ipv4 address lifetime expectancy revisited - revisited
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IPv4 Address Lifetime Expectancy Revisited - Revisited. Geoff Huston November 2003 Presentation to the IEPG Research activity supported by APNIC. - PowerPoint PPT PresentationTRANSCRIPT
IPv4 Address Lifetime ExpectancyRevisited - Revisited
Geoff HustonNovember 2003
Presentation to the IEPG
Research activitysupported by APNIC
The Regional Internet Registries s do not make forecasts or predictions about number resource lifetimes. The RIRs provide statistics of what has been allocated. The following presentation is a personal contribution based on extrapolation of RIR allocation data.
IPv4 Address Lifetime Expectancy
In July the IEPG presentation on address lifetime expectancy used the rate of growth of BGP advertised address space as the overall address consumption driver
The presentation analyzed the roles of the IANA and the RIRs and created an overall model of address consumption
IPv4 Model
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IANARIRBGPIANA-PRIR-PBGP-PRIRLIR
Modelling the Process – July 2003
Projections
IANA Pool Exhaustion 2022RIR Pool Exhaustion 2024
Address Consumption Models The basic assumption was that continued
growth will remain at a constant proportion of the total advertised address space (compound growth), and that as a consequence address exhaustion was predicted to occur sometime around 2025
Does the advertised address data support this view of the address growth model?
The Advertised Address Space
Notes It’s noisy data
There are 3 /8 prefixes that flap on a multi-day cycle
There are shorter term flaps of smaller prefixes
Reduce the noise by: Removing large steps Applying gradient filter Apply averaging to smooth the data
Smoothed Data (1)Filter to 18 /8 advertisements
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Smoothed Data (2)Gradient Filtered
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Model MatchingApplying Models to the Data
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DataLinearPolynomial
But Which Model? A number of models can be
applied to this data: Linear model, assuming a constant
rate of growth Polynomial model, assuming a
constant rate of change of growth Exponential model, assuming a
geometric growth with a constant doubling period
First Order Differential of the data
First Order Differential
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Linear Best Fit to Differential
Least Squares Best Fit
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Growth Rate The growth rate of 4 – 5 /8 blocks
per year in 99-00 is now approximately half that, at 2 – 3 /8 blocks per year
A constant growth model has a best fit of 3.5 /8 blocks per year
The change in growth over the period is a decline in growth rate by 0.4 /8 blocks per year
Log of DataLog of smoothed data
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Best Fit to LogBest Fit to Log Data
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Exponential Model The exponential model assumes a
liner best fit to the log of the data series
This linear fit is evident across 2000 More recent data shows a negative
declining rate in growth of the log of the data.
ProjectionsProjections
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LinearX**2 PolynomialExponentialAverage Data
Observations Polynomial best fit sees a continuing
decline in growth until growth reaches zero in 2010 Matches a model of market saturation
Exponential best fit sees continuing increase in growth until exhaustion occurs in 2021 Matches a model of uniform continued growth in
all parts of the network Linear best fit sees constant growth until
exhaustion occurs in 2042 Matches a model of progressive saturation in
existing markets offset by demands in new markets
Modelling the Process Assume that the RIR efficiency in allocation
slowly declines, then the amount of RIR-held space increases over time
Assume that the Unannounced space shrinks at the same rate as shown over the past3 years
Assume linear best fit model to the announced address space projections and base RIR and IANA pools from the announced address space projections
Modelling the ProcessIPv4 Model
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IANARIRBGPIANA-PRIR-PBGP-PRIRLIR
Projections
IANA Pool Exhaustion 2030RIR Pool Exhaustion 2037
Unadvertised Address Pool
RIR Holding Pool
Observations Extrapolation of current allocation practices and current
demand models using an exponential growth model derived from a 2000 – 2003 data would see RIR IPv4 space allocations being made for the next 2 decades, with the unallocated draw pool lasting until 2018 - 2020
The use linear growth model sees RIR IPv4 space allocations being made for the next 3 decades, with the unallocated draw pool lasting until 2030 – 2037
Re-introducing the held unannounced space into the routing system over the coming years would extend this point by a further decade, prolonging the useable lifetime of the unallocated draw pool until 2038 – 2045
This is just a model
Questions Externalities:
What are the underlying growth drivers and how are these best modeled?
What forms of disruptive events would alter this model?
What would be the extent of the disruption (order of size of the disruptive address demand)?