On 2026-06-05, Thomas Pries <[email protected]> wrote: > Hi, > > Am 05.06.26 um 00:09 schrieb David Gwynne: >> On Thu, Jun 04, 2026 at 10:52:10AM +0200, Thomas Pries wrote: >>> ... >>> ifconfig ix0/ix1?? hwfeatures ...??hardmtu 9198 >>> ifconfig aggr0?? hwfeatures ...??hardmtu 9198 >>> ... >> OpenBSD is different to most other systems in how it handles packet >> sizes and MTU on interfaces. ... > > Thank you very much for this detailed explanation. > > My network college would be happy, if I could would set the MTU to 9180 > and I tried to set this on aggr0 and ix* via: > > ifconfig ix0 down > > ifconfig ix0 mtu 9180 > > but I always get the error: > > ifconfig: SIOCSIFMTU: Device busy > > What is the procedure to set the MTU?
Set it before attaching the child interface. iirc once you've attached to aggr/trunk you may need to detach before you can change it on the parent.
