The release notes [0] for the ``enable-chassis-as-gw`` states that the feature is optional and that if no chassis has the flag set a chassis with appropriate bridge mappings will be selected.
This works almost as advertised and connectivity from an instance out to the external network works, I can also confirm that when I add a floating IP the source address traffic flowing out from an instance changes to the floating IP.
However, traffic initiated from the external network to the floating ip destined for the instance is not forwarded.
Adding the ``external-ids:ovn-cms-options="enable-chassis-as-gw"`` to the gateway and then re-creating network resources and instance resolves the issue.
I'll try to dig for what exactly is going wrong, it's probably just one check that assumes the enable-chassis-as-gw flag is required when it in reality is not.
0: https://github.com/openstack/networking-ovn/blob/93834508d1795846ffcda2cc179e8b02ebc8ce85/releasenotes/notes/ovn-cms-options-enable-chassis-as-gw-3adc7024478e3efa.yaml
Fix proposed to branch: master
Review: https:/