How to enable tcp bbr in FreeBSD???

Michael Tuexen tuexen at
Fri Apr 24 19:25:23 UTC 2020

> On 24. Apr 2020, at 21:06, Rodney W. Grimes <freebsd-rwg at> wrote:
>> On Fri, Apr 24, 2020 at 01:31:35PM +0200, Kurt Jaeger wrote:
>>> Thanks. Is BBR active automatically or is there a sysctl or
>>> socket option to activate it ?
>> List available congestion control algorithms
>> Default congestion control algorithm
> Start at:
> man mod_cc
BBR is conceptually a CC, but in FreeBSD it is NOT implemented as a CC module.
It is a TCP stack. You need to load it using
kldload tcp_bbr
and then either make it the default by
sudo sysctl net.inet.tcp.functions_default=bbr
or use the IPPROTO_TCP level socket option TCP_FUNCTION_BLK to set the stack
to BBR. The uperf test tool allows to set the TCP stack for measurements.
Please note that you need to compile the kernel with
options		TCPHPTS

Best regards
> -- 
> Rod Grimes                                                 rgrimes at
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