Upon completing this chapter, you will be able to:
•
Describe the primary types and uses of twisted-pair cables
•
Describe the primary types and uses of coaxial cables
•
Describe the primary types and uses of fiber-optic cables
•
Describe the primary types and uses of wireless media
•
Compare and contrast the primary types and uses of different media
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8
Network Media Types
Network media
is the actual path over which an electrical signal travels as it moves from
one component to another. This chapter describes the common types of network media,
including twisted-pair cable, coaxial cable, fiber-optic cable, and wireless.
Twisted-Pair Cable
Twisted-pair cable
is a type of cabling that is used for telephone communications and most
modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs
are twisted to provide protection against
crosstalk
, the noise generated by adjacent pairs.
When electrical current flows through a wire, it creates a small, circular magnetic field
around the wire. When two wires in an electrical circuit are placed close together, their
magnetic fields are the exact opposite of each other. Thus, the two magnetic fields cancel
each other out. They also cancel out any outside magnetic fields. Twisting the wires can
enhance this
cancellation effect
. Using cancellation together with twisting the wires, cable
designers can effectively provide self-shielding for wire pairs within the network media.
Two basic types of twisted-pair cable exist: unshielded twisted pair (UTP) and shielded
twisted pair (STP). The following sections discuss UTP and STP cable in more detail.
UTP Cable
UTP cable is a medium that is composed of pairs of wires (see Figure 8-1).
UTP cable is
used in a variety of networks. Each of the eight individual copper w