Information Technology Reference
In-Depth Information
kbps, T1 or E1, and many other telephone services are also compatible with struc-
tured wiring systems. Also, several products to distribute video over twisted pair in
NTSC format have been introduced, and you can even distribute IBM-5250 and -
3270 terminals over the same wiring system.
Such a wide range of uses makes the term “generic” seem totally inadequate.
Perhaps
multipurpose
or
general use
would better describe this structured cabling
system.
The true versatility of the TIA/EIA-568-C wiring system is a powerful advan-
tage to any organization that uses it. For this reason, you should be wary of com-
promises that limit your wiring system's utility. Although you may have a very
specific purpose in mind, who can say to what use the wiring system will be put over
its useful life of 10 or 20 years?
International standards also cover much of the same ground. For the most
part, these standards are all coordinated. It would be tiresome indeed to constantly
list all of the coordinated or referenced standards for each citing. Therefore, we will
simply use the U.S. standard number in most cases. A fairly complete list of U.S.,
Canadian, European Community, and International standards is given in the appen-
dix of this topic. Standards that are coordinated are so noted. The structural wiring
system comprises several component structures. Within a building, the structures
are called horizontal and backbone wiring.
Structured wiring defines a series of wiring elements that are assembled and con-
nected to form telecommunications links (Fig. 1.2). The basic elements are the
hor-
izontal wiring structure
, the
backbone wiring structure
, and a series of
cross-connect
structures
that include the
main cross-connect
, the
intermediate cross-connect
, and
the
horizontal cross-connect
. These last three elements are usually contained in ded-
icated rooms within a building.
For example, the horizontal cross-connect is contained in the TR, and is iden-
tified as such. The other rooms are often identified by their structure names, main
cross-connect (MC) or intermediate cross-connect (IC). Backbone cable runs
between the cross-connect structures, while horizontal wiring runs from the TR to
the individual work areas.
This hierarchy is illustrated in Fig. 1.3. The structure holds within a single
commercial building and between buildings, as on a campus.
Although the structured wiring concept actually comes from the telephone
industry, and thereby predates data uses of twisted-pair cabling, its use is particu-
larly critical to modern data networks. Structured wiring defines the precise maxi-
