Sends ZEBRA_IPV4/v6_ROUTE_ADD message to Zebra daemon.

        :param prefix: IPv4/v6 Prefix to advertise.
        :param nexthops: List of nexthop addresses.
        :param safi: SAFI to advertise.
        :param flags: Message flags to advertise. See "ZEBRA_FLAG_*".
        :param distance: (Optional) Distance to advertise.
        :param metric: (Optional) Metric to advertise.
        :param mtu: (Optional) MTU size to advertise.
        :param tag: (Optional) TAG information to advertise.
        :return: Zebra message instance to be sent. None if failed.

def send_ip_route_add(
            self, prefix, nexthops=None,
            safi=packet_safi.UNICAST, flags=zebra.ZEBRA_FLAG_INTERNAL,
            distance=None, metric=None, mtu=None, tag=None):
        """
        Sends ZEBRA_IPV4/v6_ROUTE_ADD message to Zebra daemon.

        :param prefix: IPv4/v6 Prefix to advertise.
        :param nexthops: List of nexthop addresses.
        :param safi: SAFI to advertise.
        :param flags: Message flags to advertise. See "ZEBRA_FLAG_*".
        :param distance: (Optional) Distance to advertise.
        :param metric: (Optional) Metric to advertise.
        :param mtu: (Optional) MTU size to advertise.
        :param tag: (Optional) TAG information to advertise.
        :return: Zebra message instance to be sent. None if failed.
        """
        try:
            return self._send_ip_route_impl(
                prefix=prefix, nexthops=nexthops, safi=safi, flags=flags,
                distance=distance, metric=metric, mtu=mtu, tag=tag,
                is_withdraw=False)
        except ValueError as e:
            self.logger.exception(
                'Cannot send IP route add message: %s', e)
            return None