Re: Last Call: 'Considerations on the IPv6 Host density Metric' to Informational RFC (draft-huston-hd-metric)

At 01:33 PM 3/06/2006, Steven Blake wrote:
>I am concerned about the conclusion reached in this document (that HD
>ratios > 0.8 and closer to 0.94 should be considered when making address
>allocations to larger providers).

This is a topic of interest both to the IETF and to regional addressing 
policy fora, and some care needs to be taken in reaching an understanding 
of relative roles.

As compared to your opening statement relating to the conclusion of this 
document, I must correct you  by noting that this document makes NO 
specific recommendation as to an optimal HD Ratio value to be used in the 
context of a threshold address utilization efficiency metric. This document 
provides a refinement to the work reported in RFC1715, RFC 3177 and RFC 
3194 that recommended the use of an HD Ratio of 0.8 for assessment of 
threshold address utilization efficiencies in an address allocation 
context. The refinement proposed in this document is, and I quote:

   "This study concludes that consideration should be given to the
    viability of specifying a higher HD-Ratio value as representing a
    more relevant model of internal network structure, internal routing
    and internal address aggregation structures in the context of IPv6
    network deployment."

Your representation as to the document's conclusions is simply not 
supported by the document itself.

>  I believe that:
>
>(1) this would not solve a real problem,

I must disagree with this perspective.

This document observes that there is a body of opinion and some evidence 
that suggests  that the conclusions and recommendations in RFC1715 and 
3177, using a metric defined in RFC3194, may not be altogether appropriate 
in the context of deployment of public Internet infrastructure. I am of the 
view, that yes, this is a topic worthy of some further study and associated 
reporting of this perspective.

>(2) it is risky to infer too much from existing network design
>     practice when considering future provider networks that may
>     be much larger, and

As this document concludes by pointing out that this is an area for further 
study it is hard to see where this comment and the document differ 
substantively.

>(3) there is a better solution to the alleged problem.

This document does not represent a "solution". Whether you believe that 
there is a "better" address utilization threshold efficiency metric than 
the HD Ratio, or not, is not exactly the major point of this document. This 
document points out that there is a body of evidence that suggests that use 
of an HD Ratio of 0.8 is a poor metric and that its is an area for further 
study to determine what an appropriate metric may be.

As to where such a study may be conducted, my above observation about the 
relative roles of the IETF and regional addressing policy fora was intended 
to illustrate the perspective that such a topic may well be best conducted 
not in the IETF but in these addressing policy fora. Accordingly, I 
strongly suspect that the remainder of your comments may well be best 
presented in these fora rather than the IETF.

regards,

     Geoff

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