Using BBR in a network namespace

[rukz...@gmail.com]

Hi,

I have a network namespace (with veth) and enabled the BBR as follows.

net.ipv4.tcp_congestion_control=bbr

My question is since veth does not support net.core.default_qdisc=fq will BBR work as it is supposed to inside a network namespace? My Linux version is 5.15.1. 

Thank you!

Best,

Rukshani 

[Neal Cardwell]

Hi,

Using BBR inside a network namespace should work just fine. A few thoughts:

+ For Linux kernel versions v4.20 or later (including your Linux version, 5.15.1), you don't need to use the fq qdisc with BBR. If there is no fq qdisc in the transmit path then the Linux TCP stack will detect that and use TCP-internal pacing. So you don't necessarily need to use net.core.default_qdisc=fq for BBR.

+ If you still want to use fq, then you should be able to use fq with a veth device. In fact you can see there is a testing script in the BBR github distribution here that uses veth with fq (fq is set up for a veth device in this line).

best regards,

neal

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[Rukshani Athapathu]

Thank you so much for the info! 

Best,

Rukshani