Cabletron Systems 24 User manual

CABLETRON SYSTEMS, P. O. Box 5005, Rochester, NH 03866-5005
STH-22/-24/-42/-44
STACKABLE TOKEN RING HUB
USER’S GUIDE

NOTICE
iii
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
INFORMATIONCONTAINEDINIT,EVENIFCABLETRONSYSTEMSHAS
BEEN ADVISED OF, KNOWN, OR SHOULD HAVE KNOWN, THE
POSSIBILITY OF SUCH DAMAGES.
© Copyright February 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: 9031319 February 1996
STH , HubSTACK , and MicroMMAC are trademarks of Cabletron Systems,
Inc.
SPECTRUM , LANVIEW , and Remote LANVIEW , are registered
trademarks of Cabletron Systems, Inc.
IBM is a registered trademark of International Business Machines
Corporation.
CompuServe is a registered trademark of CompuServe, Inc.
DEC and VT100 are trademarks of Digital Equipment Corporation.
Windows is a registered trademark of Microsoft Corporation.
Printed On Recycled Pa
per

NOTICE
iv
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
likelyto causeinterference inwhich casethe userwill berequired tocorrect 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 Class A limits for radio noise
emissions from digital apparatus set out in the Radio Interference Regulations
of the Canadian Department of Communications.
Leprésentappareilnumérique n’émetpasdebruits radioélectriquesdépassant
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.

NOTICE
v
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. IF YOU 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. Youhavetherightto use onlythe one (1)copy of theProgram 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.

NOTICE
vi
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 EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF
MERCHANTABLITY AND FITNESS FOR A PARTICULAR PURPOSE, WITH
RESPECTTO THE PROGRAM, THEACCOMPANYING 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 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.

NOTICE
vii
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 03866

CONTENTS
ix
CONTENTS
CHAPTER 1 INTRODUCTION
1.1 Using This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 STH Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2.1 LANVIEW LEDs . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1.2.2 TCU Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1.2.3 Automatic Beacon Recovery Process . . . . . . . . 1-4
1.2.4 Support for Passive MAU Workgroups . . . . . . 1-4
1.3 Related Manuals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
1.4 Getting Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
CHAPTER 2 REQUIREMENTS & SPECIFICATIONS
2.1 General Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Cable Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2.3 UTP Cabling Specifications . . . . . . . . . . . . . . . . . . . . . . 2-3
2.3.1 UTP Cable Categories . . . . . . . . . . . . . . . . . . . . . 2-3
2.3.2 UTP Lobe Lengths . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2.4 STP Cabling Specifications . . . . . . . . . . . . . . . . . . . . . . . 2-5
2.4.1 STP Cable Categories. . . . . . . . . . . . . . . . . . . . . . 2-6
2.4.2 STP Lobe Lengths. . . . . . . . . . . . . . . . . . . . . . . . . 2-6
2.5 TCU Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
2.6 Operating Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
2.6.1 Ring Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
2.6.2 Ring Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
2.6.3 Power Supply Requirements . . . . . . . . . . . . . . . 2-9
2.6.4 Environmental Requirements . . . . . . . . . . . . . 2-10
2.6.5 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
2.6.6 Physical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

CONTENTS
x
CHAPTER 3 INSTALLATION
3.1 Unpacking the STH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.2 Installing the STH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.2.1 Rack Mount or Wall Mount Hardware. . . . . . . 3-1
3.2.2 Adding the STH to a Stack . . . . . . . . . . . . . . . . . 3-2
3.2.3 Attaching the Strain Relief Bracket . . . . . . . . . . 3-3
3.2.4 Rack-Mounting the STH . . . . . . . . . . . . . . . . . . . 3-3
3.2.5 Wall-Mounting the STH . . . . . . . . . . . . . . . . . . . 3-4
3.2.6 Free-Standing Installation. . . . . . . . . . . . . . . . . . 3-6
3.2.7 Connecting the STH to the Power Source . . . . 3-7
3.2.8 Attaching Network Cabling to TCU Ports . . . . 3-7
3.3 Finishing the Installation . . . . . . . . . . . . . . . . . . . . . . . . 3-8
CHAPTER 4 TROUBLESHOOTING
4.1 LANVIEW LED Signals . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.2 Trouble Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Page 1-1
CHAPTER 1
INTRODUCTION
Welcome to the Cabletron Systems STH-22/-24/-42/-44 Stackable Token
Ring Hub User’s Guide . The STH (Stackable Token Ring Hub) is a non-
intelligent hub designed to provide expanded connectivity for Cabletron
Systems’ STHi intelligent hubs and Cabletron Systems MicroMMAC
intelligent hubs. This manual provides installation instructions and
reference information for STH models 22, 24, 42, and 44.
Note : The term STH is used throughout this manual when describing
features and functions that are common to the above listed STH models.
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 STH. A general working knowledge of IEEE 802.5 Token Ring data
communications networks and their physical layer components will be
helpful when installing the STH.
Chapter 1, INTRODUCTION , outlines the contents of this manual,
briefly describes STH features, and concludes with a list of related
manuals.
Chapter 2, REQUIREMENTS & SPECIFICATIONS , describes
installation requirements, network guidelines, and STH operating
specifications.
Chapter 3, INSTALLATION , contains instructions for installing the STH.
Chapter 4, TROUBLESHOOTING , describes how to use the LANVIEW
LEDs to troubleshoot network problems.
1.2 STH Overview
The STH is a non-intelligent hub which provides expanded connectivity
for Cabletron Systems’ STHi intelligent hubs and Cabletron Systems
MicroMMAC intelligent hubs. Each STH added to an intelligent hub‘s
managed stack increases the LAN’s connectivity by 12 or 24 Trunk

STH Overview
Page 1-2
Connector Ports (TCUs) for connections to stations and other network
devices.
Figure 1-1. Front and Back Views of the STH-24
Up to four STH hubs can be linked to the same intelligent hub, bringing
the total direct connectivity potential to 120 managed TCU ports in the
stack. Intelligent hubs serve as the logical “top” of the stack and provide
full frame and error statistics for the collective stack, for each individual
device, and for each port. Hubs can be added to and removed from the
stack without powering-down any of the devices involved.
Cabletron’s HubSTACK Interconnect cables, Part Number 9380141, are
needed when stacking hubs.
The STH fully conforms to IEEE 802.5Token Ring specifications for
connectivity to Token Ring equipment. STH hubs offer:
• support for Cabletron Systems’ Automatic Beacon Recovery
Process (ABRP),
• Multiple Ring Out connectivity for Passive MAU workgroups,
• automatic speed fault protection,
• active filtering, re-timing, and repeating circuitry on all ports,
• and LANVIEW LEDs for “at-a-glance” diagnostic monitoring.
The STH does not have management capability and is not intended to be
used as a stand-alone device. Management must be provided by a
Cabletron Systems intelligent hub, either the STHi Stackable Token Ring
Hub with Intelligence or the MicroMMAC intelligent hub.
HubSTACK
STH-24
TOKEN RING HUB with LANVIEW®
SUPPORTING 100 OHM UTP CABLE
16Mb/s
PWR
STACK SPEED
4M 16M
STACK
RESERVED
STH-24 TOKEN RING HUB with LANVIEW®
SN
24X 23X 22X 21X 20X 19X 18X 17X 16X 15X 14X 13X
12X 11X 10X 9X 8X 7X 6X 5X 4X 3X 2X 1X

LANVIEW LEDs
Page 1-3
1.2.1 LANVIEW LEDs
Cabletron Systems’ LANVIEW Status Monitoring and Diagnostics
System is a troubleshooting tool. Conveniently located on the front panel,
LANVIEW LEDs help the user to quickly identify power failures,
beaconing conditions, cable faults, and link problems.
Refer to Section 4.1, LANVIEW LED Signals for more information on the
LANVIEW LED visual status monitoring system.
1.2.2 TCU Ports
Each STH, depending on the STH model (see Table 1-1. ), is equipped
with 12 or 24 TCU ports, each fitted with a female RJ45 modular
connector jack to support the attachment of either STP (shielded twisted
pair) or UTP (unshielded twisted pair) cabling with RJ45 connector plugs.
Models that support STP cabling use RJ45 connectors that provide a
grounded connection for the cabling shield.
Lobe Port and Multiple Ring Out Port Configurations
Each TCU port on the STH is internally defaulted to operate as a lobe
interface to support the insertion of a Token Ring station into a ring.
However, each TCU port may also be reconfigured, via the intelligent
hub’s Local Management (LM) application, to function as a Ring Out port
to support the connection of non-intelligent, passive MAU (Multi-Station
Access Unit) workgroups. See Section 1.2.4, Support for Passive MAU
Workgroups .
Ring Speed Fault Protection
STH hubs also provide Ring Speed Fault Protection on each TCU port to
protect against beaconing conditions caused by stations inserted at the
Table 1-1. Port and Media List for
STH
Models
STH
-22 12 - Unshielded RJ45 ports
STH -24 24 - Unshielded RJ45 ports
STH -42 12 - Shielded RJ45 ports
STH -44 24 - Shielded RJ45 ports

Automatic Beacon Recovery Process
Page 1-4
wrong ring speed. If a ring speed mismatch is detected, the STH disables
the port to keep the misconfigured station isolated from the ring and
provides a simple visible LED signal (blinking red at the port’s LED) to
indicate to the user that Speed Fault Protection has disabled the port. The
port remains disabled until the ring speed mismatch condition is
removed or resolved.
Active Circuitry
On each TCU port, STH hubs provide active circuitry which filters,
equalizes, and amplifies all received signals before transmitting them to
the next point on the ring. The result is enhanced signal integrity and
extended maximum station lobe cable distances.
Daughter Board Upgrade Kit
Both the STH-22 and the STH-42 can be upgraded to 24 ports using the
following daughter board upgrade kits:
• TR-UTP-UGKT for STH-22.
• TR-STP-UGKT for STH-42.
1.2.3 Automatic Beacon Recovery Process
To guard against interruptions in network operations due to beaconing
conditions, the STH supports Cabletron Systems’ advanced Automatic
Beacon Recovery Process which automatically partitions problematic
lobes from the ring, allowing the rest of the ring to continue operating.
(ABRP engages even before the IEEE standard beacon recovery process
begins and is able to treat conditions beyond the scope of the IEEE
process.) It is the stack’s intelligent hub that actually executes the ABRP
algorithm. The intelligent hub also checks partitioned lobes periodically
and re-enables them automatically once they have recovered.
1.2.4 Support for Passive MAU Workgroups
Whereas a station signals a TCU to open its interface by sending a
phantom current down its lobe cable, a passive Multi-Station Access Unit
can not provide phantom current. A TCU Ring Out port is therefore
configured to ignore the absence of phantom current in the connecting
cable and to look instead for the presence of data bits to determine link
status.

Related Manuals
Page 1-5
By default, each of the STH hub’s TCU ports is configured to its STN
(station) setting to support concentrator lobe connections to stations.
Through Local Management, any TCU port may be reconfigured to its
RO (Ring Out) setting to support connections to passive MAU (Multi-
Station Access Unit) workgroups.
Improved Protection from Beaconing
The STH provides enhanced reliability for existing networks which use
passive MAUs because Multiple Ring Out TCUs allow for the separate
attachment of each MAU. Rather than daisy-chaining MAUs together as a
single entity and risking their collective isolation in case of beaconing, the
user can now attach each MAU individually, reducing the number of
MAU ports that are at risk of collective isolation in case of beaconing on
the ring; ABRP is able to bypass individually connected MAUs on an
individual rather than collective basis. See Figure 1-2.
No Connection Redundancy
The STH hub’s Ring Out TCU configuration does not provide for the
MAU’s redundant connection to the ring. In the common configuration, a
MAU chain is dual-attached to the Token Ring LAN via both a Ring Out
cable and a Ring In cable. Using a TCU port, however, each passive MAU
workgroup is physically connected to the hub in the same manner as a
station—by a single cable—and therefore is not provided a backup path
between the MAU and the Token Ring network. Only the dual
attachment of Ring In and Ring Out cables can provide a backup path.
This level of connectivity must be provided by a dedicated pair of Ring In
/ Ring Out ports such as those available on the intelligent hub.
1.3 Related Manuals
Use the STHi User’s Guide (PN 9031390) and the MicroMMAC-xxT
User’s Guide (PN 9031320) to supplement the procedures and other
technical data provided in this manual.

Related Manuals
Page 1-6
Figure 1-2. Improved Beacon Recovery Resolution for MAUs
(8 Stations)
(8 Stations)
(8 Stations)
(8 Stations)
STH TCUs
Ring
Out
Ring
Out
Ring
Out
Ring
Out
Multi-Station
Access Units
Ring
In
Ring
In
Ring
In
Ring
In
When each MAU is individually connected to the STH hub,
only one MAU must be bypassed
to isolate the hub from a beaconing MAU station.
The 8 stations on that MAU still go down,
but the remaining MAUs and their stations stay operational.
(8 Stations)
(8 Stations)
(8 Stations)
(8 Stations)
Multi-Station
Access Units
Hub with
Ring In / Ring Out
Ring
Out
Ring
Out
Ring
Out
Ring
Out
Ring
In
Ring
In
Ring
In
Ring
In
Ring
Out
Ring
In
When MAUs are daisy-chained,
they are connected as single collective entity.
The entire chain must be bypassed
to isolate the hub from a single beaconing station.
All stations lose connection if beaconing occurs on any station.
DAISY-CHAIN MAU CONFIGURATION
RING OUT TCU MAU CONFIGURATION

Getting Help
Page 1-7
1.4 Getting Help
If you need additional support related to the Cabletron Systems STH, or if
you have any questions, comments, or suggestions concerning this
manual, contact Cabletron Systems Technical Support:
By phone: [phone]
Monday-Friday; 8am - 8pm EST
By CompuServe
®
: GO CTRON from any ! prompt
By Internet mail: [email protected]
By Fax: [phone]
By BBS: [phone]
By mail: Cabletron Systems, Inc.
P.O. Box 5005
Rochester, NH 03866-5005

Page 2-1
CHAPTER 2
REQUIREMENTS & SPECIFICATIONS
This chapter describes network guidelines, power requirements, and
operating specifications for the STH. Before installing the STH, read this
chapter and confirm that the network meets the requirements and
conditions specified in this chapter. Failure to follow these guidelines
could result in poor network performance.
2.1 General Considerations
All devices connected to the STH must meet IEEE 802.5 Token Ring
specifications.
Maximum Number of Stations on a Ring
The maximum stack composed of four 24-port STH hubs and one 24-port
intelligent hub offers a total of 120 TCU ports, but the number of ports
available on the LAN may be increased by the use of passive Multi-
station Access Units (MAUs) (refer to Section 1.2.4,
Support for
Passive MAU Workgroups ). The recommended maximum number of
stations in a single ring is 250 stations when using STP lobe cabling and
150 stations when using UTP cabling anywhere on the ring.
Crosstalk
Crosstalk is interference caused by signal coupling between different
cable pairs contained within a multi-pair cable bundle. Multi-pair cables
should not be used for UTP lobe cabling. Avoid mixing Token Ring
signals with other applications (voice, etc.) within the same cable.
Noise
Noise can be caused by either crosstalk or externally induced impulses.
Outside systems (motors, switching equipment, fluorescent lighting, high
amperage equipment) may produce electrical interference causing noise.
The number and quality of cable connections also contribute considerably
to noise levels. If noise induced errors are suspected, it may be necessary

General Considerations
Page 2-2
to re-route cabling away from potential noise sources, or to ensure that
the electrical wiring in the area is properly wired and grounded, or to
replace connectors along affected segments.
Temperature
The attenuation of PVC-insulated cable varies significantly with
temperature. Check the cable manufacturer’s specifications. Plenum-
rated cables are strongly recommended in areas where temperatures
exceed 40˚C. Under such conditions, plenum-rated cables ensure that
cable attenuation remains within specifications.
Installation Recommendations
In addition to complying with the cable specifications presented in
Sections 2.2 and 2.3, the cabling installation should comply with the
following recommendations to obtain optimum performance from the
network:
• UTP cabling should be free of splices, stubs, or bridged taps.
• No more than two punch-down blocks should exist between TCU
ports and wall outlets.
• Metal troughs, ducts, etc. carrying Token Ring signals should be
properly grounded.
• Cables should be routed away from sources of electrical noise, such as
power lines, fluorescent lights, electric motors, radio interference, and
heavy machinery.
• Token Ring signals should not be routed through UTP cables that exit
a building or which are adjacent to cables either exiting a building or
exposed to lightning strikes and power surges.
• UTP cables that contain Token Ring signals should not be
simultaneously used for applications which may impress high
voltages (greater than 5 volts) with sharp rise or fall times, since the
noise coupling from such signals could directly cause errors on the
Token Ring network.
• For single telecommunications closet rings, lobe lengths should not
exceed 100 meters of 22 to 24 AWG wire from the attaching device and
the TCU port.

Cable Specifications
Page 2-3
• Where practical, dedicated cable should be used for Token Ring
signals.
• Work area wall plates and outlets used for the Token Ring network
should be clearly labeled as Token Ring network lobe connections.
2.2 Cable Specifications
Take care in planning and preparing the cabling and connections for the
network. The susceptibility of the LAN’s cables to crosstalk and noise
determines the network’s error rate, and thus, the reliability of data
propagation on the network. The quality of the connections, the length of
cables and other conditions of the installation are critical factors in
determining the reliability of the network.
2.3 UTP Cabling Specifications
Both UTP supporting modules (STH-22 / 24) support D-inside wiring
(DIW) voice grade Unshielded Twisted Pair (UTP) cable as described
below and in EIA SP-1907B . All category 5, all category 4, and some (see
Section 2.3.2,
UTP Lobe Lengths , on page 5) category 3 UTP cables
meet Token Ring network performance requirements.
2.3.1 UTP Cable Categories
Both UTP concentrator modules (STH-22 / 24) support UTP cables
classified as category 3, 4, and 5.
UTP cable is categorized according to the following specifications:

UTP Cable Categories
Page 2-4
Category 3 consists of (usually) four Unshielded Twisted Pairs of
24 AWG solid wire for data or voice communication. (IBM Type 3 is
coincidentally the same as UTP Category 3.) It is typically used to wire
cable runs within the walls of buildings. In some installations, pre-
existing UTP building wiring can be used for Token Ring cabling.
Warning: At 16 Mb/s ring speeds, some Category 3 cable does not meet
the performance requirements of a Token Ring network. This may
impose lower limits on lobe cable distances and ring node counts. See
Table 2-1.
Categories 4 and 5 are higher quality versions of category 3. They use the
same gauge of wire but demonstrate superior performance due to
improvements in material quality and assembly (e.g. more twists per
foot).
Warning: Because Near-End Crosstalk (NEXT) contributes the
majority of its detrimental effects near the end of a lobe cable, the
quality of jumper cables and patch cables is most critical. Seek the
highest practical grade. The quality of connectors and terminators is
also critical.
Warning: Telephone Battery and Ringing voltages used in UTP
telephone circuits could present a shock hazard and can damage Token
Ring equipment if connected to Token Ring cabling. DO NOT connect
Table 2-1. UTP Cable Category Specifications
UTP
Cat. Operating Frequency Electrical Impedance
Signal
Attenuation
per 100m
NEXT
loss
(@ ≥ 100m)
34 MHz
≤100Ω±15% ≤5.6 dB ≥32 dB
16 MHz ≤100Ω±15% ≤13.1 dB ≥23 dB*
44 MHz ≤100Ω±15% ≤4.3 dB ≥47 dB
16 MHz ≤100Ω±15% ≤8.9 dB ≥38 dB
54 MHz ≤100Ω±15% ≤4.3 dB ≥63 dB
16 MHz ≤100Ω±15% ≤8.2 dB ≥44 dB
*below Token Ring performance requirement of ≥30.5 dB.

UTP Lobe Lengths
Page 2-5
UTP cabling to any non-Token Ring network conductors
(telephone, etc.) or ground. If in doubt, test wiring before using.
2.3.2 UTP Lobe Lengths
The physical length of the cable connecting a station to a TCU port on the
concentrator is referred to as the lobe length. The maximum lobe length
attainable with the concentrator, under ideal conditions, is shown in Table
2-2. Cable routing, connector attenuation, noise, and crosstalk can
adversely affect the maximum lobe length.
Some UTP category 3 cables fail to meet the performance minimums
required to support a Token Ring network. Whereas category 3 allows for
near end crosstalk (NEXT) loss as low as 23 dB per 100 m at 16 Mb/s,
Token Ring performance requirements demand a NEXT loss of at least
30.5 dB. To safeguard against worst case conditions (running at 16 Mb/s
and using category 3 cable with the category’s lowest qualifying NEXT
loss—23 dB), the recommended maximum lobe length should be reduced
to keep crosstalk interference within acceptable levels when using
category 3 cable.
2.4 STP Cabling Specifications
Both STP concentrator modules (STH-42 / 44) support all STP cables
classified as IBM Types 1, 2, 6, and 9. All cables meeting the criteria for
classification as IBM Type 1, 2, 6, or 9 meet Token Ring network
performance requirements.
Table 2-2. UTP Maximum Lobe Lengths.
UTP
Category
@ 4 Mb/s @ 16 Mb/s
meters (feet) meters (feet)
3 200 (656) 100* (328)*
4 225 (738) 110 (360)
5 250 (820) 120 (393)
* for cable with NEXT loss ≥30.5 dB per 100m