Crossed twisted pair: twisted pair with 568A standard at one end and 568B standard at the other end.
568A cable arrangement sequence: white green, green, white orange, blue, white blue, orange, white brown and brown.
568B cable arrangement sequence: white orange, orange, white green, blue, white blue, green, white brown and brown.
For 568A and 568B, there is no essential difference between them, only the difference in color. The basic problem is to ensure that:
(1) 1 and 2 pairs are a winding pair.
(2)3 pairs and 6 pairs are winding pairs.
(3) Four pairs and five pairs are a winding pair.
(4)7 pairs and 8 pairs are a winding pair.
(1) When networking with hubs or switches, both ends of a line must be made of the same standard, and it is best to make only one standard network cable on the same hub or switch;
(2) When there are only two computers without hubs or switches, one end of the network cable should adopt the 568A standard and the other end should adopt the 568B standard. This is because pins 1 and 2 of the network card are used to send data, while pins 3 and 6 are used to receive data. Two different standards just correspond to feet 1, 2, 3 and 6.
(3) No matter how close the physical distance between the two computers is, practice has proved that the length of the network cable should be greater than 1.5m, otherwise the data transmission will be intermittent.
Crosshairs must be used in the following situations:
1, when two computers are directly connected through a network card (so-called direct connection between two computers);
2. When the public ports of hubs or switches are cascaded together;
A straight line must be used in the following cases:
1. When the computer is connected to a hub or switch;
2. When a hub or switch is connected to a public port of another hub or switch through an uplink port;
3. When the hub or switch is connected to the LAN port of the router;
In the following cases, you can use straight lines or intersecting lines:
1, RJ-45 port of hub or switch has polarity identification function, which can automatically judge the equipment connected at the other end and automatically realize the switching between MDI/MDI-II;
2. The MDI/MDI-II switch of a specific port of a hub or switch can be switched to choose to use a straight line or a crossover line to connect other hub devices.