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  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 6 (IPv6) / IP Next Generation (IPng)
                     9  IPv6 Addressing

Previous Topic/Section
IPv6 Address and Address Notation and Prefix Representation
Previous Page
Pages in Current Topic/Section
12
3
Next Page
IPv6 Global Unicast Address Format
Next Topic/Section

IPv6 Address Space Allocation
(Page 3 of 3)

Looking at the IPv6 Address Space Plan As “Eight Eighths”

An easier way to make sense of this table is to consider the division of the IPv6 address space into eighths. Of these eight groups, one (001) has been reserved for unicast addresses; a second (000) has been used to carve out smaller reserved blocks, and a third (111) has been used for sub-blocks for local and multicast addresses. Five are completely unassigned.

You can see that the IPv6 designers have taken great care to allocate only the portion of these “eighths” of the address space they felt was needed for each type of address. For example, only a small portion of the part of the address space beginning “111” was used, with most of it left aside. In total, only 71/512ths of the address space is assigned right now, or about 14%. The other 86% is unassigned and kept aside for future use. (Bear in mind that even 1/1024th of the IPv6 address space is gargantuan—it represents trillions of trillions of addresses.)

Subsequent topics in this section provide more information on several of these address blocks. Note that the “0000 0000” reserved block is used for several special address types, including the loopback address, the “unspecified” address and IPv4 address embedding. The “1111 1111” format prefix identifies multicast addresses; this string is “FF” in hexadecimal, so any address beginning with “FF” is a multicast address in IPv6.


Previous Topic/Section
IPv6 Address and Address Notation and Prefix Representation
Previous Page
Pages in Current Topic/Section
12
3
Next Page
IPv6 Global Unicast Address Format
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.