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DEC-08-XPDBC-B-D

May 1977

6 pages

Original

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Document:	06.01.01 7705 DECNET8
Order Number:	DEC-08-XPDBC-B-D
Revision:
Pages:	6
Original Filename:	http://bitsavers.org/pdf/dec/spd/06.01.01_7705_DECNET8.pdf

OCR Text

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Software Product Description
PRODUCT NAME:

DEeNET /8, Version 1, RTS/S Network Software

SPD 6.1.1

All references to DECNET /8 in this Software Product Description are to DECNET /8, Version 1.

SECTION A: DECNET IS SPECIFIC INFORMATION
DESCRIPTION:
DECNET /8 extends the capabilities of the RTS/8
operating system by enabling RTS/8 to be interconnected with other DECNET /8 Systems running in a
DECNET /8 environment. DECNET /8 can be used as
a component of distributed networks, resource sharing networks and communications networks. The
DECNET /8 implementation of Digital Network Architecture (DNA) allows the following functions to be
performed:
• Tasks running in the RTS/8 environment can exchange data with other tasks executing under
DECNET /8 on the same or other processors in the
network.
• Tasks written in PAL8 can request the execution of
programs in other systems in the network and can
cause programs executing in remote systems to be
terminated.
• The local operator can request that a description
of current network status, including connected
nodes and their state, be printed at a local terminal.
• The local operator can exchange messages with
operators at remote terminals in the network.
In order to support these functions, DECNET /8 conforms to the current protocols which collectively define Digital Network Architecture (DNA). The features
of the DNA which are implemented in DECNET /8
include:
• Support of the Digital Data Communications Message Protocol (DDCMP) for full and half duplex
transmissions in point-to-point mode only, using
synchronous, asynchronous and parallel facilities.
DDCMP provides error detection / correction and
line management facilities.
• Support of the Network Services Protocol (NSP)
for point-to-point network connections. NSP allows
tasks on DECNET systems to establish logical
communications channels between themselves on
a dynamic basis, and to transfer variable-sized
messages on a requested or non-requested, that is
interrupt, basis using these logical channels. Requested messages are limited to 192 bytes maximum; interrupt messages are limited to 16 bytes in
length maximum. NSP multiplexes data through
physical links on a message basis, thus allowing
many logical channels to share a single physical
link.

May 1977

NOTE: Some changes to these protocols may occur
and future releases of DECNET /8 may not be fully
compatible with DECNET /8, Version 1.
DECNET /8 is implemented as a series of tasks and
subroutines operating under RTS/8 in conjunction
with communications device drivers included in the
RTS/8 system. Permanent memory residency requirements are approximately 5K words for network
code, plus 1 K words for each line (including buffer
and Interrupt Service Routine) to effectively handle
the maximum NSP data message, plus an additional
minimum 4K words required for the RTS/8 operating
system. The utility routines which support many
DECNET functions, together with low priority user
tasks, can be stored on the system device and
swapped into user-program partitions to be executed as required.

THROUGHPUT:
The throughput of DECNET /8 is a function of many
variables, especially the communications interfaces
used and the other activities executing concurrently
in the RTS/8 environment.
The table below describes the maximum throughput
of DECNET /8 when used with various communications devices. The columns have the following
meanings:
Number of lines: The largest practical number of
lines that can be driven by the DECNET /8 system,
independent of the various throughput considerations given at maximum speed.
Maximum line speed: The fastest clock rate at which
the device can be driven under DECNET /8.
Steady state throughput per line: The actual data
rate, as measured by the user program, for a line
running at the maximum line speed indicated above.
This measured value obtained under double buffering with Software CRC Computation.
Aggregate line speed: The total permissible
bandwidth of all communications devices of this type
on the DECNET System. Aggregate line speed
should be calculated for all lines known to operate
concurrently.

DEC-OS-XPDBC-B-D

DECNET /8, Version 1

SPD 6.1.1
-2-

Maximum aggregate throughput: The total data
throughput, as measured by the user programs, of
all lines on the OECNET /8 System, assuming each
is to be operated at its maximum line speed, obtained under same conditions as Steady State
Throughput.
Mode: This reflects the use of the line in either a
half-duplex (i.e. one bit stream) or full-duplex (i.e.
two concurrent bit streams) mode. The FOX Steady
State figures indicate data throughput in one direction only.

Each row of the table indicates the maximum loading of the OECNET /8 system with communications
related tasks operating at the highest software priorities.
NOTE:
Data Format: All network data manipulated by
ODCMP and NSP consists of 8 bit bytes stored one
per 12 bit PDP-8 Word.

DEeNET /8 PERFORMANCE

No.
of Lines

Max. Line
Speed
FXD

Steady State Aggregate
Throughput Line Speed
Per Line
One Direction

Maximum
Aggregate
Throughput

Mode

%CPU
Usage
(For Max.
Aggregate)

9.6

5.9
5.9

24
22

FOX
HOX

95%
90%

Multi Line ASYNCH
(KL8-A)

9.6

5.9
5.9

38.4
38.4

24
22

FOX
HOX

95%
90%

Single Line SYNCH
(OP8-E)

9.6

5.9
5.9

38.4
38.4

24
22

FOX
HOX

95%
90%

30':'

20.0

FOX

85%

Processor: 8A, 8E
Single line ASYNCH
(KL8-JA, KL8-M)

38.4
38.4

.----------------~~-~---

Parallel
(OKC8-AA)

---~-----------------------------~---------

':' Approximate.
NOTE: These figures were obtained with Software CRC Double Buffering and Maximum Message length. Throughput performance can be enhanced by approximately 20% using KG8-E hardware. Rates are given in K-bits per second.

DECNET/S, Version 1

SPD 6.1.1
-3-

MINIMUM HARDWARE REQUIRED:
Any valid RTS/S System configuration with:
• SK words additional memory
• one or more of the following communications
devices:
KL8-JA Asynchronous Serial Line Interface
DKC8-AA 1/0 Option Board (Serial or Parallel
Support)
KLS-A Four Channel Asynchronous Serial Line
Interface
KLS-JA with KLS-M Modem Control
DPS-E Synchronous Serial Line Interface

UPDATE POLICY:
Software Updates, if any, released by DIGITAL during the one (1) year period following installation, will
be provided to the customer for a media charge. After the first year, updates, if any, will be made available according to then prevailing DIGITAL policies.

OPTIONAL HARDWARE SUPPORTED:
Additional communications devices from above (except DKCS-AA) up to a recommended maximum of 4
KL8-JA's or 2 KL8-A's or 4 DP8-E's
KG8-E Communications Arithmetic Element
Note: KGS-E is strongly recommended where Line
Throughput is an important consideration.

Source andlor listing options are only available after
a source license agreement is in effect.

PREREQUISITE SOFTWARE:
RTS/S Operating System Version 2B or later
OPTIONAL SOFTWARE SUPPORTED:
None
TRAINING CREDITS:
None
SUPPORT CATEGORY:
B - Software Support will be provided as listed in
the Software Support Categories Addendum to this
SPD.
PREREQUISITE SUPPORT:
The customer is required to purchase installation
services at each facility where DECNET IS will be
used. If additional DECNET 18 systems are present at
the same facility, additional installation services may
be purchased at the customer's option. The customer can purchase DECNET 18 licenses with NO
services if an OEM Agreement or End-User Waiver
of Support Agreement is in effect. The inclusion of
any DECNET I S software with a Category C classification causes the support classification for all DECNET software in the network to revert to Category C.

ORDERING INFORMATION:
This software is furnished under a license for use on
a single CPU and can be copied and modified (with
inclusion of DIGITAL's copyright notice) only for use
on such CPU, except as may otherwise be provided
in writing by DIGITAL.

The following key ( C, R, Y) represents the distribution media for the product and must be specified at
the end of the "Q" number, i.e., QF6S0-XY =
sources on floppy disk.
C
DECtape
R = Microfiche
Y = Floppy Disk
Standard Options

QF680

-X- Single-use license, source license,
sources, support services (media: C,

Y)
Sourcel Listing Options

QF680

-F-

Listings (media: R)

ADDITIONAL SERVICES:
None
06.1.1

DECNET-8, Version 1

SPD 6.1.1
-4-

SECTION B: OECNET GENERAL DESCRIPTION
DECNET is the collective name for the set of software products that extend various DIGITAL operating systems by enabling the user to interconnect
these systems with each other to form computer networks. The DECNET user can configure a variety of
networks, satisfying a variety of constraints, by
choosing the appropriate CPU's, line interfaces (and
speeds) and operating system software.
In order to satisfy these widely varying constraints,
DECNET allows the user to build networks from a
range of systems and communications components.
DECNET allows users to interconnect systems using
serial asynchronous, serial synchronous, and parallel
facilities. 1 When configuring DECNET systems, it is
important to remember that both ends of any given
link must use the same type of communications discipline (e.g., synchronous, asynchronous or parallel)
running at the same line speed.
DIGITAL Network Architecture
DECNET includes a set of network protocols, each
of 'which is designed to fulfill specific functions
within the network. Collectively, these protocols are
known as the DIGITAL Network Architecture, or
DNA. The major protocols, and their functions, are:
DIGITAL Data Communications Message Protocol
(DDCMP): DDCMP handles the link traffic control
and error recovery within DECNET. DDCMP operates over full and half duplex facilities, using synchronous, asynchronous and parallel facilities in a
2
point-to-point and multidrop (polled) mode. DDCMP
has the following important characteristics:
• Operates over a wide variety of hardware types.
• Fully uses full duplex channel capacity.
• Allows transmission of all data types (including
binary) with low overhead.
• Operates with conventional (e.g., character-oriented) communications hardware.
• Uses CRC-16 for error detection, with correction
by retransmission.
• Effective on earthlsatellite links (or other links)
with long signal propagation delays.

A full specification for DDCMP is available on
request. DIGITAL does not regard DDCMP as a
proprietary protocol, and allows others to implement
and use the protocol, providing they acknowledge
its use in their public documentation.
Not all DECNET systems support all three modes of interconnection.
2 Not all DECNET systems support all DDCMP modes of
operation.
1

Network Services Protocol (NSP). NSP handles network management functions within DECNET, including the routing of messages between systems, and
the routing of messages within any given system.
NSP makes it possible for two programs on different
machines to establish a logical communications
channel (or link) between themselves, and to exchange data using this link. These programs need
not be aware of either the nature of the link
(fuil/half duplex; parallel or serial) or the nature of
the protocols supporting the link. NSP has the following important characterstics: 3
• Dynamic creation of logical links between tasks.
• Exchange of data between tasks on a solicited
basis.
• Exchange of data between tasks on a non-solicited
(e.g., interrupt) basis.
• Route-through of message traffic within the network (e.g., two nodes can communicate through
intermediate nodes which reroute messages to
their ultimate destination).
• Dynamic management of network topology (e.g.,
each node in the network is kept informed on the
current state of various other nodes and links in
the network).

A full specification for the Network Services Protocol
is available on request. NSP is not a proprietary protocol.
Data Access Protocol (DAP): The Data Access Protocol enables programs on one node of the network
to use the 110 services available on other network
nodes. Each operating system in DECNET provides
facilities for translating its. own unique 1/0 calls into
the DAP standard, and vice versa. Thus, DAP enables data requests to be processed in a meaningful
way by many (possibly heterogenous) operating systems. DAP's facilities include: 4
• Remote file access, including OPEN, READ,
WRITE, CLOSE and DELETE for sequential and
random access files.
• Remote device access for unit record devices.
• Virtual terminal support (e.g., allowing an interactive terminal physically connected to one system in
the network to operate (logically) as if it were connected to another system in the network).
3Not all DECNET systems support all NSP features.
4Not all DECNET systems support DAP.

SPD 6.1.1

DECNET -8, Version 1

-5It should be noted that each DAP function requires
support at both ends of the network. At the local
node, where the user program initiates a data
request, the DAP support must package the request
for transmission through the network. At the remote
node (where the device or file resides), the DAP
support must cause the appropriate actions to be
performed. Not all systems support both local and
remote portions of each DAP operation.
A full specification for the Data Access Protocol is
available on request. DAP is not a proprietary protocol.
DECNET Functions
Digital Network Architecture, implemented across a
wide range of operating systems and hardware configurations, enables users to build a variety of networks. Such networks have some common attributes, and individual systems in the network may
have certain system-specific attributes. The common
attributes include:
• Inter-program communication: Programs on one
system can create logical channels and exchange
data with programs on other systems in a real-time
fashion.
• Inter-system resource sharing: Programs on one
system can use files and devices physically attached to other systems in the network.
Additionally, many DECNET systems support other
features which are useful in network environment.
These include:
• Down-line System Loading: Initial memory images
for other systems in the network can be stored on
the local system, and loaded on request into other
systems in the network. The remote systems usually require the use of a network bootstrap loader,
implemented in read-only memory.
• Down-line Program Loading: Programs to be executed on other systems in the network can be
stored on the local system, and loaded on request
into other systems, under the joint control of the
operating systems at both ends of the network.
This and the preceding feature simplify the operation of network systems which do not have mass
storage devices, by allowing such systems to use
remote mass storage devices in a convenient and
straightforward manner.
• Inter-system File Transfer: This facility allows an
entire data file to be moved between systems, at
either program or operator request.

Cross-system Support: This facility allows program
development activities to be performed on a system different than the one where the programs will
be executed.
• High-level Language Interface: This facility allows
programs written in compiler languages (e.g., FORTRAN, COBOL, BASIC) to access some or all of
the network facilities.
Configuring DECNET Networks:
DECNET provides, as far as possible, a general interconnection mechanism between specific products, limited only by the technology and cost considerations which constrain each individual member of
DECNET. These latter constraints make totally general interconnectability impractical. The reader
should consult the individual product SPD's to
determine whether any particular configuration
violates the throughput guidelines for the individual
product.
TRAINING CREDITS:
No training credits are included in DECNET Software License charges. Training courses on DECNET
software are scheduled at regular intervals in DIGITAL Training Centers. Arrangements should be
made directly with DIGITAL's Educational Services
Department.
SUPPORT CATEGORY:
The support categories for the various DEGNET software products are described in the individual SPD's.
UPDATE POLICY:
The update policies for the various DECNET products are described in the individual SPD's.
ORDERING INFORMATION:
This software is furnished under a license for use on
a single CPU and can be copied and modified (with
inclusion of DIGITAL's copyright notice) only for use
on such CPU, except as may otherwise be provided
in writing by DIGITAL.
When multiple systems are connected in a single
network, then each individual system must be licensed separately with regard to both operating system and DECNET software.
ADDITIONAL SERVICES: .
The following additional services are offered to enable users to gain the maximum benefit from their
DECNET software.

OECNET-8, Version 1

SPO 6.1.1
-6-

Installation Service: The installation shall consist of:
• Verifying that the software kit contains all software
modules and manuals offered.
• Generating the DEGNET software.
• Demonstrating the use of the majority of operator
commands and system utilities.
• Running a sample DIGITAL-supplied program.
• Introducing the customer to the sources of DIG 1TAL software information and services.
• Prior to and during installation of the software, the
customer has the following responsibilites:
1. Obtain, install and demonstrate as operational
any modems, lines and other equipment and facilities necessary to interface to DIGITAL's communications interfaces and terminals.
2. Have previously installed all hardware, including
terminals, to be used on the system.
3. Make available to all DIGITAL personnel all
hardware, including communications facilities
and terminals, for a reasonable period of time
as mutually agreed upon by DIGITAL and the
customer, that is to be used during installation.
Additional services are described in the individual
SPD's as appropriate.