Where is this qdisc coming from?

Hello forum,

my wired connection (Ethernet) is sometimes mysteriously giving up. The hardware is all fine (I checked ethernet port, cables, switch, router). I found this mysterious traffic control qdisc:

> sudo tc qdisc show
qdisc fq_codel 0: dev enp1s0 root refcnt 2 limit 10240p flows 1024 quantum 1514 target 5ms interval 100ms memory_limit 32Mb ecn drop_batch 64

NetworkManager might do it, though it would be strange for it to configure a limit by default. To date my Ethernet NetworkManager connection didn’t have a qdisc configured:

> nmcli connection show Ethernet | grep tc.qdiscs
(no output)

I have now configured a qdisc in NetworkManager per RedHat docs:

> nmcli connection modify Ethernet tc.qdiscs ‘root pfifo_fast’

While this is indeed applied successfully (as tc qdisc show shows), I yet have to see if the connection drops gone for good.

Still, where is the default limited qdisc coming from?

Happy hacking!

Isn’t fq_codel the kernel default?

Also not sure why congestion control would have any effect on a wired connection “giving up”. :thinking: