Brief Introduction of network connection method (direct connection, crossover, and full anti-line)

Twisted Pair wiresThere are generally three sort orders:Pass-through(Straight-through ),Crossover(Cross-over) andAnti-DDoS pro(Rolled)

1.Pass-throughA straight-through line is generally used to connect two interfaces of different properties. Generally used for: PC to switch/hub, router to switch/hub. The straight-through method is to make the two ends of the line order the same, either both ends are 568a standard, or both ends are 568b standard.

Hub/switch host
1 <------------> 1
2 <------------> 2
3 <------------> 3
6 <------------> 6

2.CrossoverThe (cross-over) line is generally used to connect two ports of the same nature. For example, switch to switch, switch to hub, hub to hub, host to host, and host to router. The practice is that the two ends are different, one end is made into 568a, and one end is made into 568b.

Hub/switch hub/Switch
1 <------------> 3
2 <------------> 6
3 <------------> 1
6 <------------> 2

3.Anti-DDoS proRolled is not used for Ethernet connections. It is mainly used for the console line connected to the serial port of the host and the Console port of the router (or switch. In practice, the order of one end is 1-8, and that of the other end is 8-1.

Host router/Switch
1 <------------> 8
2 <------------> 7
3 <------------> 6
4 <------------> 5
5 <------------> 4
6 <------------> 3
7 <------------> 2
8 <------------> 1

Supplement:
The wiring standards of EIA/TIA define the line sequence 568a and 568b of the two twisted pair wires.
(1) 568a standard:
Green white -- 1, green -- 2, orange white -- 3, blue -- 4, blue white -- 5, orange -- 6, brown white -- 7, brown -- 8
(2) 568b standard:
Orange white -- 1, orange -- 2, green white -- 3, blue -- 4, blue white -- 5, green -- 6, brown white -- 7, brown -- 8
("Orange White" refers to light orange, or cables with orange dots or bars on the white line. The same applies to green white, brown white, and blue white ).

Note:The sequence of twisted pair and the serial number of the RJ45 head must be one-to-one.

To maintain optimal compatibility, the EIA/TIA 568b standard is widely used to create network cables. Note: Only one network cable standard should be used in the entire network wiring. If the standards are not uniform, several people may be confused when working together. More seriously, once a cable error occurs during the construction process, it is difficult to find and remove the bundled cables. I strongly recommend that the 568b standard be adopted.
In fact, 10 M Ethernet cables only use 1, 2, 3, 6 Core lines to transmit data, that is, 1, 2 for sending, 3, 6 for receiving, in color: orange and orange are used for sending; green and green are used for receiving; 4, 5, 7, and 8 are bidirectional lines.
M and M NICs need to use four pairs, that is, all eight core wires are used to transmit data. Because 10 m NICs can be made in M mode, and the twisted pair wires provide four pairs, the 10 m NICs are generally made in M mode.
In addition, according to the different network devices connected to the two ends of the network cable, the network cable can be divided into two types: Direct Line (parallel line) and cross line. A straight-through line (parallel line) is a network cable created according to the 568a or 568b standards described earlier. On the other hand, the line sequence of the crossover line changes a little on the basis of the straight-through line, that is, one and three pairs and two and six pairs at one end of the cable. That is to say, the end of the crossover line remains unchanged (in the straight line order). At the other end, 1 and 3 are called, and 2 and 6 are called.

★Line order at both ends of the crossover lineAs follows:
One end (unchanged) and the other end (two pairs of calls)
Orange white 1 3 green white
Orange 2 6 green
Green white 3 1 orange white
Blue 4 4 blue
Blue white 5 5 blue white
Green 6 2 orange
Brown White 7 brown white
Brown 8 8 Brown

Usage category:
For connection:
1. Host and switch/hub;
2. router and switch/hub

The crossover line is used for connection:
1. Switch and switch;
2. Host and host;
3. Hub and hub;
4. Hub and switch;
5. direct connection between the host and the router

In practice, it is generally understood as follows:
1. Cross-line connections are used between devices of the same type, and direct-line connections are used between devices of different types;
2. vrouters and PCs belong to DTE devices, and vswitches and hubs belong to DCE devices;
3. RJ45 network connection practices generally include 568a and 568b standards. The same standard is the same as the express Connect line, and different standards are the cross lines.
No matter how the wiring, after the completion of the test with a RJ-45 wire meter, the 8 indicators should flash in turn.

 

[The above is taken from "Baidu Knows"]

 

[Additional]:

Straight-through network cable and crossover network cable:

Umg8900 provides LMT operation, maintenance, and management interfaces. Its Fe interface adopts the NIC interface design. Umg8900 uses a straight-through network cable when connecting to MSC server through a hub or LAN switch, and cross-network cable when connecting through direct connection.
When the debug network port provided by the momu board is directly connected to the PC, a crossover network cable is used, and a passthrough network cable is used for connecting to the PC through the hub or LAN switch.

The appearance of the straight-through network cable is the same as that of the Cross network cable, as shown in:

NotesPIN number of RJ45 HeaderAs shown in:

1. passthrough network cable
Shows the connection relationship of the connection cable: 2. crossover network cable
Shows the connection relationship of the crosstab chart: