Yesterday's Windows update causes IPv4 to be default

[Dan Wing]

> -----Original Message-----
> From: ipv6-ops-bounces+dwing=cisco.com at lists.cluenet.de [mailto:ipv6-
> ops-bounces+dwing=cisco.com at lists.cluenet.de] On Behalf Of Tassos
> Chatzithomaoglou
> Sent: Wednesday, November 14, 2012 9:00 AM
> To: ipv6-ops at lists.cluenet.de
> Subject: Re: Yesterday's Windows update causes IPv4 to be default
> 
> http://support.microsoft.com/kb/2750841
> 
> /Assume that a computer is configured to use an IPv6 connection as the
> default connection.
> Additionally, assume that the computer does not have a connection to an
> IPv6 network. In this situation, it takes a long time for the computer
> to connect to an IPv6 site. // // //This issue occurs because Windows
> tries the IPv6 connection first. After the connection fails because of a
> time-out error, Windows tries the IPv4 connection.// // //After this
> update is installed, Windows uses the NCSI functionality to examine the
> Ipv6 connection. If the connection is broken, Windows uses IPv4 instead
> of IPv6./

Yep, Windows 8 has been doing that since Windows 8 shipped.  Full
details are in my Cisco Live slide deck (I'll have to find a pointer)
and a pretty good summary is 
http://blogs.msdn.com/b/b8/archive/2012/06/05/connecting-with-ipv6-in-windows-8.aspx

-d


> --
> Tassos
> 
> Dick Visser wrote on 14/11/2012 18:46:
> > Hi
> >
> > I looks like yesterday's batch of updates causes Windows 7 to prefer
> > IPv4 over IPv6.
> > After (automatically) installing the whole lot, one of my users
> > complained about connection issues with WinSCP to our web server.
> > This runs SSH on IPv6-only. His WinSCP for some reason tried to
> > connect over IPv4, without falling back to IPv6.
> > I tried "ping www.terena.org" and that also used IPv4.
> > "ping -6 www.terena.org" did also work, but I'm pretty sure it used to
> > default to IPv6.
> > After clearing the cache in WinSCP things started to work again.
> >
> > I didn't install the updates (about 20, including the Office ones) on
> > my own computer, so I had a look at them first.
> > One of them is called "No network connectivity on Windows 7-based or
> > Windows Server 2008 R2-based client computers when a DHCPv6 message is
> > sent that has a duplicated DUID",
> > http://support.microsoft.com/kb/2763523, which is the only one that
> > mentions IPv6.
> >
> > Before installing anything, I tried to "ping www.terena.org" and that
> > used IPv6 all-right.
> > I then installed all the updates except the suspicious
> > http://support.microsoft.com/kb/2763523.
> > After rebooting, "ping www.terena.org" uses IPv4...
> >
> > So I guess one of the other updates caused this; I'm now booting up a
> > VM to investigate which one exactly.
> > So far the no other major stuff broke, and it looks like only the
> > default has changed, but I'd thought I mentioned it here anyway, just
> > in case...
> >
> > Anyone else has seen IPv6 issues on Windows since yesterday?
> >
> >
> >