On Mon, 29 Nov 1999 08:47:16 PST, "Fleischman, Eric W" said:
> 3) Given the current situation of corporations using private
> addresses internally and a smaller set of global IPv4 addresses on
> their periphery, and a global IPv4 internet, one should theoretically
> be able to say how many public IPv4 addresses have been assigned and
> therefore how many remain unassigned and by so doing estimate how long
> until consumption. Why is this not possible in practice?
Well, because it's a moving target.
If it takes 3 weeks to get the data together, and your growth
rate is high enough that there's a measurable change over 3 weeks,
you then have to apply a correction factor to your estimate.
Given that you don't know the growth rate exactly, this gets
more than a tad interesting....
I seem to remember the ZEALOT(?) project, which at one time posted
an estimate of the DNS size every 3 months, and one of the last
postings mentioned that it was taking well over a week to do
the survey. And that was a while ago.
Added in to that is the difficulty in computing how many IPv4
addresses are actually assigned - you can get a *vast* over-estimate
by counting up the CIDR blocks visible to the core routers.
However, in the case of Virginia Tech, you'll see the 128.173/16
and 198.82/16 netblocks advertised - but we're nowhere near 128K
addresses actually allocated (I think the actual number is closer
to 20K or so).
Most of the router gurus I've talked to don't think the actual
number of addresses is an issue - the issue is allocating them
such that a "small enough" number of CIDR aggregations covers them
(as 30K poorly allocated IPv4 addresses and 300M well-allocated will
both take 30K routing table entries...)
Valdis Kletnieks
Operating Systems Analyst
Virginia Tech
