The Controller Placement of Software-Defined Networks Based on Minimum Delay and Load Balancing

Software Defined Network (SDN) separates control plane from data plane, and uses multiple controllers to resolve the extensibility and security of SDN. However, most research concentrates on the control layer architecture, ignoring the controllers placement problem. In this paper, we first define the total flow request cost that considers switch weights, switch-tocontroller routing costs, and inter-controller routing costs. Next, we propose controller-based load balance factor, with a known number of controllers, the position of the specific controllers is derived by minimizing the linear function of the load balance factor and the total flow request cost. Finally, through simulation, the controller layout scheme reduces the flow request cost of the SDN and achieves load balancing among the controllers.