Test your connectivity for World IPv6 Day

Tassos Chatzithomaoglou achatz at forthnet.gr
Wed Jun 1 20:11:21 CEST 2011

Stefan Neufeind wrote on 01/06/2011 19:32:
> On 06/01/2011 06:28 PM, Guillaume.Leclanche at swisscom.com wrote:
>>> The reason Chromium was "working" fine is because it was using IPv4 in
>>> order to connect to the dual-stack sites included in eyechart. As
>>> someone else pointed before, it would be good to have IPv4/IPv6
>>> differentiation shown.
>>> For everyone interested, from http://codereview.chromium.org/7029049
>>> When a hostname has both IPv6 and IPv4 addresses, and the IPv6 address
>>> is listed first, we start a timer (300ms) (deliberately chosen to be
>>> different from the backup connect job). If the timer fires, that means
>>> the IPv6 connect() hasn't completed yet, and we start a second socket
>>> connect() where we give it the same AddressList, except we move all
>>> IPv6
>>> addresses that are in front of the first IPv4 address to the end. That
>>> way, we will use the first IPv4 address. We will race these two
>>> connect()s and pass the first one to complete to
>>> ConnectJob::set_socket().
>> Doesn't this sound like an implementation of Happy Eyeballs (http://tools.ietf.org/html/draft-ietf-v6ops-happy-eyeballs-02) ?
> Hi,
> not fully according to the spec as this post says:
> http://www.ietf.org/mail-archive/web/v6ops/current/msg09017.html
> but close. I guess the basic idea is similar ...
> Kind regards,
>   Stefan Neufeind

What is interesting is that it started as a temporary hack for IPv6 
world day (like Microsoft did recently in 
http://support.microsoft.com/kb/2533454), probably it didn't work as 
expected, so the fallback mechanism (happy-eyeballs-like) was chosen 


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