Neutron-dynamic-routing does not work with OVN

[Dr. Jens Harbott]

When using OVN as Neutron backend, announcing prefixes with neutron-dynamic-routing is currently not working due to changes in the database structure. Some attempt to fix this has been made in https://review.opendev.org/c/openstack/neutron-dynamic-routing/+/814055 but wasn't successful.

This is a major stop gap for production deployments which are using BGP to provide connectivity for IPv6 subnets in tenant networks.

[Dmitrii Shcherbakov (dmitriis)]

I believe this issue was addressed in https://review.opendev.org/c/openstack/neutron/+/864051.

However, there are some other considerations around distributed floating IPs with OVN and the extra router attributes in the context of OVN routers relevant to NDR: https://bugs.launchpad.net/neutron/+bug/2022058

[Dr. Jens Harbott (j-harbott)]

Ack, OVN+NDR is working in general now, some specific use case may still need additional work.

[Dmitrii Shcherbakov (dmitriis)]

When it comes to the NDR charm we enabled it in the charms (neutron-api-plugin-ovn specifically needed a code change) documenting those limitations in the charm-guide.

https://review.opendev.org/q/topic:2023-enable-ndr
https://review.opendev.org/q/topic:2023-ovn-ndr

Also we are adding some data plane testing to make sure that the advertised routes are actually possible to reach.

https://review.opendev.org/c/openstack/charm-neutron-dynamic-routing/+/886157