[address-policy-wg] 2007-05 New Policy Proposal (IPv6 ULA-Central)
Wilfried Woeber, UniVie/ACOnet Woeber at CC.UniVie.ac.at
Fri May 4 15:08:21 CEST 2007
Geoff Huston wrote: > 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. That formula does apply under the assumption(s) that the draws will be evenly distributed across the value space, correct? > http://draft-huston-ipv6-local-use-comments.potaroo.net > > Geoff > Wilfried.