RE: [sig-policy]Discussion document: Application of the HD-Ratio to IPv4
I was misundestanding the term heirachical as sub-allocations to
different entities, not within a single organization. I undertand your
point now. It is an interesting idea.
I am looking forward for discussions at the meeting.
Izumi
From: "Paul Wilson" <pwilson at apnic dot net>
Subject: RE: [sig-policy]Discussion document: Application of the HD-Ratio to IPv4
Date: Fri, 15 Aug 2003 13:17:34 +1000
> Thanks Izumi.
>
> > I have no objections to the idea, but the logic of large ISPs
> > requiring lower utilization rate hasn't sucken in to me yet.
>
> I will try to answer your queries here, but I also hope that the explanation
> will become clearer with my presentation at the meeting next week.
>
> > I assume network subdivion issue was addressed by considering
> > allocated addresses to to be utilized for sub-allocations. In
> > Japan, the size of allocations are not always proportionate
> > to the number of assignments either.
>
> Through discussions with large ISPs I have found that heirarchical
> management of a large address space is almost always desirable and necessary
> to some degree. Large ISPs may wish to subdivide address space according to
> the major service divisions that they operate, because those divisions may
> be autonomous and have completely separate structures; they may wish to
> further subdivide according to major regions, countries, provinces or states
> in which they operate; and they may wish to subdivide according to POPs,
> customer groupings, or other factors. A single ISP may wish to utilise
> different modes of subdivision depending on their internal architectures and
> administrative structures, which are difficult to predict; however the
> predictable fact is that with large address spaces, the need for
> hierarchical subdivision increases. This is of course the basis of the
> argument for the HD ratio.
>
> I am not arguing that these hierarchies actually do exist, because the
> degree to which an ISP can actually implement such hierarchies is highly
> constrained by the 80% utilisation requirement. Where heirarchies are
> created, management of those structures to the 80% utilisation level is
> generally very difficult; and where hierarchies are not created, management
> is also very difficult, but for other reasons.
>
> >
> > What is the biggest motivation for applying AD-ratio instead
> > of lowering a 80% fixed rate for all LIRs?
>
> As argued in RFC3194 and 1715, an HD-Ratio value represents a consistent
> level of management complexity (or "pain") regardless of the size of the
> address space. A fixed percentage value on the other hand can represent a
> very low level of complexity (for instance achieving 80% of a /24 is
> trivial) or it can represent a very high level of complexity (achieving 80%
> of a /8 is arguably extremely difficult).
>
> It seems to me that there is no necessity to lower the current 80%
> utilisation requirement for a /20 allocation, while there is a strong case
> for lowering the requirement for much larger allocations. Between these two
> extremes, there is a "sliding scale" of need, and the AD Ratio offers a
> means to calculate that scale on a fair and rational basis.
>
> I hope that helkps.
>
> Thanks.
>
> Paul.
>
>
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