"Most routers don't have support for counting IPv6 traffic separate from IPv4 traffic on their physical interface counters," explains Dorian Kim, vice president of IP engineering, Global IP Network at NTT America. "By and large, bits are bits to interfaces, and there's been no particular driver for us to track IPv4 and IPv6 separately, especially when measuring IPv6 in the network requires one to instrument NetFlow 9 collection of traffic from the routers."
Kim says NetFlow 9 is "the most likely way we'll be able to account for IPv6 traffic separately from IPv4 traffic. ...We are working with our equipment vendors to have NetFlow 9 export capabilities across all of our network, but that is something that'll happen over time."
NTT America isn't the only ISP that hasn't been able to deploy NetFlow 9. "I heard from a significant cable operator that they don't run NetFlow 9 and hence can't measure IPv6 flows," Levy says.
One reason most carriers don't have NetFlow 9 gathering statistics across their peering and edge routers is because it can cost millions of dollars to deploy.
"It's pretty expensive to do complete traffic measurement across your entire network," says Siegel, pointing out that Global Crossing has deployed NetFlow 9 in Europe. "It's kind of a luxury."
Siegel says Global Crossing will have NetFlow 9 deployed across a third of its network footprint by the end of the year. He says the carrier has run into trouble deploying NetFlow 9, including the discovery that its edge routers didn't have enough horsepower to collect data on every port, resulting in a limited view of traffic patterns. Global Crossing plans to use NetFlow 9 to create customized billing models rather than to monitor IPv6, which represents only 0.1 percent of its traffic in Europe.
"We only started making [traffic measurement] more of a priority lately as a way of analyzing customer profitability," Siegel says, adding that measuring IPv6 traffic flows is not a driver for the purchase. "The variability of how a customer is using the network plays an extremely large role in whether or not we see profit at any given price point. That's our primary purpose behind ponying up the cash to buy the [NetFlow 9] software and the hardware platform."
Some experts argue that measuring IPv6 traffic with NetFlow 9 is not the best way to determine the rate at which IPv6 is being adopted.
Traffic is too ephemeral, says Geoff Huston, chief scientist at APNIC, the regional Internet registry for the Asia Pacific Region. Huston prefers to measure how many end users have IPv6 enabled on their devices. He points out that this figure is as disappointingly low as the Arbor Networks IPv6 traffic data.
"When you look at end users and their predilection to use IPv6, the story is pretty bad," Huston says. "I see 0.2 percent of clients prefer to use IPv6 on a dual-stack environment. ... Since November, that number has risen by a little under 0.1 percent. Yes, that's a 50 percent jump. No, these are still tiny numbers and cannot be interpreted as a wave of IPv6 adoption."
Huston says end user IPv6 adoption rates are not rising faster because recent versions of the Windows and Mac operating systems prefer to use IPv4 in dual stack environments where IPv4 and IPv6 are running side-by-side, rather than using IPv6-based tunneling techniques such as 6to4 and Teredo.