A network cable is terminated with eight wires – usually to a jack plug, or socket – using a specification – T568. T568 has two different specifications: T568A and T568B.
T568A uses the following pin layout:
- Green / White
- Green
- Orange / White
- Blue
- Blue White
- Orange
- Brown / White
- Brown
T568B uses the following pin layout:
- Orange / White
- Orange
- Green /White
- Blue
- Blue / White
- Green
- Brown / White
- Brown
To make a standard patch cable, you simply select one of the specifications, and terminate both ends of the cable the same. It doesn’t matter which version you use, as long as you are consistent with the layout.
These cables are usually the most common. They are used to connect most devices to devices such as routers, switches and hubs. This type of cable is commonly referred to as a straight-through cable. This is because the wiring doesn’t change from one end to the other.
However, there is a different type of cable, which is less common. This is known as a crossover cable. It is often used to connect two devices, such as a PC, to each other directly.
This cable is slightly different because one end is terminated with T568A and the other end is terminated with T568B – crossing over the transmit and receive pins. This is useful where you simply want two devices to send information to each other – the respective devices always sends data on pins 1 and 2, and listen to receive data on pins 3 and 6.