You want dull? I'll give you dull!

When data is received, the opposite happens. Each layer strips off its header and/or trailer before passing the data up to the layer above. As information flows back up the stack, information received from a lower layer is interpreted as both a header/trailer and data. The process of removing headers and trailers from data is called decapsulation. This mechanism enables each layer in the transmitting computer to communicate with its corresponding layer in the receiving computer. Each layer in the transmitting computer communicates with its peer layer in the receiving computer via a process called peer-to-peer communication.

Each layer has specific responsibilities and specific rules for carrying out those responsibilities, and it knows nothing about the procedures that the other layers follow. A layer carries out its tasks and delivers the message to the next layer in the protocol stack. An address mechanism is the common element that allows data to be routed through the various layers until it reaches its destination.

Each layer also has its own independent data structures. Conceptually, a layer is unaware of the data structures used by the layers above and below it. In reality, the data structures of a layer are designed to be compatible with the structures used by the surrounding layers for the sake of more efficient data transmission. Still, each layer has its own data structures and its own terminology to describe those structures.

Had enough? Gonna cry "Uncle"???