I'm wondering if the ARP requests should be tagged when being sent out of a VLAN tagged interface?
It seems logical to me that the ARP request should be tagged, since it needs to travel all the broadcast domain. If any switches or devices in the broadcast domain have VLAN configurations, the untagged ARP request will not pass.
I would assume that they should, but I don't have any references to confirm.
Best Answer
Whether the frame is ARP or not is irrelevent. Anything sent out a trunk port is tagged with the VLAN the frame is a member of:
ARP is sent by the client, the client typically has no knowledge of what VLAN it is a member of. It is therefore unable to add a VLAN tag, and shouldn't be expected to. The ARP the client sends will arrive on the switch untagged.
If the switch sends the frame out a trunk port, the switch will add a VLAN tag.