tals [56,57] and SOI technology [58]. It is not possible to review, here, all the proposals and the interested reader is encouraged to access the huge technical literature on this subject. 10.4.1.2 Switches: Two Examples of All-Optical Switch Fabric Switches for packet switching are not the same as those used in circuit switching; thus, many solutions we have reviewed talking about OXCs are not usable here. The first specific requirement is the switching speed, which has to be on the order of one nanosecond or less to be suited for the application. The other requirement is a low dynamic power consumption, which is sometimes dif- ferent from the static power consumption. As a matter of fact, in the first case, the switch is assumed to operate rarely and the power is used to maintain the switch in its state, while in the dynamic case, it switches continuously. The consequence is that as anticipated, when talking about memories, MEMs and LCOS switches are not usable. Using SOAs small switches with a response time on the order of 1 ns can be realized and even faster switches can be realized using nonlinear Kerr effect in optical fibers [59,60]. None of these solutions, however, is suitable for the implementation of large switches using the traditional architectures based on space division, both from the point of view of power consumption, and frequently, of the real estate. It is sufficient to realize that an SOA with suitable characteristics to be used as a switch cross-point in a dynamical switch consumes 1 W; thus, a 128 X 128 Clos matrix based on SOAs would consume about 9kW, completely out of the target of an optical packet switch. For these reasons, several switch fabric architectures have been studied that do not need large space switches and are suitable for implementation with small and very fast switches like those that can be built with SOAs. An example of the architecture of an all-optical packet switch is the KEOPS switch, designed within the KEOPS ACTS project [61]. A functional scheme of the KEOPS swit