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

Member Services memsvcs at arin.net
Mon Oct 31 13:05:46 EST 2005

The ARIN Advisory Council (AC), acting under the provisions of the ARIN
Internet Resource Policy Evaluation Process (IRPEP), has reviewed policy
proposal 2005-5 and has determined that there is community consensus in
favor of the proposal to move it to last call. The AC made this
determination at their meeting at the conclusion of the ARIN Public
Policy meeting on October 27, 2005. The results of the AC meeting were
reported by the Chair of the AC at the member meeting. This report can
be found at

The policy proposal text is provided below and is also available at

Comments are encouraged. All comments should be provided to
ppml at arin.net. This last call will expire at 12:00 Noon, Eastern Time,
November 15, 2005.

The ARIN Internet Resource Policy Evaluation Process can be found at


Member Services
American Registry for Internet Numbers (ARIN)


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.

Policy Rationale

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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