s. The first algorithm, introduced by [46] can be described as follows: A flag is set to determine if regenerators can be used if needed to decrease the network cost or not. The initial path routes are found using the Dijkstra algorithm [35]. Every path is analyzed from a transmission point of view; if a path is not accept- able, either the corresponding request is rejected or an electrical regenerator is added to the OXC at half the path to regain transmission quality. The choice depends on the flag set at the beginning of the algorithm. Next Generation Networking: Enabling Technologies, Architectures, and Performances The maximum link set is determined: the links belonging to this set are called maxi- mum links, and correspond to those links that support the maximum number of paths. The paths crossing the maximum number of maximum links are rerouted: this rerouting aims at making lower the cardinality of the set. For each link, the number of unused wavelengths is evaluated, and the set of the most inefficient links is found. This set consists of those links characterized by the highest waste of frequencies. The paths containing the maximum number of inefficient links are found: these paths are the candidates for the rerouting. The paths individuated in the previous step are rerouted using again a Dijstra algorithm with a link weight Wii for the link from node i to node j. The weight depends on the parameter Cii = Pij Mod(W) where Pij is the number of wavelength paths accommodated in the link and W is the number of wavelengths per DWDM system. The meaning of Cii is clear: it is the number of utilized wavelengths of the DWDM system that is not fully loaded, running along the considered link. The particular expression of the weight is if Ci,j = 0, otherwise Every path rerouted in the previous step is analyzed from the transmission point of view. If the new path is not acceptable, either it is not rerouted (if regen- erators are not selected as possible network elements) or two solutions are con- sidered from the c