One of the important factor for measuring the network performance is bandwidth utilization. In this paper we have evaluated the performance of SDN POX controller in terms of bandwidth utilization. We have used the Mininet as an emulator. The performance of the network is evaluated by using three different scenarios; varying the bandwidth allocated from 10 to 50, increasing the tree topology depth i.e. increasing the number of hosts and switches and by increasing the number of controllers. We have used iperf for measuring the throughput. As a result we can conclude that maximum bandwidth can be utilized for all tree scales if we set the bandwidth to 10. Also we can increase the bandwidth utilization by increasing the number of POX controllers in the network. But increasing number of controllers does not support for large scales. Hence we need to find the optimal number of controllers. 
 
Keywords— SDN, POX controller, bandwidth utilization, mininet, bandwidth utilization