Description of problem: Changing the vlan of a physnet does not update the vlan of the external networks defined on top of it. It's a known issue that deserve a clear bug. Version-Release number of selected component (if applicable): 4.2.3.2-0.1.el7 How reproducible: 100% Steps to Reproduce: 1) Create new physnet network(data center network) with vlan 162 2) Attach the physnet network to the host 3) Create new ovn network + choose create on external provider + choose the data center network(physnet network) from step 1^^ without subnet 4) Run VM with ovn network vNIC - VM got IP from vlan 162 5) Shutdown the VM 6) Edit the physnet network with new vlan tag 163 - All changes applied successfully on the host 7) Start VM - Result - VM got IP from vlan 162 and not vlan 163 * NOTE - The exact same flow, with regular vlan network(no ovn involved) working as expected. Actual results: The physnet vlan wasn't updated Expected results: The physnet vlan should be updated Additional info: See also BZ 1534565
An alternative way to fix would be to unlink the oVirt's OVN network entity from the physnet network, instead of update the OVN network's `provider:segmentation_id` as suggested in comment 0.
Another alternative would be to forbid to change the VLAN ID, if engine knows that the physical network is used as physnet by an external network.
I prefer the simpler solution proposed in comment 1, but we are unlikely to address it before we hear a demand from the field for physnet, which would occur only after bug 1195208 is out.