As generally used, a concentrator is a device that acts as an efficient forwarder of data transmission signals. A remote access hub is sometimes referred to as a concentrator. The term aggregator is also frequently used with approximately the same meaning. A typical concentrator or remote access hub is a device that handles incoming dial-up calls for an Internet (or other network) point-of-presence and performs other services. A concentrator or hub may be able to handle up to 100 dial-up modem calls, support a certain number of ISDN connections, and support leased line and frame relay traffic while also functioning as a router.
Ascend Communications and U. S. Robotics are leading manufacturers of hubs.