Can't ping instance from controller or any other external hosts but can ping from compute node
I'm deploying mitaka on 2 nodes which is controller and compute. the problem is I can't ping instance from controller or any external host except for compute node where I can ping the instance well. from the instance I can ping the gw and even the controller or other host but not the other way around I used tcpdump when ping from instance to controller and everything is ok. when ping form controller to instance, instance reply its mac-add to controller but did not reply icmp packet from controller. I also added rules for icmp in openstack but it didn't work. figured out there is something blocking the instance from replying the icmp packet. I also looked for iptables and that's not much help either.
anyone has any suggestion ? I will appreciate that been struggling with this for weeks.
I will post any output if you need