Policy 2005-5: IPv6 HD ratio

Status: Adopted - NRPM Sections and 6.7

Tracking Information

Discussion Tracking

Mailing List:

Formal introduction on PPML on 25 May 2005

Last call from 31 October through 15 November 2005 Public Policy Mailing List

ARIN Public Policy Meeting:


ARIN Advisory Council:

19 May 2005
21 July 2005
18 August 2005
27 October 2005
17 November 2005

ARIN Board of Trustees:

12 February 2006



17 February 2006


Andrew Dul

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.


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 network.

Timetable for implementation: Within 30 days of ratification by the BoT.