Congestion Window Scaling Method for Inter-protocol Fairness of BBR

Abstract

Unlike the existing loss-based and delay-based congestion control algorithms, the Bottleneck Bandwidth Round-trip propagation time (BBR) congestion control algorithm determines the amount of sending data to be transferred at a specific time by calculting BDP (Bandwidth Delay Product). However, when BBR competes with loss-based congestion control algorithms, such as Reno and CUBIC, most of the bottleneck bandwidth is occupied by specific flows or excessive packet loss occurs. In previous work, we proposed an improved loss recovery mechanism in order to address above problems. Through the previous proposal, the fairness between BBR and loss-based algorithms was improved if the buffer size was larger than 2 BDP. However, if the buffer size was smaller than 2 BDP, the performance imbalance and continuous packet retransmission still occurred. In this paper, we propose a congestion window upper scaling method that complements the previously proposed loss recovery mechanism. In addition, we conduct an experiment and evalute its enhanced performance in a Mininet emulator.