Comcast, Netflix report rise in IPv6 activity

Experts say IPv6 is attracting more users and content, but it's still a fraction of Internet traffic

The Internet industry is seeing evidence that more consumers, corporations and Web sites are deploying IPv6, the long-anticipated upgrade to the Internet’s main communications protocol, which is known as IPv4. But IPv6 remains a fraction of Internet traffic, and it’s nowhere near where it should be given the rapid depletion of IPv4 addresses.

ANAHEIM – The Internet industry is seeing evidence that more consumers, corporations and Web sites are deploying IPv6, the long-anticipated upgrade to the Internet's main communications protocol, which is known as IPv4. But IPv6 remains a fraction of Internet traffic, and it's nowhere near where it should be given the rapid depletion of IPv4 addresses.

Invisible IPv6 traffic poses serious network threat

Comcast, Netflix and APNIC were among the Internet companies and organizations that provided new statistics about IPv6 deployment at an Internet Society panel held here on Tuesday.

Standardized more than a decade ago, IPv6 is just starting to gain momentum in the United States.

IPv6 is needed because the current version of the Internet Protocol – known as IPv4 – is running out of address space. IPv4 uses 32-bit addresses and can support 4.3 billion devices connected directly to the Internet. IPv6, on the other hand, uses 128-bit addresses and supports a virtually unlimited number of devices.

Experts predict that the remaining IPv4 addresses will be distributed in 2012. In January, the Regional Internet Registries announced that fewer than 10% of IPv4 addresses remain unallocated.

When IPv4 addresses run out, carriers and enterprises must support IPv6 in order to add new customers or devices to their networks. Otherwise, they will need complex and expensive layers of network address translation (NAT) to share scarce IPv4 addresses among multiple users and devices.

Geoff Huston, chief scientist at APNIC and an expert on Internet infrastructure issues, says IPv6 now represents 1% of all Internet traffic.

"The good news is that from 2008 to 2010, in terms of routing IPv6, we were growing faster than we thought," Huston said, pointing out that the number of IPv6 entries in the core routing tables grew from 1,000 to 3,000 in that timeframe. However, the number of IPv4 routing table entries now tops 300,000.

Similarly, Huston said the number of Internet hosts that support IPv6 has reached 1%. While that sounds tiny, Arbor Networks estimated in August 2008 that IPv6 represented only .002% of Internet traffic.

"The relative use of IPv6 has increased over the last four years to hit 1% of traffic," Huston said. He added that one cause for optimism is that "the folks in the transit ISP industry show that they get IPv6."

Comcast, which was the first ISP in the United States to announce an IPv6 trial, said it was surprised by the number of people who signed up to participate in the trial, which begins in April.

"We had 5,500 volunteers sign up in a matter of days," said Jason Livingood, executive director of Internet systems engineering at Comcast. "Not only did we get more volunteers than we expected, but we had people switching ISPs to participate in this trial. We also saw a lot of interest from our corporate customers, particularly for our fiber-based commercial service that is IPv6 ready."

In another sign of IPv6 activity, Comcast said the amount of traffic on its network that uses an IPv6 tunneling mechanism known as 6to4 grew 500% in the last 45 days. 6to4 is one way to encapsulate IPv6 packets inside IPv4 packets for transport over an IPv4 network.

"A lot of people are doing tunneling. That means a lot of people are experimenting with IPv6, but can't buy it from their ISPs," Livingood said, adding that these people are potential customers for Comcast's IPv6 service.

Livingood said Comcast's commercial IPv6 service will offer higher performance than 6to4 tunneling.

"The main issue around tunneling is performance," Livingood said. "Most 6to4 tunnels go through the University of Wisconsin at Madison [which has a 6to4 relay routing service] to the eventual site. That's not as great as going direct."

Livingood concedes that the amount of 6to4 traffic is "statistically a very small number, but we are noticing the growth."

Another statistic Comcast is tracking is the number of high-traffic Web sites that are accessible via IPv6. In February, Comcast noticed a boost in these numbers for the top 1,000 Web sites.

Among the Top 10 Web sites, 20% are now accessible via IPv6, which is double the amount from a month ago. Similarly, the number of Top 100 Web sites that support IPv6 grew sixfold from 3% to 18%, and the number of Top 1,000 Web sites that support IPv6 grew fourfold from 2% to 8%.

"We looked at the Alexa Top Million Web sites in terms of their reachability and whether they were able to respond to IPv6. The number is steadily increasing," Livingood says.

Dave Temkin, network engineering manager with Netflix, said the company's IPv6 service is attracting more customers, but that it is still less than 1% of its traffic.

"We rely on content delivery networks. We worked with Limelight, which has full IPv6 capability, for our service. Now we are pushing on the other CDNs like Akamai and Level 3 to offer IPv6," Temkin said, adding that this will help drive more IPv6 traffic to Netfix.

Temkin said the business drivers for IPv6 are getting stronger, as content providers like Netflix are able to provide higher performance via IPv6 than they can to IPv4 users traversing tunnels or NATs.

"We see this is a net neutrality issue," Temkin explained. "If our customers are forced to go through some carrier-grade NAT, you have a spot of contention. Regardless of whether that's intentional or not, you have to start to differentiate services that are IPv6 vs. IPv4. If our service performs better over IPv6 than IPv4, we could lose market share over that….That is a very strong driver form our side, and we are keenly aware of it."

Temkin said the only surprise that Netflix has seen with its IPv6 deployment is how easy it was.

"For our internal integration and our Web site and our corporate network, we worked with a [content delivery network] – in our case it was Limelight – and it was actually very straightforward," Temkin said.

While the panelists were optimistic about the signs of IPv6 growth, they warned that much more activity needs to occur if the Internet infrastructure is to be ready when IPv4 addresses run out in 2012.

"As of March 2010, we're at 1% or thereabouts," Huston said. "In 2012, we will all have a problem because the current mechanism of distributing IPv4 addresses will be over. Last year, [we] needed 200 million of them. As of 2012, they will be a lot harder to get."

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