No more IPv4 addresses

Last seven IPv4 address blocks assigned

The Internet has run out of IPv4 address space.


The Internet Assigned Numbers Authority (IANA) assigned two of the remaining blocks of IPv4 addresses - each containing 16.7 million addresses - to the Asia Pacific Network Information Centre (APNIC) on Tuesday, as predicted.

This action sparks an immediate distribution of the remaining five blocks of IPv4 address space, with one block going to each of the five Regional Internet Registries (RIR).

The American Registry for Internet Numbers (ARIN), which doles out IPv4 addresses to carriers and other network operators in North America, is expected to receive its last allotment of IPv4 addresses today.

Experts say it will take anywhere from three to seven months for the registries to distribute the remaining IPv4 addresses to carriers.

Once the registries hand out all of the IPv4 addresses, network operators must either deploy complex, expensive network address translation technologies to share IPv4 addresses among multiple users or adopt the next-generation of the Internet Protocol called IPv6.

PANIC TIME QUIZ: How prepared are you for IPv6?

The IANA distributions of IPv4 addresses hit a bulls-eye mark on predictions that Internet experts made that the free pool of IPv4 addresses would exhaust on Feb. 1, 2011.

Internet policymakers said they will host a press conference on Thursday to discuss the depletion of the IPv4 address space and what it means for future growth of the Internet.

The press conference, which will be held in Miami, will feature speakers from IANA, an umbrella group of the RIRs known as the Number Resource Organization, the Internet Corporation for Assigned Names and Numbers (ICANN), the Internet Architecture Board and the Internet Society.

Now that IPv4 addresses are gone, Internet policymakers will be ratcheting up the pressure on network operators to migrate quickly to IPv6.


Created 30 years ago, IPv4 has a 32-bit addressing scheme and can support approximately 4.3 billion devices connected directly to the Internet. The Internet engineering community has known for a decade that IPv4 addresses would eventually run out, and so they created IPv6 as an upgrade to IPv4.

IPv6 features a 128-bit addressing scheme and can support vastly more devices -- 2 to the 128th power. IPv6 also includes built-in security with IPsec and easier management through autoconfiguration of devices.

Read more about lan and wan in Network World's LAN & WAN section.

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Carolyn Duffy Marsan

Network World
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