agement sys- tem (they may, however, deliver data for statistics and other information to the management system over AFs). AMFs use special connectivity service points (CSPM) in the traffic system for communication between AMFs. Interfaces between nodes of the traffic system and the management system are control points called mpCP. These are defined within the management layer and normally standardized protocols. SNMP defines the mpCP in the Internet man- agement system, while the OSI RM solution to mpCP is called CMIS/CMIP (part of TMN). OSF is the part of the management layer that exists in the management system. This part is normally a network of its own where different management func- tions are allocated to different kinds of management network nodes. Interfaces between such nodes are also control points, called msCP in AMLn. Interwork- ing management systems (not in Fig. 1.32) are also interfaced over special msCPs. An AMLn model, e.g. the logical-network structure model of a traffic system, may be used to create network managed objects (NW-MO), accessible by net- work operators for configuration activities. The boundary between the two planes becomes more visible if we collapse the N dimension for both systems (see Fig. 1.33). users AMFs and management T protocol layer Operators MAF protocol mpCP protocols Connectivity services used within manage- msCP protocols ment plane only: - OSI transport service - IIOP service - TCP/UDP service Fig. 1.33 A management plane defines all functions needed for a particular traffic system 1 Introduction to Network System Modeling This model is used for defining which functions and MOs must be specified for managing a particular traffic system. This is especially valuable since a manage- ment system may be used to manage several traffic systems in parallel. A management layer is a single control layer. We can therefore model its LSM separately from its LPMs, as for any other control layer. Figure 1.34 shows the LSM that is described for the Internet management layer (i.e.,