Studies on provision of Quality of Service for multi-class traffic on the Internet

(1)多类流量的流量控制和优先级控制研究在假设网络对多类流量具有优先级控制的情况下，我们首先提出了入口路由器的流量监控、标记和调度机制，并通过解析方法和计算机模拟对这些机制的性能进行了评估。通过一些数值结果，我们研究了网络中每种业务类型可达到的服务质量(Qos)。多类流量的路由机制研究我们首先研究了一种能够有效地为每个实时流量分配带宽、提高尽力而为流量(如TCP)吞吐量的路由机制。在该机制中，我们引入了两类业务的“虚拟剩余带宽”的概念。以“虚拟剩余带宽”作为路由度量，通过计算机仿真评估了路由性能，并在试验台网络上进行了验证。我们进一步研究了重新路由机制的性能，该机制重新分配已建立的流量以接受新到达的和高优先级的流量。

(1) Study on traffic policing and priority control for multi-class trafficSupposing the network with priority control for multi-class traffic, we first propose mechanisms for policing, marking and scheduling at ingress routers and evaluate these performance by both analytical approach and computer simulation. Through some numerical results, we investigated achievable Quality of Service(QoS) of each traffic type in the network. We then propose mechanisms for inferring QoS in some network and explained its effectiveness.(2) Study on the routing mechanism for multi-class trafficWe first investigate the routing mechanism which effectively allocates bandwidth to each real-time traffic and improves throughput of best-effort traffic such as TCP. In the mechanism, we introduced the concept of "virtual residual bandwidth" for both classes of traffic. By using "virtual residual bandwidth" as routing metric, we evaluated routing performance by computer simulation and made clear it on the test-bed network. We further investigate performance of re-routing mechanism which re-allocates established traffic for accepting newly arrival and high-priority traffic.