[ppml] Policy Proposal 2005-5: IPv6 HD ratio

Edward Lewis Ed.Lewis at neustar.biz
Wed May 25 11:14:06 EDT 2005

At 8:09 -0400 5/25/05, Member Services wrote:

>Policy Proposal 2005-5: IPv6 HD ratio
>Author: Andrew Dul
>Policy term: permanent
>Policy statement: Change HD ratio used for IPv6 allocations to 0.94
>This would modify sections & 6.7 (including the HD-ratio to
>percentage table) of the NRPM.
>Rationale: Recent research has shown that based upon certain growth models
>the current IPv6 allocation policy using the HD ratio of 0.8 will allocate
>between a /1 and /4 of Ipv6 address space over the period of about 60 years.
>By changing the HD ratio to 0.94, this would require LIRs to have a higher
>utilization of the /48s that are assigned to end sites before being able to
>obtain additional allocations.  This policy would change the threshold for
>an LIR holding a /32 from approximately 11% to 51%.
>An LIR with a /20 would have a utilized percentage of approximately 31% vs.
>the current 2%.

I have two questions, not addressed in the ID referenced above. 
(Note that the document at that URL will expire before the October 
meeting.  I would therefore encourage PPML'ers to help get the draft 
through to the RFC Editor to become a document that can be 
permanently referenced.)

1) Will the tightening of the HD-ratio mean that ARIN will have to 
turn around addressing requests faster?  I am not saying there is a 
problem now, but raising the HD-ration means that I would have to 
delay asking for new space until I passed the 0.8 threshold and until 
I hit the new one.  Delaying here means losing lead time from request 
to need to use.

2) Will the tightening of the HD-ratio mean a significantly more 
dense use of the space resulting in more incidents of end-user 
renumbering if their needs grow?

Another question I have is related to what is in the draft.  The 
draft illustrates the benefits of a 0.94 HD-ratio over 0.8, but I 
don't see that 0.94 is established as "optimal."  Why not 0.93?  0.95?

Quoting the conclusions of the draft:

"It is recommended that further study of address efficiency metrics
    and the relationship between network structure and address efficiency
    models considered as part of such a study.  Consideration should be
    given to the viability of specifying a higher HD-Ratio value as
    representing a more relevant model of internal network structure,
    internal routing and internal address aggregation structures."

The conclusions section mentions only the 0.8 HD-ratio.  The 
conclusions do not mention 0.94 at all.

>This policy may also prevent the hoarding of IPv6 addresses by current
>organizations with large customer bases, but no substantial current IPv6
>Timetable for implementation: Within 30 days of ratification by the BoT.

Edward Lewis                                                +1-571-434-5468

If you knew what I was thinking, you'd understand what I was saying.

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