Factors, actions influencing the possibility/timing of IDR for IPv6-basedrouting domains?

[Erik Kline]

> But, those farms know the same thing Google knows, which is that
> eventually there's going to be IPv6-only clients out there, and
> they don't want those clients complaining to their own customers,
> and their own customers perhaps leaving without even saying anything.
> Plus, you never know exactly what Google is going to use as search
> criteria.  Google is spending big bucks on their own IPv6 deployment,
> and it wouldn't be farfetched to imagine that Google might one day
> quietly slip "Reachable by both IPv4 and IPv6" on to their list of
> items that increase your page ranking.

One thing we try to consider is that the only thing you can assume
about the IP connectivity of a user making a request is the protocol
over which the request was made.  In other words, if a request comes
in over IPv4 you can assume the user effectively has v4 access, and
similarly for v6.  Right now you can be *statistically* assured that a
user making a v6 request has v4, but that is not 100% true now, nor
will it always remain even a strong likelihood.  (Of course, in
theory, you can correlate several out-of-band factors to increase the
accuracy of any guess about non-request-protocol availability, but why
go to all that work.)  So if a request comes in over v6 we serve v6
cache links in the response (bugs not withstanding :).

It's theoretically possible that if the IPv4 web corpus and the IPv6
web corpus become significantly divergent that some accommodation
might be made.  It might be more akin to search results in a language
that wasn't your detected native language, though.  Too early to tell.

On a different note: one thing that will be nice when v6 becomes
popular with hosting providers: everyone can get a static v6 address
and hence an SSL cert (i.e. we won't need SNI).

-Erik