Diverse routing in SRLG networks

Abstract

As our dependency on communication increases so is the demand for protecting these communication lines. To provide failure-safe connections in optical networks, lightpaths can be protected. Protected lightpaths consist of a primary path and a backup path which are disjoint and ensure connection continuity in case of a single link failure. Optical networks consist of at least two layers, the optical layer and the physical layer. And although the primary and backup paths are disjoint in the optical layer, in the physical layer they may share the same fiber span or duct. These links are in the same Shared Risk Link Group (SRLG). If one link of a SRLG fails then all fail. Because of this, a single failure at the physical layer can causes multiple failures at the optical layer and protected paths could get disconnected if both paths have fibers in the broken fiber span. This thesis proposes an exact algorithm which finds the shortest SRLG-disjoint protected path in a network through an iterative approach.