Incast-Aware Switch-Assisted TCP Congestion Control for Data Centers

Due to the partition/aggregate nature of many cloud applications, incast traffic is preponderant in data center networks (DCNs). Because TCP is agnostic to this composite nature of the applications traffic and their quality of service requirements, a few congestion events often degrade significantly the user perceived quality of service. This is exacerbated by the co-existence of such incast traffic with other elastic traffic flows in the network. In this paper we address the congestion problems of incast traffic and its interaction with other elastic traffic in DCNs. We propose a switch- assisted TCP congestion control via some small modifications to the switch software that do not require any modification to the TCP protocol nor to the TCP sender or receiver logic. We assess the performance of the proposed scheme via ns2 simulation as well as a real deployment in a small-scale testbed¹.