Vlan tagging

Note that Libvirt always supported this functionality for Open vSwitch bridges: https://libvirt.org/formatdomain.html#setting-vlan-tag-on...

I don't know whether the newly introduced Linux bridge support creates the necessary per-VLAN bridge devices for you. Probably not. I wouldn't be surprised if this feature required the VLAN-aware flavor of Linux bridges and didn't work at all with "traditional mode" Linux bridges (those that require a separate bridge device per VLAN).