QoS evaluation of a voice over IP network with video: A case study

In this paper, we evaluate the effect of different queueing disciplines and different codecs on a voice over IP (VoIP) network with video (also known as video conference). A real network topology is implemented using Cisco equipment. Experimental results show that low latency queueing (LLQ) and AutoQoS can provide significant improvements over FIFO in terms of delay, jitter and reserved bandwidth for a VoIP call with video. As far as codecs are concerned, they are suitable for different scenarios. It's for certain that G.729 helps when low bandwidth is a must but, without any QoS parameters in place, codecs do not make a good enough difference for acceptable call quality on a congested network.