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4. Specifications
4.1. Cable specifications
The related cables specification shown in the following table
Cable Type
Cable Requirements
Maximum Length
1000BASE-T
Category 5e or better, UTP or STP
328 ft (100M)
RJ11
6P4C (six position, four conductor),
100Mbps@984ft
(300M)
Twisted-pair cabling comes in various grades, or categories. Category 5 is
required for Fast Ethernet, and is also the most reliable and most commonly
used category. You can buy UTP Category 5 (Unshielded Twisted Pair)
Ethernet cabling in precrimped lengths, or you can crimp your own. Crimping
your own can result in faulty connections if the
RJ-45 tips are not attached properly. Precrimped Category 5 cabling is
available at most computer retail stores.
The most reliable and commonly used type of Category 5 cabling used is UTP,
or "unshielded twisted pair." STP or "shielded twisted pair" wiring is only
necessary for network environments exposed to excessive amounts of
electromagnetic interference, or EMI. These environments include areas with
high sources of electrical power, air conditioning, generators, and radio signals.
STP is also used for wiring outdoors.
There are two types of the wiring: Straight-Through Cables and Crossover
Cables. Category 5 UTP/STP cable has eight wires inside the sheath. The
wires form four pairs. Straight-Through Cables has same pin outs at both ends
while Crossover Cables has a different pin arrangement at each end.
In a straight-through cable, wires 1,2,3,4,5,6,7 and 8 at one end of the cable
are still wires 1~8 at the other end. In a crossover cable, the wires of 1,2,3,6
are reversed so that wire 1 become 3 at the other end of the cable, 2 becomes
6, and so forth.
To determine which wire is wire 1, hold the RJ-45 cable tip with the spring clip
facing towards the ground and the end pointing away from you. The copper
wires exposed upwards to your view. The first wire on the far left is wire 1. You
can also refer to the illustrations and charts of the internal wiring on the
following page.
There are two types of cables: Straight Through Cables and Crossover Cables.
Category 5 UTP/STP cable has eight wires inside the sheath. The wires form
four pairs. Straight Through Cables has same pin outs at both ends while
Crossover Cables has a different pin arrangement at each end.
Figure 4-1 shows the diagram of Straight Through Cables. Figure 4-2 shows
the diagram of Crossover Cables. Figure 4-3 shows the diagram of RJ-11
