How to Enable BBR Congestion Control

Prerequisites

Before enabling BBR, make sure you have:

SSH access to your VPS
Root or sudo privileges
Kernel version 4.9 or higher

💡 BBR is a modern congestion control algorithm that can significantly improve TCP throughput and reduce latency, especially on long-distance connections.

Step 1: Check Current Kernel Version

Connect to your VPS:

ssh hxroot@YOUR_SERVER_IP -p 22

uname -r

Ensure version is 4.9 or higher (most modern VPS meet this).

Step 2: Check Available Congestion Control Algorithms

sysctl net.ipv4.tcp_available_congestion_control

If you see bbr in the list, it is available.

Step 3: Enable BBR

sudo modprobe tcp_bbr

echo "tcp_bbr" | sudo tee -a /etc/modules-load.d/modules.conf

Step 4: Set BBR as Default

sudo sysctl net.ipv4.tcp_congestion_control=bbr

Make permanent by adding to /etc/sysctl.conf:

echo "net.ipv4.tcp_congestion_control=bbr" | sudo tee -a /etc/sysctl.conf

Step 5: Verify BBR is Active

sysctl net.ipv4.tcp_congestion_control

Should output: net.ipv4.tcp_congestion_control = bbr

Check if module is loaded:

lsmod | grep bbr

Optional: Enable BBR with FQ (Fair Queueing) for Better Performance

sudo sysctl net.core.default_qdisc=fq

echo "net.core.default_qdisc=fq" | sudo tee -a /etc/sysctl.conf

Performance Comparison (BBR vs Cubic)

You can test using iperf3:

apt install iperf3 -y
# On server: iperf3 -s
# On client: iperf3 -c server_ip

✅ BBR congestion control has been enabled. Network performance should improve, especially for high-latency or lossy connections.