DC4: Reconstructing Data-Credit-Coupled Congestion Control for Data Centers

Congestion control is crucial for the overall performance of data center networks and still faces considerable challenges. Recently, credit-driven congestion control has been emerging to enable precise flow control for current high-speed and highly dynamic data centers. However, existing credit-driven methods essentially separate credit and data packets, i.e., credits can fully regulate data packets, but they receive little feedback from the data packets. Accordingly, these approaches inevitably struggle with lossy credits and impaired throughput. To address the issue, we present data-credit-coupling congestion control named DC4. For a better understanding of the relationship between data and credit, we revisit the principle of credit-based congestion control and make the first attempt to explore the art of presenting the data-credit plane architecture. Based on the proposed data-credit framework, DC4 transforms the interaction between credit and data packets from one-way control to two-way coordination to achieve mutual benefits and dynamic balances between the credit and data packets. We conduct extensive experiments to evaluate the performance of our design and compare it with state-of-the-art protocols, including HPCC, ExpressPass, and Aeolus. Experimental results show that DC4 outperforms data-credit-separated approaches in terms of the flow completion time, throughput, and credit waste.