IPv4 Internet addresses: 251 blocks down, 5 to go

A total of 33.6 million addresses are on their way to their ultimate users on the Net--meaning the last blocks of IPv4 addresses will be allocated soon. IPv6, hurry up, would ya?

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APNIC, which doles out Internet Protocol addresses in the Asia-Pacific region, got two of the remaining seven blocks of 16.8 million IPv4 addresses from central authority IANA.

Yesterday marked an important step toward the end of Internet plumbing as we know it.

Specifically, the Internet Assigned Numbers Authority (IANA) allocated two of the last seven blocks of Net addresses that use today's Internet Protocol version 4 (IPv4). That will trigger the automatic distribution soon of the last five, one each to the five regional Internet registries (RIR) that oversee the distribution of the numbers farther downstream, to the Internet service providers and other companies that actually need the IPv4 addresses.

It's hard to predict how long it will be before these eventual customers of IPv4 addresses will be unable to get them easily.

"The rate of further regional assignment will depend on regional demand, which is accelerating faster in some parts of the world (Asia/Pacific) than others (Africa)," said Alain Durand, director of software engineering at network equipment maker Juniper Networks. "Some service providers may exhaust their IPv4 addresses within 3 to 6 months, while others will exhaust them perhaps over a longer period, depending on the rate at which they are allocated."

It looks like the remaining five blocks will be allocated this week, if press invitations involving just about all the central overseers of the Internet are anything to judge by. "On Thursday, 3 February 2011, at 9:30 a.m. Eastern Standard Time (EST), the Number Resource Organization (NRO), along with the Internet Corporation for Assigned Names and Numbers (ICANN), the Internet Society (ISOC) and the Internet Architecture Board (IAB) will be holding a ceremony and press conference to make a significant announcement and to discuss the global transition to the next generation of Internet addresses," said an alert today from American Registry for Internet Numbers (ARIN), one of the five regional registries.

IP addresses are required for one computer to send data to another over the Internet. IPv4 allows for 4.3 billion addresses--2 to the 32nd power--but its successor, IPv6, allows 340 undecillion--2 to the 128th power, a vastly higher number. To be precise, 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses.

That new capacity excites network engineers, mobile phone carriers, and others running into IPv4 limits--but unfortunately the transition from IPv4 to IPv6 is a difficult one , because the two communication protocols are incompatible.

"The transition to IPv6 is not an easy one, not for ISPs, device makers, software developers, major websites, or customers themselves," said Jason Livingood, executive director of product platform engineering at Comcast, basing his opinion on the IPv6 trials Comcast ran with thousands of customers in 2010.

Experts expect a years-long transition to move fully to IPv6. During that time, Web site operators, Internet service providers, and others will have to gradually shift infrastructure from handling one protocol to handling both.

IPv4 address exhaustion drives this expensive transition. ISPs have long handled IPv4 constraints by sharing addresses dynamically among customers, and private networks can use a technology called network address translation (NAT) to share a single IP address among multiple computers. But the limits are worse for those who need fixed IPv4 addresses--a company launching a new Web site, for example.

IANA hands out IPv4 addresses in blocks of 16.8 million slash-eights, or /8s. That may sound like a lot of addresses, but in 2010, the RIRs went through 19 such blocks of them. That means that any efforts to conserve or redistribute remaining IPv4 addresses postpones the inevitable rather than fundamentally fixes the shortage. And some stopgap measures, such as "carrier-grade NAT" offered at the larger scale of an Internet service provider, can limit some Net services and impose bottlenecks.

"Having native IPv6 access is superior to tunneling [in which IPv6 data is sent over IPv4 networks] or doing one or more NATs in the network; direct, native access is faster and does not break certain applications, therefore resulting in a better end-user experience," Livingood said.

Some companies that got involved in the Internet early own entire /8s themselves and therefore have lots of unused IPv4 addresses--Hewlett-Packard got a second through its acquisition of Compaq, for example. Others with a /8 to themselves include the U.S. Postal Service, airline operations support company SITA, Prudential Securities, pharmaceutical giants Merck and Eli Lilly, the Massachusetts Institute of Technology, IBM, Apple, Xerox, AT&T, Level 3 Communications, General Electric, Ford Motor, and Halliburton.

The two slash-eights were distributed to Asia Pacific Network Information Centre (APNIC), the RIR for the Asia-Pacific region.

To give the world a chance to wrestle the IPv6 bull directly by the horns, the Internet Society is helping to organize the World IPv6 Day. On June 8, content providers such as Google and Yahoo and content distributors such as Akamai and Limelight Networks will offer their services over IPv6 for 24 hours for a collective evaluation and troubleshooting session.

Updated 4:24 a.m. PT and 4:52 a.m. PT with comment from Juniper Networks, Comcast, and ARIN.


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