Internet Protocols - D-Link DES-3326SR Manual

D-Link DES-3326SR Layer 3 Switch

Internet Protocols

This is a brief introduction to the suite of Internet Protocols frequently referred to as TCP/IP. It is intended to give the reader
a reasonable understanding of the available facilities and some familiarity with terminology. It is not intended to be a
complete description.
Protocol Layering
The Internet Protocol (IP) divides the tasks necessary to route and forward packets across networks by using a layered
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 B- 1. 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.
Protocol layering as simply a tool for visualizing the organization of the necessary software and hardware in a network. In
this view, Layer 2 represents Switching and Layer 3 represents routing. Protocol layering is actually a set of guidelines used
in writing programs and designing hardware that delegate network functions and allow the layers to communicate. How
these layers communicate within a stack (for example, within a given computer) is left to the operating system programmers.
192