MAU
Short for Media Access Unit, a MAU is also known as an Ethernet transceiver or MSAU (MultiStation Access Unit) is an adapter, connector, or stand alone device that enables a network device to be connected to a token ring network. A MAU is one form of fault tolerance that helps prevent issues if a network device or computer goes down and are commonly available as either active or passive. An active MAU is not powered and does not in any way strengthen the signal from a device. A passive MAU is powered and repeats and strengthens a signal.
Also see: Ethernet, Network definitions, Token ring