How to Enable BBR on Debian 11

BBR stands for Bottleneck Bandwidth and RTT is a congestion control system. You can enable TCP BBR on your Linux desktop to improve overall web surfing experience. By default, Linux uses the Reno and CUBIC congestion control algorithm.

Requirements:

BBR requires Linux kernel version 4.9 or above. Since Debian 11 comes with the 4.19.0 kernel, we can enable BBR right away.

Run the following command to check available congestion control algorithms,

sysctl net.ipv4.tcp_available_congestion_control

Output:

[email protected]:~# sysctl net.ipv4.tcp_available_congestion_control
net.ipv4.tcp_available_congestion_control = reno cubic

Run the below command to check the current congestion control algorithm used in your system,

sysctl net.ipv4.tcp_congestion_control

Output:

[email protected]:~# sysctl net.ipv4.tcp_congestion_control
net.ipv4.tcp_congestion_control = cubic

Enabling TCP BBR in Debian

Open the following configuration file vi /etc/sysctl.conf to enable enable TCP BBR.

vi /etc/sysctl.conf

At the end of the config file, add the following lines.

net.core.default_qdisc=fq
net.ipv4.tcp_congestion_control=bbr

Save the file, and refresh your configuration by using this command,

sysctl -p

Output:

[email protected]:~# sysctl -p
net.core.default_qdisc = fq
net.ipv4.tcp_congestion_control = bbr

Now, Verify if BBR is enabled in your system,

sysctl net.ipv4.tcp_congestion_control

Output:

[email protected]:~# sysctl net.ipv4.tcp_congestion_control
net.ipv4.tcp_congestion_control = bbr

Done!