ed, while others are. Naturally, the two paths do not have the same attenuation SO that the OXC power budget depends on the connection inner routing. Let us consider the worst case, and let us assume that the adopted WCs are always those based on SOAs and MZI. The OXC global loss, assuming the matrixes loss equal to 2.2 and 2.5 dB, is 25 dB comprising the margin for patchcords, monitoring couplers, etc. The overall noise factor for the worst case is NFoxc = NF + NF wc + NF2 (10.8) That is 10.8 dB in our case. As far as blocking is considered, blocking probability in this case is not zero, but it should be much smaller than that of the PWP. In particular, a connection request is blocked when, in the presence of a free wavelength in the designated output line, no direct connection is possible and all the WCs are already occupied. So let us start from the probability that a connection request is sent to a WC. Excluding the case of sophisticated routing strategies, it happens when, in the absence of the WC, the request is rejected. Concentrating the attention on one particular wavelength switch, this probability is exactly Pg(N) evaluated in Equation 10.6. If H = 1, the WCs are N, and the probability that all the WCs are occupied is constituted by all the possible combinations of N wavelengths taken among W wavelength plans that need to use a WC since they are in blocking situation. Let us focus the attention on one of the wavelength planes, and let us consider the fol- lowing events: The path that was send to the WCs from this wavelength plane is terminated before the arrival of other potentially blocking requests. The potentially blocking request is directed toward the same output where it is directed to the path that was sent to the WC from the same wavelength plane. The potentially blocking request is directed toward a different output with respect to the path that was send to the WC from the same wavelength plane. Telecommunication Networks In order to evaluate the probabilities of these events in a simplified m