Ahmad Jalili - Shiraz University of Technology, Department of Computer Engineering & IT, Shiraz, Iran./
Vahid Ahmadi - Shiraz University of Technology, Department of Mathematics, Shiraz, Iran.
Manijeh Keshtgari - Shiraz University of Technology, Department of Computer Engineering & IT, Shiraz, Iran.
Morteza Kazemi - Shiraz University of Technology, Department of Industrial Engineering, Shiraz, Iran.

SDN is a promising architecture that can overcome the challenges facing traditional networks. SDN enables administrator/operator to build a simpler, customizable, programmable, and manageable network. In software-defined WAN deployments, multiple controllers are often needed, and the location of these controllers affects various metrics. Since these metrics conflict each other, this problem can be regarded as a multi-objective combinatorial optimization problem (MOCO). A particular efficient method to solve a typical MOCO, which is used in the relevant literature, is to find the actual Pareto frontier first and give it to the decision maker to select the most appropriate solution(s). In small and medium sized combinatorial problems, evaluating the whole search space and finding the exact Pareto frontier may be possible in a reasonable time. However, for large scale problems whose search spaces involve thousands of millions of solutions, the exhaustive evaluation needs a considerable amount of computational efforts and memory used. To address this problem, heuristic methods are very effective for estimating the original Pareto frontier within a relatively small algorithm’s runtime and memory. In this paper, we adapt the efficient algorithm NSGA-II for solving a new presented multi-objective model of the control placement problem [7]. The results of implementing the adapted algorithm carried out on the Internet2 OS3E network run on MATLAB 2013b confirmed its effectiveness.

Multi-objective Combiatorial Optimization, Pareto frontier, SDN, Controoler Placement Problem, NSGA-II