def _host_dhcp_opts(vif_id=None, gateway=None):
    values = []
    if vif_id is not None:
        values.append(_host_dhcp_network(vif_id))
    # NOTE(vish): 3 is the dhcp option for gateway.
    values.append('3')
    if gateway:
        values.append('%s' % gateway)
    return ','.join(values)
Return an empty gateway option.
dataset/ETHPy150Open openstack/nova/nova/network/linux_net.py/_host_dhcp_opts