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Appendix E: Twisted-Pair
Cabling
There are different grades, or "categories," of twisted-pair cabling. Category 5
is the most reliable and most highly recommended. Straight-through cables are
used for connecting computers to a hub. Crossover cables are used for con-
necting a hub to another hub (there is an exception: some hubs have a built-in
uplink port that is crossed internally; this allows you to link or connect hubs
together with a straight-through cable instead).
Figure E-1
To determine which wire is wire number 1, hold the cable
so that the end of the plastic RJ-45 tip (the part that goes
into a wall jack first) is facing away from you. Face the
clip down so that the copper side faces up (the springy clip
will now be parallel to the floor). When looking down on
the copper side, wire 1 will be on the far left.
90
Instant Broadband
™
Series
You can buy pre-made Category 5
cables, or cut and crimp your own.
Category 5 cables can be purchased or
crimped as either straight-through or
crossover. Inside a Category 5 cable
are eight thin, color-coded wires
inside that run from one end of the
cable to the other. All eight 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 crossover cable, the
order of the wires change from one
end to the other: wire 1 becomes 3,
and 2 becomes 6. See Figures E-3 and
E-4 on the next page for
more detailed informa-
tion on straight-through
and crossover cabling.
Figure E-2
EtherFast
®
Cable/DSL Router with QoS and 8-Port Switch
.
Crimping Your Own Network Cables
• Straight-Through Cabling
Figure E-3
• Cross-Over Cabling
Figure E-4
91
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