Lecture-3 ISO Model, Network Security, and Protocols

The real benefit of the osi model is found in its

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Unformatted text preview: SI model is found in its expression of how networking actually functions. Network communications occur over a physical connection. This is true even if wireless networking devices are employed. Physical devices establish channels through which electronic signals can pass from one computer to another. Physical device channels are only one type of the seven logical channel types defined by the OSI model. Each layer of the OSI model communicates via a logical channel with its peer layer on another computer. This enables protocols based on the OSI model to support a type of authentication by being able to identify the remote communication entity as well as authenticate the source of the received data. Lecture-3 5 Encapsulation/De-encapsulation OSI layers add a head and trail to encapsulate the message. Encapsulation occurs as the data moves down through the OSI model layers from Application to Physical. The inverse action occurring as data moves up through the OSI model layers from the Physical to Application is known as de-encapsulation. Lecture-3 6 Encapsulation/De-encapsulation Process The Application layer creates a message. 2. The Application layer passes the message to the Presentation layer. 3. The Presentation layer encapsulates the message by adding information to it. Information is added at the beginning of the message (called a header) and at the end of the message (called a footer). Lecture-3 7 1. Encapsulation/Deencapsulation Process … cont. Lecture-3 8 Encapsulation/De-encapsulation Process … cont. At the Physical layer, the message is converted into electrical impulses that represent bits and is transmitted over the physical connection. 6. The receiving computer captures the bits from the physical connection and re-creates the message in the Physical layer. 7. The Physical layer strips off its information and sends the message 9 Lecture-3 5. Encapsulation/De-encapsulation Process … cont. The Data Link layer strips its information off and sends the message up to the Network layer. 9. This process of de-encapsulation is perform...
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This note was uploaded on 01/21/2014 for the course IT 205 taught by Professor Kurts during the Winter '08 term at University of Phoenix.

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