OSI MODEL

             OSI Model in networking

 OSI is stand for Open System interconnection . Basically it is known as the reference layer or system . We can say that OSI is the written work ya policy which define how a sender send his message from one machine to other machine .  Before OSI there is no any method in which a machine communicate with different machine before this you must have a same machine to communicate with each other. After coming out TCP/IP it enable the machine to communicate with each other.

In OSI there are basically seven types of Layers

Seven Layers of OSI model are:-

If we talk about the Receiver  side then the layer are like

First Layer:-Physical layer

Second Layer:-Data Link Layer

Third Layer:-Network Layer

Fourth Layer:-Transport Layer

Fifth Layer:-Session Layer

Sixth Layer:-Presentation Layer

Seventh Layer:-Application Layer

First Three layer are known as Software layers

Last Three layer are known as Hardware layers

Transport layer is known as Heart of OSI

If we talk about the sender side then the layer are like

First Layer:-Application Layer

Second Layer:-Presentation Layer

Third Layer:-Session Layer

Fourth Layer:-Transport Layer

Fifth Layer:- Network Layer

Sixth Layer:-Data Link Layer

Seventh Layer:- Physical Layer

Working Of   Different Layer  are:-

1)Physical Layer:-

                             This is  known as the first layer of OSI model (at the receiver layer). It is responsible for the physical communication or physical equipment like Ethernet , hub etc. It provide the interface between the user and the machine . It help to provide a way in which a user can communicate. 

2) Data Link Layer:-

                                   This is known as the second layer of OSI model . It is responisble for the data error and access control. Switch and Bridge operate in Data Link Layer. It lies between Physical layer and Network layer. It header contain physical address . It travel the frames/data on a single line.

3)Network Layer:-

                                This is the third layer of OSI model this is known as the hardware layer. The network layer , Data link layer and Network Layer is known as the Hardware Layer. IP address operate in this layer. It header contain the logical address . It lies between the data link layer and Transport layer. It travel the two frames on the different line. It is responsible for the source to destination packet of the message.

4)Transport Layer:-

                                 This layer is known as the heard of the OSI model . It is lies between the session and Network Layer. TCP/IP layer are work on this layer. It is responsible for the source to destination of the data . 

5)Session Layer:-

                            This layer is the fifth layer of the OSI model . It divide the network into different segmentation . In which each segmentation have a different port to received and send the message.

It is responsible for the end to end reliable communication.

6)Presentation Layer:-

                                    This is the sixth layer of the OSI model . It encode /decode the code which help to the understand the user more easily. It lies between the Session Layer and Application Layer. 

7)Application Layer:-

                                    This is the last layer of the OSI model. In this layer DNS, HTTPS, FTP, SMTP and different types of protocol work . If we are moving to the application to the network layer then header trailer is added . 

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