Unveiling TCP BBR Dominance in Starlink Internet: Experimental Insights and Analysis

Rakshitha De Silva, Shiva Raj Pokhrel, Jonathan Kua

This experimental study delivers a global assessment of Google's Bottleneck Bandwidth and Round-trip propagation time-version 3 (BBR-v3) Congestion Control Algorithm (CCA) over SpaceX's Starlink network. Leveraging a strategically deployed six-city testbed across five continents, we systematically benchmark BBR-v3 against eight CCAs: Cubic, Hybla, Vegas, LeoCC, Copa, PCC, BBR-v1, and BBR-v2 under both dedicated and concurrent conditions. Our results demonstrate that BBR-v3's advantage is not aggressive bandwidth capture, but a more balanced fairness, loss, and delay trade-off over the Starlink Internet. We develop pragmatic mathematical models that capture Starlink's complex network dynamics and characterize BBR-v3 behavior to better explain the experimental observations. Our extensive evaluation of queue buildup and fairness further demonstrates BBR-v3's capability to maximize throughput in high-latency, variable satellite environments, while maintaining a balance between aggressiveness and fairness. The findings establish BBR-v3 as a compelling CCA for Low Earth Orbit (LEO) satellite networks and provide a principled analytical foundation for next generation satellite Internet transport design.