CAREER: Integrated Traffic Management Based on Accurate and Practical Packet Fair Queueing Algorithms

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Multiple network services include guaranteed real-time service, predicted real-time service, and best-effort service. While there has been extensive research on designing traffic management algorithms for each individual service, it is unclear how these algorithms can be integrated into one network and how they will interact with each other. This problem becomes more complex when the network also needs to support link-sharing, which allows resource sharing among applications that require different network services but belong to the same administrative class. The service disciplines at the switching nodes, which determine the order in which packets are serviced, play a critical role in controlling the interactions among different traffic streams, different service classes, and different link sharing classes. The hypothetical Fluid Fair Queueing (FFQ) discipline, which can serve multiple traffic streams simultaneously according to pre-specified service shares, provides an ideal framework to integrate traffic management algorithms for different services and link sharing. Since FFQ uses an idealized fluid model that cannot be implemented in the real-world, Packet Fair Queueing (PFQ) algorithms are needed to approximate its behavior. Previously proposed PFQ algorithms including the most popular Weighted Fair Queueing all introduce substantial inaccuracy in approximating FFQ, which significantly affects traffic management and link sharing algorithms. It is unclear whether accurate PFQ's exist, and if they do, whether they can be simple enough to be implementable at high speed. The goal of this research is to demonstrate that accurate and practical PFQ algorithms can be designed and that they provide the foundation for a framework under which traffic management algorithms for different services and link sharing can be supported in an integrated fashion. Aspects treated include (a) the fundamental tradeoff between complexity and accuracy of PFQ algorithms; (b) issues in integrating different traffic management algorithms and link-sharing into one framework and fundamental tradeoffs between accuracy of PFQ algorithms and the efficiency of link-sharing and traffic management algorithms; (d) admission control algorithms for providing end-to-end performance guarantees using PFQ algorithms under not only rate-proportional but also general resource assignments; e) more flexible real-time services such as renegotiated service and rate-adaptive service based on PFQ algorithms. The study is conducted via a combination of analysis, simulation, and implementation. The results of this work will have a significant impact on the design of integrated traffic management algorithms in both the Internet and ATM environments.