Improving Quality of Service for Voice-Over-IP Using Routing Diversity

Transmitting voice over the Internet, especially over long distances, is hampered by difference in available network resources at different locations over the world. For Instance, VoIP (voice over Internet protocol) services perform much better at locations having high-speed broadband network than locations with limited bandwidth. In this study, the effect of distance between communicating nodes and usage of diverse routes on QoS (quality of service) is studied for VoIP. RTP over UDP is used to transmit voice. RTCP provides feedback about delay, packet-loss and jitter. Routing diversity is implemented using NISTNet, an emulator. The statistics collected from the tests indicate that packet loss rate, delay and jitter are significantly affected by the distance between end nodes. In addition, results show that voice quality can be significantly increased for long distance links, where packet loss is high, by using routing diversity than just sending all the packets through one path