Welcome to the OSI Reference Model study class by CoreNetworkZ Tech Solutions. Today, I will explain the Session Layer and its functions.
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 the Transport layer. This tutorial explains the role of the Session layer in a network and its critical functions.
Where is The Session Layer?
The session layer is between the Transport and Presentation layers in the OSI reference model.
You cannot find a session layer in the TCP/IP model.
If someone asks where is the Session layer in a TCP/IP model, answer them there is no separate session layer in that model. The Application layer in the TCP/IP model handles the role of the session layer.
What Does The Session Layer Do?
One of our readers, Mohammed Salman, asked the purpose of the Session Layer. Let me explain it.
The primary 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.
The Session layer communicates with the Transport layer to set up and tear down the connection.
We will learn more about the importance and working of the Session layer by studying its functions. The functions of the Session layer are listed below.
The Functions of the Session Layer are:
Jessy George asked me to write the functions of the Session Layer in the comment section. Thanks for that question Jessy, and you can read the four functions below.
It starts and ends a session across a network.
Allows applications to share information.
Ensures that information is flowing to the right place.
Communicate to the presentation layer and Transport layer.
Another question you may hear is about the maximum number of sessions supported by the Session layer in a network. The answer is simple. A session layer is there because it handles multiple sessions at a time.
We can have multiple sessions on a network due to the Session layer.
Let me explain it with a practical example. We are seeing a movie where sound and sight both should match. It is one of the applications of the Session layer.
You have learned about the working and functions of the Session layer. We will complete this tutorial by providing the list of protocols in this layer.
List of Session layer protocols
Navneeth Gopan, in the comment section, asked for a few protocols working in this layer. Well Navneeth, here is a list of ten Session Layer protocols.
- AppleTalk Data Stream Protocol (ADSP)
- AppleTalk Session Protocol (ASP)
- Call Control Protocol for Multimedia Communication
- Internet Storage Name Service
- Network Basic Input Output (NetBIOS)
- Password Authentication Protocol (PAP)
- Point-to-Point Tunneling Protocol (PPTP)
- Remote Procedure Call Protocol (RPC)
- Short Message Peer-to-Peer (SMPP)
- Secure Shell (SSH)
Suggested Readings
- Physical layer
- Data link layer
- Network layer
- Transport layer
- Session layer
- Presentation layer
- Application layer
Reference
For those researching this topic, CoreNetworkZ Tech Solutions recommends the following references.
- https://learningnetwork.cisco.com/s/article/osi-model-reference-chart
- https://community.cisco.com/t5/network-management/the-session-layer-of-the-osi-model/td-p/429434
Author: Alex George
Alex George is the Chief Editor and founder of CoreNetworkZ Tech Solutions. He is a senior software developer with 20 years of experience.
You can contact him at alex.george@corenetworkz.com.
Hi Alex,
ReplyDeleteDoes Session Layer support any protocols? If so, which are they?
Hello Jeremy,
DeleteI have published the list of protocols.
Hello Alex,
ReplyDeleteI came from your community profile on SystoSys. I like your writing style and you are doing a wonderful job.
Thank you for your compliments David.
DeleteHi Alex George, what are the functions of the OSI Session layer?
ReplyDeleteI have explained the functions in the article.
DeleteAlex,
ReplyDeleteI am preparing for CCNA. Can you share a few protocols working in Session layer?
Hello Navneeth,
DeleteThey are mentioned in the article.
What is the purpose of this session layer in the OSI Reference Model?
ReplyDeleteHello Mohammed,
DeleteThe purpose of this layer is to create, maintain, and terminate sessions.