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0 pointsthrow0101d10d ago0 comments

Having partial deployment of IPv4x is no different than having partial deployment of IPv6: you have islands of it and have to fall back to the 'legacy' IPv4-plain protocol when the new protocol fails to connect:

* https://en.wikipedia.org/wiki/Happy_Eyeballs

Getting "free" new-protocol addresses is also nothing new:

> For any 32-bit global IPv4 address that is assigned to a host, a 48-bit 6to4 IPv6 prefix can be constructed for use by that host (and if applicable the network behind it) by appending the IPv4 address to 2002::/16.

> For example, the global IPv4 address 192.0.2.4 has the corresponding 6to4 prefix 2002:c000:0204::/48. This gives a prefix length of 48 bits, which leaves room for a 16-bit subnet field and 64 bit host addresses within the subnets.

* https://en.wikipedia.org/wiki/6to4

Translation boxes and tunnels are still needed for both IPv4x and IPv6.

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zadikian10d ago

Ok, I see what you mean then by 6to4 already supporting what v4x proposed, but that path wasn't taken either. It's a special feature with rare usage rather than the minimum default way of doing v6.

Dagger29d ago

We did take that path. If you zoom in on the start of https://www.google.co.uk/intl/en/ipv6/statistics.html you can see that 6to4+Teredo was more common than native until 2010. (Okay, that's combined with Teredo, but I think probably 6to4 is the majority of it because Windows will use 6to4 without needing a registry change or custom application behavior.)

You see it as a special feature with rare usage because it competed with native and lost. People overwhelmingly preferred deploying v6 natively instead of deploying 6to4. Obviously more people would be using it if it was the only option, but if you're trying to come up with an alternative to the way v6 went then "an approach that v6 took but which nobody wanted to use when native v6 was the alternative" might not be a very promising place to start.

zadikian9d ago

It's not like the v6 spec said, here are two options on equal footing, go figure out which is better. 6to4 was a temp bolt-on. I had to look up what things were actually like in 2010 because I really don't remember getting a 2002:, which brought me to rfc6343 that explained why exactly 6to4 suffered. A big part of it is that even a v6-enabled ISP didn't give you a 2002:, rather you were relying on anycast to reach a relay server. Why would an ISP or user ever want that mess? Either they do v6, or more likely they don't care and focus on v4.

So actually I take it back, 6to4 was pretty different from this ipv4x idea. I misunderstood and thought a v6-enabled ISP would give you a 2002: under 6to4, which you could later subdivide.

Ignoring that, say 6to4 were like v4x... The idea that those 2 years showed that native was preferable, that was among a small minority who even cared about v6 to begin with (0.25% at the time). This was a primary, not a final.

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