Yahoo and IPv6

Scott Helms khelms at
Mon May 9 16:38:43 UTC 2011

I believe the problem Yahoo is talking about in regards to "broken" IPv6 
networks.  It really comes down to your network would break for 0.078% 
of the people trying to reach their site via IPv6.  Broken in this case 

...."the user has a broken home gateway, or a broken firewall or his Web 
browser has a timeout that's between 21 and 186 seconds, which we 
consider to be broken. That's a lot of breakage, and that is a very big 
barrier for content providers to support IPv6."

On 5/9/2011 12:25 PM, Valdis.Kletnieks at wrote:
> On Mon, 09 May 2011 18:16:20 +0300, Arie Vayner said:
>> Actually, I have just noticed a slightly more disturbing thing on the Yahoo
>> IPv6 help page...
>> I have IPv6 connectivity through a HE tunnel, and I can reach IPv6 services
>> (the only issue is that my ISP's DNS is not IPv6 enabled), but I tried to
>> run the "Start IPv6 Test" tool at and
>> it says:
>> "We detected an issue with your IPv6 configuration. On World IPv6 Day, you
>> will have issues reaching Yahoo!, as well as your other favorite web sites.
> The *really* depressing part is that it says the same thing for me, on a *known*
> working IPv6 network.
> And then when I retry it a few minutes later, with a tcpdump running, it works.
> And then another try says it failed, though tcpdump shows it seems to work.
> For what it's worth, the attempted download  file is:
> % wget
> --2011-05-09 11:44:39--
> Resolving 2001:4998:f00d:1fe::2000, 2001:4998:f00d:1fe::2002, 2001:4998:f00d:1fe::2003, ...
> Connecting to|2001:4998:f00d:1fe::2000|:80... connected.
> HTTP request sent, awaiting response... 200 OK
> Length: unspecified [image/png]
> Saving to: `eye-test.png.1'
>      [<=>                                    ] 2,086       --.-K/s   in 0s
> 2011-05-09 11:44:39 (154 MB/s) - `eye-test.png.1' saved [2086]
> Looking at the Javascript that drives the test, it appears the *real* problem
> is that they set a 3 second timeout on the download - which basically means
> that if you have to retransmit either the DNS query or the TCP SYN, you're
> dead as far as the test is concerned.

Scott Helms
Vice President of Technology
ISP Alliance, Inc. DBA ZCorum
(678) 507-5000

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