Windows 7 IPv6 fail

Martin Millnert martin at
Fri Oct 29 12:00:26 CEST 2010

Squirrelmail ate up my attached file.  Here it is. ( I hope :))

On Fri, October 29, 2010 11:38 am, Martin Millnert wrote:
> Hi list,
> I'm running Windows 7 on my home box dual-booted, so I had the luck to
> find a quite severe error (IMHO) in its IPv6 stack today:
>    When (all?) IPv6 addresses on its wired interface becomes deprecated
> for whatever reason, it will still send out packets to the (wired)
> on-link router with Teredo source address.  (uhm, yeah, we were missing
> BCP38-style filters on the v6 router)
> My Windows 7 network configuration is entirely vanilla, everything
> automatic from the network.
> For a better description on what I found, please see the attached
> text-file.
> So this is incorrect behaviour, for various reasons. In my case, our v6
> resolvers that we hand out via stateless DHCPv6 (resolvers only), are
> being used for domain name look-up with a Teredo source address.
> Reasonably, this is unsuccessful, since the source address isn't within
> the ISP allocated space, and the resolvers won't answer that.
> Most web browsing worked fine, since there are 3 IPv4 resolvers to
> fall-back to.  But I stumbled on one name which the system failed entirely
> to look-up: I'm not sure how this came about; the v4 resolvers
> would answer this name, yet the system wouldn't give me an answer.
> ping/browsing to failed.
> A myriad of things could be 'fixed' / looked in to, IMO. For example:
>  - Why query resolvers configured on the wired interface using an address
> configured on another interface?
>  - Why send packets on the wired interface with a source address taken
> from another interface, in this case Teredo?
>  - Why keep/use the v6 resolvers on the wired interface when addresses
> becomes deprecated, and wired IPv6 essentially drops? At least when
> resolvers aren't using link-local addresses?
> MS clue greatly appreciated.
> Cheers,
> --
> Martin Millnert <martin at>

Martin Millnert <martin at>
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