COMMUNICATIONS NETWORK SYSTEM AND METHOD FOR ROUTING BASED ON DISJOINT PAIRS OF PATHS

Methods for determining at least two pre-computed paths to a destination in a communications network are provided. The two paths are maximally disjoint. Maximally disjoint paths are paths where the number of links or nodes common to the two paths is minimized. This minimization is given a priority over other path considerations, such as bandwidth or cost metrics. By pre-computing a maximally disjoint pair of paths, the probability that an inoperable link or node is in both paths is minimized. The probability that the inoperable link or node blocks a transfer of data is minimized. Additionally, a pair of maximally disjoint paths is determined even if absolutely disjoint paths are not possible. The communications network may include at least four nodes, and maximally disjoint pairs of paths are pre-computed from each node to each other node. A third path from each node to each other node may also be computed as a function of bandwidth or a cost metric. Therefore, the advantages of the maximally disjoint pair of paths are provided as discussed above and a path associated with a higher bandwidth or lower cost is provided to more likely satisfy the user requirements of a data transfer.