Get Explanation for OSI Model Layers in Detail

The OSI or Open System Interconnection is a conceptual network model that was developed by the ‘International Standards Organization’. This model allows a huge amount of communication devices to interacts with one another utilizing the standard protocols.

In other words, you can say that OSI gives a standard for various computer systems, with which those systems can communicate with themselves. The basic concept of the OSI model is to divide the communication system into seven layers, where one layer sits on top of another.

An individual layer of the OSI model can handle a specific job and can interact with the layer above and below it.

What is the significance of the OSI Model?

The Internet that we access now does not follow the OSI model instead it follows a model “TCP/IP”, that is easy to implement. The utilization of the OSI model is for reference purposes if there is some issue with the network. When there is some issue in the network, then with the help of the OSI layer, you can break the problem and then isolate the source of that issue. Once the network problem points to a single layer of the OSI model, then you can easily rectify that issue.

7 layers of Networking – Explanation

You will get a detailed explanation in regard to the seven layers of the OSI Model here. Those seven layers are as follows – “Physical”, “Data Link”, “Network”, “Transport”, “Session”, “Presentation” and “Application” So, follow the sub methods below.

Application Layer

The application layer is the only layer that communicates with the data provided by the user. To start an interaction the applications such as the email clients and browsers depend upon this layer. The application layer is responsible for any data manipulations and the protocol that the software relies on to give meaningful information to the user. The protocols that this layer contains are “HTTP”, “SMTP”.

Presentation Layer

The presentation layer is mainly in charge of preparing data. So , the application layer can utilize that data. In other words, you can say that this layer transforms the data into a format so that, the application layer can accept it. This layer has the responsibility for compression, encryption, and translation of the data.

Session Layer

The session layer has the responsibility to open communication between two particular devices and even close it. A session is a time spent between once the communication is opened and closed. This layer makes sure that the session remains open quite long, so as to exchange all the data and then quickly closes that session. So, there is no wastage of data. 

This layer has the capability to synchronize the transfer of data with checkpoints. If after it sends some part of data, and there is no connectivity, then a specific checkpoint is stored in this layer. Therefore, once the internet connection is back again, then the data transfer will be resumed from the last checkpoint that was stored. If no checkpoints for a specific data transfer is saved, then that whole transfer will begin from scratch.

Transport Layer

The Transport layer’s responsibility is to have an end to end communication between two devices. This means to accept data from the session layer and then break that data into chunks before they are sent to the network layer. Those chunks of data are known as segments. On the receiving device, the transport layer assembles the segments into the data, so that the session layer can accept it.

This layer is also in charge of error, flow control. The flow control ascertains the full speed of the transmission. This makes sure that a sender having a fast connection does not clog a receiver who has a slow connection. The error control on the receiving end ensures that the data received is complete.

Network Layer

The network layer facilitates the transfer of data between two networks that are different. This layer breaks the segments from the transport layer into even smaller units known as packets on the sender device. But, in the receiver device, those packets are reassembled into segments and transferred to the transport layer.

Even, this layer is responsible to look for the best physical path for the data to go its destination. This search process for the best physical path is known as routing.

Data Link Layer

The data link layer allows the transfer of data between two devices that are on the same network. This layer takes the packets from the network layer and then breaks them into even small pieces known as “frames”. This layer is responsible for the flow and error control of intra-network communication.

Physical Layer

The physical layer involves any physical equipment like switches, computers, cables and etc. This layer alters the small units of segments i.e frames into bits of binary data. Both the sender and receiver must agree on a signal convention so that the 0’s can be distinguished from 1’s.