Dynamic RWA algorithms under shared-risk-link-group constraints

In IP over WDM optical networks, there are many traffic flows within every light-path. Failure of one light-path leads to great loss. Therefore, path protection should be provided for every primary light-path, that is, one backup light-path must be provided to the primary light-path. The concept of shared risk link group (SRLG) has been introduced in optical networks, and the primary light-path and the backup light-path are requested to be SRLG-disjoint. We first propose a heuristic algorithm without wavelength assignment. This algorithm can compute two SRLG-disjoint paths simultaneously, and the total cost of the two paths is near optimal. Then, by virtue of a layered-graph, based on the first algorithm, an algorithm for dynamic routing and wavelength assignment (RWA) under SRLG-disjoint constraints is proposed. Analysis of each algorithm is given.