Directed p-cycle protection in dynamic WDM networks

p-Cycle protection is an efficient pre-configured and pre-cross-connected protection scheme which can achieve ring-like recovery speed while retaining the capacity efficiency of mesh-based schemes. Thereafter, we study the stability and the efficient reconfiguration of p-cycles in the context of dynamic asymmetric traffic, a protection problem that is acknowledged to be difficult to solve, but with which we must deal in the context of intelligent optical networks (IONs). While most studies have focused on static traffic, the few studies with a dynamic traffic assumption reports the necessity to use heuristics instead of Integer Linear Programming (ILP) tools because they are too time consuming. We claim that assuming appropriate ILP tools are used, such tools are scalable. We investigate three p-cycle updating strategies. We design and solve exact models for each strategy, using large scale optimization tools. Results show that, not only the proposed ILP tools are scalable, but in addition, that, by modifying only a very small fraction of the already established p-cycles, we get a protection level that is as good as if we would reset the whole set of p-cycles.