nanog mailing list archives

Re: [Re: http://tools.ietf.org/search/draft-hain-ipv6-ulac-01]


From: Christopher Morrow <morrowc.lists () gmail com>
Date: Thu, 22 Apr 2010 01:51:51 -0400

On Wed, Apr 21, 2010 at 9:35 PM,  <Valdis.Kletnieks () vt edu> wrote:
On Thu, 22 Apr 2010 07:30:51 +0930, Mark Smith said:

"  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

   Based on this analysis, the uniqueness of locally generated Global
   IDs is adequate for sites planning a small to moderate amount of
   inter-site communication using locally generated Global IDs."

There is a measured rate by RIRs and the like on the order of 10^-6 for
accidentally issuing duplicate integers (roughly approximated by 2 cases of
duplicate ASNs out of (300K routes + 30K ASNs).  In other words, unless you
have over 1,000 or so backdoor links, you're more likely to get screwed over by
an administrative drone fscking up your paperwork than you are of a statistical
collision.

it's not about the frequency of collision, it's about the cost to
rectify one/two/some.

and the complexity this adds to every host/router/device in/around the
network (dns, firewalls, acls, etc... icky)

-chris


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