Update kernel

Install ELRepo Repository
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh https://www.elrepo.org/elrepo-release-7.0-3.el7.elrepo.noarch.rpm
Install the new kernel and enable it
yum -y --enablerepo=elrepo-kernel install kernel-ml
grub2-set-default 0
reboot

Open BBR and reboot

echo "net.core.default_qdisc=fq" >> /etc/sysctl.conf
echo "net.ipv4.tcp_congestion_control=bbr" >> /etc/sysctl.conf
sysctl –p

Check for success

sysctl net.ipv4.tcp_available_congestion_control
sysctl net.ipv4.tcp_congestion_control
sysctl net.core.default_qdisc
lsmod | grep bbr

Delete the old kernel

yum -y remove kernel kernel-tools