Protecting a multicast session against single link failures in a mesh network

In this report, we investigate approaches and algorithms for establishing a multicast session in a mesh network while protecting the session against any single link failure, e.g., a fiber cut in an optical network. We propose two new and efficient approaches for protecting a multicast session: 1) segment protection in which we protect each segment in the primary tree separately (rather than the entire tree) and allow these backup segments to share arcs with the other existing primary and backup segments; and 2) path-pair protection in which we protect a path between each source-destination pair by finding a disjoint backup path. Unlike previous schemes such as finding link-disjoint trees and arc-disjoint trees, our new schemes 1) guarantee a solution where previous schemes fail and 2) find efficient solution requiring less network resources. Our algorithm, based on the path-pair protection scheme, called optimal path-pair-based shared disjoint paths (OPP-SDP) algorithm, finds a solution if such a solution exists and outperforms all the other schemes in terms of network cost. We also show that OPP-SDP performs close to the optimal solution obtained by solving a mathematical formulation of the problem expressed as an integer linear program (ILP).