On Fri, May 6, 2022 at 11:23 AM J-P Methot <jp.methot@planethoster.info> wrote:

Hi,

We're in this situation where we are going to move some instances from one openstack cluster to another. After this process, we want our instances on the new openstack cluster to keep the same floating IPs but also to be able to communicate with some instances that are in the same public IP range on the first cluster.

To accomplish this, we want to add static routes like 'X.X.X.X/32 via Y.Y.Y.Y'. However, we're using DVR and when we add the static routes, they do not show up anywhere in any of the namespaces. Is there a different way to add static routes on DVR instead of using openstack router add route ?
-- 
Jean-Philippe Méthot
Senior Openstack system administrator
Administrateur système Openstack sénior
PlanetHoster inc.

I don’t think that there is an automatic way to do what you are trying to do using static routes.

One way to approach this would be to use dynamic routing to advertise the availability of the /32 route.

I just described an approach to this using BGP in another thread on this list with the subject “[ops][octavia][neutron] Distributed Virtual Routing: Floating IPs attached to virtual IP addresses are assigned on network nodes”.

There are several BGP implementations which support this functionality, I believe Neutron Dynamic Routing for OVS works for Wallaby, Juniper Contrail (and probably the Open Source version Tungsten Fabric), and others. The implementation I describe is for OVN, but the same approach could be adapted to other Neutron drivers.

-Dan Sneddon