Quality of Service Guarantees in High Speed Networks A Research Project Funded by the National Science Foundation
Principal Investigator: R. L. Cruz
Summary of Results
- R. L. Cruz, "SCED+: Efficient Management of Quality of Service Guarantees," Technical Report 97-13, Center for Wireless Communications, UCSD, July 1997. Full paper. Abbreviated version to appear in IEEE INFOCOM'98: (118K, gzipped postscript) [ Infocom Slides: ( Postscript, 256K) ( PDF, 74K)]
Current proposals for the provision of deterministic quality of service guarantees in integrated services networks require per-session management of traffic flowing in network switches, raising scalability questions for practical implementation of high speed packet switching in large scale networks. At the same time, the end-to-end delay bounds associated with current proposals can be overly conservative, limiting the utility of the bounds to guide efficient resource allocation. In this paper, we introduce SCED+, a network scheduling algorithm that yields scalable provision of tight deterministic end-to-end delay bounds. These features are acheived through the use of aggregation and by efficient statistical multiplexing between best effort and guaranteed traffic. The SCED+ algorithm also supports statistical multiplexing between "guaranteed" traffic streams, providing tight end-to-end delay bounds for traffic streams which can tolerate non-zero packet loss rates. In order to facilitate the analysis of SCED+, we refine the so-called "network calculus" to address delay jitter, and introduce a simple and unified approach to the analysis of output burstiness of traffic departing a general network element.