T5489: Change default qdisc from 'fq' to 'fq_codel'

[Apachez-]

Change Summary

Default qdisc should be "fq_codel" rather than "fq" with "bbr" as congestion control in modern Linux kernels.

This is a followup on #2224

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5489

Related PR(s)

• T5489: Add sysctl TCP congestion control by default to BBR #2224

Component(s) name

sysctl

Proposed changes

Change following parameters in src/etc/sysctl.d/30-vyos-router.conf from:

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

to:

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

Ref:

https://www.bufferbloat.net/projects/codel/wiki/

Either qdisc can be enabled by default via a single sysctl option in /etc/sysctl.conf:

net.core.default_qdisc = fq_codel - best general purpose qdisc

net.core.default_qdisc = fq - for fat servers, fq_codel for routers.

Also thread in https://forum.vyos.io/t/bbr-and-fq-as-new-defaults/12344/10

How to test

After install/upgrade verify default settings through:

# sudo cat /etc/sysctl.d/30-vyos-router.conf
...
# Congestion control
net.core.default_qdisc=fq_codel
net.ipv4.tcp_congestion_control=bbr

or:

vyos@vyos:~$ sudo sysctl -a | grep net.core.default_qdisc
net.core.default_qdisc = fq_codel

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[c-po]

@Mergifyio backport sagitta

[mergify]

backport sagitta

✅ Backports have been created

• #2350 T5489: Change default qdisc from 'fq' to 'fq_codel' (backport #2349) has been created for branch sagitta