The U.S. is on track to run out of IPv4 addresses sometime this summer, although most everyday Internet users aren't likely to notice any changes. For Internet service providers (ISPs), however, IPv4 exhaustion means they have to begin -- if they haven't already -- making plans to transition to IPv6.
First deployed in 1981, when academics were virtually the only people online, the 32-bit-based IPv4 protocol created the potential for nearly 4.3 billion individual addresses, which was far more than enough at the time. But with an estimated three billion people on the Internet today, the remaining IPv4 addresses are being quickly scooped up. (IP addresses identify not just computers but printers, Xboxes and other devices connected to the network.)
Such IP address exhaustion should no longer be a problem once ISPs and enterprises convert to IPv6, the 128-bit number protocol first deployed in 1999 to replace IPv4. IPv6 will support 340 trillion trillion trillion possible addresses, but organizations currently using IPv4 will have to upgrade their networks to be able to take advantage of that much larger address pool.
Like a River Running Dry
Available blocks of IPv4 addresses have already run out in Asia and Europe, but even in those areas the impact isn't really visible, Dan York with the Internet Society's Deploy360 Programme told us. ISPs in those geographies still tend to have ample supplies of IPv4 addresses on hand, he said. What address exhaustion means is that they can no longer obtain any new IPv4 blocks from Internet registries.
"What we do know is that service providers in the region (Asia and Europe) are having to add complexity to their networks in such forms as additional layers of network address translation," York said. "Ultimately this added complexity may result in latency and other network effects that could impact services that are sensitive to real-time communication such as VoIP or gaming. Longer term, it will impact the ability of service providers to easily bring on more and more devices."
York compared today's situation in the U.S. to that of a river running out of water at its source: water that has already entered the river will continue to flow downstream to places that are used to seeing it, but eventually the supply downstream will dwindle and disappear. In the U.S., ISPs "have large pools they can use right now," York said. "They will have some for some period of time."
The American Registry for Internet Numbers (ARIN), which is responsible for distributing IP addresses in the U.S., has been following a four-phase plan to handle the depleting number of IPv4 addresses, giving an increasing level of scrutiny to requests in each subsequent phase. It is currently in the fourth phase of that plan.
Networks for the Next Billion Online
"IPv4 was never intended to service the needs of a global, commercial Internet," said Richard Jimmerson, Chief Information Officer for ARIN. "It was clear in the mid-1990s that when the Internet went global and commercial that IPv4 would not scale to meet that need. As a result, IPv6 was created and it was designed to suit the needs of a global communications infrastructure. We do not expect to experience a depletion event with IPv6 any time soon, like we are going through today with IPv4."
While it's difficult to estimate how many organizations have made the transition to IPv6, the Internet Society's World IPv6 Launch measurements page shows how far along leading network operators are in the change. As of April 8, for example, Verizon Wireless had just over 66 percent of its traffic using IPv6, while the T-Mobile USA level stood at 53.6 percent.
Major Internet companies like Facebook and Google also began planning for the transition several years ago, and are well along toward adopting IPv6 as a standard. Facebook, for example, is already using an all-IPv6 network for internal needs, and expects to have 100 percent of its network on IPv6 by the end of this quarter. The social networking giant reported that users on IPv6 are seeing News Feeds load 24 to 40 percent faster than those on IPv4.
"Facebook and Google are strongly moving forward," York said. "They want to be sure to be responsive to the next billion people to come online."