Dynamic Routing and Spectrum Allocation in Elastic Optical Networks with Minimal Disruption

Fragmentation is considered as a major bottleneck for Elastic Optical Networks (EON) resulting in poor spectrum utilization. A defragmentation scheme can be employed to tackle this fragmentation issue. Often defragmentation schemes involve complex procedures and disruption to existing connections. As disruption of connections is paramount for defragmentation schemes in flex-grid EONs, we propose a novel Routing and Spectrum Allocation (RSA) framework in EON that employs controlled disruption for dynamic traffic scenarios. First, we propose a Mixed Integer Linear Program (MILP) model for a sample network which jointly optimizes delay-bandwidth product, fragmentation, and link congestion. Then, a heuristic algorithm for realistic networks is also proposed. We show the benefits of our formulation with existing studies in terms of blocking probability and fragmentation.