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[AfriNIC-rpd] Propose Policy Change: IPv6 HD-Ratio (afpol-ipv6hdr20070330)

Adiel A. Akplogan adiel at afrinic.net
Fri Mar 30 23:49:57 UTC 2007


Name: Adiel A. Akplogan
Organisation: AfriNIC
Policy Afected: IPv6 Allocation policy (afpol-v6200407-000)

Date: 30/03/2007

Proposal: Change to the IPv6 HD ratio from 0.8 to 0.94

Rational:
=========

The current IPv6 Address Allocation and Assignment Policy (afpol-v6200407-000)
suggests that most IPv6 subscribers should be assigned a /48 "in the 
general case".
The policy also requests AfriNIC to evaluate requests for additional 
allocations
based on "units of /48 assignments" and that LIRs be allocated in 
general a /32.

Contrary to IPv4 where only utilization determines the level of 
consumption hence
the threshold for subsequent allocations (80% host based utilization), in the
IPv6 Policy efficient address space utilization threshold is used to determine
eligibility to subsequent allocations. The HD-Ratio is a way of measuring the
efficiency of address assignment [RFC 3194]:

          Log (number of allocated objects)
   HD = ------------------------------------------
        Log (maximum number of allocatable objects)

The efficiency utilization threshold (T) is expressed as a number of 
individual
/48 prefixes allocated from an IPv6 prefix (P). It can be calculated as:

        ((48-P)*HD)
   T = 2

The HD-Ratio presently defined for IPv6 is at 0.8.

This has the effect of making subsequent allocations to LIRs after only 10.9%
utilization of their available space. If the allocation prefix is brought down
to /20 the efficient utilization threshold  will only be 2.1% using  the HD
ratio of 0.80. Based on this, the LIRs will have much more unused IP addresses
than they really need for their efficient growth planning. (See ANNEX 1).

This policy proposal suggests to raise the HD ratio from 0.80 to 0.94. Doing
this could allow  to reduce by 3 bit the consumption of whole IPv6 address
space over the next 50 years. An LIR will then qualify for a subsequent
allocation only when its uses (for a /32) 51.41% of its allocation.

See 
http://smakd.potaroo.net/ietf/all-ids/draft-narten-iana-rir-ipv6-considerations-00.txt 

for more analysis on Issues Related to the Management of IPv6 Address Space.

** Similar adjustment of the HD-Ration has been adopted in the other
RIR regions **


ANNEX 1
========

A) With an HD=0.8

The following table provides equivalent absolute and percentage address
utilization figures for IPv6 prefixes, corresponding to an HD-Ratio of 0.8


         P       48-P            Total /48s     Threshold    Util%

         48       0                   1                1     100.0%
         47       1                   2                2      87.1%
         46       2                   4                3      75.8%
         45       3                   8                5      66.0%
         44       4                  16                9      57.4%
         43       5                  32               16      50.0%
         42       6                  64               28      43.5%
         41       7                 128               49      37.9%
         40       8                 256               84      33.0%
         39       9                 512              147      28.7%
         38      10                1024              256      25.0%
         37      11                2048              446      21.8%
         36      12                4096              776      18.9%
         35      13                8192             1351      16.5%
         34      14               16384             2353      14.4%
         33      15               32768             4096      12.5%
         32      16               65536             7132      10.9%
         31      17              131072            12417       9.5%
         30      18              262144            21619       8.2%
         29      19              524288            37641       7.2%
         28      20             1048576            65536       6.3%
         27      21             2097152           114105       5.4%
         26      22             4194304           198668       4.7%
         25      23             8388608           345901       4.1%
         24      24            16777216           602249       3.6%
         23      25            33554432          1048576       3.1%
         22      26            67108864          1825677       2.7%
         21      27           134217728          3178688       2.4%
         20      28           268435456          5534417       2.1%
         19      29           536870912          9635980       1.8%
         18      30          1073741824         16777216       1.6%
         17      31          2147483648         29210830       1.4%
         16      32          4294967296         50859008       1.2%
         15      33          8589934592         88550677       1.0%
         14      34         17179869184        154175683       0.9%
         13      35         34359738368        268435456       0.8%
         12      36         68719476736        467373275       0.7%
         11      37        137438953472        813744135       0.6%
         10      38        274877906944       1416810831       0.5%
          9      39        549755813888       2466810934       0.4%
          8      40       1099511627776       4294967296       0.4%
          7      41       2199023255552       7477972398       0.3%
          6      42       4398046511104      13019906166       0.3%
          5      43       8796093022208      22668973294       0.3%
          4      44      17592186044416      39468974941       0.2%

B) with an HD=0.94

The following table provides equivalent absolute and percentage address
utilization figures for IPv6 prefixes, corresponding to an HD-Ratio of
0.94.

         P        48-P            Total /48s      Threshold    Util%

         		     		
         48	      0	                 1                1     100.00%
         47	      1	                 2                2     95.93%
         46	      2	                 4                4     92.02%
         45	      3	                 8                7     88.27%
         44	      4	                16               14     84.67%
         43	      5	                32               26     81.23%
         42	      6	                64               50     77.92%
         41	      7	               128               96     74.74%
         40	      8	               256              184     71.70%
         39	      9	               512              352     68.78%
         38	     10	              1024              676     65.98%
         37	     11	              2048             1296     63.29%
         36	     12	              4096             2487     60.71%
         35	     13	              8192             4771     58.24%
         34	     14	             16384             9153     55.86%
         33	     15	             32768            17560     53.59%
         32	     16	             65536            33689     51.41%
         31	     17	            131072            64634     49.31%
         30	     18	            262144           124002     47.30%
         29	     19	            524288           237901     45.38%
         28	     20	           1048576           456419     43.53%
         27	     21	           2097152           875653     41.75%
         26	     22	           4194304          1679965     40.05%
         25	     23	           8388608          3223061     38.42%
         24	     24	          16777216          6183533     36.86%
         23	     25	          33554432         11863283     35.36%
         22	     26	          67108864         22760044     33.92%
         21	     27	         134217728         43665787     32.53%
         20	     28	         268435456         83774045     31.21%
         19	     29	         536870912        160722871     29.94%
         18	     30	        1073741824        308351367     28.72%
         17	     31	        2147483648        591580804     27.55%
         16	     32	        4294967296       1134964479     26.43%
         15	     33	        8589934592       2177461403     25.35%
         14	     34	       17179869184       4177521189     24.32%
         13	     35	       34359738368       8014692369     23.33%
         12	     36	       68719476736      15376413635     22.38%
         11	     37	      137438953472      29500083768     21.46%
         10	     38	      274877906944      56596743751     20.59%
          9	     39	      549755813888     108582451102     19.75%
          8	     40	     1099511627776     208318498661     18.95%
          7	     41	     2199023255552     399664922315     18.17%
          6	     42	     4398046511104     766768439460     17.43%
          5	     43	     8796093022208    1471066903609     16.72%
          4	     44	    17592186044416    2822283395519     16.04%    





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