estimation of number of DFZ IPv4 routes at peak in the future

George Herbert george.herbert at
Tue Mar 8 22:55:57 CST 2011

On Tue, Mar 8, 2011 at 8:40 PM, Owen DeLong <owen at> wrote:
> You have ignored the probability of disaggregation due to IP trading markets, especially
> given the wild-west nature of the APNIC transfer policy.
> Many of the legacy blocks will get dramatically disaggregated in the likely market which
> could take the DFZ well beyond 500k routes.
> It will be very interesting to watch.
> Owen
> On Mar 8, 2011, at 7:17 PM, Mikael Abrahamsson wrote:
>> Hi.
>> We had an interesting discussion the other day at work. We were speculating on how many DFZ IPv4 routes there would be at peak in the future before it starts to decline again due to less IPv4 usage. The current number is around 350k, and my personal estimation is that it would grow by at least 100k more due to the the last 5 /8s being carved up at around /22 meaning each /8 ending up with 16k routes, plus the last allocations being seen in the remaining RIR "normal allocations" would be smaller than before plus de-aggregation of space as people "sell" or "lease" subspace of their allocations.
>> My guess therefore is a peak around 450-500k IPv4 DFZ routes and that this would happen in around 3-5 years. I wanted to record this for posterity.
>> What is your guess, any why?

Strange, had this exact conversation with a boutique ISP owner I know
earlier today...

My hope is that things peak around 510k and that routers that can
handle about a million routes now can handle all of IPv4Peak and IPv6
growth for their economic lifetimes.

Disaggregation and leasing of space (or whatever) could easily spike
that significantly, but aren't likely to further increase the rate of
new announcements, merely how long we keep going with them.

I predict that we can't really predict this yet; IPv6 actual adoption
isn't far enough along to tell how bad that will end up being.

If it's five years before it dominates things, we're screwed on IPv4
tables.  People who need smallish but routeable blocks will be able to
find them and pry them loose via enough funds and announce them.  5
more years of that, and current routers go "poof".  Many go "poof"

-george william herbert
george.herbert at

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