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ASN (Autonomous System Number) Assignments

IANA Autonomous System Number Allocation Status. View 16-bit and 32-bit ASN assignments by Regional Internet Registries.

Data source: IANA AS Numbers Registry (Key allocations shown)

Quick ASN Lookup

88
Total Ranges
83
Assigned
4
Reserved
65,536
Total ASNs
Showing 88 of 88 ranges
ASN RangeCountDescriptionRIRWHOISRDAPReferenceDate
01ReservedIANA--[RFC7607]-
1-18761,876Assigned by ARINARINwhois.arin.netLink--
1877-190125Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
1902-2042141Assigned by ARINARINwhois.arin.netLink--
20431Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
2044-20463Assigned by ARINARINwhois.arin.netLink--
20471Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
2048-210659Assigned by ARINARINwhois.arin.netLink--
2107-213630Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
2137-2584448Assigned by ARINARINwhois.arin.netLink--
2585-261430Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
2615-2772158Assigned by ARINARINwhois.arin.netLink--
2773-282250Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
2823-28297Assigned by ARINARINwhois.arin.netLink--
2830-287950Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
2880-3153274Assigned by ARINARINwhois.arin.netLink--
3154-3353200Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
3354-46071,254Assigned by ARINARINwhois.arin.netLink--
4608-4865258Assigned by APNICAPNICwhois.apnic.netLink--
4866-5376511Assigned by ARINARINwhois.arin.netLink--
5377-5631255Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
5632-66551,024Assigned by ARINARINwhois.arin.netLink--
6656-6911256Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
6912-7466555Assigned by ARINARINwhois.arin.netLink--
7467-7722256Assigned by APNICAPNICwhois.apnic.netLink--
7723-8191469Assigned by ARINARINwhois.arin.netLink--
8192-92151,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
9216-102391,024Assigned by APNICAPNICwhois.apnic.netLink--
10240-122872,048Assigned by ARINARINwhois.arin.netLink--
12288-133111,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
13312-153592,048Assigned by ARINARINwhois.arin.netLink--
15360-163831,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
16384-174071,024Assigned by ARINARINwhois.arin.netLink--
17408-184311,024Assigned by APNICAPNICwhois.apnic.netLink--
18432-204792,048Assigned by ARINARINwhois.arin.netLink--
20480-215031,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
21504-234551,952Assigned by ARINARINwhois.arin.netLink--
234561AS_TRANSIANA--[RFC6793]-
23457-2355195Assigned by ARINARINwhois.arin.netLink--
23552-245751,024Assigned by APNICAPNICwhois.apnic.netLink--
24576-255991,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink--
25600-266231,024Assigned by ARINARINwhois.arin.netLink-2002-03
26624-276471,024Assigned by ARINARINwhois.arin.netLink-2002-09
27648-286711,024Assigned by LACNICLACNICwhois.lacnic.netLink-2002-11
28672-296951,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2002-12
29696-307191,024Assigned by ARINARINwhois.arin.netLink-2003-03
30720-317431,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2003-09
31744-327671,024Assigned by ARINARINwhois.arin.netLink-2003-11
32768-337911,024Assigned by ARINARINwhois.arin.netLink-2004-05
33792-348151,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2004-06
34816-358391,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2005-02
35840-368631,024Assigned by ARINARINwhois.arin.netLink-2005-02
36864-378871,024Assigned by AFRINICAFRINICwhois.afrinic.netLink-2005-04
37888-389111,024Assigned by APNICAPNICwhois.apnic.netLink-2005-06
38912-399351,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2005-09
39936-409591,024Assigned by ARINARINwhois.arin.netLink-2006-03-29
40960-419831,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2006-04-13
41984-430071,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2006-11-17
43008-440311,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2007-04-23
44032-450551,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2007-09-14
45056-460791,024Assigned by APNICAPNICwhois.apnic.netLink-2007-10-11
46080-471031,024Assigned by ARINARINwhois.arin.netLink-2008-03-27
47104-481271,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2008-04-07
48128-491511,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2008-09-09
49152-501751,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2009-03-06
50176-511991,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2009-03-06
51200-522231,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2009-03-06
52224-532471,024Assigned by LACNICLACNICwhois.lacnic.netLink-2009-03-11
53248-542711,024Assigned by ARINARINwhois.arin.netLink-2009-04-21
54272-552951,024Assigned by ARINARINwhois.arin.netLink-2009-04-21
55296-563191,024Assigned by APNICAPNICwhois.apnic.netLink-2009-09-02
56320-573431,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2011-01-04
57344-583671,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2011-01-04
58368-593911,024Assigned by APNICAPNICwhois.apnic.netLink-2011-08-09
59392-604151,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2012-03-21
60416-614391,024Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2012-03-21
61440-61951512Assigned by LACNICLACNICwhois.lacnic.netLink-2013-06-11
61952-62463512Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2013-09-09
62464-634871,024Assigned by ARINARINwhois.arin.netLink-2013-05-30
63488-63999512Assigned by APNICAPNICwhois.apnic.netLink-2013-09-11
64000-6409899Assigned by APNICAPNICwhois.apnic.netLink-2014-09-02
64099-6419799Assigned by LACNICLACNICwhois.lacnic.netLink-2014-09-05
64198-6429699Assigned by ARINARINwhois.arin.netLink-2015-04-29
64297-6439599Assigned by APNICAPNICwhois.apnic.netLink-2016-05-25
64396-64495100Assigned by RIPE NCCRIPE NCCwhois.ripe.netLink-2016-07-29
64496-6451116Reserved for use in documentation and sample codeIANA--[RFC5398]2008-12-03
64512-655341,023Reserved for Private UseIANA--[RFC6996]-
655351ReservedIANA--[RFC7300]-

About Autonomous System Numbers

An Autonomous System Number (ASN) is a unique identifier assigned to an autonomous system for use in BGP routing. An autonomous system is a collection of IP networks and routers under the control of one entity that presents a common routing policy.

ASN Types

  • • 16-bit ASN: Range from 0 to 65,535 (original format)
  • • 32-bit ASN: Range from 0 to 4,294,967,295 (expanded format)
  • • The 32-bit space includes the 16-bit range (0-65535 maps to 16-bit ASNs)

Special Purpose ASNs

16-bit Special ASNs:
  • • AS0: Reserved (RFC 7607)
  • • AS23456: AS_TRANS (BGP transition, RFC 6793)
  • • AS64496-AS64511: Documentation (RFC 5398)
  • • AS64512-AS65534: Private Use (RFC 6996)
  • • AS65535: Reserved (RFC 7300)
32-bit Special ASNs:
  • • AS65536-AS65551: Documentation (RFC 5398)
  • • AS4200000000-AS4294967294: Private Use (RFC 6996)
  • • AS4294967295: Reserved (RFC 7300)

Regional Internet Registries

Five RIRs manage ASN allocation globally:

  • • ARIN: North America
  • • RIPE NCC: Europe, Middle East, Central Asia
  • • APNIC: Asia-Pacific
  • • LACNIC: Latin America and Caribbean
  • • AFRINIC: Africa

Common Use Cases

  • • Public ASN: Required for BGP routing with multiple external networks
  • • Private ASN: Internal routing within organizations
  • • IXP: Internet Exchange Points use public ASNs
  • • Multi-homing: Organizations with multiple ISP connections

BGP and ASN

Border Gateway Protocol (BGP) uses ASNs to identify autonomous systems, prevent routing loops, and implement routing policies. The AS_PATH attribute in BGP shows the sequence of ASNs a route has traversed.

For the most current information, visit IANA AS Numbers Registry

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