支持链路共享的流量整形器

针对英特网的一些接入场合，特别是有服务质量（QoS）要求的场合，对共享一条物理链路
的多个逻辑链路的分组流量进行整形。引用分级链路共享树概念，对应每个类设置一个令牌桶，使得在实
现分级链路共享的同时可以对任意一个类的业务流进行整形，限制其速率和突发。对于带宽不需要限制的
类，改进基于令牌桶的调度算法，使这些类具有借用空余带宽的能力，以便提高带宽利用率。理论分析和
仿真结果表明，该流量整形器通过依权重公平分享令牌途径，保证每个类的基本带宽服务并可以依权重公
平分享空余带宽，从而实现高效的分级链路共享功能。

Traffic shaper supporting link-sharing

In some Internet connections, especially with the requirement of quality of service (QoS), traffic shaping is needed for the logical links sharing a single physical link. This work introduced the concept of hierarchical link-sharing tree, and bounded a token bucket with each class in the hierarchy, thus made it possible to shape the traffic of any class and limit the rate and burst while performing link sharing. For some classes that do not need bandwidth restriction, the token bucket based scheduling algorithm was improved to bestow these classes the ability to borrow excess bandwidth, so as to make better use of the bandwidth. Analysis and simulation results show that through the method of weighted fair token sharing, the traffic shaper can guarantee the basic bandwidth service for each class and enable weighted fair sharing of excess bandwidth, therefore perform efficient hierarchical link-sharing.