A novel hop constrained sub-path protection routing algorithm in WDM networks

The survivable design is a key issue in reliable WDM optical networks to assure the service guarantee to customers. The sub-path protection metrics can achieve shorter failure recovery time than path protection metrics for a modest sacrifice in resource utilization. Rather than the conventional equal-length sub-path protection metrics (CDR algorithm), in this paper we propose a novel heuristic dynamic hop constrained sub-path protection (HCSPP) routing algorithm to provide a more flexible way to compute the primary sub-paths and the backup sub-paths. The main idea of HCSPP is that we first compute the primary path and its end-to-end backup path, the found primary and its end-to-end backup path constitute a protection cycle, then we partition the protection cycle into several smaller protection cycles by the straddling paths we introduced, the hop count for each small protection cycle should be constrained in a threshold value and the value can be adjusted according to different network topologies or different management policy, thus we can control the tradeoff between the failure recovery time and the resource utilization ratio. Compared with the CDR [P.-H. Ho, J. Tapolcai, T. Cinkler, IEEE/ACM Trans. Networking 12 (6) (2004) 1105] algorithm, HCSPP can achieve a better compromise between the blocking probability and the failure recovery time. We evaluate the effectiveness of the HCSPP and the results are found to be promising.