Experimental study of desktop videoconferencing in IP internets with QoS

Videoconferencing involves the transmission between the participants of different traffic flows, including such real-time flows as audio and video. In an IP internet without QoS support, the performance of real-time applications can be greatly impacted by network congestion, making them impractical. Recent advances in router technology now make it possible to protect real-time applications from the negative consequences of congestion, permitting the peaceful coexistence on the same internet of real-time and best-effort applications. We present an experimental study of the use of DiffServ technology to protect videoconferencing traffic from the congestion caused by best-effort traffic. The confirmation of the effectiveness of this protection is given by several tests, where we study the performance of point-to-point desktop videoconferencing sessions in the presence of controlled rate cross traffic. The value of the QoS parameters: delay, jitter, packet loss rate and throughput for audio and video media were obtained from the statistical data generated by the RTCP protocol. The results are immediately applicable to the use of desktop videoconferencing service in a corporate network, where this traffic can be transported together with the traditional data applications, since the traffic generated by the former will not disturb the running of the latter, and vice-versa.