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!

The whole site in one document for easy reference!
The TCP/IP Guide

Custom Search







Table Of Contents  The TCP/IP Guide
 9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)
      9  TCP/IP Internet Layer (OSI Network Layer) Protocols
           9  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)
                9  Internet Protocol Version 4 (IP, IPv4)
                     9  IP Addressing
                          9  IP Addressing Concepts and Issues

Previous Topic/Section
Number of IP Addresses and Multihoming
Previous Page
Pages in Current Topic/Section
1
2
Next Page
IP "Classful" (Conventional) Addressing
Next Topic/Section

IP Address Management and Assignment Methods and Authorities
(Page 2 of 2)

The Original IP Address Authority: IANA

The Internet is of course “the” big IP internetwork, and requires this coordination task to be performed for millions of organizations worldwide. The job of managing IP address assignment on the Internet was originally carried out by a single organization: the Internet Assigned Number Authority (IANA). IANA was responsible for allocating IP addresses, along with other important centralized coordination functions such as managing universal parameters used for TCP/IP protocols. In the late 1990s, a new organization called the Internet Corporation for Assigned Names and Numbers (ICANN) was created. ICANN now oversees the IP address assignment task of IANA, as well as managing other tasks such as DNS name registration.

Modern IP Address Registration and Authorities

IP addresses were originally allocated directly to organizations. The original IP addressing scheme was based on classes, and so IANA would assign addresses in Class A, Class B and Class C blocks. Today, addressing is classless, using CIDR’s hierarchical addressing scheme. IANA doesn’t assign addresses directly, but rather delegates them to regional Internet registries (RIRs). These are APNIC, ARIN, LACNIC, and RIPE NCC. Each RIR can in turn delegate blocks of addresses to lower-level registries such as national Internet registries (NIRs) and local Internet registries (LIRs).

Eventually, blocks of addresses are obtained by Internet Service Providers (ISPs) for distribution to end-user organizations. Some of the ISP’s customers are “end-user” organizations, but others are (smaller) ISPs themselves. They can in turn use or “delegate” the addresses in their blocks. This can continue for several stages in a hierarchical fashion. This arrangement helps ensure that IP addresses are assigned and used in the most efficient manner possible. See the section on CIDR for more information on how this works.

IANA, ICANN and the RIRs are responsible for more than just IP address allocation, though I have concentrated on IP addresses here for obvious reasons. For more general information on IANA, ICANN, APNIC, ARIN, LACNIC and RIPE NCC, try a can of alphabet soup… or the topic on Internet registration authorities. J

 


Previous Topic/Section
Number of IP Addresses and Multihoming
Previous Page
Pages in Current Topic/Section
1
2
Next Page
IP "Classful" (Conventional) Addressing
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.