Neutron NAT Gateway Not Working

Issue

• We have an application that launches VMs for end users on OpenStack so they can access a large HPC cluster. This application requires access to several services outside of OpenStack such as LDAP and license servers for a newly launch VM. Once a VM becomes fully accessible from the private OpenStack network at the completion of cloud-int our application will assign floating IP to the VM. The problem that we are having is that the VM cannot reach outside the private OpenStack IP space until a floating IP is assigned. We are using Neutron distributed virtual routing (DVR). When using DVR the controllers will do the NAT routing if a floating IP is not assigned.

• The problem may be a routing issue on the controller nodes where wrong VLAN is being used to forward the packets.