Session layer and Its Importance in OSI Reference Model

The session layer is the fifth layer in the OSI reference model. It responds to service requests from the Presentation layer and issues service requests to Transport layer. The major function of the Session layer is to create, maintain and terminate sessions. The session layer is also responsible for finding and sending data across the correct connection. To set up and tear down connection Session layer communicate with the Transport layer. Major functions of the Session layer are listed below.

The major functions of the session layer are:

1. Starts and ends a session across a network
2. Allows applications to share information.
3. Ensures that information is flowing to the right place
4. Communicate to the presentation layer and Transport layer.

We can have multiple sessions on a network due to the Session layer.

Eg: We are seeing a movie where sound and the seen both should match. It is one of the applications of the Session layer. A list of protocols working in Session layer is listed below.

Major Session layer protocols

1. AppleTalk Data Stream Protocol (ADSP)
2. AppleTalk Session Protocol (ASP)
3. Call Control Protocol for Multimedia Communication
4. Internet Storage Name Service
5. Network Basic Input Output (NetBIOS)
6. Password Authentication Protocol (PAP)
7. Point-to-Point Tunneling Protocol (PPTP)
8. Remote Procedure Call Protocol (RPC)
9. Short Message Peer-to-Peer (SMPP)
10. Secure Shell (SSH)

Suggested Readings

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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