A hub is an element of hardware for centralising network traffic coming from multiple hosts, and to propagate the signal. The hub has a certain number of ports (it has enough ports to link machines to one another, usually 4, 8, 16 or 32). Its only goal is to recover binary data coming into a port and send it to all the other ports. As with a repeater, a hub operates on layer 1 of the OSI model, which is why it is sometimes called a multiport repeater.
The hub connects several machines together, sometimes arranged in a star shape, which gives it its name, due to the fact that all communication coming from the machines on the network passes through it.
There are several categories of hubs:
It is possible to connect several hubs together in order to centralise a larger number of machines; this is sometimes called a daisy chain. To do this, all that is needed is to connect the hubs using crossover cable, a kind of cable which links the in/out ports on one end to those on the other.
Hubs generally have a special port called an "uplink" for connecting two hubs together using a patch cable. There are also hubs which can cross or uncross their ports automatically depending on whether they are connected to a host or a hub.
|Up to three hubs can be chained.|
If you want to connect multiple machines to your Internet connection, a hub is not enough. You'll either need to have a router or a switch, or to leave the computer connected directly as a gateway (it will stay on constantly for as long as the other computers on the network want to access the Internet.)