Demonstration of multi-domain spectrum defragmentation with minimum controller-participation degree in elastic optical networks

Spectrum defragmentation in elastic optical networks can be considered to conduct rearrangement of the deployed lightpaths, which can achieve some optimization objectives including lower blocking probability, higher spectrum utilization, minimum connection disruption and so on. The emergence of software-defined networks provides an effective way to implement spectrum defragmentation in control plane. With restricted domain visibility in multi-domain or multivendor scenario, the complex procedure of multi-controller cooperation is inevitable during the multi-domain lightpath provisioning. In this paper, we first introduce the concept of controller-participation degree (CPD) to quantize the times local controllers are involved in multi-domain defragmentation. Then we propose a novel multi-domain defragmentation (MD-DF) scheme with minimum controller-participation degree, which can be categorized as reactive strategy. Based on whether the potential blocked lightpath goes through inter-domain links, the MD-DF scheme covers intra-domain scenario and cross-domain scenario. The proposed scheme is implemented in OpenDayLight (ODL) controller and experimental results validate the overall feasibility. Meanwhile, simulation results indicate that the improved blocking performance is achieved with the MD-DF scheme.