Presentation Layer - Sixth Layer in OSI Reference Model

Presentation Layer is the sixth layer in Open Systems Interconnection (OSI) Reference Model. The presentation layer is responsible for how data is presented to the user. Presentation of various forms of information like graphics, text, audio, video etc in various forms to the user is the major duty of this layer. Data encryption is also one of the functions of the presentation layer to ensure data security. The presentation layer is working as the intermediate between the Application layer and Session layer in OSI Reference Model.



How Information is Presented in the Presentation layer

Text information is presented in either ASCII or EBCDIC form to the user. In the case of graphical information, we can see various standards to present it to the user. Some examples are JPEG, BMP, GIF etc.


Three functions of the presentation layer are:

1. Encryption and Decryption
2. Compression
3. Translation

As we can see the presentation layer is responsible for data encryption and decryption. Forms of data presentation by presentation layer are in ASCII and EBCDIC.


Sub-layers in Presentation Layer

The Presentation Layer is composed of two sub-layers. They are:

1. Common Application Service Element (CASE)
2. Specific Application Service Element (SASE)

Major protocols in presentation layer are:

1. Remote Desktop Protocol
2. ASCII
3. Network Data Representation
4. External Data Representation

1. Physical layer
   
   
2. Data link layer
   
   
3. Network layer
   
   
4. Transport layer
   
   
5. Session layer
   
   
6. Presentation layer
   
   
7. Application layer

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