Hello Jiatong:

If you are using a VLAN network to create the SR-IOV ports on it, Nova will assign the corresponding VLAN ID to the VF. The traffic inside the VM won't have the VLAN header but it will be tagged when egressing the VF. This is the same as a tagged OVS TAP port.

If you are talking about VLAN trunking, ML2/SR-IOV mechanism driver does not support it. Each vendor and model would require a different implementation. There was some years ago an attempt to implement it in Neutron [1]. If you are willing to continue this implementation (maybe with another driver), I'll help you with this. I don't know if this is what you are looking for.

Regards.

[1]https://review.opendev.org/c/openstack/neutron/+/665467

On Mon, Mar 10, 2025 at 3:10 PM Jiatong Shen <yshxxsjt715@gmail.com> wrote:

Hello Experts,

I am learning using SR-IOV to enable faster network access. I do not
have a smartNIC so I am only talking about regular VF device
passthrough. Right now, I configure Nova and use regular device
passthrough flavor to create an instance. It works but since the PF
device is a trunk network port, I have to configure sub interface
manually in the guest.

I find that I can only use neutron to configure SR-IOV VF devices
(bandwidth, spoofcheck etc.). I am not trying it yet but I would like
to ask if I use SR-IOV through neutron, does neutron's sriovagent will
configure vlan id automatically such that I do not need to configure
it inside the guest? if answer is yes, could you show me the related
code? Thank you for your help.

--

Best Regards,

Jiatong Shen