Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Enjoy The TCP/IP Guide? Get the complete PDF!
The TCP/IP Guide

Custom Search






Table Of Contents  The TCP/IP Guide

Previous Topic/Section
Bit Masking (Setting, Clearing and Inverting) Using Boolean Logical Functions
Previous Page
Pages in Current Topic/Section
1
Next Page
History of the OSI Reference Model
Next Topic/Section

The Open System Interconnection (OSI) Reference Model

Models are useful because they help us understand difficult concepts and complicated systems. When it comes to networking, there are several models that are used to explain the roles played by various technologies, and how they interact. Of these, the most popular and commonly used is the Open Systems Interconnection (OSI) Reference Model.

The idea behind the OSI Reference Model is to provide a framework for both designing networking systems and for explaining how they work. As you read about networking, you will frequently find references to the various levels, or layers, of the OSI Reference Model. The existence of the model makes it easier for networks to be analyzed, designed, built and rearranged, by allowing them to be considered as modular pieces that interact in predictable ways, rather than enormous, complex monoliths.

In fact, it's pretty much impossible to read a lot about networking without encountering discussions that presume at least some knowledge of how the OSI Reference Model works. This is why I strongly advise that if you are new to the OSI Reference Model, you read this chapter carefully. While it is all arguably “background material”, reading it will help form an important foundation in your understanding of networks, and will make the rest of the Guide make more sense at the same time.

If you are quite familiar with the OSI Reference Model, you may wish to skip this chapter of the Guide, or just skim through it. You can always return later to brush up on particular issues, as needed. There are also many links that come back to the descriptions of the individual layers from various parts of the Guide.

In the pages that follow, I describe the OSI Reference Model in detail. I begin with a history of the model, and a discussion of some general concepts related to the OSI model and networking models overall. I provide a useful analogy to help you understand how the reference model works to explain the interaction of networks on multiple levels. I then describe each of the seven layers of the OSI Reference Model, and conclude with a summary of the layers and their respective functions.

Note: This section describing the OSI Reference Model is geared to a discussion of networks and internetworks in general, and not specifically to the TCP/IP protocol suite. Therefore, not all of the material in this section is directly relevant to learning about TCP/IP, though much of it is. You may also wish to refer to the topic covering the reference model that describes TCP/IP, which also discusses how the TCP/IP and OSI models compare.


Quick navigation to subsections and regular topics in this section



Previous Topic/Section
Bit Masking (Setting, Clearing and Inverting) Using Boolean Logical Functions
Previous Page
Pages in Current Topic/Section
1
Next Page
History of the OSI Reference Model
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.