation method specified
by the ENCAPSULATION interface subcommand. This subcommand takes two
required arguments, parameter and value. The argument parameter is one of
several keywords described in the following text, and the argument value is a
decimal number representing a period of time, a bit count, or a frame count,
depending on the parameter. Table 9–1 summarizes the LAPB parameters.
9–2 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring LAPB
Table 9–1 LAPB Parameters
Parameter

Value

Value Range

Default

Frames

1-7

Bits

1-16384

12000

Times

1-255

Milliseconds

1-64000

3000

Note
The LAPB "th" value is not included as a configurable parameter; the
value is always 0.

Setting the Retransmission Timer
The retransmission timer determines how long a transmitted frame can remain
unacknowledged before the router polls for an acknowledgment. To set the limit
for the retransmission timer (the LAPB T1 parameter), use the following interface
subcommand:
lapb t1 milliseconds
The argument milliseconds is the number of milliseconds from 1 through 64000.
The default value is 3,000 milliseconds.
For X.25 networks, the router retransmission timer setting should match
that of the network. Mismatched retransmission timers can cause excessive
retransmissions and an effective loss of bandwidth.
For leased-line circuits, the retransmission timer setting is critical. The timer
setting must be large enough to permit several maximum-sized frames to
complete one round trip on the link. If the timer setting is too small, the
router will poll before the acknowledgment frame can return, which results in
an effective loss of bandwidth. If the timer setting is too large, the router waits
longer than necessary before requesting an acknowledgment, which also reduces
bandwidth.
To determine an optimal value for the retransmission timer, use the privileged
EXEC command PING to measure the round-trip time of a maximum-sized frame
on the link. Multiply this time by a safety factor that takes into account the
speed of the link, the link quality, and the distance. A typical safety factor is
four. Choosing a larger safety factor can result in slower data transfer if the
line is noisy. However, this disadvantage is minor compared to the excessive
retransmissions and effective bandwidth reduction caused by a timer setting that
is too small.

Setting Frame Parameters
To specify the maximum number of bits a frame can hold, use the LAPB N1
interface subcommand:
lapb n1 bits

Configuring Packet-Switched Software 9–3

Configuring Packet-Switched Software
Configuring LAPB
The n1 keyword specifies the maximum number of bits (N1) a frame can hold.
The argument bits is the number of bits from 1 through 12,000 and must be a
multiple of eight. The default value is 12,000 bits (1500 bytes).
When connecting to an X.25 network, use the N1 parameter value set by the
network administration, which is the maximum size of an X.25 packet. When
using LAPB over leased lines, the N1 parameter should be eight times the MTU.
To specify the maximum number of times an acknowledgment frame can be
retransmitted, use the LAPB N2 interface subcommand:
lapb n2 retries
The argument retries is the retransmission count from 1 through 255. The default
value is 20 retransmissions.
To specify the maximum permissible number of outstanding frames, called the
window size, use the LAPB K interface subcommand:
lapb k window-size
The argument window-size is a packet count from one to seven. The default value
is seven packets.
Monitoring and Troubleshooting LAPB
To display operation statistics for an interface using LAPB encapsulation, use the
EXEC command SHOW INTERFACES.
The following example output shows the state of the LAPB protocol, the current
parameter settings, and a count of the different types of frames. Each frame
count is displayed in the form sent/received.
LAPB state is DISCONNECT, T1 3000, N1 12000, N2 20, K 7,TH 3000
IFRAMEs 12/28 RNRs 0/1 REJs 13/1 SABMs 1/13 FRMRs 3/0 DISCs 0/11
For a description of the variable names in the SHOW INTERFACE output, see
the X.25 Recommendation.
To debug LAPB problems, you must understand the X.25 recommendation.
To enable the logging of all packets received and generated, use the privileged
EXEC command DEBUG LAPB. Note that this command slows down processing
considerably on heavily loaded links. The following shows example output:
Serial0: LAPB O CONNECT (5) IFRAME 0 1
Serial0: LAPB I CONNECT (2) RR 1 (R)
Serial0: LAPB I CONNECT (5) IFRAME P 2 1 (C)
Serial0: LAPB O REJSENT (2) REJ P/F 1
Serial0: LAPB I REJSENT (2) DM F (C)
Serial0: LAPB I DISCONNECT (2) SABM (C)
Serial0: LAPB O CONNECT (2) UA
.
.
.
Serial0: LAPB T SABMSENT 357964 0
Serial0: LAPB O SABMSENT (2) SABM P
In the example output, each line represents a LAPB frame entering or exiting the
router. The first field shows the interface type and unit number of the interface

9–4 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring LAPB
reporting the frame event. The second field is the protocol that provided the
information.
The third field is I,O, or T for "frame input," "frame output," or "T1 timer
expired," respectively. The fourth field indicates the state of the protocol when the
frame event occurred. In a timer event, the state name is followed by the current
timer value and the number of retransmissions.
In a packet input or output event, the state name is followed by the size of the
frame in bytes (in parentheses) and the frame type name. The next field is an
optional indicator: P/F, P, or F, which stand for "Poll/Final," "Poll," and "Final,"
respectively. For IFRAME frames only, the next two numbers are the receive
and send sequence numbers, respectively. For RR, RNR, and REJ frames, the
next number is the receive sequence number. For FRMR frames, the next three
numbers are three bytes of error data. The last optional indicator is (C) or (R) for
"command" or "response," respectively.

Configuring X.25
The software for the router products supports the 1980 and 1984
Recommendation X.25 published by the French International Telegraph and
Telephone Consultative Committee (CCITT). The Recommendation specifies
connections between data terminal equipment (DTE) and data communications
equipment (DCE). The Defense Data Network (DDN) and the International
Standards Organization (ISO) specify the use of X.25 protocol for computer
communications. Many public and private networks also use Recommendation
X.25 as their interface technology.
Note
The DECbrouter 90 Configuration and Reference, Volume 3, Appendix
G, "X.25 Diagnostic Codes," describes the differences between the
DECbrouter 90 implementation of certain X.25 network-generated,
"international problem" diagnostic codes and the definitions provided in
Annex E of CCITT Recommendation X.25.
The X.25 model is a telephone network for computer data communications. To
start data communications, one computer system calls another to request a
communications session. The called computer system can accept or refuse the
call. If the called system accepts the call, the two computer systems can begin
transferring data in both directions; either system can terminate the call.
In addition to providing remote terminal access, X.25 networks provide bridging
capability using a growing list of protocols—the Internet Protocol (IP), DECnet,
XNS, ISO CLNS, AppleTalk, Novell IPX, Banyan VINES, and Apollo Domain.
The following sections provide an overview of the DECbrouter 90 X.25
implementation, describing the different encapsulation methods supported
by X.25 and X.25 as a datagram transport, with special attention to IP. This
is followed by descriptions of the DDN X.25 support provided by the router
and descriptions of how to configure X.25 switching and bridging. Finally, the
configurations of the X.25 Level 3 parameters and the X.25 Level 2 facilities are
discussed. A summary of the interface subcommands are provided at the end of
the chapter.

Configuring Packet-Switched Software 9–5

Configuring Packet-Switched Software
Configuring X.25
Note
The default values provided by the software are sufficient for most
X.25 networks; however, some parameters may need to be configured,
depending on the network.

Overview of Digital X.25 Support
DECbrouter 90 X.25 support can be used in two different ways:
•

As a transport for datagram traffic—This entails encapsulating datagrams
of IP, DECnet, and AppleTalk, inside packets on an X.25 virtual circuit.
Mappings between X.25 addresses and protocol addresses allow these
datagrams to be routed through an X.25 network. An X.25 Public Data
Network (PDN) is used to transport LAN protocols. See Figure 9–1 for a
representation of two routers sending data across an X.25 PDN.

•

As an X.25 switch—X.25 calls can be routed based on their X.25 addresses
either between serial interfaces on the same router (local switching) or across
an IP network to another router (remote switching, also called tunneling).
See point A in Figure 9–2 for an illustration of a local switching connection.
See point B in Figure 9–2 an illustration of a tunneling connection. Remote
X.25 switching encapsulates the X.25 packet-level inside a TCP connection,
allowing X.25 equipment to be connected via a TCP/IP-based network.
Note
When configuring IP routing over X.25, you may need to make
adjustments to accommodate split horizon effects. Refer to DECbrouter
90 Products, Configuration and Reference, Volume 2, Chapter 6, "The IP
Routing Protocols," for details about how the router handles possible split
horizon conflicts. By default, split horizon is enabled for X.25 networks.

S1156b

Figure 9–1 Transporting LAN Protocols Across an X.25 PDN

X.25
Public Data Network

DECbrouter 90
Router X

9–6 Configuring Packet-Switched Software

DECbrouter 90
Router Y

Configuring Packet-Switched Software
Configuring X.25
Figure 9–2 Routing X.25 Traffic Through a LAN

X.25 Host

Ethernet/IP LAN

DECbrouter 90
Router X

Public Data
Network

DECbrouter 90
Router Y

DECbrouter 90
Router Z

X.25 Host

S1154a

Transporting LAN Protocols Across an X.25 PDN
X.25 support is most commonly configured as a transport for datagrams across
an X.25 network. This is accomplished by first establishing a mapping between
protocol addresses (for example, IP or DECnet) and the X.121 addresses of the
X.25 network. When datagrams for a particular destination are routed for the
first time, a virtual circuit is set up to the appropriate X.121 address. The
Call User Data portion of the initial Call Request identifies the protocol of the
datagrams being carried by a particular virtual circuit. If multiple protocols are
in use, multiple virtual circuits will be opened.

X.25 Encapsulation Methods
This section describes the different encapsulation methods and commands that
are supported for commercial and private X.25 networks.
Encapsulation methods for DDN networks are described in the section
Configuring Datagram Transport on DDN Networks in this chapter.
A router using X.25 Level 3 encapsulation can act as a DTE or DCE X.25
interface.
To set X.25 DTE operation, use the ENCAPSULATION X25 interface
subcommand:
encapsulation x25
To set X.25 DCE operation, use the ENCAPSULATION X25-DCE interface
subcommand:
encapsulation x25-dce

Configuring Packet-Switched Software 9–7

Configuring Packet-Switched Software
Configuring X.25
Address Mapping Issues
To transport datagrams using X.25 Level 3, the router must map network protocol
addresses to X.121 addresses and vice versa. For example, Figure 9–3 illustrates
Hosts A and B that want to communicate via Routers X and Y, which have an
X.25 link between them.
Figure 9–3 Communicating via Routers Through an X.25 Network

DECbrouter 90
Router Y

Host
B
Primary
Host

X.25 Network

Host
A

DECbrouter 90
Router X
S1043a

Primary
Host

To send a packet to Host B, Host A must first send the packet to Router X. From
the destination address in the packet and from its routing information, Router
X determines that it must send the packet to Router Y over the X.25 network.
Router X must then determine the X.121 address for Router Y to open a virtual
circuit. Router X uses its network protocol-to-X.121 address map to convert the
protocol address of Router Y to the equivalent X.121 address. Router X can now
make the call to create a virtual circuit.
Except in the case of IP using DDN X.25 encapsulation, there is no standard
method for dynamically determining these mappings. Instead, static mapping
tables must be configured into each router.
To display the network protocol-to-X.121 address mapping, use the EXEC
command SHOW X25 MAP.
Setting Address Mappings
To specify a network-protocol-to-X.121 address mapping such as Internet-to-X.121
or DECnet-to-X.121, use the X25 MAP interface subcommand:
x25 map protocol-keyword protocol-address X.121-address [options]
no x25 map protocol-keyword protocol-address X.121-address

9–8 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Note
For bridging over X.25, there is no protocol address; however, the
broadcast option is required.
The argument protocol-keyword is one of these keywords:
•

ip—IP

•

decnet—DECnet

•

chaos—CHAOSnet

•

xns—XNS

•

novell—Novell IPX

•

appletalk—AppleTalk

•

vines—VINES

•

apollo—Apollo Domain

•

pup—PUP

•

bridge—Bridging

•

clns—OSI Connectionless Network Service

•

cmns—OSI Connection-Mode Network Service

•

compressedtcp—TCP header compression (This is discussed in more detail
in the section X.25 TCP Header Compression in this chapter.)

The address arguments specify the network-protocol-to-X.121 mapping.
The option arguments add certain features to the mapping specified and can be
any of the options that follow.
Note
These options cannot be configured with the x25 map cmns version of
the X25 MAP command.

•

accept-reverse—Causes the router to accept incoming reverse-charged calls.
If this option is not present, the router clears reverse-charged calls.

•

broadcast—Causes the router to direct any broadcasts sent through this
interface to the specified X.121 address. This option is needed when dynamic
routing protocols are being used to access the X.25 network, and is required
for bridging X.25.

•

cug number—Specifies a Closed User Group number (from 1 to 99) for the
mapping in the outgoing call.

•

modulo size—Specifies the window modulo for this map. The argument size
can be 8 or 128 to permit a maximum window size of 7 or 127, respectively.

•

nuid username password—Specifies that a network ID facility be sent in the
outgoing call with the specified user name and password.

Configuring Packet-Switched Software 9–9

Configuring Packet-Switched Software
Configuring X.25
•

nvc count—Sets the number of virtual circuits (VCs) for this protocol/host.
The default count is the x25 nvc setting of the interface. A maximum number
of eight VCs can be configured for each single protocol/host pair.

•

packetsize in-size out-size—Specifies input packet size (in-size) and output
packet size (out-size) for the mapping in the outgoing call.

•

reverse—Specifies reverse charging for outgoing calls.

•

rpoa name—Specifies the list of transit recognized private operating agencies
(RPOAs) to use in outgoing call request packets for this x25 map entry.

•

throughput in out—Requests the amount of bandwidth through the X.25
network.

•

transit-delay number—Specifies the transit delay value in milliseconds (0 to
65334) for the mapping in of outgoing calls for networks that support transit
delay.

•

windowsize in-size out-size—Specifies input window size (in-size) and output
window size (out-size) for the mapping in the outgoing call.

To retract a network protocol-to-X.121 mapping, use the NO X25 MAP interface
subcommand with the appropriate network protocol and X.121 address
arguments.
Configuring X.25 to Allow Ping Support over Multiple Lines
For PING commands to work in an X.25 environment (when load sharing over
multiple serial lines), you must include entries for all adjacent interface IP
addresses in the X25 MAP command for each serial interface. The example
configuration that follows illustrates this point.

Example
For example, consider two routers, Router A and Router B, communicating with
each other over two serial lines via an X.25 PDN (see Figure 9–4) or over leased
lines. In either case, all serial lines must be configured for the same IP subnet
address space. In order to allow for successful PING commands, the configuration
might be as in the lists that follow. In any event, a similar configuration is
required for the same subnet IP addresses to work across X.25.
Figure 9–4 Parallel Serial Lines to X.25 Network

DECbrouter 90
Router A

S0
S1

X.25
Packet Switched
Network

S0
S1

DECbrouter 90
Router B

S1044a

9–10 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Note
All four serial ports configured for the two routers in the following
configuration example must be assigned to the same IP subnet address
space. In this case, the subnet is 131.108.170.0.

! Configuration for Router A
! ------------------------int s 0
ip 131.108.170.1 255.255.255.0
x25 address 11
x25 map ip 131.108.170.3 31370054065
x25 map ip 131.108.170.4 31370054065
int s 1
ip 131.108.170.2 255.255.255.0
x25 address 12
x25 map ip 131.108.170.4 31370054067
x25 map ip 131.108.170.3 31370054067
! Configuration for Router B
! ------------------------int s 0
ip 131.108.170.3 255.255.255.0
x25 address 13
x25 map ip 131.108.170.1 31370054068
x25 map ip 131.108.170.2 31370054068
int s 1
ip 131.108.170.4 255.255.255.0
x25 address 14
x25 map ip 131.108.170.2 31370054069
x25 map ip 131.108.170.1 31370054069
Setting Encapsulation Permanent Virtual Circuits
Permanent virtual circuits (PVCs) are the X.25 equivalent of leased lines; they are
never disconnected. To establish a PVC, use the X25 PVC interface subcommand:
x25 pvc circuit protocol-keyword protocol-address [option]
no x25 pvc circuit protocol-keyword protocol-address
The argument circuit is a virtual-circuit channel number and must be less
than the virtual circuits assigned to the switched virtual circuits (SVCs). The
argument protocol-keyword can be one of these keywords:
•

ip—IP

•

decnet—DECnet

•

chaos—CHAOSnet

•

xns—XNS

•

novell—Novell IPX

•

appletalk—AppleTalk

•

vines—VINES

Configuring Packet-Switched Software 9–11

Configuring Packet-Switched Software
Configuring X.25
•

apollo—Apollo Domain

•

pup—PUP

•

bridge—Bridging

The argument protocol-address is that of the host at the other end of the PVC.
The optional argument option is used to specify the PVC’s flow control parameters
if they differ from the interface defaults. The option arguments add certain
features to the mapping specified and can be any of the options that follow.
•

•

modulo size—Specifies the window modulo for this map. The argument size
can be 8 or 128 to permit a maximum window size of 7 or 127, respectively.

•

packetsize in-size out-size—Specifies input packet size (in-size) and output
packet size (out-size) for the mapping in the outgoing call.

•

windowsize in-size out-size—Specifies input window size (in-size) and output
window size (out-size) for the mapping in the outgoing call.

PVCs are not supported for ISO CMNS. Switched virtual circuits (SVCs) are
sufficient for CMNS connections over X.25.
Note
You must specify the required network protocol-to-X.121 address mapping
with an X25 MAP subcommand before you can set up a PVC. See the
Setting Address Mappings section earlier in this chapter for a description
of that command.
To delete a PVC, use the NO X25 PVC interface subcommand with the
appropriate channel number, protocol keyword, and protocol address.
Note
When configuring X.25 to use a PVC, you must ensure that no traffic is
sent toward a remote terminal server between the time the X25 MAP
command is issued and the time that the X25 PVC command is issued.
Otherwise, the local system will create a switched virtual circuit (SVC),
and then the X25 PVC command will not be allowed.
Map entries with the broadcast attribute are particularly likely to get
traffic, due to routing protocol traffic. The simplest way to ensure that
traffic is not sent while configuring an interface to use a PVC is to shut
down the interface while configuring it for PVC support.

9–12 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Example
This example, illustrated in Figure 9–5, demonstrates how to use the PVC
to exchange IP traffic between Router X and Router Y. In this example, the
PDN has established a PVC through its network connecting PVC number 3 of
access point A to PVC number 4 of access point B. On Router X a connection
is established between Router X and Router Y’s IP address, 131.108.1.4. On
Router Y a connection is established between Router Y and Router X’s IP address,
131.108.1.3.
Router X> x25 map ip 131.108.1.3 0
interface serial 2
x25 pvc 3 ip 131.108.1.3
Router Y> x25 map ip 131.108.1.4 0
interface serial 3
x25 pvc 4 ip 131.108.1.4

Figure 9–5 Establishing a PVC through an X.25 Network
131.108.1.4
Serial 2
A

DECbrouter 90
Router X
PVC 3

Serial 3
X.25
Public Network

DECbrouter 90
Router Y

S1156a

131.108.1.3

PVC 4

Protocol-to-Virtual Circuit Mapping
The call request packet that sets up a virtual circuit contains a field called call
user data (CUD). Typically, the software uses the first byte of CUD to distinguish
which high-level protocol will be carried by a particular virtual circuit.
Table 9–2 lists the hexadecimal values of the initial byte of CUD and its
corresponding network level protocol. The use of 0x81 for ISO 8473 (CLNS)
is an ISO standard. The use of 0xCC for Department of Defense IP is defined by
RFC 877. The use of C0 00 80 C4 is defined by Banyan. The other values are
meaningful only to this software. All the values are padded with three bytes of
0x00, except for VINES, the BFE X.25 encapsulation, and CLNS, all of which
follow ISO 8473 requirements.

Configuring Packet-Switched Software 9–13

Configuring Packet-Switched Software
Configuring X.25
Table 9–2 Protocols and Initial Byte of Call User Data
Protocol

Initial CUD Byte

ISO CLNS

0x81

DOD IP

0xCC

PUP

0xCE

Chaosnet

0xCF

DECnet

0xD0

XNS

0xD1

AppleTalk

0xD2

Novell

0xD3

Apollo Domain

0xD4

VINES

0xC0 0x00 0x80xC4

Bridges

0xD5

Call User Data (CUD)

0xd8

To set the default protocol, use the X25 DEFAULT command. The full syntax
follows:
x25 default protocol
no x25 default protocol
The X25 DEFAULT command specifies the protocol assumed by the router to
interpret calls with unknown CUD. The argument protocol sets the default
protocol and is either IP or PAD. Use this subcommand to change the action
taken when an incoming call is received without identifying CUD. Normally, the
call is cleared. When you use this subcommand, the incoming call is assumed to
contain the specified default protocol.
The NO X25 DEFAULT subcommand removes the protocol specified.
Displaying Address Mappings
To display the network-protocol-to-X.121 address mappings, enter this command
at the EXEC prompt:
show x25 map
The following is a sample output. It is followed by Table 9–3, which describes the
fields in the output. The output includes a configuration that uses TCP header
compression over X.25.

9–14 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Serial0: novell 10.0.0c00.7b22 000000220200 PERMANENT, 1 LCN: 4*
Serial0: IP 10.1.0.1 000000010100 CONSTRUCTED
Serial1: appletalk 128.1 000000010000 PERMANENT
Serial1: decnet 28.1 000000020000 PERMANENT BROADCAST
Serial1: ip 128.1.0.3 000000030000 PERMANENT, 2 LCN: 1023*, 1024
Serial1: COMPRESSEDTCP 128.1.0.4 000000111111 PERMANENT
Compression statistics
Interface Serial1:
Rcvd:
4060 total, 2891 compressed, 0 errors
0 dropped, 1 buffer copies, 0 buffer failures
Sent:
4284 total, 3224 compressed,
105295 bytes saved, 661973 bytes sent
1.15 efficiency improvement factor
Connect: 16 slots, 1543 long searches, 2 misses, 99% hit ratio
Five minute miss rate 0 misses/sec, 0 max misses/sec
Serial1: IP 128.1.0.4 000000111111 PERMANENT
Note
Instead of being interface-specific, statistics for TCP header compression
over X.25 are specific to each compressed TCP map entry. This is in
contrast to the output for the command SHOW IP TCP HEADERCOMPRESSION, which is described in the DECbrouter 90 Configuration
and Reference, Volume 2.

Table 9–3 Show X25 Map Field Descriptions
Field

Description

Interface name

Example of interface name.

Protocol type

Protocol type.

Protocol address

First address: Source protocol address. Second
address: X.121 address mapping.

Address mapping type

Address-mapping type examples:
PERMANENT: entered with x25 map interface
subcommand.
INTERFACE: indicates address of a router network
interface.
CONSTRUCTED: derived using the DDN address
conversion scheme.
BROADCAST: appears on the output line if broadcasts
are enabled for an address mapping.

LCN

Logical circuit numbers. If the LCN is greater than
zero, a list of the LCNs for the protocol/X.121 address
is displayed. An asterisk marks the current LCN.

Rcvd:
Total

Total number of TCP packets received.

Compressed

Total number of TCP packets compressed.

Errors

Unknown packets.

Dropped

Number of packets dropped due to invalid
compression.
(continued on next page)

Configuring Packet-Switched Software 9–15

Configuring Packet-Switched Software
Configuring X.25
Table 9–3 (Cont.) Show X25 Map Field Descriptions
Field

Description

Buffer copies

Number of packets that had to be copied into bigger
buffers for decompression.

Buffer failures

Number of packets dropped due to a lack of buffers.

Sent:
Total

Total number of TCP packets sent.

Compressed

Total number of TCP packets compressed.

Bytes saved

Number of bytes reduced.

Bytes sent

Number of bytes sent.

Efficiency improvement factor

Improvement in line efficiency because of TCP header
compression.

Connect:
Number of slots

Size of the cache.

Long searches

The number of times the software had to look to find a
match.

Misses

The number of times a match could not be made. If
your output shows a large miss rate, then the number
of allowable simultaneous compression connections
may be too small.

Hit ratio

Percentage of times the software found a match and
was able to compress the header.

Five minute miss rate

Calculates the miss rate over the previous five minutes
for a longer-term (and more accurate) look at miss rate
trends.

Example X.25 Configuration
The following example shows the complete configuration for a serial interface
connected to a commercial X.25 PDN for routing the IP. The IP subnetwork
address 131.108.9.0 has been assigned for the X.25 network.
Note
When routing IP over X.25, the X.25 network must be treated as a single
IP network or subnetwork. Map entries for routers with addresses on
subnetworks other than the one on which the interface’s IP address is
stored are ignored by the routing software. Additionally, all routers using
the subnet number should have map entries for all others. There are
also issues with the broadcast flag, which apply both to IP and to other
protocols with dynamic routing.

9–16 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
interface serial 1
ip address 131.108.9.1 255.255.255.0
!
encapsulation X25
!
! The "bandwidth" command is not part of the X.25
! configuration; it’s especially important to understand that it doesn’t
! have any connection with the X.25 entity of the same name.
!"bandwidth" commands are used by IP routing processes (currently only IGRP),
! to determine which lines are the best choices for traffic.
! Since the default is 1544, and X.25 service at that rate isn’t generally
! available, most X.25 interfaces that are being used with IGRP in a
! real environment will have "bandwidth" settings.
!
! This is a 9.6 Kbaud line:
!
bandwidth 10
!
! These Level 3 parameters are defaults; they need to
! match the PDN defaults. They are negotiable on a per-call basis:
!
x25 win 7
x25 wout 7
x25 ips 512
x25 ops 512
!
! You must specify an X.121 address to be assigned to the X.25 interface by
! the PDN.
!
x25 address 31370054065
!
! The following Level 3 parameters have been set to match the network.
! You generally need to change some Level 3 parameters, most often
! those listed below. You may not need to change any Level 2
! parameters, however.
!
x25 htc 32
x25 idle 5
x25 nvc 2
!
! The following commands configure the X.25 map. If you want to exchange
! routing updates with any of the routers, they would need "broadcast" flags.
! If the X.25 network is the only path to them, static routes are
! generally used to save on packet charges. If there is a redundant path,
! it might be desirable to run a dynamic routing protocol.
!
x25 map IP 131.108.9.3 31370019134 ACCEPT-REVERSE
! (ACCEPT-REVERSE allows collect calls)
x25 map IP 131.108.9.1 31370054065
x25 map IP 131.108.9.2 31370053087
!
! If the PDN cannot handle fast back-to-back packets,use the
!"transmitter-delay" command to slow down the interface:
!
transmitter-delay 50

Configuring Packet-Switched Software 9–17

Configuring Packet-Switched Software
Configuring X.25
Routing X.25 Traffic through a LAN
In addition to transporting datagrams, the X.25 software implementation allows
virtual circuits to be forwarded from one X.25 interface to another and from one
router to another. The forwarding behavior can be controlled with switching and
tunneling commands, based on a locally built table.
Higher-level protocols can share an X.25 encapsulated serial interface with the
X.25 switching support. Switching or forwarding X.25 virtual circuits can be done
two ways:
•

Incoming calls received from a local serial interface running X.25 can be
forwarded to another local serial interface running X.25. This is known as
local X.25 switching, because the router handles the complete path. It does
not matter whether the interfaces are configured as DTE or DCE, because
software will take the appropriate actions.

•

An incoming call also can be forwarded to another router over a LAN using
the TCP/IP protocols. Upon receipt of an incoming call, a TCP stream
connection is established to the router that is acting as the switch for the
destination. All X.25 packets are sent and received over this reliable data
stream. Flow control is maintained from local interface to remote interface.
This is known as remote X.25 switching, or tunneling. It does not matter
whether the interfaces are configured as DTE or DCE, because software will
take the appropriate actions.

Running X.25 over TCP/IP provides a number of benefits. The IP datagram
containing the X.25 packet can be switched by other routers using their highspeed switching abilities. X.25 connections can be sent over networks running
only the TCP/IP protocols. The TCP/IP protocol suite runs over many different
networking technologies, including Ethernet and T1 serial. Thus X.25 data can
be forwarded over these media to another router, where it can be output to an
X.25 interface.
When the connection is made locally the switching command is used, and when
the connection is across a LAN the tunneling command is used. The basic
switching (or tunneling) function is the same for both types of connections, but
different software commands are required for the two types of connections.
The X.25 switching subsystem supports the following facilities and parameters:
•

The D-bit ignored but passed through transparently

•

Variable-length interrupt data

•

Flow control parameter negotiation
— Window size up to 7
— Packet size up to 1024

•

The basic closed user group selection

•

Throughput class negotiation

•

Reverse charging and fast select

•

Stripped local facilities

9–18 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Enabling X.25 Switching
The X25 ROUTING command enables local switching or tunneling (used for
remote switching), allowing you to route X.25 traffic through a LAN. To enable
X.25 switching or tunneling, use the following global command:
x25 routing
no x25 routing
X.25 calls will not be forwarded until this command is issued. The command NO
X25 ROUTING disables the forwarding of X.25 calls.
Constructing the X.25 Routing Table
The X.25 routing table is consulted when an incoming call is received that should
be forwarded. The called (destination) X.121 address and CUD fields of the X.25
packet are used to determine the route.
An entry in the X.25 routing table is set up or removed with the x25 route global
configuration commands. The full syntax and variations of these commands
follows:
x25 route [# position] x121-pattern [cud pattern] interface interface-name
no x25 route [# position] x121-pattern [cud pattern] interface interfacename
x25 route [# position] x121-pattern [cud pattern] ip ip-address
no x25 route [# position] x121-pattern [cud pattern] ip ip-address
x25 route [# position] x121-pattern [cud pattern] alias interface-name
no x25 route [# position] x121-pattern [cud pattern] alias interface-name
The order in which X.25 routing table entries are specified is significant; the
list is scanned linearly for the first match. The optional argument # position (#
followed by an integer) can be used to designate after which existing entry to
insert or delete the new entry. If no positional parameter is given, the entry is
appended to the end of the routing table.
The argument x121-pattern can be either an actual x.121 destination address or a
regular expression representing a group of X.121 addresses.
The argument pattern is a regular expression that must match the called address
and is required. Optional CUD corresponding to that X.121 address can be
specified as a printable ASCII string. Both the X.121 address and Call User Data
can be written using UNIX-style regular expressions. The Call User Data field
specifies the data after the protocol identification field, which is four bytes. Use
the SHOW X25 ROUTE command to display the X.25 routing table.
The alias keyword permits a way for other X.121 addresses to be treated as local.
An alias accepts calls for the router.
Enter the NO X25 ROUTE command with the appropriate arguments and
keywords to remove the entry from the table.

Configuring Packet-Switched Software 9–19

Configuring Packet-Switched Software
Configuring X.25
Translating X.25 Called Addresses
When interconnecting two separate X.25 networks, it is sometimes necessary to
provide for address translation. Your X.25 switch supports translation of X.25
called and calling addresses using the substitute-dest or substitute-source
keyword with the X25 ROUTE configuration subcommand. Addresses can be
rewritten using regular expression replacement.
The substitute-source keyword allows substitution of the calling address. For
backwards compatibility, the substitute keyword will be accepted as substitutedest and written to nonvolatile memory in the new format. When used with the
X25 USE-SOURCE-ADDRESS command, this option allows the calling address to
be modified.
x25 route [# position] x121-pattern [substitute-source rewrite-pattern]
[substitute-dest rewrite-pattern] [cud pattern] interface destinationinterface
For typographical reasons, this command is shown on two lines. When using
the optional keywords in this variation of the X25 ROUTE subcommand, the
substitute-source keyword must precede the substitute-dest keyword, and
both must precede the cud keyword. The entire command must be on one line.
The argument x121-pattern can be either an actual x.121 destination address or a
regular expression representing a group of X.121 addresses.
The argument rewrite-pattern will replace the called or calling X.121 address
in routed X.25 packets, as appropriate. The backslash (\) character is treated
specially in the argument rewrite-pattern; it indicates that the digit immediately
following it selects a portion of the original called address to be inserted in the
new called address. The characters \0 are replaced with the entire original
address. The characters \1 through \9 are replaced with the strings that
matched the first through ninth parenthesized parts of X121-pattern. See
Table 9–4 and Table 9–5 for a summary of pattern and character matching.
A more complete description of the pattern-matching characters can be found in
the DECbrouter 90 Configuration and Reference, Volume 3, Appendix D.
Table 9–4 Pattern Matching
Pattern

Matching

Replaces entire original address

\ 1..9

Replaces strings that match first through ninth parenthesized part of X.121
address

Matches 0 or more sequences of the regular expressions

Matches 1 or more sequences of the regular expressions

Matches the regular expression of the null string

9–20 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Table 9–5 Character Matching
Character

Matching

Matches the null string at the beginning of the input string

Matches the null string at the end of the input string

\ char

Matches char

Matches any single character

Example
This example indicates that X.25 calls to addresses whose first four data network
identification code (DNIC) digits are 1111 should be routed through interface
serial 3, but that the DNIC field in the addresses presented to the equipment
connected to that interface should be changed to 2222. The \1 characters in
the rewrite pattern indicate the portion of the original address matched by the
characters. The asterisk should be inserted in the rewritten address.
x25 route ^1111(.*) substitute-dest 2222\1 interface serial 3
Figure 9–6 shows a more contrived example intended to illustrate the power of
the rewriting scheme.
Figure 9–6 X.121 Address Translation Scheme
(. . . .) . . (. .) . . (. .) (. .) substitute \2\4\3\1 interface serial 0
\4
\3
\2
\1

S1046a

x25 route

This sample would cause all X.25 calls with 14-digit called addresses to be routed
through interface serial 0. The incoming DNIC field would be moved to the end
of the address. The fifth, sixth, ninth, and tenth digits would be deleted, and the
thirteenth and fourteenth would be moved before the eleventh and twelfth.
Configuring Switched PVCs
You can configure X.25 permanent virtual circuits (PVCs) in the X.25 switching
software. This means that DTEs that require permanent circuits can be
connected to the router acting as an X.25 switch and have a properly functioning
connection. X.25 RESETs will be sent to indicate when the circuit comes up or
goes down. Use the X25 PVC interface subcommand to configure a PVC for a
given interface. The syntax of this command follows.
x25 pvc pvc-number1 interface interface-name pvc pvc-number2 [option]
The argument pvc-number1 is the PVC number that will be used on the local
interface (as defined by the primary interface command). The argument pvcnumber2 is the number that will be used on the remote interface. The argument
interface-name is the remote interface type and unit number (serial 0, for
example), as specified by the INTERFACE command. The option arguments
add certain features to the mapping specified and can be any of the options that
follow.
Configuring Packet-Switched Software 9–21

Configuring Packet-Switched Software
Configuring X.25
•

packetsize in-size out-size—Specifies input packet size (in-size) and output
packet size (out-size) for the mapping in the outgoing call.

•

windowsize in-size out-size—Specifies input window size (in-size) and output
window size (out-size) for the mapping in the outgoing call.

Example
Consider a PVC connected between two serial interfaces on the same router.
In this type of interconnection configuration, the alternate interface must be
specified along with the PVC number on that interface. To make a working PVC
connection, two commands must be specified, each pointing to the other as this
example illustrates.
interface serial 0
encapsulation x25
x25 ltc 5
x25 pvc 1 interface serial 1 pvc 1
interface serial 1
encapsulation x25
x25 ltc 5
x25 pvc 1 interface serial 0 pvc 1

X.25 Switching Configuration Examples
The following two examples illustrate how to enable an X.25 switch, how to
enable call forwarding, and how to configure a router on a Tymnet/PAD switch to
accept and forward calls.

Examples
This configuration shows how to enable X.25 switching, as well as how to enter
routes into the X.25 routing table.
!
! Enable X.25 forwarding
x25 routing
!
! Enter routes into the table. Without a positional parameter, entries
! are appended to the end of the table
x25 route ^100$ interface serial 0
x25 route 100 cud ^pad$ interface serial 1
x25 route .* ip 10.2.0.2
!
This routing table forwards calls for X.121 address 100 out via interface serial 0.
Otherwise, if the X.121 address contains 100 anywhere within it and the CUD is
the string pad, it is forwarded onto serial 1. All other X.121 addresses will match
the third entry, which is a match-all pattern and will have a TCP connection
established to the IP address 10.2.0.2. The router at 10.2.0.2 will then route the
call according to its X.25 routing table.
This example configures a router that sits on a Tymnet/PAD switch to accept calls
and have them forwarded to a Digital VAX system. This feature permits running
X.25 network over a generalized, already existing IP network, thereby making it
unnecessary to get another physical line for one protocol.

9–22 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
The router positioned next to the Digital VAX system is configured with X.25
routes, as follows:
x25 route vax-x121-address interface serial 0
x25 route.* ip Digital-on-tymnet-ipaddress
This routes all calls to the Digital VAX X.121 address out to serial 0, where the
VAX system is connected running PSI. All other X.121 addresses are forwarded to
the Digital-on-tymnet address using its IP address. This takes all outgoing calls
from the VAX system and sends them to Digital-on-tymnet for further processing.
On the router named Digital-on-tymnet, you would enter these commands:
x25 route vax-x121-address ip Digital-on-vax
x25 route .* interface serial 0
This forces all calls with the VAX X.121 address to be sent to the router with the
VAX system connected to it. All other calls with X.121 addresses are forwarded
out to Tymnet. If Tymnet can route them, a CALL ACCEPTED packet is
returned, and everything proceeds normally. If Tymnet cannot handle it, it
clears the call, and the CLEAR REQUEST packet is forwarded back toward the
VAX system.

Setting the X.25 Parameters
The DECbrouter 90 software provides subcommands to configure the standard
Level 2 and Level 3 X.25 parameters and user facilities. This section discusses
the commands and procedures needed to set these parameters, including interface
addresses, virtual circuit ranges, and addresses.
Once you establish X.25 Level 3 encapsulation, you can set X.25 Level 3
parameters. These parameters are described in the following sections.
Note
If you connect a router to an X.25 network, use the parameters set by
the network administrator. Also, note that the X.25 Level 2 parameters
described in Setting the X.25 Level 2 (LAPB) Parameters earlier in this
chapter can be configured on an X.25 interface and affect X.25 Level 3
operations.

Setting the X.25 Interface Address
To set the X.121 address of a particular network interface, use the X25 ADDRESS
subcommand. The address is assigned by the X.25 network.
x25 address X.121-address
The argument X.121-address is a variable-length X.121 address.

Example
The following subcommand sets the X.121 address of the current interface to
address 2:
x25 address 2
The value must match that assigned by the X.25 network.
Configuring Packet-Switched Software 9–23

Configuring Packet-Switched Software
Configuring X.25
The section DDN X.25 Dynamic Mapping in this chapter describes the addressing
scheme for DDN X.25 networks.
Configuring Virtual Circuit Ranges
The X.25 protocol maintains multiple connections over one physical link between
a DTE and a DCE. These connections are called virtual circuits (VCs) or logical
channels (LCs). X.25 can maintain up to 4095 VCs numbered 1 through 4095; an
individual VC is identified by giving its logical channel identifier (LCI) or virtual
circuit number (VCN). Many networking documents use VC and LC, and VCN,
LCN, and LCI interchangeably; they all mean the same thing.
An important part of X.25 operation is virtual circuit number ranges. Virtual
circuit numbers are broken into four ranges (listed here in numerically increasing
order):
1. Permanent virtual circuits (PVCs)
2. Incoming-only circuits
3. Two-way circuits
4. Outgoing-only circuits
The incoming-only, two-way, and outgoing-only ranges define the VC numbers
over which switched virtual circuits (SVCs) can be established by placing X.25
calls, much like a telephone network establishes a switched voice circuit when a
call is placed.
Rules about DCE and DTE devices initiating calls are as follows:
•

Only the DCE device can initiate a call in the incoming-only range.

•

Only the DTE device can initiate a call in the outgoing-only range.

•

Both the DCE device and the DTE device can initiate a call over a virtual
circuit number in two-way range.

There is no difference in the operation of the SVCs other than restrictions on
which devices can initiate calls. These ranges can be used to prevent one side
from monopolizing the virtual circuits and are useful for X.25 interfaces that have
only a small total number of SVCs available.
Six X.25 parameters define the upper and lower limits of each of the three SVC
ranges. An SVC range cannot overlap another range. A PVC must be assigned a
number that is lower than the numbers assigned to the SVC ranges. All ranges
are assigned by the network administrator and must fall between 1 and 4095.
To set the SVC range upper- and lower-limit parameters, use the X25
subcommand keywords listed in Table 9–6. Each keyword takes a circuit number
as its argument. Note that the values for these parameters must be the same
on both ends of an X.25 link; for connection to a public data network (PDN),
these values must be set to the values assigned by the network. An SVC range is
unused if its upper and lower limits are set to 0.
Note
Because the X.25 protocol requires the DTE and DCE to have identical VC
ranges, the DECbrouter 90 implementation will not allow an interface’s
VC ranges to be modified while the X.25 line protocol is up.

9–24 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Table 9–6 Range Limit Keywords for the Switched Virtual Circuit Ranges
Keyword

Limit Type

Range

Default

lic

Lower limit, incoming-only circuits

1-4095

hic

Upper limit, incoming-only circuits

1-4095

ltc

Lower limit, two-way circuits

1-4095

htc

Upper limit, two-way circuits

1-4095

1024

loc

Lower limit, outgoing-only circuits

1-4095

hoc

Upper limit, outgoing-only circuits

1-4095

Setting the Lowest Incoming-only Circuit Number
The lic keyword sets the lowest incoming-only virtual circuit number.
x25 lic circuit-number
The argument circuit-number is a virtual circuit number from 1 through 4095, or
0 if there is no incoming-only VC range. The default value is 0.
Setting the Highest Incoming-only Circuit Number
The hic keyword sets the highest incoming-only virtual circuit number.
x25 hic circuit-number
The argument circuit-number is a virtual circuit number from 1 through 4095, or
0 if there is no incoming-only virtual circuit range. The default value is 0.
Setting the Lowest Two-way Circuit Number
The ltc keyword sets the lowest two-way virtual circuit number.
x25 ltc circuit-number
The argument circuit-number is a virtual circuit number from 1 through 4095, or
0 if there is no two-way virtual circuit range. The default value is 1.
Setting the Highest Two-way Circuit Number
The htc keyword sets the highest two-way virtual circuit number.
x25 htc circuit-number
The argument circuit-number is a virtual circuit number from 1 through 4095, or
0 if there is no two-way virtual circuit range. The default value is 1024 for X.25
network service interfaces; 4095 for connection-mode network service (CMNS)
interfaces.
Setting the Lowest Outgoing-only Circuit Number
The loc keyword sets the lowest outgoing-only virtual circuit number.
x25 loc circuit-number
The argument circuit-number is a virtual circuit number from 1 through 4095, or
0 if there is no outgoing-only virtual circuit range. The default value is 0.

Configuring Packet-Switched Software 9–25

Configuring Packet-Switched Software
Configuring X.25
Setting the Highest Outgoing-only Circuit Number
The hoc keyword sets the highest outgoing-only virtual circuit number.
x25 hoc circuit-number
The argument circuit-number is a virtual circuit number from 1 through 4095, or
0 if there is no outgoing-only virtual range. The default value is 0.

Example
The configuration in this example sets the following virtual circuit ranges: 5-20
dedicated to incoming calls only (from the DCE to the DTE), 25-1024 for either
incoming or outgoing calls, no virtual circuit range dedicated to outgoing calls
(from the DTE to the DCE). Up to four permanent virtual circuits can be defined
on the virtual circuit numbers 1 through 4.
x25 lic 5
x25 hic 20
x25 ltc 25
Maintaining Virtual Circuits
The router can clear a switched virtual circuit after a set period of inactivity. To
set this period, use the X25 IDLE interface subcommands:
x25 idle minutes
no x25 idle
The argument minutes is the number of minutes in the period. The default value
is zero, which causes the router to keep the SVC open indefinitely. Calls both
originated and received by the router are cleared. The NO X25 IDLE command
returns to the default.
To increase datagram throughput across an X.25 network, you can establish up to
eight SVCs to a host. To specify the maximum number of SVCs that can be open
simultaneously to one host, use the X25 NVC interface subcommand:
x25 nvc count
The argument count is a circuit count from 1 to 8; the default is 1. A maximum of
eight VCs can be configured for each protocol/host pair. This value should not be
set greater than 1 for use with protocols that do not tolerate out-of-order delivery
such as switched X.25 and encapsulated TCP header compression.
When the windows and output queues of all existing connections to a host are
full, a new virtual circuit will be opened to the designated circuit count. If a new
connection cannot be opened the data is dropped.
Note
The count value specified for x25 nvc affects the default value for the
number of SVCs. It does not affect the NVC value for any X25 MAP
commands that already have been configured.

9–26 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Configuring the Ignore VC Timer
Upon receiving a Clear Request for an outstanding Call Request, the X.25 support
code immediately tries another Call Request if it has more traffic to send. This
can overrun some X.25 switches. To prevent this problem, use the X25 HOLDVC-TIMER configuration commands:
x25 hold-vc-timer minutes
no x25 hold-vc-timer
The argument minutes is the number of minutes to prevent calls from trying to
reach a previously failed destination. Incoming calls still will be accepted. The
default value is 0; the NO X25 HOLD-VC-TIMER command restores this default.
Configuring the X.25 Level 3 Retransmission Timers
The X.25 Level 3 retransmission timers determine how long the router must
wait before retransmitting various Request packets. You can set these timers
independently using the X25 subcommand keywords listed in Table 9–7. Each
keyword requires a time value in seconds as its argument. The last column shows
the default timer values in seconds. Four of the timers apply to DTE devices and
the other four to DCE devices.
Table 9–7 Retransmission Timer Keywords and Defaults
Keyword
(DTE/DCE)

Affected
Request Packet

Time (seconds)
(DTE/DCE)

Time
(seconds)
(DXE)

t20/t10

Restart Request

180/60

t21/t11

Call Request

200/180

180

t22/t12

Reset Request

180/60

t23/t13

Clear Request

180/60

180

Note
When setting this timer for a CMNS configuration, you are setting it for a
DXE interface, which can be either DTE or DCE.

Setting the DTE Restart Request Retransmission Timer
The t20 keyword sets the limit for the Restart Request retransmission timer
(T20) on DTE devices.
x25 t20 seconds
The argument seconds is a time value in seconds. The default is 180 seconds.
Setting the DCE Restart Request Retransmission Timer
The t10 keyword sets the limit for the Restart Request retransmission timer
(T10) on DCE devices.
x25 t10 seconds
The argument seconds is a time value in seconds. The default value is 60 seconds.

Configuring Packet-Switched Software 9–27

Configuring Packet-Switched Software
Configuring X.25
Setting the DTE Call Request Limit Timer
The t21 keyword sets the limit for the Call Request completion timer (T21) on
DTE devices.
x25 t21 seconds
The argument seconds is a time value in seconds. The default value is 200
seconds.
Setting the DCE Call Request Limit Timer
The t11 keyword sets the limit for the Call Request completion timer (T11) on
DCE devices.
x25 t11 seconds
The argument seconds is a time value in seconds. The default value is 180
seconds.
Setting the DTE Reset Request Retransmission Timer
The t22 keyword sets the limit for the Reset Request retransmission timer (T22)
on DTE devices.
x25 t22 seconds
The argument seconds is a time value in seconds. The default value is 180
seconds.
Setting the DCE Reset Request Retransmission Timer
The t12 keyword sets the limit for the Reset Request retransmission timer (T12)
on DCE devices.
x25 t12 seconds
The argument seconds is a time value in seconds. The default value is 60 seconds.
Setting the DTE Clear Request Retransmission Timer
The t23 keyword sets the limit for the Clear Request retransmission timer (T23)
on DTE devices.
x25 t23 seconds
The argument seconds is a time value in seconds. The default value is 180
seconds.
Setting the DCE Clear Request Retransmission Timer
The t13 keyword sets the limit for the Clear Request retransmission timer (T13)
on DCE devices.
x25 t13 seconds
The argument seconds is a time value in seconds. The default value is 60 seconds.

9–28 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Updating the X.121 Address
Some X.25 calls, when forwarded by the X.25 switching support, need the calling
(source) X.121 address updated to that of the outgoing interface. This is necessary
when forwarding calls from private data networks to public data networks.
Outgoing calls forwarded over a specific interface can have their calling X.121
addresses updated by using the X25 USE-SOURCE-ADDRESS subcommand. The
full syntax is as follows:
x25 use-source-address
no x25 use-source-address
The NO X25 USE-SOURCE-ADDRESS command prevents updating the source
addresses of outgoing calls.
Setting X.25 Packet Sizes
X.25 networks use maximum input and output packet sizes set by the network
administration. You can set the router input and output packet sizes to
match those of the network with the x25 subcommand keywords ips and ops,
respectively:
x25 ips bytes
x25 ops bytes
The argument bytes is a byte count in the range of 16 through 1024. The default
value is 128 bytes.
Larger packet sizes are better than smaller ones, because smaller packets require
more overhead processing.
Note
Set the x25 ips and x25 ops keywords to the same value unless your
network supports asymmetry between input and output packets.
To send a packet larger than the X.25 packet size over an X.25 virtual circuit,
a router must break the packet into two or more X.25 packets with the M-bit
("more data" bit) set. The receiving device collects all packets with the M-bit set
and reassembles them.
Note
For optimal throughput, all X.25 interfaces that may carry routed traffic
through an IP network should be configured with the same default packet
sizes and window sizes.

Setting the Flow Control Modulus
X.25 supports flow control with a sliding window sequence count. The window
counter restarts at zero upon reaching the upper limit, which is called the
window modulus. To set the window modulus, use the X25 MODULO interface
subcommand:
x25 modulo modulus

Configuring Packet-Switched Software 9–29

Configuring Packet-Switched Software
Configuring X.25
The argument modulus is either 8 or 128. The default value is 8. The value of
the modulo parameter must agree with that of the device on the other end of the
X.25 link.
Configuring Packet Acknowledgment
To specify upper limits on the number of outstanding unacknowledged packets,
use the commands X25 WIN (for input window) and x25 wout (for output
window).
x25 win packets
x25 wout packets
The argument packets is a packet count. The packet count for win and wout
must be between one and modulus minus one. The default value is two packets.
Note
For optimal throughput, all X.25 interfaces that may carry routed traffic
through an IP network should be configured with the same default packet
sizes and window sizes.
The X25 WIN command determines how many packets the router can receive
before sending an X.25 acknowledgment. The wout limit determines how many
sent packets can remain unacknowledged before the router uses a hold queue. To
maintain high bandwidth use, assign these limits the largest number that the
network allows.
Note
Set win and wout to the same value unless your network supports
asymmetry between input and output window sizes.
You can instruct the router to send acknowledgment packets when it is not busy
sending other packets, even if the number of input packets has not reached
the win count. This approach improves line responsiveness at the expense of
bandwidth. To enable this option, use the X25 TH subcommand:
x25 th delay
The argument delay must be between zero and the input window size. A value
of one sends one Receiver Ready acknowledgment per packet at all times. The
default value is zero, which disables the delayed acknowledgment strategy. A
delay value smaller than the window value may be advisable to smooth the data
flow of large messages transmitted on serial leased lines to X.25 networks.
The router sends acknowledgment packets when the number of input packets
reaches the count you specify, providing there are no other packets to send. For
example, if you specify a count of one, the router can send an acknowledgment
per input packet.

9–30 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Suppressing the Calling Address
To omit the calling address in outgoing calls, use the X25 SUPRESS-CALLINGADDRESS interface subcommand:
x25 suppress-calling-address
no x25 suppress-calling-address
The suppress-calling-address keyword omits the calling (source) X.121 address
in Call Request packets. This option is required for networks that expect only
subaddresses in the calling address field. The calling address is sent by default.
Use the NO X25 SUPPRESS-CALLING-ADDRESS subcommand to reset this
subcommand to the default state.
Suppressing the Called Address
To omit the called address in outgoing calls, use the X25 SUPPRESS-CALLEDADDRESS interface subcommand:
x25 suppress-called-address
no x25 suppress-called-address
The suppress-called-address keyword omits the called (destination) X.121
address in Call Request packets. This option is required for networks that expect
only subaddresses in the called address field. The called address is sent by
default.
Use the NO X25 SUPPRESS-CALLED-ADDRESS subcommand to reset this
subcommand to the default state.
Defining a Packet Hold Queue
To define the number of packets to be held until a virtual circuit is established,
use the X25 HOLD-QUEUE interface subcommand:
x25 hold-queue queue-size
no x25 hold-queue [queue-size]
The argument queue-size defines the number of packets. By default, this number
is zero. Use the NO X25 HOLD-QUEUE command without an argument to
remove this command from the configuration file; enter the command with a
queue size value of zero to return the default.
Accepting Reverse-Charged Calls
To instruct the router to accept all reverse-charged calls, use the X25 ACCEPTREVERSE interface subcommand:
x25 accept-reverse
no x25 accept-reverse
The accept-reverse keyword causes the interface to accept reverse-charged calls
by default. This behavior also can be configured on a per-peer basis using the
X25 MAP subcommand. The NO X25 ACCEPT-REVERSE command disables this
facility.

Configuring Packet-Switched Software 9–31

Configuring Packet-Switched Software
Configuring X.25
Forcing Packet-Level Restarts
To force a packet-level restart when the link level is restarted, use the X25
LINKRESTART interface subcommand:
x25 linkrestart
no x25 linkrestart
This command restarts X.25 Level 2 (LAPB) when errors occur. This behavior is
the default and is necessary for networks that expect this behavior. Use the no
x25 linkrestart to turn this feature off.
Use of the NO X25 LINKRESTART command is strongly discouraged except
when connecting to networks that require packet-level restart to be turned off.
LAPB frames can be duplicated or lost when LAPB errors occur, which can cause
problems for the X.25 packet layer. These problems can be avoided if the packet
layer is notified of the LAPB error, causing a restart of the X.25 service.
Setting the Packet Network Carrier
To set the packet network carrier, use the X25 RPOA interface subcommand:
x25 rpoa name number
no x25 rpoa name
The X25 RPOA interface subcommand specifies a list of transit RPOAs to use,
referenced by name. The argument name must be unique with respect to all
other RPOA names. It is used in the X25 FACILITY and X25 MAP interface
subcommands. The argument number is a number that is used to describe an
RPOA. The NO X25 RPOA command removes the specified name.
Setting X.25 Parameters on a Per-Call Basis
To override interface settings on a per-call basis, use the X25 FACILITY interface
subcommand. The full syntax of the command follows.
x25 facility keyword argument
no x25 facility keyword argument
The command enables X.25 facilities, which are sent between DTE and DCE
devices to negotiate certain link parameters.
The argument keyword specifies one of the following keywords, followed by the
required argument:
•

cug number—Specifies a closed user group number from 1 through 99 to
provide an extra measure of network security.

•

packetsize in-size out-size—Sets the size in bytes of input packets (in-size)
and output packets (out-size). Both values should be the same.

•

reverse—Reverses charges on all Call Request packets from the interface.

•

windowsize in-size out-size—Sets the packet count for input windows (insize) and output windows (out-size). Both values should be the same.

•

throughput in out—-Sets the requested throughput values for input and
output throughput across the network.

9–32 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
•

rpoa name0—Specifies the list of transit recognized private operating
agencies (RPOAs) to use in outgoing Call Request packets.

•

transit-delay number—Specifies the transit delay value in milliseconds (0 to
65334) for the mapping in of outgoing calls, for networks that support transit
delay.

The NO X25 FACILITY command with the appropriate keyword and argument
removes the facility.
X.25 TCP Header Compression
TCP header compression is supported over X.25 links through the use of the X25
MAP COMPRESSEDTCP interface subcommand:
x25 map compressedtcp
The implementation of compressed TCP over X.25 uses a virtual circuit (VC) to
pass the compressed packets. The noncompressed packets use another VC.
The interface subcommand X25 MAP COMPRESSEDTCP is required to make the
X.25 calls complete for compressed packets. The command syntax is:
x25 map compressedtcp ip-address x.121-address [options]
no x25 map compressedtcp ip-address x.121-address [options]
The argument ip-address is the IP address, and x.121-address is the X.121
address. The options argument accepts the same options as those for the X25
MAP command described in the preceding section, but includes the following
additional option:
•

passive—This keyword applies to compressed TCP mappings. If this option
is specified, outgoing packets are compressed only if incoming TCP packets on
the VC for this map are compressed. When the passive option is not set, all
compressible traffic intended for this address map is compressed.
Note
You cannot configure the X25 MAP command’s NVC option with a value
that is more than one compressed TCP map. If you attempt to do so, the
router generates an error message indicating that it cannot be done.

The CUD of compressed TCP calls is the single byte 0xd8.

Note
Typically, the DECbrouter 90 uses the first byte of Call User Data to
distinguish which high-level protocol will be carried by a particular
virtual circuit.
The NO X25 MAP COMPRESSEDTCP disables TCP header compression for the
link.

Configuring Packet-Switched Software 9–33

Configuring Packet-Switched Software
Configuring X.25
Bridging on X.25
The DECbrouter 90 transparent bridging software supports bridging of X.25
frames. To configure this capability, add this variation of the X25 MAP interface
subcommand to the bridging configuration file:
x25 map bridge X.121-address broadcast [options-keywords]
The command specifies Internet-to-X.121 address mapping. The keyword bridge
specifies bridging over X.25. The argument X.121-address is the X.121 address.
The keyword broadcast is required for bridging X.25 frames. The argument
options-keywords represents services that can be added to this map. See the
section Setting Address Mappings earlier in this chapter. For further information
about bridging on X.25 and for an example configuration, refer to the DECbrouter
90 Configuration and Reference, Volume 3, Chapter 7, "Configuring Transparent
Bridging."

Configuring Datagram Transport on DDN Networks
The Defense Data Network (DDN) X.25 protocol has two versions: basic service
and standard service. Using DDN X.25 basic service, network devices send raw
X.25 data across the DDN and assume no structure within the data portion of the
X.25 packet. Basic service users can interoperate only with other basic service
users.
DDN X.25 standard service requires that the X.25 data packets carry IP
datagrams. Because the DDN packet-switch nodes (PSNs) can extract an
Internet packet from within an X.25 packet, they can pass data to either an
1822-speaking host or to another standard service host. Thus, hosts using the
older 1822 network interface can interoperate with hosts using standard service.
The DDN X.25 Standard is the required protocol for use with DDN PSNs. The
Defense Communications Agency (DCA) has certified DECbrouter 90’s DDN X.25
Standard implementation for attachment to the DDN.
Enabling DDN X.25
A router using DDN X.25 basic service can act as either a DTE or a DCE device.
To set operation type, use the encapsulation interface subcommand:
encapsulation {ddnx25 | ddnx25-dce}
Both of these keywords cause the router to specify the standard service facility in
the Call Request packet, which notifies the PSNs to use standard service.
Using standard service, the DDN can provide efficient service for virtual circuits
with high-precedence values. If the router receives an Internet packet with a
nonzero Internet precedence field, it opens a new virtual circuit and sets the
precedence facility request to the DDN-specified precedence mapping in the Call
Request packet. Different virtual circuits are maintained based on the precedence
mapping values and the number of virtual circuits permitted.

9–34 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Blacker Emergency Mode
For environments that require a high level of security, your router software
supports the Defense Data Network Blacker Front-End Encryption (BFE) and
Blacker Emergency Mode.
Blacker Emergency Mode allows your BFE device and your router to function in
emergency situations. When the router is configured to participate in emergency
mode and the BFE device is in emergency mode, the router sends address
translation information to the BFE device to assist the it in sending information.
The DECbrouter 90’s implementation of Blacker Emergency Mode adheres to the
specifications outlined in the DCA Blacker Interface Control document, published
March 21, 1989.
BFE Device Configuration
Your BFE device is configured to be in one of three possible modes as follows:
•

Enters emergency mode when requested to by the network. If the router
is configured to respond to a BFE device in emergency mode, or if the
EXEC command BFE ENTER is used, the router sends address translation
information to the BFE device.

•

Never enters emergency mode.

•

Notifies the router that emergency mode window is open and waits for the
router to tell it to enter emergency mode. If the router is configured to
respond to a BFE in emergency mode, or if the EXEC command bfe enter is
used, the router sends a special address translation packet to the BFE device.
The "special" data includes a command to the BFE to enter emergency mode.

Router Configuration
If the router is attached to a BFE device, the bfex25 keyword must be used
with the ENCAPSULATION subcommand. Use this command to configure BFE
encapsulation:
encapsulation bfex25
This encapsulation provides a mapping from Class A IP addresses to the type of
X.121 addresses expected by the BFE encryption device.
The table resulting from the following x25 REMOTE-RED command provides the
address translation information the router sends to the BFE when the BFE is in
emergency mode. Use the following command to set up the table that lists the
BFE nodes (host or gateways) to which the router will send packets:
x25 remote-red host-ip-address remote-black Blacker-Internet-address
The host-ip-address argument is the IP address of the host or a router that
the packets are being sent to. The Blacker-Internet-address argument is the IP
address of the remote BFE device in front of the host that the packet is being
sent to.
Use the following command to configure the circumstances under which the
router will participate in emergency mode:
x25 bfe-emergency {never | always | decision}

Configuring Packet-Switched Software 9–35

Configuring Packet-Switched Software
Configuring X.25
The default keyword is never. When set to never, the router does not send
address translation information to the BFE. When it does not receive address
translation information, the BFE cannot open a new connection for which it does
not know the address.
When the always keyword is used and the router has been configured to create
an address translation table, the router passes address translations to the BFE
when the BFE enters emergency mode.
When the decision keyword is used, the router waits until it receives a
diagnostic packet from the BFE device indicating that the emergency mode
window is open. (The window is only open when a condition exists that allows the
BFE is to enter emergency mode.) When the diagnostic packet is received, the
router’s participation in emergency mode depends on how it is configured using
the X25 BFE-DECISION command described next in this section.
Use the following command to configure how a router configured as X25 BFEEMERGENCY DECISION will participate in emergency mode:
x25 bfe-decision {no | yes | ask}
The default value is no. When set to no, the router will not participate in
emergency mode and will not send address translation information to the BFE.
When set to yes, the router will participate in emergency mode, sending address
translation information to the BFE when the BFE enters emergency mode. The
router gets this information from the table setup by using the x25 remote-red
command described earlier in this section.
When the ask keyword is used, the router will prompt the administrator to
use the EXEC BFE {ENTER | LEAVE} command to send or not send address
translation information to the BFE device.
Use the following interface EXEC command to set the router to participate in
emergency mode or to end participation in emergency mode if your system is
configured for x25 bfe-emergency decision and x25 bfe-decision ask.
bfe {enter | leave} interface-type unit

The keyword options are enter and leave. The keyword enter will cause the
router to send a special address translation packet that includes an "enter
emergency mode" command to the BFE if the emergency mode window is open.
If the BFE is already in emergency mode, this command enables the sending of
address translation information.
If the BFE is in emergency mode, the leave keyword disables the sending of
address translation information from the router to the BFE device.
The interface-type argument is the interface name, and unit is the interface
number.

9–36 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
Example
In the example that follows, interface Serial 0 is configured to require an EXEC
command from the administrator before it participates in emergency mode. The
host IP address is 21.0.0.12, and the address of the remote BFE unit is 21.0.0.1.
When the BFE enters emergency mode, the router will prompt the administrator
for EXEC command BFE ENTER to direct the router to participate in emergency
mode.
interface serial 0
x25 bfe-emergency decision
x25 remote-red 21.0.0.12 remote-black 21.0.0.1
x25 bfe-decision ask
Monitoring Blacker Emergency Mode
Use the following command to display the one-to-one mapping of the host IP
addresses and the remote BFE device’s IP addresses:
show x25 remote-red
When all of the X.25 bfe nodes (host or gateways) are entered by using the
X25 REMOTE-RED command, the SHOW command that follows can be used to
display the table.

Example
The following show display provides the IP addresses of the host unit (remote-red)
and remote BFE units (bfe-remote) for each BFE entry:
router> show x25 remote-red
Entry Remote-red bfe-remote Interface
1 21.0.0.3 21.0.0.7 serial3
2 21.0.0.10 21.0.0.6 serial1
3 21.0.0.24 21.0.0.8 serial3
DDN X.25 Dynamic Mapping
The DDN X.25 standard implementation includes a scheme for dynamically
mapping all classes of Internet addresses to X.121 addresses without a table.
This scheme requires that the Internet addresses conform to the formats shown
in Figure 9–7. These formats segment the Internet addresses into network (N),
host (H), logical address (L), and IMP (I) portions. (The acronym IMP, which
stands for interface message processor, is the predecessor of PSN, which stands
for packet switch node.) For the BFE encapsulation, the Internet address is
segmented into Port (P), Domain (D), and BFE ID number (B).

Configuring Packet-Switched Software 9–37

Configuring Packet-Switched Software
Configuring X.25
Figure 9–7 DDN Internet/X.121 Address Conventions

Net.Host.LH.PSN
8 8 8 8

0000 0 PPPHH00

Class B:
Bits:

Net.Net.Host.LH.PSN
8 8 8 8

0000 0 PPPHH00

Class C:
Bits:

Net.Net.Net.Host.PSN
8 8 8 4 4

0000 0 PPPHH00

Class BFE:
Bits:

Net.unused.Port.Domain.BFE
8 1 3 10 10

0000 0 PDDDBBB

S1045a

Class A:
Bits:

The DDN conversion scheme uses the host and IMP portions of an Internet
address to create the corresponding X.121 address. Strictly speaking, the DDN
conversion mechanism is limited to Class A Internet addresses. However, the
router can convert Class B and Class C addresses as well. As indicated in Table
8-8, this method uses the last two octets of a Class B address as the host and
IMP identifiers, and the upper and lower four bits in the last octet of a Class C
address as the host and IMP identifiers, respectively.
The DDN conversion scheme uses a physical address mapping if the host
identifier is numerically less than 64. (This limit derives from the fact that a
PSN cannot support more than 64 nodes.) If the host identifier is numerically
larger than 64, the resulting X.121 address is called a logical address. The DDN
does not use logical addresses.
The format of physical DDN X.25/X.121 addresses is ZZZZFIIIHHZZ(SS), where
each character represents a digit. ZZZZ represents four zeros, F is zero to indicate
a physical address, III represents the IMP (PSN) octet from the Internet address
padded with leading zeros, HH is the host octet from the Internet address padded
with leading zeros, and ZZ represents two zeros. (SS) represents the optional and
unused subaddress.
The physical and logical mappings of the DDN conversion scheme always
generate a 12-digit X.121 address. Subaddresses are optional; when added to
this scheme, the result is a 14-digit X.121 address. The DDN does not use
subaddressing.
Packets using routing and other protocols that require broadcast support
can successfully traverse X.25 networks, including the DDN. This traversal
requires the use of network protocol-to-X.121 maps because the router must
know explicitly where to deliver broadcast datagrams. (X.25 does not support
broadcasts.) You can mark network protocol-to-X.121 map entries to accept
broadcast packets; the router then sends broadcast packets to hosts with marked
entries. If you do not specify the address for an interface configured for DDN
X.25, the router uses the DDN mapping technique to obtain the X.121 address of
an interface.
To display the network protocol-to-X.121 address mapping, enter this command at
the EXEC prompt:
show x25 map

9–38 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
DDN X.25 Configuration Subcommands
Normally the X.25 parameters of a DDN connection are configured using the x25
and lapb interface subcommands described earlier in this chapter. There are a
few DDN-specific subcommands, however.
This X.25 implementation allows you to enable or disable the ability to open a
new virtual circuit based on the IP type of service (TOS) field.
To do this, use the X25 IP-PRECEDENCE interface subcommand. The full syntax
of this command follows.
x25 ip-precedence
no x25 ip-precedence
By default, the router opens one virtual circuit for each TOS> There is a problem
associated with this in that some hosts send nonstandard data in the TOS field,
thus causing multiple, wasteful virtual circuits to be created. The command
no x25 ip-precedence causes the TOS field to be ignored when opening virtual
circuits.

Maintaining X.25
To clear all virtual circuits at once, use the privileged EXEC command CLEAR
X25-VC. This command takes an interface type keyword and a unit number as
arguments to identify the interface with which the virtual circuits are associated.
To clear a particular virtual circuit, add the two arguments described above the
CLEAR X25-VC command, and include a logical circuit number (LCN) value as a
third argument. The command syntax is as follows:
clear x25-vc interface unit [lcn]
The CLEAR X25-VC command clears all X.25 virtual circuits at once. The
argument interface is the interface type. The argument unit is the interface unit
number. The optional argument lcn clears the specified virtual circuit.

Monitoring X.25 Level 3 Operations
The router provides EXEC SHOW commands to provide information on interface
and virtual circuit operation. Use the EXEC command SHOW INTERFACES to
display interface parameters and statistics. Use the EXEC command SHOW X25
VC to display virtual circuit parameters and statistics.
Displaying Interface Parameters and Statistics
To display parameter information for a serial interface using the X.25 Level 3
protocol, use the EXEC command SHOW INTERFACES. To display X.25 Level 3
parameters for LAN interfaces (such as Ethernet), use the SHOW CMNS EXEC
command described later in this chapter. For serial X.25 interfaces, the following
is an example of output:
X25 address 000000010100, state R1, modulo 8, idle 0, timer 0, nvc 1
Window size: input 2, output 2, Packet size: input 128, output 128
Timers: T20 180 T21 200 T22 180 T23 180 TH 0
Channels: Incoming 1-1024 Two-way 1-1024 Outgoing 1-1024
RESTARTs 1/20 CALLs 1000+2/1294+190/0+0 DIAGs 0/0
Window is closed
On the first line, the address field indicates the calling address used in the Call
Request packet. The state field indicates the state of the interface: R1 is the
Configuring Packet-Switched Software 9–39

Configuring Packet-Switched Software
Configuring X.25
normal-ready state, R2 indicates the DTE not-ready state, and R3 indicates
the DCE not-ready state. If the state is R2 or R3, the device is awaiting
acknowledgment for a Restart Request packet. The modulo field displays the
modulo value, which determines the sequence numbering scheme used. The idle
field shows the number of minutes the router waits before closing idle virtual
circuits. The timer field displays the value of the interface timer, which is zero
unless the interface state is R2 or R3. The nvc field displays the maximum
number of simultaneous virtual circuits permitted to and from a single host.
On the second line, the Window size and Packet size fields show the default
window and packet sizes for the interface. Each virtual circuit can override
these values using facilities specified with the X25 MAP or X25 FACILITY
subcommands.
The third line shows the values of the Request packet timers (T10 through
T13 for a DCE device, and T20 through T23 for a DTE device). The fourth line
shows the channel sequence ranges. The last line shows packet statistics for the
interface using these formats:
sent/received\ successful+failed\ callssent+callssentfailed/\
callsreceived+callsreceivedfailed/\
callsforwarded+callsforwardedfailed\
Displaying General Virtual Circuit Parameters and Statistics
The EXEC command SHOW X25 VC displays the details of the active X.25
switched virtual circuits. To examine a particular virtual circuit, add an LCN
argument to the SHOW X25 VC command. The following is example output:
LC1: 1, State: D1, Interface: Serial0
Started 0:55:03, last input 0:54:56, output 0:54:56
Connected to IP [10.4.0.32] <Ð>000000320400
Window size input: 7, output: 7
Packet size input: 1024, output: 1024
PS: 2 PR: 6 Remote PR: 2 RCNT: 1 RNR: FALSE
Retransmits: 0 Timer (secs): 0 Reassembly (bytes): 0
Held Fragments/Packets: 0/0
Bytes 1111/588 Packets 18/22 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
On the first line, the LCI field displays the virtual circuit number. The State
field displays the state of the virtual circuit (which is independent of the states
of other virtual circuits); D1 is the normal ready state. (See the CCITT X.25
recommendation for a description of virtual circuit states.) The Interface field
shows the interface used for the virtual circuit.
On the second line, the Started field shows the time elapsed since the virtual
circuit was created, the last input field shows time of last input, and the output
field shows time of last output.
The third line describes the type of connection provided. This example shows a
circuit that can be used to exchange IP traffic with the network-protocol address
10.4.0.32, and that the connection was made using the displayed X.121 address.
This line will change depending on the type of connectivity. For example, a
locally switched PVC would cause a display on this line similar to the following:
Switched PVC to serial PVC 3 connected. Before a circuit is fully established
(that is, the call has not yet been accepted) this line will report that the SVC is a
half-baked connection.
The Precedent field, which appears only if you have specified DDN encapsulation,
indicates IP precedence.

9–40 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring X.25
The fourth and fifth lines show window and packet sizes. These sizes can differ
from the interface default values if facilities were offered and accepted in the Call
Request and Call Accepted packets.
On the sixth line, the PS and PR fields show the current send and receive
sequence numbers, respectively. The Remote PR field shows the last PR number
received from the other end of the circuit. The RCNT field shows the count of
unacknowledged input packets. The RNR field shows the state of the Receiver Not
Ready flag; this field is true of the network sends a receiver-not-ready packet.
On the seventh line, the Retransmits field shows the number of times a packet
has been retransmitted. The Timer field shows a nonzero time value if a packet
has not been acknowledged or if virtual circuits are being timed for inactivity.
The Reassembly field shows the number of bytes received for a partial packet (a
packet in which the more data bit is set).
On the eighth line, the Fragments part of the Held Fragments/Packets field
shows the number of X.25 packets being held. (In this case, Fragments refers
to the X.25 fragmentation of higher-level data packets.) The Packets part of
the Held Fragments/Packets field shows the number of higher-level protocol
packets currently being held pending the availability of resources, such as the
establishment of the virtual circuit.
On the last line, the Bytes field shows the total numbers of bytes sent and
received. The Packets, Resets, RNRs, REJs, and INTs fields show the total sent
and received packet counts of the indicated types. (RNR is receiver not ready,
REJ is reject, and INT is interrupt).

Debugging X.25
When installing an X.25 link, you can use the EXEC commands DEBUG with
different keywords as follows:
debug x25
Enables the monitoring of all X.25 traffic.
debug x25-events
Enables the monitoring of all X.25 traffic but does not display information
about X.25 data or acknowledgment packets.
debug x25-vc number
Allows you to watch the specified port number with a virtual circuit using the
DEBUG X25 and DEBUG X25-EVENTS commands.

Configuring Packet-Switched Software 9–41

Configuring Packet-Switched Software
Configuring X.25
The following is example output:
Serial0 (704760940): X25 O R2 RESTART (5) 8 lci 0 cause 0 diag 0
Serial0 (704760944): X25 I R2 RESTART (5) 8 lci 0 cause 7 diag 0
Serial0 (704762944): X25 O D2 RESET REQUEST (5) 8 lci 1 cause 0 diag 0
Serial0 (704762952): X25 I D2 RESET CONFIRMATION (3) 8 lci 1
Serial0 (704763372): X25 O P2 CALL REQUEST (19) 8 lci 10
From(14): 31250000000101 To(14): 31109090096101
Facilities: (0)
Cannot route call
Serial0 (704763372): X25 I P6 CLEAR REQUEST (5) 8 lci 10 cause 19 diag 67
Serial0 (704763839): X25 O P6 CLEAR CONFIRMATION (3) 8 lci 10
For each event, the first field identifies the interface on which the activity
occurred, the second field indicates the time between packets (in milliseconds),
and the third field indicates that it was an X.25 event. The fourth field indicates
whether the X.25 packet was input (I) or output (O). The fifth field is the state of
virtual circuit as defined in the X.25 standard.
The sixth field is the type of X.25 packet that triggered the event, and the
seventh field (in parentheses) gives the total length of the X.25 packet in bytes.
The eighth field is the window modulus. The ninth field (labeled lci) shows the
virtual circuit number. The tenth field (labeled cause) gives any cause code, and
the eleventh field (labeled diag) gives any diagnostic code. Cause and diagnostic
codes are not present for all messages.
For Call Request and Call Connected packets, the router shows additional
information on separate lines. The From field shows the calling X.121 address
and the To field shows the called X.121 address. The number in parentheses after
the field name—(14) for example—specifies the number of digits in the address.
The Facilities field indicates the length (in bytes) of the requested facilities and
the facilities contents.

Configuring CMNS Routing Support
The DECbrouter 90 support of Connection-Mode Network Service (CMNS)
provides a mechanism through which local X.25 switching can be extended to
different media (for example, Ethernet) by using OSI-based NSAP addresses.
This implementation essentially runs X.25 (packet level) over LLC2 (frame level)
to facilitate the extension of X.25 to other media. Digital’s CMNS implementation
supports services defined in ISO Standards 8208 (packet level) and 8802-2 (frame
level).
In addition, the DECbrouter 90 CMNS implementation allows LAN-based OSI
resources, such as a DTE host and a Sun workstation, to be interconnected
through the router’s LAN interfaces and to a remote OSI-based DTE through a
WAN interface (using, for example, an X.25 PSN).
Note
CMNS is implicitly enabled whenever an X.25 ENCAPSULATION
interface subcommand is included with a serial-interface configuration.
All local mapping is performed by statically mapping MAC addresses to NSAP
addresses and X.121 addresses to NSAP addresses.

9–42 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring CMNS Routing Support
Implementing CMNS routing on the DECbrouter 90 involves the following basic
steps:
1. Enable CMNS on an interface.
2. Map NSAP addresses to a MAC-address or X.121 address.
The discussions that follow detail commands used to perform these steps and
provide example configurations illustrating CMNS-based routing.

Enabling CMNS
To enable CMNS on a nonserial interface, use the CMNS ENABLE interface
subcommand. The command syntax is as follows:
cmns enable
no cmns enable
After executing this command, all the X.25-related interface subcommands are
made available on the LAN interfaces (Ethernet and others), as well as on serial
interfaces. The no version disables this feature.

Specifying CMNS Address Mappings
After enabling CMNS on a nonserial interface (or specifying X.25 encapsulation
on a serial interface), you must use the X25 MAP CMNS interface subcommand
to map NSAP addresses to either MAC-layer addresses or X.121 addresses,
depending on the application. The syntax for this command is:
x25 map cmns NSAP MAC-address
no x25 map cmns NSAP MAC-address
x25 map cmns NSAP [X.121-address]
no x25 map cmns NSAP [X.121-address]
The NSAP, MAC-address, and X.121-address arguments specify the NSAP
address-to-MAC address or NSAP address-to-X.121 address mappings. The
argument NSAP can be either the actual DTE NSAP address or the NSAP prefix
of the NSAP address. The NSAP prefix is sufficient for a best match to route a
call.
Note
For CMNS support over dedicated serial links (such as leased lines), an
X.121 address is not needed, but can be optionally included. You must
specify the X.121 address for CMNS connections over a packet-switched
network, and you must specify a MAC address for CMNS connections over
an Ethernet.
To retract a mapping, use the NO X25 MAP CMNS interface subcommand with
the appropriate address arguments.

Configuring Packet-Switched Software 9–43

Configuring Packet-Switched Software
Configuring CMNS Routing Support
Example Address Mappings
The following examples illustrate enabling CMNS and configuring X.121 and
MAC-address mappings:
interface ethernet 0
cmns enable
x25 map cmns 38.8261.1000.0150.1000.17 0000.0c00.ff89
! Above maps NSAP to MAC-address on Ethernet0
!
interface serial 0
encapsulation x25
x25 map cmns 38.8261.1000.0150.1000.18 3110451
! Above maps NSAP to X.121-address on Serial0
! assuming the link is over a PDN
!
interface serial 1
encapsulation x25
x25 map cmns 38.8261.1000.0150.1000.20
! Above specifies cmns support for Serial1
! assuming that the link is over a leased line

CMNS Configuration Examples
The following two examples illustrate common CMNS implementations for
switching traffic over different media. The first example depicts switching CMNS
over a packet-switched public data network (PDN); the second example illustrates
switching CMNS over a leased line. These applications are quite similar; there
are subtle differences in the use of the X25 MAP CMNS command.

Example 1: Switching CMNS over a PDN
Figure 9–8 illustrates the general network topology for a CMNS switching
application where calls are being made between resources on opposite sides of
a remote link to Host A and Host B, with a PDN providing the connection.

9–44 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring CMNS Routing Support
Figure 9–8 Example Network Topology for Switching CMNS over a PDN
Host A
MAC address: 0800.4e02.2abc
NSAP-address:
38.8261.1800.0150.0010.0000.17

Ethernet

Serial X.121 address: 4085551234
Ethernet0 MAC address: 0000.0c00.ff89

DECbrouter 90
C2
E0

DECbrouter 90
C1
S1

Serial X.121 address: 2095551000
Ethernet0 MAC address: 0000.0c00.1309

PDN

Host B
MAC address: 0800.4e02.1f9f
NSAP-address:
38.8261.1700.0150.0029.8431.02

E = Ethernet
S = Serial

S1047a

Ethernet

The following configuration listing allows resources on either side of the PDN to
call Host A or Host B. This configuration allows traffic intended for the remote
NSAP address specified in the X25 MAP CMNS commands (for the serial ports)
to be switched through the serial interface for which CMNS is configured.

Configuring Packet-Switched Software 9–45

Configuring Packet-Switched Software
Configuring CMNS Routing Support
The CMNS-related configuration for Router C2 in Figure 9–8 would be as follows:
! This configuration specifies that any traffic from any other
! interface intended for any NSAP address with NSAP prefix 38.8261.17
! will be switched to MAC address 0800.4e02.1f9f
! through Token Ring 0
!
interface ethernet 0
cmns enable
x25 map cmns 38.8261.17 0800.4e02.1f9f
!
! This configuration specifies that traffic from any other interface
! on DECbrouter 90 C2 that is intended for any NSAP address with
! NSAP-prefix 38.8261.18 will be switched to
! X.121 address 2095551000 through Serial 0
!
interface serial 0
encapsulation x25
x25 address 4085551234
x25 map cmns 38.8261.18 2095551000
The CMNS-related configuration for Router C1 in Figure 9–8 would be as follows:
! This configuration specifies that any traffic from any other
! interface intended for any NSAP address with NSAP 38.8261.18
! will be switched to MAC address 0800.4e02.2abc through Ethernet 0
!
interface ethernet 0
cmns enable
x25 map cmns 38.8261.18 0800.4e02.2abc
!
! This configuration specifies that traffic from any other interface
! on DECbrouter 90 C1 that is intended for any NSAP address with
! NSAP-prefix 38.8261.17 will be switched to X.121 address
! 4085551234 through Serial 1
!
interface serial 1
encapsulation x25
x25 address 2095551000
x25 map cmns 38.8261.17 4085551234

Example 2: Switching CMNS over Leased Lines
Figure 9–9 illustrates the general network topology for a CMNS switching
application where calls are being made by resources on opposite sides of a remote
link to Host B and Host C with a dedicated leased line providing the connection.
The following configuration listing allows resources on either side of the leased
line to call Host B or Host C. This configuration allows traffic intended for the
remote NSAP address specified in the X25 MAP CMNS commands (for the serial
ports) to be switched through the serial interface for which CMNS is configured.

9–46 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring CMNS Routing Support
Figure 9–9 Example Network Topology for Switching CMNS over a Leased Line
Host C
MAC address: 0800.4e02.123f
NSAP-address:
38.8261.2000.0150.0555.1212.07

Ethernet
Serial X.25 address: 00002
Ethernet0 MAC address: 0000.0c00.ee01

E0
DECbrouter 90
C4
E0

S0
S1

DECbrouter 90
C3

Private X.25 Network

Host B
MAC address: 0800.4e02.bcd0
NSAP-address:
38.8261.2100.0150.0688.4543.01

E = Ethernet
S = Serial

S1048a

Serial X.25 address: 00001
Ethernet0 MAC address: 0000.0c00.ab01

Ethernet

A key difference for this configuration in comparison with Example 1 is that with
no PDN, the specification of an X.121 address in the X25 MAP CMNS command
is not necessary. The specification of an X.25 address also is not needed, but is
included for symmetry with Example 1.

Configuring Packet-Switched Software 9–47

Configuring Packet-Switched Software
Configuring CMNS Routing Support
The CMNS-related configuration for Router C4 in Figure 9–9 would be as follows:
! This configuration specifies that any traffic from any other
! interface intended for any NSAP address with NSAP 38.8261.21
! will be switched to MAC address 0800.4e02.bcd0 through Token Ring 0
!
interface ethernet 0
cmns enable
x25 map cmns 38.8261.21 0800.4e02.bcd0
!
! This configuration specifies that traffic from any other interface
! on DECbrouter 90 C4 that is intended for any NSAP address with
! NSAP-prefix 38.8261.20 will be switched through Serial 0
!
interface serial 0
encapsulation x25
x25 address 00002
x25 map cmns 38.8261.20
The CMNS-related configuration for Router C3 in Figure 9–9 would be as follows:
! This configuration specifies that any traffic from any other
! interface intended for any NSAP address with NSAP 38.8261.20
! will be switched to MAC address 0800.4e02.123f through Ethernet 0
!
interface ethernet 0
cmns enable
x25 map cmns 38.8261.20 0800.4e02.123f
!
! This configuration specifies that traffic from any other interface
! on DECbrouter 90 C3 that is intended for any NSAP address with
! NSAP-prefix 38.8261.21 will be switched through Serial 1
!
interface serial 1
encapsulation x25
x25 address 00001
x25 map cmns 38.8261.21

Monitoring CMNS Traffic Activity
To display information pertaining to CMNS traffic activity, use the SHOW CMNS
EXEC command. The command syntax is as follows:
show cmns interface-name
The following is an example of the output of SHOW CMNS INTERFACE:
Ethernet 0 is up, line protocol is up
CMNS protocol processing disabled
This example indicates that CMNS is disabled on Ethernet 0.
The following display sample illustrates SHOW CMNS displays for a serial
interface.
Serial 0 is down, line protocol is down
X25 address 222222, state R1, modulo 8, idle 0, timer 0, nvc 1
Window size: input 2, output 2, Packet size: input 1024, output 1024
Timers: T10 60 T11 180 T12 60 T13 60 TH 0
Channels: Incoming 1-1024 Two-way 1-1024 Outgoing 1-1024
RESTARTs 0/0 CALLs 0+0/0+0/0+0 DIAGs 0/0

9–48 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring CMNS Routing Support
Refer to "Monitoring X.25 Level 3 Operations" earlier in this provided in the
preceding display.
The following display illustrates CMNS-related information presented on an
Ethernet display for SHOW CMNS:
Ethernet 0 is up, line protocol is up
Hardware address is 0000.0c01.1515 (bia 0000.0c01.1515), state R1
Modulo 8, idle 0, timer 0, nvc 1
Window size: input 2, output 2, Packet size: input 128, output 128
Timer: TH 0
Channels: Incoming 1-1024 Two-way 1-1024 Outgoing 1-1024
RESTARTs 0/0 CALLs 0+0/0+0/0+0 DIAGs 0/0\
•

The address field indicates the Hardware address (DTE address of the
interface).

•

The state field indicates the state of the interface. R1 is the normal ready
state (this should always be R1).

•

The Modulo field displays the modulo value, which determines the sequence
numbering scheme used.

•

The idle field shows the number of minutes the router waits before closing
idle virtual circuits.

•

The timer field shows the value of the interface timer and should always be
zero.

•

The nvc field displays the maximum number of simultaneous virtual circuits
permitted to the and from a single host.

•

The Window size and Packet size fields show the default window and packet
size for the interface. Each virtual circuit can override these values using
facilities specified with the X25 FACILITY subcommand.

•

The timer field indicates the value of timer TH is for the X.25 hold timer for
delayed acknowledgment.

•

The Channels field displays the channel sequence range for this interface per
LLC2 connection.

On the last line, packet statistics for the interface are displayed which use the
following format:
•
•
•

RESTARTs—Restarts sent/received
CALLS—Successful calls+failed calls/calls sent+calls failed/calls received+calls

failed

DIAGs—-Diagnostic messages sent+received.

Monitoring CMNS with LLC2 Parameters
There is an addendum to the SHOW LLC command in the case of CMNS calls;
for example, an LLC2 connection provides the following information:
LLC2 Connections to:
Ethernet0 DTE=0800.4E02.1F9F,000000000000 SAP=7E/7E, State=NORMAL
V(S)=2, V(R)=3, Last N(R)=2, Local window=7, Remote Window=7
akmax=3, n2=8, Next timer in 5196
xid-retry timer
0/60000 ack timer
0/1000
p timer
0/1000
idle timer 5196/10000
rej timer
0/3200
busy timer
0/9600
akdelay timer
0/3200
Configuring Packet-Switched Software 9–49

Configuring Packet-Switched Software
Configuring CMNS Routing Support
CMNS Connections to:
Address 0800.4E02.1F9F via Ethernet0
Protocol is up
Interface Type X25-DCE RESTARTS 0/1
Timers: T10 60 T11 180 T12 60 T13 60
The general LLC2-related information in the preceding display is documented
in the DECbrouter 90 Configuration and Reference, Volume 3. The following
information defines fields in the CMNS Connections to: portion of the display.
On the first line, the Address field is the Remote DTE address that connected to
via the LAN interface (in this example, Ethernet0).
On the second line, Protocol is up indicates that an existing LLC2 connection
exists with the remote DTE and has passed X.25 initialization (Restart
negotiation) of that LLC2 connection. Therefore, the link is ready for any
incoming/outgoing call request on this LLC2 connection.
On the third line, the Interface Type field indicates the type of this LLC2
connection. Options are X25-DCE, X25-DTE or X25-DXE. The RESTARTS field
represents the number of restarts sent/received on this LLC2 connection.
On the last line, Timers shows the value for the Request packet timers for this
LLC2 connection (T10 through T13 for a DCE interface type; T20 through T23 for
a DTE interface type).
Displaying CMNS Virtual Circuit Parameters and Statistics
When the protocol type used for the connection is CMNS, the display generated
with SHOW X25 VC differs slightly from the display outlined in the preceding
description.
A sample display output follows that depicts two complementary interfaces, both
running CMNS, providing transport of CMNS traffic to each other:
LCI: 1, State: P4, Interface: Serial1
Started 0:23:00, last input never, output never
Connected to CMNS [37.1111] <--> 313131 via Ethernet0 LCN 4095
to 0000.0c01.487d
Window size input: 6, output: 6
Packet size input: 1024, output: 1024
PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0 RNR: FALSE
Retransmits: 0 Timer (secs): 0 Reassembly (bytes): 0
Held Fragments/Packets: 0/0
Bytes 0/0 Packets 0/0 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
--More-LCI: 4095, State: P4, Interface: Ethernet0
Started 0:23:01, last input never, output never
Connected to CMNS [36.3030.3030.3030.30] <--> 0000.0c01.487d
via Serial1 LCN 1to 313131
Window size input: 6, output: 6
Packet size input: 1024, output: 1024
PS: 0 PR: 0 ACK: 0 Remote PR: 0 RCNT: 0 RNR: FALSE
Retransmits: 0 Timer (secs): 0 Reassembly (bytes): 0
Held Fragments/Packets: 0/0
Bytes 0/0 Packets 0/0 Resets 0/0 RNRs 0/0 REJs 0/0 INTs 0/0
The following display fields differ for CMNS virtual circuits:
•

On the first line, the LCI field displays the virtual circuit number; range is
1 to 4095. The State field displays the state of the virtual circuit (which is
independent of the states of other virtual circuits); P4 indicates the interface
is in the data transfer state. (See the CCITT X.25 recommendation for a
description of virtual circuit states.) The Interface field shows the interface

9–50 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring CMNS Routing Support
used for the virtual circuit. With CMNS, this can indicate Ethernet as well
as Serial.
•

On the third line, the Connected to field shows in brackets the NSAP address
for the device at the indicated X.121 address. For Serial1, it also indicates
the logical channel number (LCN) used (1 to 4095) and the MAC address of the
node to which the interface is connected.

Debugging CMNS
When installing a link on which CMNS is to be used, you can use the EXEC
command DEBUG with different keywords as follows:
debug x25
Enables the monitoring of all X.25 traffic, including CMNS-based traffic.
debug x25-events
Enables the monitoring of all X.25 traffic, but does not display information
about X.25 data or acknowledgment packets.
debug x25-vc number
Allows you to watch the specified port number with a virtual circuit using the
DEBUG X25 and DEBUG X25-EVENTS commands.

Configuring Frame Relay
This section describes frame relay configuration, the DECbrouter 90
implementation of frame relay, the protocols supported, and the hardware
needed to operate with a frame relay network.
Frame relay is described as an encapsulation method and is directed mainly
to users with large T1 network installations. The DECbrouter 90 supports the
two generally implemented specifications for frame relay logical management
interfaces (LMIs):
•

The Frame Relay Interface specification produced by Northern Telecom,
Digital Equipment Corporation, Stratacom, and Cisco Systems.

•

The ANSI-adopted frame relay specification,T1.617 Annex D.

The DECbrouter 90 implementation also conforms to the link access procedure
(LAP-D) defined by the CCITT under its I-series (ISDN) recommendation as
I122, "Framework for Additional Packet Model Bearer Services," and IETF
encapsulation in accordance with RFC 1294.
The DECbrouter 90 frame relay implementation currently supports routing on
AppleTalk, DECnet, IP, ISO CLNS, Novell IPX, VINES, and transparent bridging.
The DECbrouter 90 supports the local management interface (LMI), as specified
in the joint Frame Relay Interface specification. The LMI includes support for a
keepalive mechanism, a multicast group, and a status message.

Configuring Packet-Switched Software 9–51

Configuring Packet-Switched Software
Configuring Frame Relay
The keepalive mechanism provides an exchange of information between the
router and the switch to verify data is flowing. The multicast mechanism
provides the router with its local data link connection identifier (DLCI) and the
multicast DLCI. The status mechanism provides an ongoing status report on the
DLCIs known by the switch.
The DECbrouter 90 frame relay implementation sends congestion information
from frame relay to DECnet Phase IV and CLNS. This mechanism promotes
forward explicit congestion notification (FECN) and backward explicit congestion
notification (BECN) bits from the frame relay layer to upper layer protocols after
checking for the FECN or BECN bit on the incoming DLCI. Use this frame relay
congestion information to adjust the sending rates of end hosts. FECN/BECN-bit
promotion is enabled by default on any interface using frame relay encapsulation.
No configuration is required.
Note
When configuring IP routing over frame relay, you may need to
make adjustments to accommodate split-horizon effects. Refer to the
DECbrouter 90 Configuration and Reference, Volume 2 for details about
how the router handles possible split horizon conflicts. By default, split
horizon is disabled for frame relay networks.

Configuring the Hardware
The following hardware configuration is required for frame relay connections:
•

Each router connects directly to the frame relay switch.

•

Each router connects directly to a channel service unit/digital service unit
(CSU/DSU) first, and is connected to a remote frame relay switch.

The CSU/DSU converts V.35 or RS-449 signals to the properly coded T1
transmission signal for successful reception by the frame relay network.
Figure 9–10 illustrates the connections between the different components.
Figure 9–10 Frame Relay Physical Connection

V.35

CSU/DSU

4-wire T1

Public Frame
Relay Network

DECbrouter 90
Private Frame
Relay Network
S1049a

V.35

The frame relay interface actually consists of one physical connection between the
router and the switch that provides the service. This single physical connection
provides direct connectivity to each device on a network.

9–52 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Frame Relay
Specifying Frame Relay Encapsulation
Use the ENCAPSULATION FRAME-RELAY interface subcommand to specify
frame relay encapsulation on an interface. The DECbrouter 90 frame relay
feature supports IP encapsulation in conformance with RFC 1294, allowing
interoperability between multiple vendors. Use the IETF form of frame relay
encapsulation if your router is connected to another vendor’s equipment across a
frame relay network.
encapsulation frame-relay [ietf]
no encapsulation frame-relay [ietf]

Examples
These commands configure frame relay encapsulation on interface serial 1:
interface serial 1
encapsulation frame-relay
These commands configure frame relay encapsulation in conformance with RFC
1294 on interface serial 1. Use the ietf keyword if your communication server is
connected to another vendor’s equipment across a frame relay network.
interface serial 1
encapsulation frame-relay ietf

Enabling ANSI Frame Relay LMI
Use the FRAME-RELAY LMI-TYPE ANSI interface subcommand to specify use
of the ANSI LMI. The command syntax is as follows:
frame-relay lmi-type ANSI
no frame-relay lmi-type ANSI
This command specifies the exchange of LMI messages as defined by ANSI
standard T1.617.
The NO FRAME-RELAY LMI-TYPE ANSI returns the LMI type to the default
as defined by the Cisco/Stratacom/Northern Telecom/Digital specification. The
LMI type is set on a per-interface basis and is shown in the output of the SHOW
INTERFACE command.

Example
The following commands configure frame relay encapsulation on serial 0 and
specify use of the ANSI LMI:
interface serial 0
encapsulation frame-relay
frame-relay lmi-type ANSI

Configuring Packet-Switched Software 9–53

Configuring Packet-Switched Software
Configuring Frame Relay
Setting the Frame Relay Keepalive Timer
The FRAME-RELAY KEEPALIVE interface subcommand enables and disables
the LMI mechanism for serial lines using the frame relay encapsulation. The full
syntax of this command follows.
frame-relay keepalive seconds
no frame-relay keepalive
The argument seconds defines the keepalive interval. The interval must be set
and must match the interval set on the switch. The default keepalive interval is
ten seconds.
Note
The FRAME-RELAY KEEPALIVE and KEEPALIVE commands perform
the same function; both commands enable the keepalive sequence. The
keepalive sequence is part of the LMI protocol, so these commands also
control the enabling and disabling of the LMI.

Example
This command sets the keepalive timer on the router for a period that is two or
three seconds faster (shorter interval) than the interval set on the keepalive timer
of the frame relay switch. The difference in keepalive intervals ensures proper
synchronization between the router and the frame relay switch.
frame-relay keepalive 8

Mapping Between an Address and the DLCI
The FRAME-RELAY MAP subcommand defines the mapping between an address
and the DLCI used to connect to the address. There can be many DLCIs known
by a router that can send data to many different places, but all this data will
be multiplexed over the one physical link. The frame relay map tells the router
how to get from a specific protocol and address pair to the correct DLCI. The full
syntax of this command follows.
frame-relay map protocol protocol-address DLCI [broadcast] [ietf)]
no frame-relay map protocol protocol-address
The argument protocol is one of these keywords: ip, decnet, appletalk, xns,
novell, vines, or clns. The keyword is followed by the corresponding protocol
address and the DLCI number. The optional keyword broadcast specifies that
broadcasts should be forwarded to this address when multicast is not enabled.
See the section Defining a DLCI for Multicast for more information about the
multicast command.
The optional keyword ietf is used to select RFC 1294 encapsulation. If you are
using the ietf option, the argument protocol will be ip. Use the IETF form of the
map command if your router is connected to another vendor’s equipment across a
frame relay network.
The no version of the command deletes the entry.

9–54 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Frame Relay
Examples
This command maps IP address 131.108.123.1 to DLCI 100.
frame-relay map IP 131.108.123.1 100
The commands in the following example, which set IETF encapsulation at the
interface level, result in the same configuration as the commands used in the next
example, which set IETF on a per-DLCI basis. In this example, the keyword ietf
sets the default encapsulation method for all maps to IETF.
encapsulation frame-relay IETF
frame-relay map ip 131.108.123.2 48 broadcast
frame-relay map ip 131.108.123.3 49 broadcast
In the following configuration, IETF encapsulation is configured on a per-DLCI
basis. This configuration has the same result as the configuration in the previous
example.
encapsulation frame-relay
frame-relay map ip 131.108.123.2 48 broadcast ietf
frame-relay map ip 131.108.123.3 49 broadcast ietf
The following configuration provides backward compatibility and interoperability.
These functions are possible because of the flexibility provided by defining each
map entry separately.
encapsulation frame-relay
frame-relay map ip 131.108.123.2 48 broadcast ietf
!interoperability is provided by ietf encapsulation
frame-relay map ip 131.108.123.3 49 broadcast ietf
frame-relay map ip 131.108.123.7 58 broadcast
! this line allows the router to connect with a device
running an older version of software
frame-relay map DECNET 21.7 49 broadcast
Configure IETF based on map entries and protocol for more flexibility. Use this
method of configuration for backward compatibility and interoperability.

Configuring for ISO CLNS
This variation of the FRAME-RELAY MAP command is used for the ISO CLNS
protocol:
frame-relay map clns DLCI broadcast
This variation of the FRAME-RELAY MAP command is used for bridging:
frame-relay map bridge DLCI broadcast
In both these variations, there is no need to specify a protocol address; however,
the broadcast keyword is required for both.
The optional keyword broadcast specifies that broadcasts should be forwarded
to this address when the multicast is not enabled. The default is not to forward
broadcasts. The broadcast keyword is required for ISO CLNS and bridging
applications.
The NO FRAME-RELAY MAP subcommand with the appropriate arguments
deletes the entry.

Configuring Packet-Switched Software 9–55

Configuring Packet-Switched Software
Configuring Frame Relay

Examples
This command maps IP address 131.108.123.1 to DLCI 100. Broadcasts are not
forwarded.
frame-relay map IP 131.108.123.1 100
This command uses DLCI 144 for bridging.
frame-relay map bridge 144 broadcast
This command uses DLCI 125 for ISO CLNS routing.
frame-relay map clns 125 broadcast

Requesting Short Status Messages
The FRAME-RELAY SHORT-STATUS interface subcommand instructs the router
to request the short status message from the switch (see Version 2.3 of the joint
Frame Relay Interface Specification from Stratacom, August 9, 1990). The full
syntax of this command follows.
frame-relay short-status
no frame-relay short-status
The default is to request the full status message. Use the NO FRAME-RELAY
SHORT-STATUS command to override the default.

Example
This command returns the interface to the default state of requesting full status
messages.
no frame-relay short-status

Setting a Local DLCI
The FRAME-RELAY LOCAL-DLCI interface subcommand sets the source DLCI
for use when the LMI is not supported. If LMI is supported and the multicast
information element is present, the DECbrouter 90 sets its local DLCI based on
information provided via the LMI. The full syntax of this command follows.
frame-relay local-dlci number
no frame-relay local-dlci
The argument number is the local, or source, DLCI number. The NO FRAMERELAY LOCAL-DLCI command removes the DLCI number.
Note
The FRAME-RELAY LOCAL-DLCI command is provided mainly to allow
testing of the frame relay encapsulation in a setting where two routers
are connected back-to-back. This command is not required in a live frame
relay network.

9–56 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Frame Relay
Example
This command specifies 100 as the local DLCI.
frame-relay local-dlci 100

Defining a DLCI for Multicast
The FRAME-RELAY MULTICAST-DLCI interface subcommand defines a DLCI to
be used for multicasts. The full syntax of this command follows.
frame-relay multicast-dlci number
no frame-relay multicast-dlci
This command should be used only when the multicast facility is not supported.
Network transmissions (packets) sent to a multicast DLCI are delivered to
all routers defined as members of the multicast group. The multicast DLCI
is identified by the argument number. (Note that this is not the multicast
group number, which is an entirely different value.) The NO FRAME-RELAY
MULTICAST-DLCI command removes the multicast group.
Note
The FRAME-RELAY MULTICAST-DLCI command is provided mainly
to allow testing of the frame relay encapsulation in a setting where two
routers are connected back-to-back. This command is not required in a
live frame relay network.

Example
This command specifies 1022 as the multicast DLCI.
frame-relay multicast-dlci 1022

Frame Relay Configuration Examples
The following examples illustrate how to configure a router to support frame relay
connections.
Two Routers in Static Mode
The following examples illustrate how to configure two routers for static mode.

Example 1—First Router

interface serial 0
ip address 131.108.64.2 255.255.255.0
encapsulation frame-relay
frame-relay keepalive 10
frame-relay map ip 131.108.64.1 43

Configuring Packet-Switched Software 9–57

Configuring Packet-Switched Software
Configuring Frame Relay
Example 2—Second Router

interface serial 0
ip address 131.108.64.1 255.255.255.0
encapsulation frame-relay
frame-relay keepalive 10
frame-relay map ip 131.108.64.2 44
Routing DECnet Packets
The following example illustrates how to send all DECnet packets destined for
address 56.4 out on DLCI 101. In addition, any DECnet broadcasts for interface
serial 1 will be sent on the DLCI.

Example

interface serial 1
decnet routing 32.6
encapsulation frame-relay
frame-relay map decnet 56.4 101 broadcast
Routing Novell Packets
The following example illustrates how to send packets destined for Novell address
200.0000.0c00.7b21 out on DLCI 102.

Example

interface ethernet 0
novell network 2abc
!
interface serial 0
novell network 200
encapsulation frame-relay
frame-relay map novell 200.0000.0c00.7b21 102 broadcast
!

Monitoring Frame Relay
Use the EXEC commands in this section to monitor frame relay connections.
Monitoring the Frame Relay Interface
When using the frame relay encapsulation, the EXEC command SHOW
INTERFACE includes information on the multicast DLCI, the DLCI of the
interface, and the LMI DLCI used for the LMI.
The multicast DLCI and the local DLCI can be set using the FRAME-RELAY
MULTICAST-DLCI and the FRAME-RELAY LOCAL-DLCI subcommands, or
provided through the local management interface. The status information is
taken from the LMI, when active.
Enter this command at the EXEC prompt:
show interfaces [type unit]
Following is sample output.
9–58 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Frame Relay
router> show interfaces serial 1
Serial 1 is up, line protocol is up
Hardware type is MK5025
Internet address is 131.108.122.1, subnet mask is 255.255.255.0
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation FRAME-RELAY, loopback not set, keepalive set (10 sec)
multicast DLCI 1022, status defined, active
source DLCI
20, status defined, active
LMI DLCI 1023, LMI sent 10, LMI stat recvd 10, LMI upd recvd 2
Last input 7:21:29, output 0:00:37, output hang never
Output queue 0/100, 0 drops; input queue 0/75, 0 drops
Five minute input rate 0 bits/sec, 0 packets/sec
Five minute output rate 0 bits/sec, 0 packets/sec
47 packets input, 2656 bytes, 0 no buffer
Received 5 broadcasts, 0 runts, 0 giants
5 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 57 abort
518 packets output, 391205 bytes
0 output errors, 0 collisions, 0 interface resets, 0 restarts
1 carrier transitions
In this display, the multicast DLCI has been changed to 1022 with the FRAMERELAY MULTICAST-DLCI interface subcommand. The statistics for the LMI
are the number of status inquiry messages sent (LMI sent), the number of status
messages received (LMI recvd), and the number of status updates received (upd
recvd). See the Frame Relay Interface specification for additional explanations of
this output. Chapter 7 provides an explanation about the other fields seen in the
SHOW INTERFACES command.
Monitoring ANSI Frame Relay
Use the SHOW INTERFACE EXEC command to determine the LMI type
implemented. The following sample display illustrates the resulting display
from a SHOW INTERFACE command executed for a serial interface with the
ANSI LMI enabled.
router> show interface serial 1
Serial 1 is up, line protocol is up
Hardware is MK5025
Internet address is 131.108.121.1, subnet mask is 255.255.255.0
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation FRAME-RELAY, loopback not set, keepalive set
LMI DLCI
0, LMI sent 10, LMI stat recvd 10
LMI type is ANSI Annex D
Last input 0:00:00, output 0:00:00, output hang never
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
Five minute input rate 0 bits/sec, 1 packets/sec
Five minute output rate 1000 bits/sec, 1 packets/sec
261 packets input, 13212 bytes, 0 no buffer
Received 33 broadcasts, 0 runts, 0 giants
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
238 packets output, 14751 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets, 0 restarts
Two fields distinguish the use of the ANSI LMI from the default LMI. In the sixth
line of this display, the LMI DLCI field indicates a 0 value. If the LMI were set to
the default, the value would be 1023. In addition, the next line is added to the
display, stating that the LMI type is ANSI Annex D.

Configuring Packet-Switched Software 9–59

Configuring Packet-Switched Software
Configuring Frame Relay
Displaying Frame Relay Map Entries
Use this EXEC command to display the current frame relay map entries and
information about these connections:
show frame-relay map
Sample output follows.
Serial1: IP 131.108.122.2 dlci 10(0XA,0xA0), dynamic
status defined, active
The display lists the interface, the protocol, the protocol address, and the DLCI
being used to reach this address. If the optional broadcast keyword was entered
for a static map entry, this also will be shown.
The DLCI is displayed in three forms. For example, if the DLCI is 10, the
representations would be 10(0xA,0xA0). The displays show the decimal value,
the hexadecimal value, and the value of the DLCI as it would appear on the
wire. In addition, the display indicates whether this is a static or dynamic entry.
Status information for the DLCI is displayed if provided by the LMI.
For the CLNS protocol, the map has the following form:
Serial0: CLNS dlci 100(0X64,1840), static, broadcast, BW = 64000
status defined, active
Serial0: CLNS dlci 102(0X66,1860), static, broadcast, BW = 64000
status defined, active
Displaying Global Frame Relay Statistics
Use the SHOW FRAME-RELAY TRAFFIC command to display global frame relay
statistics. Enter this command at the EXEC prompt:
show frame-relay traffic
Sample output follows.
router> show frame-relay traffic
Frame Relay statistics:
ARP requests sent 14, ARP replies sent 0
ARP request recvd 0, ARP replies recvd 10
LMI sent 10, LMI stat recvd 10, LMI upd recvd 2, Multicast sent 48
Statistics for all frame relay interfaces in the router also are included in this
display.

9–60 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Frame Relay
Debugging Frame Relay
Use the EXEC commands described in this section to troubleshoot and monitor
activity on the interface configured for frame relay. For each DEBUG command,
there is a corresponding UNDEBUG command that turns messaging off.
debug frame-relay-events
Enables logging of key events in the transmission or receipt of packets
encapsulated using frame relay.
debug frame-relay-lmi
Enables logging of information on the local management interface packets
exchanged between the router and the frame relay service provider.
debug frame-relay-packet
Displays all packets being sent out on the frame relay network. The display
identifies the output interface, the protocol identifier, and the size of the
packet being sent.

Configuring Switched Multimegabit Data Services (SMDS)
The switched multimegabit data service (SMDS) is a wide-area networking
service offered by the regional bell operating companies (RBOCs) and other
telephone service carriers such as AT&T and MCI/Sprint. The SMDS protocol
is based on cell relay technology as defined in the Bellcore Technical advisories,
which is in turn based on the IEEE 802.6 Standard (also called the distributed
queue dual bus (DQDB) metropolitan area network media access control
protocol). For technical references, please see the bibliography in the "References
and Recommended Readings" list at the end of this publication.
The DECbrouter 90 provides an interface to an SMDS network using DS1
transmission facilities at the rate of 1.544 Mbps. Connection to the network is
made through a device called an SDSU—an SMDS CSU/DSU (Channel Service
Unit/Digital Service Unit) developed jointly by Cisco Systems and Kentrox. The
SDSU attaches to the DECbrouter 90 through an RS-449 connection. On the
other side, the SDSU terminates a DS1 line.

Configuring Packet-Switched Software 9–61

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
The DECbrouter 90 implementation of SMDS supports the IP, DECnet,
AppleTalk, XNS, Novell IPX, Ungermann-Bass Net/One, and OSI internetworking
protocols. IP routing is fully dynamic; that is, the routing tables are determined
and updated dynamically. Routing of the other supported protocols requires that
you establish a static routing table of SMDS neighbors in a user group. Once this
is set up, all interconnected routers provide dynamic routing.
This section describes the DECbrouter 90 implementation of SMDS and how to
configure, maintain, and debug SMDS.
Note
When configuring IP routing over SMDS, you may need to make
adjustments to accommodate split-horizon effects. Refer to the
DECbrouter 90 Configuration and Reference, Volume 2 for details
about how the DECbrouter 90 handles possible split-horizon conflicts. By
default, split horizon is disabled for SMDS networks.

Special SMDS Requirements
You need the following hardware, equipment, and special software to configure
the SMDS implementation serial port of the DECbrouter 90.
•

RS-449 transition cable

•

The SDSU device

Configuring SMDS
Follow these steps to configure SMDS service on the router:
1. Determine the protocols you will be running over SMDS. Obtain from the
service provider the group addresses that you will need to support those
protocols.
2. Obtain the SMDS hardware (individual) address from the service provider
for each router that will interface directly into the SMDS network (that is,
customer premises equipment).
Note
You also will need to know the addresses of the other routers with which
you will be communicating to set up the static routing tables. Note that
static mapping is needed only for protocols other than IP or CLNS. For
IP and CLNS, the routing is fully dynamic. (For more details, see related
routing chapters in this manual.)

3. Configure the desired serial interface with SMDS encapsulation.
4. Set up the static map for the desired protocols using the SMDS STATIC-MAP
command.
5. Set up the multicast map for the desired protocols using the SMDS
MULTICAST command.

9–62 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
Using SMDS Addresses
All addresses for SMDS service are assigned by the service provider and can be
assigned to individuals and groups.
A group address (also defined as a multicast address) is entered in the SMDS
configuration software using an E1 prefix. A C1 prefix is used to specify
individual addresses. The software expects the addresses to be entered in a
slightly modified E.164 format. E.164 format is 64 bits. The first four bits are
type code followed by 10 BCD digits padded to the full 60 bits with ones.
An example of an E.164 address follows.
C14155561313FFFF
Note
To simplify the addresses, the full E.164 address is not required. The
trailing FFFFs are not needed. They are not displayed, and it is not
necessary to type them when entering an address.
The addresses can be entered with periods similar to Ethernet-style notation, or
simply as a string of digits.
An example of an individual address entered in Ethernet-style notation looks like
this:
C141.5555.1212
An example of a group address looks like this:
E18009999999

Enabling SMDS
Enter the ENCAPSULATION SMDS interface subcommand to enable SMDS
service on the desired interface:
encapsulation smds
The interface to which this command applies must be a serial interface. All
subsequent SMDS configuration commands only apply to an interface with
encapsulation SMDS.

Example
Following is an example of the commands you use to configure the SMDS service
on interface serial 0:
!
interface serial 0
encapsulation smds

Configuring Packet-Switched Software 9–63

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
Note
The maximum packet size allowed in the SMDS specifications (TA-772) is
9188. This is larger than what can be used by routers with most media.
Therefore, the MTU defaults to 1500 bytes to be consistent with Ethernet.
If a larger MTU is used, the MTU command must be used before the
ENCAPSULATION SMDS command is used.

Specifying the SMDS Address
Enter the SMDS ADDRESS interface subcommand to specify the SMDS
individual address for a particular interface. The format of the command follows.
smds address smds-address
no smds address smds-address
Enter an individual address provided by the SMDS service provider for the
argument smds-address. Enter the address as described earlier in this chapter in
the section Using SMDS Addresses. This address is protocol-independent.
Enter the NO SMDS ADDRESS command to remove the address from the
configuration file.
There is no default for this command.

Example
The following example shows how to specify an individual address.
!
interface serial 0
smds address C141.5797.1313
!
Note
If bridging is enabled on any interface, the SMDS address is erased and
must be reentered.

Enabling the Address Resolution Protocol
Enter the SMDS ENABLE-ARP interface subcommand to enable the address
resolution protocol (ARP). The full syntax of this command follows.
smds enable-arp
no smds enable-arp
The multicast address for ARP must be set before this command is issued.
By default, ARP is not enabled. Once ARP has been enabled, use the NO SMDS
ENABLE-ARP command to return the line to the default state.

9–64 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
Defining a Static Map for an Individual Address
Enter the SMDS STATIC-MAP interface subcommand to configure a static
mapping between an individual SMDS address and a higher-level protocol
address. The full syntax of the command follows.
smds static-map protocol-type protocol-address smds-address
no smds static-map protocol-type protocol-address smds-address
Do not enter this command for broadcast or multicast addresses. For those
addresses, use the SMDS MULTICAST interface subcommand described in the
section Mapping to a Multicast Address later in this chapter.
Enter the name of the protocol for the protocol-type argument, followed with the
address (specified in the corresponding protocol address format) in place of the
protocol-address argument. Provide the SMDS address for the smds-address
argument to complete the mapping. You must use one of these keywords to define
the protocol type: ip, decnet, appletalk, xns, novell, or clns.
Use the NO SMDS STATIC-MAP command with the appropriate arguments to
remove the map.

Example
Following is an example of the SMDS STATIC-MAP command:
!
smds static-map XNS 111.00C0.2711.0123 C141.5688.1212
!
The command will map XNS address 111.00C0.2711.0123 to the individual SMDS
address C141.5688.1212.
Mapping to a Multicast Address
Enter the SMDS MULTICAST interface subcommand to map an SMDS group
address to a broadcast or multicast address used by higher-level protocols. The
full syntax of the command follows.
smds multicast protocol-type smds-address
no smds multicast protocol-type smds-address
Enter the name of the protocol for the protocol-type argument and follow with the
SMDS address to answer the smds-address argument to complete the mapping.
You can use these keywords to define the protocol type:
•

ip—IP

•

arp—ARP

•

decnet—DECnet

•

decnet_router—DECnet multicast address for all routers

•

decnet_node—DECnet multicast address for all end systems

•

appletalk—AppleTalk

•

aarp—AppleTalk ARP address

•

xns—XNS

•

novell—Novell IPX
Configuring Packet-Switched Software 9–65

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
•

clns—ISO CLNS

•

clns_is—Multicast address for all CLNS Intermediate Systems

•

clns_es—Multicast address for all CLNS End Systems

Since SMDS does not incorporate broadcast addressing, a group address for a
particular protocol must be defined to serve the broadcast function. There is no
default for this command.
Use the NO SMDS MULTICAST command with the appropriate arguments to
remove a multicast address.

Example
Following is an example of the SMDS MULTICAST command:
!
smds multicast IP E180.0999.9999
!
The command maps the IP broadcast address to the SMDS group address
E180.0999.9999.
Enabling the AT&T SMDS Service
The DECbrouter 90 implementation of SMDS includes a configuration option
that allows you to enable or disable the router’s ability to interface to an AT&T
SMDS switch that implements AT&T’s SMDS d15-mode. Please consult with
your service provider to find out whether this command is needed.
Use the SMDS D15-MODE interface subcommand in order to operate with an
AT&T SMDS switch that implements the AT&T d15-mode packet structure. The
command syntax follows.
smds d15 mode
no smds d15-mode
When this switch is disabled using the NO SMDS D15-MODE specification, the
router will use AT&T’s d11 packet structure.
When this switch is enabled, the router will use AT&T d15 packet structure. It
should be off for systems that have not been upgraded.
Use the NO SMDS D15-MODE command to turn this function off. By default, the
function is on.

Configuring Specific Protocols
An SMDS network can be thought of in much in the same way as an X25 cloud.
The premises equipment, in this case a router, represents the edge of the cloud.
The service provider enables communication across the cloud. However, proper
configuration is needed for communication to occur. This configuration will differ
between protocol families.
One major difference between protocol families is dynamic versus static routing
among the routers (called remote peers) on the periphery of the cloud. For IP and
CLNS, routing across the SMDS cloud is fully dynamic. No action on the user’s
part is needed for mapping of higher-level protocol addresses to SMDS addresses
to occur. For the other supported protocols, you must make a static entry for each

9–66 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
of the other neighbors. This entry provides a router with the information that it
needs to communicate with all other neighbor routers.
Up until now, this discussion has centered on the peer routers. What about all of
the end nodes and routers behind the SMDS router? The static entries only need
to be made for those routers that are SMDS remote peers. Nothing additional
needs to be done in order to communicate with other nodes behind the peer
routers.
Some protocol families need separate definitions for associated subprotocols. The
next sections illustrates how to implement these kind of configurations. See
Table 9–8 for a list of protocol families and the multicasts that are needed.
Table 9–8 Protocol Families and Types of Multicasts Needed
Protocol Family

Multicasts Needed

IP, ARP

DECnet

DECNET, DECNET_NODE, DECNET_ROUTER

CLNS

CLNS, CLNS_ES,CLNS_IS

Novell

NOVELL

XNS

AppleTalk

APPLETALK,AARP

Configuring IP
Both IP and ARP should be configured with the SMDS MULTICAST command.
ARP should be enabled. The results of the ARP activity can be shown with the
SHOW ARP command. If desired, static ARP entries can be made by using this
command:
arp ip-address address smds
The argument ip-address is the IP address. The argument address is the SMDS
address. The keyword smds appended to the end of this command is required.
Configuring AppleTalk
Currently, dynamic address assignment does not work. Therefore, an AppleTalk
address must be assigned to the interface, and each remote router peer must
be listed with an SMDS STATIC-MAP command. The AppleTalk ARP (AARP)
multicast address must still be configured with the SMDS MULTICAST
command. ARP should be enabled.
Configuring XNS and Novell
For XNS and/or Novell, the multicast address must be configured.
For Novell, RIP Routing packets, SAP packets, NetBios Name Lookups, directed
broadcasts, and traffic to the helper addresses (if that helper address is a
broadcast address) will be sent to the SMDS Novell multicast address.
For XNS, only RIP, directed broadcasts, and helper traffic will be sent to the XNS
multicast address.
For XNS and/or Novell configurations, a static map entry must be made for each
remote peer.

Configuring Packet-Switched Software 9–67

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
Configuring CLNS
Multicasts must be configured for CLNS_ES and CLNS_IS. No static maps are
necessary. ESHs, ISHs, and Router Hellos are sent to the multicast address, and
neighbor entries are created automatically.

IP Fast Switching
SMDS fast switching of IP packets provides faster packet transfer on serial
links with speeds above 56K. Use fast switching if you use high-speed, packetswitched, datagram-based WAN technology (such as X.25 or frame relay) offered
by telephone companies.
Configuring Fast Switching
This section describes the commands to use to configure fast switching To
configure the interface, use the following command:
interface type unit
The argument type is the type of interface, and unit is the number of the
interface.
To configure the interface for SMDS encapsulation, use the following command:
encapsulation smds
Use the following command to configure the interface for fast switching:
ip route-cache

Example
In the following example, serial interface number 5 is configured for SMDS
encapsulation and fast switching of IP packets.
interface serial 5
encapsulation smds
ip route-cache
Debugging Fast Switching
The debug serial-interface debugging command prints only condensed SMDS
packet information. For more debugging information, use the serial-packet
debugging command. See Debugging the Serial Interface section in Chapter 7 of
this manual.

SMDS Configuration Examples
This section provides some examples of configurations to use as models for your
configuration files.
Typical Multiprotocol Configuration
Following is a typical interface configured for IP, DECnet, ISO CLNS, Novell,
XNS, and AppleTalk.

9–68 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)

Example
interface Serial 1
ip address 1.1.1.2 255.0.0.0
decnet cost 4
appletalk address 92.1
appletalk zone smds
clns router igrp FOO
novell net 1a
xns net 17
encapsulation SMDS
! smds configuration follows
smds address c120.1580.4721
no smds d15-mode
smds static-map APPLETALK 92.2 c120.1580.4592
smds static-map APPLETALK 92.3 c120.1580.4593
smds static-map APPLETALK 92.4 c120.1580.4594
smds static-map NOVELL 1a.0c00.0102.23ca c120.1580.4792
smds static-map XNS 17.0c00.0102.23ca c120.1580.4792
smds static-map NOVELL 1a.0c00.0102.23dd c120.1580.4728
smds static-map XNS 17.0c00.0102.23aa c120.1580.4727
smds multicast NOVELL e180.0999.9999
smds multicast XNS e180.0999.9999
smds multicast ARP e180.0999.9999
smds multicast IP e180.0999.9999
smds multicast APPLETALK e180.0999.9999
smds multicast AARP e180.0999.9999
smds multicast CLNS_IS e180.0999.9990
smds multicast CLNS_ES e180.0999.9990
smds multicast DECNET_ROUTER e180.0999.9992
smds multicast DECNET_NODE e180.0999.9992
smds enable-arp
Configuration with a Remote Peer on the Same Network
An example of a remote peer on the same SMDS network follows. Note that this
router does not have DECnet routing enabled.
Example
interface Serial 0
ip address 1.1.1.1 255.0.0.0
appletalk address 92.2
appletalk zone smds
clns router igrp FOO
novell net 1a
xns net 17
encapsulation SMDS
! smds configuration follows
smds address c120.1580.4792
no smds d15-mode
smds static-map APPLETALK 92.1 c120.1580.4721
smds static-map APPLETALK 92.3 c120.1580.4593
smds static-map APPLETALK 92.4 c120.1580.4594
smds static-map NOVELL 1a.0c00.0102.23cb c120.1580.4721
smds static-map XNS 17.0c00.0102.23cb c120.1580.4721
smds static-map NOVELL 1a.0c00.0102.23dd c120.1580.4728
smds static-map XNS 17.0c00.0102.23aa c120.1580.4727
smds multicast NOVELL e180.0999.9999
smds multicast XNS e180.0999.9999
smds multicast ARP e180.0999.9999
smds multicast IP e180.0999.9999
smds multicast APPLETALK e180.0999.9999
smds multicast AARP e180.0999.9999

Configuring Packet-Switched Software 9–69

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
smds multicast CLNS_IS e180.0999.9990
smds multicast CLNS_ES e180.0999.9990
smds enable-arp

Monitoring SMDS Service
Use the following EXEC commands to monitor the SMDS service.
Displaying SMDS Individual Addresses
Use the SHOW SMDS ADDRESSES command to display the individual addresses
and the interface that they are associated with. Enter this command at the EXEC
prompt:
show smds addresses
A sample display of the command output follows.
SMDS address - Serial0

c141.5555.1212

Displaying Mapped SMDS Addresses
Use the SHOW SMDS MAP command to display all SMDS addresses that are
mapped to higher-level protocol addresses. Enter this command at the EXEC
prompt:
show smds map
The display for this command includes all addresses entered with both the SMDS
STATIC-MAP and SMDS MULTICAST command.
A sample display of the command output follows.
Serial0: ARP maps to e180.0999.9999 multicast
Serial0: IP maps to e180.0999.9999 multicast
Serial0: XNS 1006.AA00.0400.0C55 maps to c141.5688.1212 static
Note
Trailing Fs are implied in displays showing the SMDS addresses.

Displaying SMDS Counters
Use the SHOW SMDS TRAFFIC command to display all the SMDS counters.
Enter this command at the EXEC prompt:
show smds traffic
A sample display of the command output follows.
0 Bad BA size errors
0 Bad Header extension errors
0 Invalid address errors
In the display:
•

The Bad BA size errors field lists the number of corrupted packets received
based on the expected Level 3 PDU buffer allocation size.

9–70 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Configuring Switched Multimegabit Data Services (SMDS)
•

The Bad Header extension errors field lists the number of invalid packets
received in which the header extension length did not match what was
expected in the Level 3 PDU.

•

The Invalid address errors field lists the number of packets passed that
were incorrectly sent to router. Both individual and multicast address errors
are included in this count.

Debugging SMDS
Use the following EXEC commands to debug the SMDS service. For each DEBUG
command, there is a corresponding UNDEBUG command that turns the messages
off.
debug arp
Use this command to see whether ARPs are being sent or received. This
command prints one line for each ARP sent or received.
debug serial-interface
Use this EXEC command to enable logging of SMDS events. This command
prints a one-line message for each packet that is sent. The packet size, packet
type, and SMDS source and destination addresses are printed. If a packet is
received with an incorrect destination address, it will be noted and counted.

Packet-Switched Software Global Configuration Command
Summary
Summaries of the global configuration commands relevant to each of the packetswitching technologies described in this chapter are collected in the listing that
follows. These commands are listed in alphabetical order, according to technology
type.

X.25 Global Configuration Command Summary
This section provides an alphabetically arranged summary of the X.25 global
configuration commands.
x25 bfe-decision {no | yes | ask}
Configures how or if the router will participate in making the decision to
enter emergency mode. When the router’s mode is set to decision (this mode
is set using the X25 BFE-EMERGENCY command described next), the type
of decision must be indicated by using the X25 BFE-DECISION command.
If the decision type is set to no (the default value), the router will not
participate in the decision to enter or leave emergency mode. If the decision
type is set to yes, the router will participate in entering emergency mode. If
the decision type is set to ask, the router will prompt the administrator to
use an EXEC command to place the router in and out of emergency mode.

Configuring Packet-Switched Software 9–71

Configuring Packet-Switched Software
Packet-Switched Software Global Configuration Command Summary
x25 bfe-emergency {never | always | decision}
Configures the circumstances under which the router will enter emergency
mode. The default keyword value is never. When set to never, the router
does not go into emergency mode. When set to always, the router enters
emergency mode when directed by the BFE. When set to decision the router
waits until it receives a diagnostic packet from the BFE device indicating that
an emergency mode window is open before it enters emergency mode.
x25 remote-red host-ip-address remote-black Blacker-Internet-address
Sets up the table that lists the BFE nodes to which the router will send
packets. The host-ip-address argument is the IP address of the host or a
router that the packets are being sent to. The Blacker-Internet-address
argument is the IP address of the remote Blacker front-end unit in front of
the host that the packet is being sent to.
[no] x25 route [# position]x121-pattern [cud pattern] interface interface-name
[no] x25 route [# position]x121-pattern [cud pattern] ip ip-address
[no] x25 route [# position]x121-pattern [cud pattern] alias interface-name
[no] x25 route [#position]x121-pattern [substitute-source rewrite-pattern]
[substitute-dest rewrite-pattern] [cud pattern] interface destination-interface
Inserts or removes an entry in the X.25 routing table. The x121-pattern
pattern parameter is the X.121 address of the called destination and is
required. The alias keyword permits a way for other X.121 addresses to be
treated as local. The substitute-source keyword allows substitution of the
calling address. The argument rewrite-pattern replaces the called or calling
X.121 address in routed X.25 packets.
[no] x25 routing
Enables or disables X.25 switching. X.25 calls will not be forwarded until
this command is issued. The command NO X25 ROUTING disables the
forwarding of X.25 calls.

9–72 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary

Packet-Switched Software Interface Subcommand Summary
Summaries of the interface subcommands relevant to each of the packet-switching
technologies described in this chapter are collected in the listing that follows.
These commands are listed in alphabetical order, according to technology type.
Interface subcommands are summarized for the following:
•

CMNS

•

Frame Relay

•

LAPB

•

SMDS

•

X.25

CMNS Interface Subcommand Summary
This section provides an alphabetical list of all the interface subcommands used
in the X.25 interface.
[no] cmns enable
Enables CMNS on a nonserial interface. After executing this command, all
the X.25-related interface subcommands are made available on the Ethernet
interface as well as on serial interfaces. The NO CMNS ENABLE command
disables CMNS for the interface.
[no] x25 map cmns NSAP MAC-address
[no] x25 map cmns NSAP [X.121-address]
After enabling CMNS on a nonserial interface (or specifying X.25
encapsulation on a serial interface), you must use the X25 MAP CMNS
interface subcommand to map NSAP addresses to either MAC-layer addresses
or X.121 addresses, depending on the application.
The NSAP, MAC-address, and X.121-address arguments specify the NSAP
address-to-X.121 address or NSAP address-to-MAC address mappings.
To retract a mapping, use the NO X25 MAP CMNS interface subcommand
with the appropriate address arguments.

Configuring Packet-Switched Software 9–73

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
Frame Relay Interface Subcommand Summary
Following is an alphabetically arranged summary of the frame relay interface
subcommands.
encapsulation frame-relay
Specifies frame relay encapsulation on a specific interface.
[no] frame-relay keepalive seconds
Enables and disables the LMI mechanism for serial lines using the frame
relay encapsulation.
[no] frame-relay local-dlci number
Sets the source DLCI for use when the LMI is not supported. If LMI is
supported and the multicast information element is present, the router sets
its local DLCI based on information provided via the LMI. The argument
number is the local, or source, DLCI number.
[no] frame-relay lmi-type ANSI
Specifies the exchange of local management interface messages as defined by
ANSI standard T1.617.
The no frame-relay lmi-type ANSI returns the LMI type to the default as
defined by the Cisco/Stratacom/Northern Telecom/Digital specification.
[no] frame-relay map protocol protocol-address DLCI [broadcast] [ietf]
Defines the mapping between an address and the DLCI used to connect to
the address. The frame relay map tells the router how to get from a specific
protocol and address pair to the correct DLCI. The argument protocol can
be one of these keywords: ip, decnet, appletalk, xns, novell, vines, clns.
The keyword is followed by the corresponding protocol address and the DLCI
number. The optional broadcast flag specifies that broadcasts should be
forwarded to this address when the multicast is not enabled. The default is
not to forward broadcasts.
The optional keyword ietf is used to select RFC 1294 encapsulation. If you
are using the ietf option, the argument protocol will be ip. Use the IETF
form of the map command if your router is connected to another vendor’s
equipment across a frame relay network.
The no version of the command deletes the entry.
[no] frame-relay map bridge DLCI broadcast
This variation of the FRAME-RELAY MAP command is used for bridging.

9–74 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary

[no] frame-relay map clns DLCI broadcast
This variation of the FRAME-RELAY MAP command is used for the ISO
CLNS protocol.
no frame-relay map
Deletes the frame relay map entry.
[no] frame-relay multicast-dlci number
Defines a DLCI to be used for multicasts and should only be used when the
multicast facility is not supported. Network transmissions (packets) sent
to a multicast DLCI are delivered to all routers defined as members of the
multicast group. The argument number identifies the multicast group.
[no] frame-relay short-status
Instructs the router to request the short status message from the switch (see
Version 2.3 of the joint Frame Relay Interface specification). The default is to
request the full status message.

LAPB Interface Subcommand Summary
This section provides an alphabetical list of all the interface subcommands used
in the LAPB interface.
encapsulation {lapb | lapb-dce}
Enables running datagrams of a single protocol over a serial interface using
the LAPB encapsulation. The keyword lapb sets DTE operation; the keyword
lapb-dce sets DCE operation. One end of the link must be DTE, and the
other must be DCE. By default, the single protocol is IP.
encapsulation {multi-lapb | multi-lapb-dce}
Enables use of multiple network protocols on the same line at the same time.
lapb k window-size
Specifies the maximum permissible number of outstanding frames, called the
window size. The argument window-size is a packet count from one to seven.
The default value is seven packets.

Configuring Packet-Switched Software 9–75

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
lapb n1 bits
Specifies the maximum number of bits a frame can hold, as indicated by the
n1 keyword. The argument bits is the number of bits from 1 through 12,000
and must be a multiple of eight. The default value is 12,000 bits (1500 bytes).
lapb n2 retries
Specifies the maximum number of times an acknowledgment frame can be
retransmitted. The argument retries is the retransmission count from 1
through 255. The default value is 20 retransmissions.
lapb protocol keyword
Enables configuration of other protocols over a serial interface using
LAPB encapsulation. Possible protocol keywords include ip, xns, decnet,
appletalk, vines, clns, novell, and apollo.
lapb t1 milliseconds
Sets the limit for the retransmission timer (the LAPB T1 parameter). The
argument milliseconds is the number of milliseconds from 1 through 64000.
The default value is 3,000 milliseconds.

SMDS Interface Subcommand Summary
This section provides an alphabetically arranged summary of the SMDS interface
subcommands. These commands must be preceded by an interface command.
arp ip-address address smds
Allows inclusion of static ARP entries. The argument ip-address is the IP
address. The argument address is the SMDS address. The keyword smds
appended to the end of this command is required.
encapsulation smds
Enables or disables SMDS on a particular interface. It should precede any
SMDS command. This command has no default.
ip route-cache
Configures an SMDS interface for fast switching.

9–76 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
[no] smds address smds-address
Sets or removes the SMDS individual address for a particular interface. The
argument smds-address is the individual address provided by the SMDS
service provider and is protocol independent. This command has no default.
[no] smds d15-mode
Allows for interoperation with an AT&T SMDS switch that implements
the AT&T d15-mode packet structure. When this feature is disabled using
the no smds d15-mode specification, the router will use AT&T’s d11-mode
implementation.
[no] smds enable-arp
Enables or disables ARP processing on a particular interface. The multicast
address for ARP must be set before this command is issued. Default is no
smds enable-arp.
[no] smds multicast protocol-type smds-group-address
Maps an SMDS group address to a broadcast or multicast address used by
higher-level protocols. This command has no default.
[no] smds static-map protocol-type protocol-address smds-address
Sets up a static mapping between an SMDS address and a higher-level
protocol address. This should not be used for broadcast addresses; for
broadcast addresses, use the SMDS MULTICAST command. This command
has no default.

X.25 Interface Subcommand Summary
This section provides an alphabetical list of all the interface subcommands used
in the X.25 interface.
encapsulation bfex25
This encapsulation provides a mapping from Class A IP addresses to the type
of X.121 addresses expected by the BFE encryption device.
encapsulation {ddnx25 | ddnx25-dce}
Causes the router to specify the standard service facility in the Call Request
packet, which notifies the PSNs to use standard service.

Configuring Packet-Switched Software 9–77

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
encapsulation hdh
Enables the HDH protocol.
encapsulation x25
Sets X.25 DTE operation.
encapsulation x25-dce
Sets X.25 DCE operation.
hdh {packet | message}
Enables router support for both the packet and message modes of HDH. The
packet keyword specifies the packet mode; the message keyword specifies the
message mode.
[no] x25 accept-reverse
Instructs the router to accept all reverse-charged calls. This behavior can also
be configured on a per-peer basis using the X25 MAP subcommand. The no
form of the command resets the default state.
x25 address X.121-address
Sets the X.121 address of a particular network interface. The address is
assigned by the X.25 network. The argument X.121-address is a variablelength X.121 address.
[no] x25 default protocol
Specifies or removes the protocol assumed by the CPT to interpret calls with
unknown Call User Data. The argument protocol sets the default protocol
and is either ip or pad.
x25 facility keyword argument
no x25 facility keyword argument
Overrides interface settings on a per-call basis.
The command enables X.25 facilities, which are sent between DTE and DCE
devices to negotiate certain link parameters.
The argument keyword specifies one of the following keywords, followed by
the required argument:

9–78 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
•

cug number—Specifies a closed user group number from 1 through 99 to
provide an extra measure of network security.

•

packetsize in-size out-size—Sets the size in bytes of input packets (in-size)
and output packets (out-size). Both values should be the same.

•

reverse—Reverses charges on all Call Request packets from the interface.

•

windowsize in-size out-size—Sets the packet count for input windows
(in-size) and output windows (out-size). Both values should be the same.

•

throughput in out—Sets the requested throughput values for input and
output throughput across the network.

•

rpoa name—Specifies the list of transit Recognized Private Operating
Agencies (RPOAs) to use in outgoing Call Request packets.

•

transit-delay number—-Specifies the transit delay value in milliseconds (0 to
65334) for mapping in outgoing calls for networks that support transit delay.
The NO X25 FACILITY command with the appropriate keyword and
argument removes the facility.

x25 hic circuit-number
Sets the highest incoming virtual circuit number. The argument circuitnumber is the circuit number from 1 through 4095. The default value is 0
(range disabled).
x25 hoc circuit-number
Sets the highest outgoing virtual circuit number. The argument circuitnumber is the circuit number from 1 through 4095. The default value is 0
(range disabled).
[no] x25 hold-queue queue-size
Defines the number of packets to be held until a virtual circuit is established.
The argument queue-size defines the number of packets. By default, this
number is zero. The no form without an argument removes this command
from the configuration file; the command with a queue size value of zero
returns the default.
[no] x25 hold-vc-timer minutes
Prevents overruns on X.25 switches for traffic through the VCs. The
argument minutes is the number of minutes to prevent calls to a previously
failed destination. Incoming calls still will be accepted.

Configuring Packet-Switched Software 9–79

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
x25 htc circuit-number
Sets the highest two-way channel (HTC). The argument circuit-number is a
circuit number from 1 through 4095. The default value is 1024.

[no] x25 idle minutes
Sets the period of inactivity once an SVC has been cleared. The argument
minutes is the number of minutes in the period. Calls both originated and
terminated by the router are cleared. The default value is 0 (zero), which
causes the router to keep the SVC open indefinitely. The no variation restores
this default.
[no] x25 ip-precedence
Enables or disables the ability to open a new virtual circuit based on the IP
type of service (TOS) field. By default, the DECbrouter 90 opens one virtual
circuit for each type of service.
x25 ips bytes
x25 ops bytes
Set the router packet size to match those of the network. The ips keyword
specifies the router input packet size, while the keyword ops specifies the
router output packet size. The argument bytes is a byte count in the range
of 128 through 1024. The default value is 128 bytes. Larger packet sizes
are better than smaller ones because smaller packets require more overhead
processing.
Note
Set the x25 ips and x25 ops keywords to the same value unless your
network supports asymmetry between input and output packets.

x25 lic circuit-number
Sets the lowest incoming virtual circuit number. The argument circuitnumber is a circuit number from 1 through 4095. The default value is 0
(range disabled).

9–80 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
[no] x25 linkrestart
Forces a packet-level restart when the link level is restarted and restarts
X.25 Level 2 (LAPB) when errors occur. This behavior is the default and
is necessary for networks that expect this behavior. The no form of the
command turns off the default.

x25 loc circuit-number
Sets the lowest outgoing virtual circuit number. The argument circuit-number
is the circuit number from 1 through 4095. The default value is 0 (range
disabled).
x25 ltc circuit-number
Sets the lowest two-way channel (LTC). The argument circuit-number is the
circuit number from 1 through 4095. The default value is one.
x25 map bridge X.121-address broadcast [options-keywords]
Configures support for bridging of X.25 frames. The command specifies
Internet-to-X.121 address mapping. The keyword bridge specifies bridging
over X.25. The argument X.121-address is the X.121 address. The keyword
broadcast is required for bridging X.25 frames. The argument optionskeywords represents services that can be added to this map.
[no] x25 map compressedtcp ip-address x.121-address [options]
Specifies a network protocol-to-X.121 address mapping such as Internet-toX.121 or DECnet-to-X.121. Refer to the description of the x25 map interface
subcommand for supported protocols. This version is required to make the
X.25 calls complete for compressed packets.
The argument ip-address is the IP address and x.121-address is the X.121
address. The options arguments are the same options as those for the x25
map command.
The Call User Data of compressed TCP calls is the single byte 0xd8.
The NO X25 MAP COMPRESSEDTCP disables TCP header compression for
the link.
[no] x25 map protocol-keyword protocol-address X.121-address [options]
Specifies a network protocol-to-X.121 address mapping such as Internet-toX.121 or DECnet-to-X.121. The argument protocol-keyword can be one of
these protocol types: ip, decnet, chaos, xns, novell, appletalk, vines,
apollo, pup, clns, bridge, cmns, and compressedtcp. The address
arguments specify the network protocol-to-X.121 mapping. The options
Configuring Packet-Switched Software 9–81

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
arguments add certain features to the mapping specified and can be any of
the following:
•

accept-reverse—Causes the router to accept incoming reverse-charged calls.
If this option is not present, the router clears reverse-charged calls.

•

cug number—Specifies a closed user group number (from 1 to 99) for the
mapping in the outgoing call.

•

modulo size—Specifies the maximum window size for this map. The
argument size permits windows of 8 or 128 on the same interface.

•

nuid username password—Specifies that a network ID facility be sent in the
outgoing call with the specified user name and password.

•

nvc count—Sets the number of virtual circuits (VCs) for this map/host. The
default count is the x25 nvc setting of the interface. A maximum number of
eight VCs can be configured for a single map/host.

•

packetsize in-size out-size—Specifies input packet size (in-size) and output
packet size (out-size) for the mapping in the outgoing call.

•

reverse—Specifies reverse charging for outgoing calls.

•

rpoa name—Specifies the list of transit Recognized Private Operating
Agencies (RPOAs) to use in outgoing Call Request packets for this x25 map
entry.

•

throughput in out—Requests the amount of bandwidth through the X.25
network.

•

transit-delay number—Specifies the transit delay value in milliseconds (0 to
65334) for mapping in outgoing calls for networks that support transit delay.

•

windowsize in-size out-size—Specifies input window size (in-size) and output
window size (out-size) for the mapping in the outgoing call.

x25 modulo modulus
Sets the modulus. The argument modulus is either 8 or 128. The default
value is eight. The value of the modulo parameter must agree with that of
the device on the other end of the X.25 link.
x25 nvc count
Specifies the maximum number of switched virtual circuits that can be open
simultaneously to one host. The argument count is a circuit count from 1 to
8; the default is 1.

9–82 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
[no] x25 pvc circuit protocol-keyword protocol-address [options]
Establishes or deletes permanent virtual circuits (PVCs). The argument
circuit is a virtual circuit channel number; it must be less than the lower
limit of the incoming call range in the virtual circuit channel sequence (set
using the lic keyword). The argument protocol-keyword can be one of the
supported protocol types: ip, decnet, chaos, xns, novell, appletalk, vines,
apollo, pup, and bridge. The argument protocol-address is that of the host
at the other end of the PVC.
The optional argument options can be one of the following:
•

packetsize in-size out-size—Specifies input packet size (in-size) and output
packet size (out-size) for the mapping in the outgoing call.

•

windowsize in-size out-size—Specifies input window size (in-size) and output
window size (out-size) for the mapping in the outgoing call.
Note
You must specify the required network protocol-to-X.121 address mapping
with an x25 map sub before you can set up a PVC.

x25 pvc pvc-number interface interface-name pvc-number [options]
Configures a PVC for a given interface. The argument pvc-number is the PVC
number that will be used on the local interface (as defined by the primary
interface command). The argument interface-name is the interface type and
unit number (serial 0, for example), as specified by the interface keywords.
The optional argument options can be one of the following:
•

packetsize in-size out-size—Specifies input packet size (in-size) and output
packet size (out-size) for the mapping in the outgoing call.

•

windowsize in-size out-size—Specifies input window size (in-size) and output
window size (out-size) for the mapping in the outgoing call.

[no] x25 rpoa name number
Specifies a list of transit RPOAs to use, referenced by name. The argument
name must be unique with respect to all other RPOA names. It is used in the
X25 FACILITY and X25 MAP interface subcommands. The argument number
is a number that is used to describe an RPOA.

Configuring Packet-Switched Software 9–83

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
[no] x25 suppress-called-address
Omits the called address in outgoing calls The suppress-called-address
keyword omits the called (destination) X.121 address in Call Request packets.
This option is required for networks that expect only subaddresses in the
called address field. The called address is sent by default. The no form resets
this subcommand to the default state.

[no] x25 suppress-calling-address
Omits the calling (source) X.121 address in Call Request packets. This option
is required for networks that expect only subaddresses in the calling address
field. The calling address is sent by default. The no form of the command
resets the default state.
x25 t10 seconds
Sets the limit for the Restart Request retransmission timer (T10) on DCE
devices. The argument seconds is a time value in seconds. The default value
is 60 seconds.
x25 t11 seconds
Sets the limit for the Call Request completion timer (T11) on DCE devices.
The argument seconds is a time value in seconds. The default value is 180
seconds.
x25 t12 second
Sets the limit for the Reset Request retransmission timer (T12) on DCE
devices. The argument seconds is a time value in seconds. The default value
is 60 seconds.
x25 t13 seconds
Sets the limit for the Clear Request retransmission timer (T13) on DCE
devices. The argument seconds is a time value in seconds. The default value
is 60 seconds.
x25 t20 seconds
Sets the limit for the Restart Request retransmission timer (T20) on DTE
devices. The argument seconds is a time value in seconds. The default is 180
seconds.

9–84 Configuring Packet-Switched Software

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
x25 t21 seconds
Sets the limit for the Call Request completion timer (T21) on DTE devices.
The argument seconds is a time value in seconds. The default value is 200
seconds.
x25 t22 seconds
Sets the limit for the Reset Request retransmission timer (T22) on DTE
devices. The argument seconds is a time value in seconds. The default value
is 180 seconds.

x25 t23 seconds
Sets the limit for the Clear Request retransmission timer (T23) on DTE
devices. The argument seconds is a time value in seconds. The default value
is 180 seconds.
x25 th delay
Instructs the router to send acknowledgment packets when it is not busy
sending other packets, even if the number of input packets has not reached
the win count, which improves line responsiveness at the expense of
bandwidth. The argument delay must be between zero and the input
window size. A value of one sends one Receiver Ready acknowledgment
per packet at all times. The default value is zero, which disables the delayed
acknowledgment strategy.
[no] x25 use-source-address
Updates the source address of outgoing calls forwarded over a specific
interface. The no variation prevents the update.
x25 win packets
x25 wout packets
Set the upper limits on the number of outstanding unacknowledged packets.
The win keyword specifies the upper limits of the number of outstanding
unacknowledged packets in the input window and determines how many
packets the router can receive before sending an X.25 acknowledgment.
The wout keyword specifies the upper limits of the number of outstanding
unacknowledged packets in the output window. The wout limit determines
how many sent packets can remain unacknowledged before the router uses a
hold queue.

Configuring Packet-Switched Software 9–85

Configuring Packet-Switched Software
Packet-Switched Software Interface Subcommand Summary
To maintain high bandwidth utilization, assign these limits the largest
number that the network allows. The argument packets is a packets count.
The packet count for win and wout can range from one to the window
modulus. The default value is two packets.
Note
Set win and wout to the same value unless your network supports
asymmetry between input and output window sizes.

X.25 EXEC Command Summary
This section provides an alphabetical list of X.25 EXEC commands.
bfe {enter | leave} interface-type unit
Implements Blacker emergency mode on an interface. The keyword options
are enter and leave, indicating whether the interface will go in or out of
emergency mode. The interface-type argument is the interface name, and unit
is the interface number. Use this command to enter or leave the emergency
mode of operation if your system is in emergency mode decision and decision
type ask.

9–86 Configuring Packet-Switched Software

Index
A
ACCESS-CLASS command, 4–39
Access control
terminal, 4–22
Access lists
assigning to DDR interfaces, 7–32
Accounting option, 7–6
Addresses
mappings, 9–8, 9–14
mapping to multicast, 9–65
PVC protocol, 9–11
suppress called, 9–31
suppress calling, 9–31
Angle bracket (>)
as system prompt, 2–7
ANSI frame relay
enabling, 9–53
monitoring, 9–59
ARP command
SMDS option, 9–68
AT&T SMDS service
enabling, 9–66

B
BACKUP DELAY command, 7–21
BACKUP INTERFACE command, 7–20
Backup line, 7–20
defining delay, 7–21
BACKUP LOAD command, 7–20
Bandwidth
setting interface, 8–9
BANDWIDTH command, 8–9
Banner
disabling, 4–40
enabling, 4–40
setting system, 4–2
suppressing display, 4–40
BANNER command, 4–2
Banner displays
order, 4–3
BANNER EXEC command, 4–3
BANNER INCOMING command, 4–3
Banner message
changeable banners, 4–2
displaying, 4–2

Banner message (cont’d)
EXEC process, 4–3
incoming on specific terminal line, 4–3
message-of-the-day, 4–2
on incoming connections, 4–3
suppressing, 4–40
BANNER MOTD command, 4–2
BFE
encryption, 9–35
BFE {enter | leave} command, 9–36, 9–86
BGP
support in router, 1–2
Blacker Emergency Mode, 9–35
encapsulation, 9–35
monitoring, 9–37
BOOT BUFFERSIZE command, 4–7
BOOT command, 2–14, 4–6
Boot commands
configuring multiple instances, 4–7
Boot file
configuration, 4–6
specifying buffer size, 4–7
BOOT HOST command, 4–7
Booting from Flash Memory
automatically, 4–16
manually, 4–17
Booting system software
using the Flash Memory card, 4–8
BOOT NETWORK command, 4–6
BOOT SYSTEM FLASH command, 4–16
Break key
function, 3–7
Bridging
X.25 frames, 9–34
Buffers
internal, message logging, 4–34
management parameters, 4–5
pool statistics, 6–2
setting, 4–5
setting size of, 4–6
setting system, 4–5
BUFFERS command, 4–5
BUFFERS HUGE SIZE command, 4–5
Buffer size
use for netbooting, 4–7

Index–1

Buffer sizing
dynamic, 4–5
Bypass mode
and FDDI optical bypass switch, 7–2

C
Called addresses
suppressing X.25, 9–31
translating X.25, 9–20
Calling address
suppressing X.25, 9–31
Call request
retransmission timer, 9–27
virtual circuit, 9–13
Call User Data
compressed TCP, 9–33
defined, 9–13
protocols and initial bytes, 9–13
Call user data field
virtual circuit, 9–13
CAP
carrier wait time, specifying, 7–26
CHAP
enabling on interface, 7–41
using, 7–41
CHAP AUTHENTICATION command, 7–41, 7–49
Character padding
changing, 3–8
setting, 3–8, 4–43
Character width
8-bit support, 3–9, 4–4, 4–38
Character widths
global configuration commands, 4–4
line commands, 4–38
setting for international character sets, 4–38
user commands, 3–9
CLEAR INTERFACE command, 7–9, 7–15
CLEAR LINE command, 3–4
Clear request
retransmission timer, 9–28
CLEAR X25-VC command, 9–39
CLNS
configuring for SMDS, 9–68
frame relay congestion, 9–52
Phase IV, frame relay congestion, 9–52
CMNS
configuration examples, 9–44
configuration steps, routing, 9–43
debugging, 9–51
Digital support defined, 9–42
enabling, 9–43
interface subcommand summary, 9–73
monitoring LLC2 parameters, 9–49
monitoring traffic activity, 9–48
specifying address mappings, 9–43
virtual circuit, displaying active, 9–50

Index–2

CMNS ENABLE command, 9–43
Command collection mode
configuring, 4–37
Command interpreter, EXEC, 2–7
Commands
abbreviating, 2–7
correcting entries, 2–7
levels, 2–7
listing, 2–7
negating, 2–9
upper- and lowercase, 2–7
Command summary
CMNS subcommands, 9–73
EXEC system management, 6–12
EXEC terminal, 3–11
frame relay subcommands, 9–74
global configuration commands, interface, 7–44
interface configuration subcommands, adjusting,
8–13
interface support EXEC command, 7–49
interface support subcommands, 7–45
LAPB subcommands, 9–75
line configuration subcommands, 4–51
SMDS subcommands, 9–76
system configuration, 4–43
X.25 global commands, 9–71
X.25 interface subcommands, 9–77
Community string
default access, 4–29
SNMP access, 4–29
Configuration
erasing system information, 6–11
global system command summary, 4–43
line subcommand summary, 4–51
writing system information, 6–11
Configuration commands
abbreviating, 2–9
correcting entries, 2–9
entering, 2–9
global, 2–9, 2–10
interface, 2–9, 2–10
line subcommands, 2–9, 2–10
negating, 2–9
router, 2–9, 2–11
Configuration file
auto load, 2–13
autoloading, 4–33
automatic execution of, 2–12
changing filename, 4–6
changing host name, 4–7
changing network name, 4–6
creating, 2–11
examples, 2–10
failing to load, 2–14
loading, 2–14, 4–7
through TFTP, 2–14
network, 2–13
setting specifications, 4–6

Configuration methods
auto load, 2–13
from console, 2–12
from nonvolatile memory, 2–12
from remote hosts, 2–13
Configuration mode
entering, 2–8
Configuration script
system startup, 2–3
CONFIGURE command, 2–9
Configuring datagram transport, 9–34
CONNECT command, 3–1
Connections
aborting, 3–4
disconnecting, 3–4
displaying active, 3–2, 3–6
displaying TCP, 3–5
establishing restrictions, 4–39
Telnet, incoming, 3–5, 4–39
Telnet, outgoing, 4–39
Console
configuring from, 2–12
displaying debug messages, 3–8
line, configuring, 4–37
logging messages to, 4–34
Controller
status, displaying, 7–4
COPY FLASH TFTP command, 4–17
Copy MOP image
to Flash memory, 4–15
Copy Process
aborting, 5–8
COPY TFTP FLASH command, 4–13
Counters
clearing, 7–3
CSC-1R, 7–4
CSC-2R, 7–4
CSC-ENVM
See ENVM card
CSC-R, 7–4
CSC-R16, 7–4
CSC-R16M, 7–4
CSU/DSU
loopback, 8–11
CUG number, 9–9, 9–81

D
Datagram transport
configuring on DDN, 9–34
Data structures
resetting, 3–4
DCE
dial-on-demand routing, 7–23
use in LAPB, 9–2

DCE clear request retransmission timer
setting, 9–28
DCE request retransmission timer
setting, 9–27
DCE reset request retransmission timer
setting, 9–28
DDN
configuring X.25, 9–18
conversion scheme, 9–38
encapsulation, 9–34
X.25 basic service, 9–34
X.25 configuration subcommands, 9–39
X.25 standard service, 9–34
DDR
access list configuration examples, 7–35
assigning access lists, 7–32
carrier wait-time, 7–26
configuring, 7–23
debugging, 7–40
DECbrouter 90implementation, 7–23
dialer idle time, 7–25
dialer rotary groups, 7–31
monitoring routing, 7–38
multiple destinations, 7–28
setting interface idle time, 7–25
specifying dialer enable time, 7–26
specifying dialer type, 7–24
specifying multiple destinations, 7–29
specifying single DDR telephone number, 7–27
specifying strings passed to DCE, 7–27
specifying V.25bis dialing, 7–25
using access lists with, 7–33
V.25bis conformance, 7–23
DDR implementation, 7–23
DDR interface
assigning access lists, 7–32, 7–33
DEBUG ? command, 6–8
DEBUG ALL command, 6–8
DEBUG ARP command, 9–71
DEBUG BROADCAST command, 7–19
DEBUG command, 6–8
DEBUG FRAME-RELAY-EVENTS command,
9–61
DEBUG FRAME-RELAY-LMI command, 9–61
DEBUG FRAME-RELAY-PACKET command,
9–61
Debugging
diagnostics, 6–8
dial-on-demand routing (DDR), 7–40
Ethernet interface, 7–19
real-time support, 6–8
serial interface, 7–13
timestamping, 6–8
use of trace command, 6–11
DEBUG LAPB command, 9–4
Debug messages
displaying on terminal or console, 3–8

Index–3

DEBUG MOP command, 3–10
DEBUG PACKET command, 7–19
DEBUG SERIAL-INTERFACE command, 7–13,
7–40, 7–42, 9–71
DEBUG SERIAL-PACKET command, 7–13, 7–40
DEBUG X25 command, 9–41, 9–51
DEBUG X-25 EVENTS command, 9–41
DEBUG X25-EVENTS command, 9–51
DEBUG X25-VC command, 9–41, 9–51
DEC MOP
server, 3–10
DECnet
routing over frame relay, 9–58
DEFAULT command, 8–6
DEFAULT-VALUE EXEC-CHARACTER-BITS
command, 4–4, 4–45
DEFINE MODULE CONFIGURATOR command,
3–10
Delay
backup line, 7–21
setting on interface, 8–10
DELAY command, 8–10
Delimiting character
in banner messages, 4–2
DESCRIPTION command, 7–2
Descriptive name
adding to interface, 7–2
Diagnostics
enabling output, 6–8
Dial backup
configuration examples, 7–22
line, configuring, 7–20
service, configuring, 7–19
DIALER ENABLE-TIMEOUT command, 7–26
DIALER FAST-IDLE command, 7–25
DIALER-GROUP command, 7–32
DIALER IDLE-TIMEOUT command, 7–25
DIALER IN-BAND command, 7–24
DIALER-LIST command, 7–33
DIALER MAP command, 7–29, 7–47
DIALER MAP commands, 7–29
DIALER-ROTARY command, 7–47
DIALER ROTARY-GROUP command, 7–31
Dialer rotary groups, 7–31
DIALER STRING command, 7–27
Dialer type
specifying, 7–24
DIALER WAIT-FOR-CARRIER-TIME command,
7–26
Dial-on-demand routing
access-list examples, 7–35
configuring, 7–23
debugging, 7–40
DISCONNECT command, 3–4
Displaying
incoming message banner, 4–3
message-of-day, 4–2

Index–4

DLCI
defining for multicast, 9–57
mapping, 9–54
setting local, 9–56
DNS
using, 2–14
DTE
use in LAPB, 9–2
DTR
signal pulsing, 8–1
Dynamic buffer sizing, 4–5

E
EGP
support in router, 1–2
ENABLE command, 2–7, 2–8, 4–19
ENABLE LAST-RESORT command, 4–25
ENABLE PASSWORD command, 4–19
ENABLE-PASSWORD command, 2–7
ENABLE USE-TACACS command, 4–24
Encapsulation
DDN X.25, 9–34
Ethernet interface, 7–14
serial interface, 7–8
ENCAPSULATION BFEX25 command, 9–35
ENCAPSULATION command, 7–8, 7–14, 9–2,
9–34
ENCAPSULATION FRAME-RELAY command,
9–53
ENCAPSULATION HDLC command, 7–9
ENCAPSULATION PPP command, 7–40
ENCAPSULATION SMDS command, 9–63
ENCAPSULATION X25 command, 9–7
ENCAPSULATION X25-DCE command, 9–8
Encrypting passwords, 4–21
Error logging conditions
displaying syslog, 6–6
Error messages
logging, 4–33
redirecting, 4–33
setting levels, 4–34
Escape character
Break key, 4–41
setting system, 4–41
ESCAPE-CHARACTER command, 3–2, 4–41
Escape sequence
Telnet connection, 3–2
Ethernet cards
loopback on, 8–11
Ethernet interface
cards, 7–14
clearing, 7–15
configuring, 7–14
debugging, 7–19
encapsulation methods, 7–14
maintaining, 7–15
monitoring, 7–15

Ethernet interface (cont’d)
show interfaces field descriptions, 7–16
specifying, 7–14
support, 7–14
EXEC
system management, command summary, 6–12
EXEC-BANNER command, 4–40
EXEC-CHARACTER-BITS command, 4–38, 4–52
EXEC commands
displaying, 2–7
entering, 2–8
help, 2–7
multiple screen output, 2–7
syntax, 2–7
terminal command summary, 3–11
using command interpreter, 2–7
EXEC-TIMEOUT command, 4–42
EXIT command, 3–3
Extended TACACS mode
enabling, 4–25

F
FECN, 9–52
File loading
configuration, 2–13, 4–7
Filenames
changing default, 4–6
changing host configuration, 4–7
changing network configuration, 4–6
Finger protocol, 4–33
Flash Memory
automatically booting from, 4–16
booting system software, 4–8
configuring, 4–8
copying image, 4–17
copying TFTP image, 4–13
displaying statistics, 4–9
erasing, 5–6
manually booting from, 4–17
saving configuration first, 4–8, 4–13
security precautions, 4–8
statistics, 4–9
storing system software, 4–8
using, 2–15
Flash Memory card
also known as CSC-MC+, 4–8
verifying installation, 4–8
Flash Memory statistics
verifying installation, 4–9
Flash ROM statistics
displaying, 4–9
verifying installation, 4–9
Flow control modulus
setting, 9–29
Frame
setting parameters, 9–3

Frame relay
configuring, 9–51
configuring for ISO CLNS, 9–55
congestion information, 9–52
debugging, 9–61
displaying global statistics, 9–60
displaying map entries, 9–60
enabling ANSI LMI, 9–53
encapsulation, specifying, 9–53
examples, 9–57
FECN, 9–52
hardware configuration, 9–52
IP split horizon, default, 9–52
keepalive timer, 9–54
local DLCI, 9–56
map entries, 9–60
monitoring, 9–58
multicast DLCI, 9–57
short status messages, 9–56
static routing example, 9–57
subcommand summary, 9–74
FRAME-RELAY KEEPALIVE command, 9–54
FRAME-RELAY LOCAL-DLCI command, 9–56
FRAME-RELAY MAP BRIDGE command, 9–55
FRAME-RELAY MAP CLNS command, 9–55
FRAME-RELAY MAP command, 9–54, 9–55
FRAME-RELAY MULTICAST-DLCI command,
9–57
FRAME-RELAY SHORT-STATUS command, 9–56
FRAM-RELAY LMI-TYPE ANSI command, 9–53

G
Global configuration commands, 2–10
entering, 2–9
Global Configuration commands
username name, 4–27
Global configuration command summary
packet-switched software, 9–71
Global system configuration
command summary, 4–43
Global system parameters
configuring, 4–1

H
HDLC
serial encapsulation method, 7–9
HELP command, 2–7
Hold queue, 8–8
HOLD-QUEUE command, 8–8
Host
writing configuration to, 6–11
Host configuration file, 4–7
changing name, 4–7
Host name
assigning, 4–1
setting, 4–1, 4–22

Index–5

HOSTNAME command, 2–7, 4–1

I
Idle time
setting, 7–25
IEEE 802.2
LLC encapsulation, 7–14
IEEE 802.3
encapsulation, 7–14
Ignore VC timer
configuring, 9–27
IGRP
support in router, 1–2
Interface
adding descriptive name, 7–2
assigning priority group, 8–7
assigning queuing priority, 8–6
clearing counters, 7–3
configuration subcommand summary, 8–13
displaying controller status, 7–4
displaying information about, 7–3
displaying statistics, 7–6
displaying system configuration, 7–3
global command summary, interface support,
7–44
hold queues, 8–8
loopback on Ethernet, 8–11
monitoring, frame relay, 9–58
null, 7–44
parameters and statistics, displaying, 9–39
priority queuing, 8–2
restarting, 7–2
setting bandwidth on, 8–9
setting delay value, 8–10
settings, overriding, 9–32
shutting down, 7–2
specifying, 7–1
subcommand summary, interface support, 7–45
unit numbers, 7–1
Interface, global command summary
interface characteristics, 8–12
Interface, subcommand summary
frame relay, 9–74
interface characteristics, 8–13
LAPB, 9–75
packet-switched software, 9–73
SMDS, 9–76
X.25, 9–77
INTERFACE command, 7–1, 8–6
Interface configuration
global command summary, 8–12
INTERFACE DIALER command, 7–31
INTERFACE ETHERNET command, 7–14
Interfaces
adjusting characteristics, 8–2

Index–6

INTERFACE SERIAL command, 7–7
Internal buffer
message logging, 4–34
International characters
setting default widths, 4–4
setting widths at EXEC level, 3–9
IP
configuring for SMDS, 9–67
IP split horizon
frame relay default, 9–52
SMDS default, 9–62
X.25 default, 9–6
IP UDP command, 8–4
ISDN
dialer map, 7–29, 7–30
ISO-IGRP
support in router, 1–2

K
Keepalive timer
frame relay, 9–54
Keywords
retransmission timer, 9–27
SVC range limit, 9–24

L
LAPB
configuring, 9–1
debugging, 9–4
displaying statistics, 9–4
encapsulation, 9–2
encapsulation sample, 9–2
encapsulation with a single protocol, 9–2
encapsulation with multiple protocols, 9–2
interface subcommand summary, 9–75
monitoring, 9–4
setting Level 2 parameters, 9–2
setting retransmission timer, 9–3
troubleshooting, 9–4
using leased serial line, 9–1
LAPB K command, 9–4
LAPB N1 command, 9–3
LAPB N2 command, 9–4
LAPB PROTOCOL command, 9–2
LAPB T1 command, 9–3
Last resort login feature
enabling privileged mode, 4–25
setting, 4–24, 4–25
LENGTH command, 4–42
Level 3
X.25, monitoring, 9–39
X.25, retransmission timer, 9–27
Line
clearing, 3–4
configuration, starting, 4–37
configuration, subcommand summary, 4–51

Line (cont’d)
displaying active, 3–6
numbers, decimal, 4–33
numbers, octal, 4–33
numbers, specifying terminal, 4–37
password, specifying, 4–20
LINE command, 2–11, 4–37
Link level
restart, 9–32
Listing connections, 3–2
LOCATION command, 4–41
Logging
displaying syslog, 6–6
LOGGING BUFFERED command, 4–34
LOGGING command, 4–36
LOGGING CONSOLE command, 4–34
LOGGING MONITOR command, 4–35
LOGGING ON command, 4–34
LOGGING TRAP command, 4–36
Login
limiting attempts, 4–23
LOGIN command, 4–20
LOGIN TACACS command, 4–20
Loopback
test, description of, 8–11
Lost password
recovering from, 4–21

M
Map
displaying address, 9–14
dynamic Internet-to-X.121 address, 9–37
frame relay, 9–54, 9–60
network-protocol-to-X.121-address, 9–8, 9–14
protocol-to-virtual-circuit, 9–13
SMDS multicast address, 9–65
SMDS static, 9–65
Mapping
between address and DLCI, 9–54
to multicast address, SMDS, 9–65
M-bit
use in X.25, 9–29
Memory
displaying system statistics, 6–3
testing, 6–12
Memory utilization
displaying, 6–5
Message logging
enabling, 4–34
keywords and levels, 4–35
to another monitor, 4–35
to a UNIX syslog server, 4–36
to internal buffer, 4–34
to the console, 4–34
Message-of-the-day banner
displaying, 4–2

Message queue length
SNMP server, 4–29
Messages
displaying on terminal or console, 3–8
short status, frame relay, 9–56
MIB
FDDI support, 4–28
RFCs, 4–28
source-route bridging support, 4–28
support, 4–28
Monitor
logging messages to, 4–34
MOP
configuring, 5–2
copying image to Flash Memory, 5–4
debugging, 5–9
enabling for an interface, 5–2
system ID messages, 5–2
using, 5–1
MOP, DEC server, 3–10
More bit
use in X.25, 9–29
More data bit, 9–41
More prompt
use in multiple screen output, 2–7
MTU command, 8–10
MTU size
adjusting media MTU, 8–10
default media MTU table, 8–10
Multibus memory
testing, 6–12
Multicast
SMDS address mapping, 9–65

N
NAME-CONNECTION command, 3–3
Netbooting
specifying buffer size, 4–7
Network configuration file
changing name, 4–6
copying to a remote host, 2–13
Network protocol
X.25, 9–2
Network-protocol-to-X.121
display address mapping, 9–38
Network services
tailoring use of, 4–33
NFS
port number, 8–4
Nonvolatile memory
checksum protection, 2–12
clearing contents of, 2–12
erasing configuration from, 6–11
executing commands automatically at startup,
2–12
password checking, 4–20
writing configuration file to, 2–12, 6–11

Index–7

NO SNMP-SERVER command, 4–28
Notification
pending output, 4–43
setting, 4–43
NOTIFY command, 4–43
Novell IPX
configuring
for SMDS, 9–67
routing over frame relay, 9–58
Null interface
configuring, 7–44

O
Operating system
reloading, 2–15
Optical bypass switch
bypass mode, 7–2
Optional password verification, 4–26
Order of banner displays, 4–3
OSPF
support in router, 1–2

P
Packet filtering
establishing size, 4–30
Packet hold queue
defining X.25, 9–31
Packet-level restarts
forcing X.25, 9–32
Packets
network carrier, X.25, 9–32
Packet size
setting maximum, 8–10
X.25, specifying output, 9–29
Padding
character setting, 4–43
PADDING command, 4–43
Password
assigning, 4–20
for privileged level access, 2–7
line, establishing, 4–38
optional, 4–26
privileged-level, 4–19
recovering from lost, 4–21
specifying, 4–20
PASSWORD command, 4–20, 4–38
Password encryption, 4–21
Pending output
terminal notification of, 4–43
Permissions
access list, 4–28
PING
aborting session, 6–10
definition of, 6–10
testing connectivity, 6–10
X.25 support over multiple serial lines, 9–10

Index–8

Port
prioritizing, 8–4
PPP
configuring, 7–40
PPP AUTHENTICATION CHAP command, 7–41,
7–49
PRIORITY-GROUP command, 8–7
Priority list
definition, 8–3
PRIORITY-LIST command, 8–3, 8–6
Priority queuing
assigning default, 8–6
assigning to an interface, 8–6, 8–7
assigning to a protocol, 8–3
by interface type, 8–3
by serial link address, 8–8
definition, 8–2
group, 8–7
interface, 8–2
maximum packets, 8–6
monitoring, 8–7
types of, 8–2
Privileged-level commands
definition, 2–7
Privileged mode last resort login
enabling, 4–25
Protocols
counted per packet, 7–6
displaying configured, 6–7
Finger, 4–33
specific configuring, 9–66
supported by X.25, 9–6
Protocol-to-virtual-circuit
mapping, 9–13
Protocol-to-X.121
address mapping, 9–38
PULSE-TIME command, 8–1
PVC
serial interfaces, 9–21
TCP connection, 9–22
X.25 Network, 9–13
PVCs
configuring switched, 9–21
highest incoming circuit number, 9–25
highest outgoing circuit number, 9–26
highest two-way circuit number, 9–25
lowest incoming circuit number, 9–25
lowest outgoing circuit number, 9–25
lowest two-way circuit number, 9–25
setting, 9–11

Q
Question mark (?) command, 2–7
Queue
controlling hold, 8–8

Queue length
SNMP server, 4–29
QUEUE-LIMIT command, 8–6
QUIT command, 3–3

R
Range limit keywords for SVCs, 9–24
RELOAD command, 2–15
Remote Router Management, 5–8
Reset request
retransmission timer, 9–28
Restart
packet-level, 9–32
retransmission timer request, 9–27
RESUME command, 3–3
Retransmission timer
call request, 9–28
clear request, 9–28
keywords and defaults, 9–27
reset request, 9–28
restart request, 9–27
setting for LAPB, 9–3
X.25 Level 3, 9–27
Retries
controlling, 4–23
Reverse charge calls
accepting X.25, 9–31
configuring X.25, 9–10
RIP
support in router, 1–2
Router
assigning host name, 4–1
capabilities, 1–1
changing host name, 4–1
communicating through X.25 network, 9–8
multiple protocol support, 1–1
priority queuing, 8–2
Routing protocols
support for native, 1–2
RPC
port number, 8–4

S
SCHEDULER-INTERVAL command, 8–2
Screen
setting length, 4–42
SDSU
SMDS, 9–62
Security
establishing, 4–19
password encryption, 4–21
Security precautions
with Flash Memory card, 4–8
Serial interface
adjusting characteristics, 8–1
clearing, 7–9

Serial interface (cont’d)
configuring, 7–7
debugging, 7–13
DTR signal pulsing, 8–1
encapsulation methods, 7–8
leased serial line, using LAPB, 9–1
loopback test on, 8–11
maintaining, 7–9
monitoring, 7–9
show interfaces field descriptions, 7–11
specifying, 7–7
support, 7–7
transmit delay, 8–1
SERVICE command, 4–33
SERVICE CONFIG command, 2–14
SERVICE CONFIG MEMORY command, 2–13
SERVICE PASSWORD-ENCRYPTION command,
4–21
Services
network, tailoring use of, 4–33
SERVICE TIMESTAMPS command, 6–8, 6–13
Sessions
displaying active, 3–5, 3–6
exiting, 3–3
SETUP command, 2–1
SETUP command facility
capabilities, 2–1
configuring protocols, 2–1
prompts displayed by, 2–3
using, 2–2
Short status messages
frame relay, requesting, 9–56
SHOW ? command, 6–1
SHOW BUFFERS command, 4–5, 6–2
SHOW CMNS command, 9–48
SHOW command, 6–1
SHOW CONFIGURATION command, 2–12, 6–6
SHOW CONTROLLERS command, 7–4
SHOW CONTROLLER SERIAL command, 7–7
SHOW DEBUGGING command, 6–8
Show dialer, 7–38
SHOW DIALER INTERFACE command, 7–38
SHOW FLASH ALL command, 4–9
SHOW FLASH command, 4–9
SHOW FRAME-RELAY MAP command, 9–60
SHOW FRAME-RELAY TRAFFIC command,
9–60
SHOW INTERFACE command, 9–59
SHOW INTERFACES ACCOUNTING command,
7–6
SHOW INTERFACES command, 9–4, 9–39
SHOW LOGGING command, 4–34, 4–36, 6–6
SHOW MEMORY command, 6–3
SHOW PROCESSES command, 6–4
SHOW PROCESSES MEMORY command, 6–5
SHOW PROTOCOLS command, 6–7

Index–9

SHOW SESSIONS command, 3–6
SHOW SMDS ADDRESSES command, 9–70
SHOW SMDS MAP command, 9–70
SHOW SMDS TRAFFIC command, 9–70
SHOW STACKS command, 6–6
SHOW TCP command, 3–5
SHOW TERMINAL command, 3–6, 3–9
SHOW USERS command, 3–6
SHOW VERSION command, 7–3
SHOW X25 MAP command, 9–8, 9–38
SHOW X25 REMOTE-RED command, 9–37
SHOW X25 ROUTE command, 9–19
SHOW X25 VC command, 9–39
Shutdown
interface, 7–2
SNMP system, 4–32
SHUTDOWN command, 7–2
Signals
pulsing DTR, 8–1
Single DDR telephone number
specifying, 7–27
SMDS
ARP, enabling, 9–64
arp command, 9–67
assigning addresses, 9–63
AT&T version, 9–66
configuration examples, 9–68
configuring, 9–61, 9–62, 9–68
counters, displaying, 9–70
debugging, 9–71
displaying addresses, 9–70
displaying counters, 9–70
DS1, 9–61
enabling, 9–63
encapsulation, 9–63
hardware requirements, 9–62
interface subcommand summary, 9–76
IP fast switching, 9–68
IP split horizon, default, 9–62
mapped addresses, displaying, 9–70
monitoring, 9–70
multiprotocol configuration, 9–68
protocol-specific configuration, 9–66
protocols supported, 9–67
remote peer configuration, 9–69
SDSU, 9–62
special SMDS, 9–62
specifying address, 9–64
static map, 9–65
static map for individual, SMDS, 9–65
subcommand summary, 9–76
using addresses, 9–63
SMDS ADDRESS command, 9–64
SMDS D15 MODE command, 9–66
SMDS ENABLE-ARP command, 9–64
SMDS MULTICAST command, 9–65

Index–10

SMDS STATIC-MAP command, 9–65
SMTP
port number, 8–4
SNMP
configuring, 4–28
port number, 8–4
system shutdown, 4–32
SNMP server
community string, 4–29
configuring, 4–29
defining access list, 4–28
message queue length, 4–29
packet filtering, 4–30
setting community access, 4–29
TRAP messages, 4–30
SNMP-SERVER ACCESS-LIST command, 4–28
SNMP-SERVER COMMUNITY command, 4–29
SNMP-SERVER HOST command, 4–30
SNMP-SERVER PACKETSIZE command, 4–30
SNMP-SERVER QUEUE-LENGTh command,
4–29
SNMP-SERVER SYSTEM-SHUTDOWN command,
4–32
SNMP-SERVER TRAP-AUTHENTICATION
command, 4–31
SNMP-SERVER TRAP-TIMEOUT command,
4–31
Software
displaying version level, 2–3
SPECIAL-CHARACTER-BITS command, 4–38,
4–53
Stack utilization
displaying, 6–6
Statistics, 4–9
buffer pool, 6–2
displaying for network interfaces, 7–6
Storing system software
using the Flash Memory card, 4–8
SVC
clearing, 9–26, 9–39
displaying active, 9–40
displaying CMNS information, 9–50
range limits, 9–24
X.25, 9–26
Switched PVCs
configuring, 9–21
Switching
configuring X.25, 9–18
PVC on X.25, 9–21
X.25 local, 9–6
X.25 remote, 9–6
Switching operations
changing priorities, 8–2
system process scheduler, 8–2
Symbols
> (angle bracket)
as system prompt, 2–7
? (question mark) command

Symbols
? (question mark) command (cont’d)
use of, 2–7
Syslog daemon, 4–36
Syslog messages
levels of, 4–36
Syslog server
limiting messages to, 4–36
Syslog server, UNIX
logging messages to, 4–36
SYSTAT command, 4–41
System
monitoring processes, 6–1
testing, 6–12
writing configuration information, 6–11
System buffers
changing size of, 4–6
setting, 4–5
System configuration
copying to memory, 6–11
displaying, 6–6
displaying interface information, 7–3
erasing information, 6–11
writing information, 6–11
writing to a host, 6–11
writing to nonvolatile memory, 6–11
System configuration dialog
first-time system startup, 2–3
System escape character
setting, 4–41
System file names
changing, 4–6
System host name
assigning, 2–7
System images
obtaining through TFTP, 2–14
System management
command summary, 6–12
System memory
displaying statistics, 6–3
testing, 6–12
System processes
changing priorities, 8–2
displaying active, 6–4
monitoring, 6–1
System prompt
EXEC, 2–7
privileged level, 2–7
user level, 2–7
using "More" with multiple screens, 2–7
System setup
using the SETUP command facility, 2–1
System software
booting with Flash Memory, 2–15
storing with Flash Memory, 2–15
System startup
configuration script, 2–3
first-time, 2–3

T
TACACS
accounting
configuring, 4–25
controlling retries, 4–23
definition, 4–19
establishing privileged-level, 4–24
extended mode, 4–25
last resort login, 4–24
limiting login attempts, 4–23
login authentication, 4–26
login notification, 4–26
optional password verification, 4–26
privileged mode, 4–24
server not responding, 4–24
setting server host name, 4–22
timeout interval, 4–23
TACACS-SERVER ATTEMPTS command, 4–23
TACACS-SERVER AUTHENTICATE command,
4–26
TACACS-SERVER EXTENDED command, 4–25
TACACS-SERVER HOST command, 4–22
TACACS-SERVER LAST-RESORT command,
4–24
TACACS-SERVER NOTIFY command, 4–26
TACACS-SERVER OPTIONAL-PASSWORDS
command, 4–26
TACACS-SERVER RETRANSMIT command,
4–23
TACACS-SERVER TIMEOUT command, 4–23
TCP
common services, 8–4
TCP connections
displaying status, 3–5
TCP header compression, X.25, 9–33
TCP/IP
running X.25 over, 9–18
Telnet
port number, 8–4
table of special commands, 3–4
TELNET command, 3–1
Telnet connections
creating, 3–1
disconnecting, 3–4
ending a session, 3–3
escape sequence, 3–2
incoming, 3–5, 4–39
leaving, 3–2
listing, 3–2
multiple, 3–2
naming, 3–3
options, 3–5
outgoing, 4–39
resuming, 3–3
switching between, 3–2

Index–11

Terminal
changing the screen length, 3–7
changing the screen width, 3–7
changing the terminal escape character, 3–7
character padding, 3–8
configuring from, 2–12
displaying debug messages, 3–8
establishing input notification, 3–8
location setting, 4–41
parameters, changing, 3–6
parameters, display of active, 3–6
parameters, listing commands, 3–6
setting screen length, 4–42
writing configuration to, 6–12
Terminal ? command, 3–6
Terminal access control
establishing, 4–22
TERMINAL command, 2–12
TERMINAL ESCAPE-CHARACTER command,
3–7
TERMINAL EXEC-CHARACTER-BITS command,
3–9, 3–12
TERMINAL LENGTH command, 3–7
Terminal location
setting, 4–41
TERMINAL MONITOR command, 3–8, 4–35
TERMINAL NOTIFY command, 3–8
TERMINAL PADDING command, 3–8
Terminal special-character-bits, 3–9, 3–13
TERMINAL WIDTH command, 3–7
Terminating processes, 3–4
Testing the system, 6–12
TEST INTERFACES command, 6–12
TFTP
autoloading configuration files, 4–33
copying image to Flash Memory, 4–13
port number, 8–4
server, configuring, 4–32
server, loading files from, 4–7
using to load configuration files, 2–14
using to load system images, 2–14
TFTP server
configuring, 4–32
copying Flash Memory image, 4–17
TFTP-SERVER SYSTEM command, 4–32
Timeout interval
setting EXEC, 4–42
system default, 4–42
system setting, 4–42
TACACS, 4–25
Timers
ignore VC, 9–27
keepalive, 9–54
TRACE
extended test, 6–11
terminating, 6–11
use in debugging, 6–11

Index–12

TRACE command, 6–11
Traffic load threshold
default, 7–20
defining, 7–20
Translating called addresses, X.25, 9–20
Transmit delay
serial interface, 8–1
TRANSMITTER-DELAY command, 8–1
TRAP host
message length queue, 4–29
TRAP message
authentication, 4–31
resending, 4–31
specifying recipient, 4–30
timeout, 4–31
Troubleshooting
network operations, 6–8
Tunneling
enabling for X.25, 9–19
Type of Service (TOS) field, 9–39

U
UDP
common services, 8–4
port prioritizing, 8–4
Unit numbers, interface, 7–1
UNIX syslog server
logging messages to, 4–36
User-level commands
definition, 2–7
User name authentication, 4–27
USERNAME command, 4–27
Username name password secret command, 7–42

V
V.25bis dialing
DECbrouter 90 support, 7–23
support, 7–24
Vacant banner
turning on/off, 4–40
VACANT-MESSAGE command, 4–40
VC ignore timer
configuring, 9–27
Virtual circuit
clearing, 9–26
clearing X.25, 9–39
displaying active, 9–40, 9–50
maintaining, 9–26
Virtual circuit channel sequence
range limit keywords, 9–24
Virtual circuit ranges
configuring, 9–24
Virtual terminal line
configuring, 4–37
configuring group of, 4–37

W
WHERE command, 3–2
Window modulus, 9–29
Window sizes, 9–30
WRITE ERASE command, 2–11, 2–13, 6–11
WRITE MEMORY command, 2–11, 2–13, 6–11
WRITE NETWORK command, 2–12, 2–13, 4–7,
6–11
WRITE SERVICE command, 2–13
WRITE TERMINAL command, 2–11, 4–7, 6–12

X
X.121 address, 9–19
DDN conversion table, 9–38
display address mapping, 9–14, 9–38
mapping, 9–8
setting, 9–23
updating, 9–29
X.25
address mapping
displaying, 9–14
issues, 9–8
setting, 9–8
bridging on, 9–34
clearing virtual circuits, 9–39
command summary, 9–71
communicating via routers, 9–8
configuration example, 9–16
configuring, 9–5, 9–10
connecting networks via TCP/IP network, 9–6
constructing routing table, 9–19
datagram transport, 9–6
DDN configuration subcommands, 9–39
debugging, 9–41
displaying interface parameters, 9–39
displaying interface statistics, 9–39
enabling switching, 9–19
encapsulation methods, 9–7
forwarding calls, 9–19
frame parameters, 9–3
global command summary, 9–71
header compression, TCP, 9–33
interface subcommand summary, 9–75, 9–77
IP split horizon, default, 9–6
maintaining, 9–39
multiple network protocols, 9–2
remote switching, 9–6
routing through LAN, 9–18
running on TCP/IP, 9–18
setting interface address, 9–23
setting packet sizes, 9–29
single network protocol, 9–2
subcommand summary, 9–77
support, 9–6
supported protocols, 9–6

X.25 (cont’d)
switch, 9–6
switching subsystem, 9–19
TCP header compression, 9–33
translating addresses, 9–20
X.25 configuration
switching, 9–22
X.25 Level 2
configuring parameters, 9–2
restart, 9–32
X.25 Level 3
monitoring, 9–39
retransmission timer, 9–27
setting parameters, 9–23
X.25 parameters
displaying interface, 9–39
Level 2, LAPB, 9–2
Level 3, 9–23
setting frame, 9–3
setting per-call, 9–23, 9–32
X25 ACCEPT-REVERSE command, 9–31
X25 ADDRESS command, 9–23
X25 BFE-DECISION command, 9–36, 9–71
x25 BFE-EMERGENCY command, 9–35
X25 BFE-EMERGENCY command, 9–72
X25 DEFAULT command, 9–14
X25 FACILITY command, 9–32
X25 HIC command, 9–25
X25 HOC command, 9–26
X25 HOLD-QUEUE command, 9–31
X25 HOLD-VC-TIMER command, 9–27
X25 HTC command, 9–25
X25 IDLE command, 9–26
X25 IP-PRECEDENCE command, 9–39
X25 IPS command, 9–29
X25 LIC command, 9–25
X25 LINKRESTART command, 9–32
X25 LOC command, 9–25
X25 LTC command, 9–25
X25 MAP BRIDGE command, 9–34, 9–81
X25 MAP CMNS command, 9–43
X25 MAP command, 9–8
X25 MAP COMPRESSEDTCP command, 9–33
X25 MODULO command, 9–29
X25 NVC command, 9–26
X25 OPS command, 9–29
X25 PVC command, 9–11, 9–21
X25 REMOTE-RED command, 9–35, 9–72
X25 ROUTE command, 9–19
X25 ROUTING command, 9–19
X25 RPOA command, 9–32
X25 SUPPRESS-CALLED-ADDRESS command,
9–31
X25 SUPPRESS-CALLING-ADDRESS command,
9–31
X25 T10 command, 9–27

Index–13

X25 T11 command, 9–28
X25 T12 command, 9–28
X25 T13 command, 9–28
X25 T20 command, 9–27
X25 T21 command, 9–28
X25 T22 command, 9–28
X25 T23 command, 9–28
X25 TH command, 9–30
X25 USE-SOURCE-ADDRESS command, 9–29
X25 WIN command, 9–30
X25 WOUT command, 9–30
XNS
configuring for SMDS, 9–67
XNS, configuring for SMDS, 9–67

Index–14