The network cable uses four core wires: 1, 2, 3, and 6.
1-3, 2-6 cross connection. Although the twisted pair cable has 4 pairs of 8 core wires, in fact only 4 of them are used in the network, namely the 1st, 2nd, 3rd, and 6th pins of the crystal head, which play the role of receiving and sending signals respectively. The core wire arrangement rule of this crossover network cable is:
The 1st pin of one end of the network cable is connected to the 3rd pin of the other end, and the 2nd pin of one end of the network cable is connected to the 6th pin of the other end, and the other pins can be matched one by one. This arrangement is usually called a "cross cable.
For example, when the order of the core wires from left to right at one end of the cable is: white-green, green, white-orange, blue, white-blue, orange, white-brown, brown, the order of the core wires from left to right at the other end should be: white-orange, orange, white-green, blue, white-blue, green, white-brown, brown.
100M connection method. This is the most commonly used network cable production rule. The so-called 100M connection method means that it can meet the communication rate of 100M bandwidth. Although its connection method is also one-to-one correspondence, the color of each pin is fixed. Specifically:
Pin 1 - orange and white, pin 2 - orange, pin 3 - green and white, pin 4 - blue, pin 5 - blue and white, pin 6 - green, pin 7 - brown and white, pin 8 - brown. It can be seen that the 4 pairs of core wires of the network cable are not all arranged adjacently. Pins 1, 3, 5 and 7 include 2 pairs of core wires, but the order is messed up.