Hi Erik, Thanks for the quick response!
Just FYI there's no reason you need to use DVR with OVS. You could run vanilla OVS with L3-HA and Octavia Amphorae work great and do proper failover. Is DVR a requirement? I don't have any issues with allowed-address-pairs and OVS but I've never tried to mix in DVR.
I guess I hadn't thought of not using DVR. The benefit seemed significant back in the day, and I thought it was required for VXLAN configurations, but maybe not? I guess that all traffic that is sent to a router would go through a centralized router instead, which, I think means that all floating IP traffic would flow through network nodes (where the centralized routers are located). I will review and report back what I find since it has been a while since I looked into this.
Using Amphorae with an OVN fabric should still work fine. They are VMs and don't really care what they attached to so long as Neutron responds to the appropriate requests. The OVN Octavia driver has the benefit of native load balancers without VMs, but you are correct that you'd lose your L7 functionality.
I suspected that it should, theoretically, but I didn't know if anyone had experience with this before we attempt it. Maybe three is a way to determine which load balancer type is chosen using Octavia, OVN or Amphorae. Eric