[ppml] Defining Utilization of IPv4 addresses

Lee Howard DeftLee at netscape.net
Thu Feb 12 11:13:37 EST 2004

I'm neither for nor against this proposal, but I'd like to understand 
better how this contrasts with existing policy.

Michael.Dillon at radianz.com wrote:

>Yet another policy proposal that will be submitted to ARIN
>in the next few days. Comments?
>1. When an ISP applies for IPv4 address space, ARIN analyzes the
>   utilization rate of any existing IPv4 address blocks allocated 
>   to the ISP.

This is consistent with current policy.

>2. For the purposes of calculating the utilization rate, any IPv4
>   address range that is assigned or allocated to another organization
>   will be counted as utilized if it meets the following two conditions.

Definition of terms: ISPs are allocated IP space, which they re-assign 
to other organizations.  You could say:

  . . . any reassignments will be considered utilized under the 
  following conditions:


>3. The assigned or allocated address range must be of a size that is
>   justified by ARIN policy.

I'm not sure what this means.  Current policy says:

  ISPs are required to apply a utilization efficiency criterion in   
  providing address space to their customers. To this end, ISPs should 
  have documented justification available for each reassignment. ARIN 
  may request this justification at any time.


>4. The ISP must require the other organization to use their addresses
>   efficiently using VLSM and CIDR technologies.

Right, as under current policy continued from above:

   ISPs reassigning IP address space to their customers should require
   their customers to use variable length subnet mask (VLSM) and 
   classless technologies (CIDR) within their networks. 


>5. The utilization rate of an address block is calculated as the 
>   number of utilized addresses divided by the total number of 
>   addresses in the block.

I find this confusing.  #5 refers to #2, essentially saying:

  The utilization rate of an address block is calculated as
  any IPv4 address range that is reassigned to another organization
  divided by the total number of addresses in the block.

So it looks to me like all the words you're using already exist in 
current policy, except that you want to change this sentence:

   ISPs must have efficiently utilized all previous allocations, 
   and at least 80% of their most recent allocation in order to 
   receive additional space. This includes all space reassigned to 
   their customers.

To read:

   ISPs must have efficiently utilized (by assignment or
   reassignment) all previous allocations, and have assigned or
   reassigned at least 80% of their most recent allocation in 
   order to receive additional space. 

Do you think there's confusion over the divisor and dividend?

It may not be explicit, but for this policy and the HD Ratio 
proposal, the network number and broadcast address are automatically
"assigned" or "utilized" when the block is reassigned.  A /30 is not
less efficient than four /32s for the purposes of utilization review.

I'm sure staff will be happy to upbraid me if I have misstated current
policy or practice.

Thanks for clarifying.


>Currently, there is no clear definition of utilization in ARIN's IPv4
>policy. The result is that different organizations interpret this in 
>different ways. This policy change is an attempt to level the playing
>field so that noone has an unfair competitive advantage due to the
>vagueness of the policy.
>This policy change only provides a clear definition for the utilization
>rate of address blocks allocated by ARIN to ISPs. It does not address the
>utilization rate of address blocks assigned to end users which would
>presumably be calculated differently by counting end devices, network
>and broadcast addresses.
>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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