CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 92 docx

Appendix A
Structured Cabling
This appendix covers the following topics:

■ Structured cabling systems, standards, and codes

■
Safety

■
Tools of the trade

■ The installation process

■
The finish phase

■
The cabling business

■ Case study
Completing this material and the associated labs in the Cisco Networking Academy Program
CCNA 1 and 2 Lab Companion, Third Edition, will provide a broad introduction to all
facets of structured cabling installation.
Structured Cabling Systems, Standards, and Codes
Structured cabling systems refer to telecommunications wiring built in a standardized,
approved manner, starting at the demarcation point, working through the various equip-
ment rooms, and continuing to the work area. The issue of scalability also is addressed.
Items of importance that students should be aware of include these:

■

Rules of structured cabling

■
Subsystems of structured cabling

■ Scalability

■
Demarcation point

■
Telecommunications and equipment rooms

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880 Appendix A: Structured Cabling

■
Work areas

■
MC, IC, and HC

■ Telecommunications Industry Association (TIA) and Electronic Industries
Association (EIA)

■ European Committee for Electrotechnical Standardization (CENELEC)

■
International Organization for Standardization (ISO)

■
U.S. codes

■ Evolution of standards
Rules of Structured Cabling for LANs
Structured cabling is a systematic approach to cabling. It is a method for creating an
organized cabling system that can be easily understood by installers, network adminis-
trators, and any other technicians that deal with cables.
The following three rules help ensure that the structured cabling design projects are
both effective and efficient:

■
Look for a complete connectivity solution—An optimal solution for network
connectivity includes all the systems that are designed to connect, route, manage,
and identify structured cabling systems. A standards-based implementation will
help to make sure that both current and future technologies can be supported.
Following standards makes sure that the project will deliver performance and
reliability over the long term.

■
Plan for future growth—The number of circuits installed should meet these
future requirements as well. Category 5e, Category 6, and fiber-optic solutions
should be considered where feasible to ensure that future needs will be met. It
should be possible to plan a physical layer installation that works for ten or more
years.

■
Maintain freedom of choice in vendors—Even though a closed and proprietary
system may be less expensive initially, this could end up being much more costly
over the long term. A non-standard system from a single vendor may make it

more difficult to to make moves, adds, and changes at a later time.
More Information
For more information on the rules of structured cabling, visit
www.panduitncg.com/NCG_SYSSOL/ncg_syssol_pm/ncg_syssol_pm_markets/Finance/rules.asp.

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Structured Cabling Systems, Standards, and Codes 881
Subsystems of Structured Cabling
Seven subsystems are associated with the structured cabling system (see Figure A-1).
Each subsystem performs certain functions to provide voice and data services through-
out the cable plant.
Figure A-1 Subsystems of Structured Cabling
Backbone Pathways
Equipment Room
Horizontal Pathways
Entrance
Room/Main
Terminal Space
Interbuilding
Backbone
Alternate
Entrance
Antenna Entrance
Telecommunications Room
Backbone Pathways
Demarcation Point
Telecommunications
Outlet Box
Work Area
Telecommunications Room

Horizontal Pathways

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882 Appendix A: Structured Cabling

■
The demarcation point (demarc) within the entrance facility (EF) in the equip-
ment room

■
The telecommunications room (TR)

■
Backbone cabling, also known as vertical cabling

■ Distribution cabling, also known as horizontal cabling

■
The work area

■
Equipment room (ER)

■ Administration
The demarc is where the outside service provider cables connect to the customer’s
cables in the facility.
Backbone cabling is the feeder cables that are routed from the demarc to the equip-
ment rooms and then on to the telecommunications rooms throughout the facility.
Horizontal cabling distributes cables from the telecommunication rooms to the work
areas. The telecommunications rooms are where connections take place to provide a

transition between the backbone cabling and horizontal cabling.
These subsystems make structured cabling, by nature, a distributed architecture with
management capabilities that are limited to the active equipment (PCs, switches, hubs,
etc.). Designing a structured cabling infrastructure that properly routes, protects, iden-
tifies and terminates the copper or fiber media is absolutely critical for network perfor-
mance and future upgrade.
Scalability
A LAN that can accommodate future growth in size is referred to as being scalable. It
is important to plan ahead when estimating the number of cable runs and cable drops
in a work area. It is always easier to ignore extra installed cables than to not have them
when they are required.
In addition to pulling extra cables in the backbone area for future growth, it is also
common practice to pull an extra cable to each workstation or desktop for future use.
This protects against pairs that might fail during installation and also provides for
expansion.
Backbone Scalability
To determine how much extra copper cabling to pull, first determine the number of
runs that are needed now and then add some extra, about 20 percent.

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Structured Cabling Systems, Standards, and Codes 883
One way to obtain this reserve capability is to use fiber-optic cabling and equipment in
the building backbone. Updating the termination equipment (by inserting faster lasers
and drivers, for example) can accommodate fiber growth.
Work Area Scalability
Although it might be obvious that each work area needs one cable for voice and one
for data, other devices might need a connection to either the voice system or the data
system. Network printers, fax machines, laptops, or another user in the work area all
can require their own network cable drops.
When the cables are in place, use multiport wall plates over the jacks. Many types of

configurations are possible for either walls or partition walls. In addition, use jacks
that are color-coded to make it easier to identify types of circuits. Administration stan-
dards require that every circuit should be clearly labeled to assist in connections and
troubleshooting.
A new technology that is becoming popular is Voice over Internet Protocol (VoIP). This
technology allows special telephones to use data networks when placing telephone
calls. A great advantage to this technology is the capability to avoid costly long-distance
charges by using this service over existing network connections. Other devices, such as
printers and computers, can be plugged into the IP phone. The IP phone thus becomes
a hub or switch for the work area. Even if these types of connections are planned, enough
cables should be installed to allow for growth. Especially consider that IP telephony
and IP video traffic may share the network cables in the future.
To accommodate the changing needs of users in offices, it is recommended to provide
at least one spare cable to the work area outlet. Offices might change from single-user
to multiuser spaces. In these cases, a work area can become inefficient if only one set of
communication cables were pulled. Assume that every work area could accommodate
multiple users in the future (see Figure A-2).
Demarcation Point
The demarcation point (demarc), provides the point at which outdoor cabling inter-
faces with the intrabuilding backbone cabling (See Figure A-3). It represents the
boundary between the service provider’s responsibility and that of the customer. In
many buildings, this is near the point of presence (POP) for other utilities, such as
electricity and water.

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884 Appendix A: Structured Cabling
Figure A-2 Allow for Growth
Figure A-3 Demarcation Point
The service provider is responsible for everything from the demarc to the service
provider’s facility. Everything from the demarc into the building is the customer’s

responsibility.

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Structured Cabling Systems, Standards, and Codes 885
The local telephone carrier typically is required to terminate cabling within 15m (49.2 ft.)
of building penetration and to provide primary voltage protection. This usually is
installed and provided by the service provider.
The Telecommunications Industry Association (TIA) and Electronic Industries Associ-
ation (EIA) develop and publish standards for many industries, including the cabling
industry. To ensure that the cabling installation is safe, is installed correctly, and retains
performance ratings, these standards always should be followed when performing any
voice or data cabling installation or maintenance.
TIA/EIA-569-A specifies the standards for the demarc space. The standards for the
structure and size of the demarc space are based on the size of the building. In buildings
larger than 2000 usable square meters, a locked, dedicated, and enclosed room is rec-
ommended.
The following are general guidelines when setting up a demarcation point space:

■
Allow 1m
2
of plywood wall mount for each 20m
2
(215.3 ft
2
) area of floor space.

■
The surfaces where the distribution hardware is mounted must be covered with
fire-rated plywood or plywood that is painted with two coats of fire-retardant

paint.

■
Either the plywood or the covers for the termination equipment should be col-
ored orange to indicate the point of demarcation.
Telecommunications and Equipment Rooms
After the cable enters the building through the demarc, it travels to the entrance facility
(EF), which is usually in the equipment room (ER). The equipment room is the center
of the voice and data network. An equipment room is essentially a large telecommuni-
cations room that may house the main distribution frame, network servers, routers,
switches, the telephone PBX, secondary voltage protection, satellite receivers, modula-
tors, high-speed Internet equipment, and so on. The design aspects of the equipment
room are specified in the TIA/EIA-569-A standard.
In larger facilities, the equipment room may feed one or more telecommunications
rooms (TR) which are distributed throughout the building (see Figure A-4).
A wiring hub and patch panel in a TR may be mounted to a wall with a hinged wall
bracket, a distribution rack (see Figure A-5), or a full equipment cabinet.

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886 Appendix A: Structured Cabling
Figure A-4 Telecommunications Room
Figure A-5 Panduit Distribution Rack

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Structured Cabling Systems, Standards, and Codes 887

■
If the choice is a hinged wall bracket, the bracket must be attached to the plywood
panel that covers the underlying wall surface. The purpose of the hinge is to allow
the assembly to swing out so that workers and repairmen easily can access the

back side of the wall. Care must be taken, however, to allow 48 cm (18.9 in.) for
the panel to swing out from the wall.

■
If you are using a distribution rack, it must have a minimum of 1 meter (3 feet) of
workspace clearance in the front and rear of the rack. A 55.9-cm (22-in.) floor
plate, used to mount the distribution rack, provides stability and determines the
minimum distance for its final position.

■
If the patch panel, hub, and other equipment are mounted in a full equipment
cabinet, they require at least 76.2 cm (28.6 in.) of clearance in front, for the door
to swing open. Typically, such equipment cabinets are 1.8m high

× .74m wide

×
.66m deep (5.9 ft.

× 2.4 ft.

× 216.5 ft.).
Equipment must be placed in equipment racks with care. Considerations include whether
the equipment uses electricity, cable routing, cable management, and ease of use. For
example, a patch panel would not be placed high on a rack if a significant number of
changes were to take place after the systems were installed. Convenience of use is a
large consideration when planning the equipment layout.
Scalability is also a consideration in an equipment layout because future growth should
be accommodated. Space should be left on a rack for future patch panels, or floor
space should be left for future rack installations in an initial layout.

Proper installation of equipment racks and patch panels in the TR allows easy changes
and modifications to the cabling installation in the future. This is important when con-
sidering the design and layout of the work areas.
Work Areas
The area serviced by an individual telecommunications room is called a work area. In most
cases, a work area occupies one floor or part of one floor of a building (see Figure A-6).
The maximum distance for a cable from the termination point in the TR to the termination
at the work area outlet must not exceed 90 meters (295 ft). This 90 meter maximum
horizontal cabling distance is referred to as the permanent link. Each work area must
have at least two cables, one for data and the other for voice. As previously discussed,
accommodations for other services and future expansion must also be considered.

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888 Appendix A: Structured Cabling
Figure A-6 Work Areas
This distance must be reduced because cables usually cannot be strung across the floor;
they usually ride in wiring-management devices such as trays, baskets, ladders, and
raceways. These devices route the paths of the wires above workspaces, often in the
plenum areas above suspended ceilings. This means that the height of the ceiling times
two (once up to the wiring management device and once back down) must be sub-
tracted from the proposed work area radius.
In addition, ANSI/TIA/EIA-568-B specifies that there can be 5m (16.4 ft.) of patch
cord to interconnect equipment patch panels, and 5m of cable from the cable termina-
tion point on the wall to the telephone or computer. This additional maximum of
10 meters of patch cords added to the permanent link is referred to as the horizontal
channel. The maximum distance for a channel is 100 meters—the 90 meter maximum
permanent link plus 10 meters maximum of patch cords.
Finally, the routes that the cables actually take might not be straight to the destination.
Wiring-management devices can be costly, and the location of heating, ventilation, and
air-conditioning equipment; power transformers; and lighting equipment can dictate

paths that add length. This further decreases the radius of the work area. Typically,
when everything is taken into account, the actual radius might be closer to 60 to 70m
(196.9 to 229.7 ft.) than 100m (328.1 ft.); 50m (164 ft.) commonly is used as a work-
area radius for design purposes.

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