Presentation and Session Layer

In this article we will discuss Presentation and Session Layer, will make brief discussion on Presentation and Session Layer, In last article we discuss about Application Layer.

The presentation layer has three primary functions:

  • Formatting, or presenting, data at the source device into a compatible form for receipt by the destination device
  • Compressing data in a way that can be decompressed by the destination device
  • Encrypting data for transmission and decrypting data upon receipt

As shown in the figure, the presentation layer formats data for the application layer, and it sets standards for file formats. Some well-known standards for video include QuickTime and Motion Picture Experts Group (MPEG).  In the seven-layer OSI model of computer networking, the presentation layer is layer 6 and serves as the data translator for the network. It is sometimes called the syntax layer.

Presentation and Session Layer

Some well-known graphic image formats that are used on networks are Graphics Interchange Format (GIF), Joint Photographic Experts Group (JPEG), and Portable Network Graphics (PNG) format. Protocol refers to a standard set of guidelines under which the network operates, while architecture determines what protocol applies. Some functions of the presentation layer include character-code translation, data conversion, data encryption and decryption, and data translation.

The Session Layer

As the name implies, functions at the session layer create and maintain dialogs between source and destination applications. In the seven-layer OSI model of computer networking, the session layer is layer 5. The session layer provides the mechanism for opening, closing and managing a session between end-user application processes, i.e., a semi-permanent dialogue.

The session layer handles the exchange of information to initiate dialogs, keep them active, and to restart sessions that are disrupted or idle for a long period of time.

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