It just got a little harder to link a new computer to the Internet in the US and Canada.
The Internet runs atop a standard called Internet Protocol version 4 (IPv4), and every device using the Internet needs an IPv4 address. Those addresses are running out, though, and the authority that doles out IPv4 addresses just entered a new, more restrictive phase for those who need them.
This doesn't affect the average person, but it does affect Internet service providers, businesses that want to launch new online services, and Internet registrar companies that set up new domain names for customers.
"We are approaching runout of IPv4 space availability in this region," said John Curran, president of American Registry for Internet Numbers (ARIN), in a mailing list announcement Wednesday. ARIN is down to its last 16.7 million addresses -- down from twice that number last August.
Accordingly, it began new restrictions in the US and Canada as part of phase 4 of its IPv4 countdown. Those wanting any blocks of IP addresses now need the approval of ARIN reviewers. (There are four other registries around the world that allocate IPv4 addresses for other regions.)
The exhaustion of IPv4 addresses doesn't mean anything as dire as an end to the Internet, but it does signify the increasing complexity and expense of keeping the existing architecture running.
IPv4 addresses are 32-bit numbers, which means there are about 4.3 billion for the entire world. Facebook.com's IPv4 address is 18.104.22.168, for example. The numeric addresses are used to route data packets across to their destinations.
The exhaustion of IPv4 addresses is no surprise -- it's been approaching for decades. That's why the Internet Engineering Task Force (IETF) long ago, which is vastly more capacious by virtue of 128-bit address numbers. Over IPv6, Facebook.com's address is 2a03:2880:2110:df07:face:b00c::1 -- a number that's written in hexadecimal and therefore can incorporate a sequence of digits that in a bit of nerd humor read "face:b00c."
Companies like Google, Facebook, Yahoo, and Microsoft are. They've had , but the big problem is that it's not possible to scrap IPv4 until everyone can use IPv6. Today, many people's computers link to the Internet only via IPv4 and many services they try to reach only are available over IPv4. That's led to increasingly complicated mechanisms for sharing IPv4 address among multiple devices, and it means companies investing in IPv6 infrastructure don't necessarily get an obvious payoff.
The steady decline in IPv4 addresses does serve as an incentive, according to a survey of 51 wired and wireless Internet service providers by Incognito Software published Tuesday.
"Overwhelmingly, service providers are adopting IPv6 because they are running out of IPv4," Incognito concluded. About 83 percent of respondents listed that as a reason, more than twice as many as the second-ranked incentive, distrust of the network address translation (NAT) technology used to share IPv4 addresses and therefore extend IPv4's lifespan.
ARIN entered the fourth phase of its IPv4 countdown when its supply IPv4 address supply dropped down to its last block called a /8 -- 16,777,214 IP addresses. That triggers heavier scrutiny of IPv4 requests -- especially of a request for a /15 block with 131,070 IP addresses.
"All requests of any size will be subject to team review, and requests for /15 or larger will require department director approval," ARIN said.