Cisco Readies For The Day Current Internet Addresses Run Out

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With the Internet's supply of IPv4 addresses set to run out in about two years, Cisco Systems is pitching service providers on a "carrier-grade" network-address translation solution to help them in the transition to the next-generation IPv6 protocol.

The current Internet Protocol version -- known as IPv4 -- provides only 4.29 billion unique addresses. Those are expected to be depleted as soon as the fall of 2011, according to Internet industry experts. At that point, providers will be forced to begin more widely using IPv6, which provides an astronomically large address space of 2 to the 128th power.

The issue is that only 1% of the Internet has been converted to IPv6, according to Cisco, so ISPs need a way to translate between the two incompatible protocols.

"The problem in our windshield right now is IPv4 exhaust," said Mike Capuano, director of marketing for Cisco's service provider routing and switching group. "There's a new problem we're going to run into because the transition to IPv6 is taking so long."

There's no danger of running out of IPv6 addresses, perhaps ever. Here's one analogy: Assuming the Earth were made entirely out of 1 cubic millimeter grains of sand, IPv6's 128-bit address space would provide enough unique addresses for all the grains of sand in 300 million Earth-size planets.

Cisco has developed network-address translation capabilities for its CRS-1 core routers and ASR edge routers. A hardware blade for the CRS-1 platform, which Cisco calls the "carrier-grade services engine," provides up to 20 million address translations. The solution enables IPv4-only devices to communicate with IPv6-only devices, and vice versa, and also provides large-scale IPv4 network address translation.

Initially, Cisco expects ISPs to use that to provide public IPv4 to private IPv4 translation, to maximize the existing address space. A single publicly routable IPv4 address could provide service to 200 or more customers, the company estimated.

"You can't just flash-cut over to IPv6, so you have to do a reasonable step-wise translation," Capuano said.

The American Registry for Internet Numbers, which distributes large blocks of IP address space to ISPs and other organizations in North America and parts of the Caribbean, began allocating IPv6 blocks to providers in 1999.

Although some providers, including Comcast, have begun supporting IPv6 in their own networks, there hasn't been a big uptake of the next-generation protocol yet, said Richard Jimmerson, ARIN's CIO.

"A lot of people predicted that IPv6 wouldn't take off until the IPv4 address space has nearly been tapped out," he said. Providers "are going to flip on IPv6 -- the alternative is that they can't grow their businesses."

Cisco will make the large-scale address translation features available in early 2010. The vendor has not determined pricing. Cisco is testing the technology with several providers worldwide, including Japan's NTT Communications, France's Free and China's Cernet.

Capuano said competing solutions are approaching IPv4-to-IPv6 network-address translation with standalone appliances, which, he argued, makes them more difficult to manage.

ARIN's Jimmerson said some providers "will not be able to do a good job on the translation," and that it's foreseeable some IPv6 queries will "leak out natively" to the Internet. To address this issue, ARIN is encouraging content providers to run Web servers with both IPv4 and IPv6 protocol stacks.

"Over time, when IPv6 becomes larger than IPv4, you'll see more pure IPv6 networks," Jimmerson said.

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