Page 56 - M. Abrahim Thesis

Chapter (3) Networking Media and Data Link Layers Protocols

Figure 3-2 shown a Foil Twisted-Pair Cable Structure

However, shielded cable is more difficult to install than unshielded cable because the
metallic shielding needs to be grounded. If improperly installed, STP and ScTP become very
susceptible to noise problems because an ungrounded shield acts like an antenna, picking up
unwanted signals. STP and ScTP cable cannot be run as far as coaxial and fiber-optic cable
without the use of repeaters. The insulation and shielding considerably increase the size, weight,
and cost of the cable. Despite these disadvantages, shielded copper cable is still used as
networking media today, especially 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 meters (m) (short)

3.2.1.2. Unshielded Twisted-Pair Cable

Unshielded twisted-pair (UTP) cable is a common networking media. It consists of four
pairs of thin, copper wires covered in color-coded plastic insulation that are twisted together, as
shown in Figure below. The wire pairs are then covered with a plastic outer jacket. The connector
used on a UTP cable is called a registered jack 45 (RJ-45) connector, as shown in Figure 3-3.

Figure 3-3 shown a registered jack 45 (RJ-45) connector Structure

Although UTP was once considered to be slower at transmitting data than other types of
cable, this is no longer true. In fact, UTP is considered the fastest copper-based medium today.

The following summarizes the features of UTP cable:

• Speed and throughput—10 to 1000 Mbps

• Average cost per node—Least expensive

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