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Media
- (February - 2009)
An
important part of designing and installing an Ethernet is
selecting the appropriate Ethernet medium. There are four major
types of media in use today: Thickwire for 10BASE5 networks,
thin coax for 10BASE2 networks, unshielded twisted pair (UTP)
for 10BASE-T networks and fiber optic for 10BASE-FL or
Fiber-Optic Inter-Repeater Link (FOIRL) networks.
This wide
variety of media reflects the evolution of Ethernet and also
points to the technology's flexibility. Thickwire was one of the
first cabling systems used in Ethernet but was expensive and
difficult to use. This evolved to thin coax, which is easier to
work with and less expensive.
The most
popular wiring schemes are 10BASE-T and 100BASE-TX, which use
unshielded twisted pair (UTP) cable. This is similar to
telephone cable and comes in a variety of grades, with each
higher grade offering better performance.
Level 5 cable is the highest, most expensive grade, offering
support for transmission rates of up to 100 Mbps. Level 4 and
level 3 cable are less expensive, but cannot support the same
data throughput speeds; level 4 cable can support speeds of up
to 20 Mbps; level 3 up to 16 Mbps.
The 100BASE-T4 standard allows for support of 100 Mbps Ethernet
over level 3 cable, but at the expense of adding another pair of
wires (4 pair instead of the 2 pair used for 10BASE-T); for most
users, this is an awkward scheme and therefore 100BASE-T4 has
seen little popularity. Level 2 and level 1 cables are not used
in the design of 10BASE-T networks.
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