Openstack instance is unreachable

I am facing the following issue with my new Openstack installation. The installation is a little bit weird and to elaborate more, I have a controller and a compute node running as VMs in XenServer. The compute node has nested virtualization enabled and uses qemu in order to provision VMs. I have a provider flat network that has a public range of IPs and VMs use this network. I am able to create instances and access them via console, but I can't ping them or ssh even if they have public IPs. I am not very familiar with Xen Server, is there any configuration that is needed (bridges, promisc mode, etc)? -- *George Papathanail* *Associate Researcher* *Department of Applied Informatics* *University of Macedonia*