OSI Model

What is OSI model?

⇒OSI(Open System Interconnection) model introduced in 1976 & It is developed by ISO.

→It is referenced model how applications communicate over a network.

→Because of a referenced model, it depends upon us we use or not?

➤In the OSI model if we sender than application layer is the 1st layer. 

➤And if we receiver than the physical layer is the 1st layer.

➽In OSI model

    ⇒Hardware layers→Network layer

                                      →Data link layer

                                      →Physical layer

    ⇒Software layers →Application layer

                                     →Presentation layer

                                     →Session layer

➤1st layer(Application layer)

    ↪Application layer is a user.

    ↪Application layer provides a platform to send or receive data over a network.

    ↪For example google chrome, Mozilla Firefox, internet explorer.

➤2nd layer(Presentation layer)

    ↪Presentation layer Prepares the data.

    ↪It takes data from the application layer and makes formatting code such as .doc, .mp3, .jpg, .txt etc.

    ↪This file extension makes it easy to realize that data file is formatted with a particular type of application. 

    ↪Encryption & Decryption of data is performed in the presentation layer.

➤3rd layer(session layer)

    ↪Session layer is an End to End layer.

    ↪ End to End layer means Data transfer is successful or unsuccessful.

    ↪This layer provides service to the presentation layer.

    ↪It manages to terminate a session between two communicating nodes.

➤4th layer(Transport Layer)

    ↪It is a most important layer.

    ↪ Transport layer works on data segmentation. 

    ↪Connection management, Flow control, reliable data delivery, and segmentation functions are provided in this layer.

    ↪It maintains a connection between two devices.

➤5th layer(Network layer)

    ↪Path determination & Logical addressing is performed in the network layer.

    ↪Network layer providing IP address known as a logical address.

    ↪Connect various data link type together like as token ring, FDDI, serial, IPV4, IPV6, and ethernet etc.

➤6th layer(Data link layer)

    ↪Error detection & correction of the data is performed in a data link layer.

    ↪It is defining Media Access Control(MAC) or hardware addresses.

    ↪From the network layer receive a packet and wrap it with layer two headers that are known as a frame.

➤7th layer(Physical Layer)

    ↪In physical layer transmission of digital data bits.

    ↪It is responsible for the mechanical, electrical & timing across a link.

    ↪Physical layer deals with communication media.

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