On Jun 8, 2011, at 7:05 PM, Tim Chown wrote:
On 8 Jun 2011, at 21:19, Keith Moore wrote:
Nor, bluntly, is it about a few big content providers or whomever else you
want to label as important. The internet is a hugely diverse place, and you
don't get to dismiss the concerns of people whom you want to label as red
herrings. Again, 40-something percent of the IPv6 traffic that is observed
on the net today uses 6to4. That's about as much as Teredo, it's a hell of
a lot more than native v6. As long as 6to4 is one of the major ways that
people get IPv6 connectivity (and it clearly is), it's premature to declare
6to4 historic.
You see 40% of your IPv6 traffic as 6to4, we see rather less than 1%. Our
observation point is as a university on an academic/research network that is
native dual-stack. We probably have most of our IPv6 traffic come from other
universities around the world, who are also most likely natively connected.
Hence little if any need for transition methods. This may be different to
your scenario, of course, but it is hopefully a future that will be more
widespread in time.
I'd love it if we all saw a lot more native IPv6 traffic soon.
Just to clarify, the 40% is not from my measurement. It's an approximation to
figures I've seen quoted elsewhere. Like you, I'm sure this figure will vary
from place to place. I haven't tried to do any measurement myself, because the
amount of traffic is not a good indicator of overall usefulness. On the other
hand, if any transit provider anywhere in the world is seeing 40% of v6 traffic
as 6to4, that is a pretty good indication that somebody (besides myself) is
using it.
For that matter, the very fact that operators are observing problems with relay
routers is another indication that people are using 6to4. Why would they be
using it if they didn't want to? I realize that some platforms enable 6to4 by
default, but not all of them do. And I've already said I support having hosts
and routers ship with 6to4 disabled by default.
We did use 6to4 in its router-to-router, site-to-site flavour many years ago
while a project called 6NET ran, but have had no use case for it since.
Perhaps it would be useful to see your use cases more clearly documented with
examples.
I've already given examples. People keep looking for more specific examples in
an argument where any specific example can be dismissed as irrelevant. It's
not any one specific example that matters, it's the fact that people are using
6to4 and there's not an obviously better replacement that's available to them.
The problem is that 6to4 is unfortunately also harmful to real users, at
least the ones that don't want to know about IPv6. It will continue to be
until we can be confident no vendor anywhere has 6to4 on by default, won't it?
NATs are harmful to real users too, and they do a lot more harm than 6to4 does.
When will we deprecate them? When will we declare them Historic?
It's misleading to talk about only the harm being done by 6to4 without
acknowledging the benefits of 6to4 or the lack of a suitable alternative. And
to say that 6to4 does harm is misleading. Is it 6to4 that's doing the harm, or
people who advertise routes to relay routers that don't function properly? Why
are people blaming the 6to4 protocol for configuration errors made by network
operators?
The question is whether Historic stops knowledgeable people like you using
6to4 safely in your own context/community, without affecting 'normal' users.
Does it mean 6to4 off be default, or 6to4 removed from product?
Historic doesn't stop someone who can write his own code. But if it results in
implementations removing support for 6to4, declaring 6to4 as Historic will stop
people who use those implementations.
It's not one versus the other. 6to4 is helping to promote ubiquitous IPv6.
The other view is that 6to4 is delaying ubiquitous IPv6 deployment, by adding
brokenness. Geoff's stats illustrate that very well, though those are not
based on vanilla 6to4.
I disagree with that assessment, because it's only considering the case of
using 6to4 when IPv4 would work just fine. That's not an appropriate metric.
Nobody who has native IPv6 connectivity needs to use 6to4 to reach native
IPv6 destination addresses.
But a deeper problem is the notion that a single set of address selection rules
will work well for all, or even most, applications.
Keith
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