Hi Geoff,
I was also surprised by this number [46%] when I first saw it in the output.
Your number is higher, but the analysis I did also showed HD ratio could have a significant impact on the address space consumption. (http://www.ripe.net/ripe/policies/proposals/comments/impact_of_hd.html posted on this list some weeks ago) Looking at all invidual allocations done by RIPE NCC between 2003 and 2006, we modelled the observed growth to a policy which used HDR 0.96 instead of 80% utilisation as the criterium for an LIR to be eligible to receive an additional allocation. Starting 1/1/2003 and stepping through time the simulation thus determined the address space held by each LIR on a day by day basis. By 1/1/2006 this resulted in some 60 million (about 30% of the total) more addresses allocated compared to what we actually had handed out under the 80% rule. Reading your report, I believe one of the reasons our numbers differ is that you are simulating 10,000 allocations; my analysis only looked at the 5,121 allocations done by RIPE NCC in 2003-2006. Since the effects of HD ratio are progressive, the more allocations you simulate, the higher the relative increase in address space consumption becomes.
This experiment has been repeated 1,000 times in order to determine a stable average value for the relative increase in address consumption corresponding to a change in the address allocation policies from uniform 80% to an HD Ratio of 0.96, assuming constant demand for addresses.
To get a feeling of how stable your average is, could you indicate what the variation, the standard deviation in these 1,000 repeats is? i.e. did all 1000 give you a number close to 46% or were they spread out a lot?
A related consideration is that of the adoption of such a policy proposal by all 5 RIRs.
From http://www.arin.net/policy/proposals/proposal_archive.html I understand ARIN already abandoned two proposals to use HD ratio for IPv4 allocations (nrs. 2004-2 and 2003-10).
Regards, -- Rene =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Rene Wilhelm RIPE Network Coordination Centre Email: wilhelm@ripe.net Amsterdam, the Netherlands Phone: +31 20 535 4417 Fax: +31 20 535 4445 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=