A New Congestion-Based Congestion Control for Low Latency and Low Packet Drop Rate

In 2016, Google published BBR, a congestion-based congestion control algorithm that focuses on achieving the optimal operating point with the minimum delay and maximum throughput. When a single BBR flow occupies a bottleneck link, the packet sending rate and number of inflight packets of the flow achieve the optimal operating point. However, multiple BBR flows sharing a bottleneck link lead to a large latency and high packet drop rate. This is due to the maximum throughput being used for the packet sending rate, which makes the operating point far from optimal. In this paper, we propose a new congestion-based congestion control algorithm, called Low Latency and Low Drop Rate (L3DR), that keeps the operating point nearly optimal, even when multiple flows share a bottleneck link, by measuring the available bandwidth to be used for the packet sending rate. We conducted performance evaluation experiments in emulation network environments. The results indicate that L3DR can reduce the buffering delay to 38.5% and packet drop rate to 8.0% compared with BBR while achieving high throughput and high per-flow fairness.