"People do want to buy the larger blocks of addresses and they are not sure yet on how to do it," von Loewis says. "The policies are evolving all the time ... It's somewhat complicated."
The rules of how IPv4 addresses can be sold are still being clarified.
Microsoft agreed last week to transfer these IPv4 addresses using policies established by the American Registry for Internet Numbers (ARIN), one of five Regional Internet Registries that dole out IPv4 and next-generation IPv6 address space to ISPs, enterprises and other network operators.
ARIN says it has authority to approve all sales and other transfers for IPv4 address space -- even legacy address space given out prior to ARIN's founding in 1997-- in the United States, Canada and parts of the Caribbean.
ARIN's policy for overseeing IPv4 address sales is this in a nutshell: In order for an organization to sell IPv4 addresses, it has to prove to ARIN that the addresses are registered to that organization. The buyer has to prove that it is a valid recipient of the IPv4 address space, including demonstrating that it has the need to use up the addresses over the next 12 months.
"Whether we're talking about a transfer or a sale, at the end of the day these get transferred as updates to the entries in ARIN's registry database," says ARIN President and CEO John Curran. "Transfers occur after we receive a request and approve it."
ARIN is encouraging the nascent market for IPv4 address trading.
"Our job is to make sure there is good utilization of address space," Curran says. "If there's a market for IPv4 addresses, people who have some unused addresses and might have to work to get it freed up will have an incentive to do so. That means the address space will be better utilized."
Curran says ARIN has seen a modest increase in IPv4 address transfer activity in the last few months, as IPv4 depletion has become a more urgent issue.
Curran says he anticipates "there will be dozens of organizations that will try to match people with addresses with those who need addresses. ... The more organizations that help people find address space, the better. It doesn't do us any good to all be running out of address space and have some idle."
ARIN adopted this IPv4 address transfer policy 18 months ago because it was worried about the development of a black market for IPv4 addresses. But ARIN's transfer process is so new that "it's really a murky area," Arbor Networks' Labovitz says.
Sign up for Computerworld eNewsletters.