Failure-Based Controller Placement in Software Defined Networks

Software Defined Networking (SDN) takes out the control plane of the network elements and distributes it to separate entities named as controllers. The main aim of the Controller Placement Problem (CPP) is to compute the optimum locations for controller deployment and assignment of switches to respective controllers. Every controller failure results in disconnection of switches from the controller leading to reassignment of switches to one or more of the active controllers. In this paper, we propose a controller placement strategy for multiple link failures, considering the network properties, to minimize the worst case latencies. We propose the solution using decision making under uncertainty (and non-competitive situations). Our objective is to find the optimum positions in the network for controller placement with reduced Maximum Worst Case Latency (MWCL) and maximum utilization of the controller. In addition, we have proposed the constraint-based solution for reassignment of switches to active controllers in the network. We have evaluated the proposed methodologies on various network topologies from Internet Topology Zoo. It is found that the decision making under uncertainty provides a better solution on CPP as compared to the existing mathematical methods for any SDN network topology.