How to install BBR on CentOS
Since CentOS 7 ships with the 3.10.x kernel, which does not include BBR by default, we need to upgrade to a newer kernel version on your machine to use BBR.
For this, we install the ELRepo repo,
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
Output:
[root@vps ~]# rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
[root@vps ~]# rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
Retrieving http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
Retrieving http://elrepo.org/elrepo-release-7.0-4.el7.elrepo.noarch.rpm
Preparing... ################################# [100%]
Updating / installing...
1:elrepo-release-7.0-4.el7.elrepo ################################# [100%]
[root@vps ~]#
To install kernel using the ELRepo repo,
yum --enablerepo=elrepo-kernel install kernel-ml -y
Output:
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
kernel-ml x86_64 5.12.9-1.el7.elrepo elrepo-kernel 53 M
Transaction Summary
================================================================================
Install 1 Package
.
.
.
Installed:
kernel-ml.x86_64 0:5.12.9-1.el7.elrepo
Complete!
Now check the stable kernel installation by using the following command,
rpm -qa | grep kernel
Note: If the installation is successful, you should see kernel-ml-5.xx.xx.elrepo.x86_64 among the output list:
Output:
[root@vps ~]# rpm -qa | grep kernel
kernel-3.10.0-1160.el7.x86_64
kernel-tools-3.10.0-1160.el7.x86_64
kernel-ml-5.12.9-1.el7.elrepo.x86_64
kernel-tools-libs-3.10.0-1160.el7.x86_64
[root@vps ~]#
Boot into the newer Kernel
Next, you need to boot into the latest kernel by setting it as the default grub2 boot entry.
Command to show all entries in the grub2 menu,
egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \'
Output:
[root@vps ~]# egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \'
CentOS Linux 7 Rescue 13f95ded0c4147935ac6afed832cfb0a (5.12.9-1.el7.elrepo.x86_64)
CentOS Linux (5.12.9-1.el7.elrepo.x86_64) 7 (Core)
CentOS Linux (3.10.0-1160.el7.x86_64) 7 (Core)
CentOS Linux (0-rescue-dd1973a114f84ea8bbf37b494513d3f7) 7 (Core)
Use the following command to set the default boot entry,
Note: The count starts from 0 and the latest stable kernel is on the second line thus we set it to 1
For example,
[root@vps ~]# egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \'
CentOS Linux 7 Rescue 13f95ded0c4147935ac6afed832cfb0a (5.12.9-1.el7.elrepo.x86_64) <-- 0
CentOS Linux (5.12.9-1.el7.elrepo.x86_64) 7 (Core) <-- 1
CentOS Linux (3.10.0-1160.el7.x86_64) 7 (Core) <-- 2
CentOS Linux (0-rescue-dd1973a114f84ea8bbf37b494513d3f7) 7 (Core) <-- 3
grub2-set-default 1
Reboot the server
shutdown -r now
Once the server is back online, confirm that you are using the correct kerne.
uname -r
Output:
[root@vps ~]# uname -r
5.12.9-1.el7.elrepo.x86_64
Enable Google BBR.
You need to modify systctl as follows to enable the Google BBR algorithm.
echo 'net.core.default_qdisc=fq' | tee -a /etc/sysctl.conf
echo 'net.ipv4.tcp_congestion_control=bbr' | tee -a /etc/sysctl.conf
sysctl -p
Output:
[root@vps ~]# echo 'net.core.default_qdisc=fq' | tee -a /etc/sysctl.conf
net.core.default_qdisc=fq
[root@vps ~]# echo 'net.ipv4.tcp_congestion_control=bbr' | tee -a /etc/sysctl.conf
net.ipv4.tcp_congestion_control=bbr
[root@vps ~]# sysctl -p
net.core.default_qdisc = fq
net.ipv4.tcp_congestion_control = bbr
Run the following command to verify if BBR is enabled,
sysctl net.ipv4.tcp_available_congestion_control
Output:
[root@vps ~]# sysctl net.ipv4.tcp_available_congestion_control
net.ipv4.tcp_available_congestion_control = reno cubic bbr
Finally, execute the following command to verify the Google BBR,
lsmod | grep bbr
Output:
[root@vps ~]# lsmod | grep bbr
tcp_bbr 20480 1
How to Enable BBR on Ubuntu 22.04
BBR stands for Bottleneck Bandwidth and RTT is a congestion control system. You can enable TCP BBR on your Linux desktop to improve the overall web surfing experience. By default, Linux uses the Reno and CUBIC congestion control algorithm.
Run the following command to check available congestion control algorithms,
sysctl net.ipv4.tcp_available_congestion_control
Output:
root@crown:~# sysctl net.ipv4.tcp_available_congestion_control
net.ipv4.tcp_available_congestion_control = reno cubic bbr
Run the below command to check the current congestion control algorithm used in your system,
sysctl net.ipv4.tcp_congestion_control
Output:
root@crown:~# sysctl net.ipv4.tcp_congestion_control
net.ipv4.tcp_congestion_control = bbr
Enabling TCP BBR in Ubuntu
Open the following configuration file /etc/sysctl.conf to enable enable TCP BBR.
nano /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:
root@crown:~# 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:
root@crown:~# sysctl net.ipv4.tcp_congestion_control
net.ipv4.tcp_congestion_control = bbr