The Impending Internet Address Shortage

Sometime in the next six years, the Internet will run out of space. Expediting the migration to IPv6 is the solution to the impending crisis, says ARIN.

Thomas Claburn, Editor at Large, Enterprise Mobility

May 22, 2007

4 Min Read

The coming shortage of Internet Protocol addresses prompted the American Registry for Internet Numbers (ARIN) on Monday to call for a faster migration to the new Internet Protocol, IPv6.

The current version, IPv4, allows for more than 4 billion (2^32) Internet addresses. Only 19% of the IPv4 address space remains. Somewhere around 2012-13, the last Internet address bloc will be assigned and the Internet will be full, in a manner of speaking.

"We must prepare for IPv4's depletion, and ARIN's resolution to encourage that migration to IPv6 may be the impetus for more organizations to start the planning process," said John Curran, chairman of ARIN's Board of Trustees, in a statement.

IPv6 promises some 16 billion-billion possible addresses (2^128).

IP numbers are used to route traffic around the Internet. They're not the same thing as Internet domain names, which get mapped to IP numbers through the Domain Name System (DNS) because it's much easier to remember "" than ""

"Unless action is taken now, a quiet technical crisis will occur, not unlike Y2K in its complications, but without a fixed date or high level public attention," wrote Stephen M. Ryan, a partner at McDermott Will & Emery LLP and ARIN's general counsel, and Raymond A. Plzak, CEO and president of ARIN, in a forthcoming policy paper.

Ryan and Plzak foresee potential legal problems arising as address scarcity leads to a new black market in IP numbers.

IP numbers are not, like Internet domain names, seen as property by U.S. courts as a consequence of Gary Kremen's litigation to recover the domain. In the course of that dispute, Kremen in 2001 was awarded the assets of an ISP that defendant Stephen Cohen had acquired, which included IP numbers.

Kremen then engaged in litigation with ARIN to obtain his IP numbers without signing the ARIN registration service agreement. In essence, he claimed ownership rights in the IP numbers rather than the more limited set of rights governed by ARIN's contract. The U.S. District Court in San Jose, Calif., rejected Kremen's claim last year, upholding ARIN's regulatory power over IP numbers.

But a number of companies, organizations, and individuals hold IP numbers that predate ARIN's arrival on the scene in 1997. Holders of IP address blocs awarded during the Internet's early days may be sitting on a gold mine. Because they're not bound by an ARIN contract, they're theoretically free to sell their IP numbers. They haven't done so because, among other things, there's no money in it at the moment. But if the IPv6 migration continues to lag and IP addresses become scarce, holders of legacy IP address blocs could find it profitable to sell their numbers. "The characteristics of such a market are yet to form," said Ryan and Plzak in their paper, Legal And Policy Aspects Of Internet Number Resources. "It could, for example, result in delivering 'windfall' profits to those who early on obtained legacy address blocs. Corporate assets will instantly be more valuable if they have such blocs as 'assets.' "

Karl Auerbach, former member of the board of directors of ICANN, former Cisco researcher, CTO of InterWorking Labs, and an attorney, happens to be someone who obtained a legacy IP bloc back when professor Jon Postel ran the Internet.

"I've had people who want to acquire my spaces, some for some pretty hefty amounts," Auerbach said in an e-mail, noting than the legal status of IP numbers remains muddy. "Those deals fell through due to uncertainty about whether routing ISPs would honor the deal and accept routing announcements. Without the cooperation of the ISPs, an attempt to transfer space can be futile."

Auerbach said he has loaned IP address numbers to friends on a short-term basis. "But that kind of thing is from the spirit of the Internet of the '70s and '80s but certainly not the commercialized Net of today," he explained. "But don't 'cha think that in many ways the old ways are a nice residual from a more halcyon and more cooperative era?"

As for making a legitimate market for IP address space, Auerbach supports the idea. He also agrees that IPv6 transition won't be easy.

One controversial method for dealing with the IP address shortage has been the increasing use of Network Address Translation (NAT), which effectively creates a private network within a given IP address.

"The issue of NATs has been underappreciated -- they are awful things that cause great trouble," Auerbach said. "But we've learned to live with 'em and new protocols are even being designed in anticipation of NATs. So perhaps the Net of the future might evolve as an IPv4 public mesh connecting private spaces behind NATs. For that we have enough IPv4 space for decades. That scenario runs into trouble when those private spaces try to directly interconnect. But, like Scarlett O'Hara, most of us will think about that tomorrow."

About the Author(s)

Thomas Claburn

Editor at Large, Enterprise Mobility

Thomas Claburn has been writing about business and technology since 1996, for publications such as New Architect, PC Computing, InformationWeek, Salon, Wired, and Ziff Davis Smart Business. Before that, he worked in film and television, having earned a not particularly useful master's degree in film production. He wrote the original treatment for 3DO's Killing Time, a short story that appeared in On Spec, and the screenplay for an independent film called The Hanged Man, which he would later direct. He's the author of a science fiction novel, Reflecting Fires, and a sadly neglected blog, Lot 49. His iPhone game, Blocfall, is available through the iTunes App Store. His wife is a talented jazz singer; he does not sing, which is for the best.

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