An Ethernet hub is a piece of hardware that connects multiple computers or devices in order to form a network. An Ethernet hub is outdated and has been replaced by a network switch. There are still some special cases where a hub is advantageous to a switch, although none of the reasons to use a hub instead of a switch pertain to a typical network.
An Ethernet hub usually uses the RJ-45 connector on an Ethernet CAT5 cable, although they can also use other legacy (old) connectors. You don’t need to worry about specifics because the typical network cable is a CAT5 with an RJ-45 connector. Simply plug one end of the Ethernet cable into the Ethernet port of your computer and the other end of the cable into the Ethernet port of the hub.
An Ethernet hub typically has 4 or 5 Ethernet ports. But you can also find Ethernet hubs with 6, 8, or 16 Ethernet ports. You can also connect an Ethernet hub to other hubs, routers, and switches.
A hub is a relatively simple device. A hub receives a signal from a computer on the network and re-broadcasts that signal to all other computers and components attached to the hub. Because all signals sent to the router are rebroadcast to all ports on the router you have the potential for a data collision. This is where a computer is trying to send an outgoing signal during an incoming signal.
A hub is able to detect data collisions on the network and then broadcast a jam signal to all ports on the network. Due to these data collisions the number of hubs attached to one another is limited. For a 10 megabit a second network speed you can attach up to 4 hubs to each other and only 2 hubs can be connected for a 100 megabit a second network speed.
In addition to detecting collisions some hubs are able to troubleshoot network problems. These hubs can detect if a particular port has excessive collisions or jabbering. Advanced hubs are able to disconnect these bad ports from the rest of the hub.
When using a hub the speed of the network is limited by the slowest device connected to the hub. For example if an old computer with a 10 megabit per second network adapter is connected to a 10/100 megabit per second hub the entire network’s speed will be 10 megabits per second. Dual speed hubs overcome this problem and function at 10 and 100 megabits per second.
Hubs have been replaced by switches. A switch is more efficient than a hub because it sends information solely to the computer it is intended for and not to every device connected to the switch.