below... Chirayu Patel wrote: > > > The usage that is actually envisaged is more limited: an identifier that > > provides disambiguation in a limited environment, normally a single > > site, possibly a small number of sites directly linked by VPN-like > > relations. In that scenario, the collisions that matter are those that > > occur within this "working set" of connected sites. The probability of > > such a collision is determined by the probability of collision "x" > > between two identifiers (x = 2^-40 in our example) and by the size "W" > > of the working set. The probability that single site does not collide > > with any member of a working set is: > > > > P(collision in a set of size W) = 1 - (1-x)^(W-1) > > Seems incorrect. > > Assuming that the pool size is "n", where n = 2^40. > > As per your formula the probability of choosing two unique numbers is (n-1)/n, > and of three unique numbers is ((n-1)/n)*((n-1)/n). > > As per Geoff, the probability of choosing two unique numbers is (n-1)/n, and > of three unique numbers is ((n-1)/n)*((n-2)/n). > > Since the space from which you can choose a unique number diminishes by one > with each draw. I think Geoff's formula is correct in this regards.
No. The space does not diminish at all in the local assignment method, since every draw is totally independent of every other draw. The space diminishes by one in the central assignment method, but it doesn't matter since collisions are excluded by construct in that case. Brian -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
