Resolving Congestion Packet Losses for Small Flows in Datacenter Networks with Link-local Retransmission

With the increasing demand for high-performance computing (HPC) and artificial intelligence (AI), the transmission rates of data center networks have rapidly increased. However, this rise in link rate has not been accompanied by a proportional increase in switch buffer sizes, leading to an increase in the number of small flows and exacerbating buffer overflow problems. Traditional TCP and PFC mechanisms are ineffective in alleviating the flow completion time (FCT) issues of small flows. To address this, this paper proposes an improved solution based on the Link Local Retransmission (LLR) technique, called LLR-CoLoR. The approach works by backing up packets during congestion and precisely retransmitting lost packets, thereby avoiding the negative impacts of the PFC mechanism. This significantly reduces the FCT of small flows and improves the overall performance of data center networks. Large-scale topology experiments conducted on NS3 show that LLR-CoLoR reduces the FCT slowdown of small flows by more than 4X compared to other algorithms.