From the dualstack-is-fun department...

Cameron Byrne cb.list6 at
Tue Mar 1 16:49:46 CET 2011

On Tue, Mar 1, 2011 at 4:29 AM, Andrew Yourtchenko <ayourtch at> wrote:
> On Tue, Mar 1, 2011 at 8:31 AM, Cameron Byrne <cb.list6 at> wrote:
>> On Feb 28, 2011 10:41 PM, "Andrew Yourtchenko" <ayourtch at> wrote:
>>> Daniel,
>>> On Tue, Mar 1, 2011 at 1:34 AM, Daniel Roesen <dr at> wrote:
>>> > On Tue, Mar 01, 2011 at 12:07:36AM +0000, Bjoern A. Zeeb wrote:
>>> >> And, would you have noticed the IPv6 related bug if happy-eyeballs was
>>> >> already implemented or would legacy IP have worked well enough for you
>>> >> to not notice (read as - what's better?, getting the bug fixed or not
>>> >> noticing and harming IPv6 for longer)?
>>> >
>>> > IPv6 is not customer-driven, but provider driven. So #1 priority must be
>>> > that "things keep working" as painless as possible.
>>> >
>>> > But you're right in the sense that with Happy Eyeballs we need methods
>>> > to measure problems being masked by HE. How, is one of the things
>>> > which seem to be missing in the Happy Eyeballs discussion.
>>> Totally agree. Like I told to Bjoern when we met in @fosdem a few
>>> weeks ago - from the pure engineering point of view I think a good
>>> thing that could happen is IPv4 would suddenly vanish from the face of
>>> earth for 3-4 months. Then we notice all the problems and can fix them
>>> (very fast ;-) (Un)fortunately this is not possible - as it would be a
>>> major catastrophy from the user experience point of view.
>>> Happy Eyeballs is a bit on the other side of the spectrum - by working
>>> hard to make the UX as seamless as possible indeed it masks these
>>> kinds of problems - so with it the chances are high that these
>>> problems will not be noticed. Actually, even more so since the
>>> opportunistic connection establishment that you mentioned in the first
>>> mail might not even happy if the single protocol consistently wins (so
>>> it is not 100% true about the increase in load).
>>> We plan a bar bof @Prague, I will definitely bring this topic up there
>>> too - meantime if you have ideas, feel free to write them up for the
>>> discussion.
>>> Side remark: I noticed this trend overall - the more robust you have a
>>> protocol to external influences (soft failures instead of hard
>>> failures), the "nicer" is the user experience, and the more hell is in
>>> debugging of this protocol for the support/dev folks when the
>>> experience slowly degrades to the point of being unacceptable. It's a
>>> tough choice.
>> This also creates the ugly situation where customer calls help desk saying
>> website x is down, support person tries to get to website x, and it works.
>> Help desk says, nope "works for me" and the broken ipv6 access or dare I say
>> ipv4 access is broken to the none-HE user but works for the HE user. If the
>> none he-user cannot easily convince others that there is a problem, that is
>> bad.
> Yes, we already have in the latest text:
> "Debugging and Troubleshooting
> This mechanism is aimed to help the user experience in case of connectivity
> problems. However, this precise reason also makes it tougher to use these
> applications as a means of the verification that the problems are fixed. To
> assist in that regard, the applications implementing the proposal in this
> document SHOULD also provide a mechanism to temporarily use only one
> address family."
> Too weak ? Wrong approach ?

I don't there is anything that you could write in an IETF draft that
would make joe-six-pack understand or care about HE.

>> This is a support nightmare as HE masks the issue and will not be uniformly
>> deployed -- ever.
>> This is a classic dilemma. Masking the problem ostensibly makes it go away,
>> but at the same time exacerbates the ability to resolve it. It is kind of
>> like beer :)
>> and beer is good, especially when I been troubleshooting
>> connectivity issues all day and my customers keeping telling me  websites
>> are down
>> ... but not all of them ... they all but works for me ....
> ...and "no-one changed anything". (That's what everyone says for the

Most browsers i have update themselves, or windows update, or apt-get
update them and i generally don't care to know what the updating is
that happened... updates are good in my world.  In some larger
corporate environments i know, IE6 is mandatory.

> past 15 or so years, I keep asking just in case, to see how often it's
> "we changed X and Y has broken". I can count the occasions on fingers
> of one hand, vs. the ~mid-4-digits number of the other outcome. So
> fundamentally nothing changes - it breaks by itself today too :-)

Yep.  And software updates are just like that.  They happen by
themselves, literally.

> (but seriously: appreciate all of the comments. I thought the above
> blurb about troubleshooting in the draft should be enough, but maybe
> it is not too strongly worded.

When was the last time your read a warning label on a beer bottle?

> Maybe there needs to be some way to flag the problem that has been
> worked around. To whom ? How ? Is it supposed to be specifit to this
> area or maybe should there be something generic ? I think I'm getting
> on hyperbolic HE-tangent trajectory with these questions.)


> cheers,
> andrew
>> Cb
>>> cheers,
>>> andrew

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