Open Stack

> I am using GRE tunneling and OVS and have several instances working perfectly. They get private IP
> addresses (range:10.0.0.0/24) and get routed through my local IP subnet (192.168.22.0/24) out via 
> my HW router's 192.168.22.1.
> This setup works good and I am pretty happy with it.

>What bothers me is the case where I need to delegate 
>some of our instances a direct public IP address, without 
>the need for 
>any NAT whatsoever.

You can mix GRE and VLAN based networks.
e.g.: 
neutron net-create public --tenant_id $tenant-id --provider:network_type vlan --provider:physical_network default --provider:segmentation_id $vlan-id --shared True

Since this is just a regular VLAN network you can directly patch your router for the segment also in that VLAN and things should work :) 

Cheers,
Robert van Leeuwen