'Check items in configuration files.
Check for required and invalid configuration items.
The actual values are not verified for correctness.'

def _check_config_params(self):

    if (not self.conf.interface_driver):
        msg = _LE('An    interface    driver    must    be    specified')
        LOG.error(msg)
        raise SystemExit(1)
    if self.conf.ipv6_gateway:
        try:
            msg = (_LE('%s    used    in    config    as    ipv6_gateway    is    not    a    valid    IPv6    link-local    address.'),)
            ip_addr = netaddr.IPAddress(self.conf.ipv6_gateway)
            if ((ip_addr.version != 6) or (not ip_addr.is_link_local())):
                LOG.error(msg, self.conf.ipv6_gateway)
                raise SystemExit(1)
        except netaddr.AddrFormatError:
            LOG.error(msg, self.conf.ipv6_gateway)
            raise SystemExit(1)
