mmdump: A tool for monitoring Internet multimedia traffic

Internet multimedia traffic is increasing as applications like streaming me dia and packet telephony grow in popularity. It is important to monitor the volume and characteristics of this traffic, particularly because its behav ior in the face of network congestion differs from that of the currently do minant TCP traffic. To monitor traffic on a high-speed link for extended pe riods, it is not practical to blindly capture all packets that traverse the link. We present mmdump, a tool that parses messages from RTSP, H.323 and similar multimedia session control protocols to set up and tear down packet filters as needed to gather traces of multimedia sessions. Unlike tcpdump, dynamic packet filters are necessary because these protocols dynamically n egotiate TCP and UDP port numbers to carry the media content. Our tool capt ures only packets of interest for optional storage and further analysis, th us greatly reducing resource requirements. This paper presents the design a nd implementation of mmdump and demonstrates its utility in monitoring live RTSP and H.323 traffic on a commercial IP network. The preliminary results obtained from these measurements are presented.