ent and management systems in a managed network. CORBA has a drawback, though: the managed object definition is not fully compatible with TMN and IETF definitions. CORBA can be seen as a 'software bus' used by clients and servers. All CORBA objects are described in an interface specification enabling other objects to communicate with them. It is used in OSS components handling traffic measurements, charging etc. SNMP is a very simple protocol. It has a short list of commands, which basically are only read or write. It is used just for communication or data interchange between the managed objects in the management information base and the management entity (or manager). The job to translate the information set on the MIB into commands for the NEs or reports for TM, is performed by agents and manager, respectively. TM Network Structure in the Distributed Dimension Technically, TM extends all over the network like a spider, collecting charging information and information about the traffic conditions through agents and information databases. Configuration and corrective commands are sent in the reverse direction. The fundamental technical plans are a guiding tool. Updated subscriber data is sent to servers/databases. See Figure 16.4. The basic management structure based on managers, agents, managed objects and MIBs, was simultaneously adopted both by IETF and ITU-T, during the early 1990s. Understanding Changing Telecommunications - Building a Successful Telecom Business This network model might induce one to think of a flat management network, without intermediate levels. As a matter of fact, this was the initial approach in the IP world, and still endures to some extent today. As mentioned, technology convergence is leading to bigger IP-based telecommunication networks but with hierarchical network structures (such as in TMN). The move towards IP in management communication is both the result of the Internet and packet switching success and improvements in IP security. The UMTS management network in Figure 16.7 ill