Towards A Low-Latency Future Internet Transport

Abstract:

We have seen in recent times the emergence of a large number of low-latency TCP variants. Surprisingly, these modern low-latency TCP variants can match the performance of CUBIC and even outperform CUBIC for large RTT flows. We found that the likely reason is that the bottleneck buffers are relatively shallow and so these variants are likely throttling CUBIC by inflicting significant losses on the network. We present EvaRate, a new rate-based congestion control algorithm that incorporates a new buffer estimation technique which allows an EvaRate flow to infer its own buffer occupancy as well as that of the competing flows sharing the same bottleneck buffer. With this mechanism, an EvaRate flow is able to determine its operating environment and, when in a low-latency (or benevolent) environment, collaboratively regulates the bottleneck buffer occupancy with other EvaRate flows. By doing so, EvaRate avoids inflicting loss on the underlying network. We believe that our approach will allow the Internet to transition smoothly to a low-latency future without disrupting its current operation, as the proportion of low-latency TCP variant flows continues to increase.