Effective algorithms for finding optimum pairs of link-disjoint paths in α+1 path protection

Path protection ensures continuity of network services against link failure by assigning a link-disjoint secondary path to protect the primary path. Existing path protection schemes are classified into dedicated- and shared-path protections. However, these schemes either require high redundancy or substantial response time to resolve link failure. The end-to-end partial bandwidth protection scheme, denoted as alpha+1 protection, offers an alternative where only critical real-time information of the primary path is duplicated over the secondary path. The parameter alpha is defined as the ratio of the protection bandwidth (of secondary path) to the full bandwidth (of primary path). The challenge of alpha+1 protection is to identify a pair of primary-secondary paths with lowest total cost comprising the optimal solution. This paper derives the properties inherent in the optimal solution and subsequently presents two optimum paths-finding algorithms. The performance of the proposed algorithms over existing approaches is then compared through simulation.