The book outlines the current state of the telecommunications network and the different alternatives for its evolution. The author systematically reviews the network design problem and underlines the links between different aspects. This reference presents the engineering knowledge needed to construct a network evolution strategy. It examines the elements influencing telecommunications network evolution and their interdependence, and it provides a complete review of the architecture alternatives. Content ranges from high-level architectural elements to component physics, with a focus on solving the same problem from different points of view.