[ppml] [address-policy-wg] 2005-01 - Last Call for Comments(HD-ratio Proposal)
Just as an aside, efficiency targets probably won't work when applied to
mobile networks. Most large global mobile (ships & planes) platforms
won't use but a much smaller fraction of the assignment. /24 is the
smallest workable unit for global movement with any currently defined
Localized mobility (trains/ferries/trucking) within a small geographical
area (or even possibly even a region) may be able to get higher
efficiencies depending on strategy/architecture.
From: Geoff Huston [mailto:gih at apnic.net]
Sent: Wednesday, February 22, 2006 7:44 PM
To: Randy Bush
Cc: ppml at arin.net; address-policy-wg at ripe.net; sig-policy at apnic.net
Subject: Re: [ppml] [address-policy-wg] 2005-01 - Last Call for
At 02:07 PM 23/02/2006, Randy Bush wrote:
> > HD Ratio Ratio Mean Std Dev
> > 0.98 1.04868 0.02285
> > 0.97 1.25899 0.03363
> > 0.96 1.45854 0.03371
> > 0.95 1.63073 0.02848
> > 0.94 1.78332 0.01859
>and what does .98 do to the flight ceiling of small folk?
I'll respond to this question, but in the interests of not wishing to
overwhelming a whole swag of mailing lists I'll make this my last
on this topic today.
An HD Ratio of 0.98 imposes a higher efficiency target than the
80% rate for all prefix sizes smaller than a /16, and lower than 80% for
allocations greater than a /16 (e.g. an HD Ratio of 0.98 implies an
efficiency threshold of 72% for a /9 allocation.)
As an example, if you had an end use population of between 3,277 and
numbered devices you would qualify for a /19 allocation under an 80%
while under an HD Ratio of 0.98 the end use population is between 3,468
6,841, corresponding to a required address efficiency level of 84% on
address block in order to qualify for a further address allocation.
The use of an HD Ratio of 0.96 corresponds to an 80% efficiency level
/24, so that 0.96 is no worse than 80% for all allocations, whereas
HD Ratios greater than 0.96 impose an efficiency constraint greater
80% on the smaller address blocks (/16 through to /24) - this can be
easily modelled on any spreadsheet of course.
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