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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 Overview, Changes and Transition

Major Changes And Additions In IPv6 1 2 3 IPv6 Addressing

IPv4-IPv6 Transition: Differences of Opinion

The transition is already underway, though most people don't know about it. As I said, development of IPv6 itself is pretty much complete, though work continues on refining the protocol and also on development of IPv6-compatible versions of other protocols. The implementation of IPv6 began with the creation of development networks to test IPv6's operation. These were connected together to form an experimental IPv6 internetwork called the 6BONE (which is a contraction of the phrase “IPv6 backbone”.) This internetwork has been in operation for several years.

Experimental networks are well and good, but of course the big issue is transitioning the “real” Internet to IPv6—and here, opinion diverges rather quickly. In one camp are the corporations, organizations and individuals who are quite eager to transition to IPv6 quickly, to gain the many benefits it promises in the areas of addressing, routing and security. Others are taking a much more cautious approach, noting that the dire predictions in the mid-1990s of IPv4's imminent doom have not come to pass, and arguing that we should take our time to make sure IPv6 is going to work on a large scale.

These two groups will continue to play tug-of-war for the next few years, but it seems that the tide is now turning towards those who want to speed up the now-years-long transition. The move towards adoption of IPv6 as a production protocol is being spearheaded by a number of groups and organizations. IPv6 has a lot of support in areas outside the United States, many of which are running short of IPv4 addresses due to small allocations relative to their size. One such area is Asia, a region with billions of people, rapidly-growing Internet use and a shortage of IPv4 addresses.

Within the United States, which has the lion's share of IPv4 addresses (due to the Internet having been developed in the U.S.A.), there seems to be a bit less enthusiasm for rapid IPv6 deployment. Even here, however, IPv6 got a major “shot in the arm” in July 2003 when the United States Department of Defense (DoD) announced that starting in October of that year, it would only purchase networking products that included compatibility with IPv6. The DoD—which of course was responsible for the development of the Internet in the first place—hopes to be fully transitioned to IPv6 by 2008. This will likely have a big impact on the plans of other governmental and private organizations in the United States.

Of course, the creators of IPv6 knew from the start that transition was going to be an important issue with the new protocol. IPv6 is not compatible with IPv4 because the addressing system and datagram format are different. Yet the IPv6 designers knew that since the transition would take many years, it was necessary that they provide a way for IPv4 and IPv6 hosts to interoperate. Consider that in any transition there are always “stragglers”. Like the old Windows 3.11 PC in the corner that you still need to use once in a while, even when most of the Internet is IPv6 there will still likely be some devices that are still on IPv4 because they were never upgraded.

Major Changes And Additions In IPv6 1 2 3 IPv6 Addressing