Binary increase congestion control (BIC) for fast long-distance networks
Binary increase congestion control (BIC) for fast long-distance networks
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DOI：
10.1109/infcom.2004.1354672
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
Lisong Xu;Khaled Harfoush;I. Rhee
中科院分区：
文献类型：
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作者：
Lisong Xu;Khaled Harfoush;I. Rhee
具有大延迟的高速网络提供了一种独特的环境，其中TCP可能在利用全部带宽方面存在问题。已经提出了几种拥塞控制建议来解决这个问题。现有的协议主要考虑两个属性：TCP友好性和带宽可扩展性。也就是说，协议在利用高速网络的全部带宽的同时，不应该从标准TCP流中占用太多带宽。这项工作提出了另一个重要的约束，即RTT（往返时间）的不公平性，竞争流与不同的RTT可能会消耗非常不公平的带宽份额。现有的方案有一个严重的RTT不公平的问题，因为拥塞窗口的增长率越来越大，窗口的增长具有讽刺意味的是，正是因为这样，使他们更具有可扩展性。对于具有大拥塞窗口的流，其中分组丢失可以高度同步，对于高速网络的RTT不公平性明显地发生在丢弃尾路由器。针对现有协议存在的RTT不公平问题，提出了一种新的拥塞控制方案，在支持TCP友好性和带宽可扩展性的同时，解决了RTT不公平问题。提出的拥塞控制算法使用两种窗口大小控制策略，称为加法增加和二进制搜索增加。当拥塞窗口较大时，以较大增量的加性增加确保了平方RTT不公平性以及良好的可扩展性。在小拥塞窗口下，二分查找增加支持TCP友好性。仿真结果证实了这些属性的协议。
High-speed networks with large delays present a unique environment where TCP may have a problem utilizing the full bandwidth. Several congestion control proposals have been suggested to remedy this problem. The existing protocols consider mainly two properties: TCP friendliness and bandwidth scalability. That is, a protocol should not take away too much bandwidth from standard TCP flows while utilizing the full bandwidth of high-speed networks. This work presents another important constraint, namely, RTT (round trip time) unfairness where competing flows with different RTTs may consume vastly unfair bandwidth shares. Existing schemes have a severe RTT unfairness problem because the congestion window increase rate gets larger as the window grows ironically the very reason that makes them more scalable. RTT unfairness for high-speed networks occurs distinctly with drop tail routers for flows with large congestion windows where packet loss can be highly synchronized. After identifying the RTT unfairness problem of existing protocols, This work presents a new congestion control scheme that alleviates RTT unfairness while supporting TCP friendliness and bandwidth scalability. The proposed congestion control algorithm uses two window size control policies called additive increase and binary search increase. When the congestion window is large, additive increase with a large increment ensures square RTT unfairness as well as good scalability. Under small congestion windows, binary search increase supports TCP friendliness. The simulation results confirm these properties of the protocol.