Practices and usage of twisted pair wires and how to implement standard wire Headers

We may be unfamiliar with the practices and usage of twisted pair wires. For example, it is hard to remember how the standard wire head is implemented. It is also vague to know the cross Line (or direct line) used. Let's talk about some notes.

Prerequisites

1. Twisted Pair pin position definition (the crystal head has no clip side, from left to right), as shown in table 1. For Table 1, we only need to remember two points: one is that only one, two, three, and six eight lines are used, and the other four are used as backups; 2: 1 and 2 are used to send data, and 3 and 6 are used to receive data.

2. Two twisted pair wires: Express wire and crossover wire. The cabling sequence is shown in table 2. Standard connection of qiaoji crystal head

Table 3 has two standard practices for Crystal heads, whether it's TIA/EIA-568A or TIA/EIA-568B, you're trying to remember. Remember? No coincidence. Even if you remember it now, it's just a moment! Note:

1. Coincidence 1: red, green, blue, and brown 46 (TIA/EIA-568B practices)

When the first step is to make the crystal head, the four lines are expanded in the following order: red, green, blue, and Brown (this order is easy to remember: Red, green, and blue are very familiar to people; or, RGB is also a familiar concept, just add a brown color ). At the same time, ensure that the two-color cables are in front of each color network cable, and the monochrome network cable is behind (this rule does not need to be remembered: Double Single, single and double, dual in unit, monochrome in dual). In this way, it is easy to arrange the network cable in such a line Order: safflower → red → green → blue → brown → Brown. It is a bit like a kindergarten teaching material: "safflower, red; green flowers, green; blue flowers, blue; brown flowers, Brown ." Step 2: 4-6 crossover. This is also a good understanding of memory: Because the eight wires are only used by four ends: 1, 2, 3, and 6, these four must be two pairs of twisted pair wires, in order to achieve good anti-interference effect. 1st, 2 (safflower and red) are a pair of twisted pair wires (one is the positive pole for sending data, and the other is the negative pole for sending data), which are already in the positive position and do not need to be adjusted; on the second pair of twisted pair wires (green flowers and green flowers), the green flowers are already on the 3rd-bit, which is the positive pole of the received data, but the green line of the negative pole of the received data is still on the 4th-bit and needs to be adjusted to 6-bit, therefore, 4-6 crossover, that is, completed the TIA/EIA-568B wire head practice.

Summary: red, green, blue, and brown, with lines in front and 4-6 crossed. Further concentrated into seven words: "red, green, blue, and brown 46 ". So as to echo with the following TIA/EIA-568A wire head practice. 2. Coincidence 2: 1326 re-tuning (TIA/EIA-568A practices)

The first step first line by TIA/EIA-568B arrangement, that is: red, green, blue, brown, order spread, flower line in front, 4-6 cross.

The second step 1-3 crossover, 2-6 crossover, that is, completed the TIA/EIA-568A wire head practice. For the sake of note, we can summarize it as: 1326 and then the adjustment.

The purpose of specifying two standard wire headers is to make a standard crossover (one end of the network cable is a TIA/EIA-568B connector, and the other end is a TIA/EIA-568A connector ), to achieve interconnection of the same device port (such as connecting two computers with twisted pair wires), we compare the definition of the twisted pair pin in table 1 (1 and 2 are the positive and negative ends of data transmission, 3, 6 is the positive and negative sides of the received data), it is not difficult to see the data sent by the 1st pin, should be sent to the recipient's receiving port (3rd pin), that is, 1 through 3 (1 to send, 3 ). 2-6 is also a logical principle, which is the negative electrode for sending and receiving data.

Fast identification of twisted pair wires

Get a network cable, experienced network management, the first consciousness is the network cable type-it is a straight line or cross line. So how to quickly identify it?

General experts do the crystal head is a standard approach, that is to say, if the straight line, the two will be made into TIA/EIA-568B standard (simple practice: Only "red, green, brown 46 "); if there is a TIA/EIA-568A joint, most of the cross line.

Of course, it is not ruled out that some people will do both ends are TIA/EIA-568A straight line.

Maybe there are other "Masters" who simply don't rely on any standards, no matter whether they are red, orange, yellow, green, blue, and purple, they directly pass through or cross the four lines of 1, 2, 3, 6. You can quickly identify this network cable at a glance. If it is 1-to-1, it is a straight line; otherwise, 1-to-3 is a cross line.

However, there is a premise for "determining at a glance" to determine the twisted pair cable: The network cable is not wrong; it is neither a direct line nor a cross line. Make sure that the network cable is correct, and check the cables 1, 2, 3, and 6 one by one.

Correct use of twisted pair wires

From the definition of the twisted pair pin in Table 1, we can see that computers and other devices communicate with each other through their respective sending and receiving ports: device A sends data to the receiving port of Device B through the sending port, and A also receives data from the sending port of Device B through the receiving port. Therefore, when the two computers are directly connected, you must use a crossover line-the sending port and the receiving port (1-3, 2-6 ).

This is also the principle of computer network communication. When a computer is connected to another computer through a hub (switch), The Hub (switch) can match the sending port with the receiving port, therefore, the network cable between the computer and the hub (switch) uses a direct connection-the sending port is directly connected to the sending port (1-1, 2-2 ), the receiving port is directly connected to the receiving port (3-3, 6-6). When a hub (switch) and a hub (switch) are cascade through a common port, similar to communication between two separate devices, cross lines must also be used. When cascade through a cascade port, you only need to use a direct connection line.

In short, in general, the device ports are the same, and the cross line is used; otherwise, the direct line is used.