NSX-v at VIO-2.5 release supports external network with multiple subnets.
However, this feature requires network admin to configure the physcial router
to route the 2nd subnet CIDR to the OS environment.
In our QA environment, we are not able to configure physical router to route
the 2nd subnet, this test can only be executed at devstack environment.
And ONLY DO:
1. PING to servers' floating-ip
2. SSH sever using its floating-ip
3. From server it can ping other server's private address.
For VIO or other environments, you need to have the right to change physcial
router, and change tempest.conf accoridingly.
3 tests in this module, so run this test sequencially.
Change-Id: I5fc0d137f5b95101bf7b9485a2ca03e61d13d766
fc05b43d32