Different implementations of token tree algorithm for DWDM network protection/restoration

High-speed optical networks need efficient protection/restoration schemes. A heuristic distributed MST algorithm, called the token tree (TT) algorithm, is proposed in this paper. The TT algorithm consists of four subalgorithms, Namely the upward root selection (URS) algorithm, the star token polling (STP) algorithm, the passive state (PS) algorithm and the active state (AS) algorithm cooperate together to form a logical spanning tree for network protection. Tokens are polled between the PS and AS algorithm and thus decide the node sequence in a spanning tree. The restoration strategy lies in two points: using tree links to protect non-tree links, and seeking a shortest path from a node to its parent in order to protect the corresponding tree link. Performance analysis of the algorithms is performed in some topologies based on existing networks.