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Mohammad Imran
Mohammad Imran

Posted on • Originally published at imransaifi.hashnode.dev on

OSI Model in Computer Networking ( Structure of Network)

Hey there! I'm Imran, I am working with DevOps tools and technologies and learning them also. I believe in learning in public, sharing my learnings and knowledge with everyone in the community and learn from everyone in the community. And I am writing my first blog about a topic in Computer Networking that I learned in Computer Networking course by Kunal Kushwaha and other sources.

OSI Model

  • OSI stands for Open Systems Interconnection Model.
  • OSI consists of seven layers and each layer performs a particular network function.

Layers of OSI Model

computer-network-osi-model-layers.png

1. Application Layer

  • It is the topmost layer in OSI model.
  • It is implemented in Software.
  • This layer provides services to the user.
  • This layer includes all high level protocols like Telnet , DNS , HTTP , FTP , SMTP , etc.

2. Presentation Layer

It is responsible for :

  • Data encryption/decryption
  • Character/string conversion
  • Data compression
  • Graphic handling
  • Translation

The presentation layer mainly translates data between the application layer and the network format

3. Session Layer

It is used to :

  • Establish sessions
  • Manage sessions
  • Terminate the sessions

It controls the connections/sessions between computers. It establishes, manages, and terminates the connections/sessions between the local and remote application

4. Transport Layer

  • It is responsible for error-free and end-to-end delivery of data.
  • The protocols defined here are TCP ( Transmission Control Protocol ) and UDP ( User Datagram Protocol ).

Transport Layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers.

5. network layer

  • It is responsible for moving the data packets from source to the destination.
  • It works for the transmission of received data segments from one computer to another that is located in a different network
  • Router lives over here.
  • It assigns sender's and receiver's IP address to every segment and it forms and IP packet. This is known as logical addressing.

6. Data Link Layer

  • The data link layer is responsible for error free transfer of data frames.
  • The main function of this layer is to make sure data transfer is error-free from one node to another, over the physical layer.
  • The packet received from the Network layer is further divided into frames depending on the frame size of NIC(Network Interface Card).

7. Physical Layer

  • It is the lowest layer of the OSI model.
  • it provide physical medium through which bits are transmitted.
  • The physical layer contains information in the form of bits.
  • It is responsible for the actual physical connection between the devices.

So this is the article/blog. I hope you find it informative and helpful. If you like it please follow , like and share. I will keep writing informative blogs related to DevOps. Pleae give your feedback in the comments. Thank You !!!!

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