Appendix
Twisted-Pair Cabling
There are different grades, or categories, of twisted-
pair cabling. Category 5 is the most reliable and wide-
ly compatible, and is highly recommended. 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 together 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 pur-
chased 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 follows:
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.
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