@kasperd

That's the question.

W.B. was opening my eyes.

I have seen the
::c0:0:100:0
::c0:0:200:0
but I thought it is a kind of leet speak for clat, but it is 192.0.0.1 192.0.0.2 and so on.

So I don't know what happens with 8 or 9 devices, since 192.0.0.0 is already the virtual default gw.

I see. Those are following the /64 mappings in RFC 6052. This is not exactly the purpose that RFC 6052 is intended for. And you already identified the scalability challenges of that approach.

I am guessing they use duplicate-address-detection to ensure two machines don’t pick the same address. if that guess is correct you can easily verify what happens. Just make have a machine use all of the addresses ending in c0:0:0:0 ti c0:0:700:0 before the test machine connects to the network.

If the implementation is even just a little bit sensible it will see that its preferred IPv6 addresses are already in use and pick a random IPv6 address instead. It can still use any address in the 192.0.0.0/29 range locally.

@kasperd

DAD works, but nothing more.

Or in other words: At the moment it is not possible to use more than one Windows-PC with IPv6-mostly-support (Preview only ) in a IPv6-mostly or IPv6-only Network.

By accident a host may use one of the other mapped IPv4 addresses (out of 192.0.0.0/29) . But in general it takes the first one anywhere.

and W.B. is right: MS has to fix that problem before it gets released for the masses

#ipv6mostly #ipv6only #ipv6 #clat #windowspreview

@tschaefer @kasperd

Wait, so:
They're assigning an additional v6 address to the CLAT, but then they're encoding the CLAT v4 address (in 192.0.0.0/29) into that v6 address for some reason? E.g. the 2001:a61:4b7:63ec:c0:0:100:0(Bevorzugt) address in the screenshot?

Like, why???

The whole point functioning there is, afaik, that the CLAT v4 address is supposed to be locally significant only, and therefore the actual size of the v4 CLAT address range is irrelevant. Why would they intentionally do something to make this locally-significant address into something significant to the whole network?