Dynamic ECN marking threshold algorithm for TCP congestion control in data center networks

Abstract

Recent years have witnessed the rapid development in data center, which hosts a wide variety of applications and services with diverse requirements for network performance. Data center networks (DCNs) have the characteristics of high bandwidth and low latency and TCP incast usually happens when multiple senders simultaneously communicate with a single receiver. In this paper, we first investigate the DCTCP, which is widely deployed in DCNs and uses Explicit Congestion Notification (ECN) as a congestion signal when queue length is larger than a fixed threshold. We demonstrate that the queuing delay may be high or the bottleneck link utilization can be insufficient due to inappropriate fixed threshold. Then we propose a dynamic ECN marking threshold algorithm based on the number of concurrent flows, referred to as DEMT, to improve the network performance. After that, an enhanced DEMT algorithm, referred to as EDEMT, is proposed by using the ratio of the queue length over the marking threshold to perceive the degree of network congestion. We also integrate DEMT with DCTCP to observe its behavior and theoretically analyze the throughput. Finally, simulation results demonstrate that the DEMT and EDEMT algorithms can effectively improve the network throughput while they can maintain a small queue length as well as the short flow completion time.