|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Applying HD Ratio to all IPv4 allocations
I'm going to present the following policy change at the ARIN meeting in April. In a few days I have to submit the exact wording to ARIN and I'm looking for comments before I do this. Basically this policy loosens the rigid 80% utilization requirement in a progressive fashion to recognize the inevitable overhead of hierarchy in larger networks. 1. All requests for additional IPv4 address space shall require the efficient utilization of the sum total of all existing allocations including all space reassigned to customers, if any. 2. The HD(Host Density) ratio of the sum total 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 log(utilized IPv4 addresses) divided by log(total addresses in all previous allocations). In this formula, log refers to the natural logarithm. Rationale: The HD ratio was proposed as a way to determine allocation usage thresholds for IPv6 address allocations. For more details on this, please refer to RFC 3194 <http://www.faqs.org/rfcs/rfc3194.html>. There is some detailed background discussion about applying the HD ratio to IPv4 allocations in a proposal by Paul Wilson posted to the APNIC mailing list on Aug 7, 2003 http://www.apnic.net/mailing-lists/sig-policy/archive/2003/08/msg00000.html and he presented the it to the annual APNIC policy meeting using these slides http://www.apnic.net/meetings/16/programme/sigs/docs/policy/addpol-pres-wilson-hd-ratio.pdf I am not suggesting that ARIN should adopt the APNIC proposal and although Paul invents a new name for the HD ratio, I prefer to keep the original term. The basic thrust of this 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 is because the utilization threshold establishes a time buffer between the beginning of an ARIN application for additional addresses and the final deployment of new addresses in the operational network. By using a looser criterion as network size grows, we are also expanding this time buffer. This recognizes that the economy is more dependent than ever on the smooth running of our networks and we should not artificially force larger members to operate with virtually no safety buffers for implementing new addresses. This safety buffer size is important because larger networks have more involved processes for changes to their network and these processes take time. Paul Wilson's paper contains ample discussions of the technical justification for using the HD ratio. 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. ------------------------------------------------------- Michael Dillon Capacity Planning, Prescot St., London, UK Mobile: +44 7900 823 672 Internet: [email protected] Phone: +44 20 7650 9493 Fax: +44 20 7650 9030
|