ems to distribute the TMN functional lev- els and functional areas as they prefer. The management system model that corresponds to the TMN model in Fig. 5.14 is shown in Fig. 5.17. Managed Managed node network agent Management Management network station (MS) nonSNMP Proxy device agent nonSNMP device SNMP-agents Proxy agents Fig. 5.17 The picture that SNMP gives of the management layer LSM. MSF=MS function; WS=work station The SNMP-defined node concepts are included here in a "managed network" (corresponds to the TMN traffic system) and a "management network" (corre- sponds to the TMN management system). Other differences between the TMN and the SNMP management systems are: All mpCP and msCP of SNMP use UDP and/or TCP for connectivity. The correspondence to a TMN-QAF is not defined in SNMP. Terminology differences: The correspondence to a TMN-NEF is called "SNMP agent". 5 Management and Traffic Systems The correspondence to a TMN-MF is called "SNMP proxy agent." This agent is used to connect older devices or devices not originally intended for being IP nodes ("nonSNMP device" in the model, e.g., printers, bridges). The correspondence to a TMN-OSF is called "SNMP management station". Using AMLn Models in Management Systems We have already, when we discussed TMN, indicated the potential of an AMLn model when MOs for the resources of a traffic system are to be specified. The structures of the model (layers and logical network) can be used for classifying MOs that exist in network elements. For example, if a logical-network structure model is defined, MOs for different logical networks should be kept apart. The configuration tables that are defined for layer elements in the layer structure model are obvious candidates for MOs in NEs. Tables that belong to different layers should also be kept apart, etc. An AMLn model can, however, be used for defining high level MOs as well SO that in a network of NEs, element managers (EM) and network managers (NM), operators can operate through MOs. The basis for defining such MOs i