End-to-end Credit-based Congestion Control For Data Center Networks

For data center networks(DCNs),the network fabric evolves a lot to serve global users,but network congestion inevitability occurs when traffic bursts as well.To efficient manage congestion in current high-speed DCNs,researchers devote much attention to the proactive congestion control which has the merits of fast convergence,low latency,and low buffer occupancy.ExpressPass,as a state-of-the-art proactive scheme,leverages credit reservation mechanism to achieve fast transmission,where each credit schedules one maximum transmission unit(MTU)data packet.However,for workloads with a high volume of very short flows that shorter than an MTU,the credit efficiency is degraded and the link bandwidth is wasted.This paper proposes ExpressPass++ to improve the credit scheduling mechanism of ExpressPass.ExpressPass++ develops a token-scheduled protocol,each credit corresponds to an MTU size tokens which can schedule an MTU amount of data.Since a credit may schedule multiple small packets,data packets will carry reduplicative credit sequence number that used for feedback control and the credit rate will be inaccurately regulated.To address this problem,ExpressPass++ improves the sequence-based feedback control of ExpressPass.Compared to ExpressPass,the results show that ExpressPass++ greatly improves in terms of average FCT and network utilization,and ExpressPass++ maintains the ExpressPass' s advantages of the bounded queue and fast convergence.