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

On Sun, 2006-06-04 at 10:39 +1000, Geoff Huston wrote:

> 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.

Geoff,

I don't understand why you think my paraphrase of your document's
conclusions (including the quoted text above) is unfair or inaccurate.

What is the concern that would make such consideration (of specifying a
higher HD ratio) worthwhile?  I assume that it is address allocation
inefficiency with HD = 0.80, as suggested in your comments on Figure 4,
and the implied risk (which you have described in much more detail
elsewhere) that IPv6 unicast address space is a resource at plausible
risk of being exhausted at some point in the future, without changes to
the HD ratio.  Am I mistaken?

I've read your arguments elsewhere that we are at risk of allocating
a /1 - /4 worth of space in the next 60 years under current polices. I
don't find your arguments convincing, and further, I'm not convinced
that this would pose some sort of catastrophe, rather than the
achievement of a steady state.  And even if it is a real risk, then a
switch to /56 allocations for residential/SOHO is a preferable solution
to increasing HD, because we don't know what the design for an internet-
sized IGP would look like.

I am concerned that this document sends the wrong message to providers,
and I fear that their likely reaction to the perceived risk of tighter
allocation policies by the RIRs with be more harmful to the IPv6
internet that the potential risk of address space exhaustion.

Regards,

// Steve

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