Information Technology Reference
In-Depth Information
All of the wiring from workstations to telecommunications rooms and between
telecommunications rooms is referred to as “horizontal” wiring and “backbone”
wiring, respectively, in the terminology of structured wiring. Backbone wiring is
sometimes called
vertical wiring
. If we envision workstations on each floor of a
building, and wiring closets vertically stacked with one per floor, this terminology
makes sense. However, multiple telecommunications rooms are often located on the
same floor, so the term “backbone” is clearer than the term “vertical”—the wiring
from workstation to telecommunications room is the horizontal wiring and the
wiring between rooms is the backbone wiring. If we also have additional telecom-
munications rooms, such as the intermediate and main cross-connect rooms, the
wiring between those rooms is also called backbone wiring. This terminology holds
whether the rooms are on multiple floors or are on the same floor.
The TIA standards always use the term
backbone
to refer to wiring between
telecommunications rooms. Unfortunately, backbone has a very different meaning
in LAN systems as compared to telephone systems. A LAN backbone is a logical
subdivision of a network that has nothing to do with where the wiring goes. In fact,
wiring on the same LAN backbone segment can be in two or more telecommunica-
tions rooms, or two LAN backbones can be in the same telecommunications room.
However, we will stick to the wording in the standards and refer to all wiring
between telecommunications rooms as backbone wire (or cable), unless we are
specifically referring to that portion of a LAN system that interconnects multiple
LAN hubs or bridges.
Color Coding the Telecommunications Room
TIA 569-B recommends that the cross-connects in a telecommunications room be
grouped together, and prescribes a color code to further show this grouping. Table
14.1 shows the recommended colors for various terminations and cross-connect
locations. For the cross-connect locations, the standard generally uses traditional
colors, such as orange for the telco demarcation punch blocks, and blue for the sta-
tion cable punchdown locations. Actually, the punch block itself is usually white,
but its cover or mounting board may have the code color.
The standard also recommends that different jacket colors be used on the
cables to distinguish between the usage types of the cables. This presents an inter-
esting dilemma, as the colors in the standard bear little resemblance to the tradi-
tional colors used in commercial cabling. For example, station wire (to the
workstation) has traditionally been run in beige or gray (the plenum-rated default),
