Protocol LayeringProtocol layering is a common technique to simplify networking
designs by dividing them into functional layers, and assigning protocols
to perform each layer's task.
For example, it is common to separate the functions of data delivery and
connection management into separate layers, and therefore separate protocols.
Thus, one protocol is designed to perform data delivery, and another
protocol, layered above the first, performs connection management.
The data delivery protocol is fairly simple and knows nothing of
connection management. The connection management protocol is also
fairly simple, since it doesn't need to concern itself with data
delivery.
Protocol layering produces simple protocols, each with a few
well-defined tasks. These protocols can then be assembled into
a useful whole. Individual protocols can also be removed or replaced
as needed for particular applications.
The most important layered protocol designs are the Internet's original
DoD model, and the OSI Seven Layer Model. The modern Internet represents
a fusion of both models.
