Preamble

Enabling BBR and configuring TCP parameters on Debian 13 requires modifying system kernel parameters. The following provides detailed operational procedures[1][9].

Prerequisites Verification

First, verify that the kernel version meets the requirements. BBR requires Linux kernel version 4.9 or higher[1][9]:

uname -r

Debian 13 includes a kernel version that satisfies this requirement by default (typically version 6.x)[1].

Check the currently available congestion control algorithms[9][10]:

sysctl net.ipv4.tcp_available_congestion_control

Check the congestion control algorithm currently in use[9][11]:

sysctl net.ipv4.tcp_congestion_control

By default, the system uses the cubic algorithm[9][10].

Loading the BBR Module

Manually load the tcp_bbr kernel module[1]:

modprobe tcp_bbr

Confirm that the module has been loaded[1]:

lsmod | grep bbr

You should see output similar to tcp_bbr 20480 0[1].

Configuring sysctl Parameters to Enable BBR

Edit the system configuration file[9][12]:

sudo vi /etc/sysctl.conf

Add the following configuration at the end of the file[9][13]:

net.core.default_qdisc=fq
net.ipv4.tcp_congestion_control=bbr

Save and exit the editor[9].

Advanced TCP Parameter Optimization

For improved network performance, create a dedicated BBR configuration file and add additional TCP optimization parameters[4]:

sudo nano /etc/sysctl.d/99-bbr.conf

Add the following comprehensive configuration[4]:

# BBR Congestion Control Configuration
net.core.default_qdisc = fq
net.ipv4.tcp_congestion_control = bbr

# TCP Buffer Optimization
net.core.rmem_max = 134217728
net.core.wmem_max = 134217728
net.ipv4.tcp_rmem = 4096 87380 134217728
net.ipv4.tcp_wmem = 4096 65536 134217728

# TCP Performance Tuning
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_timestamps = 1
net.ipv4.tcp_sack = 1
net.ipv4.tcp_no_metrics_save = 1
net.ipv4.tcp_moderate_rcvbuf = 1

# Network Stack Optimization
net.core.netdev_max_backlog = 5000
net.ipv4.tcp_slow_start_after_idle = 0

These parameters serve the following purposes: increasing TCP receive and send buffer sizes, enabling window scaling, enabling timestamps and selective acknowledgment, among others[4].

Applying Configuration Changes

Apply the new sysctl settings[9][13]:

sudo sysctl -p

If a separate configuration file was created, use[4]:

sudo sysctl -p /etc/sysctl.d/99-bbr.conf

Alternatively, reload all configurations[4]:

sudo sysctl --system

Verifying BBR Activation

Confirm that BBR has been successfully activated[14][13]:

sysctl net.ipv4.tcp_congestion_control

The output should display[14][13]:

net.ipv4.tcp_congestion_control = bbr

Verify the queue discipline[4]:

cat /proc/sys/net/core/default_qdisc

This should output fq[4].

Check whether the BBR module is being utilized[13]:

lsmod | grep bbr

Performance Testing

Install iperf3 for bandwidth testing[4]:

sudo apt install -y iperf3

Test download speed[4]:

iperf3 -c speedtest.serverius.net -p 5002

Upon completing the above steps, BBR has been successfully enabled on the Debian 13 system, which can significantly enhance network throughput and reduce latency[1][14].

Sources

[1] How To Enable BBR On Debian 13 https://wiki.crowncloud.net/?How_to_enable_BBR_on_Debian_13

[2] How to Enable Google’s TCP BBR (Linux Cloud VPS) https://www.hostwinds.com/tutorials/how-to-enable-googles-tcp-bbr-linux-cloud-vps

[3] New TCP congestion algorithm - BBR https://forum.netgate.com/topic/105502/new-tcp-congestion-algorithm-bbr

[4] How to Enable BBR v3 Congestion Control on Your Linux … https://onidel.com/enable-bbr3-linux-vps/

[5] idroot https://x.com/idr00t/status/1957600526000091428

[6] Bacula and BBR Protocol for Internet Backups, Packet Losses … https://www.bacula.lat/bacula-e-prototoclo-bbr-para-backups-via-internet-perdas-de-pacote-desconecoes-etc/?lang=en

[7] Boost your network speed! Enable BBR on Debian 13 … https://www.facebook.com/CrownCloudHosting/posts/boost-your-network-speedenable-bbr-on-debian-13-to-optimize-tcp-performance-for-/1263433959130983/

[8] How to Boost Linux Server Internet Speed with TCP BBR https://www.tecmint.com/increase-linux-server-internet-speed-with-tcp-bbr/

[9] Enabling TCP BBR on Debian 11 Step-by-Step Guide https://shape.host/resources/enable-bbr-debian-11-improve-web-surfing

[10] Best Way For TCP BBR Setup on Debian 12 https://orcacore.com/tcp-bbr-congestion-control-setup-debian12/

[11] Easily Boost Ubuntu Network Performance by Enabling … https://www.linuxbabe.com/ubuntu/enable-google-tcp-bbr-ubuntu

[12] Boost Your Network Speed with TCP BBR on Linux https://akmatori.com/blog/boost-your-network-speed-with-tcp-bbr-on-linux

[13] How To Enable BBR On RockyLinux 10 https://wiki.crowncloud.net/?How_to_enable_BBR_on_RockyLinux_10

[14] How to Enable BBR on Ubuntu 24.04, 22.04 or 20.04 https://linuxcapable.com/how-to-enable-bbr-on-ubuntu-linux/