in guaranteeing, among the other things, that the SLAs with other customers are not violated, that the billing is done in the correct way and that all is reported to the central management place. After a certain time also, the new connections become useless, at that point the switch of the private network uses the O-UNI-compatible protocol to delete the connection, an operation that forces the network to a connection tear down. Convergent Network Management and Control Plane A second interface completely included into the data plane is the E-NNI interface, that is, the interface that is defined to connect different administrative domains. Due to its definition, the E-NNI can connect areas of the network that are managed by different carriers, but also areas that implement different ASON-compatible protocol suites. Due to the fact that internal data relative to an administrative domain have to be hidden to entities belonging to a different administrative domains; also the E-NNI interface has the role to allow a limited number of interactions between the different administrative domains and to avoid that one of them makes undue influences on the working of the other. All the functionalities carried out by the O-UNI are also carried out by the E-NNI; addition, the E-NNI has to manage cross-domain survivability. An example is given in Figure 8.6, where end-to-end dedicated optical channel protec- tion is carried out to protect an optical layer connection between two OXC's belonging to different administrative domains. The working path (the dotted line in the figure) is used in the normal network status to convey low-priority traffic. Let us image that a failure happens on the working path (the continuous line path) between nodes (D, A) and (E, A). The connection originator node (A, A) performs low- priority traffic switch-off and commutes the traffic to be protected on the working path. However, this operation has to be advertised also to the nodes of the domain B to drive resources reservation in the transit nodes a