Tiny Buffer TCP for Data Center Networks
A low and stable buffer occupancy is critical to achieve high throughput, low packet drop rate, low latency, and low jitter for data center networks. It also allows switch chips to support higher port density, larger lookup tables, or richer functions. Tiny Buffer TCP creatively uses the common RED-based ECN with two novel congestion-window adjustment schemes to significantly reduce the required buffer size. Aiming to eliminate the residual packets in the bottleneck queue, Queue Canceling Decrease amortizes the ideal window reduction to the same number of flows so as to minimize the impact to active flows. In order to keep the buffer occupancy low and stable, Reduced Additive Increase recovers the flow window at a slower pace than normal. We implemented TBTCP in Linux kernel and conducted ns2-based simulations and real network-based tests. Our results show that compared to DCTCP, TBTCP reduces the switch buffer requirement by more than 80%, increases the bandwidth utilization by up to 15%, improves the FCT performance by up to 39%, and achieve a 71% better RTT fairness index.