I have setup OpenStack with OVS. I have a single Hyper-V server running the controller and three CentOS instances(10.0.0.x) on a private subnet. I created a router in OpenStack with SNAT disabled, as I only want it to route traffic between the private subnet(10.0.0.x) and the external subnet(172.16.1.x)/internet. All of the instances can ping each other along with the external network(172.16.1.x). From the external network, I can ping the interface of the ovs router on the external network. I can not though ping inside the private network. A trace route stops at the IP of the OVS router. With wireshark, I do not see anything coming from the external pc’s IP. If I trace route it, I see packets making all the way to the OVS router and then stop. Since I can ping one way, and not the other; I believe there is something in the router/OVS that is stopping the packets to route into the private subnet. What do I need to look at? (I have disabled all firewalls on all OSes involved.)

Here is a sudo design of the setup.

Does respond to ping

   VM        OVS Router priv int    OVS Router ext int    External PC     

10.0.0.14 ->     10.0.0.1        ->     172.16.1.1     -> 172.16.1.10

Does not respond to ping

External PC    OVS Router ext int    OVS Router priv int       VM

172.16.1.10 ->     172.16.1.1     ->     10.0.0.1        -> 10.0.0.14