An Efficient Scheduling Scheme for XMP and DCTCP Mixed Flows in Commodity Data Centers

Multi-path and single-path transport mechanisms with explicit congestion notification (ECN) have been proposed to share the commodity data center networks' (DCNs) fabric recently. The basic idea is that the throughput-sensitive long flows use explicit multipath (XMP) while the latency-sensitive short flows use data center TCP (DCTCP) to transfer data. However, the co-existence of DCTCP flows and XMP flows may cause an Incast collapse in a many to one transmission pattern, and DCTCP flows may have a higher chance to be marked and then slow down, which results in a longer flow completion time. In this letter, we propose an efficient scheduling scheme with ECN (ESE) for scheduling these two flows in commodity data centers. First, our scheme maintains dual service queues with ECN for DCTCP flows and XMP flows in commodity switches, respectively. In addition, we provide an extra queue with the highest priority to deliver urgent flows. Second, our scheme can dynamically adjust the number of subflows according to the extent of congestion, which effectively mitigates the Incast problem.