A general name for a class of networking devices that extend the distances over which stations (computers) can typically be connected to concentrators such as hubs and switches.
An example is a 10BaseT extender for Ethernet networks. In 10BaseT networks, stations should be located no more than 100 meters from a hub, but by using an extender, you could increase this to about 183 meters.
A 10BaseT extender can thus be used for connecting a remote station, such as a station located in a nearby building, to the network. Extenders are essentially a simplified form of bridge designed to support only a few remote stations.
They need to be installed in pairs, one at the remote location and one at the main network. Some extenders can be used to carry network data over installed phone lines, connecting remote stations without installing additional network cabling.
Graphic E-10. Extender.
Extenders are also available for increasing the maximum connection distance for other data transmission technologies such as the Small Computer System Interface (SCSI) bus.
A normal SCSI bus is limited to about 6 meters, but a fiber-optic SCSI extender can increase this distance to a kilometer or more using duplex fiber-optic cable. You can use parallel extenders for directly connecting to printers located in a different building.
You can use serial extenders to connect computers to remote RS-232 serial test equipment located in laboratories in different buildings.