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What is OSI Model and how they work

OSI Model :

It is developed by representatives of major computer and telecommunication companies beginning in 1983OSI Model may be defined as a standard referenced model by which we can communicate or share our data from one machine to another .Its purpose is to guide product implementors so that their products will consistently work with other products. The reference model defines seven layers of functions that take place at each end of a communication.

The Open Systems Interconnect (OSI) model has seven layers. This article describes and explains them, beginning with the Highest of layer 


Application layer.
Presentation layer 
Session layer 
Transport layer 
Network Layer
Data link Layer 
Physical Layer



Application layer :-
       This the top most layer  in osi model in this layer user directly interact with a very high level protocol like http, ftp,telnet, smtp etc.


Presentation layer :-
     It is a layer number 6 in soi model this laye is responsible for the presentation the data format like data is audio video encrypt decrypt .This layer change the format of data when receiving or sending it means decrypt or encrypt data .

Session layer :-
    It is a layer number 5 in osi model. It is responsible for create to session betweeb two or more comunication ddevices and also responsible for teardom disconnect session between communication devices.It iis also create a dialouge controller of the communication process.

4 Transport layer :-
     It is a layer number fourth in the OSI model . This layer is responsible for transfer data from source to destination with the help of two protocol .

    1 . TCP                   Transmission controll protocol
    2    UDP                  User data gram protocol



  TCP :-

  
It is connection oriented protocol that gives the acknowledge after the data transfer so it is more reliable      than UDP.

 
 UDP :- 

  
Broadcast
 It is connection less protocol that doesn't give any acknowledge after data transfer so it is not reliable protocol but this is more  fast than TCP.  
 CRC:- 

   
Cyclic redundancy check .It is used to correct the error in transfer layer.


Network Layer :-

   This is responsible for provide the logical connectivity of the communication devices in to the network with

the help of ip.






Data link layer :-
  
It is layer number two in OSI model and called error detedtion layer have two sub layer LLC  and Mac
LLC   logical link layer.
Layer 2nd is used for connect physical layer to network layer.
FCS   Fram check sequence .It is used on data link layer and used to detect the error in to data link .



1 Physical Layer :- 
    It is 1st layer of OSI model it is resposible for the physical connectivity of communication device . Hub lan card , NIC etc.
  

  





What is OSI Model and how they work Reviewed by techratn on 1:16 AM Rating: 5

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