BBR is a congestion control algorithm for TCP and QUIC that optimizes network throughput and latency by measuring bottleneck bandwidth and round-trip time rather than relying solely on packet loss as a congestion signal.
The algorithm addresses the problem that traditional loss-based congestion control algorithms can underutilize available bandwidth and introduce unnecessary queuing delays. BBR works by continuously measuring the maximum bandwidth and minimum round-trip time on a connection, then adjusting the sending rate to match the bottleneck bandwidth while maintaining a small queue. This approach reduces latency spikes and improves throughput, particularly on high-bandwidth, high-latency networks and in the presence of packet loss.
The project provides implementations for both Linux TCP and QUIC protocols. Developers should adopt BBR if they operate networks where reducing latency and improving throughput matter, or if they want to experiment with modern congestion control approaches. The repository serves primarily as a reference implementation and documentation hub rather than a standalone deployment package; the latest Linux TCP BBR code is integrated into the kernel, while QUIC implementations are maintained in Google's QUICHE repository. The project includes quick-start guides for building and running BBR on Google Compute Engine, an FAQ addressing common questions, and an Internet Draft specification being developed through the IETF Congestion Control Working Group.
Development activity centers on maintaining multiple versions and implementations. The project tracks both BBRv3 and earlier v1 releases for Linux TCP, with corresponding QUIC implementations in the QUICHE repository. An active public mailing list welcomes test results, performance evaluations, and feedback from the community. The team collaborates with IETF working group members on standardizing the algorithm through an Internet Draft, accepting both GitHub issues for suggestions and pull requests for editorial improvements to the specification.
