Shaped Quota: More Efficient and More Versatile Congestion Control

Congestion control is one of the fundamental techniques for ensuring the stability and reliability of high-performance network applications. During the research on congestion control strategies for existing high-speed RDMA networks, it was observed that the current strategies are primarily applied in structured and stable data center networks, which are difficult to generalize to network environments with slightly poorer performance and packet loss. In this paper, we implement and analyze a receiver-driven end-to-end congestion control scheme called Shaped Quota for complex networks. Shaped Quota achieves rate control by actively evaluating the network congestion status of each flow at the receiver and providing feedback to the corresponding sender. Building upon this research, this paper further refines the design of the Shaped Quota and implements the algorithm for the first time in a simulated environment, followed by comprehensive testing. The experiments demonstrate that in lossless networks, Shaped Quota can provide superior transmission efficiency compared to existing congestion control schemes. Under lossy network conditions, Shaped Quota improves the reliability and stability of network transmission. Compared to DCQCN, Timely, and HPCC, Shaped Quota achieves an average reduction of 45.26% in Flow Completion Time (FCT) in lossless networks. In lossy networks, the flow completion rate of Shaped Quota is significantly higher, reaching 29.33 times and 29.24 times that of DCQCN and Timely, respectively. Compared to HPCC, which exhibits better queue length control, Shaped Quota reduces the queue length by more than 40%.