Cabletron Systems 100BASE-FX Cabling Manual
Cabletron Systems
Cabling Guide
Notice
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
Printed in the United States of America.
Order Number: 9031845-02E1 December 1996
Cabletron Systems, Inc.
P.O. Box 5005
Rochester, NH 03866-5005
Cabletron Systems , SPECTRUM , BRIM , DNI , FNB , LANVIEW , Multi Media Access Center , are
registered trademarks, and Bridge/Router Interface Modules , BRIM-A100 , Desktop Network
Interface , EPIM , EPIM-3PS , EPIM-A , EPIM-C , EPIM-F1 , EPIM-F2 , EPIM-F3 , EPIM-T , EPIM-T1 ,
EPIM-X , Media Interface Module , MicroMMAC , MIM , MMAC , MMAC-3FNB , MMAC-5FNB ,,
MMAC-M8FNB , MMAC-Plus , RMIM , SPECTRUM Element Manager , SPECTRUM for Open
Systems , are trademarks of Cabletron Systems, Inc.
All other product names mentioned in this manual may be trademarks or registered trademarks of
their respective companies.
1996 by Cabletron Systems, Inc. All rights reserved.
i
Notice
ii
Chapter 1 Introduction
Using This Guide.........................................................................................................................1-1
Document Organization ............................................................................................................. 1-1
Document Conventions..............................................................................................................1-3
Warnings and Notifications ................................................................................................1-3
Formats ..................................................................................................................................1-3
Additional Assistance .................................................................................................................1-4
Related Documentation .............................................................................................................. 1-4
Contents
Chapter 2 Cabling Terms
Physical Components..................................................................................................................2-1
Media......................................................................................................................................2-1
Cable.......................................................................................................................................2-1
Wire.........................................................................................................................................2-2
Connector ..............................................................................................................................2-3
Port .........................................................................................................................................2-6
Test Characteristics ......................................................................................................................2-6
Chapter 3 Relevant Specifications
EIA/TIA........................................................................................................................................3-1
Universal Service Order Code (USOC) ....................................................................................3-2
National Electrical Code (NEC)................................................................................................. 3-2
Chapter 4 Ethernet Media
Cabling Types ............................................................................................................................... 4-1
Attachment Unit Interface (AUI) .......................................................................................4-1
Coaxial Cable ........................................................................................................................4-3
Unshielded Twisted Pair (UTP)..........................................................................................4-5
Fiber Optics .........................................................................................................................4-14
Connector Types ........................................................................................................................4-17
AUI .......................................................................................................................................4-17
Coaxial Cable ......................................................................................................................4-19
UTP Cable............................................................................................................................4-23
Fiber Optics .........................................................................................................................4-28
iii
Chapter 5 Ethernet Network Requirements
10BASE-T ......................................................................................................................................5-1
Cable Type .............................................................................................................................5-1
Insertion Loss (Attenuation) ...............................................................................................5-1
Impedance .............................................................................................................................5-2
Jitter.........................................................................................................................................5-2
Delay.......................................................................................................................................5-2
Crosstalk ................................................................................................................................5-3
Noise.......................................................................................................................................5-3
Other Considerations...........................................................................................................5-3
Length.....................................................................................................................................5-4
10BASE-F (Multimode)...............................................................................................................5-4
Cable Type .............................................................................................................................5-4
Attenuation............................................................................................................................5-5
Insertion Loss ........................................................................................................................5-5
Delay.......................................................................................................................................5-5
Length.....................................................................................................................................5-6
Ethernet FOIRL (Single Mode)...................................................................................................5-6
Cable Type .............................................................................................................................5-6
Attenuation............................................................................................................................5-6
Insertion Loss ........................................................................................................................5-7
Delay.......................................................................................................................................5-7
Length.....................................................................................................................................5-7
10BASE2 ........................................................................................................................................5-8
Cable Type .............................................................................................................................5-8
Termination............................................................................................................................5-8
Connectors/Taps ..................................................................................................................5-8
Grounding .............................................................................................................................5-9
Length.....................................................................................................................................5-9
10BASE5 (Coaxial Cable)............................................................................................................5-9
Cable Type .............................................................................................................................5-9
Termination............................................................................................................................5-9
Connectors/Taps ................................................................................................................5-10
Grounding ...........................................................................................................................5-10
Length...................................................................................................................................5-10
Chapter 6 Full-Duplex Ethernet Network Requirements
Full-Duplex 10BASE-T................................................................................................................6-1
Cable Type .............................................................................................................................6-1
Insertion Loss (Attenuation) ...............................................................................................6-2
Impedance .............................................................................................................................6-2
Jitter.........................................................................................................................................6-2
Delay.......................................................................................................................................6-2
Crosstalk ................................................................................................................................6-3
Noise.......................................................................................................................................6-3
Other Considerations...........................................................................................................6-3
Length.....................................................................................................................................6-4
iv
10BASE-F (Multimode)...............................................................................................................6-4
Cable Type .............................................................................................................................6-4
Attenuation............................................................................................................................6-5
Insertion Loss........................................................................................................................6-5
Delay.......................................................................................................................................6-5
Length ....................................................................................................................................6-6
Ethernet FOIRL (Single Mode) ..................................................................................................6-6
Cable Type .............................................................................................................................6-6
Attenuation............................................................................................................................6-6
Insertion Loss........................................................................................................................6-7
Delay.......................................................................................................................................6-7
Length ....................................................................................................................................6-7
Chapter 7 Fast Ethernet Network Requirements
100BASE-TX..................................................................................................................................7-1
Cable Type .............................................................................................................................7-1
Insertion Loss (Attenuation)...............................................................................................7-2
Impedance .............................................................................................................................7-2
Jitter ........................................................................................................................................7-2
Delay.......................................................................................................................................7-3
Crosstalk ................................................................................................................................ 7-3
Noise.......................................................................................................................................7-3
Other Considerations...........................................................................................................7-3
100BASE-FX (Multimode) .......................................................................................................... 7-4
Cable Type .............................................................................................................................7-4
Attenuation............................................................................................................................7-4
Insertion Loss........................................................................................................................7-4
Delay.......................................................................................................................................7-5
Length ....................................................................................................................................7-5
Hybrid Installations ....................................................................................................................7-5
Repeater Classes ................................................................................................................... 7-6
Buffered Uplinks...................................................................................................................7-7
v
Chapter 8 Full-Duplex Fast Ethernet Network Requirements
100BASE-TX..................................................................................................................................8-1
Cable Type .............................................................................................................................8-1
Insertion Loss (Attenuation) ...............................................................................................8-2
Impedance .............................................................................................................................8-2
Jitter.........................................................................................................................................8-2
Crosstalk ................................................................................................................................8-2
Noise.......................................................................................................................................8-3
Other Considerations...........................................................................................................8-3
Length.....................................................................................................................................8-4
100BASE-FX (Multimode) ..........................................................................................................8-5
Cable Type .............................................................................................................................8-5
Attenuation............................................................................................................................8-5
Insertion Loss ........................................................................................................................8-5
Delay.......................................................................................................................................8-5
Length.....................................................................................................................................8-6
Chapter 9 Token Ring Media
Cabling Types ...............................................................................................................................9-1
Shielded Twisted Pair (STP) ................................................................................................9-1
Unshielded Twisted Pair (UTP) ..........................................................................................9-5
Fiber Optics............................................................................................................................9-8
Connector Types.........................................................................................................................9-10
STP ........................................................................................................................................9-10
Unshielded Twisted Pair Cable ........................................................................................9-15
Fiber Optics..........................................................................................................................9-17
Chapter 10 Token Ring Network Requirements
IEEE 802.5 Shielded Twisted Pair ............................................................................................10-1
Cable Type ...........................................................................................................................10-1
Attenuation..........................................................................................................................10-2
Impedance ...........................................................................................................................10-2
Link Length .........................................................................................................................10-3
Trunk Cable Length............................................................................................................10-4
IEEE 802.5 Unshielded Twisted Pair .......................................................................................10-5
Cable Type ...........................................................................................................................10-5
Attenuation..........................................................................................................................10-5
Impedance ...........................................................................................................................10-6
Crosstalk ..............................................................................................................................10-6
Link Length .........................................................................................................................10-6
Trunk Cable Length............................................................................................................10-7
vi
IEEE 802.5j (Multimode Fiber Optics) ....................................................................................10-8
Cable Type ...........................................................................................................................10-8
Attenuation..........................................................................................................................10-9
Link Length ......................................................................................................................... 10-9
Trunk Cable Length............................................................................................................10-9
IEEE 802.5j Single Mode Fiber Optics................................................................................... 10-10
Cable Type .........................................................................................................................10-10
Attenuation........................................................................................................................10-10
Link Length ....................................................................................................................... 10-10
Trunk Cable Length..........................................................................................................10-10
Chapter 11 FDDI Media
Cabling Types ............................................................................................................................. 11-1
Unshielded Twisted Pair (UTP)........................................................................................ 11-1
Shielded Twisted Pair (STP).............................................................................................. 11-5
STP Cable Quality ..............................................................................................................11-7
Fiber Optics .........................................................................................................................11-8
Connector Types ...................................................................................................................... 11-11
UTP..................................................................................................................................... 11-11
STP...................................................................................................................................... 11-12
Fiber Optics .......................................................................................................................11-13
Chapter 12 FDDI Network Requirements
MMF-PMD.................................................................................................................................. 12-1
Cable Type ...........................................................................................................................12-1
Attenuation..........................................................................................................................12-1
Length ..................................................................................................................................12-2
Emitted Power ....................................................................................................................12-2
SMF-PMD ...................................................................................................................................12-2
Cable Type ...........................................................................................................................12-2
Attenuation..........................................................................................................................12-2
Length ..................................................................................................................................12-3
Emitted Power ....................................................................................................................12-3
LCF-PMD....................................................................................................................................12-3
Cable Type ...........................................................................................................................12-3
Attenuation..........................................................................................................................12-3
Length ..................................................................................................................................12-4
Emitted Power ....................................................................................................................12-4
TP -PMD (UTP)..........................................................................................................................12-4
Cable Type ...........................................................................................................................12-4
Attenuation..........................................................................................................................12-4
Length ..................................................................................................................................12-5
TP-PMD (STP)............................................................................................................................12-5
Cable Type ...........................................................................................................................12-5
Attenuation..........................................................................................................................12-5
Length ..................................................................................................................................12-5
vii
Chapter 13 Cabling Devices
Hardware Mounting..................................................................................................................13-2
Relay Rack ...........................................................................................................................13-2
Enclosed Equipment Cabinet............................................................................................13-3
Cable Termination......................................................................................................................13-4
Patch Panel ..........................................................................................................................13-4
Harmonica ...........................................................................................................................13-5
Punchdown Block...............................................................................................................13-6
Distribution Box..................................................................................................................13-7
Wallplate ..............................................................................................................................13-8
Surface Mount Box .............................................................................................................13-9
Facility Cable Management......................................................................................................13-9
Conduit ................................................................................................................................13-9
D-Rings...............................................................................................................................13-10
J-Hooks...............................................................................................................................13-11
Strain-Relief Bracket.........................................................................................................13-11
Innerduct............................................................................................................................13-12
Latching Duct....................................................................................................................13-12
Raceway .............................................................................................................................13-13
Labeling Tape ....................................................................................................................13-13
Ty-Wraps and Adhesive Anchors...................................................................................13-14
Chapter 14 Connecting and Terminating
Ethernet .......................................................................................................................................14-1
DB15......................................................................................................................................14-1
RJ45.......................................................................................................................................14-3
RJ21.......................................................................................................................................14-4
BNC ......................................................................................................................................14-5
N-Type..................................................................................................................................14-7
ST Connector .......................................................................................................................14-7
Token Ring ..................................................................................................................................14-9
DB9........................................................................................................................................14-9
RJ45.....................................................................................................................................14-10
Token Ring MIC ................................................................................................................14-12
ST Connector .....................................................................................................................14-13
FDDI...........................................................................................................................................14-14
RJ45.....................................................................................................................................14-14
FDDI MIC ..........................................................................................................................14-16
SC Connector.....................................................................................................................14-18
Appendix A Charts and Tables
Ethernet ........................................................................................................................................A-1
Token Ring ...................................................................................................................................A-4
FDDI..............................................................................................................................................A-6
viii
Introduction
Using This Guide
The Cabletron Systems Cabling Guide is intended to provide much of the
information necessary to allow Network Managers to plan facility network
cabling and to ensure that the cabling is usable by the networking devices that
will populate the cabling.
Chapter 1
This Cabling Guide also provides instructions that may be helpful for connecting
Cabletron Systems networking devices to an existing facility cabling
infrastructure.
Document Organization
This guide begins with an overview of the important aspects of cabling and
cables. The information presented in the initial sections is essential to a complete
understanding of the material that is presented in later sections. Following the
introductory material, detailed examinations of the standard media and
connectors used for Ethernet, Token Ring, and Fiber Distributed Data Interface
(FDDI) networks are presented. The closing sections of the document describe
some common installation and cable management devices, and explain some
methods for testing cables and planning installations.
The remainder of this guide contains charts and tables which supply much of the
information that the cable system planning process requires, and an extensive
glossary of the terms used within this guide and other Cabletron Systems
publications.
1-1
Introduction
The following summarizes the organization of this manual:
Chapter 1, Introduction , discusses the use and contents of this guide.
Chapter 2, Cabling Terms , defines and explains some of the terminology
used throughout this document to describe aspects and components of
cabling and installation planning.
Chapter 3, Relevant Specifications , details some relevant specifications and
standards that apply to the installation of facility network cabling.
Chapter 4, Ethernet Media , identifies and discusses several networking
cables and their characteristics when used in Ethernet and Fast Ethernet
networking environments. The chapter examines the physical characteristics
and requirements of both physical cabling and the connectors and ports used
with the cabling.
Chapter 5, Ethernet Network Requirements , provides a series of test
envelopes and installation requirements that Ethernet cabling must meet in
order to conform to the Ethernet standard.
Chapter 6, Full-Duplex Ethernet Network Requirements , supplies the test
characteristics and network limitations of Ethernet networks intended to
operate in full-duplex mode.
Chapter 7, Fast Ethernet Network Requirements , deals with the cable
characteristics and requirements of the Fast Ethernet networking technology,
including 100BASE-TX and 100BASE-FX.
Chapter 8, Full-Duplex Fast Ethernet Network Requirements , Provides
specific information related to the requirements of full-duplex Fast Ethernet
network cabling.
Chapter 9, Token Ring Media , identifies and details the cables and
connectors that may be used in Token Ring network environments.
Chapter 10, Token Ring Network Requirements , lists the required
performance and test characteristics of Token Ring cabling.
Chapter 11, FDDI Media , lists and describes the various cabling types that
may be used with Fiber Distributed Data Interface (FDDI) networks.
Chapter 12, FDDI Network Requirements , lists the required test
characteristics and accepted maximums of cabling used in FDDI network
installations.
Chapter 13, Cabling Devices , provides a list of several useful tools and
accessories that can aid in the installation, management, and control of
installed cabling in a facility.
Chapter 14, Connecting and Terminating , describes the procedures involved
in connecting and disconnecting the standard connectors of each network
technology treated in Chapters 4, 9, and 11.
1-2 Document Organization
Appendix A, Charts and Tables , provides the information contained in the
network requirements chapters of this document in a simplified table form.
Tables of test requirements and acceptable levels are provided for all media
discussed in this document.
Following the appendix, the Cabletron Systems Glossary of Terms may be found.
Document Conventions
Warnings and Notifications
Introduction
Formats
NOTE
TIP
CAUTION
References to chapters or sections within this document are printed in boldface
type.
References to other Cabletron Systems publications or documents are printed in
italic type.
Note symbol. Calls the reader’s attention to any item of
information that may be of special importance.
Tip symbol. Used to convey helpful hints concerning
procedures or actions that would assist the operator in
performing the task in a more timely manner in the future.
Caution symbol. Used to caution against an action that could
result in damage to equipment or poor equipment performance.
!
Warning symbol. Used to warn against an action that could
result in personal injury or death and equipment damage.
Document Conventions 1-3
Introduction
Additional Assistance
The planning and installation of facility cabling for network operation is a
complex and highly specialized process. Due to the different nature of each and
every cabling installation and the special problems and concerns raised by any
facility, there may be aspects of installation planning that are not covered in this
guide.
If you have questions or concerns about your cabling design, or if you require
installation personnel to perform the actual installation process, Cabletron
Systems maintains a staff of network design personnel and a sizable team of
highly-trained cabling and hardware installation technicians. The services of the
Networking Services group are available to customers at any time. If you are
interested in obtaining design assistance or a network installation plan from the
Networking Services group, contact your Cabletron Systems Sales
Representative.
In addition to the availability of Networking Services, the Cabletron Systems
Technical Support department is available to answer customer questions
regarding existing Cabletron Systems networks or planned expansion issues.
Contact Cabletron Systems at (603) 335-9400 to reach the Technical Support
department with any specific product-related questions you may have.
Related Documentation
The following publications may be of assistance to you in the design process.
Several of these documents present information supplied in this Cabling Guide in
greater or lesser detail than they are presented here.
• Cabletron Systems Networking Guide - MMAC-FNB Solutions
• Cabletron Systems Ethernet Technology Guide
• Cabletron Systems Token Ring Technology Guide
• Cabletron Systems FDDI Technology Guide
• EIA/TIA 568 Specification
• IEEE 802.3 Specifications
• IEEE 802.5 Specifications
• ANSI X3T9.5 Specification
1-4 Additional Assistance
Chapter 2
Cabling Terms
This chapter identifies and defines several terms that are used throughout the text of this manual.
Physical Components
The following terms and definitions deal with the physical makeup of cabling
used in Local Area Networks.
Media
Media refers to a type or family of cables. When the term media is used, it
indicates a type of cabling, rather than a specific cable. A reference to “fiber optic
media” deals with the characteristics of all fiber optic cable types, such as single
or multimode fiber optics.
Cable
The term cable, as used in this document, indicates either a specific type of
transmission media (i.e., multimode fiber optic cable) or indicates a physical
section of that media (i.e., “the installed cable must be no longer than 200 m”).
Facility Cabling
Facility cabling, sometimes referred to as building cable or horizontal cable, is the
network cabling that is installed in a building or office. It only includes the actual
wires that are placed within the walls, conduits, or specific cable channels of the
building. The majority of cabling used in a network installation is facility cabling.
2-1
Cabling Terms
Jumper Cabling
Run
Jumper cabling is a term that identifies short, inexpensive cables that are used to
make connections between nearby cabling devices. Typically, workstations and
network devices are connected to the facility cabling of a site with jumper cables.
A “run” of cabling is a single end-to-end cable path in a networked facility. The
cable run typically begins at a network device such as a hub or bridge and ends at
a workstation or other end node. The cable run, if calculated, must include all
areas on the cable to which signals will travel. On point-to-point media, such as
UTP or fiber optics, this will be the same as the measure of cabling between
stations. In a shared media environment, however, the measure of a run must
include the total length of the shared cable being used, regardless of the distance
between stations on that cable.
Wire
Core
A cable run includes the facility cabling, jumper cabling, and any passive cable
management devices, such as wallplates, patch panels, and punchdown blocks,
between the two devices. When a specific type of cabling is referred to when
identifying a cable run, the term refers only to the total length of that type of cable
in the installation.
As an example, if a thick coaxial cable run is referred to in an installation
description, it is concerned with the total length of coaxial cable and does not
include the AUI cables used to connect stations to transceivers on the thick coaxial
cable. If a UTP cable run is referred to, it includes only the jumper cables, patch
panels, wallplates, and facility cabling between the devices in question.
The wire terms listed below deal with the components that make up a physical
cable.
The core of a wire is that portion of the wire upon which the electrical (or light, in
the case of fiber optics) signals of network communications travel. In all cases, the
term core refers to the transmissive center of the cable or wire in question. The
term core is most often used when referring to a cable that has a single
transmission path. Cables with multiple transmission paths cannot have an
overall core.
2-2 Physical Components
Strand
Insulator
Shield
Cabling Terms
A strand is a metal or glass (in the case of fiber optics) transmission media that is
typically surrounded by an insulator. Strands in metallic cables may be made up
of either solid lengths of relatively thick wire (solid core) or a bundle of much
thinner wires that contact one another throughout the wire (stranded).
An insulator is a layer of non-conductive material that protects the core or strands
of a cable from both physical damage and from the effects of other strands within
a multistranded cable. Insulator also protects the strands or core from the effects
of external electrical noise to a small extent.
A shield is a layer of metal foil or braided screen that protects the core or strands
of the cable from interference from outside electrical influences. The shield is
wrapped around the core, and is separated from the core by a layer of insulator.
Gauge
Connector
The gauge of a wire is an indication of its thickness. Gauge is typically measured
in American Wire Gauge (AWG). The lower the AWG number of a strand or core,
the thicker it is. The gauge of a wire has an affect on the resistance it presents to
electrical signals attempting to travel through it. In general, lower-gauge (thicker)
strands allow network communications to travel through them more readily than
strands with a higher gauge.
A connector is a metal, plastic, or composite assembly that is used to simplify the
connection of separate lengths of cable or to connect cables to devices. Connectors
are only found on cables (ports are located on devices). The terms that follow
define important parts of connectors.
Physical Components 2-3
Cabling Terms
Housing (Shell)
Pin
The basis of the connector is its housing. A housing is the metal or plastic parts
that make up the shape of the connector and determine its characteristics and
what ports or other connectors it may be attached to. The purpose of the housing
is to separate and organize any strands in the cable being connected and arrange
them in a standard fashion for connection to a port or other connector.
If a housing can be assembled and disassembled easily, or is made up of several
separate sections, it may be called a shell.
A pin is an exposed metal prong or wire that is either inserted into a channel or
allowed to touch a contact. In this fashion, the pin creates a path for network
signals to flow from the connector to the port or device it is connected to.
Pins may be fully exposed, for insertion into a channel, or partially exposed, for
connection to a contact. Fully exposed pins will protrude from a housing or
insulator. Partially exposed pins are encased on two or three sides by the
construction material of the connector housing. An example of a partially exposed
pin is that used in the RJ45 modular connector.
Contact
Channel
A contact refers to a location where one electrical transmission carrier meets
another and creates a link through which electrical signals may be passed.
Contacts, when referred to as physical parts of a connector or port, are usually
flat, exposed metal surfaces.
A channel is a hollow cylinder, usually metal, that receives a fully exposed pin.
The pin is inserted into the channel, where an electrical contact is made.
The cabling term “channel” should not be confused with the networking term
“channel,” which refers to a logical path or group of paths of transmission and
reception for network signals.
2-4 Physical Components
Gender
Cabling Terms
The gender of a connector refers to the organization of the pins, contacts, or
channels of the connector. Connectors may be identified as male, female,
hermaphroditic, or genderless. The most common types of connectors in
networking are male and female.
A male connector is one that is inserted into a recessed or hollow port. In the case
of some connectors, the determination of male gender is based upon whether the
connector makes its networking connection through a pin or a channel.
Connectors with pins are considered male.
Female connectors are those that are constructed to accept a male connector.
Female connectors typically provide channels into which the pins of male
connectors are inserted. A readily available example of male and female
connectors is the standard electrical extension cord. The extension cord has a male
end, the prongs that are placed in the wall outlet, and a female end, the slots on
the opposite end of the cable.
Connections in any gendered cable systems must be made between one male
connector and one female connector. The connectors themselves will not allow
male/male or female/female connections.
Keyed
Threaded
Locking
Some connectors are genderless or hermaphroditic. These are connectors that
have aspects of both male and female connector types. They may be connected to
any other port or connector. The Token Ring MIC connector is perhaps the most
common genderless connector in networking.
A keyed connector is one that has a housing specifically designed to be connected
to a port in a particular orientation. The keyed connector is shaped in such a way
that it may only be inserted into the port or connector so that the pins or channels
of the housing match up properly.
Threaded connectors are designed to be secured to other threaded connectors or
ports. They are designed to be screwed together. The threads hold the connectors
in place.
A locking connector is one that snaps into place. Locking connectors are usually
keyed, and are often gendered. The locking action holds the connector firmly in
place and makes the connection resistant to disconnection due to strain or
movement. Locking may be accomplished by a spring clip mechanism or by the
use of key pins and locking channels.
Physical Components 2-5
Cabling Terms
Port
A port is a set of pins or channels on a networking or cabling device that are
arranged to accept a connector. Ports are constructed much like connectors, and
will only accept the connector type they are specifically designed for. Ports may
be keyed, gendered, or locking, in the same fashion as connectors.
Jack
A jack is a term that is usually synonymous with port, and indicates a port
location. Typically, the term refers to ports located on wallplates or other passive
cabling devices.
Test Characteristics
The following section deals with the various important specifications and testing
information related to the cabling and connectors used in LAN environments.
Impedance
Crosstalk
Noise
Impedance is the resistance that a conductive cable offers to the transmission of
current. Impedance is measured in ohms (Ω). Cables with high Impedance values
are highly resistant to the transmission of electrical signals. Some network
operation specifications and network devices require the use of cabling with
specific impedance levels and will not work properly with cabling having
significantly higher or lower values.
Crosstalk is electrical interference between wires in a multi-stranded cable, such
as Unshielded Twisted Pair (UTP) cabling. Crosstalk occurs when a cable strand
or group of strands absorb signals from other wires that they are adjacent to.
Crosstalk can be caused by a break in the insulation or shielding that separates
wires from one another in a bundle.
In regards to network cabling, the term noise refers to electrical noise, electrical
signals that are spontaneously introduced onto a cable due to that cables
proximity to noise sources. Typical sources of electrical noise include lighting
fixtures, electric motors, and transformers.
2-6 Test Characteristics
Delay
Attenuation
Cabling Terms
The term delay, when applied to network cabling, typically refers to the
propagation delay of the segment or network. As signals in both electrically
conductive cables and fiber optic cables travel through the transmission media at
a fraction of the speed of light, there is an appreciable delay between the
transmission of a signal on one end of a cable and the reception of the same signal
on the other end. Network delay is typically measured in microseconds (µs). One
microsecond is equal to 1/1,000,000 of a second.
Attenuation is the reduction of signal strength in a cable as a result of absorption
or dispersion of the electrical or optical impulse traveling through the cable. The
effect of attenuation is a gradual decrease in the power or clarity of a signal after it
traverses a length of cabling. The measure of the attenuation of a cable is
expressed in decibels (dB).
There are two different measures of attenuation that are important from a
networking point of view. The first is the attenuation characteristics of a cable.
These are estimates of the expected attenuation that a signal will suffer for
passing through a given length of the cable. Expected attenuation values are
expressed in dB/m, dB/km, or dB/ft.
The second measure of attenuation is that which is determined by testing a length
of cable to determine its total attenuation. Total attenuation takes into account all
components of the cable run and is expressed as a total measure of signal loss in
decibels from one end of the cable to the other.
Test Characteristics 2-7
Cabling Terms
2-8 Test Characteristics
Chapter 3
Relevant Specifications
This chapter presents and examines a number of networking specifications and how they are related
to planning and installing network cabling.
Just as there are specifications that deal with the tested aspects of installed cabling
and their fitness for use with a particular networking technology, there are also
standards that deal with the construction of cables and the methods by which
they may be installed. These higher-level cabling standards involve such things as
the pairing and insulating of cables within a multi-wire cable, the labeling of cable
jackets, and the allowable proximity of cables of certain types to other cables or
electrical equipment.
EIA/TIA
These higher-level specifications are out of the purview of this Cabling Guide,
and are not covered in detail within this document. Some of the aspects treated by
the higher-level specifications are discussed in the sections which follow, as they
impact or affect the use or selection of cabling materials in certain facilities or for
use with individual networking standards.
The EIA/TIA specifications deal with the recommended methods and practices
for constructing, installing, and terminating wiring. There are several different
EIA/TIA specifications which cover different aspects of wiring. EIA/TIA
specification number 568 is the one that network installers are most commonly
interested in, as it deals with the installation of networking and telephony and
networking cable.
The construction specifications of the EIA/TIA specification are important only
when selecting a specific type of cable. The EIA/TIA construction specification
used in the manufacture of that cable determines the construction and tested
characteristics of the cable, the organization and quality of its components, and
what applications it is suited for.
3-1
Relevant Specifications
The installation procedures of the EIA/TIA help to ensure that care is taken to
avoid cabling situations that are possibly hazardous or which can result in
degradation of the operating quality of the installed cable.
The EIA/TIA 568 specification details the minimum distance that cables may be
located away from sources of electrical noise, what types of power cables or other
telephony cabling the cables being installed may be next to, how the connectors
must be installed, and other aspects which affect the overall usability of the cable
for a particular purpose.
Full copies of the EIA/TIA 568 specification may be obtained from a technical
document seller or ordered directly from the Electronics Industries
Association/Telecommunications Industry Association.
Universal Service Order Code (USOC)
The USOC specification is similar to many EIA/TIA specifications, including
EIA/TIA 568. The USOC specification describes, among other things, the
construction and installation characteristics of a type of twisted pair cable. The
USOC specification deals with the same aspects of the installation process as the
EIA/TIA specifications, but provides slightly different guidelines.
Originally, the specification was drafted by the Bell System, and copies of the
USOC specification may be obtained from technical booksellers or those Regional
Bell Operating Companies (RBOCs) which provide specifications to customers.
National Electrical Code (NEC)
The National Electrical Code or NEC is an overall specification to which all
facility wiring of any kind in the United States of America must be held. As the
NEC is a higher-level standard than either the EIA/TIA or USOC specifications,
the two lower-level specifications are designed to be automatically in accordance
with the NEC.
3-2 Universal Service Order Code (USOC)
Chapter 4
Ethernet Media
This chapter examines the physical characteristics and requirements of both physical cabling and the
connectors and ports used with the cabling in Ethernet , Full-Duplex Ethernet, and Fast Ethernet
environments.
Cabling T ypes
Attachment Unit Interface (AUI)
Attachment Unit Interface cable (referred to hereafter as AUI cable) is a shielded,
multistranded cable that is used to connect Ethernet network devices to Ethernet
transceivers. AUI cable should be used for no other purpose. AUI cable is
available in two basic types: standard AUI and office AUI.
AUI cable is made up of four individually shielded pairs of wire surrounded by
an overall cable shielding sheath. The doubled shielding makes AUI cable more
resistant to electrical signal interference than other, lighter cables, but increases
the signal attenuation suffered over long distances.
AUI cables are connected to other devices through DB15 connectors. The
connectors of an AUI cable run from Male to Female at all times. Any transceiver
cable that uses a Male/Male or Female/Female configuration is a non-standard
cable, and should be avoided.
4-1
Ethernet Media
YES
Standard
NO NO
1845n01
Figure 4-1. AUI Cable Configurations
The reason for the configuration of AUI cables as Male to Female only is due to
their intended use. AUI cables are designed to attach transceivers to workstations
or other active network equipment. Transceivers require power to operate, and
that power is supplied either by an external power supply or by a pair of wires
dedicated to power in the cable. A Male/Male or Female/Female AUI cable does
not correctly supply power and grounding to the transceiver. If you use a
Female/Female AUI cable between two transceiver devices, both transceivers will
try to draw power from each other. Neither is capable of providing this power.
Therefore, this configuration will not function. Likewise, two AUI device ports
should never be directly attached without using transceivers.
If you find yourself in need of a gender changer to connect a
NOTE
device with AUI cable, you are doing something wrong.
The gauge of the internal wires that make up the cable determines the thickness
and relative flexibility of the AUI cable. Standard AUI cable (containing pairs of
AWG 20 or 22 wire) is capable of reaching a maximum distance of 50 meters
between transceivers and the network device, but is thick, (0.420 inch) and
somewhat inflexible.
Standard AUI cables, due to their bulk, are typically used in environments that
require the 50 meter distances that standard AUI cables can provide. In situations
where the workstations or networking equipment are close to the transceivers
they are to be connected to, Office AUI cable, being more easily managed and
more flexible, is often used.
4-2 Cabling Types
Office
Coaxial Cable
Ethernet Media
Office AUI cable is a thinner cable that is more convenient to use on many
environments than standard AUI. This lighter-gauge AUI cable is made up of four
pairs of AWG 28 wire, which is thinner (at 0.26 inch) and much more easily flexed,
but can only be run to a maximum distance of 16.5 meters.
Office AUI cable is intended to be used in places where standard AUI cable would
be cumbersome and inflexible. Typically, office AUI is used in locations where a
large number of workstations are concentrated in a single area.
Coaxial cable is a cabling type where two or more separate materials share a
common central axis. While several types of networking cables could be
identified as having coaxial components or constructions, there are only two cable
types that can support network operation using only one strand of cabling with a
shared axis. These are commonly accepted as the coaxial cables, and are divided
into two main categories: thick and thin coaxial cable.
Thick Coaxial Cable
Thick coaxial cable (also known as thick Ethernet cable, “thicknet,” or 10BASE5
cable), is a cable constructed with a single solid core, which carries the network
signals, and a series of layers of shielding and insulator material. The shielding of
thick coaxial cable consists of four stages. The outermost shield is a braided metal
screen. The second stage shield, working inward, is usually a metal foil, but in
some brands of coaxial cable may be made up of a second screen. The third stage
consists of a second braided shield followed by the fourth stage, a second foil
shield. The various shields are separated by non-conductive insulator materials.
Foil Shield
Solid Core
Insulator
Braided Shield
Outer Jacket
1845n02
Figure 4-2. Thick Coaxial Cable Diagram
Cabling Types 4-3
Ethernet Media
Thick coaxial cable is a media used exclusively in Ethernet installations,
commonly as a backbone media. Transceivers are connected to the cable at
specified distances from one another, and standard transceiver cables connect
these transceivers to the network devices.
Due to the extensive shielding, thick coaxial cable is highly resistant to electrical
interference by outside sources such as lighting, machinery, etc. Because of the
bulkiness (typically 0.405 inch in diameter or thicker) and limited flexibility of the
cable, thick coaxial cable is primarily used as a backbone media and is placed in
cable runways or laid above ceiling tiles to keep it out of the way.
Thick coaxial cable is designed to be accessed as a shared media. Multiple
transceivers can be attached to the thick coaxial cable at multiple points on the
cable itself. A properly installed length of thick coaxial cable can support up to
100 transceivers.
Annular Rings
Coaxial Cable
Thin Coaxial Cable
N-Type
Connector
2.5 m
(10BASE5)
1845n03
Figure 4-3. Annular Rings
Multiple transceivers on a thick coaxial cable must be spaced at least 2.5 meters
from any neighboring transceivers or terminators. Thick coaxial cable is often
bright yellow or orange in color. The outer jacket will frequently be marked with
annular rings, dark red or black sections of jacketing that are spaced 2.5 meters
from one another. These annular rings are a useful guide for ensuring that
terminators and transceivers are spaced not less than 2.5 m from one another.
Thin coaxial cable (also known as thin Ethernet cable, “thinnet,” “cheapernet,”
RG-58 A/U, BNC or 10BASE2 cable) is a less shielded, and thus less expensive,
type of coaxial cabling. Also used exclusively for Ethernet networks, thin coaxial
cable is smaller, lighter, and more flexible than thick coaxial cable. The cable itself
resembles (but is not
identical to) television coaxial cable.
Thin coaxial cable is made up of a single outer copper shield that may be braided
or foil, a layer beneath that of non-conductive dielectric material, and a stranded
center conductor. This shielding makes thin coaxial cable resistant to
electromagnetic interference as the shielding of thick coaxial cable does, but does
not provide the same extent of protection. Thin coaxial cable, due to its less
extensive shielding capacity, can be run to a maximum length of 185 meters
(606.7 ft).
4-4 Cabling Types
Building Network Coax (BNC) connectors crimp onto a properly prepared cable
end with a crimping tool. To prevent signal reflection on the cable, 50 Ohm
terminators are used on unconnected cable ends.
As with thick coaxial cable, thin coaxial cable allows multiple devices to connect
to a single cable. Up to 30 transceivers may be connected to a single length of thin
coaxial cable, spaced a minimum of 0.5 meter from one another. This minimum
spacing requirement keeps the signals from one transceiver from interfering with
the operation of others. The annular rings on the thin coaxial cable are placed 0.5
meter apart, and are a useful guide to transceiver placement.
Unshielded Twisted Pair (UTP)
Unshielded Twisted Pair cabling (referred to here as UTP, but also may be termed
copper wire, 10BASE-T wire, Category 3, 4, or 5 Ethernet wire, telephone cable, or
twisted pair without shielded or unshielded qualifier) is commonly made up of
two, four, or 25 pairs of 22, 24, or 26 AWG unshielded copper solid or stranded
wires. These pairs of wires are twisted together throughout the length of the
cable, and are broken up into transmit and receive pairs. In each pair, one wire
carries the normal Ethernet transmission, while its associated wire carries a copy
of the transmission that has been inverted.
Ethernet Media
Tx+
Tx-
RxRx+
1845n04
Figure 4-4. UTP Cable Pair Association
The twisting of associated pairs helps to reduce the interference of the other
strands of wire throughout the cable. This is due to the method of transmission
used with twisted pair transmissions.
In any transceiver or Network Interface Card (NIC), the network protocol signals
to be transmitted are in the form of changes of electrical state. The means by
which the ones and zeroes of network communications are turned into these
signals is called encoding. In a twisted pair environment, once a transceiver has
been given an encoded signal to transmit, it will copy the signal and invert the
polarity of that signal (see Figure 4-5). The result of this inverted signal is a mirror
opposite of the original signal.
Cabling Types 4-5
Ethernet Media
Both the original and the inverted signal are then transmitted, the original signal
over the TX+ wire, the inverted signal over the TX - wire. As these wires are the
same length and of the same construction, the signal travels (propagates) at the
same rate through the cable. Since the pairs are twisted together, any outside
electrical interference that affects one member of the pair will have the same effect
on the other member of that pair.
The transmissions travel through the cable, eventually reaching a destination
transceiver. At this location, both signals are read in. The original signal is
unchanged, but the signal that had previously been inverted is reverted to the
original state. When this is done, it returns the encoded transmission to its
original state, but reverses the polarity of any signal interference that the encoded
transmission may have suffered.
Once the inverted transmission has been returned to the normal encoded state,
the transceiver adds the two signals together. As the encoded transmissions are
now identical, there is no change to the data content. Line noise spikes, however,
are combined with noise spikes of their exact opposite polarity, causing them to
cancel one another out.
Original Signal
Normal
Transmission
Inverted
Transmission
Induced
Noise Spike
Reversion of Inverted
Transmission
Noise spikes
cancel out
Resulting Signal
1845n05
Figure 4-5. UTP Signal Equalization
The UTP cable used in network installations is the same type of cable used in the
installation of telephone lines within buildings. UTP cabling is differentiated by
the quality category of the cable itself, which is an indicator of the type and
quality of wire used and the number of times the wires are twisted around each
other per foot. The categories range from Category 1 to Category 5, with Category
5 cabling being of the highest quality.
The wires that make up a length of UTP cable are numbered and color coded.
These color codes allow the installer of the networking cable to determine which
wires are connected to the pins of the RJ45 ports or patch panels. The numbering
of the wires in EIA/TIA standard cables is based on the color of the insulating
jacket that surrounds the core of each wire.
4-6 Cabling Types
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