Augmenting optical topology to improve survivability

In the network design problems the physical network topology is mostly assumed to be two-node-connected, but this is not always true if we consider the aggregation and mobile backhaul segment of real networks. New services demand the survivability fro the whole network. In this paper we present an augmentation method that improves the connectivity of the optical layer by adding new links to the topology. We consider a realistic network topology with design constraints originating in the real world: the map of roads to match and length limits for new links. We give the formal description of a special case of survivability problem and propose some heuristic solutions to augment the topology by moderate cost. The results for a real-size provider network show the importance of the parameters of the constraints that filter out the allowed augmenting links. The influence of the augmentation policy used in the different heuristic gets analyzed too.