[manet] Re: BABEL question

I believe that, due to the so called "Birthday Paradox", If you select
2**32 (about 4.2 billion) values from a pool of 2**64 values with
replacement, the probability of a conflict among the selected values
50%. https://en.wikipedia.org/wiki/Birthday_problem The thing is that
to determine whether there is a conflict, you need to compare all
unordered pairs. With N items, the number of pairs is N*(N-1)/2 so the
number of cases of possible conflict goes up with the square. The
number of unordered pairs of 2**32 things is ~2**63.

Thanks,
Donald
===============================
 Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
 2386 Panoramic Circle, Apopka, FL 32703 USA
 [email protected]

On Thu, Jul 24, 2025 at 5:51 PM Juliusz Chroboczek <[email protected]> wrote:
>
> > Imagine a prefix like: "2001:db8:f000::/48" where the lower 16 bits of
> > the /64 do not represent a subnet ID but instead identify a host route
> > delegation service.
>
> I most respectfully disagree.
>
> I have no objection to defining a flat prefix of MANET interface
> addresses.  However, the prefix must be flat, as anything else is
> gratuitious complexity that doesn't bring any practical benefits.
>
> (Henning is right, by the way, a /64 is good enough.  If I recall my
> undergrad combinatorics correctly, a /64 gives a vanishingly small
> probability of collision when the total number of nodes is less than
> 4.2 billion.  For a /48, the value is roughly 10¹².)
>
> -- Juliusz
>
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