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What you mean by OSI Model? Functions of each layer in the OSI model?

Updated on December 8, 2010

OSI Model and functions of each layer.



OSI model is a way of describing how different applications and protocols interact on network-aware devices.

Functions of each Layer:

Physical Layer(Layer 1):This layer defines the physical and electrical characteristics of the network. Helps to pass strings(data) of ones and zeros down the wire.

Device:Hub, NIC, Repeater.. etc

Data Link Layer:

It defines the acess strategy for sharing the physical medium. Helps convert the bits into frame.

Devices: Bridge, Switch

Network Layer:

Layer 3 is the Network Layer, providing a means for communicating open systems to establish, maintain and terminate network connections.


Transport Layer:

It provides two communicating presentation entities to exchange data with eachother.

Session Layer:

The main function of Session Layer is to ensure data reliability and integrity.

Presentation Layer:

Application data is either unpacked or packed only in this layer. Protocol conversions, encryption/decryption and graphics expansion all takes place here.

Application Layer:

This is where you find your end-user and end-application protocols, such as telnet, ftp, and mail(pop3 and smtp).




Friends you have anything to update. You can do it.



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    • profile image

      SAEED 6 years ago

      nice n simple

    • profile image

      letriskadhanniel 6 years ago

      absolutely perfect :)

    • profile image

      anika 6 years ago


    • profile image

      pawan 6 years ago

      saaalo session layer galat de rakha hai...

    • profile image

      Pankaj 7 years ago

      Very Good.

    • profile image

      birhanu abay 7 years ago

      it is short and presice

    • profile image

      Fazil 7 years ago

      Simply nice

    • profile image

      walter 7 years ago

      check transport and session layers you have interchanged their content.thanks.short and brief.

    • profile image

      walter 7 years ago

      check transport and session layers you have interchanged their content.thanks.short and brief.

    • profile image

      Sumit Singh Gehlot 7 years ago

      Written in nice way and easily understandable.

    • profile image

      Venkat_VNR 7 years ago

      Very nice but need to be defined more about the technical terms used. There is one mistake in Transport layer.

    • profile image

      Suman dhiman 7 years ago

      Thank you very much

    • profile image

      Snehasish Das 7 years ago

      sorry its not the Network Layer but the Transport Layer

    • profile image

      Snehasish Das 7 years ago

      the function of transport layer is given wrong.

      Network Layer: Mainly provides a logical connection between the source and destination.

      plz update it

    • profile image

      tahir 8 years ago

      very effective.... thanks

    • profile image

      Suniel 8 years ago

      very Easily to understand, tonnes of thanks..

    • profile image

      fahad 8 years ago

      very nice and simple