The main function of the 1. hub is to regenerate, shape and amplify the received signal, thus expanding the transmission distance of the network, and at the same time concentrating all nodes on the node centered on it.

2. It works in the first layer of the OSI reference model, that is, the "physical layer". Hub, like network card, network cable and other transmission media, belongs to the basic equipment in LAN.

3.HUB hub belongs to the bottom equipment of pure hardware network, and basically does not have the ability of "intelligent memory" and "learning" similar to switches. It also has no MAC address table owned by the switch, so it sends data by broadcast, not as a target. That is, when it wants to send data to a node, it does not send data directly to the destination node, but sends data packets to all nodes connected to the hub.