"You can get two years' worth of the space you need and get it locked up based on forward-looking projections and past history of usage with an 8.3 transfer," Curran explained. "But if you come to us for a regular allocation, we will give you what you need for 90 days. Then you'll have to keep coming back every 90 days."
More 8.3 transfers are likely to occur soon if ARIN and the other regional registries agree to a proposed policy change that will allow IPv4 address transfers between regions. That would allow companies in Asia - which has run out of all but a handful of IPv4 addresses held in reserve for startups - to buy unused IPv4 address space from the U.S. entities that hold /8 blocks.
"The inter-regional transfer policy has been recommended for adoption. It could be approved any day," Curran said. "It will definitely create some additional transfers. Again, you need to have some IPv4 address space even if you deploy IPv6 because you have to gateway back to old Internet users. Even companies going to IPv6 need IPv4 addresses."
Meanwhile, experts say just as many - if not more -- IPv4 address sales are going on outside of ARIN's 8.3 transfer process as there are being recorded by ARIN. That's because many of the original recipients of /8 IPv4 address blocks -- so-called "legacy" holders that received their IPv4 addresses before ARIN was created -- consider themselves outside ARIN's oversight.
"In ARIN's region, there are more transferred blocks than those being allocated directly by ARIN," says Peter Thimmesch, chairman of Addrex, a Herndon, Va.,-based IPv4 address marketplace that facilitated the Nortel IPv4 address sale to Microsoft. "This is because of ARIN's rules that you can only get allocations for a three-month period. If you're building a $3 billion data center, you are not going to rely on getting numbers every three months...Why not buy a couple of /12s [which have 1,048,576 IPv4 addresses]? It's about business continuity for the service providers."
Buyers of allocated-but-unused IPv4 addresses include service providers, mobile carriers, cloud software, web hosting and cable broadband companies.