What is the OSI model explained

OSI model (Open Systems Interconnection) :- There is also a rule model in networking in which data communication is divided into 7 layers. In this model, the work of data transmission and keeping many network devices and protocols connected.

Physical Layer (PL):-

The physical layer is the bottommost layer of the OSI model.The work of the physical layer is to send data through hardware and transmission mediums. This layer includes cables, hubs, and network interface cords (NICs). The physical layer sends data in the form of bits (0 and 1).

Primary Role of the (PL):-

• The work of the physical layer is to decide the method of sending data. Such as electrical, optical, or radio signals.
• The work of the physical layer is to decide the means of transmission, such as cable or optical fiber.
• To decide the data rate and distance of transmission.

2. Data link layer (DL):- 

The work of the data link layer is to determine the correct destination by examining the data. This layer divides the data into frames. And to detect and correct the errors of the data. Switches and bridge devices come in the data link layer.

function of (DL) :-

• The function of the data link layer is to divide the data into frames.
• The function of the data link layer is to find and correct the errors.
• The function of the data link layer is to use MAC address like hardware address.
• The function of the data link layer is to control the flow control i.e. the speed of the data.

3. Network layer (NL):- 

The function of the network layer is to send data packets to the correct destination. This layer does the work of routing and addressing. Routers and layer 3 switches come in this layer.

function of the (NL) :-

• The function of the network layer is to switch data packets.
• The function of the network layer is to do IP addressing and logical addressing.
• The network layer uses routing protocols.

4. Transport layer (TL):- 

The function of the transport layer is to check whether the data has reached from one place to another in the correct manner or not. The work of this layer is to divide the data into many alternative parts and to control flow and correct error connections.

function of (TL) :-

• The work of the transport layer is to segment the data and then reassemble it.
• The work of the transport layer is to control the flow of data and to control congestion.
• The work of the transport layer is also to find and correct errors in data through TCP.

5. Session layer (SL):- 

The work of the session layer is to create and delete communication sessions between two devices. This layer has to recover the session and synchronize the data.

function of (SL) :-

• The work of the session layer is to create and delete communication sessions.
• The work of the session layer is to recover the session and restart the session.
• The work of the session layer is to synchronize the data.

6. Presentation Layer (PL):- 

The job of the presentation layer is to encode and decode the data in a format for the application layer. This layer performs data encryption, data compression and data translation.

function of the (PL) :- 

• The job of the presentation layer is to encode and decode the data.
• The job of the presentation layer is to do data encryption and decryption.
• The job of the presentation layer is to do data compression and decompression.
• The job of the presentation layer is to do data translation.

7. Application Layer (AL):- 

The application layer is at the top layer of the OSI model. Its job is to provide the network to the end-user application. This layer consists of application protocols and user interfaces.

function of the (AL) :- 

• The job of the application layer is to provide the network to the end-user application.
• The job of the application layer is to use application protocols such as HTTP, FTP, and SMTP. The application layer works to create the user interface.

Importance of the OSI model :-

1. Coordination : The OSI model coordinates between many network devices and protocols.

2. Standardization : OSI model gives a standardized framework for network communication in which many network architectures and protocols are united.

3. Modularity : OSI model divides transmission into seven layers, which makes the work of each layer clear.

Modularity in this simplifies network design and problem solving.

4. Troubleshooting : The OSI model creates a framework in the layers that works to fix the problem. With its help, problems occurring in the network are fixed.

5. Protocol development : OSI model guides to create new protocols. Due to which the development of the protocol is favorable.

Conclusion :- 

OSI model is an important model of network communication which is divided into 7 layers, the function of each layer is different. So that the data transmission work can be secured in the right way. The OSI model is used for the design of the network and to solve the problems that arise in it. And it is also used in the development of protocols.