Fractional switch migration in multi-controller software-defined networking

Abstract Mapping switches to controllers in multi-controller software-defined networking (SDN) is still a hot research topic. Many factors have to be considered when establishing this mapping. Among them are the load balancing and mapping stability. Load balancing is important to improve resources utilization, and mapping stability reduces the control plane overhead created when exchanging information triggered by new mappings. This article presents a model for dynamic switch-controller mapping to achieve load balancing and minimize the number of new switch-controller assignments. To that end, for load balancing, flows from a switch are allowed to be handled by multiple controllers, and to increase assignment stability, the assignments at time t − 1 are taken into consideration when calculating the assignments at time t. The model is formulated as a convex quadratic programming problem, and the properties and feasibility of this model are mathematically analyzed. In addition, a heuristic algorithm is developed to deal with large-scale networks. The experimental results show the effectiveness of the proposed approach when compared to recent academic work, where the proposed model leads to a slight improvement in the load balancing and increases the stability of the switch-controller assignment by  ≈  91%.