In this paper, we present an Openflow-SDN based network visualization and performance evaluation model that helps in network designing and planning to examine how networks' performance will be affected as the traffic loads and network utilization change. To achieve the aimed goal, as a research method, we used AnyLogic Multimethod simulation tool. This is a first of its kind where SDN performance evaluation is based on queuing model simulation to monitor change of average packet processing time for various network parameters. Using presented in this work SDN model, network administrators and planners can better predict likely performance changes arising from traffic variation. This allows them to make prompt decisions to prevent seemingly small issues from becoming major bottlenecks.