Take the example of the OSI reference model. Suppose there are two devices, A & B. When they are communicating with each other, the data moves from the higher layer to the lower layer and each layer adds its own information to the message it receives from the layer just above it. At layer 1 the entire package is converted to a form that can be transmitted to the receiving device B. At the receiving machine, the massage is unwrapped layer by layer with each layer receiving & removing the data meant for it. For eg. Layer 2 removes the data meant for it & passes the rest to layer 3. This is called peer to peer process.
By:- Arshad Parwez, Pre-final year, Computer Science & Engg, SLIET, Lonowal.
Peer-to-peer is a communications model in which each party has the same capabilities and either party can initiate a communication session.
Other models with which it might be contrasted include the client/server model and the master/slave model. In some cases, peer-to-peer communications is implemented by giving each communication node both server and client capabilities. In recent usage, peer-to-peer has come to describe applications in which users can use the Internet to exchange files with each other directly or through a mediating server.
Within a single machine, each layer calls upon services of the layer just below it.
Layer 3, for example, uses the services provided by layer 2 and provides services for layer 4.
Between machines, layer x on one machine communicates with layer x on another machine, by using a protocol (this is Peer-to-Peer Process).
Communication between machines is therefore a peer-to-peer process using protocols appropriate to a given layer.