ctronic wavelength conversion and regeneration are performed in the nodes. We will also assume that partial equipment failures are all managed with redundancy at the equipment level; the only equipment-related failure we will consider will be complete node failure. Realistic core networks are generally constituted by a mesh layer 0 topology with a con- nection degree between 2 and 2.5. A connection degree greater than 2 is needed to imple- ment effective survivability strategies, but a too high connection degree is avoided due to the high cost of installing in the field long cable ducts to create connections between far nodes. We will assume as test network a reduced version of the network of Figure 3.2, which is shown in Figure 8.25. Some nodes are eliminated from the real network both to rise the connection degree (in the real network there are also apparently single connections that are in reality doubled by parallel cable ducts deployed along different routes) and to lower the complexity of ILP design reducing to 10 the number of nodes. We will carry out the survivability performance evaluation in two steps: 1. The network is designed using the ILP procedure with a target traffic matrix. The design is performed in two steps: first the design of a network without survivabil- ity, then in a second phase equipments and transport capacity is added to allow the chosen survivability strategy to be implemented. Normalized cost parameters for the network design are summarized in Table 8.7. 2. Once the network is dimensioned and loaded, a simulation of different failure scenarios is performed SO to assess the capability of the chosen survivability strat- egy to react. This simulation is a discrete time slot simulation, where the evolution in time of the network behavior is simulated starting from the instants in which a failure event happens. These instants are randomly generated. In this way it is possible also to evaluate correctly parameters like the availability that imply the knowledge of the failure and repair p