Chapter 2. The OSI Reference Model

After completion of this chapter, you will be able to answer the following questions:

  • What is the purpose of a network model?

  • What are the layers of the OSI model?

  • What are the characteristics of each layer of the OSI model?

  • How does the TCP/IP stack compare to the OSI model?

  • What are the well-known TCP and/or UDP port numbers for a given collection of common applications?

Way back in 1977, the International Organization for Standardization (ISO) developed a subcommittee to focus on the interoperability of multivendor communications systems. This is fancy language for getting network “thingies” to communicate with each other, even if different companies made those network “thingies.” What sprang from this ...

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