def _get_default_route(version, subnet):
    """Get a default route for a network

    :param version: IP version as an int, either '4' or '6'
    :param subnet: Neutron subnet
    """
    if subnet.get('gateway') and subnet['gateway'].get('address'):
        gateway = subnet['gateway']['address']
    else:
        return []

    if version == 4:
        return [{
            'network': '0.0.0.0',
            'netmask': '0.0.0.0',
            'gateway': gateway
        }]
    elif version == 6:
        return [{
            'network': '::',
            'netmask': '::',
            'gateway': gateway
        }]