Evaluation and design of elastic optical networks resilient to multiple node failures

Consider an existing Elastic Optical Network (EON) with a given topology composed by nodes and connecting fibers, each fiber with a given spectrum capacity. Consider an estimated set of demands to be supported and a routing, modulation and spectrum assignment (RMSA) policy adopted by the operator both for the regular state and for the failure states. First, we address the resilience evaluation of the EON to multiple node failures. We adopt a worst-case approach by identifying the nodes (named critical nodes) whose simultaneous failure maximally reduce the demand percentage that is supported by the network and we use this percentage as the resilience metric. Then, for the same estimated demands, the same RMSA policy and a fiber budget equal to the total fiber length of the existing network, we address the design problem aiming to determine a new EON maximizing the resilience metric imposed by its critical nodes. We use a multi-start greedy randomized method that generates multiple EONs and returns the best one, i.e., the EON with the highest resilience metric. We run the evaluation and design methods on known network topologies. The computational results let us (i) analyze the efficiency of the methods and (ii) assess how far the resilience of existing networks are from the best ones. This paper is based upon work from COST Action CA15127 (”Resilient communication services protecting end-user appli- cations from disaster-based failures – RECODIS”) supported by COST (European Cooperation in Science and Technology). The work was also supported by FCT, Portugal, through project ResNeD CENTRO-01-0145-FEDER-029312 and PhD grant SFRH/BD/132650/2017. Second and third authors were supported by FCT through projects UID/EEA/50008/2019 and UID/MAT/04106/2019, respectively. published