A fuzzy threshold controller for priority traffic in ATM networksis presented The controller is based on fuzzy theory and PED control principle. The new approach can perform much better than the fixed threshold mechanism through adjusting the threshold periodically and adaptivelly and adaptively according to the arriving traffic load and charac teristics.

This paper fist revistits the previously proposed NSAD (New Self-Adapt DCF) mechanism. Some modifications are presented to further enhance the performance of NSAD in the error-prone environment. Then a new NAC mechanism is proposed that can realize bandwidth guarantee by assigning different. self-adapt parameters to users at different priority levels. the bandwidth guarantee property of this new mechanism is analyzed and the highpriority users are found to have bandwidth guaranteed even in heavy contention condition, which is proved true not only by theoretical analysis but also by simulatin results. At the same time the new scheme keeps the self-adapt character of NSAD, so the overall system utilization is kept very high in heavy contention condition compared with the previously studied DCF-based QoS mechanisms.

This paper presents a more complete analytical model of multiple TCP connections established between a busy server and multiple receivers. In such case, the server may become the bottleneck of the whole system, and TCP behaviors are different from the model presented before. Based on the analysis of working flows in the system and a M/G/1 queueing model, the RTT and long-term TCP throughput formulae are derived in terms of number of TCP connections, packet loss rate, and end-to-end delay. And the effect of maximum window size is also investigated. Finally, the simulation results confirm the effectiveness of analytical model.

本文介绍了Internet端到端测量技术的最新进展，包括性能拓扑推测、时延测量、丢包率测量。最后讨论了未来Internet端到端测量的研究趋势和应用前景。