Design of multi-granularity directed segment p-cycles

In today optical WDM networks, capacity expansion is performed by the addition of transport blades (e.g., transceivers) at end nodes of optical fibers. It allows the multiplexing of optical channels (wavelengths) with different granularities. In this paper, we propose a new ILP-based design approach of survivable WDM multi-granularity segment p-cycle where the objective is to minimize the cost of spare equipment at switching nodes in order to provide 100% single link failure protection. We use column generation (CG) optimization techniques, an efficient large scale optimization tool, in order to integrate, in an on-line fashion, the p-cycles generated during the optimization process. We, therefore, avoid a time and space costly prior enumeration of the candidate p-cycles. Extensive experiments are conducted to compare the proposed nodal equipment cost optimized design of segment p-cycles with the classical link spare capacity optimization approach. Numerical results show that the protection design corresponding to spare node equipment optimization is more effective than the one based on link spare capacity.