An exact optimum paths-finding algorithm for α+1 path protection

Path protection employs a link-disjoint secondary backup path to protect the primary path to ensure continuity of network services. Nevertheless, existing path protection schemes are either less efficient in resource utilization, such as that in dedicated path protection (eg., 1+1 protection) or cannot respond to link failure quickly enough for real-time services, which is prevalent in shared path protection (eg., 1:N protection and M:N protection). Recently, α+1 protection has been proposed to provide partial bandwidth protection for mission critical data only, where α denotes the ratio of protection bandwidth (of secondary path) to the full bandwidth (of primary path). It has been shown that α+1 protection is able to provide fast recovery from link failure with efficient resource utilization. However, finding the optimal pair of primary-secondary paths for α+1 protection remains a challenge. Existing paths-finding algorithm for the α+1 protection utilizes the k-shortest path approach to identify the optimum pair of link-disjoint path through a potential exhaustive search of the prospective solutions. This considerably increases the complexity of the algorithm. In this paper we introduce an exact path-finding algorithm to efficiently obtain the optimum solution for the α+1 protection in polynomial time without utilizing the common k-shortest path algorithm. As such the proposed algorithm is shown to produce the optimum solution while maintaining a low complexity.