is a LSR, but only in Telecommunication Networks Management plane Management controller NMI-A Connection Control controller plane NMI-T plane Client Routing element FIGURE 8.1 ASON standard layered model for the Automatic Switched Network management; standard interfaces between management and control plane (NMI-A) and between management and data plane (NMI-T) are shown. Control plane connection (LSP) Connection request SDH ASON connection Grooming WDM ASON connection Multiplexing Interlayer coordination Routing Survivability FIGURE 8.2 ASON Network model: a multilayer network in which a single control plane coordinates the activity of all the layers. Convergent Network Management and Control Plane MPLS virtual topology Cable Cable WDM virtual topology Physcial topology FIGURE 8.3 Scheme of a three layer network where the deployed equipment is shown in the physical topology plot (left side) and the virtual topologies at each layer are evidenced as graphs (right side). the nodes where such a machine is needed. As a consequence of this complex network architecture, three network topologies can be proposed: a physical network topology com- posed by cable ducts and buildings, a WDM virtual network topology composed by WDM systems and OXCs, and a MPLS virtual network topology composed by LSRs with the con- nectivity that is offered to them by the underlying transport layer. The different topologies are shown as graphs in Figure 8.3. The situation of this example can generally be replayed in all multilayer network archi- tecture, identifying a specific topology (physical of virtual) at each layer of the network. Identifying the correct topology is very important since in a multilayer network managed by a single control plane, every routing element refers for its routing protocols to the topol- ogy that is specific to that layer. Under a horizontal point of view, ASON is organized in administrative domains. The administrative domain is a part of the network that has its own autonomy, for example, the network belonging to