monitoring of the signal characteristics and, if needed, can constitute a branching point for the transmission system. 10.3 Transparent Optical Transport Network When the revolution related to optical transmission hit the market, it seemed that optics was on the edge to completely substitute electronics in the telecommunication network. On the wave of this forecast, the original idea of transparent optical transport network (T-OTN) was born [5]. At the very beginning, the T-OTN was conceived as a whole geo- graphical transport network without any regeneration point, only constituted by analog transmission systems and analog OXCs. At the edge of this network, there were the electronic edge machines that were used for signal conditioning and interface with local and access networks. This idea is shown in Figure 10.9, and one of the first transparent OXC architectures that was proposed is shown in Figure 10.10. Optical transparent network Electronics machines Optical transparent cross-connect FIGURE 10.9 Scheme of an optical transparent transport network. Telecommunication Networks 11 Switch 12 Switch 13 Switch Local channels Local channels FIGURE 10.10 Architecture of one of the first proposed transparent OXCs firstly introduced in the framework of the EU project MWTN (Multi Wavelength Transport Network). (After Iannone, E. and Sabella, R., IEEE J. Lightwave Technol., 14(10), 2184, 1996, where the references where this OXC was introduced for the first time can be found). The expected advantages of the transparent optical architecture were as follows: Bit rate, format, service transparence: This means that completely different signals were conceived coexisting on different wavelengths [6]. Low power consumption: On the assumption, that is still valid, that analog optics consumes less power to switch with respect to digital electronics [7]. Almost infinite bandwidth: Due to the huge bandwidth of optical fibers that also assures that the network is future proof. CAPEX sparing: Based on a forecast of enormous growth of