On Tue, 31 Aug 2010, Jack Bates wrote:
Teredo usage isn't common enough on our network to warrant the work. Very few apps will activate it is my guess.
<http://ipv6.tele2.net/teredo_stats.php> As I stated, either your users are using your Teredo server, or they're using someone elses. Not running one yourself doesn't mean your users aren't running Teredo.
A customer is more likely (not always) to know when teredo has been activated. I've considered putting it in, but it is not friendly in many ways. 6to4 is usually running on routers in various pops. Teredo, I'd have to back feed to a server farm. This doesn't make for ideal traffic patterns even with bandwidth being so low.
Then the traffic is going to someone elses, how is that more optimal?
Then there is the "customer is unaware" fact. If the customer is unaware that their NAT is being pierced for IPv6 communication, then we have contributed to decreasing their security. For this reason, it might not be completely unwarranted for an ISP to block teredo all together. 6to4 doesn't suffer from this as there is no NAT traversal.
Blocking Teredo completely is a whole other discussion. Also, some NAT gateways will support a single device behind it doing Proto 41, so saying 6to4 has no NAT traversal and thus won't work beind NAT isn't true in all cases. -- Mikael Abrahamsson email: swmike@swm.pp.se