bgp as number exhaustion - iepg.orgiepg.org/march2003/bgp as number exhaustion.pdf · the problem...
TRANSCRIPT
The Problem
• The 16 bit AS number field in BGP has 64,510 available values to use in the Internet’s public routing space
• Some 30,000 AS numbers have already been assigned by the RIRs
• This BGP protocol field will be exhausted at some point in the future
The Solution
• Use a 32 bit field for this value– draft-ietf-idr-as4bytes-06.txt describes how
– This is proposed for publication as an experimental RFC
The Issue
• At some point we will need to start testing various transition plans and vendor implementations, set up a new AS number registry, and commence deployment of these extended length protocol objects in BGP
When?• Before we run completely out of 16 bit AS
numbers!• Need to allow a lead time for testing,
deployment of 4-byte AS BGP implementations and development of appropriate transition arrangements– Allow 2 – 3 years to undertake this smoothly
• So we’d like to know when we have 3 years to go before we run out of AS numbers
When?
• A number of views can be used to make forward projections:– The growth of the number of announced AS’s in
the BGP routing table– The rate at which AS number blocks are passed
from IANA to the RIRs– The rate at which RIRs undertake assignments
of As’s to LIRs and end users
The BGP Routing TableAnnounced AS’s
BGP Table - AS Count
0
2000
4000
6000
8000
10000
12000
14000
16000
Sep-96 Sep-97 Sep-98 Sep-99 Sep-00 Sep-01 Sep-02 Sep-03
BGP Table
The BGP Routing TableGrowth Projections
0
10000
20000
30000
40000
50000
60000
Sep-96 Sep-99 Sep-02 Sep-05 Sep-08 Sep-11 Sep-14 Sep-17 Sep-20 Sep-23 Sep-26 Sep-29
pre-02 Exp TrendExponential TrendLinear TrendBGP Data
Feb 2013 Dec 2027Oct 2005
IANA AS block AllocationsIANA AS Allocations
0
5000
10000
15000
20000
25000
30000
35000
Jan-90 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03
IANA AS Allocations
From the IANA AS number Registry
IANA AS Allocation Projection
0
10000
20000
30000
40000
50000
60000
Jan-
90
Jan-
91
Jan-
92
Jan-
93
Jan-
94
Jan-
95
Jan-
96
Jan-
97
Jan-
98
Jan-
99
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
IANA AllocationsExp ProjectionLinear Projection
May 2007 Nov 2010
RIR Assignments
RIR Assignments
0
5000
10000
15000
20000
25000
Jan-90 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03
RIR Assignments
From the RIR stats reports
RIR Projection
0
10000
20000
30000
40000
50000
60000
Jan-
90
Jan-
91
Jan-
92
Jan-
93
Jan-
94
Jan-
95
Jan-
96
Jan-
97
Jan-
98
Jan-
99
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
Exp ProjectionLinear ProjectionRIR Assignments
Feb 2008 May 2013
Combining these views
0
10000
20000
30000
40000
50000
60000
90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14
IANAIANA EXPIANA LinearRIRRIR ExpRIR LinearBGPBGP exp 96-01BGP exp 02BGP Linear 02
Combined View + differences
0
5000
10000
15000
20000
25000
30000
35000
Jan-90 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03
IANARIR AssignedBGP AnnouncedNOT assignedNOT Announced
Observations
• RIRs operate with an allocation buffer of around 5,000 numbers
• 10,000 AS numbers (40% of the assigned AS numbers) are not announced in the BGP table.– Is this the result of old AS assignments falling
into disuse? – Or recent AS assignments being hoarded?– This pool creates uncertainty in 2 byte AS
number pool exhaustion predictions
Announced and Unannounced ASs
0
2000
4000
6000
8000
10000
12000
14000
16000
Oct
-96
Oct
-97
Oct
-98
Oct
-99
Oct
-00
Oct
-01
Oct
-02
AnnouncedUnannounced
Unannounced : Announced AS’s
Ratio Unann:Ann
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
Oct-96 Oct-97 Oct-98 Oct-99 Oct-00 Oct-01 Oct-02 Oct-03 Oct-04 Oct-05
Ratio Unann:Ann
Trend:unannounced : announced ratio
Ratio Unann:Ann
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25
Oct-96 Oct-97 Oct-98 Oct-99 Oct-00 Oct-01 Oct-02 Oct-03 Oct-04 Oct-05
Ratio Unann:Ann
Announced / Unannounced Distribution by Date
0
100
200
300
400
500
600
Jan-
90
May
-90
Sep
-90
Jan-
91
May
-91
Sep
-91
Jan-
92
May
-92
Sep
-92
Jan-
93
May
-93
Sep
-93
Jan-
94
May
-94
Sep
-94
Jan-
95
May
-95
Sep
-95
Jan-
96
May
-96
Sep
-96
Jan-
97
May
-97
Sep
-97
Jan-
98
May
-98
Sep
-98
Jan-
99
May
-99
Sep
-99
Jan-
00
May
-00
Sep
-00
Jan-
01
May
-01
Sep
-01
Jan-
02
May
-02
Sep
-02
Jan-
03
UnAnnouncedBGP Announced
Normalized Announced / Unannounced
0%
20%
40%
60%
80%
100%
Jan-
90
May
-90
Sep
-90
Jan-
91
May
-91
Sep
-91
Jan-
92
May
-92
Sep
-92
Jan-
93
May
-93
Sep
-93
Jan-
94
May
-94
Sep
-94
Jan-
95
May
-95
Sep
-95
Jan-
96
May
-96
Sep
-96
Jan-
97
May
-97
Sep
-97
Jan-
98
May
-98
Sep
-98
Jan-
99
May
-99
Sep
-99
Jan-
00
May
-00
Sep
-00
Jan-
01
May
-01
Sep
-01
Jan-
02
May
-02
Sep
-02
Jan-
03
UnAnnouncedBGP Announced
Distribution by AS Number Range
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271 281
UnassignedNOT AnnouncedAnnounced
Observations
• Low AS number ranges have the highest unannounced / announced ratios– Reclamation of unused AS numbers in the low
number ranges is likely to be a useful exercise
• Recent assignments show a 45% announcement utilization ratio for AS numbers– LIR staging point factors– Inadequate incentives to return if no
immediate requirement for deployment
Forecast 1 – AS Reclamation in effect
0
10000
20000
30000
40000
50000
60000
70000
1996
1997
1997
1998
1998
1999
1999
2000
2000
2001
2001
2002
2002
2003
2003
2004
2004
2005
2005
2006
2006
2007
2007
2008
2008
2009
2009
2010
2010
2011
IANARIRBGP ProjectionBGPUnassignedUnrouted
Forecast2 – No significant reclamation
-10000
0
10000
20000
30000
40000
50000
60000
70000
1996
1997
1997
1997
1998
1998
1998
1999
1999
1999
2000
2000
2000
2001
2001
2001
2002
2002
2002
2003
2003
2003
2004
2004
2004
2005
2005
2005
2006
2006
2006
2007
2007
2007
2008
2008
2008
2009
2009
IANARIRBGP ProjectionBGPUnassignedUnrouted
Current Forecast• The available AS number pool will exhaust in the
timeframe of 2009-2011 if current AS use trends continue
2009• no significant reclamation in old AS number space
• No coordinated effort to increase utilization density of AS numbers
2011• reclamation and increased deployment efficiency