[190012] in North American Network Operators' Group
Re: Netflix banning HE tunnels
daemon@ATHENA.MIT.EDU (Baldur Norddahl)
Mon Jun 13 08:43:15 2016
X-Original-To: nanog@nanog.org
To: nanog@nanog.org
From: Baldur Norddahl <baldur.norddahl@gmail.com>
Date: Mon, 13 Jun 2016 14:43:08 +0200
In-Reply-To: <A6ED8338-AEC2-4481-BF78-E79B9F9EB6DB@delong.com>
Errors-To: nanog-bounces@nanog.org
On 2016-06-13 11:22, Owen DeLong wrote:
> Fine… Consider 2001:0:0:406:0:0:5:302. Owen
That is a Teredo reserved address. Neither option makes any sense
because it is an invalid Teredo address. You can find examples with two
equal possible :: blocks but they are actually rare. Try to find one
that has non zeros in the first 32 bits, as that is usually the case for
any actually assigned prefix. I hold that for any actually assigned
prefix, it will almost always be the first possible :: block that makes
sense - prove me wrong.
Consider:
2001:db8:1:2:3:4:5:6
Provided that the first two 16 bit blocks are non zero, there can only
be multiple equal runs of zeros if the run length is 2. This follows
from the rule that disallows shorting out a single :0:.
Now this leaves the following:
2001:db8:0:0:1:1:0:0 => 2001:db8::1:1:0:0 is most sane because this
would usually be host 1:1:0:0 in prefix 2001:db8::/64.
2001:db8:0:0:1:0:0:1 => 2001:db8::1:0:0:1 for the same reason.
2001:db8:1:0:0:1:0:0 => 2001:db8:1::1:0:0 because this is host 1:0:0 in
the prefix 2001:db8:1::/64
And that was all possible ways you can have multiple :: blocks in an
actually assigned prefix.
Regards,
Baldur
