Comment 2 for bug 1744622

Actually it raises InvalidIPv4Address exception before I chang code in https://github.com/openstack/ironic/blob/master/ironic/dhcp/neutron.py#L157 to Line 163
which is:
if ip_address:
    if netutils.is_valid_ipv4(ip_address):
        return ip_address
    else:
        LOG.error("Neutron returned invalid IPv4 address %s.",
                   ip_address)
        raise exception.InvalidIPv4Address(ip_address=ip_address)

then begin to create pxe config named by one IPv6 address in function https://github.com/openstack/ironic/blob/master/ironic/common/pxe_utils.py# L246 .

Create pxe config named by interface mac works good. If host boots from UEFI pxe over IPv6 network, mac of its boot interface is 11:22:33:44:55:66, bootloader file BOOTX64.EFI got from centos7.4.ISO/EFI/BOOT directory will first load file named 'grub.cfg-11-22-33-44-55-66-'