two or more communications devices or computers in which a
connection may be thought of as a set of more or less
independent protocols, each in a different layer or level.
The lowest layer governs direct host-to-host communication
between the hardware at different hosts; the highest consists
beneath it and provides a service for the layer above. Each
protocols appropriate to its layer to communicate with the
corresponding component (its "peer") on another host. Such
layered protocols are sometimes known as peer-to-peer
protocols.
The advantages of layered
protocols is that the methods of
passing information from one layer to another are specified
clearly as part of the
protocol suite, and changes within a
protocol layer are prevented from affecting the other layers.
This greatly simplifies the task of designing and maintaining
communication systems.
Examples of layered protocols are
TCP/IP's five layer
(1997-05-05)