A Fault-Tolerant Multipoint Cycle Routing Algorithm (MCRA)

In this paper we propose a new efficient fault tolerant multipoint routing algorithm for optical networks. The routing for a multipoint request is accomplished by finding a bidirectional cycle simple or nonsimple including all nodes that are participating in the multipoint session. Each link can be used only once. Use of a cycle ensures that a single link (or node in case of simple cycle) failure does not interrupt the session except the failed node if it was part of the multipoint session. Determining the smallest cycle with a given set of Multi-point (MP) nodes is a NP-Complete problem. Therefore, we explore heuristic algorithms to determine an appropriate cycle to route multipoint connections. We allow non-simple cycles to route requests as they use fewer resources than simple cycles in some cases. We also provide an ILP formulation for routing multipoint request and compare its results with the output of our best heuristic algorithm. On Arpanet for over 80% of the time, our best heuristic is able to find a cycle that is within 1.2 times that of the optimal