 than ten, we can assume to use a 2D MEMs switch. Looking at Table 5.8, we can assume a power consumption of 20 mW per switch with a switch crossing loss of as = 4 dB. Thus, the traversing loss of the PWP is Apwp = 18 dB, where the AWGs are considered to lose 5 dB each and a certain margin has been allocated for the backplane, the patchcords, and SO on. As far as the amplifiers are concerned, the situation is analogous of a two stage amplifier with a great interstage loss. It seems not opportune here to perform the optimization of the amplifier chain, not to deduce a result too dependent on amplifier parameters. It seems more reasonable to adopt a simpler solution, that is, assuming that the amplifier at the output compensates the losses of the span after the OXC, which will be L km long, while the amplifier at the input is used to compensate the OXC losses. In this way, the OXC appears from the transmission point of view not more than an exceptionally noisy amplifier. At the end, calling a the fiber attenuation, the gains G1, G2 of the pre- and post-amplifiers are (10.3) G2=aL (dB) Moreover, we have to take into account that the output amplifier also has to host the DCF that has to compensate the dispersion of the fiber span following the OXC. Thus, it is rea- sonable to assume that the input amplifier is single stage with a noise factor NF1=5dB, while the output is double stage with a noise factor NF2 = dB. At this point, we can write (10.4) The switch fabric is wavelength but not fiber modular, and it is also not latching due to the chosen switching technology. Since we have 90 switches, the power consumption is 1.8 W for the switch fabric, plus the control electronic and the drivers that we assume to burn 500 mW for a complete estima- tion of the switch fabric power consumption. Passing to the inner connectivity, we will start from the hypothesis already done in Chapter 7 that the network manager fix a minimum time interval between the arrival of two connection requests to the same OXC. From Chapter 7 we also