Information Technology Reference
In-Depth Information
wire 8-in modular connectors are certainly available, but they are impossible to dis-
tinguish without close examination, and most installers recommend against their
use. A better approach is to simply use the same patch panel or punchdown that ter-
minates the station cables to terminate the backbone cables. Mark the backbone
cable patch position clearly to differentiate it.
You may wish to more clearly identify backbone wiring by using cable colors,
cross-connect/patch panel colors, and special markings. These colors and markings,
identified in EIA/TIA-569-A, are covered in later chapters.
If your backbone wiring actually involves floor-to-floor cabling in vertical
shafts or cable ports, you may need to use special riser cable that has a fire-retar-
dant sheath, certified to meet NEC low-flame requirements.
The NEC requires that riser cable meets UL flammability tests to be used in
high-rise buildings. Local regulations may supplement or amend these requirements.
Local building inspectors should be able to advise you about the requirements in
your area.
As a last word on backbone wiring, fiber-optic cable may provide some signif-
icant advantages over copper. Fiber-optic cable is not subject to electrical or mag-
netic interference, and thus may be run in locations, such as elevator shafts or
alongside power lines, that would cause problems for metallic cable. In addition, a
cabling system may be electrically isolated between buildings or between floors of
the same building by using fiber-optic cable. Metallic cable, on the other hand, must
be carefully installed with adequate consideration of grounding and bonding.
Fiber-optic cable may also be used for multiple applications with the use of
fiber optic multiplexers (WDM, wave-division multiplexing). Thus, it would be pos-
sible for one fiber-optic connection to carry Ethernet, Token-Ring, T1, ATM, and
FDDI all at the same time. Fiber-optic cabling must meet the same plenum and riser
specifications as metallic cable.
Location and Routing. The importance of location and routing of your cabling
system components depends upon the level of cable facility that you intend to
install.
Category 3 installations have much more flexibility in routing than Category
5e/Category 6 installations. For networks that must provide 100 to 1000 Mbps
speeds, and have horizontal runs that approach the 90 m limit, you must be very
attentive to installation details. Location and routing of the station cables are criti-
cal to high-performance operation.
TRs should be located so that they are within 90 m “as the cable runs” from
the proposed workstation outlets that are to be served. In some cases, the number of
TRs may have to be increased or relocated to stay below this distance. A scaled plan
Search WWH ::




Custom Search