DDS: Distributed Decision Strategy Based on Switch Migration towards SDN Control Plane

The introduction of distributed control plane has improved the scalability and reliability of software defined networking (SDN), and multi-controller could divide the entire network into several subdomains. However, dynamic traffic could cause uneven load distribution among individual controllers. Furthermore, the static configuration between switch and controller exacerbates this imbalance. Real-time migration of switches from controllers that are overloaded to those that are underutilized could be a solution to deal with the unbalanced distribution of traffic. Therefore, such migration must be performed with a well-defined strategy to fully utilize the available resource of controllers. In this paper, we propose Distribution Decision Strategy (DDS) based on switch migration in the multi-domain SDN network. Firstly, we collect network information and construct distributed migration decision domains based on the load condition of controllers. Then, we choose the migrating switches according to the selection probability, and the target controller is determined by optimizing three network costs, including data collection, switch migration and controller state synchronization. Finally, we set the migrating countdown to ensure the ordered switch migration. Results are demonstrated by several numerical simulations.