Comment 2 for bug 1639172

BTW. As far as I know, you can use scheduler hints to implicitly assign fixed IP to a given node:
e.g.:

ironic node-update <id-1> replace properties/capabilities='node:controller-0,boot_option:local'
ironic node-update <id-2> replace properties/capabilities='node:controller-1,boot_option:local'
ironic node-update <id-3> replace properties/capabilities='node:controller-2,boot_option:local'

So you have controller-0, controller-1 and controller-2.

You can modify an example tripleo-heat-templates/environments/ips-from-pool.yaml like below"

parameter_defaults:
  ControllerIPs:
    # Each controller will get an IP from the lists below, first controller, first IP
    external:
    - 10.0.0.251 # scheduler parses controller-0 to index 0
    - 10.0.0.252 # scheduler parses controller-1 to index 1
    - 10.0.0.253 # scheduler parses controller-2 to index 2
    internal_api:
    - 172.16.2.251
    - 172.16.2.252
    - 172.16.2.253
    storage:
    - 172.16.1.251
    - 172.16.2.252
    - 172.16.2.253
    storage_mgmt:
    - 172.16.3.251
    - 172.16.3.252
    - 172.16.3.253
    tenant:
    - 172.16.0.251
    - 172.16.0.252
    - 172.16.0.253