Abstract

The advent and deployment of IP Multicast has fueled the growth of multi-user collaborative applications. The MBone, the Internet multicast infrastructure, extends the traditional best-effort unicast delivery model of the Internet to enable efficient multipoint packet delivery. Using IP Multicast to deliver archived multimedia content can provide significant advantages in scalability and efficiency. With the popularity of collaboration tools for audio/video conferencing on the MBone, we have seen a number of applications developed to record and play back these MBone sessions. In this paper, we look at the requirements for an archive system control protocol that allows the initiation and manipulation of a playback session. We present a control protocol which itself uses IP multicast. This provides benefits in scalability, fault recovery, and allows simultaneous control of an archive session by multiple clients. The interesting features of our protocol include the application of soft server state techniques, and a built-in mechanism for fault detection and recovery. We have implemented and deployed a prototype and are actively using it in our research group.

Citations