ction remains a key for success [20]. 2.2.2 Requirements for Next Generation Equipment The profound transformation in the telecommunication business caused by the Internet revolution, market liberalization, and the post-bubble crisis has a huge impact on technical aspects. In the following sections, we will summarize the main impacts in terms of changes telecommunication network requirements. In the telephone-centric period, the telecommunication network was constituted by superimposed and separated networks. The most important of these superimposed networks, generating the main part of car- rier revenues, was the telephone network. The telephone network was built on a few key elements: Deterministic TDM transmission Call-based circuit switching Very fast protection in the core area (less than 50 ms of protection time end-to-end) Very high availability (99.999% that means less than 5 min out of work in a year) The control plane of such a network, in its most advanced version, was provided by a cen- tralized software control that was able to monitor both equipment and network (e.g., TDM streams exploitation efficiency) and incorporated algorithms for network reconfiguration and upgrade. Besides the telephone network, there were also other logically distinct networks that exploit the same set of transmission systems intended to provide data services mainly to business customers. Generally, such networks used ATM or frame-relay protocols and were characterized by a very high availability (required by business customers) and high security. The control plane of such networks were completely separated by those of the telephone network, being the monitoring and configuration of the common transmission systems operated by a dedicated control plane. Drivers for Telecommunication Network Evolution A similar structure is suitable if data traffic is quite a small portion of the overall traffic and data users are well separated by standard telephone users, but it becomes very inef- ficient if the main part of the traffic is c