Performance analysis of the deadline priority path rereservation protocol in a multimedia virtual path crossconnect network

The statistical multiplexing gain of the path rereservation protocol in a star ATM network is evaluated. The transport of large data packets from media servers (MS) to users is scheduled by the multitoken exchange (MTEX) protocol which provides real time guarantees for the delivery of data and prevents collisions. We study the performance of the MTEX protocol when the network traffic is generated by user interactive requests. These traffic requirements may arise in interactive applications such as games, home shopping, etc. The time between successive data requests by one user is assumed to be exponentially distributed. Every data request is submitted with a soft or a hard time deadline. The performance of the path reservation protocol is evaluated in terms of the task response time and the probability of missed deadlines. We show that a high statistical multiplexing gain which is a function of the required task response time is achievable in the case of interactive multimedia information retrieval applications. Empirical relationships that may be used by the media servers to maximize the efficiency are proposed. They are based on the number of active users, the average time between successive data requests, and network design parameters