Falling back to IPv4 if IPv6 does not succeed is literally the day 1 behavior of IPv6 transition. Except for TCP it may take a few minutes which is clearly unacceptable. So we wrote RFC6555. It still doesn’t help in the case of PMTUD black holes, but fixes the most obvious blunders. It’s still that you need to have a common protocol between the two endpoints, there is no way around it - so he just rephrases what is essentially “transition via dual stack” strategy but with his own words.
Once again - djb is a brilliant cryptographer, an application designer and coder, and I respect him very much for his genius there.
But I maintain that his thoughts on the topic of IPv6 transition unfortunately do not share this property, and reveal that he is completely ignorant of a lot of practical factors that are at play in that context.
Comments
Falling back to IPv4 if IPv6 does not succeed is literally the day 1 behavior of IPv6 transition. Except for TCP it may take a few minutes which is clearly unacceptable. So we wrote RFC6555. It still doesn’t help in the case of PMTUD black holes, but fixes the most obvious blunders. It’s still that you need to have a common protocol between the two endpoints, there is no way around it - so he just rephrases what is essentially “transition via dual stack” strategy but with his own words.
Once again - djb is a brilliant cryptographer, an application designer and coder, and I respect him very much for his genius there.
But I maintain that his thoughts on the topic of IPv6 transition unfortunately do not share this property, and reveal that he is completely ignorant of a lot of practical factors that are at play in that context.