Description of problem: During deployment, the overcloud nodes will check reachability of the Undercloud by pinging the undercloud. If the ping test works, but port 8775 is not reachable on the Undercloud, then the deployment will hang. We should check to see if TCP port 8775 is reachable, not just if the IP is pingable. Version-Release number of selected component (if applicable): OSP 10 GA How reproducible: 100% Steps to Reproduce: 1. Configure Undercloud 2. Deploy Overcloud Actual results: If port 8775 is not reachable for some reason (firewall, etc.), then the deployment will hang. Expected results: An error should be given that helps to diagnose the root cause. Additional info: I think we can use the "nc" tool from within tripleo-validations to validate that port 8775 is reachable from the Overcloud.