[arin-ppml] 2010-8: Rework of IPv6 assignment criteria

[Owen DeLong]

> 
>> The HD-Ratio is replaced with a simplified 75% utilization threshold 
>> based on nibble boundaries for end-user assignments.   This threshold is 
>> somewhat more restrictive for larger assignments, while slightly less 
>> restrictive for the smaller /44 assignments, than the HD-Ratio. 
>> However, in both cases it is much easier for an end-user to understand 
>> the policy criteria that applies to them.
> 
> This means that a different type of measure would be applied to allocations made to ISPs and assignments made to end users. Presumably, the reason for the difference is not that end user organizations are not capable of understanding the HD-ratio concept. And anyway, if it is difficult to understand, ARIN can be asked to produce explanatory materials.
> 
> If the concept underlying the HD-ratio is fair, is it fair not to use that concept when calculating the amount of space available to an end-user organization?
> 
Leo,

HD-Ratio is intended to take into account the losses due to hierarchy inherent in scaling provider networks.

End user networks tend to be flatter (within a given site) and thus not subject to those losses.

As such, we felt that a simpler, easier to understand guideline was more appropriate to the circumstance.
I'm not 100% convinced HD Ratio i a particularly good measure for ISPs, but, that's not the policy section
we're fixing with this proposal. Certainly, I don't think it makes sense to saddle the end user policy with
this metric just because it hasn't been used for ISPs as yet.

Owen