makidoll/google-tcp-brr.md

## google-tcp-brr.md

      
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              google-tcp-brr.md
            
          
    Increase server bandwidth using Google's TCP BRR

I'd recommend looking at my gist for Linux XanMod instead.
It includes BRR by default and more network optimizations.


Disclaimer: there's BRR2 or something but I haven't looked into it yet

TCP BRR (Bottleneck Bandwidth and RTT) is a congestion control algorithm.
Linux servers will use Reno and CUBIC algorithms by default which suck.
If you're running a homelab where ISP peering is garbage, BRR can really help.
Check what's enabled

# check available
sysctl net.ipv4.tcp_available_congestion_control
# check current
sysctl net.ipv4.tcp_congestion_control
If it prints cubic reno then you better go enable brr right now.
How to enable

Make sure you're using kernel 4.9 or higher. Check with uname -r
sudo nano /etc/sysctl.conf
And add to the very bottom:
net.core.default_qdisc=fq
net.ipv4.tcp_congestion_control=bbr
net.ipv4.tcp_window_scaling = 1
Apply using sudo sysctl -p
Check using the above commands if it's enabled.
Make sure to restart Docker too using sudo systemctl restart docker
Optionally docker exec into a container and run the same commands to check.
Original article

https://www.linuxbabe.com/ubuntu/enable-google-tcp-bbr-ubuntu
You can find lots of tests and data online if you look for it.