A spectrum allocation scheme based on first-last-exact fit policy for elastic optical networks
This paper evaluates the performances of elastic optical networks (EONs) in terms of request blocking probability with and without incorporation of spectrum conversions at intermediate switches. In EONs, dynamically setting up and tearing down of lightpath connections generate spectrum fragmentation problems. The spectrum fragmentation problem occurs when the available spectrum slots are isolated from each other as neither they are aligned along the routing path nor they are contiguous in the spectrum domain. The spectrum conversion at intermediate switches is performed for blocked requests without triggering any defragmentation process. Simulation results indicate that the incorporation of spectrum conversions significantly suppresses the request blocking probability and increases the traffic admissibility when the traffic load is low. In a congested network under heavy traffic load, the performance is comparable with and without incorporation of spectrum conversion.