Concept Exercise Chapter 9 Name:
Date: Class:

Cisco Exercises - Semester 1 - Networking Fundamentals
Chapter 9 Structured Cabling



After the decision has been made to network computers in a building, one of the
first things you must address is where the wiring closet will be located. To
determine where the wiring closet will be located, it will help to think of the
hub as the center point of a circle with lines of horizontal cabling radiating
out from it like spokes from the center of a wheel. Then, locate all the
devices that will be connected to the network on a floor plan of the building
that is drawn approximately to scale. As you do this, remember that computers
will not be the only devices you will want to connect to the network. You must
also consider the location of printers and file servers that will be part of
the network.

When you are connecting cable to jacks, remember to strip back only as much of
the cable's jacket as is required to terminate the wires. The more wire that is
exposed, the poorer the connection will be. This will result in signal loss. In
addition, maintain the twists in each pair of wires as close as possible to the
point of termination. As you will learn in Chapter 22, it is the twisting of
the wires that produces cancellation, which is needed to prevent radio and
electromagnetic interference. For Category 4 UTP, the maximum amount of
untwisting that is allowed is I inch. For Category 5 UTP, the maximum amount of
untwisting that is allowed is V2inch.

If you must bend cable in order to route it, be sure to maintain a maximum bend
radius of four times the diameter of the cable. Never bend cable to the extent
that it exceeds a 90-degree angle.

If multiple cables are run over the same path, use cable ties to cinch them
together. When cable ties are needed to mount or secure cable, be sure to apply
cable ties so they can slide a little. Position ties at random intervals along
the cable. Never secure the cable ties too tightly; this can damage the cable.
When securing the cable ties, try to minimize the amount of jacket twisting. If
cable is twisted too much, it can lead to tom cable jackets.

Never allow the cable to be pinched or kinked. If this occurs, data will move
more slowly and your LAN will operate at less than optimal capacity.

When handling the cable, avoid stretching it. If you exceed 25 pounds of pull,
wires inside the cable can untwist. As you have learned, if wire pairs become
untwisted, this can lead to interference and crosstalk. Above all, never cut
comers with cable. It is important to leave ample slack. Remember, a few feet
of extra cable is a small price to pay to avoid having to redo a cable run
because of mistakes resulting in stretched cable. Most cable installers avoid
this problem by leaving enough slack so that the cable can reach the floor and
extend another two or three feet at both ends of the cable. Other installers
follow the practice of leaving a service coil, which is nothing more than a few
extra feet of cable left coiled up inside the ceiling or in another
out-of-the-way location. Use appropriate and recommended techniques for
dressing and securing the cable. These include cable ties, cable support bars,
wire management panels, and releasable Velcro straps. Never use a staple gun to
position cables. Staples can pierce the jacket resulting in loss of
connection.

Concept Questions

Demonstrate your knowledge of these concepts by answering the following
questions in the space provided.

Generally speaking, the wiring closet must be large enough to accommodate the
equipment and wiring located in it. How do you determine how large the closet
should be?






Naturally, this will vary with the size of the LAN and the types of equipment
required to operate it. Equipment required for some small LANs might take up as
little space as a large filing cabinet, while a large LAN could require a full
fledged computer room.

Finally, the wiring closet must be large enough to accommodate future growth.
How do you estimate the future growth of a network?





EIAMA-569 specifies that there be a minimum of one wiring closet per floor and
states that additional wiring closets should be provided for each area up to
1000 square meters when the floor area served exceeds 1000 square meters or the
horizontal cabling distance exceeds 90 meters. Hint: 1000 square meters equals
10,000 square feet. Ninety meters equals approximately 300 feet.

Anytime you install cable, it is important to document what you have done.
Therefore, as you install cable, be sure to make a cut sheet. A cut sheet is a
rough diagram that shows where cable runs are. It also indicates what the
numbers of the schoolrooms, offices, or other rooms are where the cable runs
lead to. Draw and document the cabling for a small LAN. Include three terminals
in three different rooms and provide for Internet access.









Later, you can refer to this cut sheet so that corresponding numbers can be
placed on all telecommunications outlets and at the patch panel in the wiring
closet. You can use a page in your journal to document cable runs. By placing
it in your journal, you have an additional layer of documentation for any cable
installation.

EIA/TIA-606 specifies that some kind of unique identifier must be given to each
hardware termination unit. This identifier must be marked on each termination
hardware unit or on its label. When identifiers are used at the work area,
station terminations must be labeled on the faceplate housing, or on the
connector itself. Whether they are adhesive or insertable, all labels must meet
legibility, defacement and adhesion requirements. Label the drawing that you
did earlier in this exercise with the identifier to each hardware termination
unit.