Controller placement is a key issue for Software Defined wide area network deployment. This issue aims to find the appropriate number of controllers and their location in order to achieve certain performance objectives in the network. These objectives are delay, load-balancing among controllers, reliability, and energy-saving. In this paper, we model the controller placement problem (CPP) as a Facility Location Problem (FLP) to achieve a certain average propagation latency and load-balancing among controllers. In order to model the network, we define three metrics: the average propagation latency between the controllers and data planes; average controller processing latency; average message arrival rate from each data plane. The simulation results reveal that the solution of this optimization location problem could properly find the minimum number of controllers and their appropriate placement in the network to meet the network requirements.