Achieving resource reduction for protecting multicast sessions in WDM mesh networks

The advances in wavelength division multiplexing (WDM) technology are expected to facilitate bandwidth-intensive multicast application by establishing a light-tree, which regards the source node as the root, and involves all the destination nodes. The light-tree is sensitive to failures, e.g., a single fiber cut may disrupt the transmission of information to several destination nodes. Thus, it is imperative to protect multicast sessions. In this work, we investigate the problem of protecting dynamic multicast sessions in mesh WDM networks against single link failures. Our objectives are to minimize the usage of network resources in terms of wavelength links for provisioning survivable multicast session, and to reduce the multicast session blocking probability. We propose two efficient multicast session protecting algorithms, called Optimal Path Pair based Removing Residual Links (OPP-RRL) and Source Leaf Path based Avoiding Residual Links (SLP-ARL), which try to reduce the usage of network resource by removing or avoiding residual links in the topology consisting of light-tree and its backup paths. To evaluate the proposed algorithms, we apply Integer Linear Programming (ILP) to generate an optimal solution. We also compare the proposed algorithms with existing algorithms through simulation. Simulation results indicate that the two proposed algorithms have better performance than other existing algorithms in terms of wavelength links required and network blocking probability. Furthermore, the solutions generated by the two proposed algorithms are quite close to the solutions generated by ILP in terms of the number of wavelength links required, when the network size is small.