Code Archaeology

Mar 5, 2026 · Backend Development

Why BBR Couldn't Dethrone CUBIC as Linux's Default TCP Congestion Control

This article analyzes Google's BBR congestion control algorithm, comparing its model-driven approach with CUBIC's loss-based design, explains why BBR hasn't become Linux's default despite advantages in high-BDP and wireless scenarios, details BBRv2/v3 improvements addressing fairness and robustness, and examines the Linux kernel's congestion control framework implementation.