Graph transformation approaches for diverse routing in shared risk resource group (SRRG) failures

Failure resilience is a desired feature of the Internet. Most traditional restoration architectures assume single failure assumption, which is not adequate in present day WDM optical networks. Multiple link failure models, in the form of shared risk link groups (SRLG's) and shared risk node groups (SRNG's) are becoming critical in survivable optical network design. We classify both of these form of failures under a common scenario of shared risk resource groups (SRRG) failures. We develop graph transformation techniques for tolerating multiple failures arising out of shared resource group (SRRG) failures. Diverse routing in such multi-failure scenario essentially necessitates finding out two paths between a source and a destination that are SRRG disjoint. The generalized diverse routing problem has been proved to be NP-Complete. The proposed transformation techniques however provides a polynomial time solution for certain restrictive failure sets. We study how restorability can be achieved for dependent or shared risk link failures and multiple node failures and prove the validity of our approach for different network scenarios. Our proposed technique is capable of improving the diverse route computation by around 20-30% as compared to approaches proposed in the literature.