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Twisted-Pair Cabling
There are different grades, or categories, of twisted-pair cabling. Category 5
is the most reliable and is highly recommended. Category 3 is a good second
choice. Straight-through cables are used for connecting computers to a hub.
Crossover 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 link or connect hubs together with a straight-through
cable instead).
You can buy pre-made Category 5
cabling, 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 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 crossover cable, the order of the
wires change from one end to the
other: wire 1 becomes 3, and 2
becomes 6. See the diagrams on the
next page for more
detailed information on
straight-through and
crossover cabling.
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.
BEFSR41 User Guide Apr 2000.qxd 4/27/00 3:22 PM Page 41