I am trying to setup the 3-node (controller, neutron and compute) openstack configuration on 3 Virtual machines running on Virtualbox. I have enabled promiscous mode on the external network as suggested in the manual. In the verify connectivity step - here ( http://docs.openstack.org/juno/install-guide/install/apt/content/neutron_initial-networks-verify.html (http://docs.openstack.org/juno/instal...) ), it says that "you should be able to ping the IP address of the tenant router gateway from any host on your external physical network." I am able to do that from the controller and compute nodes which are on the physical network. But when I try to do that from the network node (which has the tenant router on it) , it cannot ping it. Does this mean that there is an error in my setup ? If so, any pointers on how to troubleshoot it would be very welcome.

Edit 1 in reply to response - After configuring the network node as mentioned in the manual, I am able to launch an instance, but the network node no longer connects to the external network and so the instance is not able to as well. I have read through similar discussions on this forum and elsewhere but could not find a clear solution. I think I am not bridging the interfaces as they should be bridged. I am including my /etc/network/interface file of the network node as well as the outputs of some of the network-related commands that are often asked in such situations.

Configuration Detail - 3 VM's running Ubuntu 14.04 on VirtualBox. The management and tunnel networks are on eth1 and eth2 and are configured as internal networks. Static ip's are set on 10.0.0/24 and 10.0.1/24 respectively. The external network is on eth0 and is configured using the NatNetwork adapter that Virtualbox provides. ( https://www.virtualbox.org/manual/ch06.html#network_nat_service (https://www.virtualbox.org/manual/ch0...) ) . Basically the host and guests can see each other and the guest machines can access internet using the host (similar to NAT adapter in that aspect.). This works on the compute and controller nodes and used to work on the network node before I configured neutron setup on the network node. I set a static ip on this in the 192.168.16/24 subnet. A part of this is used for the virtual external network on the neutron node.