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
 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 Addressing
Previous Page
Pages in Current Topic/Section
1
2
Next Page
IPv6 Address Size and Address Space
Next Topic/Section

IPv6 Addressing Overview: Addressing Model and Address Types
(Page 2 of 2)

IPv6 Address Types

One important change in the addressing model of IPv6 is the address types supported. IPv4 supported three address types: unicast, multicast and broadcast. Of these, the vast majority of actual traffic was unicast. IP multicast support was not widely deployed until many years after the Internet was established, and continues to be hampered by various issues. Use of broadcast in IP had to be severely restricted for performance reasons (we don't want any device to be able to broadcast across the entire Internet!)

IPv6 also supports three address types, but with some changes:

  • Unicast Addresses: These are standard unicast addresses as in IPv4, one per host interface.

  • Multicast Addresses: These are addresses that represent various groups of IP devices: a message sent to a multicast address goes to all devices in the group. IPv6 includes much better multicast features and many more multicast addresses than IPv4. Since multicast under IPv4 was hampered in large part due to lack of support of the feature by many hardware devices, support for multicasting is a required, not optional, part of IPv6.

  • Anycast Addresses: Anycast addressing is used when a message must be sent to any member of a group, but does not need to be sent to them all. Usually the member of the group that is easiest to reach will be sent the message. One common example of how anycast addressing could be used is in load sharing amongst a group of routers in an organization.

Key Concept: IPv6 has unicast and multicast addresses like IPv4. There is, however, no distinct concept of a broadcast address in IPv6. A new type of address, the anycast address, has been added to allow a message to be sent to any one member of a group of devices.


Implications of the Changes to Address Types in IPv6

Broadcast addressing as a distinct addressing method is gone in IPv6. Broadcast functionality is implemented using multicast addressing to groups of devices. A multicast group to which all nodes belong can be used for broadcasting in a network, for example.

An important implication of the creation of anycast addressing is removal of the strict uniqueness requirement for IP addresses. Anycast is accomplished by assigning the same IP address to more than one device. The devices must also be specifically told that they are sharing an anycast address, but the addresses themselves are structurally the same as unicast addresses.

The bulk of the remainder of this section focuses on unicast addressing, since it is by far the most important type. Multicast and anycast addressing are given special attention separately.


Previous Topic/Section
IPv6 Addressing
Previous Page
Pages in Current Topic/Section
1
2
Next Page
IPv6 Address Size and Address Space
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.