How to enable BBR on AlmaLinux 8

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 AlmaLinux 8 comes with the 4.18.0 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_available_congestion_control
net.ipv4.tcp_available_congestion_control = reno cubic

Enabling TCP BBR in AlmaLinux

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!