North American Network Operators Group

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Re: who gets a /32 [Re: IPV6 renumbering painless?]

  • From: Stephen Sprunk
  • Date: Sun Nov 21 15:20:11 2004

Somebody said:
>if the ipv6 routing table ever gets as large as the ipv4 routing table >is
>today (late 2004 if you're going to quote me later), we'll be in deep >doo.

*WHEN* the ipv6 routing table gets as large as the ipv4 routing table
is today (late 2004, when you quote me later) it won't be a problem.
Agreed. When the IPv6 table has as many routes as today's IPv4 table, we'll need four times the storage; Moore's Law says, as long as that doesn't happen within 36 months, it's not a problem. I haven't seen anyone (recently) predict IPv6 adoption will be anywhere near that fast, much less faster.

Thus spake "Paul Vixie" <>
but it's not just the routers, it's churn.  "it's always noon somewhere."
the stability of the distributed system called "the global routing table"
is directly proportional to its size.  the number of participants in that
system, each of whom must build their own model of the system using only
the messages they get from direct neighbors, cannot usefully exceed *some*
maximum for any given total number of discrete destinations.
first, the current distance-vector approach used by BGP just
won't scale to O(1e12),
Probably not, even if router vendors start using reasonably modern processors.

and second, i don't think that you think that there are enough participants
who want to own routers to make such a table size necessary.
As a point of reference, today in IPv4 there are 16k origin-only ASes. Assuming reasonably sane RIR policies, we can expect -- even with the issue of one PI prefix per AS -- that there would be 16k end-site PI routes today, with linear growth similar to the current allocation rate of ASNs. This is not even remotely a problem until well after we have to switch to 32-bit ASNs; in fact, the situation will be far better than what we will likely have with IPv4 at that point.

mr. doran argued for many years that routing table slots should be
auctioned or leased.  i never did and still do not agree with him, but his
starting assumptions weren't and aren't my point of disagreement.
The idea has obvious appeal, but it seems like a clear case of the cure being worse than the illness once you consider the logistical and technical requirements.


Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking