Maximizing restorability of hierarchical P-tree in survivable mesh networks

This paper presents a study on optimization of hierarchical protection trees (p-trees) for maximum restorability in a survivable mesh network with fixed working and protection capacities on network links. Hierarchical p-trees provide a link restoration mechanism in mesh networks by assigning primary and backup parent nodes for each node in the network. Any link failure in the network will be re-routed through the hierarchical spanning tree, and a failure in the tree itself will be recovered by switching the downstream node on the failed link to its backup parent node. We formulate the restorability optimization problem for the case where the working and protection capacities of the network are fixed, and the objective is to find a p-tree that maximizes restorability using the available protection capacity in the network. We present a heuristic algorithm to design the p-tree in conformity with the constraints of the optimization problem. We use simulation results with random and real networks to study the impact of various network parameters on restorability and to compare our results with other link restoration schemes.