If I understand your question correctly, you want Floating IPs to be attached directly to the instance rather than the private Fixed IP address?

If so, this is possible. In Neutron, the easiest way to do this is to make your public / external network shared (--shared). Be aware, though, that this will allow anyone to launch an instance on the public network. You might exhaust your public IP range quickly.

It also might conflict with L3 services in Neutron. I tested this scenario a few months ago but found I ran into difficulties when introducing Security Groups and L3 services. The core functionality, instances having a public IP directly on their virtual NIC, worked, though.

Neutron does not auto-create floating IPs or auto-assign them to new instances but this feature is planned for future inclusion. Source: http://openstack.redhat.com/Floating_...