Description of problem:

During the live migration between openshift-sdn and OVN Kubernetes, the hybrid overlay br-ext switches are always created with their VXLAN ports using the default 4789 port regardless of whether there is a custom VXLAN port configured for openshift-sdn. This makes the communication between the migrated nodes and non-migrated nodes fail, because both are using different VXLAN ports.

Version-Release number of selected component (if applicable):

Reproduced on 4.16.40, it will likely reproduce in all versions.

How reproducible:

Always.

Steps to Reproduce:

1. Install a cluster with openshift-sdn and custom vxlan port.
2. Upgrade to 4.16.40
3. Start the live migration to OVN-Kubernetes
4. Wait until the target CNI starts being deployed to the nodes (i.e. until the 2nd MCO rollout has started)
5. Optional: Use a pod disruption budget to halt the MCO rollout (which halts the migration) while there are nodes migrated to OVN-Kubernetes and some nodes remain in OpenShift SDN.

Actual results:

Communication not possible between pods on migrated and non-migrated nodes. VXLAN ports different on br0 bridge of OpenShift SDN nodes and br-ext bridge on OVN-Kubernetes nodes.

Expected results:

Same VXLAN port in openshift-sdn and OVN Kubernetes nodes. Communication between pods of both kinds of nodes possible during migration.

Additional info:

Issue found at customer side.