How does a switch in a switched LAN work?

The working principle is: multiple concurrent connections are established between its multiple ports. The Layer 2 switching of the LAN switch performs the bridging function and forwards data according to the MAC address. The switching speed is fast, but the control function is weak. , no routing function. Layer 3 switching forwards data based on IP addresses and has routing functions.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

Basic working principle: The core device of the switched LAN is the LAN switch. The LAN switch can establish multiple concurrent connections between its multiple ports. The Layer 2 switching of the LAN switch performs the bridging function. According to The MAC address forwards data and has fast switching speed, but the control function is weak and there is no routing function. Layer 3 switching forwards data based on IP addresses and has routing functions.

Low switching latency is the main feature of LAN switches. From the perspective of the magnitude of transmission delay, if the switch is tens of microseconds, the bridge is hundreds of microseconds, and the router is thousands of microseconds; supports different transmission rates and working modes; high transmission bandwidth; supports virtual LAN services . Switched LAN is the basis of virtual LAN, and current switches basically only support virtual LAN.

Extended information:

The internal structure of the switch

1. Shared memory structure, this method Easy to implement, but requires a large memory capacity and high management costs. And since it takes time to access the memory, it is impossible to achieve line-speed switching between a large number of ports, so it is more suitable for small system switches.

2. Cross bus structure. This structure is suitable for single-point transmission, but there are certain problems for multi-point transmission.

3. The hybrid cross bus structure divides the integrated cross bus matrix into small cross matrixes and connects them through a high-performance bus in the middle. The advantage is that it reduces the number of cross buses, reduces costs, and reduces bus contention.

4. Ring bus structure, used to collect bus status, process routing, flow control and clean up the data bus. The biggest advantage of the ring bus structure is its strong scalability and low cost. Because of the ring structure, it is easy to aggregate bandwidth. When the number of ports increases, the bandwidth increases accordingly.

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