Allied Telesis CentreCOM AT-3675 Bridge User manual

Allied
Telesyn
CentreCOM 
AT-3675 Bridge
SNMP Manageable
User Manual

 Copyright 1994 Allied Telesyn International, Corp.
All rights reserved. No part of this publication may be reproduced without prior written permission from
Allied Telesyn International, Corp.
Allied Telesyn International, Corp. reserves the right to make changes in specifications and other
information contained in this document without prior written notice. The information provided herein is
subject to change without notice. In no event shall Allied Telesyn International, Corp. be liable for any
incidental, special, indirect, or consequential damages whatsoever, including but not limited to lost profits,
arising out of or related to this manual or the information contained herein, even if Allied Telesyn
International, Corp. has been advised of, known, or should have known, the possibility of such damages.
Trademarks: CentreCOM is a registered trademark of Allied Telesyn International, Corp. Ethernet is a
registered trademark of Xerox Corporation. UNIX is a registered trademark of UNIX System
Laboratories. Novell and NetWare are registered trademarks of Novell, Inc. Microsoft and MS-DOS are
registered trademarks and LAN Manager and Windows for Workgroups are trademarks of Microsoft
Corporation. 3Com is a registered trademark of 3Com. PC-NFS is a trademark of Sun Microsystems, Inc.
PC/TCP is a registered trademark of FTP Software, Inc. DECnet is a registered trademark of Digital
Equipment Corporation.

xi
Table Of Contents
Electrical Safety and Installation Requirements .....................................................i
Table Of Contents ..........................................................................................................xi
Chapter 1
Overview ........................................................................................................................... 1
CentreCOM AT-3675 SNMP-Manageable Bridge...................................................................................... 1
Performance ............................................................................................................................................... 1
Management............................................................................................................................................... 2
Physical Description........................................................................................................................................ 2
Features Summary.......................................................................................................................................... 3
Chapter 2
Installation ....................................................................................................................... 5
Site Selection..................................................................................................................................................... 5
Factory Configuration..................................................................................................................................... 5
Changing Configuration with Transceivers................................................................................................. 6
Switching Configuration with Jumpers........................................................................................................ 6
Upgrading Bridge Firmware......................................................................................................................... 8
Chapter 3
Operation .......................................................................................................................... 9
Power On........................................................................................................................................................... 9
Diagnostics........................................................................................................................................................ 9
Normal Operation............................................................................................................................................. 9
Backup Operation........................................................................................................................................... 10
Application Guidelines................................................................................................................................... 10
Fault Tolerance and Isolation....................................................................................................................... 14
Chapter 4
Troubleshooting ............................................................................................................ 17
Product Code and Serial Number................................................................................................................ 17
Appendix A
Data Cabling Techniques ............................................................................................ 19

xii
10BASE-T....................................................................................................................................................... 19
UTP Wiring
Specifications.................................................................................................................................. 19
10BASE-T Point-to-Point Cabling....................................................................................................... 20
10BASE-FL/FOIRL Ethernet ................................................................................................................... 23
10BASE2 (Thin) Ethernet........................................................................................................................... 23
10BASE5 (Thick) Ethernet ......................................................................................................................... 23
AUI Drop Cables.................................................................................................................................... 24
Appendix B
Glossary ............................................................................................................................25
Appendix C
Technical Support Fax Order .....................................................................................31
Incident Summary......................................................................................................................................... 31
Appendix D
CentreCOM AT-3675 Manual Feedback ....................................................................33
Index .................................................................................................................................35

1
Chapter 1
Overview
CentreCOM AT-3675 SNMP-Manageable Bridge
The CentreCOM AT-3675 SNMP-Manageable Learning Bridge allows you
tointerconnect two Ethernet sub-networks.Eachsub-networkmaybeIEEE
802.3 10BASE2 (thin) Ethernet or 10BASE5 (thick) Ethernet or pre-802.3
Ethernet. Unshielded Twisted Pair (UTP) can also be connected to the bridge
through a transceiver. The AT-3675 bridge transparently forwards packets.
Since the bridge operates at the Media ACcess (MAC) level, all higher level
protocols, such as Transmission Control Protocol (TCP), DECnet™ and
NetWare®, are passed unaffected.
Performance The four repeater rule does not apply across the bridge. The effective length
of a Local Area Network (LAN) can be increased by adding a CentreCOM
AT-3675 SNMP-Manageable Learning Bridge. Placing bridges at natural
boundaries of the workgroups increases the network performance at each
segment by diminishing network traffic. The reliability of a large network can
be enhanced by a bridge and allows sub-networks of different media types to
be interconnected.
The CentreCOM AT-3675 is self-learning, adjusting to reconfiguration of sub-
nets to provide continuous isolation of local traffic. The AT-3675 provides
packet filtering at 25,000 Packets Per Second (PPS) and sustained forwarding
at 12,500 PPS. Its filter table supports 2,048 MAC-level station addresses.
Multiple AT-3675 bridges can be used as backups in case of network failure.
The AT-3675 supports the IEEE 802.1 Spanning Tree Protocol (STP), which
provides redundancy link management and network loop checking. STP
allows backup bridges to provide fault tolerant networks by placing the
bridges that form loops into a standby state until an active bridge fails. When
failure occurs, the network is reconfigured and any loops are eliminated. This
network reconfiguration occurs without impacting the network users or the
applications.

Overview
2
Management Simple Network Management Protocol (SNMP) is supported by the AT-3675.
The bridge can be monitored and manipulated by many SNMP-compatible
management stations. Since it supports the second version of the
Management Information Base (MIB-II) and Bridge MIB, parameters of the
AT-3675 can be managed under SNMP including custom filtering, static
forwarding entries and STP.
Physical Description
The AT-3675 bridge is housed in the slim-line chassis. All network
attachments, the power connector and status indicators are located on the
front panel. See Figure 1.
Media selection for the bridge’s A and B channels are controlled by jumper
blocks on the main board inside the chassis.
There are three pairs of indicators on the AT-3675 front panel. Two pairs
indicate network activity forChannels A and B. The third pair of indicators is
System Power and Diagnostics. The names of the indicators and their
functions are described in Table 1.
Table 1: AT-3675 Front Panel Indicators
The two 10BASE2 network connectors are standard Bayonet Nut Couples
(BNCs). The two 10BASE5 network connectors are standard Attachment
Unit Interfaces (AUIs) and accept standard 10BASE2, fiber optic
(10BASE-FL, FOIRL), 10BASE-T transceivers and 10BASE5 drop cables.
Since the AT-3675 bridge has the same dimensions as the AT-3600 Series
Repeaters, it may be mounted in an ATI rackmount or desktop chassis.
Indicator Function
Transmit A Channel A Transmitting
Receive A Channel A Receiving
Transmit B Channel B Transmitting
Receive B Channel B Receiving
Diagnostics Diagnostic Test Status
System Power Power is ON
Figure 1: AT-3675 Front Panel
POWERSYSTEM ACTIVITY
Illumination indicates
line voltage available.
Indicator continually illuminated
during self test, then off.
Indicator will flash if error detected.
CHANNEL BCHANNEL B
TRANSMIT
RECEIVE
TRANSMIT
RECEIVE
10BASE2 10BASE5 DIAGNOSTICS
3675 CentreCOMTM
IEEE 802.3/ETHERNETBRIDGE
with SNMPManagement
CHANNEL A
10BASE2 10BASE5
CHANNEL A
SYSTEM POWER

CentreCOMAT-3675 SNMP-Manageable Learning Bridge
3
Not all chassis slots must be populated and populated slots need not be
contiguous. Table 2 lists chassis models available.
Table 2: Department Concentrators Chassis Available
Features Summary
❑Self -learning SNMP-Manageable Learning Bridge
❑Filter at 25,000 PPS
❑Forward at 12,500 PPS
❑Thinnet (for 10BASE2) and thicknet (for 10BASE5 or pre-802.3
Ethernet) media options on each network segment
❑Fiber optic (10BASE-FL, FOIRL) or UTP with the addition of an
optional transceiver(s)
❑Supports 2,048 MAC addresses in filter table
❑IEEE 802.1 revision D STP
❑Standalone, desktop, or rackmount, chassis installation
❑SNMP management
❑MIB-II and Bridge MIB (RFC 1493)
❑One year free software upgrades
❑One year warranty
Number of Modules Desktop Model Rackmount Model
1 AT-36E1 AT-36C1
2 AT-36E2 AT-36C2
3 AT-36E3 AT-36C3
4 AT-36E4 AT-36C4
8 AT-36E8 AT-36C8

5
Chapter 2
Installation
Before installing the CentreCOM AT-3675 SNMP-Manageable Learning
Bridge, check to see that the package contents are complete. If any of the
following items are missing or damaged, contact your sales
representative.
❑CentreCOM AT-3675 SNMP-Manageable Learning Bridge
❑User Manual
❑Warranty statement and registration cards
❑Power cord (U.S.A. version only)
Save the shipping carton and packing material in case you need to ship or
store the bridge in the future.
Site Selection
Before installing the AT-3675 bridge, read the safety installation
requirements starting on page i.
The AT-3675 bridge should be placed in a cool, well-ventilated area. Air vents
are located on each side of the bridge. It is very important that none of the
vents is obstructed. Several inches of clearance should be allowed between
these vents and any other object, e.g., a wall or other equipment.
Failure to follow these ventilation guidelines may result in overheating and
eventual damage of the bridge.
Factory Configuration
The AT-3675 bridge is configured at the factory to use the AUI ports on both
channels. The AUI connectors (labeled 10BASE5) are active. If you use the
bridge in anIEEE 802.3 10BASE5 (or a pre-802.3Ethernet) environment, no
additional configuration is required.
!
Attention
!
Caution

Installation
6
Changing Configuration with Transceivers
You can attach cable of different media to one or both channels via a
transceiver. Table 3 list the transceivers avaiable.
Table 3: ATI Micro Transceiver Choices
Switching Configuration with Jumpers
Each channel can be switched between the BNC connector (labeled
10BASE2) and the AUI connector (labeled 10BASE5). To switch connectors,
you move a jumper block inside the bridge chassis.
Channels A and B are set at the factory to operate with pre-802.3Ethernet or
IEEE 802.3 10BASE5.
To determine which port is connected
If you are not sure which port is active for a given channel, you can check as
follows:
1. Connect one of the channel’s two ports to a cable that is transferring data.
2. If the channel’s Receive indicator flashes, you have selected the active
port, if not, the other port is active.
To change the jumper block
If you need to switch port connections for Channel A and/or Channel B, find
the locations of the jumper blocks as shown in Figure 2. Look up the proper
jumper block position(s) as listed in Table 4.
1. Remove the power cord and any cables from the AT-3675 front panel.
Openingthebridge without unplugging the powercordmayexposepersonnel
to high voltage, risking the possibility of injury or death. See safety
statements starting on page i.
2. Remove the three screws along the front edge of the top.
3. Turn the bridge upside-down and loosen the top cover by removing the
three screws along each side and the three screws along the back.
4. Remove the top cover by sliding it towards the back. If the cover fits
tightly, use a screwdriver to dislodge it.
Model Description
AT-MX25F Fiber Optic (FOIRL, 10BASE-FL), SMA Connector
AT-MX26F Fiber Optic (FOIRL, 10BASE-FL), ST Connector
AT-210T/AT-210TS/AT-MX20T UTP (10BASE-T)
AT-MX10/AT-MX10S Thin Ethernet (10BASE2)
Note
Warning