Joint Placement Latency Optimization of the Control Plane

Software Defined Networking (SDN) is a programmable network architecture that decouples the control plane (controller logic) from the data plane (forwarding plane) and provides flexible network management. A logically centralized control plane supports SDN feasibility. A single controller may not be capable to control the whole network. To tackle this issue, deploying multiple controllers are a necessity to handle a large network. Controller placement problem (CPP) is one of the most important issues in SDN to improve the scalability and influences the latency and performance of the whole network. Most of the previous methods only focused on latency between controllers and their associated switches but ignoring the latency between controllers and the accumulated latency of the control plane.In this paper, we define an accumulated latency to solve CPP, which takes into consideration both the latency between the controller and their associated switches and inter-controller latency. We formulate an optimization problem as a mixed-integer linear programming (MILP) under the constraint of latency. The objective of our study is to minimize the accumulated latency and minimizing the number of network controllers while optimizing their placement for achieving an optimal balance at the same time. The performance of our method is evaluated on the Internet2 OS3E real network topology. Results demonstrate that the proposed method is promising.