PABO: Congestion Mitigation via Packet Bouncing

Zhiyong Liu
Chair Professor
The Institute of Computing Technology Chinese Academy of Sciences, China
SERC 306
Wednesday, February 22, 2017 - 11:00
Data center applications can generate a diverse mix of short and long flows. However, switches used in a typical data center network are usually shallow buffered. As a result, the buildup of the queues by long flows can block short flows, leading to frequent packet losses and retransmissions, which translates to crucial performance degradation. In this talk, I will introduce a novel link-layer protocol, PABO, that can mitigate congestions by bouncing packets back to the upstream switches. The design of PABO meets the following demands: i) providing per-flow based flow control on the link layer, ii) handling transient congestion without the intervention of end devices, and iii) gradually back propagating the congestion signal to the source when the network is not capable to handle the congestion. Experiments for a preliminary implementation of PABO show that PABO outperforms the standard unreliable link-layer protocol by guaranteeing zero packet loss while introducing only a reasonable stretch on packet delay.