Arguably, transitions technologies like 6to4 and Teredo have already achieved their purpose. My goal at the time, more than 10 years ago, was to break the "chicken and egg" deadlock between application developers and network administrators. That's why I spent such energy on making 6to4 easy to deploy, or defining Teredo. Transitions technologies convinced developers that applications could be developed for IPv6 without waiting for every network to be ready, and applications were indeed developed by Microsoft and others. Network administrators in the meantime started deploying IPv6, and the presence of applications arguably helped somewhat -- although I am sure network administrators add many other motivations. We are now observing a strong pushback, because massive use of tunneling technologies makes networks harder to manage. Wide scale deployment of self-configuring technologies makes levels of services less predictable, and errors are hard to correct. Self-configuring technologies rely largely on the good will of others, which is easier to find during a pioneering phase. Arguably, we are beyond the pioneering phase for IPv6. I understand Keith's point of view, but it is probably time to start progressively rolling back the transition technologies. 6to4 is the weakest of these technologies. It does not traverse NAT, it does not include configuration verification tests, and it uses asymmetric paths. It makes sense to start the rollback with 6to4. -- Christian Huitema _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf