I am wondering if I can deploy OpenStack with keystone, nova, cinder and glance modules, without installing neutron module. Let's say we have a pool of IPs from an external source and we want to assing IPs from this pool to the instances launched in Nova. Is that possible?

It would be something like:

nova floating-ip-associate <instance> <ip_from_external_source>

Once the instance is terminated, what would happen with the IP assigned to the instance?

Thank you for your help.