Digital Equipment DECrepeater 90C User manual

DECrepeater90COwner’sManual
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 vii
1 Overview
Features .............................................. 1–1
Installation . ........................................ 1–3
LEDs and Connectors . . . ................................ 1–4
2 Configuration
Configuration Rules ..................................... 2–1
Port Termination and Grounding . ........................ 2–1
Configuration Guidelines ............................... 2–1
Port Partitioning ....................................... 2–2
3 Installation
Standalone Installation . . ................................ 3–1
Select a location. ..................................... 3–1
Place the repeater on a table. . . . ........................ 3–1
Mount the repeater on a wall. . . . ........................ 3–2
Connect the cables. . . . ................................ 3–4
Install and verify devices. .............................. 3–4
Backplane Installation . . . ................................ 3–6
Remove the back cover. ................................ 3–6
Mount the repeater in the backplane. ..................... 3–7
Install and verify devices. .............................. 3–8
iii

iv Contents
4 Management
Managing the DECrepeater 90C . . . ........................ 4–1
Functions . . . ........................................ 4–1
Components Needed . . . ................................ 4–2
Accessing the MOP from VMS . . . ........................ 4–2
Accessing the MOP from ULTRIX ........................ 4–3
Console Carrier User Interface . . ........................ 4–4
Console Carrier Command Language........................ 4–5
Command Parameters . ................................ 4–6
Command Descriptions ................................ 4–6
Typical Management Techniques . . . ........................ 4–11
Remote Network Management With the DECbridge 90 . ....... 4–11
Management Disconnect ............................. 4–11
Management Session ................................ 4–13
If Problems Are Reported ............................. 4–14
Messages ............................................. 4–16
Standalone Configuration Management .................... 4–18
5 Troubleshooting
DECrepeater 90C Standalone Troubleshooting . ............... 5–2
DECrepeater 90C Backplane Configuration Troubleshooting ...... 5–6
A DECrepeater 90C Specifications
Physical Dimensions .................................... A–1
Environmental Specifications .............................. A–2
Operating Environment ................................ A–2
Shipping Environment Specifications ...................... A–2
Electrical Specifications . . ................................ A–3
Power Supply ........................................ A–3
DECrepeater 90C Input ................................ A–3
Parts List . . . ........................................ A–3

Contents v
B Related Documentation
C Management Details
Designating a Hub Manager .............................. C–1
Annotating the Bridge Address Table ....................... C–2
Using the WGB Address Table for Work Group Management . . . C–3
Index
Figures
1–1 Sample DECrepeater 90C Connection . . . ............... 1–2
4–1 Sample Configuration and Topology Map . ............... 4–12
4–2 Typical Network Topology Map ....................... 4–13
4–3 Typical Standalone Topology Map ..................... 4–18
Tables
1–1 DECrepeater 90C LEDs ............................. 1–4
2–1 DECrepeater 90C Partitioning ........................ 2–2
4–1 Summary of DECrepeater 90 Commands. ............... 4–5
4–2 DECbridge 90 Messages............................. 4–16
4–3 DECrepeater 90C Status LEDs ....................... 4–19
5–1 Troubleshooting a DECrepeater 90C Standalone Unit ...... 5–2
5–2 Troubleshooting a DECrepeater 90C in a DEChub 90
Backplane ....................................... 5–6

AboutThisManual
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 7-
port 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
Work Group ThinWire Segment
Ethernet Backbone
DECbridge 90
Work Group Bridge
PC Workstation DECserver
DECrepeater 90C
Workstation
DECrepeater 90T DECserver 90L
Computer 2Computer 1 Server
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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
! 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
6
4
5
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7
8
9
7
8
9
3
2
1

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.
Port0to6
Flashing — Partitioned by management.
Port1to6
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.
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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
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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.
PC
or
Workstation
50-Ohm
Terminator
T-Connector
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T-Connector
50-Ohm
Terminator

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.
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