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

Sun Nov 21 19:57:08 UTC 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" <vixie at vix.com>
> 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.

S

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 