Internet policymakers are expected to announce next week the predicament that they've been warning about for years: The pool of available IPv4 addresses is all dried up.
Once all of the IPv4 addresses have been distributed, carriers will only be able to acquire addresses that support the replacement technology, known as IPv6, which is not backward-compatible with IPv4, the current version of the Internet's main communications protocol.
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The Internet Assigned Numbers Authority (IANA) and the Number Resource Organization (NRO) are believed to be preparing an announcement for Thursday that they have handed out all of the remaining IPv4 addresses to the Regional Internet Registries (RIRs).
The registries, in turn, will dole out the final blocks of IPv4 addresses to carriers during the next few months. Each registry -- including the American Registry for Internet Numbers (ARIN) in North America -- will be given a block of 16.7 million IPv4 addresses that they will hand out on a first-come, first-serve basis to carriers that demonstrate a need for it.
Within a few months, the five regional registries are expected to run out of their allotments of IPv4 addresses. Industry observers expect the Asia Pacific Network Information Centre (APNIC) to run out first, and AfriNIC, the Registry for Internet Number Resources for Africa, to run out last.
"The depletion of the IANA pool is an important milestone," says Fred Baker, a Cisco Fellow who chairs the Internet Engineering Task Force's IPv6 Operations Working Group. "It's not the end of the line for IPv4 as a business, as the RIRs and their members have a supply to work through for a number of months to come, and the IPv4 Internet will continue to run for years to come. But it is clearly the beginning of the end" for IPv4.
Network operators that don't move aggressively to support IPv6 on their public-facing Web sites and services will be forced to use complex, expensive translation mechanisms between IPv4 and IPv6 such as carrier-grade network address translation.
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Network operators "will make do with translation options while they have to, but the smart money is on IPv6," Baker adds. "Comcast, Google, Facebook and YouTube have each made a statement that CIOs need to heed. The future of their businesses on the Internet depends on native IPv6 deployment.''
John Curran, president and CEO of ARIN, has been warning U.S. companies, government agencies and other organizations to have their public-facing Web sites ready to support native IPv6 traffic by the end of 2011. Curran says the pressure will be on network operators once the regional registries run out of IPv4 address space.
"It won't be long before organizations that require larger contiguous blocks of address space will only be able to receive them in IPv6," Curran says. "Contiguous blocks of IP address space are necessary for activities like building out new large networks and adding new customers to existing networks without causing additional burden on the Internet routing infrastructure."
Created 30 years ago, IPv4 has a 32-bit addressing scheme and can support approximately 4.3 billion devices connected directly to the Internet.
The Internet engineering community has warned network operators for a decade that the day would come when IPv4 addresses would run out. They prepared an upgrade called IPv6 that features a 128-bit addressing scheme and can support vastly more devices -- 2 to the 128th power. IPv6 also includes built-in security with IPsec and easier management through autoconfiguration of devices.
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"IPv6 is ready, and it has been ready for a long time," says IETF Chairman Russ Housley, an Internet security consultant. "This milestone simply increases the urgency for IPv6 deployment. The explosive growth of the Internet can only continue with the bigger address space offered by IPv6."
Despite the benefits -- and apparent inevitability -- of IPv6, few network operators have deployed it. As of October 2010, Arbor Networks reported that IPv6 represented less than 1/20 of 1% of overall Internet traffic. The remaining 99.95% of Internet traffic uses IPv4.
IANA depletion "is a wake-up event," says Martin Levy, director of IPv6 strategy at Hurricane Electric, which claims to have the largest, most interconnected IPv6 backbone network in the world. "Network managers need to be aware of this, and they need to know in no uncertain terms that they will be able to survive with the amount of IPv4 addresses they have today and that they have a viable IPv6 plan because they need to talk to the rest of the world."
Levy says that organizations without IPv6 deployment plans are behind schedule and putting their ability to grow their Internet-based businesses at risk.
"At some point, you're going to have an event that will cause your entity not to get IPv4 address space, or some partner, supplier or customer will not be able to get IPv4 address space, and you will at that point realize that you need to be ready for IPv6 on that day," Levy says. "It won't be a cheap upgrade if you wait until that day."
Housley says network operators shouldn't panic when IPv4 addresses are depleted at either the IANA level next week or at the registry level in a few months. The Internet will continue to operate as before, with little short-term impact, he says.
"There is no crisis, but there is a need for action so that the Internet can continue to grow," Housley says. "The transition to IPv6 requires the attention of vendors, ISPs, CEOs, system and network administrators, content providers and many others. However, our parents, spouses and children will be largely unaware of the transition. They will continue to be amazed of the endless possibilities offered by the growing Internet."