Cisco Extends IPv6

No, the sky isn’t falling yet, but for those watching the rapidly dwindling IP address space, it will soon: IPv4 address space is almost completely exhausted and IPv6 has yet to become widely adopted on a global scale.

To help address the issue, networking giant Cisco (NASDAQ: CSCO) is now rolling out new IPv6 services to carriers in an effort to help ease the migration from IPv4.

IPv6, the successor technology to IPv4, has a 128-bit address space, enabling it to handle far more addresses than the 4.3 billion addresses provided for through IPv4’s 32-bit address space.

For Cisco, the new efforts are not about simply enabling IPv6 but rather about enabling migration.

“IPv6 is and has been supported in Cisco IOS since it was standardized in late 1990, early 2000,” Mike Capuano, director of service provider marketing of routing and switching solutions at Cisco, told “In fact virtually all Cisco platforms support both IPv6 and IPv4 simultaneously as dual-stack.”

“However, what we are introducing today is a solution on the Cisco CRS-1 Carrier Routing System and Cisco ASR series to help with a new problem — IPv4 exhaust,” he added.

Capuano explained that moving to IPv6 isn’t typically as easy simply turning on IPv6 addressing on equipment. He noted that the original migration strategy was supposed to be dual-stack, by which both IPv4 and IPv6 to run at the same time. However, this approach depended on the industry being at an approximately 50 percent migration level by this point.

Instead, according to Capuano, only 1 percent of the Internet today runs IPv6.

“Now IPv4 run-out is imminent in a couple of years, and then the dual-stack transition path will no longer be an option because you need an IPv4 address on one side and an IPv6 on the other,” Capuano said.

He’s not alone in cautioning about the shortage. In the U.S, the federal government adopted a 2008 mandate to have an IPv6-capable network, though usage of IPv6 in other areas, such as the corporate environment, has to date remained very low.

One of the challenges is ensuring that IPv4 is interoperable with IPv6. Capuano said Cisco is now offering a technology that preserves the existing IPv4 mode of operations by using Large-Scale Network Address Translation (LSN) to allow service providers to use private addresses in their infrastructure network.

NAT (Network Address Translation) is often thought of as a technology that can be used to extend IPv4 by providing private IP addresses to local networks. Large-Scale NAT goes a step further by extending address translation to carrier scale.

In addition to LSN, the Cisco IPv6 solution also provides the ability to run IPv6 over an IPv4 tunnel (known as “6-over-4”) as well as running IPv4 over an IPv6 tunnel (or “4-over-6”), leveraging a technology called Address Family Translation (AFT).

“NAT is needed to extend the current mode of operations in IPv4 and hence is a part of the preserve approach of the solution,” Capuano said. “AFT and Tunneling are other key Cisco carrier-grade IPv6 technologies, which form a part of the prepare approach.”

With NAT and AFT, Capuano said that IPv4 and IPv6 can co-exist in a various scenarios. He added that eventually the goal is to get to an all-IPv6 (or mostly IPv6) network infrastructure, at which point we will no longer need any address translation, whether NAT or AFT.

Hardware and software

Enabling IPv4 to IPv6 migration for carriers involves both hardware and software. For Cisco’s flagship carrier router, the CRS-1, the company is introducing a new blade called the Carrier-Grade Services Engine.

According to Capuano, the new blade is capable of handling tens of terabits of throughput and hundreds of millions of translations for the Cisco Carrier-Grade IPv6 solution.

On Cisco’s ASR router series, the IPv6 services are being enabled with new software functionality.

While the pending exhaustion of IPv4 address space has been known for several years, there has been little urgency, especially in North America to migrate. Capuano explained that IPv6 adoption is now a carrot-and-stick situation.

“The stick is that IPv4 is running out and it is a serious problem as the number of devices is growing rapidly,” Capuano said. “The carrot is there are many new applications where service providers might play, like smart grid, sensor networks, home security, and more … all require a lot of addresses.”

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