OSI model in Computer Networking
Brief introduction to OSI Model and it's layers
OSI Model stands for Open System Interconnection Model. There are Seven layers in the OSI model.
Below given an amazing representation of the Seven Layers of the OSI model
(This image is found on the Cloudflare website)
Every layer will have different applications, protocols, and devices, which we will discuss below.
Application Layer
In the Application layer, direct interaction with user data takes place. It relies on Data Manipulation and Protocols, which the software does to present meaningful data to the user. It includes HTTP, File Transfer Protocols, TELNET, SMTP, etc.
Presentation Layer
So the data we got from Application Layer will be in form of characters, Numbers. The Presentation layer will collect the data from the Application layer and will represent the data in the form of machinery readable from i.e. Binary Form. It is responsible for the translation, encryption, and compression of data. Here SSL Protocol is used for encryption and decryption.
Session Layer
Now the Data we collected in the presentation layer is sent to the Session Layer and this layer decides the opening and closing of communication or data transfer between the two devices. It ensures that the session(The time between the opening and closing of the data sharing or communication) is open till the complete transfer of data takes place. It also ensures the addition of checkpoints while transferring the data.
Transport Layer
After the Session Layer, the data is transferred to the transport layer. This layer is responsible for end-to-end communication between the two devices. This includes taking data from the session layer and breaking it up into chunks called segments before sending it to the Network Layer. The transport layer on the receiving device is responsible for reassembling the segments into data the session layer can consume. It has protocols like UDP and TCP which tell how data is transferred over a network.
Network Layer and Data Link Layer
The network layer is used to transfer data between two devices, if they are on the same network then this layer is of no use whereas the Data link layer is used to transfer data between two devices on the same network. They both are responsible for flow control and error control in intra-network communication.
Physical Layer
This layer includes the physical equipment involved in the data transfer, such as the wires, cables, etc.
For data to be presented in a human-readable format, it must go through all seven layers down to the sender and up to the first layer to the receiver.
To learn more about networking watch Kunal Kushwaha 's video on networking