Receiver-driven fair congestion control for TCP outcast in data center networks

摘要

In the commodity data center networks with multi-rooted tree topologies, the close TCP flows are easily suppressed by the far ones, resulting in large tail flow completion time. The existing solutions, however, are mainly window-based and unable to control the micro-burst congestion, leading to performance degradation. In this paper, we reveal empirically that controlling the micro-burst of highly concurrent flows effectively alleviates this TCP outcast problem under severe congestion. We propose the receiver-driven congestion control OFTCP by coordinating the many-to-one flow transmission. Specifically, OFTCP randomly defers ACK transmissions in a small time granularity to mitigate the aggregate micro-burst and cooperatively adjusts the advertisement windows of each flow based on round trip time to provide fair transmission. We evaluate the performance of OFTCP with Mininet testbed and NS2 simulation under realistic datacenter workloads. Experiment results show that OFTCP achieves throughput fairness and reduces the tail flow completion time by up to 53% compared with state-of-the-art datacenter outcast solutions.