Short for Media Access Unit, an MAU is also known as an Ethernet transceiver or MSAU (MultiStation Access Unit). MAU is an adapter, connector, or stand alone device that enables a network device to be connected to a token ring network. An 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. A passive MAU is not powered and does not in any way strengthen the signal from a device. An active MAU is powered and repeats and strengthens a signal.