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!

Read offline with no ads or diagram watermarks!
The TCP/IP Guide

Custom Search







Table Of Contents  The TCP/IP Guide
 9  The Open System Interconnection (OSI) Reference Model
      9  General Reference Model Issues

Previous Topic/Section
How To Use The OSI Reference Model
Previous Page
Pages in Current Topic/Section
1
Next Page
Key OSI Reference Model Concepts
Next Topic/Section

Comparing the OSI Reference Model to Network Architectures and Protocol Stacks

The OSI Reference Model is not the only model used to describe the structure of networks. There are several other models and systems that are used to describe various sets of networking technologies that work together. These are generally not theoretical models, but rather describe groupings of protocols that are actively used in actual networks. They are, therefore, more often called networking architectures and protocol suites than models.

As I mentioned in the previous topic, many technologies and protocols don't “fit” well into the specific layers used in the OSI model. Similarly, most of the protocol suites used in the “real world” don't fit the OSI model exactly. This happens, of course, because they were developed independently of the OSI model. Still, most of these architectures and suites still use layers—they are just different ones than the OSI model uses.

Since the OSI model is so often referenced, it can be very helpful in making sense of other architectures, and even comparing them. Regardless of what the individual layers and technologies are called, networking protocol suites all try to accomplish the same goals in implementing a network. Thus, even though the layers are not the same, they are often comparable.

In the case of TCP/IP, a special model called the DOD model or TCP/IP model is usually used in discussions of the suite. This model has many similarities to the OSI model, but also some important differences. In other areas in the field of networking, still other models are used, such as the IEEE 802 networking architecture model. These too are similar in some ways to the OSI model but have their own unique characteristics.

Even within the scope of some individual specific technologies, a layered structure of related protocols can be seen. There are technologies that are generally considered to implement a single level of the OSI model that actually have portions that overlap several layers; examples include Ethernet and ATM. In fact, some protocols even have subprotocols that are layered within the confines of what is considered a single layer under OSI; a good example is the TCP/IP Point-to-Point Protocol (PPP), which, despite the name, is not a single protocol but a protocol suite unto itself.

 


Previous Topic/Section
How To Use The OSI Reference Model
Previous Page
Pages in Current Topic/Section
1
Next Page
Key OSI Reference Model Concepts
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.