ered an example of a switch fabric of a global capacity of 5 THz switching 10 Gbit/s channels and we have evaluated a total power consumption of 1.4kW. Distributing the fabric on 10 cards of an ATCA platform (the sub-rack holds 12 cards and we assume that two of them are used for control), we have a power consumption of 140W per card. This is compatible with the ATCA standard, but gives an idea of the high power consump- tions of large electronic switches. Moreover, in packet switching applications, the line cards have also different functional- ities with respect to pure transmission and detection of the signal. Generally, input queues and the first header processing are located in the line card, SO that a standard line card of an IP router has a power consumption much higher with respect to a DWDM transponder, using the same transmission technology. Regarding the backplane, the key point is that, different from DWDM systems, the sig- nal itself have to propagate on the backplane to connect one switch fabric card with the other and to pass from the line cards to the switch cards and vice versa. If the switch processes signals at 10 Gbit/s, this means that the backplane has to transmit signals at that speed, requiring a technology completely different from that of DWDM backplanes. 7.5.1 Fast Backplanes for Switching Equipment Since DWDM backplanes are generally based on parallel busses, in principle, it should be possible to increase their capacity by increasing the number of parallel lines constituting the bus. In practice the number of parallel lines that can be incorporated in a backplane is limited by several elements: Increasing the number of lines the interference also increases and shielding prob- lems are harder and harder. The cost increases linearly with the number of parallel lines, since this is the way in which increases the number of transmitters and receivers needed to implement the bus, while using serial high-speed transmission the cost increases much less than linearly with the bit rate. The num