send_ack(struct neighbour *neigh, unsigned short nonce, unsigned short interval)
{
    int rc;
    debugf(BABEL_DEBUG_COMMON,"Sending ack (%04x) to %s on %s.",
           nonce, format_address(neigh->address), neigh->ifp->name);
    rc = start_unicast_message(neigh, MESSAGE_ACK, 2); if(rc < 0) return;
    accumulate_unicast_short(neigh, nonce);
    end_unicast_message(neigh, MESSAGE_ACK, 2);
    /* Roughly yields a value no larger than 3/2, so this meets the deadline */
    schedule_unicast_flush(roughly(interval * 6));
}
send_ack(struct neighbour *neigh, unsigned short nonce, unsigned short interval)
{
    int rc;
    debugf(BABEL_DEBUG_COMMON,"Sending ack (%04x) to %s on %s.",
           nonce, format_address(neigh->address), neigh->ifp->name);
    rc = start_unicast_message(neigh, MESSAGE_ACK, 2); if(rc < 0) return;
    accumulate_unicast_short(neigh, nonce);
    end_unicast_message(neigh, MESSAGE_ACK, 2);
     
    schedule_unicast_flush(roughly(interval * 6));
}