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
Summary Comparison of TCP/IP Transport Layer Protocols (UDP and TCP)
Previous Page
Pages in Current Topic/Section
1
Next Page
Name Systems and TCP/IP Name Registration and Name Resolution
Next Topic/Section

TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)

The OSI Reference Model is used to describe the architecture of networking protocols and technologies and to show how they relate to one another. In the chapter describing the OSI model, I mentioned that its seven layers could be organized into two layer groupings: the lower layers (1 through 4) and the upper layers (5 through 7). While there are certainly other ways to divide the OSI layers, I feel this split best reflects the different roles that the layers play in a network.

The lower layers are concerned primarily with the mechanics of formatting, encoding and sending data over a network; they involve software elements but are often closely associated with networking hardware devices. In contrast, the upper layers are concerned mainly with user interaction and the implementation of software applications, protocols and services that let us actually make use of the network. These elements generally don't need to worry about details, relying on the lower layers to ensure that data gets to where it needs to go reliably.

In this chapter I describe the details of the many protocols and applications that run on the upper layers in modern networks and internetworks. The organization of this chapter is quite different than the previous one. I felt that there was benefit to explaining the technologies in each of the lower layers separately. This is possible because with a few exceptions, the dividing lines between the lower layers are fairly well-established, and this helped show how the layers differ.

The upper layers are much more difficult to separate from each other, because there are many technologies and applications that implement more than one of layers 5 through 7. Furthermore, even differentiating between these layers becomes less important near the top of the networking stack. In fact, the TCP/IP protocol suite uses an architecture that lumps all the higher layers together anyway.

For these reasons, this chapter is divided functionally and not by layer. It contains four different sections that cover distinct higher-layer protocol and application areas. The first discusses naming system, especially the TCP/IP Domain Name System. The second overviews file and resource sharing protocols, with a focus on the Network File System. The third covers network configuration and management protocols, which includes the host configuration protocols BOOTP and DHCP. The last and largest section covers end-user applications and application protocols, including general file transfer, electronic mail, Usenet, the World Wide Web, interactive protocols (such as Telnet) and administration utilities.

Quick navigation to subsections and regular topics in this section



Previous Topic/Section
Summary Comparison of TCP/IP Transport Layer Protocols (UDP and TCP)
Previous Page
Pages in Current Topic/Section
1
Next Page
Name Systems and TCP/IP Name Registration and Name Resolution
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.