SDN-based TCP Congestion Control in Data Center Networks

TCP incast usually happens when a receiver requests the data from multiple senders simultaneously. This many-to-one communication pattern constantly appears in the data center networks due to the data are stored at multiple servers. With Software Defined Networks (SDN), the centralized control methods and the global view of the network can be an effective way to handle this problem. In this paper, we propose a SDN-based TCP (SDTCP) congestion control mechanism at network side. Our approach enables controller to select a long-lived flow to reduce sending rate by adjusting the TCP receive window of ACK packet after OpenFlow-switch triggered a congestion message to controller. The key benefit of SDTCP is that, with global perspective, we can accurately decelerate the rate of long-lived flow to ensure the performance other flows. The experiments indicate that we can achieve almost zero packet loss for TCP incast and guarantee goodput for the high propriety flows.