Dual-failure restorability analysis of span-restorable meta-mesh networks.

The span-restorable meta-mesh model was previously designed as a cutting-edge technique that enhanced the spare capacity efficiency in low average nodal degree networks. In this technique, lightpaths that fully traverse chains of degree-2 nodes are provided with a logical express bypass span allowing a distinction between the internal and external working flow capacity that transit the chain. In the event of span failure, lightpaths which would normally traverse the chain in its entirety are allowed to fail back to its anchor nodes such that only the intrachain flow requires allocation of spare capacity. Previous work on the meta-mesh design considered only single failure restorability. The work herein analyzes dual span failure situations by developing two new integer linear programming models. The first model provides the minimum total cost of designing a meta-mesh network capable of withstanding dual span failure scenarios. The second model offers a maximization of the dual failure restorability by minimizing the number of nonrestored working capacities with a given limit of total spare capacity investment. Experiments are performed on six master test-case networks of various topologies and scales.