Like Ethernet, Token Ring is a LAN technology that provides shared media access to many connected hosts.
Token Ring hosts are arranged using the ring topology. A token is passed from host to host around the ring,
giving the current token holder permission to transmit a frame onto the ring. Once the frame is sent, it is
passed around the ring until it is received again by the source. The sending host is responsible for removing
the frame from the ring and for introducing a new token to the next neighboring host. This means that only
one station can transmit at a given time, and prevents a Token Ring network experiencing collisions.
A Token Ring network offers a bandwidth of 4 Mbps or 16 Mbps. At the higher rate, hosts are allowed to
introduce a new token as soon as they finish transmitting a frame. This early token release increases
efficiency by letting more than one host transmit a frame during the original token's round trip. One station
is elected to be the ring monitor, to provide recovery from runaway frames or tokens. The ring monitor will
remove frames that have circled the ring once, if no other station removes them.
Traditional Token Ring networks use multistation access units (MSAUs) to provide connectivity between
hosts. MSAUs have several ports that a host can connect to, with either a B connector for Type 2 cabling or
an RJ-45 connector for Category 5 UTP cabling. Internally, the MSAU provides host-to-host connections to
form a ring segment. The Ring-In and Ring-Out connectors of a MSAU can be chained to other MSAUs to
form a complete ring topology.