A type of
multiplexor that combines multiple
channels onto a single transmission medium in such a way that all the individual channels can be simultaneously active. For example,
ISPs use concentrators to combine their
dial-up modem connections onto faster
T-1 lines that connect to the
Internet.
Concentrators are also used in local-area networks (LANs) to combine transmissions from a cluster of nodes. In this case, the concentrator is often called a hub or MAU.