Information Technology Reference
In-Depth Information
Many types of wire and cable are used in LAN wiring. This chapter will describe
the major types of cable that are currently in use. You should define the cable that
will be used long before you begin your cable design. The cable chosen will often
dictate the connectors, terminations, useful distances, routing, and LAN types that
your wiring will support.
We will cover types of cable that are used for all types of networks, including
Ethernet, Token-Ring, and ARCnet. Although we mention these network topologies
and their variations, we will concentrate here on the cable, rather than on its use.
All LAN cable can be divided into three basic types: twisted pair, coax, and fiber optic.
We will cover each of these types in detail. We will also cover round and flat nonpaired
wire often used for telephone sets. However, because nonpaired wire is not used for LAN
wiring, it will be presented only so that you may easily recognize it and avoid its use.
Each basic cable type has several variations, and different types may even be
found in combination. An example of this is twisted-pair cable, which may be found
in unshielded and shielded varieties. There are also several types of nonpaired wire,
such as round 4-wire cable, ribbon cable, and flat cable (often called “silver satin”).
Some manufacturers, such as IBM, specify combination cables that contain both
shielded and unshielded pairs. Even combination fiber-optic and metallic cables are
offered. However, for our purposes here, we will avoid all of the myriad combina-
tions and concentrate on the pure cable types.
Twisted-Pair UTP and STP Cable
Twisted-pair wiring is the most common type of LAN wiring cable in use today. It
is versatile, easy to install, inexpensive, and has favorable performance characteris-
tics. Twisted-pair cable is available with or without shielding. It comes in a variety
of colors, wire gauges, insulation, twisting, and outer sheath materials.
An illustration of twisted-pair wire is shown in Fig. 5.1. A large number of
pairs can be in the same cable sheath (the outer jacket). Telephone cables are com-
monly available in 2-pair, 4-pair, 6-pair, 25-pair, 100-pair, and even larger bundles.
LAN twisted-pair cable, however, usually comes as 4-pair cable.
FIGURE 5.1
Illustration of twisted-pair wire.
