Moving to IPv6

Lennart Sorensen lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org
Wed Sep 8 22:01:04 UTC 2010


On Wed, Sep 08, 2010 at 05:31:59PM -0400, sciguy-Lmt0BfyYGMw at public.gmane.org wrote:
> Wikipedia also says there will be address exhaustion in a year. Forgive me
> if I'm wrong, but it seems the way that in the proposed IPv6, the way the
> address space will be allocated will make it possible for IPv4 to still
> work. An IPv4 address of A.B.C.D will be equal to an IPv6 address of
> A.B.C.D.0.0.0.0, for instance. Would a router have a problem with the
> trailing zeroes (the correct behaviour appears to be to toss them out)?
> The last four groups of hex digits make it possible to add more hierarchy
> to networks, making for a more finely-tuned management of the network.
> 
> That may explain why there is not much of a panic, despite an agreed upon
> exhaustion of numbers by 2011. All that might really happen is your ISP
> will assign an IPv6 number, and your router will just ignore the last 4
> sequences (which are probably just zeroes anyway), if all it knows is
> IPv4.
> 
> Just wondering out loud. Not sure if any of this makes sense.

No it doesn't.

IPv4 is 32bit.  IPv6 is 128bit.  If you used IPv4 style notation for
IPv6 you would get x.x.x.x.x.x.x.x.x.x.x.x.x.x.x.x

So you would have to add 12 zeroes to an IPv4 address to make it the
right size.  That however doesn't match with how IPv6 addresses are
supposed to get allocated as far as I know.

I have seen tunnels use FE:80::(IPv4 address) as the local address.
That is, 192.168.1.1 would be FE80:0:0:0:0:0:C0A8:101 if used as a base
for the link local address.

-- 
Len Sorensen
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