network. This NM uses OSI Q3 interfaces in its own management system, but CORBA (a Qx interface according to TMN) when interworking with the other MS. This implies that the vMOs in the translators will be specified differently. MSTMN OSI L4 NM logical node OSI L4 OSI L4 L6,L5 ACSE/ROSE CMIS/CMIP MO-vMO translator Q30SI Q30SI Qx(CORBA) MSCORBA CORBA- Fig. 5.16 Part of a TMN management logical network, showing how an NM logical node that interworks with another management system may be hosted 5.4.3 The SNMP Management System The Internet was originally based on decentralized management, trying to do auto- matically as much as possible in traffic network nodes. For example, while in the PSTN/ISDN, routing tables are normally created and managed off-line the traffic nodes, the Internet handles this through a number of different routing protocols within the nodes of the TCP/IP traffic network. However, we now see a trend towards more and more centralized management functions in IP-based networks as well, especially when IP is used in public network systems such as UMTS. It is 5.4 The Management System often noticed that today's telecom networks (basically circuit-switched) are migrat- ing towards packet-switching and other Internet characteristics. However, if we look at management principles only, it is the Internet that is migrating towards tele- com principles, not the other way around. SNMP, defined by IETF, was developed to support centralized management functions, i.e., for building management systems for IP-based networks. The basic principles applied to the structure of the SNMP management system is the same as for TMN. The terminology is similar, although not identical, since TMN and SNMP have been developed by different standardization bodies and at different points in time. The SNMP management plane is defined in considerably fewer details than the corresponding TMN model, primarily because SNMP Does not consider interworking with any other type of management system and Leaves to builders of management syst