A cross-layer flow schedule with dynamical grouping for mitigating larger-scale TCP incast

Abstract

Data center network (DCN), a type of network featuring low delays and high bandwidths, exchanges information rapidly through high-performance network switches. Currently, DCN provides various distributed services to satisfy user requirements. However, the size of buffers in the switches of DCNs is limited, thus causing throughput collapse when transmission control protocol (TCP) is used for multiple-to-one transmissions. Dropped packets result in additional retransmission costs and cause a substantial decrease in the efficient use of network bandwidths. Such a decrease in network performance is called a TCP incast problem. Previous studies have typically focused on modifying the original TCP or increasing additional switch hardware costs; rarely have studies focused on the existing DCN environments. Therefore, this study proposes using a cross-layer flow schedule with dynamical grouping (CLFS-DG) scheme to reduce the effect of TCP incast in DCNs. In CLSF-DG, data transmission schedules are organized by a receiver using application-level information. Multiple data flows are then grouped for simultaneously transmission to improve TCP throughput and satisfy deadline requirements. CLFS-DG can be applied to inexpensive switches without extra hardware support, substantially reducing hardware costs. The simulation result indicated that CLFS-DG can effectively prevent TCP incast occurrence and ensure the quality of service in both local networks and fat-tree topologies typically applied in the DCN. A realistic multiple-to-one transmission in the one-hop local network scenario had been set up and tested. The average error rate of the simulation results and actual experimental results is small and about 4.6%. The results show that CLFS-DG can actually be applied to real large networks.