[address-policy-wg] 2007-05 New Policy Proposal (IPv6 ULA-Central)

On 5/4/07, Gert Doering <gert at space.net> wrote:
>
> Hi,
>
> On Fri, May 04, 2007 at 11:54:22AM +0200, Shane Kerr wrote:
> > The motivation for a version with a central registry however is not so
> > obvious to me. The only justification I can think of is that you can
> > be sure not to pick the same /48 as someone else has picked. But the
> > chances of that are *billions* (that's "thousands of millions" to
> > British folk) to one!
>
> Take the "birthday paradoxon" into account.  Chances for a clash with
> "someone else in the room" are actually much higher than the chance
> for a clash with "a *specific* number out of the ame pool".


   The general solution of
   the probability of a collision after d draws from n possible values
   is given by:

      P = 1 - ((n!) / ((n**d)((n-d)!)))

   Given that the value for n is 2.199,023,255,552, then the objective
   is to find the lowest value of d for which P is greater than or equal
   to 0.5. In this case the value for d  is some 1.24 million.


http://draft-huston-ipv6-local-use-comments.potaroo.net

  Geoff
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