"When one of our customers starts using IPv6, up to 40% of the traffic in and out of their home is IPv6," Brzozowski says, adding that the bulk of IPv6 traffic that Comcast sees is driven by YouTube, Netflix and the iTunes App Store. "Once IPv6 is on the home router, a lot of IPv6 starts to get consumed."
Comcast is focused on providing IPv6 to its residential broadband customers right now, but starting next year it will give its business customers IPv6 by default in order to help drive enterprise usage of the new protocol.
"Consumer electronics is the area that needs the greatest amount of work," Brzozowski says. "In residential, you can expect to see more penetration this year. Commercial usage will be a close third. You can expect to see expanded deployment as it relates to commercial services soon."
Limelight, a Tempe, Ariz.-based content delivery network that has been IPv6 enabled for two years, has seen its IPv6 customer base grow from three to 87 during the last three months. About 6% of Limelight's customers, including Microsoft, Netflix and NASA, are using IPv6.
Limelight is driving up IPv6 usage because it enables the protocol by default. All new customers get IPv6 unless they opt out.
"We've seen our IPv6 traffic go from a mere dribble - a couple megabits/sec - to about 2Gbps steady state, with spikes of 8Gbps. We've seen about 150% growth in two months," says Guy Tal, director of new markets for Limelight. "But it's still very small compared to our overall traffic. It's just over 0.1% of our traffic. . . If the trajectory holds, we're hoping to be at a couple percentage points of IPv6 traffic by the end of next year.''
Tal points out that most Limelight customers don't care if their application is running over IPv6 or IPv4; they just want it to work reliably and with high performance.
"The customers who do come and ask us about IPv6 tend to be the ones using our mobile monetization suite of services. These are the people concerned with iPads and Android devices," Tal says. "They want to know what new functionality they can enable because of IPv6. So mobile is driving IPv6 to some degree."