Tiny Buffer TCP for Data Center Networks

TL;DR

Tiny Buffer TCP (TBTCP) introduces novel congestion control schemes that drastically reduce buffer size requirements while maintaining high throughput and fairness in data center networks.

Contribution

TBTCP employs innovative congestion window adjustment schemes with ECN to significantly lower buffer needs and improve network performance over existing protocols.

Findings

Reduces switch buffer requirement by over 80%.

Increases bandwidth utilization by up to 15%.

Improves RTT fairness index by 71%.

Abstract

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.