A hub is a machine that brings network cables together, a connector for multiple hosts and devices. The main function of the hub is to extend the transmission distance of the network. It is a form of repeater. The difference lies in that the hub can provide multi-port service, also known as multi-port repeater. The hub is at the OSI/RM physical layer.
The basic function of a hub is information distribution, which distributes all signals received by one port to all ports. Some hubs regenerate weak signals before distribution, and some clean up the timing of signals to provide synchronous data communication across all ports.
A hub is essentially a multi-port repeater. Hubs generally have 4, 8, 16, 24, 32 and other numbers of RJ45 interfaces, through these interfaces, the hub will be able to complete the corresponding number of computers "relay" function (has been the attenuation of incomplete signal after sorting, to produce a complete signal to continue transmission). Because of its "central" position in the network, a HUB is also called a "HUB."
The hub works in a simple way, such as having a hub with eight ports for connecting eight computers. The hub is located in the "center" of the network, through which signals are forwarded and eight computers can be connected to each other. The specific communication process is as follows: If computer 1 to 8, a message sent to the computer when a computer network card through the information 1 twisted pair to the hub, hub will not directly send information to the computer 8, "broadcast" - it will information and send the information to the eight ports, when eight port on the computer to receive the broadcast information, will check the information, If you find that the message is sent to you, you receive it. Otherwise, you ignore it. Since the message is sent from Computer 1 to computer 8, eventually computer 8 will receive the message, while the other seven computers will read the message and reject it because it is not their own.