A media access unit (MAU), also known as a multistation access unit (MAU or MSAU), is a device to attach multiple network stations in a ring topology when the cabling is done in a star topology as a Token Ring network, internally wired to connect the stations into a logical ring (generally passive i.e. non-switched and unmanaged; however managed Token Ring MAUs do exist in the form of CAUs, or Controlled Access Units).[1]
Passive Token Ring was an active IBM networking product in the 1997 time frame, after which it was rapidly displaced by switched networking.