Structured Cabling Systems, Standards, and Codes 889
Servicing the Work Area
Patching is done when connectivity changes are needed often or are foreseen. It is
much easier to patch cable from the work area outlet to a new position in the TR than
it is to remove terminated wires from connected hardware and reterminate them to
another circuit. Patch cords also are used to connect networking equipment to the
cross-connects in a TR. Patch cords are limited by the TIA/EIA-568-B.1 standard to
5m (16.4 ft.).
A uniform wiring plan must be used throughout a patch panel system. All jacks and
patch panels should be wired using the same wiring plan. If the T568A wiring plan is
used for the information outlets or jacks, T568A patch panels should be used. The
same is true for the T568B wiring plan.
Patch panels can be for unshielded twisted-pair (UTP), shielded twisted-pair (STP), or
fiber-optic connections. The most common patch panels are for UTP. These patch pan-
els use RJ-45 jacks; patch cords with RJ-45 plugs connect to these ports.
In most facilities, there is no provision to keep authorized maintenance personnel from
installing unauthorized patches or installing an unauthorized hub into a circuit. There
is an emerging family of automated patch panels, however, which can provide exten-
sive network monitoring in addition to simplifying the provisioning of moves, adds,
and changes. These patch panels normally provide an indicator lamp over any patch
cord that need to be removed, and then once the cord is released, provide a second
light over the jack to which they should be re-affixed. In this way, the system can auto-
matically guide a relatively unskilled employee through moves, adds, and changes.
The same mechanism that detects when the operator has moved a given jack works
also to detect when a jack has been pulled. An unauthorized resetting of a patch can
trigger an event in the system log, and if need be, trigger an alarm. For example, if a
half-dozen wires to the work area suddenly show up as being open, and it is 2:30 A.M.,
this is an event worth looking into, because theft may be occurring.
Types of Patch Cables
Patch cables (see Figure A-7) come in a variety of wiring schemes. The most common,
the straight-through cable, has the same wiring scheme on both ends of the cable. In

other words, pin 1 on one end is connected to pin 1 on the other end. Pin 2 on one end
corresponds to pin 2 on the other, and so on. These types of cables connect PCs to a
network hub.

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890 Appendix A: Structured Cabling
Figure A-7 UTP Patch Cable
When connecting a communications device to a network hub, a crossover cable usually
is used. Crossover cables use the T568A wiring plan on one end and T568B on the other.
Cable Management
Cable-management devices are used for routing cables and providing a neat and orderly
path for the cables and to assure minimum bend radius is maintained. Cable manage-
ment also eases cable additions and modification to the wiring system. Many options
for cable management exist in the TR. Cable baskets can be used when an easy, light-
weight installation is needed. Ladder racks often are used when heavy loads of bundled
cable need to be supported. Different types of conduits can be used to run cable inside
walls, ceilings, and floors, or when they need to be shielded from external conditions.
Cable management systems are used vertically and horizontally on telecommunica-
tions racks to distribute cable in a neat and orderly fashion (see Figure A-8).
MC, IC, and HC
Most networks have more than one TR for various reasons. First of all, a medium or
large network usually is spread over many floors or buildings. A TR is needed for each
floor of each building (see Figure A-9). Second, media can carry a signal only so far
before the signal starts to degrade or attenuate. Therefore, TRs are located at defined
distances throughout the LAN to provide interconnects and cross-connects to hubs
and switches to assure desired network performance. These TRs house equipment,
such as repeaters, hubs, bridges, or switches, that are needed to regenerate the signals.
Lab Activity Examination of Termination Types
In this lab, you review the T568A, T568B, and RJ-45 USOC wiring standards,
and you learn to terminate the ends of a Category 5e cable.


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Structured Cabling Systems, Standards, and Codes 891
Figure A-8 Panduit Rack-Mounted Vertical and Horizontal Cable Management System
Figure A-9 MC, HC, and IC Planning
MC
demarc

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892 Appendix A: Structured Cabling
Not all TRs are equal. The primary TR, called the main cross-connect (MC), is the
center of the network. This is where all the wiring originates and where most of the
equipment is housed. The intermediate cross-connect (IC) is connected to the MC and
can house the equipment for a building on a campus. The horizontal cross-connect
(HC) provides the cross-connect between the backbone and horizontal cables on a
single floor of a building.
Main Cross-Connect
The MC is the main concentration point of an entire building or campus. In effect,
the MC is the primary TR. It is the room that controls the rest of the TRs (the ICs and
HCs) in a building or campus. In some networks, it is the place where the inside cable
plant meets the outside world’s connectivity (the demarc).
All ICs or HCs are connected to the MC in a star topology. Backbone cabling, or ver-
tical cabling, is used to connect those ICs and HCs located on other floors. Where the
entire network is confined to a single multistory building, the MC usually is located on
one of the middle floors of the building, even though the demarc might be located in
an entrance facility on the first floor or in the basement.
For networks that comprise multiple buildings, one building typically houses the MC.
Each individual building typically has its own version of the MC, called the intermediate
cross-connect (IC), which connects all the HCs within the building. The IC allows the
extension of backbone cabling from the MC to each HC because this interconnection

point does not degrade the communication signals. Only one MC can exist for the
entire structured cabling installation. The MC feeds the ICs, and each IC feeds multiple
HCs. There can be only one IC between the MC and any HC.
The backbone cabling (red lines in the figure) runs from the MC to each of the ICs.
The ICs are located in each of the campus buildings, and the HCs serve work areas.
Horizontal cabling, running from the HCs to the work areas, is represented by the
black lines.
Horizontal Cross-Connect
The horizontal cross-connect (HC) is the TR closest to the work areas. Like all copper
cross-connects, the HC is typically a patch panel or punch-down block, and possibly
networking devices such as repeaters, hubs, or switches. It can be a rack mounted in a
room or in a cabinet. Because a typical horizontal cable system includes multiple cable
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Structured Cabling Systems, Standards, and Codes 893
runs to each workstation, it can represent the largest concentration of cable in the build-
ing infrastructure. A building with a 1000 workstations easily can contain a horizontal
cable system consisting of 2000 to 3000 individual cable runs.
Horizontal cabling includes the copper or optical fiber networking media that is used
in the area that extends from the wiring closet to a workstation (see Figure A-10).
Horizontal cabling includes the networking medium that runs along a horizontal path-
way to the telecommunications outlet or connector in the work area, and the patch
cords or jumpers in the HC.
Figure A-10 Horizontal Cabling and Symbols
Any cabling installed between the MC and another TR is known as backbone cabling.
The difference between horizontal and backbone cabling is defined clearly in the
standards.
Lab Activity Terminating a Category 5e Cable on a Category 5e Patch Panel
In this lab, you terminate a Category 5e cable on a Category 5e patch panel
and learn the proper use of a 110 punch-down tool as well as a cable stripper.
X

X
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894 Appendix A: Structured Cabling
Backbone Cabling
Any cabling installed between the MC and another TR is known as backbone cabling.
The difference between horizontal and backbone cabling is clearly defined in the stan-
dards. Backbone cabling is also referred to as vertical cabling. It consists of the back-
bone cables, intermediate and main cross-connects, mechanical terminations, and
patch cords or jumpers used for backbone-to-backbone cross-connection. Backbone
cabling includes the following:
■ TRs on the same floor (MC to IC, IC to HC)
■ Vertical connection (risers) between TRs on different floors (MC to IC)
■ Cables between TR and demarcation point
■ Cables between buildings (interbuilding) in a multibuilding campus
The maximum distances for cabling runs vary from one type of cable to another. For
backbone cabling, the maximum distance for cabling runs also can be affected by how
the backbone cabling is to be used. To understand what this means, assume that a
decision has been made to use single-mode fiber-optic cable for the backbone cabling.
If the networking media were to be used to connect the HC to the MC, then the maxi-
mum distance for the backbone cabling run would be 3000m (9842.5 ft).
At times, the maximum distance of 3000m (9842.5 ft) for the backbone-cabling run must
be split between two sections, as when the backbone cabling is to be used to connect the
HC to an IC and the IC to the MC. When this occurs, the maximum distance for the
backbone cabling run between the HC and the IC is 300 m (984 ft). The maximum dis-
tance for the backbone cabling run between the IC and the MC is 2700 m (8855 ft).
Fiber-Optic Backbone
Fiber optics are an extremely effective means of moving backbone traffic. This is because
optical fibers are impervious to electrical noise and radio frequency interference. Fiber
also does not conduct currents that can cause ground loops. Fiber-optic systems also
have high bandwidth and can work at high speeds. This means that a fiber-optic back-

bone with certain characteristics that is installed today can be upgraded in the future
to even greater performance when the terminal equipment is available. This can make
fiber optic very cost-effective.
Fiber has an additional advantage when used as a backbone medium: It can go much
farther than copper. Multimode optical fiber used as a backbone can support lengths
of up to 2000m. Single-mode fiber-optic cables can go up to 3000m. Although optical
fiber, especially single-mode fiber, can carry signals much farther than this (60 to 70 miles
is feasible, depending on terminal equipment), these longer distances are considered to
be out of the scope of LAN standards.
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Structured Cabling Systems, Standards, and Codes 895
MUTOAs and Consolidation Points
Raised floors and dropped ceilings also can hold patch panels. These typically are used
to house consolidation points or multiuser telecommunications outlet assemblies
(MUTOAs).
Additional specifications for horizontal cabling in work areas with moveable furniture
and partitions have been included in TIA/EIA-568-B.1. Horizontal cabling methodologies
are specified for “open-office” environments by means of MUTOAs and consolidation
points (see Figure A-11). These methodologies are intended to provide increased flexi-
bility and economy for installations with open-office workspaces that require frequent
reconfiguration.
Rather than replacing the entire horizontal cabling system feeding these areas, a CP or
MUTOA can be located close to the open office area and eliminate the need to replace
the cabling all the way back to the TR whenever the furniture is rearranged. The cabling
only needs to be replaced between the new work area outlets and the CP or MUTOA.
The longer distance of cabling back to the TR remains permanent.
Figure A-11 Typical MUTOA Installation
A MUTOA is a device that enables users to move and add devices and to make changes
in modular furniture settings without rerunning the cable. Patch cords can be routed
directly from a MUTOA to work-area equipment (see Figure A-12). A MUTOA loca-

tion must be accessible and permanent, and it cannot be mounted in ceiling spaces or
under access flooring. Similarly, it cannot be mounted in furniture unless that furniture
is secured permanently to the building structure.
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896 Appendix A: Structured Cabling
Figure A-12 Typical Consolidation Point Installation
When using MUTOAs, the TIA/EIA-568-B.1 standard specifies the following:
■ At least one MUTOA is needed for each furniture cluster.
■ A maximum of 12 work areas can be used for each MUTOA.
■ Patch cords at work areas shall be labeled on both ends with unique identifiers.
■ The maximum patch cord length is 22m (72.2 ft.).
Consolidation points (CP) provide limited area connection access. Typically, a perma-
nent, flush, wall-mounted, ceiling-mounted, or support column-mounted panel serves
modular furniture work areas. The panels must be unobstructed and fully accessible
without moving fixtures, equipment, or heavy furniture. Consolidation points differ
from MUTOAs, in that workstations and other work area equipment do not plug into
the CP like they do with the MUTOA. Workstations plug into an outlet that then is
connected to the CP.
The TIA/EIA-569 standard specifies the following:
■ At least one CP for each furniture cluster
■ A maximum of 12 work areas for each CP
■ A maximum patch cord length of 5m (16.4 ft.)
For both consolidation points and MUTOAs, TIA/EIA 568-B.1 recommends a separa-
tion of at least 15 m (49 ft) equipment between the TR and the CP or MUTOa. This is
to avoid problems dealing with crosstalk and return loss.
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Structured Cabling Standards and Codes 897
Structured Cabling Standards and Codes
Standards are sets of rules or procedures that are either widely used or officially speci-
fied, and that serve as the gauge or model of excellence. Standards can take many forms.

They can be specified by a single vendor or can be industry standards that support
multivendor interoperability:
■ Standardized media and layout descriptions for both backbone and horizontal
cabling
■ Standard connection interfaces for the physical connection of equipment
■ Consistent and uniform design that follows a system plan and basic design principles
Numerous companies, organizations, and even government bodies regulate and specify
the cables in use. In addition to these organizations, local, state, county, and national
government agencies issue specifications, requirements, and codes.
The power of standards is this: The network that is built to standards should work well
with, or interoperate with, other standard network devices. The long-term performance
and investment value of many network cabling systems have been severely diminished
by installers who do not know or who follow mandatory and voluntary standards.
It is important to understand that these standards constantly are being reviewed and
periodically updated to reflect new technologies and the ever-increasing requirements
of voice and data networks. Just as new technologies are added to the standards, others
are dropped or phased out. In many cases, a network might include technologies that
are no longer a part of the current standard or that are being eliminated. Typically, this
does not require an immediate changeover, but these older, slower technologies eventu-
ally are replaced in favor of faster ones.
Standards often are developed by or at the direction of international organizations that
try to reach some form of universal standard. Organizations such as the IEEE, ISO,
and IEC are all examples of international standards bodies. These international stan-
dards organizations are composed of members from many nations, each of which has
its own standards-making process.
In many countries, the national codes become the model for state/provincial agencies
as well as municipalities and other governmental units to incorporate into their
laws and ordinances. The enforcement then moves to the most local authority. Always
check with local authorities to determine what codes are enforced. For the most part,
local codes take precedence over national codes, which take precedence over interna-

tional codes.
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898 Appendix A: Structured Cabling
Telecommunications Industry Association and Electronic
Industries Alliances
The Telecommunications Industry Association (TIA) and the Electronic Industries Alli-
ance (EIA) are trade associations that jointly develop and publish a series of standards
covering areas of structured voice and data wiring for LANs (see Figure A-13).
Figure A-13 TIA/EIA Standards for Buildings
N
O
TE
For more information
on TIA and EIA, visit
www.tiaonline.org
and www.eia.org.
Backbone Pathways
Equipment Room
Horizontal Pathways
Entrance Room/Main
Terminal Space
Interbuilding
Backbone
Alternate
Entrance
Antenna Entrance
Telecommunications Room
Backbone Pathways
Service Entrance
Telecommunications

Outlet Box
Work Area
Telecommunications Room
Horizontal Pathways
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