Whenever we talk about network or data communication, we frequently mention about the OSI Model. OSI Model is the basic structure of network communication. Though the data communication looks prity simple and straight forward to the end users, but this occures through some indepedent steps. We mention these steps as layers of the Model.
In the year 1977, the International Organization for Standardization came up with the OSI Model. the OSI is the short form of Open Systems Interconnection. The OSI Model consists of the Basic Referance Model and specific protocols.
In the OSI Model there are 7 layers, responsible for totally indepedent but corelated activity for successful data communication. The layers are Application layer, Presentation layer, Session layer, Transport layer, Network layer, Datalink layer, Physical layer. Verious text books and many otehr documentaions shows the order of the layers as mentioned above. But as a suggestion I can request to remenber the layers from the Physical layer i.e. the order will be Physical layer, Datalink layer, Network layer, Transport layer, Session layer, Presentation layer, Application layer. As we go further, you can see that the Physical layer is mentioned as Layer-1, Datalink layer as Layer-2 … and so on. Let’s have a look into the activity of the layers, how they accomplish a successful data communication.