gregated information sent from multiple agents and performs the network level functions. The manager can: Send queries to the agent Receive response from the agent Send update and edit notifications to the agent Collect data from the agent (alarm notification, performance report, etc.) The management database (MDB) is used to store management information. The data collected from the agents by the manager is processed to generate consoli- dated network level reports on fault, configuration, performance, and other man- agement functions. These processed reports as well as raw reports from the agent can be stored in MDB. The MDB serves as an archive for historical information on the managed objects. Fundamentals of EMS, NMS and OSS/BSS Manager Agent/manager Management database Agent Agent Managed objects Unmanaged objects Figure 5.2 Three-tier organizational model. There are three relational models to be discussed under OSI organizational models. They are: Two-tier model Three-tier model MoM model The components, functions performed by the components and their relation- ship, have already been discussed for the two-tier model. The three-tier model is similar to the two-tier model except for the presence of an additional "agent/man- ager" with its own management database between the manager and the agent (see Figure 5.2). We will call this additional component the intermediate component to avoid confusion in the discussion below. The manager in the intermediate component performs the role of collecting data from the managed objects. This manager can also process the data and store infor- mation in the management data base of the intermediate component. The manager in the intermediate component acts as a manager for the agents in the managed objects. The agent in the intermediate component performs the role of sending infor- mation to the top level manager above the intermediate component. It thus acts as an agent for the top level manager. The concept would be clear if you view the intermediate component as an ele- m