CHAPTER 5 The OSI Model and Networking Protocols

In 1977, the International Organization for Standardization formed a subcommittee called the Open Systems Interconnection (OSI) from which a seven-layered framework was established and is still used as the model for distributed communications. The OSI model is shown in Figure 5.1.

FIGURE 5.1 The OSI model

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The OSI Model

The first two layers of the OSI model involve both hardware and software. In the five upper layers (Layers 3 to 7), the OSI model typically is implemented via software only.

Crunch Time

The OSI model is represented as a stack because data that is sent across the network has ...

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