A Reconfiguration Algorithm for a Double-Loop Token-Ring Local Area Network

An algorithm to reconfigure a fault-tolerant double-loop token-ring local area network following topological changes is presented. The algorithm guarantees that at all operational times the network is organized to provide maximum possible connectivity among the nodes either one loop that encompasses all nodes in the network or several subloops each of which operates as a separate token ring network. Tokens are generated or eliminated as necessary to result in one and only one token in each (sub)loop. The algorithm is formally specified and its properties are verified.