A Cross Entropy-Based Approach for Controller Placement Problem in Software Defined Network

In order to span across the networks and avoid single point of failure, One grand challenge in the Software Defined Network (SDN) is to select appropriate locations for controllers to shorten the latency between controllers and switches, especially in wide area networks. For this purpose, we formulate the controller placement problem to decrease the communication cost as an integer programming problem. Due to its high computational complexity, we develop a cross entropy based approach to efficiently approximate near-optimal placements. We conduct experiments on 5 real topologies from the Internet Topology Zoo, and the results verify that the proposed approach can realize the minimum propagation latency for different network scales with different number of controllers, with a less than 1% margin from the optimal solution and up to 157 times faster than the brute force.