Hello everybody, I’m dealing with http/3 (quic) problems with nginx on SmartOS, has anybody experience with this? Nginx closes http/3 connections over UDP preemtive, with tcpdump I see it happens after they get bigger than 1200 bytes. Network has however (tested) MTU 1500, as it should.

Since there is no way to lower udp packet size with nginx, would it be an approach to dladm create-etherstub, dladm create-vnic, lower mtu there and configure the vnic into the zone?

Or is this the same as the defaul net0 nic in the zone where changing the mtu is not possible?

I suspect you'd need to change it in the vm definition...

it'd be more interesting to understand why nginx is behaving that way -- presumably on other platforms w/ NICs it's not doing that

Unfortunately something like vmadm update bla set nics[0].mtu=1400 does not work…

Maybe I should ask with the nginx guys, but SmartOS is not the typical platform...

true, but i'd imagine they could describe what they're expecting from the NIC for mtu management

I’ll try… thanks.

even if they can't 'fix' it, if we know what they're expecting, someone more familiar with illumos could provide a fix

e.g. if they're using some socket option

or if they're trying to do the equivalent of 'ip a' or such

etc

If I’m lucky I find the one other guy there that tries to run http/3 on nging ON SmartOS :)

i've not looked at the nginx source, so i'm not sure offhand where to look.. it'd take a bit of time to dig through things...

Sure… best would be to find somebody who already has the experience in ths field and knows the (possible) problem.

I'm with @jbk => Knowing what *exactly* is desired/desirable can help. And SmartOS zones are designed around an assumption of possibly-hostile root@zone users.

i did glance at the github source a bit (but not super familair with it) there was nothign that immediately stood out

though as a side note, they appear to be using TCP_CORK on linux (this isn't relevant for QUIC AFAIK) and the equivalent on fbsd, but doesn't appear to use it on illumos

maybe someone more familiar with that might know if it'd be worth adding support...

(e.g. danmcd)

I've seen mentions of TCP_CORK before. Best asked on #illumos, but lemme quickly peek...

We have it, but I have never used it.

(We == illumos)

It's in tcp(4P)!

ahh.. i thought you might have had more experience with it...

like i've heard of it, but never dealt with it

Same here.