token bus

token bus A form of network (usually a local area network) in which access to the transmission medium is controlled by a token. The network stations (nodes) are interconnected by a bus, i.e. signals are placed on the transmission medium by one station and can be read by all the other stations. If the signal is a token, indicating that the station that was last transmitting has now finished, the token is passed from station to station in a strict sequence. In a token ring this sequence is determined by the order in which stations are physically connected to the transmission medium. A station wishing to transmit will start to do so by removing the token from the bus and replacing it with the data to be transmitted; when transmission is complete, the transmitting station will reinitiate the token passing process.

A token bus system has the advantage that the priority of stations can be redefined by redefining the order in which stations are permitted to acquire the token.