3Com 5124M-TP, 5124M-TPCL User Manual

®

ONline Ethernet 24-Port

10BASE-T Module
Installation Guide

Document Number 17-00232-3

Printed February 1996

Model Number: 5124M-TPCL

5124M-TP

3Com Co rporation

118 Turnpike Road

Southborough, MA 01772-1886

U.S.A.

[phone]

FAX [phone]

Federal Communications Commission
Notice

This equipment has been tested and found to comply with the
limits for a Class A digital device, pursuant to Part 15 of the FCC
Rules. These limits are designed to provide reasonable protection
against harmful interference when the equipment is operated in a
commercial environment. This equipment generates, uses, and can
radiate radio frequency energy and, if not installed and used in
accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment
in a residential area is likely to cause harmful interference, in which
case you must correct the interference at your own expense.

Canadian Emissions Requirements

Cet appareil numérique respecte les limites de bruits
radioélectriques applicables aux appareils numériques de Classe A
prescrites dans la norme sur la matériel brouilleur: "Appareils
Numériques", NMB-003 édictée par le Ministère des
Communications.

This digital apparatus does not exceed the Class A limits for radio
noise emissions from digital apparatus as set out in the
interference-causing equipment standard entitled "Digital
Apparatus", ICES-003 of the Departm en t of Communications.

VDE Class B Compliance

Hiermit wird bescheinigt, dass der 5124M-TPCL in
Üebereinstimmung mit den Bestimmungen der Vfg 243/1991
funkentstöert ist.

Der Deutschen Bundespost wurde das Inverkehrbringen dieses
Geraetes angezeigt und die Berechtigung zur Üeberprüefung der
Serie auf Einhaltung der Bestimmungen eingeräeumt.

Einhaltung mit betreffenden Bestimmugen kommt darauf an, dass
geschirmte Ausfuehrungen gebraucht werden. Fuer die
Beschaffung richtiger Ausfuehrungen ist der Betreiber
verantwortlich.

This is to certify that the 5124M-TPCL is shiel ded against radio
interference in accordance with the provisions of Vfg 243/1991.

The German Postal Services have been advised that this equipment
is being placed on the market and that they have been given the
right to inspect the series for compliance with regulations.

Compliance with applicable regulations depends on the use of
shielded cables. The user is responsible for procuring the
appropriate cables.

EN55022/CISPR22 Compliance

This equipment conforms to the Class A emissions limits for a
digital device as defined by EN55022 (CISPR22).

VCCI Class 1 Compliance

This equipment is in the 1st Class category (information equipment
to be used in commercial or industrial areas) and conforms to the
standards set by the Voluntary Control Council for Interference by
Information Technology Equipment aimed at preventing radio
interference in commercial or industrial areas.

Consequently, when the equipment is used in a residential area or
in an adjacent area, radio interference may be caused to radio and
TV receivers, and so on.

Read the instructions for correc t handling .

UK General Approval Statement

The ONcore Switching Hub, ONline System Concentrator, and
ONsemble StackSystem Hub are manufactured to the International
Safety Standard EN 60950 and are approved in the UK under the
General Approval Number NS/G/12345/J/100003 for indirect
connection to the public telecomm unication network.

Disclaimer

The information in this document is subject to change without
notice and should not be construed as a commitment by 3Com
Corporation. 3Com Corporation assumes no responsibility for any
errors that may appear in this document.

Copyright State me nt

©

1996, by 3Com Corporation. Printed in U.S.A. All rights reserved.
3Com is a registered trademark of 3Com Corporation. ONcore is a
registered trademark of 3Com Corporation. The information
contained herein is the exclusive and confidential property of
3Com Corporation. No part of this manual may be disclosed or
reproduced in whole or in part without permission from 3Com
Corporation.

Trademarks

Because of the nature of this material, numerous hardware and
software products are mentioned by name. In most, if not all
cases, these product names are claimed as tradem arks by th e
companies that manufacture the products. It is not our intent to
claim these names or trademarks as our own.

Artel, Chipcom, Ethermodem, Galactica, ONcore, ORnet,
StarBridge, and TriChannel are registered trademarks of 3Com
Corporation.

Chipcom OpenHub, G-Man, LANsentry, MultiProbe, ONdemand,
ONline, ONsemble, PowerRing, SL2000, SL3000, SL4000,
StackJack, StackSystem, and SwitchCentral are trademarks of
3Com Corporation.

ii ONline Ethernet 24-Port 10BASE-T Module Installation and Operation Guide

The Chipcom Multichannel Architecture Communications System is
registered under U.S. Patent Number 5,301,303.

XNS is a trademark of Xerox Corporation.
DEC, DECnet, the Digital logo, DELNI, POLYCENTER, VAX, VT100,

and VT220 are trademarks of Digital Equipment Corporation.
IBM is a registered trademark of International Business Machines.

NetView is a trademark of International Business Machines.
3ComFacts, Ask 3Com, CardFacts, NetFacts, and CardBoard are

service marks of 3Com Corporation.
3Com, LANplex, BoundaryRouting, LanScanner, LinkBuilder,

NETBuilder, NETBuilderII, ParallelTasking, ViewBuilder, EtherDisk,
Etherl\Link, EtherLink Plus, EtherLink II, TokenLink, TokenLink Plus,
and TokenDisk are registered trademarks of 3Com Corporation.

3ComLaser Library, 3TECH, CacheCard, FDDILink, FMS, NetProbe,
SmartAgent, Star-Tek, and Transcend are trademarks of 3Com
Corporation.

CompuServe is a registered trademark of CompuServe, Inc.
3Com registered trademarks are registered in the United States,

and may or may not be registered in other countries. Other brand
and product names may be registered trademarks or trademarks of
their respective holders.

Restricted Rights

Use, duplication, or disclosure b y the G overnm ent 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.

Printed on recycle d paper.

ONline Ethernet 24-Port 10BASE-T Module Installation and Operation Guide iii

iv ONline Ethernet 24-Port 10BASE-T Module Installation and Operation Guide

How to Use This Guide

Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Structure of This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

Docume nt Convent ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Related Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi

3Com Doc uments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xvii

Reference Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xvii

Chapter 1 — Introduction

Ethernet 24-Port 10BASE-T Module Description . . . . . . . . . . . . . . . . . . . . . .1-1

Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2

Bank Switching Capabi lity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1- 3

Model Number 5124M-TPCL Features . . . . . . . . . . . . . . . . . . . . . . . . . .1-3

Model Number 5124M-TP Features . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4

Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4

Contents

Chapter 2 — Designing and Expanding the Network

Understand ing the Gener al Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

Rules for Configuring a Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

LAN Equivalence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6

Choosing a Network Backbone Cabling Structure . . . . . . . . . . . . . . . . . . . .2-7

Building a Network (Star Configuration) . . . . . . . . . . . . . . . . . . . . . . . .2-8

Building a Network (Serial Configuration) . . . . . . . . . . . . . . . . . . . . . . .2-9

24-Port Module Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-10

Fiber Backbone, 10BASE-T To-The-Desk . . . . . . . . . . . . . . . . . . . . . . . .2-10

10BAS E-T Backbone, 10BASE-T To-The-Desk . . . . . . . . . . . . . . . . . . . .2-12

Using Patch Panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14

Establishing Fault-Tolerant Configurations . . . . . . . . . . . . . . . . . . . . . . . . .2-14

Setting Port Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-15

Configuring Ports for Fault Tolerance . . . . . . . . . . . . . . . . . . . . . .2-15

ONline Ethernet 24-Port 10BASE-T Module Installation Guide v

Setting Backbone Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-15

Redun dant Twisted Pair Backbone . . . . . . . . . . . . . . . . . . . . . . . .2-16

Chapter 3 — Installing and Operating the Module

Precautionary Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

Quick Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

Unpacking Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4

Setting the DIP Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4

DIP Swi tch Over vi ew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5

DIP Swi tch Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7

Inst alling t he M odule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-10

Using 90° Cable Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-13

Inst alling the Cable Ti e-Wrap Kit . . . . . . . . . . . . . . . . . . . . . . . . . .3-1 3

Secur ing 90° Cables to the Mo dule . . . . . . . . . . . . . . . . . . . . . . .3-1 5

Configurat ion in a Managed Envir onment . . . . . . . . . . . . . . . . . . . . . . . .3-17

If Management is N ot Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-18

Before Configuring the Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-19

Enabling Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-19

Enabling Port Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-19

Enab ling Link I ntegrit y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-20

Selecting a Net work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-20

Enab ling Remot e Diagnos tics Mode . . . . . . . . . . . . . . . . . . . . . . . . . .3-21

Setting the Autopartition Threshold Value . . . . . . . . . . . . . . . . . . . . .3-22

Savi ng Module Co nfigurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-23

Showing Module Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-23

Show Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-24

Show Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-25

Gathering Network Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-27

Selecting the Per-Port Counters Connector . . . . . . . . . . . . . . . . . . . . .3-28

Monitoring the Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-29

Verifying LED and Network Assignments . . . . . . . . . . . . . . . . . . . . . . . . .3-32

Using the LED Check Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-32

vi ONline Ethernet 24-Port 10BASE-T Module Installation Guide

Chapter 4 — Troubleshooting

Troubleshooting Using the Port Status and Port Activity LEDs . . . . . . . . . . .4-2

Troubleshooting Using the Port Status LEDs . . . . . . . . . . . . . . . . . . . . .4-2

Troubleshooting Using the Port Activity LEDs . . . . . . . . . . . . . . . . . . . .4-4

Technical Assistan ce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4

Appendix A — Specifications

General Specificat ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2

Power Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

Environmental Specificat ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4

Mechanical Sp ecifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-5

Twisted Pair Cable and Co nnector S pecification s . . . . . . . . . . . . . . . . . . . . A-5

Twisted Pair Cable Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6

Twisted Pair Connect or Specif ications . . . . . . . . . . . . . . . . . . . . . . . . . A-7

RJ-45 C onnect or P inouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-7

50-P in Connector Pinou ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8

Connecting Twi sted Pai r Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Appendix B — Technical Support

On-line Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-1

Email Technical Suppor t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-2

World Wide Web Sit e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-2

Support from Your Network Supplier . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-2

Support from 3Com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-3

Returning Products for Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-4

Accessing the 3Com MIB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-4

3Com Tec hnical Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-5

Index

ONline Ethernet 24-Port 10BASE-T Module Installation Guide vii

vii i ONline Ethernet 24-Port 10BASE-T Module Installation Gu id e

Figures

Figure 1-1. Typi cal 24-Port Module C onfiguration . . . . . . . . . . . . . . . . .1- 5

Figure 2-1. Star-Wiring Configuration . . . . . . . . . . . . . . . . . . . . . . . . . .2-8

Figure 2-2. Serial Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9

Figure 2-3. Sample Configuration Distance Calculation Using

24-Port Mo dules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-11

Figure 2-4. Unshielded Twisted Pair Network U sing 24-Port Modu les .2-13
Figure 2-5. Redundant Twisted Pair Configuration Using 24-Port

Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-16

Figure 3-1. Model 5124M-TPCL and Model 5124M-TP DIP Switch

Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6

Figure 3-2. Installing a 24-Port Module (Model Number 5124M-TPCL) 3-11
Figure 3-3. 24-Port Module Cable Connection

Figure 3-4. Attaching the Tie-Wrap Bracket to the Module . . . . . . . . .3-14

Figure 3-5. Attaching Cables With 90° Con nectors

(Model Number 5124M-TPCL) . . . . . . . . . . . . . . . . . . . .3-15

Figure 3-6. Attaching Cables With 90° Connectors . . . . . . . . . . . . . . .3-16

Figure 3-7. 24-Port Module Faceplate and ONline System

Figure 3-8. 24-Port Module Faceplate and ONline System

Figure A-1. 24-P ort Module RJ-45 Con nector Pinouts . . . . . . . . . . . . . A-8

Figure A-2. 50-P in Male and Female Connectors . . . . . . . . . . . . . . . . . A-9

(Model Number 5124M-TPCL) . . . . . . . . . . . . . . . . . . . . .3-12

Concentrator (Model Number 5124M-TPCL) . . . . . . . . . . .3-29

Concentrator (Model Number 5124M-TP) . . . . . . . . . . . . .3-30

ONline Ethernet 24-Port 10BASE-T Module Installation Guide ix

x ONline Ethernet 24-Port 10BASE-T Module Installation Guide

Tables

Table 2-1. Seven Ba sic Network Rules . . . . . . . . . . . . . . . . . . . . . . . . .2-3

Table 2-2. LAN Product Equivalent Distanc es . . . . . . . . . . . . . . . . . . . .2-6

Table 3-1. Proc edures for Completing Inst allation . . . . . . . . . . . . . . . .3-2

Table 3-2. DIP Switch Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-8

Table 3-3. Channel (Network) Select DIP Switch Settings . . . . . . . . . . .3-9

Table 3-4. 24-Port Module LED Interpretations. . . . . . . . . . . . . . . . . .3-31

Table 3-5. Networ k Check Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . .3-33

Table 4-1. Troubleshooting Using the Port Status LEDs. . . . . . . . . . . . .4-2

Table 4-2. Troubleshooting Using the Port Activity LEDs. . . . . . . . . . . .4-4

Table A-1. 24-Port Module General Specifica tions. . . . . . . . . . . . . . . . A-2

Table A-2. 24-Port Module Powe r Specif i cations. . . . . . . . . . . . . . . . . A-3

Table A-3. 24-Port Module Fuse Specifications . . . . . . . . . . . . . . . . . . A-4

Table A-4. 24-Port Module Environmental Specifications. . . . . . . . . . . A-4

Table A-5. 24-Port Module Mechanical Specifications . . . . . . . . . . . . . A-5

Table A-6. IBM Twisted Pair Cable Specifications . . . . . . . . . . . . . . . . A-6

Table A-7. 50-Pin Cable Pinouts and Port Assignments . . . . . . . . . . . A-10

ONline Ethernet 24-Port 10BASE-T Module Installation Guide xi

This guide tells you how to install and operate the 3Com ONline™ Ethernet
24-Port 10BASE-T Module for the ONline System Concentrator. It also
includes i n formation on monitoring this module using an ONline network
mana gemen t mod ule . An a pp endi x ex pla ins ca blin g gu idel in es a nd op tion s
for this module.

Audience

This guide is intended for the following people at your site:

How to Use This Guide

❑ Network manager or administrator
❑ Hard ware installer

ONline Ethernet 24-Port 10BASE-T Module Installation Guide xiii

Structure of This Guide

This guide contains the following chapters:
Chapter 1, Introducti on – Introduces the functio ns and feature s of the

ONline Ethernet 24-Port 10BASE-T Mo dule.
Chapter 2, Designing and Expanding the Network – Shows possible

network c onfigurations using the ONline System Concentrator and the
ONline Ethernet 24-Port Module.

Chapter 3, Installing and Operating the Module – Provides illustrated
procedures for installing the 24-Port Module into the ONline System
Concentrator. Also shows front panel LEDs and dip switches on the
module and describes network management commands.

Chapter 4, T roubleshooting – Provides help in isolating and correcting
problems that may arise when installing or operating this module.

Appendix A, Specifications – Provides electrical, environmental, and
mechanic al specifications, plus information on 50-pin Telco-type
connectors, RJ-45 connectors, and twisted pair cables.

Appendix B, Technical Support – Lists the vario us methods for
contacting the 3Com technical support organization and for accessing
other product support se rvices.

Index

xiv ONline Ethernet 24-Port 10BASE-T Module Installation Guide

Document Conve ntions

The following document conventions are used in this manual:

Convention Indicates Example

Courier text User input In the Agent Information Form,

enter MIS in the New Contact
field.

System output After pressing the A pply

button, the sy stem displays
the message
Transmi tt in g da ta .

Bold command
string

Italic text in braces User-substituted

Capitalized text in
plain brackets

Italics Text emphasis,

Path names Before you begin, read the

identifiers

Keyboard entry
by the user

docu me nt titles

readme.txt file located in
/usr/snm/agents.

Use t he followin g command to
show port detail s:

SHOW PORT {

Type your password and press
[ENTER].

Ensure that you press the Apply
button after you add the new
search parameters.

slot

.all} VERBOSE

ONline Ethernet 24-Port 10BASE-T Module Installation Guide xv

Convention Indicates Example

Note: A Note. The

Caution: A Caution. A

Warning: A Warning. A

Related Docu me nts

This section provides information on supporting documentation, including:

❑ 3Com Documents

information is
important

condition may
damage
software or
hardware

condition may
threaten
personal safety

Note: Use STP lobe
cables for yo ur s yste m.

Caution: Do not put
your installation
diskettes on a
magnetic surface.
This may damage the
diskettes.

Warning: Wear eye
protec tion when
performing these
maintenance
procedures.

❑ Reference Documents

xvi ONline Ethernet 24-Port 10BASE-T Module Installation Guide

3Com Documents

The following documents provide ad ditional information on 3Com
products:

17-Slot ONline System Concentrator Installation and Operation
Guide – Explains how to install, operate, and manage the 3Com ONline

17-Slot Syste m Concentra tor (Models 5017C-LS and 5017 C with load
sharing).

6-Slot ONline System Concentrator Installation and Operation
Guide – Explains how to install, operate, and manage the 3Com ONline

6-Slot System Concentrator.
ONline Ethernet Management Module Installation and Operation Guide –

Describes h ow to install the ONline Ethernet Management Module in the
ONline System Concentrator and explains the LEDs on the module
faceplate. This guide also provides instructions for connecting a terminal to
the module and describes the management commands necessary to
perform man ag ement tasks on the concen trator and on remote device s.

ONline Management Commands Guide – Provides an alphabetize d
reference resource describing all ONline ma nagement commands.

For a complete list of 3Com documents, contact your 3Com representative.

Reference Documents

The following documents supply related background information:

Case, J., Fedor, M., Scoffstall, M., and J. Davin, The Simple Network
Management Protocol, RFC 1157, University of Tennessee at Knoxville,

Performan ce Systems International and the MIT Laboratory for Computer
Science, May 1990.

Rose, M., and K. McCloghrie, Structure and Identification of
Management Information for TCP/IP-based Internets, RFC 1155,

Performance Systems International and Hughes LAN Systems, Ma y 1990.

ONline Ethernet 24-Port 10BASE-T Module Installation Guide xvii

1

This chapter introduces you to the 3Com ONline™ Ethernet 24-Port
10BASE-T Modules (Mode l Numbers 5 124M-TPCL an d 5124M-TP). The
modules are re fe renced throughout this guide as the 24-Port Mo dule.

Introduction

You can install both versions of the 24-Port Module in all 3Com ONline
System Conce ntrator and ONcore

This chapter contains the following sections:

❑ Ethernet 24 -Port 10BASE-T Module Description
❑ Theory of Operation

Ethernet 24-Po rt 10BA SE- T Modu le Desc ript ion

This section describes:

❑ Module Features
❑ Model Number 5124M-TPCL Features
❑ Model Number 5124M-TP Features

®

Switching Hub models.

Introduction 1 - 1

The ONline Ethernet 24-Port Module is an IEEE 802.3 repeater module that
complies with the 10BASE-T standard. It connects up to 24 devices (PCs,
terminals, printers, modems) to the ONline System Concentrator.

The 24-Port Module (Model Num ber 5124M -TPCL and Model Number
5124M-TP) is a bank switching module. Bank swit ching is th e assi gnment of
a group of 12 consecutive ports to a single ne twork, or to an isolated
network .

Note: You cannot assign individual ports on the 5124M-TPCL and

the 5124M-TP modules to different networks.

Module Features

The ONline Ethernet 24-Port 10BASE-T Module:

❑ Is an IEEE 802.3 repeater module tha t complies with the 10BASE-T

standard.

❑ Connects up to 24 dev ic es (PCs, terminals, printers, m odems) to the

3Com ONline System Concentra tor or ONcore Switching Hub.

❑ Provides high port density at a low cost per port.
❑ Supports up to 100 meters on 10BASE-T-compliant unshielded twisted

pair (UTP) or shielded twisted pair (STP) wiring.

❑ Features “hot swap” capability so that you can install or remove the

module without having to power d own the conc entrator.

❑ Provides bank-switching capability.
❑ Provides a user-selectable autopartition threshold for flexibility in

dealing with collision-related network sl owdowns.

❑ Allows you to disable Link Integrity so you can connect to equipment

that does not conform to the 10BASE-T standard.

1 - 2 ONline Ethernet 24-Port 10BASE-T Module Installation Guide

❑ Is designed with all ports internally crossed over, as required by the

10BASE-T standard. This enables you to connect the 24-Port Module
to a 10BASE-T transceiver w ithout using an external crossover
adapter.

Bank Switching Capability

Bank switching is the assignment of a group of twelve consecutive ports to
a single n etwork, or to an isolated network.

In an unmanaged concentrator you can use DIP switches to:

❑ Assign all module ports to an Ethernet network or to an isolated

network

❑ Assign port groups 1 through 12 or 13 through 24 to different

Ethernet or isolated networks

In a managed concentrator you can use network management commands
to assign the following port “groups” to any of three backplane networks,
or to either of two isolated networks:

❑ Ports 1 through 12
❑ Ports 13 through 24
❑ All ports on the mo dule

Model Number 5124M-TPCL Features

Model Number 5124M-TPCL permits you to connect groups of 12
consecutive 10BASE-T-compliant module ports using:

❑ Two 50-pin Telco connectors (one connector attached to 12 ports)
❑ Two 25-pa ir 10 BA SE- T ca bles or two 12-leg “h ydra” cables ( one cable

per 12 ports)

Introduction 1 - 3

Model Number 5124M-TP Features

Model Number 5124M-TP permits you to connect individual
10BASE-T-compliant ports using 24 RJ-45 connectors (one connector per
port). The RJ-45 connectors provide direct connections to 10BASE-T cables
(one cable per connected port).

Theory of Operatio n

ONline E thernet 24-Port 10BASE-T Modules incorpora te repeate rs and
twisted pair transceivers that receive and restore amplitude to incoming
signals. 24 -Port Modul e repeaters restore phase and frequenc y.

Repeated signals:

❑ Synchron ize to the system clock
❑ Enter on the TriChannel® bac kp la ne of the ONline System

Concentrator.

Outgoing signals from the TriChannel backplane are:

❑ Sent directly to transceivers
❑ Transmitted to twisted pair link segments by the transceivers

1 - 4 ONline Ethernet 24-Port 10BASE-T Module Installation Guide

Figure 1-1 shows a 24-Port Module (Model Number 5124M-TPCL) connected
to nodes by means of bundled 25-pair or 12-leg hydra cables and patch
panels.

Concentrator

End Nodes

Patch Panels

Figure 1-1. Typic al 24-Port Module Configuration

Introduction 1 - 5

2

Designing and

Expanding t he Network

This chapter contains configuration information to help you design your
network . It describes how to configure networks us ing the ONli ne System
Concentrator and ONline Ethernet 24 -Port 10BASE-T Modules. It also
provides examples of network cabli ng structures and Ethernet n etwork
cabling solutions.

This chapter contains the following sections:

❑ Understanding the General Rules
❑ Choosing a Network Backbone Cabling Structure
❑ 24-Port Module Configura tio ns
❑ Using Patch Panels
❑ Establishing Fault-Tolerant Configurations

Note: To ensure proper operation of your network , install all

equipment using only approved cables. Refer to Appendix
A for information on cable requirem ents.

Designing and Expanding the Network 2 - 1

Understanding the General Rule s

This section describes general rules for configuring an Ethernet network
using fiber as the backbone medium. It also provides rules to ensure that
your network configuration conforms to distance limitations imposed by
Ethernet and networking equipment. Use these guidelines for building
your network.

Refer to the sections that follow for specific rules for:

❑ Dete rmining maximum 24-Port Module fiber link distances
❑ Connecting various horizontal media types (10BASE-FB, twisted pair)

to a 10BASE-FB backbone

❑ Exampl es of recommended fault-tolerant configurations

This section describes:

❑ Rules for Configuring a Network
❑ Calculating Equivale nt Fiber Dista nces

Rules for Configuring a Network

This section outlines seven basic network rules and 3Com
recommendations for building an Ethernet network.

2 - 2 ONline Ethernet 24-Port 10BASE-T Module Installation Guide

For more hardware-specific information on the 24-Port Module, refer to
Appendix A.

Table 2-1. Seven Basic Network Rules

Rule Definition Recommendations/Notes

1 If possible, use

10BASE-FB as the
backbone medium.

2 Wire the backbone in

a star topology to
isolate faults.

3 The maximum Fib er

Ethernet network
diameter is 4200
meters of fiber cable.

Use 62.5 micron cable to conform
with the IEEE 10B ASE-F and
upcoming ANSI FDDI standards.

Use ST-type con n ector s.
Make sure to lay extra fiber

cables. T he extr a cost is sma ll an d
you will find you need them as
your network grows.

The sta r t o po lo gy co nf o rms to
FDDI wiring as well -- just make
sure to run at leas t two fiber
strand s to ever y ba ckbo ne
connection.

The 4200 m ete rs is the ma ximu m
distanc e betw een an y tw o
transceivers on the network.

The 4200 meters does not include
the transceiver cable (that is, drop
or patch cable) that connects a
device wit h an exte rn al
transc eiver. T r ansceiver cables
can extend up to 50 meters. Thus,
total network diameter can be as
much as 4300 meters (4200 m + 2
* 50 m) betwe en any two node s.

Designing and Expanding the Network 2 - 3

Table 2-1. Seven Basic Network Rules (Continued)

Rule Definition Recommendations/Notes

4 Certain LAN devices

on the network shrink
the maximum Fiber
Ethernet network
diameter to less than
4200 meters.

5 Assume that one

meter of co axial or
twisted pair is equal to
one meter of fib er
cable.

Many LAN pro du cts de la y th e si gna l
that goes through them. This is
known a s equivalent distance. Ev ery
microsecond delay reduces the
maximum link distance. In fact,
every microsecond delay shrinks the
network diameter by approximately
200 meters of fiber cable. Table 2-2
lists the Equivalent Distances for
other 3Com products.

This is a conservative rule. For
example, the actual equivalence is
about 1.1 meters of coaxial for
every meter of fiber. For simplicity,
assume one meter.

2 - 4 ONline Ethernet 24-Port 10BASE-T Module Installation Guide

Table 2-1. Seven Basic Network Rules (Continued)

Rule Definition Recommendations/Notes

6 The f iber l ink dist ances

must not exceed the
limits imposed by the
optical power budget.

7 When in doubt, use a

bridge.

In genera l, on 62. 5 micr on cabl e,
you can go up to 4000 meters
point-to-point using the ONcore or
ONline Fiber Modules. If you have
poor quality cable or cross many
patch panels, you m ay have to
sacrifice some distance.

Some older Ethernet fiber optic
products are les s pow erf ul than
ONcore Fiber Module optics. So
when con nect ing to these
products, remember that the least
powerf ul devi ce det er mines the
maximu m p oin t-t o-p oint dist ance .

If you are not certain if you have
exceeded all owab le netw ork
distances, use a bridge to extend
the network.

Designing and Expanding the Network 2 - 5

LAN Equivalence

LAN equivalen ce is the sum of both the incoming and outgoing module
port signals . Different modules, however, have different equivalent
distances. Table 2-2 lists the LAN product equivalent distances.

Table 2-2. LAN Product Equivalent Distances

LAN Product

ONcore Ethernet 10-Port 10BASE-FB Module 190

Incoming signal to fiber port 140

Outgoing signal from fiber port 50

ONcore Ethernet 10BASE-T Module 585

Incoming signal to TP port 420

Outgoing signal from TP port 165

ONline Ethernet 10BASE-T Modules 585

Incoming signal to TP port 420

Outgoing signal from TP port 165

ONline Ethernet Fiber or 10BASE-FB Modules 190

Incoming signal to fiber port 140

Outgoing signal from fiber port 50

ONline Ethernet FOIRL Module 560

Equivalent

Distance (me ters )

Incoming signal to fiber port 330

Outgoing signal from fiber port 230

ONline Ethernet Transceiver Module 0
ORnet Star Coupler (8 or 14 port) 26 180

2 - 6 ONline Ethernet 24-Port 10BASE-T Module Installation Guide