Notes-Computer Networks

OSI (Open Systems Interconnection)

It is based on the process of communication between two end users in a telecommunication network.It can be divided into layers,with each layer adding its own set of special,related functions.Each communicating user is at a computer equipped with the 7 layers of function.The layers are in 2 groups.The upper 4 layers are used whenever a message passes from or to a user.The lower three layers(upto the network layer)are used when any message passes through the host computer.The seven layers are:
¤Application layer
¤Presentation layer
¤Session layer
¤Transport layer
¤Network layer
¤Data link layer
¤Physical layer