As long as none of your ipv6 traffic transits across anything from British Telecom as it is not supported on their 21st Century Network
<http://aaisp.blogspot.com/2008/10/bts-21st-century-network-ap parently-not.html>
The distinction between supported, and unsupported is that when something is supported by a company it means that the company has explicitly agreed to provide the supported feature and is getting paid for it. This is marketing/sales lingo. Given that NANOG is a technical forum, I don't know why you bring this up. Clearly we do technically support IPv6 on 21CN because we have customers using it. That's how we discovered a Cisco bug that causes certain IPv6 packets to be mangled, and like all bugs that ISPs find in vendor equipment, it is reported and will eventually get fixed. This illustrates why it is important to deploy IPv6 now, even if it is only for technically clued-in customers who will participate in bug finding, etc. There are a lot of technologies involved here, and clearly we need to exercise some of the access technologies like L2TP a lot more to shake out the bugs and get them fixed. That isn't something that any one ISP can do on their own. It requires every ISP to take IPv6 seriously enough that they deploy it in their labs and offices, then report every bug and issue to vendors asking them to make sure these things are fixed before the end of 2010. This is how the IPv4 Internet managed to scale through a period of 1500% annual growth. It was the cooperation between ISPs, vendors and researchers, mediated by NANOG as a forum, that enabled the Internet to become as important as it is today. --Michael Dillon