On 01/08/2018 11:29, Tom Herbert wrote: > On Tue, Jul 31, 2018 at 2:21 PM, Ole Troan <[email protected]> wrote: >> Tom, >> >>> How is this story going to be different for IPv6? How do we ensure that >>> non-conformant implementation for IPv4 isn't just carried over so that >>> fragmentation, alternative protocols, and extension headers are viable on >>> the IPv6 Internet? >> >> I don’t think the IPv4 implementations are non-conformant. >> (With regards to the implications of A+P on the IPv4 architecture). >> >> For IPv6 one would fear that the same pressures that has led to IPv4 >> ossification applies. >> Well, what can we do? Apart from crypto, ensure that popular applications >> use the features, so they cannot be shut down? >> > Ole, > > That's the "use it or lose it" model of protocol features. TCP options > are firmly established as a required part of TCP protocol so there is > no way they could be obsoleted by external implemenation; IP options > on the other were never really required for IP operation so they are > considered expendable. The problem is that protocol features are often > defined before the application that would use them is built, so the > motivation to support all the features from the start isn't there. > This seems to be the case with extension headers, since only now does > there seem to be some serious proposals to use that functionality long > after the mechanism was first defined and IPv6 was deployed. In > reality, support of protocol features in the Internet is hardly ever > binary. Plain TCP/IPv4 packets are probably the only combination of > protocols that is guaranteed to work with probability approaching > 100%, however pretty much anything else works with some varying of > probability greater than 0% but less than 100% (like EH success rates > in RFC7872). To that end, I am wondering if the idea of Happy Eyeballs > could somehow be generalized to work with these other "non-standard" > features.
Generalised probing might be an answer, but (especially when there are multiple address pairs to probe) it can significantly impact start-up latency for a session. (Some dead work on that topic is at https://tools.ietf.org/html/draft-naderi-ipv6-probing .) Brian _______________________________________________ Int-area mailing list [email protected] https://www.ietf.org/mailman/listinfo/int-area
