Comment 1 for bug 1808062

Note that it appears that NSX-T has a concept called "Transport Zones" that enables the feature that is being requested here. Compute nodes within a given transport zone will only be able to communicate with compute nodes within that same transport zone. This prevents network traffic from being sent between zones. More information here:

https://docs.vmware.com/en/VMware-NSX-T-Data-Center/2.3/com.vmware.nsxt.install.doc/GUID-F47989B2-2B9D-4214-B3BA-5DDF66A1B0E6.html

NSX-T also supports Availability Zones, but it appears that those are separate from the Transport Zone functionality:

https://docs.vmware.com/en/VMware-Integrated-OpenStack/5.0/com.vmware.openstack.admin.doc/GUID-37F0E9DE-BD19-4AB0-964C-D1D12B06345C.html

It's possible that limiting tunneling traffic to a particular AZ may be outside the intended functions of Neutron AZs, but I think this is a valid use case.