TCP BBR Performance Improvement on a Network with Increasing RTT
Kanon Sasaki, Kouto Miyazawa, Kohei Ogawa, Saneyasu Yamaguchi · 2020
TCP BBR, which was proposed in 2016, has become actually in use in some cases, so the performance fairness between the TCP BBR and other TCPs has become important. In this paper, we introduce an important issue of TCP BBR that its performance drops significantly after the start of a connection in a situation wherein TCP BBR connections communicate competitively with CUBIC TCP connections. For this issue, we reveal that this drop is caused by the increase in RTT by CUBIC TCP. We then propose a method for relieving this significant performance decline by updating its estimated RTT (Round-trip time) on a detection of a large difference between estimated and measured RTTs. We evaluate the proposed method and show that the proposed method substantially mitigates the significant performance drop.