Abstract

To achieve high throughput and low latency for data center applications, there are two broad lines of work: end-to-end congestion control algorithms and flow pausing mechanisms. It is challenging for end-to-end congestion control algorithms without complex signals to achieve fast convergence to a stable equilibrium state while effectively handling the transient congestion. Additionally, flow pausing mechanisms are decoupled from congestion control, which leads to long convergence time after transient state and incomplete queue elimination in equilibrium state. We propose a transport protocol that combines the advantages of flow pausing and congestion control, called FAR. The key idea is coupling the bandwidth-estimation based congestion control and the end-to-end flow pausing mechanisms. FAR quickly explores the available bandwidth with binary-search based packet train probe to achieve high throughput and low latency. Extensive evaluation results demonstrate that our protocol achieves accurate bandwidth estimation and reduces the tail flow completion time (FCT) by up to 67Math 1 compared with the state-of-the-art designs.