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
– 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
IETF
RIR
RIR
ISP
Announcement
IANA
ISP
Allocation
Allocation
Delegation
IANA
BGP
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
IPv4 Address Space
IETF Reserved, 20.1, 8%
Multicast, 16, 6%
Unicast, 219.9, 86%
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
IANA Allocations - Current
IETF Reserved, 20.1, 8%
Multicast, 16, 6%
IANA Allocated, 130.9, 51%
IANA Pool, 89, 35%
IANA Allocations - Historical
IANA Allocated IPv4 /8 Address Blocks
140
120
100
80
60
40
20
0
Jan-91
Jan-93
Jan-95
Jan-97
Jan-99
Jan-01
Jan-03
IANA Allocations - Projection
IANA Allocated IPv4 /8 Address Blocks
220
200
180
160
140
120
100
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%
Assigned, 116.9, 46%
Allocated
IANA Pool, 89, 35%
RIR Pool, 14, 5%
RIR Allocations - Current
Address Allocation Status - by /8
16000000
14000000
12000000
10000000
Reserved
IANA
Unallocated
Allocated
8000000
6000000
4000000
2000000
96
10
4
11
2
12
0
12
8
13
6
14
4
15
2
16
0
16
8
17
6
18
4
19
2
20
0
20
8
21
6
22
4
23
2
24
0
24
8
88
80
72
64
56
48
40
32
24
8
16
0
0
RIR Allocations - Historical
RIR Assigned IPv4 /8 Address Blocks
120
100
80
60
40
20
0
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
220
200
180
160
140
120
100
80
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%
Advertised, 74.5, 29%
IANA Pool, 89, 35%
Assigned, 42.4, 17%
RIR Pool, 14, 5%
BGP Announcements - Current
Address Allocation Status - by /8
16000000
14000000
12000000
10000000
Reserved
IANA
Unallocated
Unadvertised
Advertised
8000000
6000000
4000000
2000000
96
10
4
11
2
12
0
12
8
13
6
14
4
15
2
16
0
16
8
17
6
18
4
19
2
20
0
20
8
21
6
22
4
23
2
24
0
24
8
88
80
72
64
56
48
40
32
24
8
16
0
0
May/03
Mar/03
Jan/03
Nov/02
Sep/02
Jul/02
May/02
Mar/02
Jan/02
Nov/01
Sep/01
Jul/01
May/01
Mar/01
Jan/01
Nov/00
Sep/00
Jul/00
May/00
Mar/00
Jan/00
Nov/99
BGP Announcements - Historical
BGP Table - Address Span
200
150
100
50
0
Jan/28
Jan/27
Jan/26
Jan/25
Jan/24
Jan/23
Jan/22
Jan/21
Jan/20
Jan/19
Jan/18
Jan/17
Jan/16
Jan/15
Jan/14
Jan/13
Jan/12
Jan/11
Jan/10
Jan/09
Jan/08
Jan/07
Jan/06
Jan/05
Jan/04
Jan/03
Jan/02
Jan/01
Jan/00
BGP Announcements - Projection
BGP Announced Address Space - Projection
200
150
100
50
0
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
1230000000
1180000000
1130000000
1080000000
1030000000
980000000
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
1230000000
1180000000
1130000000
1080000000
1030000000
980000000
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
1230000000
1180000000
1130000000
1080000000
1030000000
980000000
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
74
72
70
68
66
64
62
60
58
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
0.016
0.014
0.012
0.010
0.008
0.006
0.004
0.002
0.000
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 Data
IPv4 Address Space
140
120
100
80
IANA
RIR
BGP
60
40
20
0
Jan-83
Jan-85
Jan-87
Jan-89
Jan-91
Jan-93
Jan-95
Jan-97
Jan-99
Jan-01
Jan-03
Recent Data
IPv4 Address Space
140
120
100
80
IANA
RIR
BGP
60
40
20
0
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
Holding Pools
Holding Pools:
RIR & Unannounced Space
Size of Holding Areas (/8)
50
45
40
35
30
UnAnn
RIR
25
20
15
10
5
0
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
Modeling the Process
• Assume that the RIR efficiency in allocation
slowly declines, so that the amount of RIRheld 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
Modeling the Process - Exponential
IPv4 Model
IANA Pool Exhaustion 2022
RIR Pool Exhaustion 2024
200
IANA
RIR
BGP
IANA-P
RIR-P
BGP-P
RIR
LIR
150
100
50
0
Jan-00
Jan-05
Projections
Jan-10
Jan-15
Jan-20
Jan-25
Modeling the Process - Linear
IPv4 Model
IANA Pool Exhaustion 2030
RIR Pool Exhaustion 2037
200
IANA
RIR
BGP
IANA-P
RIR-P
BGP-P
RIR
LIR
150
100
50
0
Jan-00
Jan-05 Projections
Jan-10
Jan-15
Jan-20
Jan-25
Jan-30
Jan-35
Jan-40
Jan-45
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?
Questions?
gih@telstra.net
http://www.potaroo.net