Modern data-center applications generate a diverse mix of short and long flows with different performance requirements and weaknesses. The short flows are typically delay-sensitive but to suffer the head-of-line blocking and out-of-order problems. Recent solutions prioritize the short flows to meet their latency requirements, while damaging the throughput-sensitive long flows. To solve these problems, we design a Coding-based Adaptive Packet Spraying (CAPS) that effectively mitigates the negative impact of short and long flows on each other. To exploit the availability of multiple paths and avoid the head-of-line blocking, CAPS spreads the packets of short flows to all paths, while the long flows are limited to a few paths with Equal Cost Multi Path (ECMP). Meanwhile, to resolve the out-of-order problem with low overhead, CAPS encodes the short flows using forward error correction (FEC) technology and adjusts the coding redundancy according to the blocking probability. Moreover, since the coding efficiency decreases when the coding unit is too small or large, we demonstrate how to obtain the optimal size of coding unit. The coding layer is deployed between the TCP and IP layers, without any modifications on the existing TCP/IP protocols. The test results of NS2 simulation and small-scale testbed experiments show that CAPS significantly reduces the average flow completion time of short flows by ~30%–70% over the state-of-the-art multipath transmission schemes and achieves the high throughput for long flows with negligible traffic overhead.

中文翻译：

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CAPS：基于编码的自适应数据包喷涂，以减少数据中心中的流完成时间

现代数据中心应用程序会产生各种不同的短期和长期数据流，它们具有不同的性能要求和弱点。短流通常对延迟敏感，但是会遇到行头阻塞和乱序问题。最新的解决方案优先考虑短流量，以满足其延迟要求，同时破坏对吞吐量敏感的长流量。为了解决这些问题，我们设计了一种基于编码的自适应数据包喷雾（CAPS），可有效减轻短流和长流对彼此的负面影响。为了利用多路径的可用性并避免行首阻塞，CAPS将短流的数据包散布到所有路径，而长流则通过等价多路径（ECMP）限制为少数路径。同时，为了解决开销少的乱序问题，CAPS使用前向纠错（FEC）技术对短流进行编码，并根据阻塞概率调整编码冗余。此外，由于当编码单元太小或太大时编码效率都会降低，因此我们演示了如何获得最佳编码单元大小。编码层部署在TCP和IP层之间，而无需对现有TCP / IP协议进行任何修改。NS2仿真和小型试验台实验的测试结果表明，与最新的多径传输方案相比，CAPS可以将短流的平均流完成时间显着减少约30％–70％，并实现了高吞吐量。长流量，流量开销可忽略不计。此外，由于当编码单元太小或太大时，编码效率都会降低，因此我们演示了如何获得编码单元的最佳大小。编码层部署在TCP和IP层之间，而无需对现有TCP / IP协议进行任何修改。NS2仿真和小型试验台实验的测试结果表明，与最新的多径传输方案相比，CAPS可以将短流的平均流完成时间显着减少约30％–70％，并实现了高吞吐量。长流量，流量开销可忽略不计。此外，由于当编码单元太小或太大时，编码效率都会降低，因此我们演示了如何获得编码单元的最佳大小。编码层部署在TCP和IP层之间，而无需对现有TCP / IP协议进行任何修改。NS2仿真和小型试验台实验的测试结果表明，与最新的多径传输方案相比，CAPS可以将短流的平均流完成时间显着减少约30％–70％，并实现了高吞吐量。长流量，流量开销可忽略不计。