Cabletron Systems SEHI SEHI100TX- User manual

SEHI100TX-22 100BASE-T
INTELLIGENT STACKABLE HUB
USER’S GUIDE
®
SEHI Book Page 1 Wednesday, May 15, 1996 10:42 AM

SEHI100TX User’s Guide i
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 1996 by Cabletron Systems, Inc., P.O. Box 5005, Rochester, NH 03866-5005
All Rights Reserved
Printed in the United States of America
Order Number: 9031511-01 April 1996
SPECTRUM , LANVIEW and BRIM are registered trademarks and Element Manager , EPIM ,
EPIM-100FX , EPIM-100TX , HubSTACK , MicroMMAC , SEH , and SEHI are trademarks of
Cabletron Systems, Inc.
All other product names mentioned in this manual may be trademarks or registered trademarks of
their respective companies.
Printed on Recycled Paper
SEHI Book Page i Wednesday, May 15, 1996 10:42 AM

Notice
ii SEHI100TX User’s Guide
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 device must accept any
interference received, including interference that may cause undesired operation.
NOTE: 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 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: Changes or modifications made to this device which are not expressly approved by the
party responsible for compliance could void the user’s authority to operate the equipment.
DOC NOTICE
This digital apparatus does not exceed the ClassA 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.
VCCI NOTICE
This equipment is in the 1st Class Category (information equipment to be used in commercial and/or
industrial areas) and conforms to the standards set by the Voluntary Control Council for Interference
by Information Technology Equipment (VCCI) aimed at preventing radio interference in commercial
and/or industrial areas.
Consequently, when used in a residential area or in an adjacent area thereto, radio interference may be
caused to radios and TV receivers, etc.
Read the instructions for correct handling.
SEHI Book Page ii Wednesday, May 15, 1996 10:42 AM

Notice
SEHI100TX User’s Guide iii
CABLETRON SYSTEMS, INC. PROGRAM LICENSE AGREEMENT
IMPORTANT: Before utilizing this product, carefully read this License Agreement.
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. IFYOU DO NOT
AGREE TO THE TERMS OF THIS AGREEMENT, PROMPTLY RETURN THE UNUSED
PRODUCT TO THE PLACE OF PURCHASE FOR A FULL REFUND.
CABLETRON SOFTWARE PROGRAM LICENSE
1. LICENSE. You have the right to use only the one (1) copy of the Program provided in this
package subject to the terms and conditions of this License Agreement.
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. OTHER RESTRICTIONS. You may not reverse engineer, decompile, or disassemble the
Program.
3. APPLICABLE LAW. This License Agreement shall be interpreted and governed 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.
EXCLUSION OF WARRANTY AND DISCLAIMER OF LIABILITY
1. EXCLUSION OF WARRANTY. Except as may be specifically provided by 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 EXPRESSED OR IMPLIED, INCLUDING
BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO THE PROGRAM, THE
ACCOMPANYING WRITTEN MATERIALS, AND ANY ACCOMPANYING HARDWARE.
2. NO LIABILITY FOR CONSEQUENTIAL DAMAGES. IN NO EVENT SHALL
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
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LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES, OR
ON THE DURATION OR LIMITATION OF IMPLIED WARRANTIES, IN SOME
INSTANCES THE ABOVE LIMITATIONS AND EXCLUSIONS MAY NOT APPLY TO
YOU.
SEHI Book Page iii Wednesday, May 15, 1996 10:42 AM

Notice
iv SEHI100TX User’s Guide
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 52.227-7013 (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 Technical Data and Computer Software clause at
252.227-7013. Cabletron Systems, Inc., 35 Industrial Way, Rochester, New Hampshire 03867-0505.
SEHI Book Page iv Wednesday, May 15, 1996 10:42 AM

SEHI100TX User’s Guide v
CONTENTS
CHAPTER 1 INTRODUCTION
1.1 Using This Manual.......................................................................1-1
1.2 Document Conventions...............................................................1-2
1.3 Getting Help.................................................................................1-3
1.4 Related Manuals..........................................................................1-3
CHAPTER 2 SEHI FEATURES AND OPTIONS
2.1 SEHI Overview............................................................................2-1
2.2 SEHI Features.............................................................................2-2
2.3 Stackable Capabilities.................................................................2-3
2.4 Rack Mounting Capabilities.........................................................2-4
2.5 Remote Network Management....................................................2-4
2.6 Optional 100BASE-TX and 100BASE-FX EPIMs........................2-4
CHAPTER 3 INSTALLATION REQUIREMENTS
AND SPECIFICATIONS
3.1 Cable Specifications....................................................................3-1
3.1.1 HubSTACK Interconnect Cable Requirements...............3-1
3.1.2 UTP Cable Specifications...............................................3-2
3.1.3 Multimode Specifications for the EPIM-100FX ...............3-3
3.2 Network Cable Lengths...............................................................3-4
3.3 Network Port Specifications.........................................................3-5
3.4 COM Port Requirements.............................................................3-5
3.5 Operating Specifications..............................................................3-6
3.5.1 Power Supply Requirements ..........................................3-6
3.5.2 Environmental Requirements .........................................3-6
3.6 Agency Approvals........................................................................3-7
3.7 Physical Specifications................................................................3-7
CHAPTER 4 INSTALLATION
4.1 Unpacking the SEHI....................................................................4-1
4.2 Pre-Installation Checkout ............................................................4-2
4.3 Tabletop or Shelf Installation.......................................................4-3
4.4 Rackmount Installation................................................................4-4
4.5 Powering Up and Stacking the SEHI...........................................4-7
4.6 Installing the EPIM-100TX or the EPIM-100FX...........................4-9
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Contents
vi SEHI100TX User’s Guide
CHAPTER 5 CONNECTING TO THE NETWORK
5.1 Connecting the SEHI to the Network ...........................................5-1
5.1.1 Connecting to Network Ports...........................................5-1
5.1.2 Connecting a UTP Segment to an EPIM-100TX.............5-2
5.1.3 Connecting a Fiber Segment to the EPIM-100FX...........5-4
5.2 Testing the Installation.................................................................5-5
CHAPTER 6 TROUBLESHOOTING
6.1 Installation Test............................................................................6-1
6.2 Using LANVIEW...........................................................................6-2
6.3 Using the RESET Button .............................................................6-4
6.4 Setting the NVRAM Switch ..........................................................6-5
CHAPTER 7 LOCAL MANAGEMENT
7.1 Local Management Keyboard Conventions.................................7-2
7.2 Management Terminal Setup.......................................................7-3
7.3 Accessing Local Management.....................................................7-6
7.4 The Feature Selection Screen .....................................................7-7
7.5 The Community Name Table Screen...........................................7-8
7.5.1 Editing the Community Name Field.................................7-9
7.6 The Configuration Screen..........................................................7-10
7.6.1 Setting the IP Address...................................................7-12
7.6.2 Setting the Subnet Mask...............................................7-12
7.6.3 Setting the Default Gateway..........................................7-13
7.6.4 Using the Port Enable Override.....................................7-13
7.6.5 Exiting the Configuration Screen...................................7-14
7.7 The Trap Table Screen..............................................................7-14
7.7.1 Configuring the Trap Table............................................7-15
7.7.2 Exiting the Trap Table Screen.......................................7-15
7.8 The SNMP Tools Screen ...........................................................7-16
7.8.1 Getting Individual OIDs .................................................7-18
7.8.2 Getting the Next OID.....................................................7-18
7.8.3 Setting an OID...............................................................7-18
7.8.4 Viewing Multiple OIDs...................................................7-19
7.8.5 Walking Through OIDs..................................................7-19
7.8.6 Stepping Through OIDs.................................................7-20
7.8.7 Cycling Through OIDs...................................................7-20
7.8.8 Exiting the SNMP Tools Screen....................................7-20
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Contents
SEHI100TX User’s Guide vii
7.9 The Device Statistics Screen.....................................................7-21
7.9.1 Selecting the Appropriate Module/Port.........................7-23
7.9.2 Using the ENABLE PORT Command...........................7-24
7.9.3 Using the DISABLE PORT Command..........................7-24
7.9.4 Exiting the Device Statistics Screen .............................7-24
APPENDIX A EPIM SPECIFICATIONS
A.1 EPIM Specifications.....................................................................A-1
A.1.1 EPIM-100TX....................................................................A-1
A.1.2 EPIM-100FX....................................................................A-2
APPENDIX B IMAGE FILE DOWNLOAD USING OIDS
B.1 Setting Up a UNIX Workstation as a TFTP Server......................B-2
B.2 Standard Local Download ...........................................................B-3
INDEX
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SEHI100TX User’s Guide 1-1
CHAPTER 1
INTRODUCTION
Welcome to the Cabletron Systems SEHI100TX-22 100BASE-T
Intelligent Stackable Hub User’s Guide
. This manual provides
installation instructions, troubleshooting, and reference information for
the SEHI100TX-22.
1.1 USINGTHIS MANUAL
Read through this manual to gain an understanding of the features and
capabilities of the SEHI. A general knowledge of Ethernet and IEEE
802.3u type data communications networks and their physical layer
components is helpful when installing the SEHI.
Chapter 1,
Introduction , outlines the contents and describes the
objectives and conventions of this manual. This chapter also provides
getting help information and concludes with a list of related manuals.
Chapter 2,
SEHI Features and Options , briefly describes SEHI features
and provides information about available options.
Chapter 3, Installation Requirements and Specifications , provides
installation requirements, network guidelines, and SEHI specifications.
Chapter 4, Installation , contains instructions for installing the SEHI as a
stackable or standalone hub.
Chapter 5, Connecting to the Network , explains how to connect the
SEHI to the network using the various media types.
Chapter 6, Troubleshooting , describes how to use the LANVIEW LEDs
to troubleshoot network problems.
Chapter 7, Local Management , describes how to use SEHI Local
Management screens and the available commands.
NOTE
The term SEHI (Stackable Ethernet Hub with Intelligence) is
used throughout this manual when describing the features and
functions of the SEHI100TX-22.
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Chapter 1: Introduction
1-2 SEHI100TX User’s Guide
Appendix A, EPIM Specifications , provides specifications, cabling
information, and switch settings for the Ethernet Port Interface Modules.
Appendix B, Image File Download Using OIDs , provides instructions
for setting up a TFTP server and downloading an image file to the SEHI
by setting specific MIB OID strings.
1.2 DOCUMENT CONVENTIONS
The following conventions are used throughout this document:
NOTE
Note symbol. Calls the reader’s attention to any item of
information that may be of special importance.
TIP
Tip symbol. Conveys helpful hints concerning procedures or
actions.
!
CAUTION
Caution symbol. Contains information essential to avoid
damage to the equipment.
Warning symbol.Warns against an action that could result in
equipment damage, personal injury or death.
SEHI Book Page 2 Wednesday, May 15, 1996 10:42 AM

Getting Help
SEHI100TX User’s Guide 1-3
1.3 GETTING HELP
If you need additional support related to this device, or if you have any
questions, comments, or suggestions concerning this manual, contact
Cabletron Systems Technical Support:
By phone [phone]
Monday – Friday; 8
A . M . – 8 P . M . Eastern Time
By CompuServe GO CTRON from any ! prompt
By Internet mail [email protected]
By FTP ctron.com (134.141.197.25)
Login
anonymous
Password your email address
Before calling Cabletron Systems Technical Support, have the following
information ready:
• A description of the failure
• A description of any action(s) already taken to resolve the problem
(e.g., changing mode switches, rebooting the unit, etc.)
• A description of your network environment (layout, cable type, etc.)
• Network load and frame size at the time of trouble (if known)
• The serial and revision numbers of all Cabletron Systems products in
the network
• The device history (i.e., have you returned the device before, is this a
recurring problem, etc.)
• Any previous Return Material Authorization (RMA) numbers
1.4 RELATED MANUALS
Use the Cabletron Systems SEH100TX-22 100BASE-T User’s Guide to
supplement the procedures and other technical data provided in this
manual. The procedures contained in the
SEH100TX-22 100BASE-T
User’s Guide
are referenced where appropriate, but not repeated in this
manual.
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SEHI100TX User’s Guide 2-1
CHAPTER 2
SEHI FEATURES AND OPTIONS
This chapter provides an overview of the SEHI and contains sections
detailing features and available options.
Figure 2-1 The SEHI100TX-22
2.1 SEHI OVERVIEW
The SEHI100TX-22 is an intelligent repeating hub providing 22 RJ45
ports and one Ethernet Port Interface Module (EPIM) port on the front
panel for network connections. The SEHI has two rear panel HubSTACK
Interconnect Bus ports for stackable connections. The SEHI100TX-22 is
designed to manage the Cabletron Systems non-intelligent stackable hub,
the SEH100TX-22.
NOTE
The terms SEHI (Stackable Ethernet Hub with Intelligence) and
SEH (Stackable Ethernet Hub) are used throughout this
manual when describing the features and functions of the
SEHI100TX-22 and the SEH100TX-22.
PWR
CPU
CLN
HubSTACK 100BASE-TX HUB WITH LANVIEW®
SEHI100TX-22
22X 21X 20X 19X 18X 17X
11X 10X 9X 8X 7X 6X
16X 15X 14X 13X 12X
5X 4X 3X 2X 1X
E
1
A
RCV
LNK
RCV
LNK
22 21 20 19 18 17 16 15 14 13 12
11 10 9 8 7 6 5 4 3 2 1
EPIM 1
Port Status LEDs
System LEDs
COM Port
RESET Button
Network Ports 1-22
EPIM Slot
Interconnect Bus "OUT" Port
Interconnect Bus "IN" Port
FRONT VIEW
SEHI100TX-22 100BASE-T HUB WITH LANVIEW®
SN SEH100TX INTERCONNECT
OUT
1511_18
IN
Power Supply
REAR VIEW
NET.
ADD.
COM
RESET
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Chapter 2: SEHI Features and Options
2-2 SEHI100TX User’s Guide
2.2 SEHI FEATURES
Repeater Functionality
The SEHI fully conforms to the IEEE 802.3u Repeater specifications. The
SEHI transmits retimed data packets, regenerates the preamble, extends
fragments, and arbitrates collisions.
The SEHI100TX-22 meets IEEE 802.3u Repeater Class I standards.
Class I standards allow one repeater between any two Data Terminal
Equipment (DTE) devices within a single collision domain (network).
The SEHI automatically partitions problem segments, and reconnects
repaired segments to the network. This feature minimizes the impact on
network operation resulting from a problem on one segment by isolating
the problem segment. Only devices on the problem segment are affected.
When the problem is solved, the SEHI automatically reconnects the
isolated segment to the network.
Polarity Detection and Correction
Each twisted pair port on the SEHI incorporates a polarity detection and
correction feature that allows the SEHI to pass data regardless of the
polarity of the twisted pair segment’s receive link.
FLASH EEPROMs
The SEHI uses FLASH EEPROMs that allow the downloading of new
and updated firmware using Cabletron Systems SPECTRUM Element
Manager/Windows or any device using BOOTP or TFTP protocols.
!
CAUTION
The SEHI100TX-22 operates in a 100BASE-T Ethernet
network.This product will NOT operate in a 10BASE-T
environment. Connect the SEHI100TX-22 and SEH100TX-22
only to similar 100BASE-T products.
The SEHI100TX-22 supports the EPIM-100TX and the
EPIM-100FX. No other Cabletron Systems EPIMs operate in
this device.
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Stackable Capabilities
SEHI100TX User’s Guide 2-3
LANVIEW LEDs
Cabletron Systems LANVIEW status monitoring and diagnostics system
is a troubleshooting tool that helps in diagnosing power failures,
collisions, cable faults, and link problems. The LANVIEW LEDs are
conveniently located on the SEHI front panel.
RESET Button
Resetting the hub with the front panel RESET Button reboots the SEHI
and initializes the processor. Resetting the SEHI also resets all of the SEH
non-intelligent hubs in the stack.
Local Management
Manage the SEHI and its attached segments through Local Management
on the SEHI. Local Management provides full packet and error statistics
for the entire stack, individual device, or individual port. Access Local
Management by attaching a DEC VT320 terminal or a PC using VT320
emulation software to the RJ45 COM port on the SEHI. Cabletron
Systems provides a UTP console cable with RJ45 connectors at each end,
adaptors for DB9 or DB25 connections and an instruction sheet with
adaptor pinout information with the SEHI. Chapter 7,
Local
Management
, provides detailed information on setting up and managing
your network through Local Management.
2.3 STACKABLE CAPABILITIES
The SEHI100TX-22 intelligent hub is designed to manage a stack of up to
four Cabletron Systems SEH100TX-22 non-intelligent hubs. The SEHI is
placed at the bottom of the stack. It manages all SEH hubs in the stack
and provides full packet and error statistics for the entire stack, individual
device, or individual port.
Stack up to four SEH non-intelligent hubs with one SEHI using the
Cabletron Systems external HubSTACK Interconnect cables provided
with each SEH. Stackable configurations make it possible to maintain
only one IEEE repeater hop while providing up to 120 ports. Hubs can be
added or removed from the stack without having to power down the entire
stack.
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Chapter 2: SEHI Features and Options
2-4 SEHI100TX User’s Guide
2.4 RACK MOUNTING CAPABILITIES
The SEHI can be installed in a 19-inch rack. Cabletron Systems provides
brackets and mounting screws with the SEHI. See Chapter 4,
Installation , for complete rack mounting instructions.
2.5 REMOTE NETWORK MANAGEMENT
Manage the SEHI remotely with any SNMP network management
system. Cabletron Systems offers the following remote management
packages:
• Cabletron Systems SPECTRUM
• Cabletron Systems SPECTRUM Element Manager/Windows
• Cabletron Systems Remote SPECTRUM Portable Management
Applications
• Third Party SNMP compliant Network Management Packages
2.6 OPTIONAL 100BASE-TX and 100BASE-FX EPIMs
100BASE-TX and 100BASE-FX EPIMs are not included with the SEHI
but can be purchased separately from Cabletron Systems.
EPIMs enable the expansion of a network through different types of
media. Cabletron Systems offers two optional EPIMs for the
SEHI100TX-22 and the SEH100TX-22 as shown in Table 2-1.
Table 2-1 100BASE-TX/FX EPIMs
EPIM MediaType Connector
EPIM-100TX Category 5 UTP Cable RJ45
EPIM-100FX Multimode Fiber Optic Cable SC
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SEHI100TX User’s Guide 3-1
CHAPTER 3
INSTALLATION REQUIREMENTS
AND SPECIFICATIONS
This Chapter describes cabling requirements, network guidelines, and
operating specifications for the SEHI100TX-22.
3.1 CABLE SPECIFICATIONS
The front panel SEHI100TX-22 network ports support Category 5
Unshielded Twisted Pair (UTP) cabling. Ethernet Port Interface Modules
(EPIMs) expand the network using UTP (EPIM-100TX) or multimode
fiber optic (EPIM-100FX) cabling. For information concerning the two
EPIM types, refer to Appendix A. The rear panel Interconnect Bus ports
support Cabletron Systems Interconnect cables for stackable applications.
Take care in planning and preparing the network cabling and connections.
The quality of the connections and the length of cables are critical factors
in determining the reliability of the network. The following sections
describe specifications for each media type.
3.1.1 HubSTACK Interconnect Cable Requirements
Attach the SEHI to the stacked SEH modules with the HubSTACK
Interconnect cables provided with each SEH and available only from
Cabletron Systems (P/N 9380209). The cable attaches to the SEHI rear
panel bus “OUT” port. The SEHI must be placed at the bottom of the
stack. Stack up to four SEH hubs together with one SEHI.
!
CAUTION
The network must meet the requirements and conditions
specified in this chapter to obtain satisfactory performance from
this equipment.Failure to follow these guidelines could result in
poor network performance.
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Chapter 3: Installation Requirements and Specifications
3-2 SEHI100TX User’s Guide
3.1.2 UTP Cable Specifications
The device at the other end of the twisted pair segment must meet IEEE
802.3u 100BASE-T specifications. When connecting a 100BASE-TX
Twisted Pair Segment to the SEHI twisted pair network ports and the
EPIM-100TX module, the network must meet the following
requirements:
Length
The IEEE 802.3u 100BASE-T standard requires that 100BASE-TX
devices be capable of transmitting over a 100 meter (328 foot) link using
Category 5 UTP wire.
Impedance
UTP cables typically have an impedance of between 85 to 110 ohms.
Jitter
Intersymbol interference and reflections cause jitter in the bit cell timing,
resulting in data errors.A 100BASE-TX link must not generate more than
1.4 ns of jitter. If the cable meets the impedance requirements for a
100BASE-TX link, jitter should not be a concern.
Crosstalk
Crosstalk is caused by signal coupling between the different cable pairs
contained within a multi-pair cable bundle. 100BASE-TX transceivers are
designed so that the user does not need to be concerned about cable
crosstalk, provided the cable meets all other requirements.
Noise
Noise is caused by either crosstalk or externally induced impulses.
Impulse noise may cause data errors if the impulses occur at very specific
times during data transmission. Generally, the user need not be concerned
about noise. If noise-related data errors are suspected, it may be necessary
to either reroute the cable or eliminate the source of the impulse noise.
SEHI Book Page 2 Wednesday, May 15, 1996 10:42 AM

Cable Specifications
SEHI100TX User’s Guide 3-3
Propagation Delay
Propagation delay is the amount of time it takes data to travel from the
sending device to the receiving device. Total propagation delay allowed
for the network is 256 bit times (2.56 µs) in one direction (5.12 µs round
trip). If the total propagation delay between any two nodes on the network
exceeds 2.56 µs, then use bridges or other devices to further segment the
network.
Temperature
The attenuation of PVC insulated cable varies significantly with
temperature. At temperatures greater than 40°C (104°F), Cabletron
Systems recommends the use of plenum-rated cables to ensure that cable
attenuation remains within specification.
3.1.3 Multimode Specifications for the EPIM-100FX
The SEHI supports the Cabletron Systems EPIM-100FX. The
EPIM-100FX meets IEEE 802.3u standards. When connecting a fiber
optic segment to the SEHI EPIM-100FX module, the network must meet
the following requirements:
Cable Loss
Test the fiber optic cable with a fiber optic attenuation test set adjusted for
an 850 nm wavelength. This test verifies that the signal loss in a cable is
within an acceptable level. The maximum loss for a multimode fiber optic
cable is 11.0 dB.
Fiber Optic Budget and Propagation Delay
Determine the maximum fiber optic cable length by calculating the fiber
optic budget delay and total network propagation before fiber optic cable
runs are incorporated in any network design.
Fiber optic budget is the combination of the optical loss due to the fiber
optic cable, in-line splices, and fiber optic connectors.
Propagation delay (collision delay) is the amount of time it takes data to
travel from the sending device to the receiving device. Total propagation
delay allowed for the entire network is 256 bit times (2.56 µs) in one
direction (5.12 µs round trip). If the total propagation delay between any
two nodes on the network exceeds 2.56 µs, then use bridges or other
devices to further segment the network.
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Chapter 3: Installation Requirements and Specifications
3-4 SEHI100TX User’s Guide
3.2 NETWORK CABLE LENGTHS
This section details the maximum network cable lengths specified by the
IEEE 802.3u standard for a Class I repeater. As stated previously, the
physical size of the network is limited primarily by propagation delay.
The round trip delay cannot exceed 512 bit times or 5.12 µs.
A 100BASE-T network might use all UTP links, all fiber links or a
combination of both. Table 3-1 details the maximum link lengths for each
type and combination of cable when used with a Class I repeater.
Figure 3-1 shows a simplified example of a network with one Class I
repeater. Link segments A and B represent the longest links in the
network. In this case, if both segment A and segment B are UTP, each
segment may be up to 100 meters long for a maximum network length of
200 meters. If segmentA is UTP and segment B is fiber, the maximum
length of the network is 263 meters (with a maximum UTP segment
length of 100 meters). If both segmentsA and B are fiber, the maximum
length is 274 meters.
NOTE A stack of five SEH hubs or four SEH hubs and one SEHI hub
is equivalent to one repeater.
!
CAUTION
The maximum length of an individual UTP segment may be no
more than 100 meters.
Table 3-1 Maximum Class I Network Cable Length
Number of
Repeaters UTP UTP & Fiber Fiber
1 200 m 263 m 274 m
SEHI Book Page 4 Wednesday, May 15, 1996 10:42 AM

Network Port Specifications
SEHI100TX User’s Guide 3-5
Figure 3-1 Class I Network
3.3 NETWORK PORT SPECIFICATIONS
The SEHI network ports use shielded RJ45 connectors that support UTP
cabling. Figure 3-2 shows the RJ45 pinouts.
Figure 3-2 RJ45 Network Ports
3.4 COM PORT REQUIREMENTS
The RJ45 COM port supports access to a Local Management Console.
The COM port supports a Digital Equipment CorporationVT320 terminal
or PC emulation of the VT320 terminal. Figure 3-3 shows the pinouts for
the RJ45 COM port.
SEHI100TX-22
Repeater
DTE DTE
AB
1 2 3 4 5 6 7 8
1. Receive + 5. Not Used
2. Receive - 6. Transmit -
3. Transmit + 7. Not Used
4. Not Used 8. Not Used
11X 10X 9X
09162_02
SEHI Book Page 5 Wednesday, May 15, 1996 10:42 AM