2000::/6

Jimmy Hess mysidia at gmail.com
Sun Sep 14 21:19:42 UTC 2014


On Sat, Sep 13, 2014 at 5:33 AM, Tarko Tikan <tarko at lanparty.ee> wrote:
> 2000::/64 has nothing to do with it.
>
> Any address between 2000:0000:0000:0000:0000:0000:0000:0000 and
> 23ff:ffff:ffff:ffff:ffff:ffff:ffff:ffff together with misconfigured prefix
> length (6 instead 64) becomes 2000::/6 prefix.

It should be rejected for the same reason that  192.168.10.0/16 is
invalid in a prefix list  or access list.

Any decent router won't allow you to enter just anything in that range
into the export rules  with a /6,  except 2000::  itself, and will
even show you a failure response instead of silently ignoring the
invalid input,  for the very purpose of helping you avoid such errors.
   2001::1/6  would be an example of an invalid input --  there are
one or more non-zero bits listed outside the prefix, or where  bits in
the mask are zero.

Only 2000:0000:0000:0000:0000:0000:0000:0000/6    properly conforms,
not just "any IP"   in that range  can have a /6  appended to the end.


-- 
-JH


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