Appendix . Fast Facts

OSI Model in Review

Table FF.1 lists the seven layers of the OSI model and significant aspects of each layer.

Table FF.1. The OSI Model

OSI Layer

Important Functions


Provides an interface between a host’s communication software and any necessary external applications.

Evaluates what resources are necessary and available resources for communication between two devices.

Synchronizes client/server applications.

Provides error control and data integrity between applications.

Provides system-independent processes to a host.


Presents data to the application layer.

Acts as a data format translator.

Handles the structuring of data and negotiating data transfer syntax to Layer 7.

Processes involved include data encryption, ...

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