Buffer sizes for large multiplexers: TCP queueing theory and instability analysis
Buffer sizes for large multiplexers: TCP queueing theory and instability analysis
复制标题
大型多路复用器的缓冲区大小：TCP 排队理论和不稳定性分析
DOI：
10.1109/ngi.2005.1431663
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Damon Wischik
中科院分区：
文献类型：
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作者：
Gaurav Raina;Damon Wischik
在具有许多TCP流的大型复用器中，总的业务流表现为可预测的；这是Misra、Gong和Towsley V.Misra等人(2000)的流体模型以及关于拥塞控制的流体模型的不断增长的文献的基础。在这篇文章中，我们认为不同的流体模型产生于不同的缓冲大小调整制度。我们考虑大缓冲区(缓冲区大小是带宽延迟乘积)、中间缓冲区(用大缓冲区大小除以流量的平方根)和小缓冲区(缓冲区大小与流量无关)。我们的论证使用了排队论中的各种技巧。我们研究了这些流体模型的行为(在单个瓶颈Kink上，对于一组相同的长寿命流)。对于什么参数区域，流体模型是稳定的，当它不稳定时，振荡的大小和对产出的影响是什么？我们的分析使用了Poincare-Linstedt方法的扩展来求解时滞微分方程。我们发现，具有Drop-Tail的大缓冲区与具有Drop-Tail或AQM的中间缓冲区具有大致相同的性能；具有红色的大缓冲区至少对于小于20个分组的窗口大小更好；并且具有Drop-Tail或AQM的小缓冲区在广泛的窗口大小范围内最好，尽管缓冲区大小必须谨慎选择。这表明缓冲区大小应该比当前推荐的小得多。
In large multiplexers with many TCP flows, the aggregate traffic flow behaves predictably; this is a basis for the fluid model of Misra, Gong and Towsley V. Misra et al., (2000) and for a growing literature on fluid models of congestion control. In this paper we argue that different fluid models arise from different buffer-sizing regimes. We consider the large buffer regime (buffer size is bandwidth-delay product), an intermediate regime (divide the large buffer size by the square root of the number of flows), and the small buffer regime (buffer size does not depend on number of flows). Our arguments use various techniques from queueing theory. We study the behaviour of these fluid models (on a single bottleneck Kink, for a collection of identical long-lived flows). For what parameter regimes is the fluid model stable, and when it is unstable what is the size of oscillations and the impact on goodput? Our analysis uses an extension of the Poincare-Linstedt method to delay-differential equations. We find that large buffers with drop-tail have much the same performance as intermediate buffers with either drop-tail or AQM; that large buffers with RED are better at least for window sizes less than 20 packets; and that small buffers with either drop-tail or AQM are best over a wide range of window sizes, though the buffer size must be chosen carefully. This suggests that buffer sizes should be much much smaller than is currently recommended.