BBR (Bottleneck Bandwidth and Round-trip) Optimization Guide

A high-performance TCP congestion control algorithm for Linux

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📌 What is BBR?

BBR (Bottleneck Bandwidth and Round-trip propagation time) is a TCP congestion control algorithm developed by Google. Unlike traditional loss-based algorithms (e.g., CUBIC), BBR:
✅ Dynamically adjusts sending rates based on real-time bandwidth and latency.
✅ Reduces bufferbloat (excessive queuing delays).
✅ Improves throughput on high-latency or lossy networks (e.g., international connections).

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🚀 How to Enable BBR on Linux

1. Check Current Congestion Control

sysctl net.ipv4.tcp_congestion_control

(Default: usually cubic or reno)

2. Enable BBR (One-Time)

sudo bash -c 'echo "net.core.default_qdisc=fq" >> /etc/sysctl.conf'
sudo bash -c 'echo "net.ipv4.tcp_congestion_control=bbr" >> /etc/sysctl.conf'
sudo sysctl -p  # Apply changes

3. Verify BBR is Active

sysctl net.ipv4.tcp_congestion_control  # Should output "bbr"
lsmod | grep bbr  # Check if BBR module is loaded

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⚙️ Advanced Tuning (Optional)

BBR v2/v3 (Kernel ≥5.10+)

# For BBRv2 (if compiled in kernel):
sudo bash -c 'echo "net.ipv4.tcp_congestion_control=bbr2" >> /etc/sysctl.conf'

# For BBRv3 (latest Linux kernels):
sudo bash -c 'echo "net.ipv4.tcp_congestion_control=bbr" >> /etc/sysctl.conf'

Custom Parameters

# Increase TCP buffer sizes (adjust based on your bandwidth):
echo "net.core.rmem_max=4194304" | sudo tee -a /etc/sysctl.conf
echo "net.core.wmem_max=4194304" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

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📊 Performance Comparison

Metric	CUBIC (Default)	BBR	BBRv2/v3
Throughput	Moderate	High	Very High
Latency	Variable	Low	Very Low
Fairness	Good	Better	Best

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⚠️ Notes & Caveats

1. Kernel Requirement: BBR requires Linux 4.9+. For BBRv2/v3, use 5.10+.
   • Check kernel: uname -r
2. Not All Networks Benefit: BBR excels in high-latency/lossy networks but may underperform in local LANs.
3. Compatibility Issues: Some outdated middleboxes (e.g., firewalls) may interfere.

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📚 Further Reading

• Google BBR Paper
• Kernel Documentation

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🎯 Why Use This Script?

This project (Ya-MIC BBR Manager) automates the above steps and adds:
🔹 One-click installation for BBRv1/v2/v3.
🔹 Dynamic tuning based on network conditions.
🔹 Support for multiple Linux distros (Debian/Ubuntu/CentOS).

👉 Get Started:

wget https://github.com/Ya-MIC/bbr-manager/install.sh && sudo bash install.sh

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License

MIT © Ya-MIC

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