Fair traffic queueing using fq_codel

08.08.2013 by Dirk Olmes

I’ve been planning on playing around with Linux’ traffic shaping for quite some time now. My linux router machine is directly connected to the DSL modem - no consumer grade router box in the mix (and hence none of the vulnerabilities and security nightmares that have been discovered in those kind of boxen in the recent past).

My requirements for traffic shaping are quite simple: I share some open source downloads via bittorrent but I don’t want the torrent traffic to block regular surfing, Skype voice calls etc.

Yesterday, my friend Holger brought the Codel packet scheduler to my attention. Wikipedia has a good explanation of the Codel algorithm.

Since Codel is “no knobs”, “just works” all you have to do is to enable CONFIG_NET_SCH_FQ_CODEL in the kernel config and enable codel using

tc qdisc add dev ppp0 root fq_codel

What can I say? I just works. I have turned off throttling on the torrent uploads and did not notice any lag in daily surfing. Skype calls sound like they did before with torrents turned off.

I realize that fq_codel is not for everyone (i.e. if you use a consumer grade router box you’re SOL) but it definitely helps with my use case.



Dirk Olmes

Posted on 12.05.2015

You can go even one step further and make the codel packet scheduler the default one for all network connections. Just use sysctl -w net.core.default_qdisc=fq_codel

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