On 5/4/07, Gert Doering <gert@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