On Aug. 2, 2005, the department of E-Government and Information Technology of the Office of Management and Budget issued OMB Memorandum 05-22, which directed all U.S. federal government agencies to transition their network backbones to IPv6. The memorandum requires that the agencies' network backbones be ready to transmit both IPv4 and IPv6 traffic, and support IPv4 and IPv6 addresses, all by June 30, 2008.
But, transitioning to the next generation Internet has been described by some IT professionals as something akin to changing the engine on a moving airplane. The degree of difficulty in transitioning to IPv6 is enormous, particularly for large, complex organizations such as the U.S. federal government or global companies. The main hurdle associated with wide-scale deployment of IPv6 is the problem of moving from a large, installed base of IPv4 networks and applications. The requirement to upgrade current networks that will enable IPv6 represents a significant economic challenge to most organizations because of inherent legacy issues. In the case of the U.S. federal government, some have put the price tag for transitioning to IPv6 anywhere from $25 billion to $75 billion.
Staying with IPv4 for the long term, however, is not an option. In May of 2007, the American Registry for Internet Numbers (ARIN) issued an advisory to the Internet technical community suggesting that transition to IPv6 will be necessary. With only 19 percent of IPv4 address space remaining, IPv6 migration will be necessary for any application requiring ongoing availability of contiguous IP addresses.
Transitioning to IPv6 is a necessity
It's a necessity to begin transitioning to IPv6. So, what's an organization to do? Most IT experts agree that interoperability is the answer. Being able to communicate between the two protocols provides the best transition strategy. There are currently three transition mechanisms: dual stack, tunneling and translators.
Transition mechanism #1: Dual stack
One of the main transition techniques used is the dual stack method, which can be used in both the network nodes (workstations and servers) and routers. In order to work effectively, the dual stack must be implemented in all the routers in a network. There is no communication between IPv4 and IPv6; applications must be able to support both modes. The challenge with the dual stack method is that all network resources need to have enough processing power and memory to support two different IP stacks. Also, two IP stacks mean dual management support--which increases IT expenditures.
Transition mechanism #2: Tunnels
Another transitioning technique is the use of tunnels. Tunneling solutions encapsulate one protocol type within another protocol. This requires a dual stack at each end of the tunnel. The routers involved in this method must be able to map the end addresses to each other. The engineering complexity of this method makes large-scale deployment extremely difficult, and would undoubtedly require, for most organizations, the support of internal and external engineering expertise.
Transition mechanism #3: Translators
A recent development in transitioning technology is a significant promise held by translation devices. Once considered the tool of last resort by the IETF (Internet Engineering Task Force), translation schemes are becoming increasingly popular transitioning approaches. Translation technology is used when an IPv6-only host is required to communicate with an IPv4 host. Translation remains the only method of IPv6 transition that permits network nodes to completely remove IPv4 addresses.
This offers significant advantages over other transition approaches: the ability to integrate IPv6-only devices into their networks while maintaining support for IPv4-only legacy devices. Plus, it preserves end-to-end connection security and accountability. A critical aspect of translation technology is its single-stack approach, which reduces the amount of routing hardware needed (thereby minimizing the IT support resources needed to maintain the network).
The single-stack approach offers a simpler, more economic path to IPv6-only networks. As IPv6 applications emerge, IT departments can simply remove elements of the IPv4 stack and replace them with IPv6 elements.
Select the right transitioning strategy
Recently, the IETF initiated a working group to explore translation approaches, which suggests that the Internet technical community is seeing translation technology in a whole new light. It is clear that IPv6 is the answer to a ubiquitous society that desires extensions to more devices, such as phones, PDAs, televisions, toasters and coffee makers. IPv4 solutions proposed for scaling the Internet address space seem only to delay the inevitable.
Migrating to IPv6 will be difficult for larger organizations, but strategies do exist that will ease transitioning. These mechanisms are not alternative to one another, but require that you know your environment so that you can select the transitioning strategy that is appropriate to your goal. For most of us, that goal is to migrate to IPv6 inexpensively, and with few headaches.