Jason Fesler jfesler at gigo.com
Thu Jan 27 18:52:51 CST 2011

> Note you can have totally broken IPv6 connectivity and still be
> fine on World IPv6 day.  You just need applications with good
> multi-homing support.

Agreed so far.

> No web site can check this for you.

Hmm. What's wrong with asking the browser to try a dual-stack url today, 
as a proxy for what will happen to said web browser on June 8?

The concern with World IPv6 day is with the users who have IPv6 enable, 
and have a default route - yet have broken IPv6 connectivity.  This 
specific population will see timeouts on June 8.

> If you are a application developer and want TCP example code that
> will work well with a broken IPv6 connection have a look at my blog.

Hopefully browsers will adopt your idea (or Happy Eyeballs).
It may be the only remedy available, short of content providers
collectively moving forward with dual stack, 0.05% broken users be damned.


I'm personally not a big fan of either method, as that's going to increase 
the amount of tcp sessions to my web servers.  It is merely less bad than 
the alternative.

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