Dynamic establishment of restorable connections using p-cycle protection in WDM networks

Dynamic establishment of restorable connections in WDM networks is an important problem that has received much study. Existing algorithms use either path-based method or link-based method to protect a dynamic connection; the former suffers slow restoration speed while the latter requires complicated online backup path computation. In this paper, we propose a new dynamic restorable connection establishment scheme using p-cycle protection. For a given connection request our scheme first computes a working path and then computes a set of p-cycles to protect the links on the working path so that the connection can survive any single link failure. The key advantage of the proposed scheme over the link-based method is that it enables faster failure recovery while requiring much simpler online computation during connection provision. Our scheme consists of three components: offline computation of primary p-cycles, online computation of the working path, and online computation of p-cycles for working path protection. We adopted two existing algorithms, called SLA and Grow, for the first component and proposed two algorithms, called PS and PNS, for the second component. Simulation study shows that Grow combined with PNS gives the best performance in terms of the total capacity consumed for a given set of demands.