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BBR TCP

BBR is a new TCP congestion control algorithm that uses estimated congestion rather than loss to determine when to back off. More information on BBR is available in in these papers/talks:

Note that BBR v1 is known to compete unfairly with CUBIC, HTCP, etc, so we do not recommend it on networks that use other types of congestion control. BBR v2 reportedly solves this, but is not yet available in a supported kernel release. 

BBR is included starting with version 4.9 of the Linux kernel, and therefore is in RHEL/CentOS 8.0, Debian 9, and Ubuntu 17. The latest kernel can and easily installed on RHEL/CentOS 6/7-based hosts via ELRepo.

BBR v2 preview release is available here

Our initial testing shows that BBR can help a lot on certain links. 50% performance improvements are common on some paths. But more testing is needed. Those interested in BBR should do extensive testing in their environment, and follow the discussion on the BBR discussion group list before deploying it on production systems. Please give it a try and let us know your results.

More test results and discussion on BBR TCP are available on the BBR discussion group list.

Also note that TCP improvements such as BBR are not a substitute for good network design (e.g.: a ScienceDMZ) or the need to reduce packet loss to a minimum. BBR may reduce the impact of packet loss, but does not eliminate it.