The first thing to know is the overall function of the eight copper wires, which are intertwined together according to a certain density in order to reduce the interference of electromagnetic signals with each other. In this way, the radio waves radiating from each other during the transmission of electrical signals cancel each other out, which is useful for eliminating disturbances. The name twisted pair is also derived from this construction.
The earliest use of twisted pair was used for the transmission of telephone signals, and then it was gradually introduced into the transmission of digital signals, and now it is widely used in super five types of twisted pair and six types of twisted pair. Both Category 5 and Category 6 lines can reach a bandwidth of 1000Mbps. The only disadvantage of twisted pair cable is that the transmission interval is short, generally it can reach 100 meters, and the good line is about 120 meters.
Generally, Category 5 super twisted pair cables require the use of four pairs of wires, that is, 8 cores. BELOW 100M, 1, 2, 3, 6, four wires are generally used.
Positive line (standard 568B): The line sequence at both ends is the same, the line order is: orange-white, orange, green-white, blue, blue-white, green, brown-white, brown.
Reverse line (568A): One end is the line sequence of the positive line, and the other end is: green-white, green, orange-white, blue, blue-white, orange, brown-white, brown.
There is no need to remember the monitoring according to the 568A line sequence, one is no longer used in this line sequence, and another one, on the basis of 568B, 13 and 26 can be reversed.
Why do you use 1236 four wires, then you need to understand what the role of each core is:
1 Output Data (+)
2 Output data (-)
3 Input Data (+)
4 Reserved for telephone use
5 Reserved for telephone use
6 Input Data (-)
7 Reserved for telephone use
8 Reserved for telephone use
It can be seen that although the twisted pair has 8 cores, in the currently widely used 100 Gigabit network, only 4 of them are actually used, namely the 1st, 2nd, 3rd, and 6th, which play the role of receiving and sending signals respectively. 4, 5, 7, 8 are two-way lines and are reserved for use.
However, under the network operation higher than 100M, usually the eight cores will be fully used, such as the six types of super six network cables not only need to use 1 3 2 6, but also the eight cores need to be used, otherwise the network operation will be unstable.
Peeling off the network cable, we can find that the density of the four pairs of twisted pair cables is not the same, the orange and green pairs used to transmit data, the number of winding circles is significantly larger than the brown and blue pairs used for grounding and other public purposes, so it is recommended that when you usually do jumpers, they are arranged in strict accordance with the order of 568B.
In fact, there is a key problem: now many bad businesses, in the production of network cables, only four of the 8 cores are made of pure copper, and the remaining four cores are not copper-clad aluminum, copper-clad steel, or even copper-clad iron.
A friend said, "I like to use the order I am used to to making lines, can I also use it?"
You can use this at home, if you are still strict in the project, follow the line order. Otherwise, the role of the twisted pair is lost. The data transmission attenuation is serious, and the transmission distance is greatly reduced.