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type of fiber. Depending on the type of twisted pair or fiber optic cables used, data rates today
can range from 100 Mbit/s to 10,000 Mbit/s.
Figure 9.1a Twisted pair cabling includes four pairs of twisted wires, normally connected to a RJ-45 plug at the end.
A rule of thumb is to always build a network with greater capacity than is currently required. To
future-proof a network, it is a good idea to design a network such that only 30% of its capacity
is used. Since more and more applications are running over networks today, higher and higher
network performance is required. While network switches (discussed below) are easy to upgrade
after a few years, cabling is normally much more difficult to replace.
9.1.1 Types of Ethernet networks
Fast Ethernet
Fast Ethernet refers to an Ethernet network that can transfer data at a rate of 100 Mbit/s. It can
be based on a twisted pair or fiber optic cable. (The older 10 Mbit/s Ethernet is still installed and
used, but such networks do not provide the necessary bandwidth for some network video
applications.)
Most devices that are connected to a network, such as a laptop or a network camera, are
equipped with a 100BASE-TX/10BASE-T Ethernet interface, most commonly called a 10/100
interface, which supports both 10 Mbit/s and Fast Ethernet. The type of twisted pair cable that
supports Fast Ethernet is called a Cat-5 cable.
Gigabit Ethernet
Gigabit Ethernet, which can also be based on a twisted pair or fiber optic cable, delivers a data
rate of 1,000 Mbit/s (1 Gbit/s) and is becoming very popular. It is expected to soon replace Fast
Ethernet as the de facto standard.
The type of twisted pair cable that supports Gigabit Ethernet is a Cat-5e cable, where all four
pairs of twisted wires in the cable are used to achieve the high data rates. Cat-5e or higher cable
CHAPTER 9 - NETWORk TECHNOLOGIES
