[ppml] HD Ratio changes

Patrick Grosso arin at patrickgrosso.com
Tue Feb 10 18:38:30 EST 2004


This is not a proposed addition to the policy, but rather a commentary
on the issue.  Please excuse me if I do not understand all of the

The HD Ratio Policy seems to be getting complicated.  We should keep
things SIMPLE.  Especially since there will be newcomers to the ARIN
policies that will need to learn how to adopt our practices in a short
period of time.

I prefer % utilization over a log function, because a log function will
be prejudicially favorable to either the "small provider" or the "large
provider" which ever way the function works.  An IP address is an IP
address, no matter who is allocating or assigning it.

When I was requesting address space from ARIN under the web hosting
policy, we only had to prove 80% utilization for our previous
allocation.  Efficient utilization of prior allocations was preferred
but not necessary (and was not checked).  Although we efficiently
utilized that space, it is possible that other providers did not.

Given that possibility, I pose these questions:

Can it be said that the rediscovery and repair of previous allocations
inefficiencies (or rather their inclusion towards current utilization
rates) could prove more fruitful in the quest for IPv4 address space? 

If a new policy is ratified, will it only apply to new allocations?  If
so then we are only talking about a small scope of addresses (those that
are "saved" from the remaining allocations to come (although I am not
discounting this issue, because it is important as well).


Where I can see some technical limitations on reassigning past customer
(churned) address space due to the way a network has be subnetted, I see
no problem in efficiently reassigning those subnets under the web
hosting policy (or dial, dsl, etc).  I believe that better practices (of
both ARIN and ISP) during the additional request process will provide a
far greater gain.  Practices that would include the (true) inclusion of
previously allocated address space, and the more meticulous weeding out
of 'ghost' reassignments (SWIP's of customers that are no longer there).
Rather than rehash an existing policy, I think we should look elsewhere
for NEW ways to extend the life of our IPv4 address space, both old and
new. (And enforce those measures).


Patrick Grosso

-----Original Message-----
From: owner-ppml at arin.net [mailto:owner-ppml at arin.net] On Behalf Of
Michael.Dillon at radianz.com
Sent: Tuesday, February 10, 2004 7:05 AM
To: ppml at arin.net
Subject: [ppml] HD Ratio changes

I've made some changes to the wording of the policy. First of all
I've made the use of the HD Ratio optional. Secondly, I've decided
to use the natural logarithm in the calculation because PERL has
this and not the base 10 logarithm. The end result of the ratio
calculation is identical, but now people will see that is clearly
is easy to add the calculation to PERL IP address management
systems. The Excel function LN(x) is the same as PERL's log(x).
And lastly, I've pulled out the mention of reassignments since
any definition of utilization belongs elsewhere and this was
getting too close.

1. Anyone who has already been allocated 4096 IPv4 addresses or
   more may choose to have additional requests for IPv4 addresses
   evaluated using an HD (Host Density) Ratio calculation to determine 
   sufficient utilization instead of a fixed percentage threshold.

2. All requests for additional IPv4 address space subject to the HD 
   Ratio shall require the efficient utilization of the sum total of 
   all existing allocations. The HD Ratio on the sum total of all 
   existing allocations must be greater than or equal to .966.

3. In addition, the HD ratio of the most recent allocation must be 
   greater than or equal to .930.

4. 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.

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

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