The OSI Reference Model ” Review of the seven layers of tasks that make communications systems operate .
Types of Internetworking Devices ” The main devices on an internetwork: bridges, switches, routers, and access servers.
An Internetwork Example ” A specific internetwork topology that is used as an example throughout the book.
This chapter helps you start learning about internetworking. Understanding this complex topic is the first step toward understanding the Cisco Internetwork Operating System (IOS). The IOS provides the intelligence that Cisco products require to perform their various internetworking tasks. The IOS is an operating system with a proprietary user interface, command set, configuration syntax, and so on. The IOS is to Cisco devices as Windows 2000 is to IBM-compatible personal computers. The IOS runs on all the Cisco products discussed in this text.
We encourage you to have a firm grasp of the internetworking principles surveyed in this chapter before you attempt to understand the complexities of the Cisco IOS. Internetworking is a term used to describe the collection of protocols and devices that interoperate on data networks. This chapter gives you the basic understanding of the subject; it is not meant to give you comprehensive coverage of the subject (which could take multiple books to cover completely). If you need a more extensive introduction to internetworking, a few good texts are cited in the "References" section at the end of this chapter.
When you finish this chapter, you should be comfortable with the OSI networking model and have a basic understanding of how bridges, switches, routers, and access servers work. Chapter 2, "The Basics of Device Configuration," introduces you to the basics of configuring a Cisco device.