A Novel RSCA Scheme for Offline Survivable SDM-EON With Advance Reservation

In this paper, we have proposed two new Routing, spectrum and core allocation (RSCA) schemes for offline survivable space division multiplexing elastic optical network (SDM-EON) supporting multi-class (mc) traffic in temporal domain. Multipath based protection scheme is applied to ensure survivability against single link failure, thus allowing traffic for each connection to be split amongst those paths. Advanced reservation (AR), being a part of multi-class traffic can withstand some delay from its time of arrival. Two schemes are designed based on the service of AR connections: all the split traffic in the multiple paths for a connection at the source node are set to start (i) at the same time strictly (mc-RSCA-S) and (ii) in a relaxed way by allowing different permissible times (mc-RSCA-R). Mixed integer linear programming (MILP) models are formulated for both the schemes. RSCA problem being an NP-hard one, those MILPs are not tractable and two heuristics with polynomial time complexity are developed. Two heuristics are based on a greedy approach and a simulated annealing (SA) based approach. Simulation studies of MILPs and the respective heuristics confirm that near optimal solutions are obtained by the proposed heuristics in identical experimental setup. It is observed that with an increase in the number of cores as well as in the percentage of AR connections in the incoming request set, spectrum utilization in the network and fragmentation of cores get reduced more by SA based approach compared to greedy approach.