Open Stack

Was hoping somebody could help me with this. I am trying to set up a
high availability network configuration. From the documentation at:

http://docs.openstack.org/trunk/openstack-compute/admin/content/existing-ha-networking-options.html

I chose option 4 the hardware gateway. However, traffic from the VM
is SNATed on the way out and so has the source IP of the server running
compute.

Inbound traffic works fine, in that the return traffic has the source
IP of the VM.

My nova network configuration is:
# Nova Network Configuration
HOST_IP=172.16.4.11
PUBLIC_INTERFACE=eth2
FLAT_INTERFACE=eth2
FIXED_RANGE=172.16.5.0/24
FIXED_NETWORK_SIZE=200
MULTI_HOST=True

And so all outbound initiated traffic from the VM is SNATed to 172.16.4.11.
Inbound connections, like an SSH login to the VM goes directly to the 
172.16.5.X address assigned by DNSMASQ. 

Any help would be appreciated.
Stuart/