uish different classes of QoS, assuring that each service is delivered fulfilling its specific requirements in terms of delay and packet-ordered arrival at destination. It should perform fault-driven rerouting via the exploitation of the free network capacity; also this algorithm has to distinguish different classes of QoS assuring that each service is protected against failures fulfilling its specific requirements in terms of packet loss and recovery time. It should allow centralized alarm report and failure diagnostic SO as to drive fail- ure repair interventions; this means, among other things, the capability of filtering the alarm chain derived from a single failure SO as to identify the source of failure. It should allow centralized traffic optimization via traffic engineering algorithms in order to optimize the network from the central control room, when needed. It should allow AAA to be performed. Up to now we have listed the requirements of the new control plane. But naturally, since the equipment must be interoperable with legacy TDM technology, the new control plane has to allow this equipment feature. 2.2.4 Summary of Requirements for Next Generation Networks From the previous sections, it is clear that the network evolution is driven by the dif- ficult moment that the telecommunication market is traversing, with a stagnation risk even if the main world carriers have a positive EBIT and the users ask for more and more bandwidth. Since the main structure cost of a telecom carrier is constituted by network OPEX, the main target of the network evolution is to provide enough bandwidth to the end user SO as to enable new services that will boost carrier revenues in pace with a substantial reduction of the network OPEX. Moreover, even if this operation is unavoidably CAPEX intensive, carriers push equip- ment vendors strongly for a price reduction, compatible with their limited CAPEX spending. The requirements discussed in the previous sections have been the guidelines for the network evolution of almost all