It has seven layers
7.application
provides services directly to user applications.because of the potentially wide variety of applications,this layer must provide a wealth of services.Among these services are establishing privacy mechanisms,authenticating the intended communication partners and determining if adequate resources are present.
6.presentation
presents data transformations to provide a common interface for user applications, including services such as reformatting,data compression and encryption.
5.session
establishes,manages and ends user connection and manages interaction between end systems.service include such things as establishing communications as full or half duplex and grouping data.
4.transport
insulates the three upper layers. 5 through 7,from having to deal with the complexities of layers 1 through 3 by providing the functions necessary to guarantee a reliable network link.among other functions,this layer provides error recovery and flow control between the two end points of the network connection.
provides services directly to user applications.because of the potentially wide variety of applications,this layer must provide a wealth of services.Among these services are establishing privacy mechanisms,authenticating the intended communication partners and determining if adequate resources are present.
6.presentation
presents data transformations to provide a common interface for user applications, including services such as reformatting,data compression and encryption.
5.session
establishes,manages and ends user connection and manages interaction between end systems.service include such things as establishing communications as full or half duplex and grouping data.
4.transport
insulates the three upper layers. 5 through 7,from having to deal with the complexities of layers 1 through 3 by providing the functions necessary to guarantee a reliable network link.among other functions,this layer provides error recovery and flow control between the two end points of the network connection.
3.Network
Establishes,maintains and terminate network connections. among other functions,standards define how data routing and relaying are handled.
2.Data link
Ensures the reliability of the physical link established at layer 1.standards define how data frames are recognised and provide necessary flow control and error handling at the frame level.
1.physical layer
controls transmission of the raw bit stream over the transmission medium.standards for this layer define such parameters as the amount of signal voltage swing the duration of voltages (bits) and so on.
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