Q&A: ARIN’s John Curran on the IPv6 Transition

IPv6 will dramatically expand the number of addresses available for web sites, as well as millions of mobile devices with Internet access. That's important, as the number of IPv4 addresses is dwindling. For the past several years, the American Registry for Internet Numbers (ARIN) has been attending trade shows and conferences to spread the word about IPv4 depletion and IPv6 adoption. We recently conducted a Q-and-A with John Curran, President and CEO of ARIN, to get an update on the IPv6 transition.

Data Center Knowledge: Less than 5% of the IPv4 address space remains left in the global free pool. We’ve seen a number of estimates as to when the Internet will “run out” of IPv4. What does the current timeline look like, and what are the factors that affect the timing of the v4 expiration?

John Curran: ARIN expects the global free pool of IPv4 addresses to run out in early 2011. The specific date will depend on address space requests from ISPs and other large network operators around the globe. It is also important to note that the global free pool, from which all five Regional Internet Registries get address space, will deplete first. Then, the RIRs' supplies will deplete as they allocate their remaining address space to network operators. Finally, the network operators' own address space will be fully depleted. IPv6 adoption will be a slow, rolling transition as IPv4 space fully depletes.

DCK: Recent data from Arbor Networks finds that although IPv6 traffic has increased, it still represents just one-twentieth of one percent of all Internet traffic as of October 2010. What does this tell us about where companies are in the transition process? Does this data concern you?

Curran: In the ARIN region (Canada, US, and parts of the Caribbean), we are seeing large content providers and ISPs make public announcements on their IPv6 capabilities. These companies include very big names like Google, Netflix, Comcast, Verizon, and many other top-tier organizations. While the Internet as a whole still has much work to do to fully prepare for IPv6, we are encouraged by the progress we've seen in the past year or so.

DCK: Interop recently returned a chunk of unneeded IPv4 address space, which will extend the life of IPv4 for about a month. Are there other blocks of currently unused IPv4 addresses that could buy additional time for the v4 expiration?

Curran: Before ARIN's existence, many organizations received large blocks of IPv4 address space that they may not have been able to justify today under ARIN's community-defined policy set. Much of this address space is still in use today, but some is not. Returning unused address space is voluntary until present policies are changed. ARIN has conducted outreach to these 'legacy' address space holders, and it is possible ARIN or one of the other RIRs will get some IPv4 address space returned.

The ARIN community has not mandated a coordinated effort to reclaim underutilized IPv4 address space, though. Considering the annual global allocation rate, a coordinated reclamation effort may only extend the lifetime of IPv4 by a few months. Overall our efforts are best spent promoting IPv6 adoption and education to prepare the Internet community as a whole.

DCK: At some point there will be no IPv4 addresses available from ARIN, but other parties will continue to possess unused IPv4 addresses, which may suddenly have value. Will there be a market for these addresses? If so, who runs it and how might it work?

Curran: ARIN has a "Transfers to Specified Recipients” policy in place that allows an organization to transfer its Internet number resources to another organization in the ARIN region, provided the recipient organization receives them under ARIN contract and can justify its need for the resources. ARIN operates a Specified Transfer Listing Service to facilitate these transactions, though organizations are not required to use the listing service to use the transfer policy. We believe that these are sufficient tools for those organizations that might need some additional time in their migration to IPv6.