erformances IM - SNo=17db SNoi = FIGURE 10.26 Penalty versus the header bit rate for both DPSK and IM modulation of the header signal and for different values of Header bit-rate (Mbit/s) the signal SNoi. For simplicity = . To understand the situation with a realistic example, let us assume R = 10 Gbit/s and SNoi ;=17dB. The penalty versus the header bit rate is shown in Figure 10.26 for both DPSK and IM modulation of the header signal, for different values of the signal SNoi, and assuming for simplicity, = From the plot, it is clear that if the penalty is to be contained within 1 dB, the header bit rate should not exceed a value comprising between 25 and 100 Mbit/s. This signaling transport method is interesting for the freedom that it gives to the designer to include information in the OCh head, but it is affected by the penalty on the data car- rying signal and by the need of having a data rate decoder also, when only the header has to be read. 10.3.4 Design of a Transparent Optical Network: ILP Optimization By its definition, the T-OTN is a static switched network; thus, a method based on integer linear programming (ILP), similar to that adopted for static networks in Chapter 8, seems more appropriate for its design. Nevertheless, there are significant differences between the dimensioning of a network based on DWDM transmission and electrical switching and the dimensioning of a T-OTN. We will not derive all the ILP equations for the transparent network dimensioning, as we have done in Chapter 8, for the case of an "opaque" network. We will, instead, point out the differences between the two dimensioning problems SO that deriving the equations becomes only a formal problem. 10.3.4.1 Integer Linear Programming to Dimension Transparent Optical Transport Networks The hypotheses at the base of this static optimization approach are stated in Chapter 8 as follows: The infrastructure is completely given; that means that geographical position of Points of Presence of the carrier and of fiber cables are given. We will w