Policy Proposal 2003-10: Apply the HD Ratio to All Future IPv4 Allocations

Status: Abandoned

Tracking Information

Discussion Tracking

Mailing List:

Formal introduction on PPML on 21 August 2003

Public Policy Mailing List

ARIN Public Policy Meeting:


ARIN Advisory Council:

23 October 2003

ARIN Board of Trustees:

BoT Meetings




Michael Dillon

Proposal to apply the HD ratio to all future IPv4 allocations.

  1. All requests for additional IPv4 address space shall require the efficient utilization of all previous allocations including all space reassigned to customers, if any.
  2. The HD(Host Density) ratio of all previous allocations shall be greater than or equal to .966 and the HD ratio of the most recent allocation shall be greater than or equal to .930 in order to receive additional space.
  3. The HD ratio is calculated as log10(utilized IPv4 addresses)/log10(totall addresses in all previous allocations). In this formula, log10 refers to the base 10 logarithm.

Discussion of the proposal.

For more details on the HD ratio, please refer to RFC 3194 http://www.faqs.org/rfcs/rfc3194.html and to a proposal by Paul Wilson posted to the APNIC mailing list on the 7th of August 2003 http://www.apnic.net/mailing-lists/sig-policy/archive/2003/08/

The basic thrust of my proposal is to replace the rigid 80% usage criterion by the more flexible HD ratio and to shift the emphasis away from the last allocated block to include the total allocated address space. To that end, the .930 criterion for the last block is a lot looser than the existing requirements for the last block. This recognizes that the economy is more dependent than ever on the smooth running of our networks and we should not artificially force members to operate with virtually no safety buffers for implementing new addresses.

Paul Wilson's paper contains ample discussions of the justification for using the HD ratio. I prefer to retain the same name for the ratio as RFC 3194 and although I have proposed that we use the .966 number that he suggests, I believe there may be valid arguments for reducing this slightly, perhaps to .960.

It would be good for ARIN to have more detailed discussion of the HD ratio on file however I don't believe that needs to be in the policy itself. However, I would suggest that the ARIN website should contain a copy of RFC 3194, a copy of Paul Wilson's paper, and a summary of any ARIN member discussions regarding application of the HD ratio to IPv4 addresses.

Timetable for implementation

I suggest that this proposal should be implemented within 30 days of a decision by a members meeting.

Michael Dillon
Capacity Planning, Prescot St., London, UK
Mobile: +44 7900 823 672 Internet: michael.dillon at radianz.com
Phone: +44 20 7650 9493 Fax: +44 20 7650 9030

Note: On 9/12/2003 the apnic.net url above was corrected to fix typographical error.