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LearnIT: IPv6

Learn all you need to know about IPv6 with this quick, no click learning guide.





care of address



foreign network



Hierarchical MIPv6 (HMIPv6)


home address


home agent


Internet Engineering Task Force (IETF)



Internet Protocol (IP)



IP addresses












Mobile IPv6




mobile nodes






























Printable Words-to-Go



Learn IT in ten easy steps

Directions: Read steps 1-10 and their related links. Use the glossary to look up any terms you do not know.

1. What do I need to know about IPv6?
IPv6 (Internet Protocol Version 6) is the latest level of the Internet Protocol (IP) and is now included as part of IP support in many products including the major computer operating systems. IPv6 has also been called "IPng" (IP Next Generation). Formally, IPv6 is a set of specifications from the Internet Engineering Task Force (IETF). IPv6 was designed as an evolutionary set of improvements to the current IP Version 4. Network hosts and intermediate nodes with either IPv4 or IPv6 can handle packets formatted for either level of the Internet Protocol. Users and service providers can update to IPv6 independently without having to coordinate with each other.


2. What are some of the benefits of IPv6 over IPv4?
The most obvious improvement in IPv6 over the IPv4 is that IP addresses are lengthened from 32 bits to 128 bits. This extension anticipates considerable future growth of the Internet and provides relief for what was perceived as an impending shortage of network addresses.  Extending the address space from 32 bits to 128 bits was one of the driving reasons to develop IPv6. The IPv6 addressing architecture is defined in RFC 2373, which supersedes RFC 1884.

IPv6 describes rules for three types of addressing: unicast (one host to one other host), anycast (one host to the nearest of multiple hosts), and multicast (one host to multiple hosts).
Additional advantages of IPv6 are:

  • Options are specified in an extension to the header that is examined only at the destination, thus speeding up overall network performance. 
  • The introduction of an "anycast" address provides the possibility of sending a message to the nearest of several possible gateway hosts with the idea that any one of them can manage the forwarding of the packet to others. Anycast messages can be used to update routing tables along the line.
  • Packets can be identified as belonging to a particular "flow" so that packets that are part of a multimedia presentation that needs to arrive in "real time" can be provided a higher quality-of-service relative to other customers.
  • The IPv6 header now includes extensions that allow a packet to specify a mechanism for authenticating its origin, for ensuring data integrity, and for ensuring privacy.

3. Can you describe the main changes between protocols?
In addition to the bigger addresses, IPv6 will also be easier to administer. One of the things that is going to help with that are the plug and play capabilities of IPv6, which include address auto-configuration. Address auto configuration means that hosts on the network, not routers, can generate their own address information using locally generated identifiers and prefix information supplied by routers. This means that there is actually no need to assign an IP address to each host any longer or even have a server like DHCP that does that, this will happen automatically. Other types of auto configuration capabilities include the ability to automatically discover servers such as a DNS server, and the ability to automatically delegate assigned routing prefixes to a home network or a small office.

  • Extended address space: The most obvious change is the newly extended address space, which was the driving reason to develop IPv6 in the first place.   The new address has 128 bits, which gives us space that can be used to create the hierarchical addressing system and provide plenty of IP addresses for everyone and all devices that need an IP address in the future.
  • Expanded auto configuration mechanisms: IPv6 has auto configuration mechanisms that will make our work as network engineers a lot easier. With auto configuration you can install plug and play machines without needing to configure IP addresses. It's now also much easier to re-number the networks.
  • Simplification of the header format: It has a simplified header format, which has fixed length of 40 bytes. Options are now inserted as extension headers only if needed. Extension headers are placed after the IPv6 header.
  • Extensions for authentication and privacy (security)
  • Flow labeling capability (QoS – Quality of Service)


Related Links:

In this article, Silvia Hagen, author of IPv6 Essentials provides an overview of what's new in IPv6 .

Hagen offers advice to members.

"IPv6: Seven killer capabilities" provides a summary of the most important enhancements.



4. Should I install IPv6 now?
The first thing you need to know is whether your application supports IPv6. A page of known compatible applications may be found at: It's a surprising list that includes everything from Web servers to mail servers to the network game Quake. If you have an application that supports IPv6, then it is definitely worth deploying that extra addressing service. IPv6 doesn't add a lot more overhead to your system, but unless you want to provide v6 services or access v6 sites you might want to wait a while before adding that service to a system that is tight on resources.


You'll likely find IPv6 as an option in your current operating system (see, including:


·        Macintosh

·        Windows

·        Ten versions of Unix

·        OS/390

·        OpenVMS


IPv6 is also built in to a number of vendor's routers as well.


Related Links:

Read about "IPv6" in this official IETF document. offers FAQs, information and how to documents as well as links to other sites offering IPv6 information.



5.  What can IPv6 do for network administrators?

Network administrators are no longer going to have to administer configuration information on hosts, or set up servers to do that for them. They're going to configure the routers and then all of the end nodes of the network will be auto configured using IPv6 host auto configuration.


6. What about migrating to IPv6?

With any change to standards, the big question is just how painful the upgrade or transition will be and the good news is that the transition from IPv4 to IPv6 will be simple and flexible. The upgrade will be incremental with current IPv4 hosts and routers being upgraded to IPv6, while new hosts and routers can be installed independently. Backward compatibility is allowed for, as existing IPv4 hosts or routers that have been upgraded can continue to use their current IPv4 addresses. The start-up costs are low and minimal effort is needed to upgrade existing systems to IPv6.


When developing a migration plan, organizations should start at the edge. Devices at the edge of an organization's network should run applications that use dual protocol stacks of IPv6 and IPv4. Since many ISPs may not be able to offer IPv6 immediately, the ISP's IPv4 cloud can be used to create a tunnel at an organization's locations to run IPv6 applications. With the edge devices taken care of, its time to slowly move the migration towards the core.


There should be few migration issues although there will be the typical teething problems. The Internet is currently a big cloud of IPv4. As organizations migrate to IPv6, small clouds of IPv6 will appear, which will become bigger as the IPv4 cloud shrinks. This may result in some migration or co-existence issues. Work has been done in this area, and there are applications that allow co-existence and automatically understand when to use IPv4 and when to use IPv6. These applications implement a dual stack of IPv4 and IPv6 on the same protocol stack so that a host supporting both protocols can communicate with both IPv4 and IPv6 nodes and differentiate between IPv4 and IPv6 packets. Using a dual stack means that existing IPv4 applications will work with IPv6.


7.  What more can you tell me about the cost issues associated with migrating to IPv6?
There is actually an opportunity for cost saving since there is no need to dedicate a box to act as a DHCP server and a NAT, meaning those servers can be utilized for other tasks. There is no need to buy new hardware and software: all popular operating systems such as Solaris, Red Hat, Unix, Novell, and Windows have IPv6 stacks built-in. If an earlier version of an operating system is in use, updates should be available free, with the same going for device manufacturers. Early routers and switches can be easily IPv6-enabled with a software update.

8. How would you characterize the degree of difficulty in upgrading an IPv4 network to IPv6?
For a network administrator I think ultimately it will be trivial. It will be through natural replacement of their hardware over the next couple of years, or hardware they may already have, because vendors have been shipping hardware that is capable of running IPv6. It will also be through software upgrades, they're going to get software on those devices that run IPv6.


9. When will IPv6 start filtering down to the organization? Any guesses?
Some experts predict that by the year 2005 approximately 50 % of the ISP's will offer commercial IPv6 services. In June 2003 the U.S. Department of Defense (DoD) announced to migrate its network to IPv6 by 2008, and starting October 2003 they will only buy hard- and software that supports IPv6. This will drastically accelerate the market. For organizations it is very important that they start to consider IPv6 in their investments. All organizations should do what the DoD has done, and put IPv6 support down as a requirement when buying hard- or software. This way an easy transition will be possible and hard- and software can be updated as part of the regular maintenance scenarios and life cycles. For home users it largely depends on readiness of their ISPs. In Europe many ISP's are ready but haven't announce it publicly yet. Another market that could take off quickly is the gaming and mobile device market.


Related Links: has several white papers to provide you with more in-depth information on transition strategies.

IPv6 Essentials provides a succinct, in-depth tour of all the new features and functions in IPv6, guiding you through everything you need to know to get started -- including how to configure IPv6 on hosts and routers and which applications currently support IPv6. Aimed at system and network administrators, engineers, network designers, and IT managers, this book will help you plan for, design, and integrate IPv6 into your current IPv4 infrastructure.


10. Can IPv6 help as our networks become more mobile and wireless?
Mobile IPv6 will allow a mobile node to transparently maintain connections while moving from one subnet to another. Each device is identified by its home address although it may be connecting through another network. When connecting through a foreign network, a mobile device sends its location information to a home agent, which intercepts packets intended for the device and tunnels them to the current location.  Both the routing header and the destination options headers are used with mobile IPv6 to ensure applications don't lose their TCP connection while a user is roaming from one network to another. Mobile IP uses home agent, home address, and care-of address.


IPv6 Words-to-Go Glossary:

Browse IPv6 vocabulary in this handy printable glossary.




This was last published in August 2005

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