D-Link DES-3326SR, User Manual

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DES-3326SR Layer 3 Fast Ethernet Switch User’s Guide
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approach. Each layer has clearly defined tasks, protocol, and
interfaces for communicating with adjacent layers, but the
exact way these tasks are accomplished is left to individual
software designers. The Open Systems Interconnect (OSI)
seven-layer model has been adopted as the reference for the
description of modern networking, including the Internet.
A diagram of the OSI model is shown below (note that this is
not a complete listing of the protocols contained within each
layer of the model):
Figure 5-8. OSI Seven Layer Network Model
Each layer is a distinct set of programs executing a distinct set
of protocols designed to accomplish some necessary tasks..
They are separated from the other layers within the same
system or network, but must communicate and interoperate.
This requires very well-defined and well-known methods for
transferring messages and data. This is accomplished through
the protocol stack.