文档介绍：Chapter 2
Network Models
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2-1 LAYERED TASKS
We use the concept of layers in our daily life. As an example, let us consider two friends municate through postal mail. The process of sending a letter to a friend would plex if there were no services available from the post office.
Sender, Receiver, and Carrier Hierarchy
Topics discussed in this section:
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Figure Tasks involved in sending a letter
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2-2 THE OSI MODEL
Established in 1947, the International anization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects munications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s.
Layered Architecture Peer-to-Peer Processes
Encapsulation
Topics discussed in this section:
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ISO is anization. OSI is the model.
Note
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Figure Seven layers of the OSI model
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2-3 LAYERS IN THE OSI MODEL
In this section we briefly describe the functions of each layer in the OSI model.
Physical Layer Data Link work Layer
Transport Layer
Session Layer
Presentation Layer
Application Layer
Topics discussed in this section:
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Figure Physical layer
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