using "reserved" IPv6 space

valdis.kletnieks at vt.edu valdis.kletnieks at vt.edu
Thu Jul 19 18:29:14 UTC 2012


On Wed, 18 Jul 2012 21:07:35 +0300, Saku Ytti said:

> If collision occurs, if dispute occurs, provability that one party did not
> use BCP method can be useful to solve dispute and decide who renumbers.

Looking at actual numbers out of RFC4193:

   The following table shows the probability of a collision for a range
   of connections using a 40-bit Global ID field.

      Connections      Probability of Collision

          2                1.81*10^-12
         10                4.54*10^-11
        100                4.54*10^-09
       1000                4.54*10^-07
      10000                4.54*10^-05

OK?  So even if you merge and re-merge, and go on a massive buying spree and
accumulate a network where you have to interoperate 1,000 ULAs, you're *still*
looking at a literally million-to-one shot.  And if you only have a mess of 100 ULAs,
it's a billion-to-one.

Now, compare that to the chances that you'll acquire 2 companies, both of whom
had an employee who didn't actually generate a proper random number, but did
this sort of thing instead:

http://www.spinics.net/lists/linux-driver-devel/msg26431.html

A lot of people are worrying about the wrong problem.


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