code: def get_resources(cls):
          
          ip_controller = IpAddressesController(
              directory.get_plugin())
          ip_port_controller = IpAddressPortController(
              directory.get_plugin())
          resources = []
          resources.append(extensions.ResourceExtension(
                           Ip_addresses.get_alias(),
                           ip_controller))
          parent = {'collection_name': 'ip_addresses',
                    'member_name': 'ip_address'}
          resources.append(extensions.ResourceExtension(
                           'ports', ip_port_controller, parent=parent))
          return resources
docs: Returns Ext Resources.