IPv6 Transition: The Time is (Finally) Here

Driven by an explosion in the number of connected devices, the Internet is rapidly running out of globally unique, routable IPv4 addresses. Though the industry has been talking for nearly a decade about the need to transition to IPv6, the time for enterprises to make the move might be finally at hand.

The population of Internet-connected devices is projected to grow from six billion today to 15 billion in 2015 because of increases both in the number of users and the number of Internet-connected devices per user - among them computers, TVs, smartphones, tablets, game consoles, smart appliances and smart-grid utility meters.

The free pool of addresses held by the Internet Assigned Numbers Authority (IANA) was depleted in February 2011. And the free address pools previously assigned by IANA to the various Regional Internet Registries (RIRs) are expected to be exhausted by 2013. Soon public IPv4 addresses will become at best scarce; at worst non-existent. It's time for enterprise IT organizations, ISPs and Web properties such as Yahoo! and Google to address this challenge.

Support for IPv6-Only Newcomers

There are a number of reasons enterprise networks should support IPv6, including government regulations and mandates, new IPv6 applications and enhanced security. However, for most organizations, the transition will be driven initially by the need to provide a full set of services to partners and new Internet users who are accessing the Internet with IPv6-only devices. Such Internet newcomers could become quite numerous, especially as smartphones transition to 4G technologies such as Long Term Evolution (LTE).

Enterprises can deliver Web services to IPv6-only clients by providing Network Address Translation (NAT) 64 and Address Family Translation (AFT) functions in routers, load-balancing devices or other types of reverse proxies. AFT involves the translation of an address from one IP address family to another. NAT64  refers to the bidirectional translation between an IPv6 address and an IPv4 address when the initiator is on the IPv6 side. Another translation function, NAT46, applies when the initiator is on the IPv4 side.
 
Enterprise employees will soon need access to new IPv6 content and services appearing on the Internet. If the ISP does not provide NAT46 services, it might be sufficient initially to use dual-stack application proxies for email and Web access in conjunction with IPv6 access. One way to accomplish this is that, as the ISP begins to support IPv6 routing, each existing subscriber can be issued a routable IPv6 address block in addition to his routable IPv4 address block or shared IPv4 address. The subscriber's end systems would then select the appropriate stack with which to connect to another computer on the intranet or Internet.

Intranets Can Keep Using IPv4 for Years

In general, IPv4 address exhaustion will not affect operations within the enterprise intranet; users can continue to access internal applications using IPv4 for years after the Internet transitions to IPv6. An exception might be where an enterprise uses a small block of public IPv4 addresses in its intranet and then finds that it needs a large number of additional addresses to accommodate new employees.

This problem could be solved by either a transition to IPv6 or a transition to a private IPv4 address with the use of NAT. The latter approach might not be the best choice in instances where the enterprise wants to leverage certain applications, such as Microsoft Windows 2008 Clustering, that run on IPv6 by default. On an IPv4 network, this class of application would typically tunnel the IPv6 through IPv4; tunneling, however, would reduce the ability of network management tools to monitor and control traffic.

Transition Will Happen: How to Get Started

After so many years of discussion without an actual transition to IPv6, some might think that the transition will never happen. That would be a mistake. At a minimum, IT organizations need to plan for how they will support IPv6 when the need arises. A key part of that plan is to begin acquiring only equipment that supports IPv6.

Organizations wanting to be more proactive in their IPv6 transition can start by establishing a Web presence on the IPv6 Internet by acquiring a block of routable IPv6 addresses to be used in their Internet-facing data centers. IT would need to configure IPv6 routing on the enterprise's routers and possibly on other layer 3 devices in those data centers, as well as enable IPv6 on the front end of all Web servers.