Using the TCP/IP protocol suite as an example, it is comprised of 4 individual layers that map directly to the 7 layers of the OSI reference model.
Every individual protocol maps to one of these layers. These protocols are constantly being updated and added to as new applications are created.
Also upper layer protocols rely on the lower layers, for instance, BGP (application) relies on TCP (transport) which relies on IP (internet) then say ethernet (link).
I hop this answers your question.
Last Wiki Answer Submitted: May 6, 2010 11:57 am by Matt Mather3,610 pts.