alues contained within the SET command. managed. CREATE, which adds a new instance of a managed object, and 3. Handles management requests from the manager to the man- can be used, for example, to create a new 'connection' in a aged objects and responses from the objects to the manager. telecommunication network. These may be categorised as operations and notifications. The DELETE, which deletes the instance of a managed object. agent therefore performs an amplifying and filtering role. ACTION, which provides a general facility for requesting actions, against existing managed objects, for example carrying As stated earlier, the manager interacts with the remote agent out a test to determine the cause of an alarm. The service using the Common Management Information Service (CMIS) therefore contains a specific action identifier. which is transmitted by the Common Management Information Protocol (CMIP). The manager can request management informa- Each of the above single requests (except for CREATE) in CMIS tion from the agent manager (solicited responses), for example by can themselves trigger off a large number of subsidiary actions, by the use of the following services provided by CMIS: the agent, on managed objects selected by scoping and filtering. MANAGER DOMAIN AGENT AGENT OBJECTS MANAGER DOMAIN 2 AGENT AGENT OBJECTS MANAGER DOMAIN 1 AGENT OBJECTS Figure 16.14 Manager and Agent within management domains Operations requests may refer to more than one managed object. illustrated in Figure 16.12. For example the managed resources may The agent performs the necessary scoping and filtering as specified be the seven layers of the OSI stack. This gives an abstract image of by the manager to select target objects, applies the operation to each the managed objects within the network, such as the routing table object, thus resulting in a (linked) response from each to the man- objects which form the layer 3 functions used by the nodes. Because ager. Facilities also exist to request the agent to either: the data relatin