Openstack deployment documentation unclear about how the nodes are SSH into by the Director system when there is no operating system installed on any of the overcloud nodes

Issue

• We are following the documentation steps to deploy a production Openstack environment, however, some parts of it are not very clear.
• We are setting the instackenv.json file with the pm_type value set to pxe_ssh, however, it's hard to understand how the director would access to that node via SSH when that node does not have the operating system installed, besides that, if we setup the instackenv.json like this:

            "mac":[
                "00:xx:xx:xx:xx:xx"
            ],
            "cpu":"1",
            "memory":"6144",
            "disk":"79",
            "arch":"x86_64",
            "pm_type":"pxe_ssh",
            "pm_user":"root",
            "pm_password":"$(cat /home/stack/virtkey)",
            "pm_addr":"192.0.2.205"

• When the host boots it does not gets that IP address.