A Delay-Based TCP for Solving Incast Problem in Data Centers

TCP incast problem has become a severe problem in datacenters due to the catastrophic collapse of goodput at the receiver side. Many solutions have been proposed, however, none of them solved it fundamentally. In this paper, we take a deep dive into the causes of incast problem, and find out that the root cause of TCP incast is the droptails induced by TCP congestion control algorithm based on packet losses. According to the root cause, we design a new TCP based on FAST TCP, a delay based congestion control algorithm, to radically solve TCP incast problem. The new TCP aims at maintaining a small and relatively constant queue length that does not exceed the switch buffer and meanwhile fully occupy the bottleneck link. The evaluation results in both simulation and real system demonstrate that our method cuts off most of the timeouts and attains high goodput under various conditions.