Does IPv6 Even Work?

With the free pool of IPv4 address space now exhausted, transitioning to IPv6 is set to become increasingly important. IPv6, however, isn't without its own set of challenges; and implementing it isn't as easy as simply flipping a switch.

One of the key places where IPv6 challenges are exposed is the interoperability lab at the University of New Hampshire (UNH-IOL). UNH-IOL sponsors plugfests and other interoperability events and initiatives that bring vendors together to help validate that their IPv6 solutions actually work together.

Tim Winters, senior manager for the UNH-IOL, told InternetNews.com that a number of surprises about IPv6 have emerged during recent plugfests.

"There were definitely surprises, I can say that the IETF standard we were using, the CE (Customer Edge) router draft was good and we didn't find any issues with the standard," Winters said. "What we did find are issues with the implementations."

Winters noted that vendors had been doing their own testing on devices, but when the same devices were brought into UNH-IOL and tested extensively, there were some issues.

"We had a lot of base stuff work, but when you start to get to the more complex things, it fell apart," Winters said.

DHCPv6 shows IPv6 poses problems in complex situations

The more complex items where vendor equipment had trouble with IPv6, ranged across a number of issues. One key problem area is DHCPv6, where Winters noted there were prefix delegation issues.

"Prefix delegation is important as that is how operators will tell a home what address they have," Winters said. "Our experience was not very good with that."

Winters added that up until recently there were no standards about how to do IPv6 on the LAN without the WAN. The IETF CE Router draft deals specifically with what is required on either side of a consumer set top box.

Overall the problem with DHCPv6 is the fact that it doesn't come standard with all platforms. Winters noted that neither Apple Mac OS X or Windows XP have DHCPv6 though Vista and Windows 7 do. He added that UNH-IOL has seen DHCPv6 implementation problems around timers and clients not renewing prefixes properly.

"It became painfully obvious to us that DHCPv6 is not that well deployed at this point," Winters said. "It's not so much a standards problem as it is an implementation problem."