Re: [address-policy-wg] 2005-01 - Last Call for Comments (HD-ratio Proposal)

[Geoff Huston gih@localhost]

At 04:00 AM 23/02/2006, Randy Bush wrote:
> > I trust that this report is helpful in terms of assessing some of the
> > impacts of the proposal.
> >
> > ...
> >
> > From the simulations of registry allocations, the use of an HD Ratio of
> > 0.96 for IPv4 address allocations made by the RIPE NCC is predicted to
> > increase total address consumption by 46% over the existing flat 80%
> > utilization allocation policy framework.
>
> YIKES!!!!
>
> and, aside from that, how was the play, mrs. lincoln?
I was also surprised by this number when I first saw it in the output.

Looking behind this 46% number, the outcome is a result of the amplified 
effects of the HD Ratio for large allocations. 50% of this increased 
address consumption is in allocations of /9 and /10 prefixes, which only 
account for 1% of all actual allocations, but 20% of the allocated addresses.
The other effect is a shift from /16 to /15 allocations in this HDR regime 
- /16s and /15s together contribute a further 15% to this increased address 
consumption.
Here's the table that shows the shifts when using the HD Ratio

(fixed width font will help here)

Prefix  RIPE NCC        Equivalent
        Allocations     Allocations
        2000-2006       0.96 HD
        (Relative %)    (Relative %)

/24     23.04   23.23
/23     12.09   11.37
/22     8.16    7.87
/21     4.76    4.85
/20     19.64   16.33
/19     14.97   15.21
/18     6.85    8.58
/17     3.56    4.39
/16     4.36    3.88
/15     1.18    2.39
/14     0.66    0.86
/13     0.38    0.5
/12     0.18    0.28
/11     0.13    0.15
/10     0.03    0.09
/9      0       0.02
/8      0       0

Power of        Address Address 
Difference      Relative                Relative        Relative
2       Span    Span            Difference              Address Address
        Actual  HDR                             Span    Span
                                                Actual  HDR
8       5898    5947    49      0%              0%      0%
9       6190    5821    -369    0%              0%      0%
10      8356    8059    -297    0%              0%      0%
11      9748    9933    184     0%              1%      0%
12      80445   66888   -13558  -2%             4%      2%
13      122634  124600  1966    0%              7%      5%
14      112230  140575  28344   3%              6%      5%
15      116654  143852  27197   3%              6%      5%
16      285737  254280  -31457  -4%             15%     9%
17      154665  313262  158597  19%             8%      12%
18      173015  225444  52429   6%              9%      8%
19      199229  262144  62915   7%              11%     10%
20      188744  293601  104858  12%             10%     11%
21      272630  314573  41943   5%              15%     12%
22      125829  377487  251658  30%             7%      14%
23      0       167772  167772  20%             0%      6%
24      0       0       0       0%              0%      0%

Total   1862005.76      2714237.44      852231.68