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Networking: A Beginner's Guide
STP is similar to UTP, but STP has a braided metal shield surrounding the twisted
pairs to further reduce the chance of interference from electrical sources outside
the cable.
Coaxial cable consists of a central copper conductor wrapped in a plastic insulation
material, which is surrounded by a braided wire shield and, finally, wrapped in a
plastic cable sheath. (The coaxial cable used for televisions is similar in design.) Two
main types are used for networks: Thin Ethernet (10Base-2), which uses RG-58/AU or
RG-58/CU cable, and Thick Ethernet (10Base-5), which uses--you guessed it--a much
thicker coaxial cable called RG-8. Figure 4-6 shows an example of coaxial cable.
Fiber-optic cable uses a glass strand and carries the data signals as light instead of
electricity. It used to be that fiber-optic cable was required for higher-speed networks,
but this is changing, and often UTP or STP can be used instead. This is good news, as
fiber-optic cable is extremely expensive to purchase, install, and maintain. However,
fiber-optic cable can do one thing that copper cables cannot: span extremely long
distances. Fiber-optic cable can easily reach two miles at 100 Mbps. For this reason,
fiber-optic cable is often used to connect together buildings in a campus-like setting.
But other than when you need to span very long distances, you should avoid fiber-
optic cable.
Twisted-Pair Cabling: The King of Network Cables
For a number of years, virtually all new networks have been built using some form of
twisted-pair cabling. Usually, Cat-5 grade twisted-pair cable is used, although you may
see some old networks in which Cat-3grade cable is installed. UTP is used instead of
STP in almost all cases, because it's less expensive, easier to install and maintain, and
Figure 4-5.
UTP cable
Twisted pairs
Figure 4-6.
Coaxial cable
Braided metal shield
Conductor
Plastic