with the relative layer protocols travel on the service channel that is a sort of header of the WDM comb. 3.2.8 Telecommunication Management Network Up to now we have described different possible design of the network that generates sets of data plane plus control plane located at various levels of the reference open systems interconnection (OSI) system. Now we want to describe the management plane, starting from the standard prescribed by ITU-T and that is potentially applicable at any type of communication network: the telecommunication management network (TMN) [51-53]. The most effective and complete implementation of this standard has been realized for the TMN controlling SDH/SONET networks and the same criteria was translated in the management of the OTN. In such networks, a small number of operations, like fault protection, are automatically carried out by the network control plane via autonomous protocols, whereas almost all the management and maintenance operations are carried out by the TMN. Networks Fundamentals and Present Architectures Layers Interfaces Business management Service management Network management Element management Embedded software FIGURE 3.45 layer Layered architecture of the TMN. In synthesis, network management software functionalities can be described with the acronyms FCAPS [52], which means Failure management Configuration management Accounting management Performance management Security management The TMN is a very complex software, and in order to describe its functions and services [54] and to provide a design direction, the layered model was used to describe it. The five layers of the TMN are represented in Figure 3.45. 3.2.8.1 Embedded Software Layer This layer aggregates all the management software that is resident in the network ele- ments: that is, the firmware that is present in the cards and the agent that runs in the net- work element control card. The firmware is the part of software generally implemented on a customized hardware that directly operates on the hardware o