What about IPv6 right here on earth?
Posted Feb 3, 2011 14:43 UTC (Thu) by farnz
In reply to: What about IPv6 right here on earth?
Parent article: LCA: Vint Cerf on re-engineering the Internet
We already have the situation you're discussing - I have today's IPv6 and IPv4, and can get to any cool sites that exist on IPv6 only.
Problem; there are no cool sites that are available on IPv6 and not IPv4. The reason? If I'm available on IPv4, close to 100% of my target market can get to me; if I'm not, only a tiny fraction of a percentage point can get to me. The economics are simply not there; in your hypothetical "IPv4++" world, the idiotic ISP would respond with "you need to do this very complex thing (at least as complex as deploying IPv6 is in today's world) to get access - it's the site's fault for using IPv4++". Net result? Everyone continues to use plain IPv4, ignoring the extended addresses possible in IPv4++, because you haven't solved the chicken and egg problem.
Note also that thanks to buggy systems, it's not safe to dual-stack your hosts by default. There are machines out there which think they have working IPv6 routing, but don't - about 0.1% of Google users last time I looked for the figures. So, real world experiments tell us that even co-existence of two protocols doesn't work properly; this leads to a thought experiment. How exactly does IPv4++ handle the case of two IPv4++ hosts with an IPv4 only segment in the middle, such that you can successfully talk IPv4 but not IPv4++?
Any answer that assumes that IPv4++ can transit the IPv4 segment has failed already - IPv6 can transit over IPv4 segments, yet we still see brokenness. Any answer that implies that an IPv4 only host cannot distinguish IPv4++ traffic from traditional IPv4 traffic has failed already - the most common form of brokenness in the IPv6 world is IPv6 in IPv4 tunnelling, where the IPv4 network deliberately blocks protocol 41, and there would have to be some similar indication that this is IPv4++ traffic.
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