Hub - Network Hub (Concentrator / Repeater Hub)
A Network hub is a device which enables more than one computer (host) to interconnect on a network.
Conventional hubs were used for creating home, office and other networks, but the switching hub (see below) has largely superseded the conventional hub in recent years.
Hub, sometimes referred to as a concentrator or repeater hub, refers to a networking component which acts as a convergence point of a network allowing the transfer of data packets. In its simplest form, a hub works by duplicating the data packets received via one port and making it available to all ports, therefore allowing data sharing between all devices connected to the hub.
A passive hub simply allows the data packets to flow through it, a manageable hub allows the data transfer to be monitored and the ports to be configured individually.
Unlike a standard hub which simply replicates what it receives on one port onto all the other ports, a switching hub keeps a record of the MAC addresses of the devices attached to it.
When the switch receives a data packet, it forwards the packet directly to the recipient device by looking up the MAC address.
A network switch can utilise the full throughput potential of a network's connection for each device making it a natural choice over a standard hub.
In other words, say for instance you had a network of 5 PCs and a server all connected with 10Mbps UTP cable. Using a hub, the throughput (10Mbps) would be shared between each device, with a switch each device could utilise the full 10Mbps connection.
When using a switch instead of a hub it is common place to create a faster throughput connection between the switch and the server (backbone).
For example if you had 10 PCs connected to the switch with 10Mbps cable then it would improve performance to use a 100Mbps connection from the switch to the server.