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EK-DECMR-OM-002

September 1991

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Document:	DECrepeater 90C Owners Manual
Order Number:	EK-DECMR-OM
Revision:	002
Pages:	59
Original Filename:

OCR Text

DECrepeater 90C Owner’s Manual
Order Number EK–DECMR–OM.002

Digital Equipment Corporation

Second Edition, September 1991
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.
Copyright © Digital Equipment Corporation 1991
All Rights Reserved.
Printed in U.S.A.
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, DECbridge,
DECconnect, DEChub, DECnet, DECrepeater, DECserver, MicroVAX, UNIBUS, VAX, VAX
6000, VAX 9000, VAX–11/780, VAXstation, VMS, and the Digital logo.
This document was prepared and published by Educational Services Development and
Publishing, Digital Equipment Corporation.

Contents
About This Manual
1

Overview

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LEDs and Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1–1
1–3
1–4

Configuration

Configuration Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Port Termination and Grounding . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Port Partitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vii

2–1
2–1
2–1
2–2

Installation

Standalone Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Select a location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Place the repeater on a table. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mount the repeater on a wall. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connect the cables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Install and verify devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Backplane Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remove the back cover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mount the repeater in the backplane. . . . . . . . . . . . . . . . . . . . . .
Install and verify devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

iii

iv Contents

Management

Managing the DECrepeater 90C . . . . . . . . . . . . . . . . . . . . . . . . . . .
Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Components Needed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessing the MOP from VMS . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessing the MOP from ULTRIX . . . . . . . . . . . . . . . . . . . . . . . .
Console Carrier User Interface . . . . . . . . . . . . . . . . . . . . . . . . . .
Console Carrier Command Language . . . . . . . . . . . . . . . . . . . . . . . .
Command Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Command Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Typical Management Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote Network Management With the DECbridge 90 . . . . . . . .
Management Disconnect . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Management Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If Problems Are Reported . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standalone Configuration Management . . . . . . . . . . . . . . . . . . . .

Troubleshooting

DECrepeater 90C Standalone Troubleshooting . . . . . . . . . . . . . . . .
DECrepeater 90C Backplane Configuration Troubleshooting . . . . . .

4–1
4–1
4–2
4–2
4–3
4–4
4–5
4–6
4–6
4–11
4–11
4–11
4–13
4–14
4–16
4–18

5–2
5–6

DECrepeater 90C Specifications

Physical Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping Environment Specifications . . . . . . . . . . . . . . . . . . . . . .
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DECrepeater 90C Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A–1
A–2
A–2
A–2
A–3
A–3
A–3
A–3

Contents v

Related Documentation

Management Details

Designating a Hub Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Annotating the Bridge Address Table . . . . . . . . . . . . . . . . . . . . . . .
Using the WGB Address Table for Work Group Management . . .

C–1
C–2
C–3

Index
Figures
1–1
4–1
4–2
4–3

Sample DECrepeater 90C Connection . . . . . . . . . . . . . . . . . . 1–2
Sample Configuration and Topology Map . . . . . . . . . . . . . . . . 4–12
Typical Network Topology Map . . . . . . . . . . . . . . . . . . . . . . . 4–13
Typical Standalone Topology Map . . . . . . . . . . . . . . . . . . . . . 4–18

Tables
1–1
2–1
4–1
4–2
4–3
5–1
5–2

DECrepeater 90C LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–4
DECrepeater 90C Partitioning . . . . . . . . . . . . . . . . . . . . . . . . 2–2
Summary of DECrepeater 90 Commands . . . . . . . . . . . . . . . . 4–5
DECbridge 90 Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–16
DECrepeater 90C Status LEDs . . . . . . . . . . . . . . . . . . . . . . . 4–19
Troubleshooting a DECrepeater 90C Standalone Unit . . . . . . 5–2
Troubleshooting a DECrepeater 90C in a DEChub 90
Backplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5–6

About This Manual
This manual describes how to install, operate, and maintain the Digital
ThinWire multiport repeater - the DECrepeater 90C. The DECrepeater
90C is a 7-port repeater designed to work either as a standalone unit or
as a managed repeater in the DEChub 90 backplane.

Organization
This manual contains five chapters, and three appendixes.
•

Chapter 1 provides an overview of the DECrepeater 90C and
introduces you to the product’s features.

•

Chapter 2 describes the configuration rules and operating conditions
for the ThinWire multiport repeater in a ThinWire Ethernet system or
standard Ethernet network.

•

Chapter 3 provides instructions for installing the ThinWire multiport
repeater.

•

Chapter 4 provides information on managing the ThinWire multiport
repeater on a network or in a standalone configuration.

•

Chapter 5 provides basic troubleshooting information.

•

Appendix A provides product specifications and the parts list.

•

Appendix B lists related documents that can help you become more
familiar with your new system.

•

Appendix C provides more detailed information on management
issues.

vii

viii About This Manual

Conventions
This manual uses the following conventions:
Convention

Meaning

NOTE

Provides general information on the current
topic.

A number in a black circle in text refers to
the corresponding number in an accompanying
illustration.

[]

In command descriptions, brackets indicate
optional elements.

variables

In command descriptions, italic type indicates
a variable that you supply.

SHOW ADDRESS

In text, commands are shown in all upper case
letters to differentiate them from regular text.
For the VMS operating system, you can enter
commands in either upper case or lower case
letters. For the ULTRIX operating system,
commands must be entered as indicated in the
examples.

DECbridge>

Text that the system displays on the screen is
shown in monospaced type.

SHOW REPEATER 1

Text that you enter is shown in bold
monospaced type.

1
Overview
This chapter describes the features of and summarizes the installation
procedures for the DECrepeater 90C.

Features
The DECrepeater 90C provides the following features:
•

Seven ThinWire ports

•

Standalone or managed operation (on a DECbridge 90 work group
bridge)

•

Installable on a DEChub 90 backplane

The DECrepeater 90C is a 7-port repeater designed for the IEEE
802.3 CSMA/CD networks using the ThinWire Ethernet cable. The
DECrepeater 90C is also compatible with the 802.3 standard for the
10Base2 networks.
The repeater can operate in a standalone configuration or as a managed
repeater installed in Digital’s DEChub 90 Ethernet backplane with
Digital’s DECbridge 90 work group bridge. Figure 1–1 shows a typical
configuration of the DECrepeater 90C in an Ethernet local area network
(LAN).
If you use the DECrepeater 90C as a standalone unit, it operates as a 7port unmanaged repeater and uses a separate power supply. The modular
power supply connects to a 7-pin connector on the repeater and comes in
two versions, for use with 120 Volt or 240 Volt power outlets.

1–1

1–2 Overview

Workstation

DECrepeater 90T

DECserver

DECserver 90L

DECrepeater 90C

Work Group ThinWire

Segment

DECbridge 90
Work Group Bridge

Ethernet

Computer 1

Backbone

Computer 2

Server

LJ-00955-TI0

Figure 1–1

Sample DECrepeater 90C Connection

Overview 1–3

Installation
The DECrepeater 90C is easy to install and use. It does not require any
programming or other assistance from the system management. After
unpacking the repeater:
1. Plug the connector from the power supply into your DECrepeater 90C,
then plug the power supply into a working ac power outlet.
When the repeater is plugged in, all LED indicators turn on. Only the
network activity LED turns off.
2. Connect the repeater to a properly terminated ThinWire Ethernet.
3. Connect any personal computers, workstations, or other 10Base2
devices to the ports you plan to use.
The port status LEDs for unconnected ports should turn off when
network traffic is established.
For more detailed information on configuring the DECrepeater 90C, see
Chapter 2. For more detailed information on installing and using the
DECrepeater 90C, see Chapter 3.

1–4 Overview

LEDs and Connectors
The next table describes the DECrepeater 90C LEDs and connectors,
shown in the illustration following the table.
Table 1–1 DECrepeater 90C LEDs
1

Power indicator—Monitors the status of the +5.0 Vdc voltage.
On: The +5.0 Vdc voltage is normal.
Off: The voltage is abnormal (as in a power failure.)

Network activity indicator—Monitors the network activity.
On: There is network activity.
Off: There is no network activity.

Port 0 status indicator—Monitors the status of the ThinWire
input to the repeater.
On: Port 0 is functional.
Off: Port 0 has failed or has been partitioned.
Flashing: The port has been partitioned by management.

Port 1 to 8 status indicators— Monitor the activity of each
port. The top LED represents port 1, and the bottom LED
represents port 6.
On: The port has a connection.
Off: The port does not have a connection or has been partitioned.
Flashing: The port has been partitioned by management.

Port 0 network connector (BNC)— Connects the repeater to
the work group ThinWire segment. Not used when the repeater
is installed in the DEChub 90 backplane.

Port 1 to 6 connectors (BNC) – Connect DECservers,
workstations, and personal computers to the DECrepeater 90C.

Power connector—Provides +5 volts from the DECrepeater
90C power supply. Not used when the repeater is installed in the
DEChub 90 backplane.

Backplane connector—Provides network and power
connections to the DECrepeater 90C when the repeater is
installed in the DEChub 90 backplane.

Back cover—Comes on standalone units only. Covers the
backplane connector and contains a wall-mounting assembly.

Overview 1–5

1
2
3

LJ-00544-TI0

2
Configuration
This chapter contains the configuration rules you must follow for correct
installation of the DECrepeater 90C.
This chapter also contains information on port partitioning and the
different operations that cause ports to partition. The DECrepeater 90C
does not require any special instructions for it to operate correctly.

Configuration Rules
For a complete list of configuration rules, see the Open DECconnect
Building Wiring Component and Application Catalog.

Port Termination and Grounding
Each end of a ThinWire segment must be terminated with 50 ohms. The
DECrepeater 90C terminates ports 1 through 6 internally; you must
terminate the other end of the segment with a 50-ohm terminator. Port 0
is not terminated internally. Use a T-connector when connecting port 0 to
a ThinWire segment.
Each segment can have only one ground. Ports 1 through 6 only are
grounded internally; no other connections to ground are allowed. A
ThinWire segment attached to Port 0 must be grounded externally to the
repeater.

Configuration Guidelines
Digital repeaters comply with Ethernet and IEEE 802.3 standards. These
standards are subject to revision, therefore, network planners may need
to consult the standards frequently for detailed information. This chapter
contains sufficient information, however, to use the DECrepeater 90C in a
typical network configuration.

2–1

2–2 Configuration

You can have a maximum of four repeaters and five segments in a
network path between two stations. A network path with four repeaters
must have at least two point-to-point link segments. Link segments
contain two transceivers (MAUs). When not used as a point-to-point link,
a ThinWire segment may contain 30 transceivers.
NOTE
The DECrepeater 90C port has an integral transceiver.
A ThinWire segment can be a maximum of 185 meters long.

Port Partitioning
Any messages or data packets received from any port backbone by the
repeater are transmitted to all ports. The port status LEDs on the
repeater indicate the status of each port, including partitioning activity:
On

The port is either active or not partitioned.

Off

The port is autopartitioned.

Flashing

The port is partitioned by management, independent of any
other partitioning.

Each port is automatically controlled and can be partitioned for any one
of the four following reasons:
Table 2–1 DECrepeater 90C Partitioning
LED

Faults

Nonfaults

Port 0
Off

Open cables.
Shorted cables.
Cables incorrectly terminated
or connected without a T-connector.

Nothing connected to the
port.

Port 0 to 6
Flashing

—

Partitioned by
management.

Port 1 to 6
Off

Open cables.
Shorted cables.
Cables improperly terminated by
using a T-connector.

Nothing connected to the
port.

3
Installation
This chapter describes how to install the DECrepeater 90C as a
standalone unit or in a DEChub 90 Ethernet backplane. You can install a
standalone unit on a table or wall.
To install the repeater on a table or wall, see the ‘‘Standalone Installation’’
section.
To install the repeater in a DEChub 90 Ethernet backplane, see the
‘‘Backplane Installation’’ section.

Standalone Installation
To install the DECrepeater as a standalone unit on a table or wall,
perform the following procedures:

Select a location.
The location should have access to a power outlet that supplies the correct
voltage.

Place the repeater on a table.
When you pale the DECrepeater 90C on a table top, your only
requirement is to follow the environmental specifications found in
Appendix A.

3–1

3–2 Installation

Mount the repeater on a wall.
1. Remove the back cover of the repeater (if necessary).
a. Insert a small screwdriver into the top mounting hole on the cover.
b. Lift the internal latch with the screwdriver, then pull the cover
away and down from the top of the repeater.

LJ-00320-TI0

2. Use the mounting holes on the cover to determine a position for the
mounting screws on the wall.
3. Secure the back cover to the wall using the mounting screws.
The screws should be tight enough to to provide some resistance if
you try to remove the back cover from the wall. Do not make them so
tight that the cover is distorted or cannot be removed from the wall.
4. Remove the back cover from the wall.

Installation 3–3

LJ-00701-TI0

5. Attach the back cover to the repeater.
6. Mount the repeater onto the mounting screws.

3–4 Installation

Connect the cables.
Refer to the following figure to perform these steps.
1. Connect the cable from the power supply to the 7-pin power connector
on the DECrepeater 90C. Align the power symbol on the dc power
connector with the power symbol on the DECrepeater 90C and push
straight in.
2. Connect the DECrepeater 90C to the power supply.
•

For a 240-volt power outlet, connect the power supply cord to
the modular power supply. Then plug the other end of the power
supply cord into the 240-volt power outlet.

•

For a 120-volt power outlet, plug the modular power supply
directly into the 120-volt outlet.

3. All the LED indicators should turn on during initial power-up. After
approximately 0.5 seconds, the network activity LED should turn off
while the other LEDs remain on.
4. Connect the Ethernet ThinWire T-connector to the port 0 BNC
network connector. Terminate the connection with a 50-ohm
terminator or extend the Ethernet segment to the next device.
5. The port 0 status activity LED should be on or flashing to indicate the
amount of network traffic. The LED intensity varies.
6. Connect ThinWire Ethernet cables to ports 1 through 6. Do not use
T-connectors. These ports have built-in terminators.

Install and verify devices.
1. Connect devices to ports 1 through 6, using correctly terminated
ThinWire segments.
A port LED should turn on when the port is correctly terminated and
first receives network activity.

Installation 3–5

2. Verify the operation of each device by sending information to the port
being tested.
The DECrepeater 90C is now installed.
50-O hm
T erminator
T -Connector

T -Connector

50-O hm
T erminator
PC
or
Workstation

LJ-00939-TI0

3–6 Installation

Backplane Installation
To install the repeater in the DEChub 90 Ethernet backplane, perform
the following procedures:

Remove the back cover.
Remove the back cover if one is present.
1. Insert a small screwdriver into the top mounting hole on the cover.
2. Lift the internal latch with the screwdriver, then pull the cover away
and down from the top of the repeater.

LJ-00320-TI0

Installation 3–7

Mount the repeater in the backplane.
1. Install the repeater in the backplane as shown in the following figure.
Place the lower mounting tab, on the back of the DECrepeater 90C, in
the correct mounting slot on the backplane.
2. Rock the repeater into place. You hear an audible click when the
repeater securely latches in place.

LJ-00954-TI0

3–8 Installation

NOTE
The DECrepeater 90C can be installed into or removed from
the DEChub 90 Ethernet backplane while power is applied to
the backplane (hot swap).
3. If this is a new installation, supply power to the backplane.
4. All LEDs on the repeater turn on either immediately or at initial
power-up. After approximately 0.5 seconds, the port 0 status LED and
port status LEDs turn on with intensity proportional to the amount of
activity on the indicated port.
NOTE
The port status LEDs for unconnected ports should turn off
when network traffic is established.

Install and verify devices.
1. Connect the desired devices to ports 1 to 6, using correctly terminated
ThinWire segments. The corresponding port LEDs should turn on.
2. Verify the operation of each device you plan to use by connecting and
sending information to each port you have connected.
The DECrepeater 90C is now installed.

4
Management
This chapter provides information on managing the DECrepeater 90C
on a network or in a standalone configuration. The chapter describes
available functions and commands, how to access the maintenance
operations protocol (MOP), management techniques, and messages.

Managing the DECrepeater 90C
When you install the DECrepeater 90C in a DEChub 90 Ethernet
backplane, you can manage the repeater by using a DECbridge 90 work
group bridge. All commands that affect the DECrepeater 90C are part of
the DECbridge 90 command set.

Functions
Online management allows you to perform the following functions on the
DECrepeater 90C:
•

Identify all repeaters in the DEChub 90.

•

Examine the port status (enabled, disabled, properly operating, or
inoperative) of repeater ports that share the DEChub 90 backplane
with a bridge.

•

Examine the work group address database entries 1 to 200, annotated
with the repeater port to which each is attached, if any.

•

Reset any repeater in the DEChub 90 backplane.

•

Enable or disable a repeater port.

•

Define the bridge password.

See the ‘‘Command Descriptions’’ section for information on command
syntax.

4–1

4–2 Management

Components Needed
You need the following components to manage a DECrepeater 90C online:
•

DEChub 90 backplane

•

DECbridge 90 work group bridge

•

DECrepeater 90C

Accessing the MOP from VMS
On a VMS operating system, the MOP console carrier is included as part
of the network control program (NCP) facility, which requires a DECnet
license.
You do not need increased user privileges to use NCP. To establish a
console carrier session, you must know
•

The Ethernet address of the bridge to be managed

•

The Ethernet name of the circuit that contains the bridge

The circuit name is needed because a VMS operating system may have
more than one Ethernet interface. The Ethernet address should be on
the label on the DECbridge 90 front panel. The following Ethernet circuit
names, based on system type, apply:
System

Ethernet Circuit Name

VAX 6000 and VAX 9000 XMI
computers

MNA-0

BI-based systems (VAX 6300 and
VAX 6400 computers)

BNA-0

VAX 4000 computer series

ISA-0

MicroVAX/3600/3900

QNA-0

VAXstation 2000 and 3000
computer series

SVA-0

VAX–11/780 and VAX–11/785
computers (UNIBUS)

UNA-0

Management 4–3

Example
Here is a typical VMS command to establish a session from a VAXstation
3100, using a bridge address of 08-00-2B-01-23-45 and the Ethernet
circuit name SVA-0:
$ MCR NCP CONNECT VIA SVA-0 PHYSICAL ADDRESS 08-00-2B-01-23-45

When you establish the connection, the screen displays the following:
Console connected (press CTRL/D when finished)

Accessing a Bridge Repeatedly
If you need to access a specific bridge repeatedly, you can enter the
Ethernet address for it in the NCP database. This is usually done by
choosing an arbitrary address in area 13. Bridge names in the NCP
database can have a maximum of six characters.
Example:
If you call your bridge DBRG1 on address 13.87 and access it from a
VAX 6400 (Ethernet circuit name BNA-0), you could use the following
commands:
$ NCP
NCP> DEFINE NODE DBRG1 ADDRESS 13.87 HARDWARE 08-00-2b-01-23-45
SERVICE CIR BNA-0
NCP> SET NODE DBRG1 ALL

To access the bridge, type:
$ NCP CONNECT NODE DBRG1

Accessing the MOP from ULTRIX
On ULTRIX operating systems, the console carrier is a separate utility
included as part of the MOP option. The option is part of the regular
distribution, but is not selected by default and is not included in the basic
installation. You can install MOP from the original distribution media by
using the setld utility. You must be have superuser privileges to invoke
the console carrier.
After the MOP option is installed, each bridge to be managed must be
given a name and a dummy node number, using the addnode utility. For
example:
# addnode 13.1 DBRG1

4–4 Management

After the name and node number is assigned, you can establish the link
at any time by using the ccr command:
#

ccr -n DBRG1 -h 08-00-2b-01-23-45 -c sva-0

In this example, the -h qualifier is followed by the station address of the
DECbridge unit to be attached. The -c qualifier is followed by the name
of the Ethernet circuit to use for the connection. The following Ethernet
circuit names, based on system type, apply:
System

Ethernet Circuit Name

VAX 6000 and 9000 XMI computers

mna-0

BI-based systems (VAX 6300 and
VAX 6400 computers)

bna-0

VAX 4000 computer series

isa-0

MicroVAX/3600/3900

qna-0

VAXstation 2000 and 3000
computer series

sva-0

VAX–11/780 and VAX–11/785
computers(UNIBUS)

una-0

Console Carrier User Interface
The DECbridge 90 is not shipped with a preset password, so no password
prompt displays when you connect for the first time. For secure operation
of the DECbridge 90, you should define a password using the DEFINE
BRIDGE PASSWORD command.
The password prompt is represented by the pound sign (#). If you do not
define a password, the password prompt does not display when you log in.
You have three attempts to enter a password; if all three attempts fail,
you must disconnect and try again.
After you enter the correct password, or if there is no password, the
DECbridge console carrier management banner and prompt display on
the screen:
Copyright © Digital Equipment Corporation 1991.
DECbridge 90 V1.0 25-JAN-1991 08-00-2B-01-23-45
Flash EPROM V1.0 31-JAN-1991
DECbridge>

Management 4–5

Console Carrier Command Language
You can type a question mark (?) at any point in the command line to
display a list of the options available at that point in the command line.
The system accepts unique abbreviations of commands.
Table 4–1 summarizes the DECbridge commands that apply to the
DECrepeater 90C. For a complete list of commands, see the DECbridge
90 Owner’s Manual.
Table 4–1 Summary of DECrepeater 90 Commands
Command

Argument and Parameter

DEFINE1

BRIDGE HUB_MANAGEMENT
ENABLE
DISABLE
BRIDGE PASSWORD password string

LIST

BRIDGE

SET

BRIDGE HUB_MANAGEMENT
ENABLE
DISABLE
PORT [hub number,] slot number, port number
ENABLE
DISABLE
REPEATER [[hub number,] slot number RESET

SHOW

ADDRESS [start index,[stop index]]
PORT [hub number,] slot number, port number
REPEATER [[hub number,] slot number]

1 The DEFINE commands change only the default settings that are invoked at power-up or
a reset. DEFINE commands do not change the currently active values, with the exception
of DEFINE BRIDGE PASSWORD. DEFINE BRIDGE PASSWORD takes effect immediately.
The SET commands change only the currently active values, but do not affect the
defaults that are invoked at power-up or a reset.

4–6 Management

Command Parameters
A start index or stop index for an address is a decimal index into the work
group forwarding database in the range of 1 to 200.
A slot number is a number from 1 through 8 that identifies a hub slot
containing a DECrepeater 90.
If two DEChub units are connected together, the hub number (1 or 2) is
specified before the slot number. For example:
2,4 refers to the fourth slot from the left in the second DEChub,

which is the hub that does not contain the DECbridge 90.
A password string is a string of a maximum of 16 characters.

A port number is either a DECbridge 90 port, or the number of a port on
a DECrepeater installed in the DEChub backplane that has the bridge.
The DECbridge backbone port is the single digit 1. The work group port
is 2. A repeater port is identified by a hub number as just described, and
the port number within the slot (0 to 8). For example:
2,4 refers to the fourth port on a repeater in slot 2, in the same hub
as the DECbridge 90.
2,4,1 refers to the first port on a repeater in the fourth slot of the
second hub.

Command Descriptions
The command examples are based on the sample configuration in
Figure 4–1.
DEFINE BRIDGE HUB_MANAGEMENT DISABLE
SET BRIDGE HUB_MANAGEMENT DISABLE
Disables all repeater management through the DECbridge 90 unit for
DECrepeater 90 units in the DEChub 90 backplane. When management
is disabled, you will get an error with the SHOW REPEATER, SET PORT
or SHOW PORT commands on repeater ports, and you will not get port
number information from the SHOW ADDRESS command.

DEFINE BRIDGE HUB_MANAGEMENT ENABLE
SET BRIDGE HUB_MANAGEMENT ENABLE
Reverses the effect of the SET or DEFINE BRIDGE HUB_
MANAGEMENT DISABLE commands.

Management 4–7

DEFINE BRIDGE PASSWORD password string
Lets you changes the password string. You are prompted twice for a
new password. The password may be up to 16 characters long and is
not displayed on the screen. The new password is saved. There is no
corresponding SET command because the DEFINE BRIDGE PASSWORD
takes effect immediately.
MOP provides a mechanism for setting and checking passwords. This
mechanism is only intended to provide protection against accidental
tampering with parameters and is not intended as a security feature. No
attempt is made to prevent compromise of the password by malicious
users. The DECbridge 90 should not be used in applications that
absolutely depend on the prevention of any unauthorized modifications to
the parameters.

LIST BRIDGE
Displays the nonvolatile bridge-wide parameters.

SET PORT [hub number,] slot number,port number DISABLE
Disables the attachment of a specific repeater port in the DEChub
backplane. The port status indicator on the selected DECrepeater 90 will
flash, indicating that the port was disconnected by the network manager.
There is no equivalent DEFINE command for disabling repeater ports.
Example: The expected response to a SET PORT DISABLE command is
shown.
DECbridge> SET PORT 1,3,2 DISABLE
Hub 1 slot 3 port 2 segment counter 0 status: disabled

SET PORT [hub number,] slot number, port number ENABLE
Reverses the effect of SET PORT DISABLE for DECrepeater 90 ports.

4–8 Management

Example: The expected response to a SET PORT ENABLE command is
shown.
DECbridge> SET PORT 1,3,2 ENABLE
Hub 1 slot 3 port 2 segment counter 0 status: no carrier loopback

SET REPEATER [hub number,] slot number RESET.
Resets a specific repeater. There is no output response to this command.
All disabled ports are enabled.
SHOW ADDRESS [start index,[ stop index]]
Displays the station address for the selected range of entries in the
address database. All addresses in this database are in the work group.
The indexes range from 1 to 200. The start index is always displayed, but
other entries in the range are only displayed if they are not empty. If you
omit indexes, the command displays the addresses of all stations in the
work group.
When the DECbridge 90 is used with the DECrepeater 90C or 90T,
this commands also displays the hub slot number and repeater port
that each station is attached to. It may take several minutes for the
SHOW ADDRESS command to accurately reflect the correct repeater port
number for stations recently added to the network or moved from one port
to another. See Appendix C for further details on SHOW ADDRESS.
Example: All addresses contained within the hub configuration are
shown. Addresses 5 and 7 display the same hub, host, and port because
both devices are daisy-chained on the same port.
DECbridge> SHOW AD
Address 1: 08-00-2B-0F-19-23
Address 2: 08-00-2B-10-20-30 hub 2 slot 8 port 4
Address 5: 08-00-2B-10-6A-31 hub 2 slot 3 port 3
Address 6: 08-00-2B-A6-43-17 hub 1 slot 3 port 5
Address 7: 08-00-2B-16-23-4C hub 2 slot 3 port 3

Example: The expected response of a SHOW ADDRESS command to a
nonexistent address is shown.
DECbridge> SHOW AD 3
Address 3: unused address

Management 4–9

Example: The expected response of a SHOW ADDRESS command to a
valid address is shown.
DECbridge> SHOW AD 2
Address 2: 08-00-2B-10-20-30 hub 2 slot 8 port 4

Example: The expected response of a SHOW ADDRESS command for a
range of address is shown.
DECbridge> SHOW AD 2,6
Address 2: 08-00-2B-10-20-30 hub 2 slot 8 port 4
Address 5: 08-00-2B-10-6A-31 hub 2 slot 3 port 3
Address 6: 08-00-2B-A6-43-17 hub 1 slot 3 port 5

SHOW PORT [hub number,] slot number, port number
Shows whether the port is enabled or disabled and lists the operating
status of the port. The hub number may be 1 or 2, and the slot numbers
may be 1 to 8. For the DECrepeater 90C, port numbers are 1 to 6.
Example: The expected response to a SHOW PORT command is shown.
The hub was not defined in the command, so the default (1) was used.
DECbridge> SHOW PORT 3,2
Hub 1 slot 3 port 2 segment counter 0 status: disabled-no
carrier loopback

Example: A SHOW PORT command for hub 2 is shown.
DECbridge> SHOW PORT 2,3,2
Hub 2 slot 3 port 2 segment counter 0 status: operational

SHOW REPEATER [[hub number,] slot number]
Shows the type of repeater and the port status for each port on that
repeater. The hub number may be 1 or 2, and slot numbers may be 1 to 8.
If you do not include parameters, the command displays information for
all repeaters in both hubs.
Example: The expected response of a SHOW REPEATER command
is shown. Note that DECrepeater 90T and DECrepeater 90C units are
installed in the hub.
DECbridge> SHOW REP
Hub 1 slot 3 twisted pair repeater, rev.1, 8 ports.
Hub 1 slot 4 ThinWire repeater, rev.1, 6 ports.
Hub 2 slot 3 ThinWire repeater, rev.1, 6 ports.
Hub 2 slot 6 twisted pair repeater, rev.1, 8 ports.
Hub 2 slot 8 twisted pair repeater, rev.1, 8 ports.

4–10 Management

Example: The response to a SHOW REPEATER command to a slot that
contains a device other than a repeater is shown.
DECbridge> SHOW REPEATER 1
No repeater responds.

Example: The response to a SHOW REPEATER command to an empty
slot is shown.
DECbridge> SHOW REPEATER 7
No repeater responds.

Example: The response to a SHOW REPEATER command for a
particular repeater is shown.
DECbridge> SHOW REP 3
Hub 1 slot 3 twisted pair, rev.1, 8 ports.
Hub 1 slot 3 port 0 segment counter 0 status: operational
Hub 1 slot 3 port 1 segment counter 1 status: no carrier loopback
Hub 1 slot 3 port 2 segment counter 0 status: disabled
Hub 1 slot 3 port 3 segment counter 0 status: operational
Hub 1 slot 3 port 4 segment counter 1 status: no carrier loopback
Hub 1 slot 3 port 5 segment counter 1 status: no carrier loopback
Hub 1 slot 3 port 6 segment counter 1 status: no carrier loopback
Hub 1 slot 3 port 7 segment counter 1 status: no carrier loopback
Hub 1 slot 3 port 8 segment counter 1 status: no carrier loopback

Example: The response to a SHOW REPEATER command for hub 2, slot
3 is shown.
DECbridge> SHOW REP 2,3
Hub 2 slot 3 ThinWire, rev.1, 6 ports.
Hub 2 slot 3 port 0 segment counter 0 status: operational
Hub 2 slot 3 port 1 segment counter 1 status: no carrier loopback
Hub 2 slot 3 port 2 segment counter 1 status: no carrier loopback
Hub 2 slot 3 port 3 segment counter 1 status: no carrier loopback
Hub 2 slot 3 port 4 segment counter 1 status: no carrier loopback
Hub 2 slot 3 port 5 segment counter 0 status: operational
Hub 2 slot 3 port 6 segment counter 1 status: no carrier loopback

Example: The response to a SHOW REPEATER command when the
DECbridge 90 is not the hub manager or the DECbridge 90 is still in
the power-up stage is shown. After power-up, there is a 60-second delay
before the DECbridge takes control of the hub.
DECbridge> SHOW REP
The DECbridge 90 is not the designated hub manager.

Management 4–11

Typical Management Techniques
You can manage a DECrepeater 90C as a standalone unit or within a
group of repeaters in a DEChub 90 backplane. For a standalone unit, you
refer to the DECrepeater 90C LEDs for system status. In a DEChub 90
environment, you can refer to the LEDs and perform online management
by using a DECbridge 90 work group bridge.
Whether you use a standalone or DEChub 90 configuration, Digital
recommends that you create a network topology map. This map makes it
easier to perform management tasks. Figures 4–2 and 4–3 show typical
topology maps.

Remote Network Management With the DECbridge 90
You can manage a DECrepeater 90C remotely, through a DECbridge
90 work group bridge and a DEChub 90 backplane. The DECbridge 90
communicates across the DEChub 90 backplane to any DECrepeater in
the DEChub 90. You can connect two DEChub 90 backplanes together
and manage the repeaters in both DEChub 90s with one DECbridge 90.
The DECbridge 90 communicates with the DECrepeater 90C by using
private signals on the DEChub backplane. The two DEChub 90 units are
connected by two cables:
•

ThinWire coaxial cable, to carry the work group Ethernet signals

•

DECconnect office cable, to carry the management signals

NOTE
If two DEChub backplanes are being managed by one bridge, the
backplanes must be connected with ThinWire cable (BNC to BNC)
(PN BC16M–xx) and a DECconnect office cable (PN BC16E–xx ).
Management Disconnect
A port can be partitioned at any time by the management protocol. The
management protocol can only be used for the repeater ports mounted
in the DEChub 90 backplane and connected to a DECbridge 90. When a
port is disconnected by the management protocol, it can be reconnected by
either turning the power off and on again, or by using the management
protocol. If a port is partitioned by the management protocol, the port
LED flashes approximately twice a second.

4–12 Management

DECserver
90L
08-00-2B-0F-19-23

DECBridge 90
08-00-2B-1D-07-21
1

DECrepeater
90T

H4005

P ower
S upply

DECrepeater
90C

AUI
Cable

VT420

Thinwire
Cable

Disk Server

MMJ
Cable

08-00-2B-A6-43-17

DECrepeater
90C
P ower
S upply

DECrepeater
90T

08-00-2B-10-6A-31

08-00-2B-16-23-4C

08-00-2B-10-20-30
LJ-00947-TI0

Figure 4–1

Sample Configuration and Topology Map

Whether your configuration is a standalone or a DEChub 90, you should
create a network topology map. The map helps facilitate management
tasks.

Management 4–13

DEChub 90
Slot 1

DECrepeater 90T

Slot 2

DECrepeater 90C

Slot 8

DECBridge 90

Port 1

Node - Address - Username

Port 1

Node - Address - Username

Port 1

Address

Port 2

Node - Address - Username

Port 2

Node - Address - Username

Port 2

Address

Port 3

Node - Address - Username

Port 3

Node - Address - Username

Port 3

Address

Port 4

Node - Address - Username

Port 4

Node - Address - Username

Port 4

Address

Port 5

Node - Address - Username

Port 5

Node - Address - Username

Port 5

Address

Port 6

Node - Address - Username

Port 6

Node - Address - Username

Port 6

Address

Port 7

Node - Address - Username

Port 7

Node - Address - Username

Port 7

Address

Port 8

Node - Address - Username

Port 8

Node - Address - Username

Port 8

Address
LJ-00956-TI0

Figure 4–2

Typical Network Topology Map

Management Session
To perform online management commands, you establish a MOP console
carrier session with the bridge from any remote node.
After you connect to the bridge, the following prompt displays:
DECbridge>

When a bridge goes through a power cycle or is reset, the bridge begins
to poll repeaters for status. This process includes a special algorithm
to determine which repeater ports have stations attached. The time to
complete this algorithm depends on the number of repeaters and amount
of network activity. You should allow time for this process to complete
before proceeding to manage the hub. For the same reason, it may take
time for the system to report on stations or repeaters that are moved in
the hub. See Appendix C for more details.
Example of a typical management session
1. Determine what repeaters are in the hub.
DECbridge> SHOW REPEATER
Hub 1 slot 5 ThinWire repeater, rev.0, 6 ports.

In this example, there is a ThinWire repeater (DECrepeater 90C) in
the same hub as the bridge (hub 1), if this is a 2-hub configuration.
The repeater is in slot 5 of the hub and has 6 ThinWire ports.

4–14 Management

2. Determine what stations are connected to the repeaters in the hub.
DECbridge> SHOW ADDRESS
Address 1: 08-00-2B-19-94-FB
Address 2: 08-00-2B-1E-2D-0C hub 1 slot 5 port 3

This example indicates that a station with address 08-00-2B-1E-2D-0C
is connected to the repeater in slot 5, on port 3. At this point, without
physical examination, you have enough information to construct a
network map.
If Problems Are Reported
If a problem is reported, there are a number of useful commands
available. Using the previous sample management session, you can
determine which repeater and port connects the user’s station.
Enter the following command to display the status of all ports on the
repeater in slot 5:
DECbridge> SHOW REPEATER 5
Hub 1 slot 5 ThinWire, rev.1, 6 ports.
Hub 1 slot 5 port 0 segment counter 0 status: operational
Hub 1 slot 5 port 1 segment counter 0 status: excessive collisions
Hub 1 slot 5 port 2 segment counter 0 status: excessive length collision
Hub 1 slot 5 port 3 segment counter 0 status: operational
Hub 1 slot 5 port 4 segment counter 0 status: excessive length collision
Hub 1 slot 5 port 5 segment counter 0 status: excessive length collision
Hub 1 slot 5 port 6 segment counter 0 status: excessive length collision

The following table lists the possible status messages and their most
common causes.
Message

Most Common Cause

Operational

Cable is connected, everything is okay.

Excessive length collision
or
Excessive collisions

Cable fault, usually a port that is not
connected to anything or an unterminated
cable.

No carrier loopback
or
Transmit carrier drop out

Cable fault, usually a shorted cable.

Jabber

Station(s) connected to this port continue
to transmit, expect a faulty station.

Management 4–15

The operational condition is normal. All other conditions cause the
repeater to automatically partition the port. When the condition
clears, the repeater automatically reconnects the port and reports it
as operational again.
To help solve intermittent problems, the repeater reports a segmentation
count. This count runs from 0 to 15, then latches at 15. Every time you
use the SHOW REPEATER command, this count is set to zero.
If this count is not zero, you can tell that a port has partitioned since
the last SHOW REPEATER command. This partitioning is normal
when users turn stations on and off, or when cables are connected or
disconnected from the repeater during installation and reconfiguration.
If none of these normal causes have occurred, you should suspect an
intermittent problem with cabling or attached stations.
Other Commands
There are two more commands that are useful in managing repeater
networks.
DECbridge> SET PORT 5,1 DISABLE
Hub 1 slot 5 port 1 segment counter 0 status: disabled-no carrier loopback

This command allows the manager to disable a particular port on a
repeater. This command may be useful if stations attached to the port are
causing network difficulties.
DECbridge> SET REPEATER 5 RESET

This command resets the repeater to the power-up condition. This
includes restoring any ports that were partitioned by the manager and
resetting the segmentation counters.

4–16 Management

Messages
Table 4–2 describes DECbridge 90 messages that apply to the
DECrepeater 90C. For a complete list of messages, see the DECbridge
90 Owner’s Manual.
Table 4–2 DECbridge 90 Messages
This message . . .

Indicates that . . .

Address n: unused
address

Address number n does not contain a station address.

Confirmation error
- password not
changed.

The second entry or verification of a new password given
in a DEFINE BRIDGE PASSWORD command did not
match the first entry.

DECbridge 90 is not
the designated hub
manager

The DECbridge 90 was not the designated hub manager
when the SHOW PORT or SHOW REPEATER command
was issued. This occurs when
•

The bridge is reset, and the DECbridge is not the
hub manager for 60 seconds.

•

Another DECbridge unit is acting as the current
hub manager.

•

A fault exists in one of the following, preventing
management communication:
— In the MMJ cable or connections between two
DEChub backplanes
— In the power supply of one of the DEChub units
— In the serial port transceivers in the DEChub
90

Hub management
disabled

A SHOW PORT or SHOW REPEATER command was
issued to a DECbridge 90 that has repeater management
disabled. Enable repeater management with the SET
BRIDGE HUB_MANAGEMENT ENABLE command
before trying again.

Management 4–17

Table 4–2 (Cont.) DECbridge 90 Messages
This message . . .

Indicates that . . .

Hub number and slot
number [ [hub], slot].
Hub is 1 or 2, slot is
1-15

One or more parameters in a SHOW REPEATER
command were out of range. The hub number must
be 1 or 2. The slot number must be from 1 to 15.

Hub h slot s - port
number out of range

The port number in a SHOW PORT command was out
of range for the device in hub n slot s. Use the SHOW
REPEATER command to determine the number of ports
for the device, and to specify a port number within that
range.

Hub h slot s not a
repeater

The device does not use the same management protocol
as the DECrepeater 90C and 90T. The device’s ports, if
any, cannot be managed by the DECbridge 90.

Hub h slot s
unrecognized type

The repeater type in hub h slot s is not known to
the DECbridge 90, but the repeater ports can still be
managed with the DECbridge 90.

No repeater responds

There is no repeater installed in the requested hub slots,
or the repeater is not functioning.

No such port

The bridge port number in a SHOW PORT command
was invalid. Valid numbers are 1 and 2.

Password too long not changed

A password in a DEFINE BRIDGE PASSWORD
command was more than 16 characters.

Port number
[[hub,]slot,]port

One of the parameters in a SET PORT or DEFINE
PORT command was not a valid hub, slot, or port
number.

Station address
number [first [,last] ]
in range 1-200

One or more parameters in a SHOW ADDRESS
command was out of the valid range of 1 to 200.

???

A command or parameter was not recognized. Type ? to
display valid commands.

180501

A loopback diagnostic has run and passed on the
backbone port. If the backbone port is not receiving
any messages, this diagnostic is run every 10 minutes.

4–18 Management

Table 4–2 (Cont.) DECbridge 90 Messages
This message . . .

Indicates that . . .

180201

A loopback diagnostic has run and passed on the work
group port. If the work group port is not receiving any
messages, this diagnostic is run every 10 minutes.

1805:00-00-00-00
01

A loopback diagnostic has run and failed on the
backbone port. The diagnostic is retried every 5 seconds
until the test passes.

1802:00-00-00-00
01

A loopback diagnostic has run and failed on the work
group port. The diagnostic is retried every 5 seconds
until the test passes.

Standalone Configuration Management
The recommended process for managing a small stand-alone network is:
•

Maintain records indicating which stations are connected to each port
on each repeater. Digital recommends drawing a network topology
map.

•

Observe the LEDs on the DECrepeater to determine the network
status.

Figure 4–3 shows a typical standalone network topology map. Table 4–3
describes each LED and its function.
DECrepeater 90C
Port 1

Node - Address - Username

Port 2

Node - Address - Username

Port 3

Node - Address - Username

Port 4

Node - Address - Username

Port 5

Node - Address - Username

Port 6

Node - Address - Username
LJ-01054-TI0

Figure 4–3

Typical Standalone Topology Map

Management 4–19

Note on LED Sequence After Power-Up
After you power up a standalone DECrepeater 90C, all LEDs except
the network activity LED remain on until an active connection, either
hardware or network activity. This is a normal condition. After an active
station is connected to one of the ports, the LED for the active port
remains on and all other port LEDs turn off.
Table 4–3 DECrepeater 90C Status LEDs
Power indicator—Monitors the status of the +5.0 Vdc voltage.
On: The +5.0 Vdc voltage is normal.
Off: The voltage is abnormal (as in a power failure.)
Network activity indicator—Monitors the network activity.
On: There is network activity.
Off: There is no network activity.
Port 0 status indicator—Monitors the status of the ThinWire input
to the repeater.
On: Port 0 is functional.
Off: Port 0 has failed or has been partitioned.
Flashing: The port has been partitioned by management.
Port 1 to 8 status indicators— Monitor the activity of each port.
The top LED represents port 1, and the bottom LED represents port 6.
On: The port has a connection.
Off: The port does not have a connection or has been partitioned.
Flashing: The port has been partitioned by management.

5
Troubleshooting
This chapter provides troubleshooting information for the DECrepeater
90C when used as a standalone unit or when installed in the DEChub 90
backplane.
Before You Start
1. Verify the installation of the repeater The installation must meet the
configuration rules in Chapter 2.
2. Note the fault condition.
3. Isolate the problem.
Use Table 5–1 to troubleshoot a standalone DECrepeater 90C. Use
Table 5–2 to troubleshoot a DECrepeater installed in a DEChub 90
configuration.

5–1

5–2 Troubleshooting

DECrepeater 90C Standalone Troubleshooting
Use Table 5–1 to troubleshoot a standalone DECrepeater 90C.
Table 5–1 Troubleshooting a DECrepeater 90C Standalone Unit
If...

Then...

Do this...

All LEDs are off.

Check the ac power
connection.

Check that the power supply
is properly plugged into the
power outlet. Check the power
to the power outlet.

Check the power
supply.

Check the 7-pin connector
to the power supply. If the
connections are okay, replace
either the power supply (for
120 V operation) or both the
power supply cord and power
supply (for 220 V operation).

There is low network
activity or no
network activity.

Ensure that network activity is
present.

If the network
activity LED still
fails to turn on,

Turn the unit off and on by
unplugging and replugging
the power supply in. Check
that the network activity LED
turns on momentarily.

If the network
activity LED turns
on momentarily, the
network activity
LED portion of
testing has passed.
If the network LED
still fails to turn on,
the DECrepeater
90C is defective.

Replace the DECrepeater 90C.

Ensure that the
cable has activity on
it. If the LED still
fails to turn on, the
port is defective.

Switch to an unused port or
replace the DECrepeater 90C.

The network activity
LED is off.

The port status LED
is off.

Troubleshooting 5–3

Table 5–1 (Cont.) Troubleshooting a DECrepeater 90C Standalone Unit
If...

Then...

Do this...

All port LEDs are
off.

A connection has not
been made.

Remove all network
connections (items 5 and 6 ).
Turn the repeater off and on
by unplugging and replugging
the power supply. All LED
indicators turn on. Only the
network activity LED turns
off.

If any LED other
than the network
activity LED turns
off, the DECrepeater
90C has failed this
part of the self-test.

Replace the DECrepeater 90C.

If all LEDs except
the network activity
LED are on, this
portion of the selftest has passed.

Connect a known active
ThinWire network segment
to the repeater. The status
LED for the connected port
stays on, while all status LEDs
for the unconnected ports
should turn off as soon as the
first connection is made to the
active segment.

If the status LED
for the connected
port stays on and the
status LED for the
unconnected ports
stay off, then the
connected port is
okay.

Continue installing the other
network cables for each port
that you are going to use.

If the status LED
for the unconnected
ports do not turn off
while the LED for
the connected port
remains on, there is
a possible problem
with the cable or
port.

Try another port. If the same
condition continues, check for
a cable problem by connecting
a good cable with a good device
at the other end.

5–4 Troubleshooting

Table 5–1 (Cont.) Troubleshooting a DECrepeater 90C Standalone Unit
If...

Then...

Do this...

If the same condition
exists when a good
cable is plugged in,
the DECrepeater
90C is defective.

Replace the DECrepeater 90C.

Continue installing
other network cables
for each port you are
going to use.

The indicator LED for each
properly terminated port
should turn on.

If the LED for each
properly terminated
port remains off
when a cable is
connected, the
DECrepeater 90C
is defective.

Replace the DECrepeater 90C.

Troubleshooting 5–5

1
2
3

LJ-00544-TI0

5–6 Troubleshooting

DECrepeater 90C Backplane Configuration
Troubleshooting
Use Table 5–2 to troubleshoot a DECrepeater installed in a DEChub 90
configuration.
Table 5–2 Troubleshooting a DECrepeater 90C in a DEChub 90
Backplane
If...

Then...

Do this...

The power LED is
off.

The DECrepeater
90C is not receiving
+5 V.

Check the power LED on the
DEChub 90 power supply.

If the power LED
on the DEChub 90
is off, there is a
problem with the
DEChub 90 power
supply.

See the troubleshooting
procedures in the DEChub90
Owner’s Manual.

If the power LED
on the DEChub 90
power supply is on,
are the power LEDs
on other components
off? If other
components are
on, the DECrepeater
90C has a power
problem.

Try reseating the DECrepeater
90C in either the same slot or
another slot.

If the power LED
on the DEChub 90
power supply is on,
are other component
power LEDs off? If
other components
are off, the DEChub
90 has a power
problem.

See the troubleshooting
procedures in the DEChub
90 Owner’s Manual.

Troubleshooting 5–7

Table 5–2 (Cont.) Troubleshooting a DECrepeater 90C in a DEChub 90
Backplane
If...

The port 0 network
activity LED is off.

The port 0 network
activity LED is on.

Then...

Do this...

If the power LED
turns on when
reseated in the
same slot, the
DECrepeater 90C
was not properly
seated.

Make sure the DECrepeater
90C is properly seated in the
slot.

If the power LED
turns on when
reseated in another
slot, the problem is
with the DEChub 90.

See the troubleshooting
procedures in the DEChub
90 Owner’s Manual.

If the DECrepeater
90C does not turn on
in a known good slot,
the DECrepeater
90C is defective.

Replace the DECrepeater 90C.

The DECrepeater or
any other unit in the
DEChub 90 may not
be connected to an
active segment.

Connect a known active
segment to any unit in the
DEChub 90.

If the DECrepeater
90C is connected
to a known active
segment and the port
0 LED is off. The
DECrepeater 90C is
defective.

Replace the DECrepeater 90C.

This portion of
the self-test ran
successfully.

Check that the LED for each
port with a connected cable is
on.

If the LED for the
connected cable is
off, the DECrepeater
90C does not
acknowledge the
connection to its
port.

Check that the cable is
properly terminated at the
other end.

5–8 Troubleshooting

Table 5–2 (Cont.) Troubleshooting a DECrepeater 90C in a DEChub 90
Backplane
If...

Then...

Do this...

If the cable is not
connected at the
other end.

Connect the other end of this
cable and terminate.

If the cable is
connected at other
end, the cable may
not be continuous.

Check the cable for continuity.

The cable may be
defective.

Replace with a known good
cable.

If the cable is
continuous, the
cable may not be
properly terminated.

Properly terminate the cable.

If the port LED
turns on, the port is
okay.

No action is required.

If the port LED
remains off, test the
failing port.

Remove the cable from failing
port and replace with a 50-ohm
terminator.

If the port LED
remains off, the
DECrepeater 90C is
defective.

Replace the DECrepeater 90C.

A
DECrepeater 90C Specifications
This appendix provides the following specifications for the DECrepeater
90C:
•

Physical dimensions

•

Environmental specifications

•

Electrical specifications

•

Parts list

Physical Dimensions
Dimension

Measurement

Height

3.5 cm ( 1.4 in)

Width

28.0 cm ( 11.0 in)

Depth

14.0 cm ( 5.5 in)

Weight

0.77 kg ( 1.7 lb)

A–1

A–2 DECrepeater 90C Specifications

Environmental Specifications
The DECrepeater 90C is designed to operate in an office environment
or equipment room environment such as telephone closets or satellite
equipment rooms. It is not intended to operate in an air plenum.

Operating Environment
Condition

Value

Temperature

5°C to 50°C (41°F to 122°F)

Maximum rate of
change

20°C/hr (36°F/hr)

Relative humidity

10% to 95% (noncondensing)

Wet-bulb
temperature

32°C ( 90°F) maximum

Dew point

2°C (36°F) minimum

Altitude

Sea level to 2.4 km (8000 ft)

Air flow

Convectively cooled. A minimum of 10 cm (4 in) of
space must be provided on both ends of the repeater for
adequate air flow.

Shipping Environment Specifications
Condition

Value

Temperature

-40°C to 66°C (-40°F to 151°F)

Relative humidity

10% to 95% (non-condensing)

Altitude

Sea level to 4.9 km (16,000 ft)

DECrepeater 90C Specifications A–3

Electrical Specifications
The DECrepeater 90C features either a self-contained power supply or
self-contained power supply and power cord option.

Power Supply
Specification

Value

Voltage (domestic)

104 Vac to 128 Vac ( nominal 120 Vac)

Voltage (international)

208 Vac to 256 Vac (nominal 240 Vac)

AC cord length

6 feet

Current at 120 volts

.25 amps

Current at 240 volts

.125 amps

Frequency

50 Hz to 60 Hz

Power consumption

9 watts

Output voltage

5.1 Vdc

DC cord length

8 feet

Output current

1.8 A

DECrepeater 90C Input
Specification

Value

Input voltage

4.75 Vdc to 5.25 Vdc

Input current

1.0 amp

Parts List
Replacement Part

Part Number

DECrepeater 90C

DECMR-MA

Power supply, 110 Vac

H7082-AA

Power supply, 220 Vac

H7082-BA

B
Related Documentation
You can order the following documents from Digital:
Document Title

Order Number

DECbridge 90 Owner’s Manual

EK–DEWGB–OM

DEChub 90 Owner’s Manual

EK–DEHUB–OM

Open DECconnect Building Wiring
Components and Application Catalog

EB–K2407–42

DECrepeater 90T Owner’s Manual

EK–DETMR–OM

DECconnect System Planning and
Configuration Guide

EK–DECSY–CG

B–1

C
Management Details
Chapter 4 provides information on managing the DECrepeater 90C on a
network or in a standalone configuration. This appendix provides more
information on managing a DECrepeater 90C in a DEChub 90 backplane:
•

Designating a hub manager

•

Annotating the bridge address table

•

Using the WGB address table for work group management

Designating a Hub Manager
The protocol used on the DEChub management bus allows only one
manager unit to access the management bus. When a DECbridge 90 is
first powered on or reset, it waits 60 seconds before designating itself as
the designated hub manager. This delay ensures that there is no other
manager unit in use in the hub.
During this 60-second period, you cannot manage the DECrepeater
90 units remotely. This restriction does not apply to the repeaters
themselves. A repeater inserted into the hub is immediately manageable
by whatever unit is currently the designated hub manager.
If you receive the message The DECbridge 90 is not the designated hub
manager. after the DECbridge 90 has been running for more than 60
seconds, there is something wrong.
•

If you are using two DEChub 90 units, make sure the MMJ cable is
wired correctly, and it not shorted or broken.

•

If you are using only one hub, the MMJ connector should be
disconnected.

•

Only one DECbridge 90 unit is allowed in the hub. If more than one
DECbridge 90 unit is installed, only one of them can manage the
repeaters. The other unit issues the message indicating it is not the
manager.
C–1

C–2 Management Details

If for some reason you do not want a specific DECbridge 90 unit to be the
designated hub manager, you can disable the hub management features
with the command DEFINE BRIDGE HUB_MANAGEMENT DISABLE.
After the DECbridge 90 has become the designated hub manager, you
can use SET or SHOW REPEATER and SET or SHOW PORT commands
without restriction. There is, however, an additional delay before the
SHOW ADDRESS command provides complete information.
DEFINE commands do not take effect until the next SET ALL or RESET
of the DECbridge 90. To have the command take effect immediately, you
must also issue the corresponding SET command.

Annotating the Bridge Address Table
The DECbridge 90 SHOW ADDRESS command lists the DECrepeater
slot number and port number for every station in the work group
that is connected to the same DEChub by a DECrepeater. However,
when changes are made to the network topology, it takes time for that
information to appear in the DECbridge 90 address table. The algorithm
for creating this information proceeds as follows:
For every station in the work group
•

Tell the repeaters to wait for a message from this station.

•

Wait up to 90 seconds for the station to transmit a message.

•

Ask the repeaters what port it came from.

If a station does not transmit a message within 90 seconds, the
algorithm proceeds to the next station. In a typical network situation,
this process is completed in a few minutes. After a bridge is newly
installed or reset, you can expect this information to be complete after
about 10 minutes of operation.
If some stations do not often transmit messages, the DECbridge may
hang on those stations for up to 90 seconds each before moving on. If you
add a station, or move it to another port, you can expect it to take about
10 minutes before a SHOW ADDRESS command recognizes this move.
If you remove a station from the network entirely, it will take a full
address age time (default is 30 minutes) for the DECbridge 90 to notice.
If you remove many stations at once, the DECbridge 90 hangs on each
of these stations for 90 seconds, until they age out of the bridge address
database. In this case, it will usually take the full address age time (30
minutes) before the port number annotations are complete.

Management Details C–3

As a worst-case example, if it takes 60 seconds for each of the allowed 200
stations to transmit a message, it could take 200 minutes to complete the
address database annotations. However, the DECbridge 90 tries to hurry
things along.
•

If the station remains quiet after waiting 30 seconds for a message,
the DECbridge 90 tries to generate a response by using the IEEE XID
request.

•

If the IEEE XID request fails, the DECbridge 90 tries a MOP SystemID request.

For these reasons, the DECbridge 90 never hangs for more than 30
seconds on an IEEE-conforming station, nor more than 60 seconds on
any Digital station that predates the IEEE specifications. If you are
monitoring messages and protocols on your work group Ethernet, you
occasionally see these messages.

Using the WGB Address Table for Work Group Management
The work group bridge (WGB) Ethernet address table is dynamic.
Ethernet addresses are added to the table when a device first transmits on
the network. Addresses are removed when a devices does not retransmit
within a user-specified period, from 1 to 32767 seconds (about 10 hours).
The default setting is 15 minutes. When a device is learned or relearned
after it has timed out, its address is listed in the lowest empty entry of
the address table.
This continuous learning, timeout, and relearning of the Ethernet
addresses means that devices in a particular work group may or may
not be in the address table at any moment. If they are in the address
table, they may not be in a consistent database location. Devices such as
personal computers and laptops that are often removed and reconnected
will certainly time out from the address table. When reconnected, the
addresses for these devices are be stored in a different address table
location.
Because the address table is dynamic, the network manager cannot easily
compare printouts of the WGB address table to determine work group
changes on a day-to-day or week-to-week basis.

Index
A
Address number, 4–6

B
Backplane
connector, 1–4
DEChub 90, 1–1
10Base2, 1–1
BNC network connector, 1–4
Bridge names
maximum length, 4–3

C
Cables
connections, 3–4
Commands
abbreviations, 4–5
arguments and parameters, 4–5
console carrier, 4–5
descriptions, 4–6
Configurations
installation, 3–1
Connection
sample, 1–1
Connector
backplane, 1–4
power, 1–4
Connectors
network (BNC), 1–4
port (BNC), 1–4
Console carrier

Console carrier (Cont.)
commands, 4–5
establishing a session from
ULTRIX, 4–3 to 4–4
establishing a session from VMS,
4–2 to 4–3
user interface, 4–4
Cover, 1–4
CSMA/CD, 1–1

D
DC OK indicator, 1–4, 4–19
DEChub 90, 1–1
DECrepeater
input current, A–3
input voltage, A–3
Depth, A–1
Dew point, A–2
Dimensions
physical, A–1

E
Environment
operating, A–2
Environmental
specifications, A–2
Error messages, 4–16
Ethernet addresses, 4–2, 4–4
in NCP database, 4–3
Ethernet circuit names, 4–2, 4–4

Index 1

2 Index

Features, 1–1

Network activity indicator, 1–4,
4–19
Network connector (BNC), 1–4
Network control program (NCP),
4–2
Networks
CSMA/CD, 1–1
IEEE 802.3, 1–1

H
Height, A–1
Help command, 4–5
Hub number, 4–6
Humidity, A–2

I
IEEE 802.3, 1–1
Installation
backplane, 3–6 to 3–8
configurations, 3–1
standalone, 3–1 to 3–5
wall-mounted, 3–1 to 3–5

L
LED indicators
DC OK, 1–4, 4–19
network activity, 1–4, 4–19
port status, 1–4, 4–19

M
Maintenance operations protocol
(MOP)
access from ULTRIX, 4–3
access from VMS, 4–2
commands, 4–5
functions, 4–1
Management, 4–1
Management protocol
partitioned, 4–11

O
Operating
altitude, A–2
dew point, A–2
environment, A–2
relative humidity, A–2
temperature, A–2
temperature change, A–2

P
Partitioned, 4–11
Password
length, 4–7
Physical dimensions, A–1
Port connector (BNC), 1–4
Port number, 4–6
Port status indicators, 1–4, 4–19
Power
120 Vac, 1–1
240 Vac, 1–1
Power connector, 1–4
Power supply, 1–1
current, A–3
frequency, A–3
output current, A–3
output voltage, A–3
power consumption, A–3
specifications, A–3
voltage, A–3

Index 3

Relative humidity, A–2
Repeater
managed, 1–1
unmanaged, 1–1
Repeaters
disabling ports, 4–7
port numbers, 4–9
show repeater command, 4–9
slot numbers, 4–9

Temperature, A–2
maximum rate of change, A–2
Troubleshooting, 5–8
DECrepeater 90C in DEChub 90
backplane, 5–6 to 5–8
error messages, 4–16
standalone DECrepeater 90C,
5–2 to 5–4

U
S
Sample connection, 1–1
Shipping
altitude, A–2
environment, A–2
relative humidity, A–2
temperature, A–2
Specifications
environmental, A–2
power supply, A–3
Standalone unit
installation, 3–1 to 3–5
Status indicators, 1–4, 4–19

ULTRIX
Maintenance operations protocol
(MOP) option, 4–3

V
VMS
Maintenance operations protocol
(MOP), 4–2

W
Weight, A–1
Width, A–1