With the Internet's largest-ever upgrade looming, network operators are using up address space based on the current standard -- known as IPv4 -- much faster than they are adopting IPv6, the next-generation standard.
The Internet's regional registries, which dole out blocks of IPv4 and IPv6 address space to carriers, will announce on Monday that less than 5% of the world's IPv4 address space remains unallocated.
IPv4 is the Internet's main communications protocol. It uses 32-bit addresses and can support 4.3 billion devices connected directly to the Internet. IPv6, on the other hand, uses 128-bit addresses and supports a virtually unlimited number of devices – 2 to the 128th power.
Overall, more than 200 million IPv4 addresses have been allocated from the so-called free pool of available IPv4 addresses since January 2010, with most of the addresses being snapped up by Asian carriers.
Allocation of the remaining blocks of IPv4 addresses is "imminent," according to Axel Pawlik, chairman of the Number Resource Organization, which represents the five regional registries.
"It is critical that all Internet stakeholders take definitive action now to ensure the timely adoption of IPv6," Pawlik said in a statement.
The NRO warns that the last IPv4 address blocks will be allocated from the free pool to the regional registries in early 2011. Experts predict that the registries will hand out these addresses to network operators by the end of 2011, leading to full-fledged depletion of IPv4 addresses.
Once IPv4 addresses are depleted, ISPs must give their new customers IPv6 addresses or use carrier-grade network address translation to share a single IPv4 address among multiple customers.
Despite the looming depletion of IPv4 address space, carriers are sending only a trickle of IPv6 traffic across their backbone networks.
Arbor Networks said last week in a blog post that IPv6 traffic represents less than one-twentieth of 1% of Internet traffic as of October 2010. This data came from 110 ISPs that participate in Arbor's ongoing Internet traffic measurement study.
Arbor found that most of the IPv6 traffic is via tunneling mechanisms -- primarily 6to4 -- rather than native IPv6 traffic.
This traffic data prompted Arbor Networks' Chief Scientist Craig Labovitz to write that "at this rate, we have years to go before any widespread v6 adoption."
Industry observers agree that the gap between the rate at which IPv4 addresses are being depleted and the rate of IPv6 adoption by carriers and enterprises appears to be widening.
"It comes down to the fact that people sitting at their computers or using their wireless devices are still being assigned IPv4 addresses and are looking at IPv4 content," says Chris Davis, senior director of corporate marketing communications for NTT America, which has offered native IPv6 services in the United States since 2004. "Users have to be given IPv6 addresses so they can access IPv6 traffic…You need the content to be on v6 and you need the eyeballs on v6."
Jason Livingood, executive director of Internet Systems at Comcast, says IPv6 traffic won't rise until more Web sites such as YouTube and Facebook start producing IPv6-based content. Comcast has an ongoing trial of IPv6 services that involves 7,000 commercial and resident customers and plans to offer commercial IPv6 services by 2012.
"We need content providers to step up and migrate to IPv6," Livingood says. "You will still see low levels of IPv6 traffic until end sites are v6-enabled."Some network operators are running into interoperability problems with their existing network gear when they try to deploy IPv6.
"It's difficult to adopt v6 because it can be a challenge to implement it on all of your devices," says Dave Seigel, vice president of IP Services Product Management at Global Crossing, which sells IPv6-based Internet access. "We're working with a managed customer that got serious about doing IPv6. We found all kinds of features with [routing protocols] BGP and EIRDP that are not supported in IPv6. Now, they've gone back to their router vendor, which is taking a lackadaisical approach that's slowing down our ability to migrate this customer. They're trying to be native IPv6, but they are completely stalled."