illey, R.I., Watts, P.M., Glick, M., Bayvel, P., Electronic dispersion compensation by signal pre- distortion. In Proceedings of the Optical Fiber Communications Conference OFC 2006, Paper OWB3, IEEE/OSA, s.l., 2006. Laurencio, P., Medeiros, M.C.R., Analysis of optical single side band systems employing optical amplifiers. In The International Conference on "Computer as a Tool", EUROCON, 2007, IEEE, s.l., pp. 1017-1022, 2007. 45. Takano, K., Sakamoto, N., Nakagawa, K., SPM effect on carrier-suppressed optical SSB trans- mission with NRZ and RZ formats, Electronics Letters, 40(18), 1150-1151 (2004). 46. International Electrotechnical Commission (IEC), Basic dimensions of front panels, subracks, chassis, racks and cabinets, IEC 60297-3-101, 1st edn., 2004-2008. 47. International Electrotechnical Commission (IEC), Subracks and associated plug-in units, IEC 60297-3-101, 1st edn., 2004-2008. 48. International Electrotechnical Commission (IEC), Injector/extractor handle, Keying and align- ment pin, Connector dependent interface dimensions of subracks and plug-in units, Dimensions and design aspects for 1U chassis, IEC 60297-3-101, 1st edn., 2004-2008. Switching Systems: Architecture and Performances 7.1 Introduction In Chapter 6, we have described optical transmission systems-the type of equipment used in the telecommunication network to move the information bearing signal from one place to the other. Besides transmission, the other key functionality of a telecommunication network is switching, that is, the ability of sending the signal from its origin to the correct destination selecting a suitable route in the network. Differently from transmission, that essentially coincides with a physical function, switching exists almost at every network layer, since each layer needs to create routes for its proper signals. This implies that while the base technology for transmission is well established and essentially unique, there is a wide variety of switching network elements, depending on the layer where they operate and on 