Don't Drop, Detour!

摘要

Modern data center networks (DCNs) are built with shallow-buffered switches. These switches are cheaper than their deep-buffered counterparts, and they also reduce the maximum queuing delays packets may suffer. However, shallow buffers can lead to high packet loss under bursty traffic conditions (often caused by the "incast" traffic pattern [7]). DCTCP [3] attempts to solve this problem by using ECN markings to throttle the flows early, to avoid buffer overflow. However, DCTCP cannot prevent packet loss if the traffic bursts are severe, and short-lived. One extreme example is a large number of senders each sending one or two packets to a single receiver. No feedback-based congestion control protocol can prevent buffer overflow and packet losses under such extreme conditions. One reason for this is an assumption ingrained in today's DCN design.