 modules through a base set of interfaces, only to have the resulting behaviors cou- pled to the complete class definition. Disabling a power supply, for instance, may exhibit significantly different behavior than disabling a switching component (Ref. 16). With CMIP and other OSI management schemes, there are three types of relationships between managed objects: Inheritance Tree. This defines the managed object class super and subclasses, much as C++ base and derived classes are related. When a class is inherited from a superclass, it possesses all the characteristics of the superclass, with additional class specific extensions (additional attributes, behaviors, and actions). Containment Tree. This defines which managed objects are contained in other managed objects. As an example, a subnetwork can contain several managed ele- ments (ME). Naming Tree. This defines the way in which individual objects are referenced within the constraints of the management architecture. From Ref. 16. CMIP (i.e., OSI management communications) communications are very different than those found in SNMP. These communications are embedded in the OSI applica- tion environment and they rely on conventional OSI peer layers for support. They use NETWORK MANAGEMENT Operations Operations Operations system system system To other Data communication network Workstation Transmission Transmission Exchange Exchange Exchange systems systems Telecommunication network T0405910-95 NOTE - The TMN boundary represented by the dotted line may extend to and manage customer/user services and equipment. Figure 21.13 General relationship of a TMN to a telecommunication network. (From Figure 1/M.3010, Ref. 20.) connection-oriented transport where SNMP uses the datagram (connectionless). In most cases these communications are acknowledged. 21.8 TELECOMMUNICATION MANAGEMENT NETWORK (TMN) Figure 21.13 shows the general relationship between a TMN and a telecommunications network which it manages. A TMN is conceptually a separate network that interfaces a telecommu