 the two parts must communicate. A special protocol, the IN Application Part (INAP in Fig. 3.91), is developed to allow this. INAP is a transaction-oriented protocol used in today's public networks that use CCS for transport. For more information on the IN concept, see ITU-T recommen- dations in the 1200 series. The structure of logical networks in Fig. 3.91 also guides the structure of the Logical Network Management System. There is one subsystem for each process- controlling logical network (teleservice and connection resources are managed via their resource controllers). These subsystems are independent of each other. The Logical Network Management System comprises only such management functions that can be identified in the D- and C-dimensions (since that is the context for logi- cal networks). Management systems for physical networks must also comprise operation and maintenance functions that include the P-dimensions, i.e. identify and operate on physical nodes (consisting of hardware and software) and how they are interconnected. Management functions defined by the Logical Network Management System pri- marily handle network resources that are data, like subscriber data used by tele- service process control functions, routing data in the RA, route data in the RM, configuration data (installing new types of resource controllers, installing new con- nectivity domains) and address translation data in the AT. In addition, it handles alarms that are related to logical resources (and reported by resource controllers), charging data and traffic data for statistical analysis in the management system, e.g. for network dimensioning (adding more transport resources, changing routing tables, etc.). Management functions related to the P-dimension (not represented in Fig. 3.91) operate on single physical nodes. They handle all kinds of P-dimension-related functions, like software installation, upgrades, fault handling and recovery, as well as hardware fault detection, correction and recovery. 3 Logical Network Modelling 