OSI Model in Computer Networking ( Structure of Network)
Published: 2022-09-18 18:24:34

---
title: OSI Model in Computer Networking ( Structure of Network)
published: true
date: 2022-09-18 17:34:47 UTC
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canonical_url: https://imransaifi.hashnode.dev/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](https://cdn.hashnode.com/res/hashnode/image/upload/v1663504128630/Sps3HxBFa.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 !!!!