Cabletron Systems CRBRIM-W/E User Manual

CRBRIM-W/E

USER’S GUIDE

NOTICE

Cabletron Systems reserves the right to make changes in specifications and other
information contained in this document without prior notice. The reader should in all cases
consult Cabletron Systems to determine whether any such changes have been made.

The hardware, firmware, or software described in this manual is subject to change without
notice.

IN NO EVENT SHALL CABLETRON SYSTEMS BE LIABLE FOR ANY
INCIDENTAL, INDIRECT, SPECIAL, OR CONSEQUENTIAL DAMAGES
WHATSOEVER (INCLUDING BUT NOT LIMITED TO LOST PROFITS) ARISING
OUT OF OR RELATED TO THIS MANUAL OR THE INFORMATION CONTAINED
IN IT, EVEN IF CABLETRON SYSTEMS HAS BEEN ADVISED OF, KNOWN, OR
SHOULD HAVE KNOWN, THE POSSIBILITY OF SUCH DAMAGES.

© Copyright October 1994 by:
Cabletron Systems, Inc.
P.O. Box 5005
Rochester, NH 03866-5005

All Rights Reserved
Printed in the United States of America

Part Number: 9031246 October 1994

SPECTRUM
EMME, EMM-E6, ESXMIM, MMAC-8FNB, MMAC-5FNB
MicroMMAC, NBR-420/620

Ethernet
VT-220
CompuServe

and

LANVIEW

is a registered trademark of Xerox Corp.

and

VT-320

are trademarks of Digital Equipment Corp.

is a registered trademark of CompuServe, Inc.

are registered trademarks and

, and

EPIM

are trademarks of Cabletron Systems, Inc.

CRBRIM-W/E, EPIM-3PS,

Printed on

recycled paper.

, and

MMAC-3FNB

,

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Hardware Installation Guide

i

-i

Notice

FCC NOTICE

This device complies with Part 15 of the FCC rules. Operation is subject to the following
two conditions: (1) this device may not cause harmful interference, and (2) this de vice must
accept any interference received, including interference that may cause undesired
operation.

NOTE:

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 uses, generates, and can radiate radio frequency
energy and if not installed in accordance with the operator’s manual, may cause harmful
interference to radio communications. Operation of this equipment in a residential area is
likely to cause interference in which case the user will be required to correct the
interference at his own expense.

WARNING:

approved by the party responsible for compliance could void the user’s authority to operate
the equipment.

This equipment has been tested and found to comply with the limits for a Class A

Changes or modifications made to this device which are not expressly

DOC NOTICE

This digital apparatus does not exceed the Class A limits for radio noise emissions from
digital apparatus set out in the Radio Interference Regulations of the Canadian Department
of Communications.

Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la class A prescrites dans le Règlement sur le
brouillage radioélectrique édicté par le ministère des Communications du Canada.

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CRBRIM-W/E

CABLETRON SYSTEMS, INC.

PROGRAM LICENSE AGREEMENT

Notice

IMPORTANT:

This document is an agreement between you, the end user, and Cabletron Systems, Inc.
(“Cabletron”) that sets forth your rights and obligations with respect to the Cabletron
software program (the “Program”) contained in this package. The Program may be
contained in firmware, chips or other media. BY UTILIZING THE ENCLOSED
PRODUCT, YOU ARE AGREEING TO BECOME BOUND BY THE TERMS OF THIS
AGREEMENT, WHICH INCLUDES THE LICENSE AND THE LIMITATION OF
WARRANTY AND DISCLAIMER OF LIABILITY. IF YOU DO NOT AGREE TO THE
TERMS OF THIS AGREEMENT , PROMPTL Y RETURN THE UNUSED PRODUCT TO
THE PLACE OF PURCHASE FOR A FULL REFUND.

Before utilizing this product, carefully read this License Agreement.

CABLETRON SOFTWARE PROGRAM LICENSE

1. LICENSE.
in this package subject to the terms and conditions of this License Agreement.

You have the right to use only the one (1) copy of the Program pro vided

You may not copy, reproduce or transmit any part of the Program except as permitted

by the Copyright Act of the United States or as authorized in writing by Cabletron.

2. O
disassemble the Program.

3. APPLICABLE LA
under the laws and in the state and federal courts of New Hampshire. You accept the
personal jurisdiction and venue of the New Hampshire courts.

THER RESTRICTIONS. You may not reverse engineer, decompile, or

W. This License Agreement shall be interpreted and governed

Hardware User’s Guide

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iii

Notice

EXCLUSION OF WARRANTY

AND DISCLAIMER OF LIABILITY

1. EXCLUSION OF
Cabletron in writing, Cabletron makes no warranty, expressed or implied, concerning the
Program (including Its documentation and media).

CABLETRON DISCLAIMS ALL WARRANTIES, OTHER THAN THOSE
SUPPLIED TO YOU BY CABLETRON IN WRITING, EITHER EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF
MERCHANTABLITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH
RESPECT TO THE PROGRAM, THE ACCOMPANYING WRITTEN MATERIALS,
AND ANY ACCOMPANYING HARDWARE.

2. NO LIABILITY FOR CONSEQ
CABLETRON OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES
WHATSOEVER (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS OF
BUSINESS, PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS
INFORMATION, SPECIAL, INCIDENTAL, CONSEQUENTIAL, OR RELIANCE
DAMAGES, OR OTHER LOSS) ARISING OUT OF THE USE OR INABILITY TO USE
THIS CABLETRON PRODUCT, EVEN IF CABLETRON HAS BEEN ADVISED OF
THE POSSIBILITY OF SUCH DAMAGES. BECAUSE SOME STATES DO NOT
ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR
CONSEQUENTIAL OR INCIDENTAL DAMAGES, OR ON THE DURATION OR
LIMITATION OF IMPLIED WARRANTEES IN SOME INSTANCES THE ABOVE
LIMITATIONS AND EXCLUSIONS MAY NOT APPLY TO YOU.

WARRANTY. Except as may be specifically provided by

UENTIAL DAMAGES. IN NO EVENT SHALL

UNITED STATES GOVERNMENT RESTRICTED RIGHTS

The enclosed product (a) was developed solely at private expense; (b) contains “restricted
computer software” submitted with restricted rights in accordance with Section 52227-19
(a) through (d) of the Commercial Computer Software - Restricted Rights Clause and its
successors, and (c) in all respects is proprietary data belonging to Cabletron and/or its
suppliers.

For Department of Defense units, the product is licensed with “Restricted Rights” as
defined in the DoD Supplement to the Federal Acquisition Regulations, Section 52.227­7013 (c) (1) (ii) and its successors, and use, duplication, disclosure by the Government is
subject to restrictions as set forth in subparagraph (c) (1) (ii) of the Rights in T echnical Data
and Computer Software clause at 252.227-7013. Cabletron Systems, Inc., 35 Industrial
Way, Rochester, New Hampshire 03867.

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CRBRIM-W/E

Contents

Chapter 1 Introduction

1.1 Using This Manual............................................................................1-2

1.2 Document Objectives.......................................................................1-2

1.3 Document Organization....................................................................1-2

1.4 Document Conventions....................................................................1-3

1.5 Related Manuals .............................................................................. 1-5

1.6 Getting Help ..................................................................................... 1-5

Chapter 2 Product Overview

2.1 System Specifications......................................................................2-2

2.2 Memory Configurations....................................................................2-3

Chapter 3 Preparing for Installation

3.1 Preventing Electrostatic Discharge Damage....................................3-1

3.2 System Operation Prerequisites.......................................................3-2

3.3 Distance Limitations.........................................................................3-2

3.3.1 Serial Connections............................................................3-2

3.4 Interference Considerations.............................................................3-4

3.5 Console Considerations...................................................................3-5

3.5.1 Console Port Connections................................................3-5

3.6 Network Connection Considerations................................................3-6

3.6.1 Ethernet Connections.......................................................3-6

3.6.2 Serial Connections............................................................3-6

3.7 Inspecting the System......................................................................3-7

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Contents

Chapter 4 Installation

4.1 Tools and Parts Required.................................................................4-1

4.2 Installing the CRBRIM-W/E.............................................................. 4-2

4.2.1 Installing a CRBRIM-W/E into a MIM................................4-3

4.2.2 Installing the EPIM-3PS....................................................4-4

4.2.3 Connecting the CRBRIM-W/E to the EPIM-3PS...............4-5

4.3 Making External Connections...........................................................4-6

Chapter 5 Troubleshooting the Hardware

Configuration

5.1 Problem Solving............................................................................... 5-2

5.1.1 Troubleshooting the Network Interfaces and Cables........5-2

5.1.2 Reading LED Indicators....................................................5-3

Chapter 6 Maintenance

6.1 Installing Primary-Memory DRAM SIMMs........................................6-1

6.1.1 Tools and Equipment Required........................................ 6-2

6.1.2 Primary Memory Configurations.......................................6-2

6.1.3 Approved DRAM SIMMs...................................................6-3

6.1.4 DRAM SIMM Installation...................................................6-3

6.2 Replacing System-Code SIMMs ...................................................... 6-5

6.2.1 Tools and Equipment Required........................................ 6-5

6.2.2 System-Code SIMM Replacement ................................... 6-5

6.3 Recovering a Lost Password............................................................6-7

Appendix A Cabling Specifications

Console Port Signals and Pinouts.........................................................A-2

Serial Cable Assemblies and Pinouts.....................................................A-3

EIA-530......................................................................................A-3

RS-232.......................................................................................A-5

RS-449.......................................................................................A-8

V.35 ........................................................................................A-11

X.21 ........................................................................................A-14

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Contents

Appendix B Virtual Configuration Register

Virtual Configuration Register Settings...................................................B-1

Changing Configuration Register Settings.................................B-3

Virtual Configuration Register Bit Meanings..............................B-4

Enabling Booting from Flash......................................................B-8

Copying to Flash........................................................................B-8

Appendix C Bootstrap Program

Entering the Bootstrap Program.............................................................C-1

Available Bootstrap Commands.................................................C-2

Running the Diagnostics............................................................C-5

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vii

Chapter 1

Introduction

Welcome to the Cabletron Systems CRBRIM-W/E User’s Guide. This manual
describes features, explains installation procedures, and provides specifications for
the Cabletron Systems CRBRIM-W/E. The CRBRIM-W/E is designed to reside
in, and provide additional connectivity/functionality to, various Cabletron MIMs
and hubs (e.g., the EMM-E6, ESXMIM, NBR-420/620 or MicroMMAC).

Figure 1-1. CRBRIM-W/E

Hardware User’s Guide

S0

S1

SYS S1

LANPWR

RESET

Hardware Installation Guide

CONSOLE

TP

S0

1-1

1-1

CHAPTER 1: Introduction

1.1 Using This Manual

Read through this manual completely to familiarize yourself with its content and
to gain an understanding of the features and capabilities of the CRBRIM-W/E. A
general working knowledge of data communications networks and their physical
layer components is helpful when using the CRBRIM-W/E.

1.2 Document Objectives

This publication will step you through initial site preparation, installation, and
troubleshooting. It also covers selected maintenance procedures.

1.3 Document Organization

The major sections of this publication follow:

• Chapter 1, “Introduction” outlines the contents, and describes the objectives

and conventions of the

chapter also provides a list of related manuals and

information.

• Chapter 2, “Product Overview, ” contains an o v erview of the router feature set

and physical specifications.

• Chapter 3, “Preparing for Installation, ” includes safety recommendations, site

requirements, an installation checklist, console and auxiliary port cable

connection considerations, network connection considerations, and

instructions for inspecting the new system.

• Chapter 4, “Installation,” provides a list of tools and parts required,

procedures for making external connections, and information about what to

do after installing the hardware.

• Chapter 5, “Troubleshooting the Hardware Configuration,” briefly discusses

troubleshooting, problem solving, and reading LED indicators.

• Chapter 6, “Maintenance,” includes procedures for upgrading system code

SIMMs, replacing DRAM SIMMs, and recovering from a lost password.

CRBRIM-W/E Hardware Installation Guide

GETTING HELP

. This

1-2

CRBRIM-W/E

Document Conventions

• Appendix A, “Cabling Specifications,” provides cable illustrations and
pinouts for the console port and serial cables.

• Appendix B, “Virtual Configuration Register,” discusses the settings for and
functions of the virtual configuration register.

• Appendix C, “Bootstrap Program,” contains procedures for testing system
memory and the central processor unit (CPU) by using the bootstrap
diagnostic tests and command options.

1.4 Document Conventions

This publication uses the following conventions to convey instructions and
information:

Command descriptions use these conventions:

• Commands and keywords are in

• Variables for which you supply values are in

boldface

font.

italic

font.

• Elements in square brackets ([ ]) are optional.

• Alternative but required keywords are grouped in braces ({ }) and are
separated by a vertical bar ( | ).

Examples use these conventions:

• Terminal sessions are in

• Information you enter is in

screen

font.

boldface screen

font.

• Nonprinting characters are shown in angle brackets (< >).

• Information the system displays is in

screen

font, with default responses in

square brackets ([ ]).

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3

CHAPTER 1: Introduction

Means reader take note. Notes contain helpful suggestions or

NOTE

references to materials not contained in this manual.

Means the described action saves time. You can save time by

TIP

performing the action described in the paragraph.

Means reader be careful. You are capable of doing something that
might result in equipment damage or loss of data.

!

CAUTION

WARNING

Means danger. You are in a situation that could cause bodily
injury . Befor e you work on any equipment, be awar e of the hazards
involved with electrical circuitry and standard practices for
preventing accidents.

1-4

CRBRIM-W/E

Related Manuals

1.5 Related Manuals

Use the following manuals to supplement the procedures and data provided in this
manual. This manual references procedures in these manuals, when appropriate,
but does not repeat them.

Cabletron Systems’
Cabletron Systems’
Cabletron Systems’
Cabletron Systems’
Cabletron Systems’
Cabletron Systems’
Cabletron Systems’
Cabletron System’s

(A compilation of Cisco Systems® Router Products Configuration
and Reference Guides)

EMM-E6 Installation Guide
EMM-E6 Local Management Guide
ESXMIM User’s Guide
ESXMIM Local Management Guide
MicroMMAC User’s Guide
NBR-620/420/220 User’s Guide
NBR-620/420/220 Local Management Guide
CRM-DOC

Set

1.6 Getting Help

If you need additional support related to the Cabletron Systems CRBRIM-W/E, or
if you have any questions or comments related to this manual, contact Cabletron
Systems Technical Support by:

Mail: Cabletron Systems, Inc.,

P.O. Box 5005

Rochester, NH 03866-5005
Phone: [phone], Mon-Fri 8AM to 8PM EST
CompuServe®: GO CTRON from any ! prompt
Internet Mail: [e-mail]

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5

Chapter 2

Product Overview

Bridge/Router Interface Modules (BRIMs) reside in, and provide additional
connectivity/functionality to, various Cabletron MIMs and hubs (e.g. the EMM­E6 or MicroMMAC). Cabletron’s CRBRIM-W/E remote access router provides
multi-protocol router capability for Cabletron MMAC (Multi-Media Access
Center) modules with BRIM and EPIM (Ethernet Port Interface Module) slots.

The CRBRIM-W/E utilizes a fixed configuration of two WAN ports, and one
internal Ethernet port. The two high density WAN ports support V.35, X.21,
RS449, RS422, RS530, and RS232 interfaces. The CRBRIM-W/E uses Cisco
Systems ® routing software and is capable of supporting Frame Relay , X.25, DDN
X.25, SMDS, T1/E1, and DDS circuit connections.

The CRBRIM-W/E uses a FLASH EEPROM and is shipped with system code
operating from Flash memory by default. (For more information on system-code
operation, see Chapter 3, section 3.2 “System Operation Prerequisites.”)

Figure 2-1 shows a front view of the CRBRIM-W/E.

RESET

S1 S0

LANPWR SYS

S1

S0

CONSOLE

Figure 2-1. CRBRIM-W/E

Sections of this chapter follow:

• System Specifications

• Memory Configurations

• Protocol Support

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2-1

CHAPTER 2: Product Overview

This publication takes you through the initial har dwar e installation

NOTE

and selected maintenance procedures. Refer to your specific MIM
or Management Module Installation Guides and Local
Management Guides for software configuration and operating
information.

2.1 System Specifications

System specifications of the CRBRIM-W/E are listed in Table 2-1.

Table 2-1. System Specifications

Description Design Specification

Dimensions H x W x D 3x12.5x15.5cm
Current

Power dissipation
Processor 20-MHz Motorola 68EC030
Network interface 1 Ethernet and 2 synchronous serial (2501)
Ethernet interface (internal) IEEE 802.3 (CRBRIM to EPIM-3PS)
Synchronous serial

interfaces

Console ports Asynchronous serial (RJ-45)
Operating environment 32 through 104°F (0 through 40°C)
Nonoperating temperature –40 through 185°F (–40 through 85°C)

1.0 to 0.5 amps (A)
40W (max.), 135.5 British thermal units (Btu)/hr

RS-232, RS-449, V.35, X.21 (NRZ/NRZI
DTE/DCE
EIA-530 (NRZ/NRZI and DTE mode)
All serial interfaces use the DB-60 connector at
the chassis.

2

mode)

1

and

Operating humidity 5 through 95%, noncondensing
Noise level 34 dBa @ 3' (0.914 m)

1. NRZ = Nonreturn to zero. NRZI = Nonreturn to zero inverted.

2. DTE = Data terminal equipment. DCE = Data communications equipment.

2-2

CRBRIM-W/E

Memory Configurations

2.2 Memory Configurations

The CRBRIM-W/E has the following memory systems:

• Primary memory (main memory)—Dynamic random-access memory

(DRAM) that stores the running configuration and routing tables; mounted on
the system card.

• Shared memory—Shared DRAM that is used for packet buffering by the

router network interfaces.

• System-code memory—Flash or programmable read-only memory (PROM);

stores the operating system software image.

• Boot ROM memory—Stores a subset of the operating system software image

that is called the system bootstrap image or the bootstrap program (or ROM
monitor). The system bootstrap image allows you to boot the router when
Flash memory does not contain a valid system image.

The boot ROM prompt follo ws: Router(boot)>. The bootstrap program (R OM
monitor) prompt is the greater than sign (>), which dif fers from the user-le vel
operating-system prompt of gateway >. (For more information, see Appendix
B, “Virtual Configuration Register,” and Appendix C, “Bootstrap Program.”

• Nonvolatile random-access memory (NVRAM)—Stores the system

configuration file and the virtual configuration register.

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CHAPTER 2: Product Overview

Table 2-2 shows possible memory configurations for the CRBRIM-W/E.

Table 2-2. Memory Configurations

Memory Type Memory Capacity

Primary memory (DRAM SIMMs) 1 MB (expandable to 4 or 16 MB)
Shared (packet) memory 1 MB (DRAM on board)
System-code memory (Flash or

PROMs)
Boot ROM 1 MB
Nonvolatile RAM (NVRAM) 32 KB

1. The router has 2 MB of permanent (fixed) DRAM memory and a DRAM SIMM
socket for upgrading the memory. 1 MB of this permanent memory is used by the
CPU and is called
work interface ports to store packets and is called
a DRAM SIMM is installed in the DRAM SIMM socket, all of the DRAM memory on
this SIMM becomes primary memory for the CPU, and the 2 MB of DRAM that is
permanent on the board becomes shared memory.

primary

memory. The other 1 MB of memory is used by the net-

4 MB (expandable)

shared

or

packet

1

memory. When

2.3 Protocol Support

The CRBRIM-W/E is hardware encoded at the factory to operate with one of three
router software sets. This provides users with the option of selecting IP,

DESKTOP, or ENTERPRISE routing software at the time of purchase.

The CRBRIM-W/E is factory configured for either IP, DESKTOP

NOTE

or ENTERPRISE Routing Softwar e. The factory har dware settings
are permanent and cannot be changed to operate a differ ent r outer
software set.

2-4

CRBRIM-W/E

Protocol Support

The ENTERPRISE router software set provides all Cisco-supported LAN, WAN,
and routing protocols as well as IBM features and protocol translator functionality .
Supported LAN protocols include IP, Novell, IPX, DECnet IV, AppleTalk Phase 1
and 2, bridging, DECnet V, XNS, Banyon VINES, OSI, Apollo Domain, PUP, and
CHA OSnet.

The DESKTOP software set supports IP, Novell, IPX, DECnet IV, AppleTalk
Phase 1 and 2, and bridging.

The IP software set supports IP, and bridging protocols.

CRBRIM-W/E models configured for either DESKTOP or

NOTE

ENTERPRISE Routing Software are shipped with a user
installable 4 megabyte primary memory DRAM SIMM. See
Chapter 6, section 6.1.4 DRAM SIMM Installation for installation
procedur es.

All CRBRIM-W/E models are shipped with Frame Relay and X.25 software that
offers efficient remote site access to packet switched networks.

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5

Chapter 3

Preparing for Installation

This chapter describes the tasks you must perform before starting actual system
installation.

Sections of this chapter follow:

• Preventing Electrostatic Discharge Damage

• System Operation Prerequisites

• Distance Limitations

• Interference Considerations

• Console Considerations

• Network Connection Considerations

• Inspecting the System

3.1 Preventing Electrostatic Discharge Damage

Electrostatic discharge (ESD) damages equipment and impairs electrical circuitry.
It occurs when electronic components are improperly handled and causes
complete or intermittent failures.

Follow ESD-pre vention procedures when handling electronic components. Ensure
that the chassis is electrically connected to earth ground. Wear an ESD wrist strap,
ensuring that it makes good skin contact. Connect the clip to an unpainted chassis
frame surface to safely channel unwanted ESD voltages to ground. To properly
guard against ESD damage and shocks, the wrist strap and cord must operate
effectively. If no wrist strap is available, ground yourself by touching the metal
part of the chassis.

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CHAPTER 3: Preparing for Installation

For safety, periodically check the resistance value of the antistatic
strap, which should be within the range of 1 and 10 MΩ.

!

CAUTION

3.2 System Operation Prerequisites

The CRBRIM-W/E is designed to run system code from Flash memory single in­line memory modules (SIMMs). With the proper system code image, the router
also can be run from dynamic random-access memory (DRAM); however, this
operation requires a 4-MB memory upgrade (installation of a 4 MB x 72 pin
DRAM SIMM). Further, operating system code from DRAM can result in a 25­percent decrease in system performance.

Operating the system code from Flash is the default and is recommended for
optimum performance of the router.

3.3 Distance Limitations

When setting up your router, consider distance limitations and potential
electromagnetic interference (EMI) as defined by the Electronic Industries
Association (EIA). Following are the distance limitation specifications for serial
interfaces.

3.3.1 Serial Connections

As with all signaling systems, RS-232 signals travel a limited distance at any
given bit rate; generally, the slower the data rate, the greater the distance.
Table 3-1 shows the standard relationship between baud rate and maximum
distance.

3-2

CRBRIM-W/E

Distance Limitations

Table 3-1. IEEE Standard RS-232 Transmission Speed Versus Distance

!

CAUTION

Baud Rate

2400 200 60
4800 100 30
9600 50 15
19200 25 7.6
38400 12 3.7

Distance
(Feet)

Distance
(Meters)

RS-232 is often used in violation of these specifications. If you
understand the electrical problems that can arise and can
compensate for them, you might be able to get good results at
distances greater than those shown in Table 3-1; however, do so at
your own risk. We recommend that you stay within the standard­defined distance.

Balanced drivers allow RS-449 signals to travel greater distances than RS-232.
Table 3-2 lists the standard relationship between baud rate and maximum distance
for RS-449 signals. These limits are also valid for V.35 and X.21.

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CHAPTER 3: Preparing for Installation

Table 3-2. IEEE Standard RS-449 Transmission Speed Versus Distance

!

CAUTION

Baud

Rate

2400 4100 1250
4800 2050 625
9600 1025 312
19200 513 156
38400 256 78
56000 102 31
T1 50 15

Distance

(Feet)

Distance

(Meters)

The RS-449 and V.35 interfaces support data rates up to 2.048
Mbps. Exceeding this maximum is not recommended; do so at your
own risk.

3.4 Interference Considerations

When you run cables for any significant distance in an electromagnetic field,
interference can occur between the field and the signals on the cables. This fact
has two implications for the construction of terminal plant cabling:

• Plant cabling can emanate radio interference if it is unshielded for too long a
distance.

• Strong electromagnetic interference (EMI) (e.g. lightning or radio
transmitters) can destroy the RS-232 drivers and receivers in the server.

If you use twisted-pair cables with a good distribution of grounding conductors in
your plant cabling, emitted radio interference is unlikely. If you exceed the
maximum distances, ground the conductor for each data signal; however, this
practice is not recommended.

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CRBRIM-W/E