Twisted-Pair Cabling
There are different grades, or categories, of twist-
ed-pair cabling. Category 5 is the most reliable
and widely compatible, and is highly recommend-
ed. Category 3 is a good second choice. Straight-
through cables are used for connecting computers
to a hub. Crossed cables are used for connecting a
hub to another hub (there is an exception: some
hubs have a built-in uplink port that is crossed
internally, which allows you to uplink hubs togeth-
er with a straight cable instead).
You can buy Category 5 cabling that is pre-made,
or cut and crimp your own. Category 5 cables can
be purchased or crimped as either straight-through
or crossed. A Category 5 cable has 8 thin, color-
coded wires inside that run from one end of the
cable to the other. All 8 wires are used. In a
straight-through cable, wires 1, 2, 3, and 6 at one
end of the cable are also wires 1, 2, 3, and 6 at the
other end. In a crossed cable, the order of the
wires change from one
end to the other: wire 1
becomes 3, and 2
becomes 6.
The color code for the 4 wires should be as fol-
lows: Wire 1, white with an orange stripe; Wire 2,
orange; Wire 3, white with a green stripe; Wire 6,
green. The other four wires have to be connected
as follows: Wire 4, blue; Wire 5, white with a blue
stripe; Wire7, white with a brown stripe, Wire 8,
brown.
Appendix
47
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