Performance analysis of VOIP codec schemes and queuing techniques and their impact on FTP and video conferencing.

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Munthali, Emma
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The University of Zambia.
Advancement in internet technology allows for the integration of network traffic i.e data, video and voice into a single network. This technology offers many benefits but also presents some challenges. Real time traffic services such as Voice over Internet Protocol (VoIP) and video require certain Quality of Service (QoS) from the network which cannot be guaranteed on the internet therefore, maintaining the right QoS parameters becomes all the more important. Studies have been carried out on the effect of congestion management tools while others compare the effects of such tools on the quality of VoIP. However, in reality, these tools are not used in isolation in a network and most networks do not support single traffic only. The goal of this research therefore is to compare the effects of the combinations of some of these tools (i.e queuing techniques and codec schemes) on the quality of VoIP and to determine their influence on the rest of the traffic on a network. Simulation approach using the OPNET Modeler 14.5 tool was used to simulate a network supporting three different types of traffic namely: FTP traffic, Video conferencing traffic and VoIP traffic. While maintaining the same topology and traffic of the network, G711 and G729 codec schemes and queuing techniques namely; First in First out (FIFO), Priority Queuing (PQ), Custom Queuing (CQ) and Weighted Fair Queuing (WFQ) were tested resulting in different scenarios. Custom Queuing technique showed the best performance overall except for the amount of video conferencing traffic received where it had the worst performance. WFQ and FIFO suffered the highest delay for video and VoIP traffic respectively while FTP traffic suffered from starvation in PQ. The graphs were observed to follow the same pattern regardless of the codec scheme used however, G729 performed the better of the two as it produced higher throughputs and slightly lower delays compared to G711. G729 would best be used for low bandwidth networks while G711 would be ideal for networks with higher bandwidths and where VoIP communication is the main priority.
Thesis of Master Of Telecommunication Systems.