he performed when two systems interact over a distributed environment. On the other hand, the TCP/IP model was adopted as a standard due to more widespread application of the model in domains like the Internet. It should be noted that the TCP/ IP model was developed before the OSI model. 10.10 Conclusion The network model is required to have a good understanding of how two network elements communicate whether the elements are in the same network or in two separate networks. The OSI model is the most common model used in text book descriptions to give the reader an understanding of the functionalities in an interac- tion between elements spit into a set of layers while the TCP/IP is the most popular model for implementing protocol stacks of interaction. It can be seen that TCP/ IP is a type of OSI model where a single layer performs multiple layer functions. From a functional model perspective, both the TCP/IP model and OSI model are the same. Fundamentals of EMS, NMS and OSS/BSS Additional Reading 1. Debbra Wetteroth. OSI Reference Model for Telecommunications. New York: McGraw- Hill, 2001. 2. Uyless D. Black. OSI: A Model for Computer Communications Standards. Facsimile ed. Upper Saddle River, NJ: Prentice Hall, 1990. 3. American National Standards Institute (ANSI). ISO/IEC 10731:1994, Information Technology: Open Systems Interconnection: Basic Reference Model: Conventions for the Definition of OSI Services. ISO/IEC JTC 1, 2007. 4. Charles Kozierok. The TCP/IP Guide: A Comprehensive, Illustrated Internet Protocols Reference. San Francisco, CA: No Starch Press, 2005. Chapter 11 What Is NMS? This chapter is intended to provide the reader with a basic understanding about the Network Management System (NMS). At the end of this chapter you will have a good understanding of the components in a legacy NMS, some of the open source products that implement full or partial functionality of these components, and where the network management system fits in the telecom architecture. 11.1 Introduction The network management la