The Internet's biggest content providers including Yahoo, Facebook and Google are reporting a significant decline in their measurements of "IPv6 brokenness," a term that describes end users with misconfigured systems that can't access websites supporting IPv6.

Worries about IPv6 brokenness have been a major stumbling block for content providers wanting to deploy IPv6, an emerging standard that solves the looming address shortage with the Internet's current standard known as IPv4.

Some of the Internet's most popular websites shared details about their latest IPv6 brokenness measurements at a meeting of the Internet Engineering Task Force (IETF) held this week.

Problem fixed?

Experts say the IPv6 brokenness problem is lessening for two reasons: Browsers such as Google's Chrome have enabled a new feature called "fast fallback,'' which identifies users suffering from IPv6 brokenness and automatically reconfigures their access to IPv4.

Also, popular websites such as Google, Facebook and Yahoo have engaged in a massive outreach programme to users that they feared would suffer from IPv6 brokenness, offering them automated tools to identify and fix the problem. This outreach programme coincided with World IPv6 Day, a 24 hour trial of IPv6 that was held on June 8.

"Yes, we've pretty much fixed the IPv6 brokenness problem," said IETF Chairman Russ Housley. "It's because of browsers with the new 'fast fix' and the outreach surrounding World IPv6 Day."

"IPv6 brokenness is a declining concern generally, as host and browsers implementations deploy fixes," agreed Christopher Palmer, an engineer with Microsoft's Windows Networking team. He added that Microsoft "received five calls about IPv6 brokenness on World IPv6 Day, and four of them weren't real."

Users suffering from IPv6 brokenness experience slowdowns or have trouble connecting to IPv6-enabled websites because they have misconfigured or misbehaving network equipment, primarily in their home networks. Corporate users also can experience IPv6 brokenness because of faulty firewall settings. For end users with IPv6 brokenness, some websites that support IPv6 and IPv4 simultaneously in what's called a dual stack configuration appear to be suffering from an outage.

Prior to World IPv6 Day, the Internet Society estimated that as many as 0.05% of Internet users would suffer from IPv6 brokenness during that 24 hour trial. While that percentage may sound miniscule, it actually represents 1 million of the Internet's estimated 2 billion users.

Negligible worries

Yahoo in particular worried publicly about the threat of IPv6 brokenness, but now claims those worries were for naught. Igor Gashinsky, a principal architect with Yahoo, said the company's measurements of IPv6 brokenness have declined threefold in the last 21 months, from 0.078% to 0.022%.

"During World IPv6 Day, our breakage stats remained the same at 0.022%," Gashinsky said.

Yahoo's findings of declining IPv6 brokenness are holding up for other Internet players, including Facebook and Google.

Facebook's measurements of IPv6 brokenness have fallen from 0.03% of Internet users down to 0.02% since World IPv6 Day, according to Donn Lee from Facebook's network engineering team.

"We estimate that approximately 0.02% of our users will have slowness in loading Facebook if we turn on with IPv6 permanently," Lee said. "That's what dual stack brokenness means to us."

Lee said Facebook sent a message to users that it thought might suffer from IPv6 brokenness prior to World IPv6 Day. He said it appears that many of these users are fixing the problem themselves.

"Brokenness seems to be declining after World IPv6 Day. It surprises me," Lee said. "I did not expect any brokenness to change. I thought the users would suffer in silence... But it turns out that without any changes to our instrumentation, the dual stack brokenness is slowly going down."

User education

Lorenzo Colitti, a network engineer with Google, said the most important thing Google did for World IPv6 Day was to warn users that it thought would suffer from IPv6 brokenness ahead of time, and encourage them to diagnose their systems.

"We put a drop-down box at the top of the Search page telling users that we're testing IPv6 on June 8 and that they should click here to find out if they're ready," Colitti said. "We prepared an IPv6 test site for them to use."

Google also added what it calls "fast fallback" from IPv6 to IPv4 service in its Chrome browser.

"IPv6 brokenness went down 80% to 90% in the Chrome browser," Colitti said. "If all browsers behaved like that, we would just publish our Quad A [IPv6] record. Browsers with versions of fast fallback were 99.9995% as reliable as IPv4. We saw similar behaviour in Firefox 7. Apple is adding this in OS X Lion. All we need is Internet Explorer to follow suit."

Palmer wouldn't comment on when Microsoft would offer a patch for Internet Explorer to handle "fast fallback," but he indicated Microsoft planned to address IPv6 brokenness in an upcoming version of the Windows operating system.

IPv6 represents the biggest upgrade to the Internet infrastructure in its 40 year history. That's because IPv6 is not backward compatible with IPv4, so website operators have to upgrade their network equipment and software to support IPv6 traffic.

The IETF created IPv6 a decade ago because the Internet is running out of addresses using IPv4. The free pool of unassigned IPv4 addresses expired in February, and in April the Asia Pacific region ran out of all but a few IPv4 addresses being held in reserve for startups. The American Registry for Internet Numbers (ARIN), which doles out IP addresses to network operators in North America, says it will deplete its supply of IPv4 addresses this fall.

IPv4 uses 32-bit addresses and can support 4.3 billion devices connected directly to the Internet, but IPv6 uses 128-bit addresses and can connect up a virtually unlimited number of devices: 2 to the 128th power.

IPv6 offers the promise of faster, less costly Internet services than the alternative, which is to extend the life of IPv4 using network address translation devices.