[ppml] IPv4 Soft Landing - Discussion andSupport/Non-SupportRequested

Ted Mittelstaedt tedm at ipinc.net
Fri Oct 5 13:38:25 EDT 2007

>-----Original Message-----
>From: ppml-bounces at arin.net [mailto:ppml-bounces at arin.net]On Behalf Of
>David Conrad
>Sent: Friday, October 05, 2007 2:25 AM
>To: <michael.dillon at bt.com>
>Cc: ppml at arin.net
>Subject: Re: [ppml] IPv4 Soft Landing - Discussion
>On Oct 5, 2007, at 1:34 AM, <michael.dillon at bt.com>
><michael.dillon at bt.com> wrote:
>>> As mentioned in a previous note, ARIN staff have told me
>>> explicitly that 100% utilization of previous allocations is an
>>> existing requirement.
>> That does not change the fact that 100% utilization is technically
>> impossible. That's probably why the existing practice is to only
>> audit the last allocation for 80% utilization and ignore all
>> previous allocations.
>The fact that you believe existing practice differs from what ARIN
>staff states is the current requirements raises interesting questions.

I think the problem here isn't in the percentages it is in the
definition of "utilization"

When filling out a address registration request I could state for
example that I have allocated a total of 32 /29's to customers.
ARIN doesen't require further justification on /29's that are allocated
to end users.  I could then claim 100% utilization on a /24.  This of course
would in no way impact the fact that I could likely go back to 80%
of the customers that those /29's are allocated to and re-subnet them
into /30s with no ill effects, and thereby generate more IP addresses
for me to use.

Or I could go into my network and remove all /30's on all serial links
and replace them with IP unnumbered, or with private addresses, to generate
further numbers.

Or I could require some customers to use translation and port forwarding
to reduce public number use.  Or require virtual websites or some such.

A "technical" full utilization would be ALL IP addresses in a given CIDR
block to be IN USE as either host IPs, network IP's or broadcast IPs.
I believe Michael was using "technically" in it's slang usage meaning
"virtually impossible in most cases from a practical standpoint"

In most production subnets it is virtually impossible in most cases from
a practical standpoint that you will get full utilization for a long enough
period of time to be able to see a IP request through.


More information about the ARIN-PPML mailing list