Candidate cycles generation for p-cycle calculation considering SRLGs

A p-cycle is a ring-like structure, capable of protecting links in the ring and also links with both end nodes in the ring. Protection schemes using p-cycles have the speed of ring protection approaches and the capacity efficiency of mesh-based approaches. The spare capacity of the network is pre-allocated to the selected p-cycles. One of the key issues in p-cycle network design is the selection of the candidate cycles. Several variants are proposed for a previously known algorithm for candidate cycles generation. In particular an expansion procedure, for generating new longer candidate cycles, using previously calculated basic cycles, is presented. The recovery speed of p-cycles may be compromised if the recovery cycle depends on the failed SRLG. An algorithm is proposed for calculating SRLG-independent candidate cycles which also benefits from the previous expansion procedure. Simulation results show that one of the modifications together with the expansion mechanism can significantly improve the required spare capacity, without compromising the CPU time for obtaining a solution. Also, the new algorithm for calculating a set of SRLG-independent p-cycles, obtains an adequate set of candidate cycles in a short time.