QoS Improvement of VoIP over SDN

Abstract

Due to the advances of VoIP services such as Skype and Line, people are able to make conversation over the Internet with very low cost. However, VoIP is a real-time application and large end-to-end delay may cause poor communication quality. Most existing mechanisms to improve VoIP QoS are based on the traffic classes, but various voice traffic flows may experience different delays due to different end-to-end distances, and hence various number of intermediate hops which cause variation of delay. In this paper, we propose a novel mechanism that assigns different VoIP flows into different queues based on the path selection by SDN. Usually the biggest variable delay in IP voice communication systems is the queuing delay introduced by switches or routers along the path, and the queuing delay is influenced by the link utilization. Thus, we use hop-count and link utilization to determine which queue the incoming VoIP flows should go through. To ease the task of calculating hop-count of flows and link utilization in the intermediate nodes, we use software-defined network (SDN) to perform the task of routing path selection. The simulation results show that our proposed mechanism can improve QoS of VoIP significantly.