RDO Stack:VMs cannot access external network.

Issue:

There are many root causes to make your openstack vm instances cannot be reached from external network. But one of them in my case is VMs and Host (Openstack host) can only ping each other successfully; others are all failed, including vms cannot ping any
outside IP addresses.

Solution:

In this case, you could check if your network card configuration supports Promiscuous mode.

You can set it by simply adding following pair-value into ifcfg-* file and reboot your node.

PROMISC=yes