ed of wavelength conversion. Last, but not least, another kind of insight into the impact of wavelength conversion can be attained by considering the so-called wavelength reuse factor RW In our case, the wavelength reuse factor is defined as the average number of wavelength paths the node processes divided by the average number of loaded wavelengths per link. If we call Ni,j the number of active wavelengths of the link i,j, and dij is one of (j is a sec- ond index of d) the links that exist between the nodes i and j, N the number of nodes, and Np the number of routed paths, the wavelength reuse factor can be written as (10.29) It is to be noted that Definition (10.37) tries to catch, in a quantitative way, the effect of WCs on the possibility of using wavelengths on links where they could not be used without WCs. But it is a different parameter with respect to the wavelength reuse that is generally defined in literature, in the case of dynamic network dimensioning [48]. The plot resulting from our definition is reported in Figure 10.30 for the example topol- ogy we are using. As intuitive the wavelength reuse factor increases decreasing the number of wave- lengths per DWDM system, since the real connectivity of the system increases (the number of wavelength planes decreases) and increases increasing the traffic up to an asymptote, depending on the considered network. Comparing a situation where the OXC is equipped with WCs on every port and a situ- ation where WCs are not used, we can appreciate the effectiveness of the use of WCs, Next Generation Networking: Enabling Technologies, Architectures, and Performances All WCs No WCs 128 wavelengths 64 wavelengths FIGURE 10.30 Wavelength reuse factor versus traffic Traffic (capacity of routed paths, Tbit/s) for the same networks in Figure 10.29. both in reaching the asymptote at small traffic volumes and in increasing the value of RW. In particular, the smaller the number of wavelengths per DWDM system, the higher the effect of having WCs. 10.3.6 Translucent Optical Ne