From the redhat docs found here: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux_OpenStack_Platform/7/html-single/Director_Installation_and_Usage/index.html#sect-Using_the_Native_VLAN_on_a_Trunked_Interface (https://access.redhat.com/documentati...)

You can configure the native vlan to use the trunked interface for your deployment. Obviously, the native vlan will need to be the Provision interface.

The director uses this network traffic type to deploy new nodes over PXE boot and orchestrate the installation of OpenStack Platform on the Overcloud bare metal servers.  This network is predefined before the installation of the Undercloud.

.

F.4. USING THE NATIVE VLAN ON A TRUNKED INTERFACE

If a trunked interface or bond has a network on the native VLAN, the IP addresses are assigned directly to the bridge and there will be no VLAN interface.
For example, if the External network is on the native VLAN, a bonded configuration looks like this:

network_config:
  - type: ovs_bridge
    name: {get_input: bridge_name}
    dns_servers: {get_param: DnsServers}
    addresses:
      - ip_netmask: {get_param: ExternalIpSubnet}
    routes:
      - ip_netmask: 0.0.0.0/0
        next_hop: {get_param: ExternalInterfaceDefaultRoute}
    members:
      - type: ovs_bond
        name: bond1
        ovs_options: {get_param: BondInterfaceOvsOptions}
        members:
          - type: interface
            name: nic3
            primary: true
          - type: interface
            name: nic4