ata from the network elements (NE). An ideal scenario would involve one element manager to collect data from a single network element as in EM-2 and NE-n. It can be seen that this is not the case for an actual EMS product. Almost all the EMS products available in the market support management of a set of elements as shown for element manag- ers other than EM-2 in Figure 1.1. Even when data is collected from multiple NEs, the management system is still an element manager when data collection and processing NMS server Figure 1.1 Layered view of an element management system. What Is EMS? is handled on a per NE basis and functionalities offered by the EM does not include any function that represents processed output from an aggregate of data collected from different NEs. It is seen that while enhancing an EMS product or to make the product com- petitive in the market, many EMS solution developers offer some of the NMS related functionalities that involve processing of collected data from multiple NEs to display network representation of data. This point needs to be carefully noted by the reader to avoid getting confused when handling an actual EMS product that might include some NMS features as part of the product suite. Figure 1.1 showing layered views closely resembles the TMN model with the network elements in the lowest layer, above which is the element management layer followed by network management layer. The TMN model is handled in much detail in Chapter 2. The NMS server may not be the only feed that collects data from an EMS server. The EMS architecture is handled in more detail in the next section where the various feeds from an EMS sever are depicted pictorially and explained. 1.3 EMS Architecture The element management system in Figure 1.2 is the EMS server that provides FCAPS functionality. The FCAPS is short for Fault, Configuration, Accounting, Performance, and Security. Basic FCAPS functionality at element level is offered in EMS layer. The FCAPS is also referred in conjunction with the NMS layer as a