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

Member Services memsvcs at arin.net
Wed May 25 08:09:55 EDT 2005

On May 19, 2005, the ARIN Advisory Council (AC) concluded its review of
proposed policy 'IPv6 HD ratio' and agreed to forward it as a formal
proposal for discussion by the community. This proposal is designated
2005-5: IPv6 HD ratio. The policy proposal text is below and can be found


All persons in the community are encouraged to discuss policy proposal
2005-5 in the weeks leading to the ARIN Public Policy Meeting in Los
Angeles, CA, scheduled for October 26-28, 2005. Both the discussion on the
PPML and at the public policy meeting will be used to determine the
community consensus regarding this policy proposal.

The ARIN Internet Resource Policy Evaluation Process can be found at:

ARIN's Policy Proposal Archive can be found at: 



Member Services 
American Registry for Internet Numbers (ARIN) 

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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%.

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.

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