S This chapter is intended to provide the reader with an understanding of FCAPS intro- duced by ITU-T (International Telecommunication Union-Telecommunication Standardization Bureau) and defined in recommendation M.3400. At the end of this chapter you will have a good understanding of FCAPS functionality and how it applies to different layers of the TMN. 3.1 Introduction Associated with each layer in the TMN model are five functional areas called FCAPS that stand for fault, configuration, accounting, performance and security. These five functional areas form the basis of all network management systems for both data and telecommunications (see Figure 3.1). The information in telecom management is classified into functional areas using FCAPS. It was introduced for telecom network management by ITU-T in recom- mendation M.3400. The ISO (International Standards Organization) made the FCAPS also suited for data networks with its OSI (open system interconnection) network management model that was based on FCAPS. Further in this chapter, each of the FCAPS functional areas are taken up and discussed in detail. All ele- ment management systems are expected to provide the FCAPS function or a subset of the same. At higher levels like business, service, and network layer, derivatives of basic FCAPS functionality can be implemented like a complex event processing engine that triggers mail on business risks when network elements carrying major traffic goes down or a service request is sent to the nearest technician or set of com- mands to the network elements to replace load or restart. Fundamentals of EMS, NMS and OSS/BSS Security Performance Accounting Configuration Fault Business management layer Service management layer Network management layer Element management layer Network element layer Figure 3.1 FCAPS and TMN. 3.2 Fault Management Fault is an error or abnormal condition/behavior in a telecom network. Fault management basically involves the detection, isolation, and correction of a fault condition. The first part invo