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

Sun Nov 21 17:10:50 UTC 2004

> >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.
> 
> As a matter of fact, I would bet that Cisco , Juniper, and any other 
> edge/core router manufacturer are banking on this happening.

if it were just the routers, then you're apparently expecting the same
owners to need better ones, and i agree that a router vendor would probably
look very favourably on such a development.  however, i'm counting on new
owners needing their first routers, and an O(1e6) sized routing table doesn't
make any difference there -- a router vendor might be even happier, in fact.

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.  if you think
that the number of available participants leads to a maximum stable table
containing O(1e6) destinations, then you should be arguing for a /20
minimum allocation size.  If you think the table in question has O(1e10)
destinations then you'd be arguing for a /30 minimum allocation size.  But
to consider a /40 minimum allocation size, you'd be saying that you thought
a table containing O(1e12) discrete destinations, and i think that's false
in two ways -- first, the current distance-vector approach used by BGP just
won't scale to O(1e12), 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.

someone asked about my "sole benefit" comment, so i'll amend it.  it's not
a global cost and sole benefit, but it is a global cost to the "other ends"
with the preponderance of benefit (for a prefix) falling on the owner of
the prefix.  so it's not one-sided but it is certainly an assymetric
benefit with a symmetric cost.  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.
-- 
Paul Vixie