Deterministic Delay Bounds for VBR Video in Packet-Switching Networks: Fundamental Limits and Practical Tradeo s

|Compressed digital video is one of the most important tra c types in future integrated services networks. However, a network service that supports delay-sensitive video imposes many problems since compressed video sources are variable bit rate (VBR) with a high degree of burstiness. In this paper, we consider a network service that can provide deterministic guarantees on the minimum throughput and the maximum delay of VBR video tra c. A common belief is that due to the burstiness of VBR tra c, such a service will not be e cient and will necessarily result in low network utilization. We investigate the fundamental limits and tradeo s in providing deterministic performance guarantees to video and use a set of 10 to 30 minute long MPEG-compressed video traces for evaluation. Contrary to conventional wisdom, we are able to show that, in many cases, a deterministic service can be provided to video tra c while maintaining a reasonable level of network utilization. We rst consider an ideal network environment that employs the most accurate deterministic, time-invariant video tra c characterizations, the optimal Earliest-Deadline-First packet schedulers, and exact admission control conditions. The utilization achievable in this situation provides the fundamental limits of a deterministic service. We then investigate the utilization limits in a network environment that takes into account practical constraints, such as the need for simple and e cient policing mechanisms, packet scheduling algorithms, and admission control tests.