OSI model and protocols on each layer

 OSI Model (Open System Interconnection)

It is the backbone of computer networking .

It is proposed by ISO(International standard organization) to make communication of two system no matter what thier architecture is.

All layers are interconnected and this model is logical model to trace the flow of data transfer in network.

So , All seven layers are -



1. Physical Layer

It’s main responsibility is to establish and maintain the physical transmission of data between network devices. It deals with the physical aspects of data transmission, such as the electrical, mechanical, and procedural characteristics of the physical medium.

Below are some protocol of this layer.


2. DataLink Layer

Its primary role is to provide reliable and error-free data transfer between two directly connected nodes on a network. The Data Link Layer takes packets from the Network Layer (Layer 3) and encapsulates them into frames for transmission across the physical medium.

Below are some protocol of this layer.

3. Network Layer

It is responsible for logical addressing, routing, and forwarding of data packets between different networks. Its primary function is to enable end-to-end communication across multiple network segments.

Below are some protocol of this layer.


4. Transport Layer

Its primary responsibility is to provide reliable and efficient end-to-end delivery of data between hosts or endpoints on a network. The Transport Layer ensures that data is transmitted accurately, in the correct order, and without errors or losses.

Below are some protocol of this layer.


5. Session Layer

It provides services for establishing, managing, and terminating sessions or connections between applications. Its primary role is to facilitate communication and coordination between different applications or processes running on different network devices.

Below are some protocol of this layer.


6. Presentation Layer

It is responsible for the presentation and formatting of data between network systems. Its main work is data transformation, encryption and decryption, compression and decompression, and providing a common representation of data for different systems.

Below are some protocol of this layer.


7. Application Layer

It is the top most layer of OSI model .It deals with end-user by interacting with it. This layer interacts directly with the application software and serves as a bridge between the network and the user.

It has following protocols -






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