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There are many UTP cables for sale in your favorite computer store, but, it is good to know how to make them. First, there are two standards for the UTP cabling pinouts as defined by the TIA (Telecommunications Industry Association) as well as by EIA (Electronics Industry Alliance). These standards are called: T568A and T568B. Basically, they differ by the order of the wires attached to the RJ-45 connector. For both, T568A & T568B, the wires can be grouped in 4 pairs.

T568A pinouts.

1. Green/White.
2. Green.
3. Orange/White.
4. Blue.
5. Blue/White.
6. Orange.
7. Brown/White.
8. Brown.

T568B pinouts.

1. Orange/White.
2. Orange.
3. Green/White.
4. Blue.
5. Blue/White.
6. Green.
7. Brown/White.
8. Brown.

A straight-through cable uses the same T568x standard in both ends of the RJ-45 connector, while a crossover cable uses one standard on each end of the cable. A straight-through cable is used to connect devices that send/receive on different wires on each end of the cable. On the other hand, a crossover cable connects devices that transmit/receive in the same wires at each end of the cable.