Function: It is to expand the network transmission distance and regenerate the signal by retransmitting or forwarding the data signal (that is, to amplify and shape the original signal). Principle: Repeater is a device connecting network lines, which is often used for two-way forwarding of physical signals between two network nodes. Repeater is the simplest network interconnection equipment, which mainly completes the function of physical layer, and is responsible for transmitting information bit by bit on the physical layer of two nodes, and completing the functions of signal replication, adjustment and amplification, thus prolonging the length of the network.

It's actually a switch. In the past, it was a hub. Its only function is to amplify the signal and extend the transmission distance, but the limit is four, not much.