Rhodes University - Department of Computer Science 1 Re-establishing and improving the experimental VoIP link with the University of Namibia: A Case Study ____________________________ Alfredo Terzoli and Mosiuoa Tsietsi Ricky Ngandu

Rhodes University - Department of Computer Science 2 Project Aim/Objective Establish a fully working VoIP link between RU and UNAM

Rhodes University - Department of Computer Science 3 Approach Learn about asterisk and gain practical experience Learn about traffic shaping and test traffic shaping techniques on a network test-bed Learn about UNAM’s network and their ISP SLA Deploy iLanga at UNAM Implement traffic shaping Test the solution

Rhodes University - Department of Computer Science 4 RU – UNAM VoIP Link

Rhodes University - Department of Computer Science 5 Live Network RU has a Kbps Internet connection UNAM has a Kbps Internet connection During working hours there is a high rate of network congestion at UNAM

Rhodes University - Department of Computer Science 6 Network Test-bed Build a network to emulate the existing live network between RU and UNAM Test call quality under normal and congested conditions Implement traffic shaping and test call quality under normal and congested conditions

Rhodes University - Department of Computer Science 7 Results Iperf program was used to measure bandwidth and throughput ManageEngine VQManager was used to analyse VoIP and network traffic Call quality is calculated and rated by MOS (Mean Opinion Score). MOS is described in ITU P.800 MOS rates are between 1 and 5. MOS above 4 are toll quality and those below 3.6 are not satisfactory

Rhodes University - Department of Computer Science 8 Results (cont.)

Rhodes University - Department of Computer Science 9 Results (cont.)

Rhodes University - Department of Computer Science 10 Deployment Challenges Geographic separation makes it challenging to streamline VoIP deployment between UNAM and RU UNAM uses a Telecom owned ISP and their bureaucracy has stalled deployment due to blocked VoIP ports Low bandwidth was a major headache during installation and testing

Rhodes University - Department of Computer Science 11 Challenge Solutions To resolve the technical and bureacracy surrounding VoIP we opted to use two test sites UNAM and Polytechnic of Namibia (PoN) We opted for IAX over SIP to bridge the two PBXs. This is due to security restrictions, codec limitations and a NAT-ed network Speex codec works best over IAX between the sites. Speex compresses between 2 – 44Kbps

Rhodes University - Department of Computer Science 12 Conclusion Traffic shaping improves the quality of voice calls over congested networks IAX is better to use over congested and NAT-ed networks for audio but not video because there has been a slow development for video handling SIP is better to use for video but is difficult to run over NAT-ed networks

Rhodes University - Department of Computer Science 13 Future work Although SIP is more widely used than IAX, SIP does not handle NAT-ed networks well. Develop clients and codecs that handle video over IAX Improve SIP to handle NAT-ed networks better

Rhodes University - Department of Computer Science 14 Questions?