Breif Description of the OSI Model

The OSI model is made up of " Application, Presentation, Session, Tranport, Network, Linking and Physical layers". These are stacked one below the other starting from the application layer and then ending the stack with the physical layer as its last layer. This stack is also called the protocol stack much so because each layer is a protocol and these protocols govern the way in which the layers communicate with each other. In the most general case we have one protocol stack at the source and one at the receiver. A source or receiver can be termed as nodes in the entire layout. Only the physical layers can communicate with each other directly. All other layes have to pass information from one to the other and then pass this information through the medium and rise up in the stack on the other end.