Page 102 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Unit 5: Operations of Network

Category 5e: Used in networks running at speeds up to 1000 Mbps (1 gigabit per second [Gbps]). Notes
Category 6: Typically, Category 6 cable consists of four pairs of 24 American Wire Gauge (AWG)
copper wires. Category 6 cable is currently the fastest standard for UTP.

Figure 5.13: UTP Cable

5.3.2 Shielded Twisted-Pair Cable
Shielded twisted-pair (STP) cable combines the techniques of shielding, cancellation, and
wire twisting. Each pair of wires is wrapped in a metallic foil. The four pairs of wires then
are wrapped in an overall metallic braid or foil, usually 150-ohm cable. As specified for use
in Ethernet network installations, STP reduces electrical noise both within the cable (pair-to-
pair coupling, or crosstalk) and from outside the cable (EMI and RFI). STP usually is installed
with STP data connector, which is created especially for the STP cable. However, STP cabling
also can use the same RJ connectors that UTP uses.
Although STP prevents interference better than UTP, it is more expensive and difficult to
install. In addition, the metallic shielding must be grounded at both ends. If it is improperly
grounded, the shield acts like an antenna and picks up unwanted signals. Because of its cost
and difficulty with termination, STP is rarely used in Ethernet networks. STP is primarily
used in Europe.
The following summarizes the features of STP cable:

Speed and throughput-10 to 100 Mbps
Average cost per node-Moderately expensive
Media and connector size-Medium to large

Maximum cable length-100 m (short)
When comparing UTP and STP, keep the following points in mind:

The speed of both types of cable is usually satisfactory for local-area distances.
These are the least-expensive media for data communication. UTP is less expensive than STP.

Because most buildings are already wired with UTP, many transmission standards are adapted
to use it, to avoid costly rewiring with an alternative cable type.

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