ARIN, the organisation that manages Internet IP address allocation for North America, is approaching the end of its supply of IPv4 addresses.
The largest block in organisation's remaining IPv4 address inventory is a single /11 (just under 2.1 million addresses).
The bulk of the remaining blocks of addresses available to organisations are /23 (142 blocks of addresses) and /24 (513 blocks) — but the organisation's public tally of its remaining IPv4 inventory doesn't take into account requests for blocks that have already been submitted.
Paul Wilson, the director general of the Asia-Pacific Network Information Centre (APNIC), which manages IP address allocation for the Asia Pacific, said that he believes the situation facing ARIN may have a flow-on effect that could boost local IPv6 adoption.
"ARIN is about to reach the completely predictable point where it won't have more addresses to distribute for Internet infrastructure growth," said Wilson.
However, although the exhaustion of ARIN's pool of addresses is predictable, the exact timing is hard to determine, he added, because of regional Internet registry's queue of requests for blocks of IPv4 addresses.
"The moment ARIN allocates the last available block, it actually doesn't make an immediate difference to anyone — it only makes a difference as service providers and enterprises decide that they might need some more IPv4 addresses, which could happen the next day or six months later," Wilson added.
"It's making news because of the size of the US market and the impact that will be assumed on the dotcom world," Wilson said.
In April 2011, APNIC handed out its final general-use /8 block of IPv4 addresses. The registry held back a /8 that it has been handing out addresses from since then.
"A decision was made then to hold back one pretty large block of IPv4 and to allocate it under a different regime after we'd run out of the rest of the supply," Wilson said.
"We've probably consumed about 25 per cent of it in the last three years."
"It was always intended to last for many years — it needs to last, in fact, right through the process of IPv6 deployment," he added.
APNIC members are able to obtain a maximum of two /22 blocks of addresses (for a total of 2044 addresses) from the registry.
"That rationing will go on and it's really essential for the healthy ongoing support of both v4 and v6 over the next probably 10 years," Wilson said.
ARIN took a slightly different approach. The organisation is withholding a contiguous /10 block but IPv4 addresses from it will only available to help with IPv6 deployment.
"Allocations and assignments from this block must be justified by immediate IPv6 deployment requirements," ARIN policy states.
"Examples of such needs include: IPv4 addresses for key dual stack DNS servers, and NAT-PT or NAT464 translators."
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ARIN will allocate blocks of addresses from a minimum size of /28 up to /24 from the /10.
Figures released by Google show that on May 17, 6.8 per cent of the Internet traffic flowing to the search giant was over IPv6.
Google pegs Australia's level of IPv6 adoption at 1.26 per cent of users, compared to 16.45 per cent in the US.
In September data released by World IPv6 Launch measured global adoption of IPv6 at about 4.5 per cent.
IPv4 supports around 4 billion IP addresses, compared to IPv6's 340 undecillion addresses.
APNIC's message to organisations remains to "think about IPv6 now", Wilson said.
"If you have anything to do with Internet products and services, you need think about IPv6 and ask your services providers, in whatever form, whatever service they're providing to you, what they're doing about v6," he said.
"Make sure you understand the answer and don't miss out on an opportunity to get v6-ready in your normal, routine process of hardware and software acquisition. Don't leave it unplanned until later."
"I think IPv6 is very well known as a concept and has been for the last 10 years. But in fact it was unfortunate, going back 10 years or so, that there was almost some over-promotion of IPv6 in the early days," Wilson said.
"There really has been phenomenon ever since then of people saying, 'Well we've heard about IPv6 for a long time and we're still doing okay without it, so what's changed?' And it's a good question — but the fact is, things have changed."
"They've changed very dramatically just in the last couple of years because of the shortage of IPv4 [addresses] which has really started to bite now," he added.
Although address sharing through network address translation (NAT) will in some cases remain an appealing alternative to IPv6 transition, "the longer that goes on, the more it's propagated, you actually have some serious costs in financial and performance terms," Wilson said.
On the flipside, potentially there are performance and cost advantages to IPv6 early movers, he said, particularly when it comes to content delivery.
"Now that we're really hitting a point where service providers themselves can't receive the addresses they need for their infrastructure, then that cost starts to escalate and be amplified through the network," he said.
"Anyone who depends on the internet is also depending on the provision of IPv6 at some point in the not-too-distant future and they really should be asking for IPv6 from their service providers," Wilson said.