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IPv4 Address Lifetime. Presented by Paul Wilson, APNIC Research activity conducted by Geoff Huston and supported by APNIC. IPv4 Address Lifetime Expectancy. IETF activity within the Routing and Addressing (ROAD) group in the early 1990’s - PowerPoint PPT Presentation
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IPv4 Address Lifetime
Presented by Paul Wilson, APNIC
Research activityconducted by Geoff Huston
and supported by APNIC
IPv4 Address Lifetime Expectancy
• IETF activity within the Routing and Addressing (ROAD) group in the early 1990’s– The objective was to understand the rate of
allocation of IPv4 addresses and predict the date of eventual exhaustion of the unallocated pool
– At the time the prediction was that the pool of IPv4 addresses would be exhausted around 2008-2011
• This is a re-visiting of this activity considering latest data– IETF, IANA and RIR delegations– Also, ISP announcements to the BGP routing table
Modeling the Process
1. IETF definition of IPv4– Source: IETF standards (RFCs)
• Delegation of address space for IANA administration
2. IANA allocations to RIRs– Source: IANA IPv4 Address Registry
• Allocation of /8 blocks to RIRs and others
3. RIR allocations to ISPs– Source: RIR Stats files
• Allocation of blocks to LIRs
4. ISP announcements – Source: BGP routing table
• Amount of address space advertised
Modeling the Process
IANA
RIR
Allo
catio
n
RIR
ISPA
lloca
tion
ISP
BGP
Ann
ounc
emen
t
IETF
IANA
Del
egat
ion
1. IETF Delegations
IPv4 Address Space
• Defined by the IETF– 32 bits providing 4B addresses
• The IETF has defined space for global unicast (administered by the IANA) and for other purposes
• IANA allocates space to the RIRs for further allocation and assignment
IETF Reserved, 20.1, 8%
Multicast, 16, 6%
Unicast, 219.9, 86%
IPv4 Address Space
Breakdown of IPv4 address Space by /8 block equivalents
2. IANA Allocations
IANA Allocations
• IANA allocates address space to RIRs
• The IANA IPv4 address registry records the date of each /8 allocation undertaken by the IANA
• This data has some inconsistencies– Changing IANA administration and
practices over many years
• However data is stable enough to allow some form of projection
IETF Reserved, 20.1, 8%
Multicast, 16, 6%
IANA Pool, 89, 35%
IANA Allocated, 130.9, 51%
IANA Allocations - Current
IANA Allocations - HistoricalIANA Allocated IPv4 /8 Address Blocks
0
20
40
60
80
100
120
140
Jan-91 Jan-93 Jan-95 Jan-97 Jan-99 Jan-01 Jan-03
IANA Allocations - Projection
IANA Allocated IPv4 /8 Address Blocks
100
120
140
160
180
200
220
Jan-96 Jan-98 Jan-00 Jan-02 Jan-04 Jan-06 Jan-08 Jan-10 Jan-12 Jan-14 Jan-16 Jan-18 Jan-20
IANA Allocations - Projection
• Projected date of IANA address pool exhaustion: 2020
• This projection is very uncertain because of:– Sensitivity of allocation rate to prevailing
RIR assignment policies– Sensitivity to any significant uptake up of
new applications that require end-to-end IPv4 addressing vs use of NATs
3. RIR Allocations
RIR Allocations
• RIRs allocate address space to LIRs (ISPs)
• RIR stats files records the date of each allocation to an LIR, together with the allocation details
RIR Allocations - Current
IETF Reserved, 20.1, 8%
Multicast, 16, 6%
IANA Pool, 89, 35%
RIR Pool, 14, 5%
Assigned, 116.9, 46%Allocated
RIR Allocations - Current
Address Allocation Status - by /8
0
2000000
4000000
6000000
8000000
10000000
12000000
14000000
16000000
Reserved
IANA
Unallocated
Allocated
RIR Allocations - Historical
RIR Assigned IPv4 /8 Address Blocks
0
20
40
60
80
100
120
Jan-83 Jan-85 Jan-87 Jan-89 Jan-91 Jan-93 Jan-95 Jan-97 Jan-99 Jan-01 Jan-03
RIR Allocations - Projection
RIR Assigned IPv4 /8 Address Blocks - Projection
80
100
120
140
160
180
200
220
Jan-96 Jan-98 Jan-00 Jan-02 Jan-04 Jan-06 Jan-08 Jan-10 Jan-12 Jan-14 Jan-16 Jan-18 Jan-20 Jan-22 Jan-24 Jan-26
RIR Allocations - Projection
• Projected date of RIR address pool exhaustion: 2027
• The projection has the same levels of uncertainty as noted for the IANA projections:– RIR management policies– Technological developments
4. BGP Routing Table
BGP Routing Table
• The BGP routing table spans a set of advertised addresses– Representing addresses in use by ISPs
• A similar analysis of usage and projection can be undertaken on this data
• Assumption: BGP routing table represents actual IP address usage– Therefore it “drives” the other trends
BGP Routing Table - Current
IETF Reserved, 20.1, 8%
Multicast, 16, 6%
IANA Pool, 89, 35%
RIR Pool, 14, 5%
Assigned, 42.4, 17%
Advertised, 74.5, 29%
BGP Announcements - Current
Address Allocation Status - by /8
0
2000000
4000000
6000000
8000000
10000000
12000000
14000000
16000000
Reserved
IANA
Unallocated
Unadvertised
Advertised
BGP Announcements - HistoricalBGP Table - Address Span
0
50
100
150
200
Nov
/99
Jan/
00
Mar
/00
May
/00
Jul/0
0
Sep
/00
Nov
/00
Jan/
01
Mar
/01
May
/01
Jul/0
1
Sep
/01
Nov
/01
Jan/
02
Mar
/02
May
/02
Jul/0
2
Sep
/02
Nov
/02
Jan/
03
Mar
/03
May
/03
BGP Announcements - ProjectionBGP Announced Address Space - Projection
0
50
100
150
200
Jan/
00
Jan/
01
Jan/
02
Jan/
03
Jan/
04
Jan/
05
Jan/
06
Jan/
07
Jan/
08
Jan/
09
Jan/
10
Jan/
11
Jan/
12
Jan/
13
Jan/
14
Jan/
15
Jan/
16
Jan/
17
Jan/
18
Jan/
19
Jan/
20
Jan/
21
Jan/
22
Jan/
23
Jan/
24
Jan/
25
Jan/
26
Jan/
27
Jan/
28
BGP Announcements - Projection
• Projected date of address pool exhaustion according to BGP: 2027
• This projection uses a 3 year data baseline to obtain the projection– This is much shorter baseline than the
IANA and RIR projections– There are, again, considerable
uncertainties associated with this projection
BGP Announcements - Projection
• Comments received about this projection have prompted a more detailed analysis of the BGP data
• It appears that there is a different view that can be formed from the data
• Firstly, here’s the raw data – hourly measurements over 3 years…
Another look at that BGP data…
Another look at that BGP data…
• The most obvious noise comes from flaps in /8 advertisements.
• The first step was to remove this noise by recalculating the address data using a fixed number of /8 advertisements
• The value of 19 was used to select one of the ‘tracks’ in the data
Another look at that BGP data…Filter to 19 /8s
980000000
1030000000
1080000000
1130000000
1180000000
1230000000
Nov-99 Mar-00 Jul-00 Nov-00 Mar-01 Jul-01 Nov-01 Mar-02 Jul-02 Nov-02 Mar-03 Jul-03
Another look at that BGP data…
• This is still noisy, but there is no systematic method of raw data grooming that can efficiently reduce this noise
• Now use gradient smoothing, limiting the absolute values of the first order differential of the data (gradient limiting) to smooth the data
Another look at that BGP data…Gradient Filtered Data
980000000
1030000000
1080000000
1130000000
1180000000
1230000000
Nov-99 Mar-00 Jul-00 Nov-00 Mar-01 Jul-01 Nov-01 Mar-02 Jul-02 Nov-02 Mar-03 Jul-03
Another look at that BGP data…
• Now, further smoothing is needed to reduce the data set to allow projection models to be generated
• The technique used is a sliding window average, with a window of 1501 entries
Another look at that BGP data…Smoothed Average
980000000
1030000000
1080000000
1130000000
1180000000
1230000000
Nov-99 Mar-00 Jul-00 Nov-00 Mar-01 Jul-01 Nov-01 Mar-02 Jul-02 Nov-02 Mar-03 Jul-03
Another look at that BGP data…Linear Squares Best Fit
58
60
62
64
66
68
70
72
74
Nov-99 Feb-00 May-00 Aug-00 Nov-00 Feb-01 May-01 Aug-01 Nov-01 Feb-02 May-02 Aug-02 Nov-02 Feb-03 May-03 Aug-03
Another look at that BGP data…
• First order differential of total BGP announcement– Until 2000, exponential (accelerating)
growth– Since 2000, oscillating differential and
overall deceleration– Last 6 months, differential approaching 0
(i.e. no growth)
• Linear fit seems most appropriate for this data
Another look at that BGP data…daily rate of change in address growth per month
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
Dec-99 Mar-00 Jun-00 Sep-00 Dec-00 Mar-01 Jun-01 Sep-01 Dec-01 Mar-02 Jun-02 Sep-02 Dec-02 Mar-03 Jun-03
Combining the Data
Combining the DataIPv4 Address Space
0
20
40
60
80
100
120
140
Jan-83 Jan-85 Jan-87 Jan-89 Jan-91 Jan-93 Jan-95 Jan-97 Jan-99 Jan-01 Jan-03
IANA
RIR
BGP
Recent DataIPv4 Address Space
0
20
40
60
80
100
120
140
Dec-99 Mar-00 Jun-00 Sep-00 Dec-00 Mar-01 Jun-01 Sep-01 Dec-01 Mar-02 Jun-02 Sep-02 Dec-02 Mar-03 Jun-03
IANA
RIR
BGP
Holding Pools
Holding Pools:RIR & Unannounced Space
Size of Holding Areas (/8)
0
5
10
15
20
25
30
35
40
45
50
Nov-99 Feb-00 May-00 Aug-00 Nov-00 Feb-01 May-01 Aug-01 Nov-01 Feb-02 May-02 Aug-02 Nov-02 Feb-03 May-03
UnAnn
RIR
Modeling the Process
• Assume that the RIR efficiency in allocation slowly declines, so that the amount of RIR-held space increases over time
• Assume that the Unannounced space shrinks at the same rate as shown over the past 3 years
• Assume an exponential best fit model to the announced address space projections and base RIR and IANA pools from the announced address space projections, using the above 2 assumptions
IPv4 Model
0
50
100
150
200
Jan-00 Jan-05 Jan-10 Jan-15 Jan-20 Jan-25
IANA
RIR
BGP
IANA-P
RIR-P
BGP-P
RIR
LIR
Modeling the Process - Exponential
Projections
IANA Pool Exhaustion 2022
RIR Pool Exhaustion 2024
Modeling the Process - LinearIPv4 Model
0
50
100
150
200
Jan-00 Jan-05 Jan-10 Jan-15 Jan-20 Jan-25 Jan-30 Jan-35 Jan-40 Jan-45
IANA
RIR
BGP
IANA-P
RIR-P
BGP-P
RIR
LIR
Projections
IANA Pool Exhaustion 2030
RIR Pool Exhaustion 2037
Observations
• Extrapolation of current allocation practices and BGP-based demand model
• Derived from 2000-2003 data• Considering
– IANA/RIR unallocated pool– Total address space including allocated but
unannounced
• Assuming exponential growth– Address space lasts until 2025, or up to 2029
• Assuming linear growth– Address space lasts until 2037 - 2047
Issues
• This is just a model - reality will be different!• Will the BGP routing table continue to reflect
allocation rates? • Is the model of the unadvertised pools and
RIR holding pools appropriate?• Externalities…
– What are the underlying growth drivers (applications) and how are these best modeled?
– What forms of disruptive events would alter this model, and to what extent?