What are the working principles and characteristics of Ethernet switches (how to establish a switching table)?

Take an ordinary layer 2 fool switch as an example, there is only one mac address table.

This table is the binding table of the mac address of the device and the corresponding interface of the switch.

Several messages are described below.

Unknown unicast frame packet, the switch will assign all interfaces except the interface receiving the packet.

Multicast frame, the switch will send out all interfaces except the interface that receives the packet.

Broadcast the frame, and the switch will send out all interfaces except the interface that receives the packet.

According to the corresponding mac address table.

That is to say, only the known unicast frames are the interfaces from which the switch knows that the mac address requested by the data packet can arrive, and it is in the mac address table, so it will be forwarded according to the mac address table. Unknown unicast packet, the switch doesn't know the corresponding switch interface, so broadcast the data, know which interface the mac address corresponds to when receiving the response, and record it by the way. Next time there is data, we will check and forward it.