Networking Guide : Cat 5 Wiring Scheme
EIA and TIA have produced many cable standards that are widely
used in telecommunication and networking. The one that is often referred
to in networking lessons is EIA/TIA-568 that's Commercial Building Telecommunications Cabling
Standard.
EIA/TIA-568 is the basis for Cat 5 cable wiring scheme. Wires inside
a Cat 5 cable are color-coded. There are four pairs of copper wires, but only two pairs are used for transmit and receive. The
pair and pin designation for Cat5 cable is defined in
EIA/TIA-568A
and EIA/TIA-568B. 568A is the original standard which later is
updated by 568B. The difference between 568A and 568B is clearly
illustrated in the table below.
| |
568A |
568B |
| Pair |
Wire |
Pin |
Wire |
Pin |
| 1 |
White/Blue |
5 |
White/Blue |
5 |
| |
Blue |
4 |
Blue |
4 |
| 2 |
White/Orange |
3 |
White/Orange |
1 |
| |
Orange |
6 |
Orange |
2 |
| 3 |
White/Green |
1 |
White/Green |
3 |
| |
Green |
2 |
Green |
6 |
| 4 |
White/Brown |
7 |
White/Brown |
7 |
| |
Brown |
8 |
Brown |
8 |
Table: 568A vs. 568B
Pin and pair designation in two EIA/TIA standards.
This applies to Cat 5, Cat 5e, and Cat 6 cables.
The difference between 568A and 568B wiring scheme is in
pair 2
and pair 3. In 568A, pin 3 (white/orange) and
pin 6 (orange) combine
in pair 2 while pin 1 (white/green) and pin 2 (green) in pair 3. In 568B,
pin 1 (white/orange) and pin 2 (orange) combine in pair 2 while pin 3 (white/green) and
pin 6
(green) in pair 3. Either 568A or 568B wiring scheme can be chosen but
it must be used consistently throughout a network.
page 2 : straight-through cable vs. crossover cable
page 3 : RJ-45 connector pins and crimping tool
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