Abstract: To address issues such as insufficient bandwidth utilization, slow convergence speed, and inadequate fairness in multi-flow shared link scenarios with existing RoCE (RDMA over converged Ethernet) network protocols, a dynamic rate adaptive increment algorithm based on sending rate gradient (DRAI) is proposed and improved upon the foundation of the HPCC (high precision congestion control) protocol. First, the switch adds in-band network telemetry (INT) information containing fields such as link capacity and the maximum number of concurrent flows to data packets. Then, the receiver returns ACK packets carrying the same INT information. Finally, the sender calculates the rate gradient at the congestion points using the INT information and employs this as a signal to implement a dynamic additive-increase factor, adopting a multiplicative-increase multiplicative-decrease (MIMD) rate adjustment strategy to control the sending rate. Experimental results show that, compared to the HPCC protocol, the proposed congestion control algorithm achieves faster convergence and better fairness in multi-flow shared link scenarios. While maintaining comparable short-flow flow completion times (FCTs) to the HPCC protocol, it also reduces the 99th-percentile FCT for long flows in high-load scenarios.

Key words: data center network, remote direct memory access, congestion control, in-band network telemetry, RDMA over converged ethernet network protocol