Taking a network QoS designer's point of view, this paper firstly reviews some of the recent advances on the NCS (Networked Control Systems) design then analyzes its requirements in terms of network QoS guarantees and its capacity to tolerate network performance variation. Current deterministic QoS design approach (including traffic schedulability analysis) may lead to network resource over-provisioning problem since worst-case scenario is often dictated to network QoS designers by the control application. We show that integrated control and network QoS co-design consists in a better solution to this problem. Taking into account the current available results, we see that more research efforts remain to do on control and network QoS co-design and on the development of on-line adaptive QoS mechanisms.