Rerouting Schemes with Inter-layer Backup Resource Sharing for Differentiated Survivability in IP-over-WDM Optical Networks

This paper addresses the problem of dynamic routing of sub-lambda connections with differentiated survivability using multi-layer protection and inter-layer backup resource sharing in IP/MPLS-over-WDM networks. When providing the differentiated survivability services, mission-critical high priority connections which require optical layer protection are more likely to be rejected than connections which require IP/MPLS layer protection because of the difference in protection granularity. To address this problem, we propose two re routing-based dynamic routing schemes for reducing the blocking of mission-critical connections. In the schemes, rerouting operation is done with the use of lightpaths called potential lightpaths, and an efficient heuristic algorithm is proposed for choosing them. Further, the schemes employ inter-layer backup sharing for the benefit of high priority connections and they adopt strategies which consider critical issues in finding and utilizing the potential lightpaths. Our schemes have several important and attractive features: 1) the schemes do not cause any interruption for ongoing traffic during normal operation, 2) the schemes improve the performance of mission-critical traffic without affecting the performance of other traffic significantly, and 3) the schemes are affordable in terms of computational intensity since the rerouting operation is done only when a mission-critical connection is not honored. Through simulation experiments we investigate the performance of the proposals and verify their effectiveness