521:(CDNs) exchange Internet traffic between their networks (autonomous systems). These are often groups of local ISPs that band together to exchange data by splitting the costs of a local networking hub, avoiding the higher costs (and bandwidth charges) of a Transit AS. IXP ASNs are usually transparent. By having presence in an IXP, ASes shorten the transit path to other participating ASes, thereby reducing
177:(RIRs). The appropriate RIR then assigns ASNs to entities within its designated area from the block assigned by IANA. Entities wishing to receive an ASN must complete the application process of their RIR, LIR or upstream service provider and be approved before being assigned an ASN. Current IANA ASN assignments to RIRs can be found on the IANA website. RIRs, as part of
485:: An AS that maintains connections to more than one other AS. This allows the AS to remain connected to the Internet in the event of a complete failure of one of their connections. However, unlike a transit AS, this type of AS would not allow traffic from one AS to pass through on its way to another AS.
156:
The first and last ASNs of the original 16-bit integers (0 and 65,535) and the last ASN of the 32-bit numbers (4,294,967,295) are reserved and should not be used by operators; AS0 is used by all five RIRs to invalidate unallocated space. ASNs 64,496 to 64,511 of the original 16-bit range and 65,536
558:
AS-SETs are often used to simplify management of published routing policies. A routing policy is published in the IRR using "import" and "export" (or the newer "mp-import" and "mp-export") attributes, which each contain the source or destination AS number and the AS number imported or exported.
152:
are exactly the old 16-bit AS numbers. The special 16-bit ASN 23456 ("AS_TRANS") was assigned by IANA as a placeholder for 32-bit ASN values for the case when 32-bit-ASN capable routers ("new BGP speakers") send BGP messages to routers with older BGP software ("old BGP speakers") which do not
160:
The number of unique autonomous networks in the routing system of the
Internet exceeded 5,000 in 1999, 30,000 in late 2008, 35,000 in mid-2010, 42,000 in late 2012, 54,000 in mid-2016 and 60,000 in early 2018. The number of allocated ASNs exceeded 100,000 as of March 2021.
538:
Autonomous systems can be included in one or more AS-SETs, for example AS-SET of RIPE NCC "AS-12655" has AS1, AS2 and AS3 as its members, but AS1 is also included in other sets in ARIN (AS-INCAPSULA) and APNIC (AS-IMCL). Another AS-SET sources can be RADB, LEVEL3
112:(ISP) or a very large organization with independent connections to multiple networks, that adhered to a single and clearly defined routing policy. In March 1996, the newer definition came into use because multiple organizations can run
120:
that connects all those organizations to the
Internet. Even though there may be multiple autonomous systems supported by the ISP, the Internet only sees the routing policy of the ISP. That ISP must have an officially registered ASN.
554:
AS-SET names usually start with "AS-", but can also have a hierarchical name. For example, the administrator of AS 64500 may create an AS-SET called "AS64500:AS-UPSTREAMS", to avoid conflict with other similarly named AS-SETs.
1299:
509:: An AS that acts as a router between two ASes is called a transit. Since not all ASes are directly connected with every other AS, a transit AS carries data traffic between one AS to another AS to which it has links.
80:
prefixes under the control of one or more network operators on behalf of a single administrative entity or domain, that presents a common and clearly defined routing policy to the
Internet. Each AS is assigned an
157:
to 65,551 of the 32-bit range are reserved for use in documentation. ASNs 64,512 to 65,534 of the original 16-bit AS range, and 4,200,000,000 to 4,294,967,294 of the 32-bit range are reserved for
Private Use.
493:: An AS that is connected to only one other AS. This may be an apparent waste of an AS number if the network's routing policy is the same as its upstream AS's. However, the stub AS may have
1166:
1417:
105:(IANA). The IANA also maintains a registry of ASNs which are reserved for private use (and should therefore not be announced to the global Internet).
1269:
132:(RIRs). These numbers are written preferably as simple integers, in a notation referred to as "asplain", ranging from 0 to 4,294,967,295 (
170:
125:
102:
559:
Instead of single AS numbers, AS-SETs can be referenced in these attributes, which simplifies management of complex routing policies.
270:
847:
Validation of Route
Origination Using the Resource Certificate Public Key Infrastructure (PKI) and Route Origin Authorizations (ROAs)
1232:
819:
750:
703:
656:
618:
1507:
124:
Until 2007, AS numbers were defined as 16-bit integers, which allowed for a maximum of 65,536 assignments. Since then, the
1091:
178:
38:
1291:
476:
Autonomous systems (AS) can be grouped into four categories, depending on their connectivity and operating policy.
174:
129:
98:
94:
579:
548:
109:
73:
518:
1449:
590:
568:
513:
113:
90:
1261:
1053:
1007:
949:
911:
865:
802:
764:
717:
670:
632:
498:
576:β a hotline communications system between the network operations centers of major Autonomous Systems
1487:
547:) and also ARIN has ARIN-NONAUTH source of AS-SETs. AS-SETs are created by network operators in an
182:
1265:
544:
501:. Specific examples include private interconnections in the financial and transportation sectors.
1183:
1208:
1160:
1045:
903:
1035:
997:
939:
893:
855:
792:
754:
726:
707:
679:
660:
622:
551:(IRR), like other route objects, and can be included in other AS-SETs and even form cycles.
526:
505:
276:
17:
1115:
612:
522:
540:
1501:
1369:
823:
489:
1141:
587:β a freely available web-based database of networks that are interested in peering
614:
Guidelines for creation, selection, and registration of an
Autonomous System (AS)
1056:
1025:
1010:
991:
952:
929:
914:
883:
868:
845:
805:
782:
767:
744:
730:
720:
697:
683:
673:
650:
635:
481:
463:
446:
403:
399:
382:
365:
361:
344:
314:
284:
280:
133:
1295:
136:
0xFFFF FFFF). Or, alternatively, in the form called "asdot+" which looks like
1049:
907:
214:
108:
Originally, the definition required control by a single entity, typically an
1459:
1393:
584:
232:
966:
1477:
1321:
820:"Using AS 23456: How BGP Uses Conversion or Truncation For Compatibility"
573:
201:
1345:
1468:
Robtex: Various kinds of research of IP numbers, Domain names, ASN, etc
494:
223:
210:
101:(RIRs), which in turn receive blocks of ASNs for reassignment from the
77:
1482:
1071:
1040:
1002:
944:
898:
860:
797:
759:
712:
665:
627:
228:
196:
205:
192:
1233:"Policy prop-132 (AS0 for unallocated space) deployed in service"
1092:"World - Autonomous System Number statistics - Sorted by number"
1031:
935:
889:
851:
788:
219:
1492:
993:
Autonomous System (AS) Number
Reservation for Documentation Use
1472:
784:
BGP Support for Four-Octet
Autonomous System (AS) Number Space
497:
with other autonomous systems that is not reflected in public
117:
1462:
517:(IX or IXP): A physical infrastructure through which ISPs or
1473:
astraceroute, an AS traceroute utility (part of netsniff-ng)
1467:
1440:
928:
W. Kumari; R. Bush; H. Schiller; K. Patel (August 2015).
93:(BGP) routing. Autonomous System Numbers are assigned to
1446:
746:
1262:"Understanding Autonomous Systems: Routing and Peering"
42:
1493:
Lookin'STAT Graph: number of
Autonomous systems online
1418:"Descriptions of Primary Objects - RIPE Database Docs"
97:(LIRs) and end-user organizations by their respective
1454:
243:
A complete table of available 16-bit and 32-bit ASN:
1142:"Autonomous System (AS) Number Assignment Policies"
743:Huston, Geoff; Michaelson, George (December 2008).
1027:Autonomous System (AS) Reservation for Private Use
885:Reservation of Last Autonomous System (AS) Numbers
395:Reserved for use in documentation and sample code
340:Reserved for use in documentation and sample code
1255:
1253:
188:There are other sources for more specific data:
128:has begun to also assign 32-bit AS numbers to
1209:"Revocation of Internet Resources allocation"
8:
1165:: CS1 maint: numeric names: authors list (
1070:Bates, Tony; Smith, Philip; Huston, Geoff.
611:Hawkinson, John; Bates, Tony (March 1996).
26:
844:G. Huston; G. Michaelson (February 2012).
699:BGP Support for Four-octet AS Number Space
215:https://ftp.afrinic.net/pub/stats/afrinic/
1488:Partial List of Autonomous system numbers
1292:"Glossary: Internet exchange point (IXP)"
1039:
1001:
943:
897:
859:
796:
758:
711:
664:
626:
181:, can revoke AS numbers as part of their
245:
233:https://ftp.lacnic.net/pub/stats/lacnic/
148:are 16-bit numbers. Numbers of the form
32:This is an accepted version of this page
1178:
1176:
1096:Regional Internet Registries Statistics
696:Vohra, Quaizar; Chen, Enke (May 2007).
649:Rekhter, Yakov; Li, Tony (March 1995).
603:
28:
1158:
169:AS numbers are assigned in blocks by
7:
1443:β Internet Measurements and Analysis
1260:Krzyzanowski, Paul (21 March 2016).
224:https://ftp.arin.net/pub/stats/arin/
781:Q. Vohra; E. Chen (December 2012).
652:A Border Gateway Protocol 4 (BGP-4)
171:Internet Assigned Numbers Authority
103:Internet Assigned Numbers Authority
1302:from the original on 30 March 2022
1268:, Department of Computer Science.
882:J. Haas; J. Mitchell (July 2014).
197:https://ftp.apnic.net/stats/apnic/
57:
1272:from the original on 3 March 2022
1184:"Autonomous System (AS) Numbers"
1146:RIPE Network Coordination Centre
1140:Mar 2017, Publication date: 14.
310:Reserved for AS Pool Transition
206:https://ftp.ripe.net/ripe/stats/
153:understand the new 32-bit ASNs.
931:Codification of AS 0 Processing
273:unallocated space invalidation
116:using private AS numbers to an
72:) is a collection of connected
1483:CIDR and ASN assignment report
1455:Hurricane Electric BGP Toolkit
1:
822:. 2008-07-21. Archived from
175:regional Internet registries
130:regional Internet registries
99:Regional Internet Registries
18:Autonomous System (Internet)
990:G. Huston (December 2008).
1524:
1463:https://www.peeringdb.com/
1024:J. Mitchell (July 2013).
996:. Network Working Group.
580:Internet Routing Registry
549:Internet Routing Registry
519:content delivery networks
442:Reserved for private use
357:Reserved for private use
110:Internet service provider
95:Local Internet Registries
1394:"IDIDB - ΠΠ±ΡΠ΅ΠΊΡΡ AS-SET"
83:autonomous system number
39:latest accepted revision
1322:"AS-12655 - bgp.he.net"
971:irrexplorer.dashcare.nl
591:Routing Assets Database
569:Administrative distance
514:Internet Exchange Point
91:Border Gateway Protocol
61:Internet routing system
436:4200000000β4294967294
1508:Internet architecture
1374:irrexplorer.nlnog.net
1350:irrexplorer.nlnog.net
1116:"How to setup a LIR"
429:Public 32-bit ASNs
183:Internet governance
29:Page version status
1266:Rutgers University
545:Lumen Technologies
499:route-view servers
423:131072β4199999999
35:
469:
468:
74:Internet Protocol
66:autonomous system
16:(Redirected from
1515:
1428:
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1199:
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1128:
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1067:
1061:
1060:
1043:
1041:10.17487/RFC6996
1021:
1015:
1014:
1005:
1003:10.17487/RFC5398
987:
981:
980:
978:
977:
963:
957:
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947:
945:10.17487/RFC7607
925:
919:
918:
901:
899:10.17487/RFC7300
879:
873:
872:
863:
861:10.17487/RFC6483
841:
835:
834:
832:
831:
816:
810:
809:
800:
798:10.17487/RFC6793
778:
772:
771:
762:
760:10.17487/RFC5396
740:
734:
724:
715:
713:10.17487/RFC4893
693:
687:
677:
668:
666:10.17487/RFC1771
646:
640:
639:
630:
628:10.17487/RFC1930
608:
527:round-trip delay
246:
21:
1523:
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1497:
1437:
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1191:
1182:
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1174:
1157:
1150:
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1139:
1138:
1134:
1124:
1122:
1120:www.afrinic.net
1114:
1113:
1109:
1100:
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1089:
1085:
1076:
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1069:
1068:
1064:
1023:
1022:
1018:
989:
988:
984:
975:
973:
965:
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960:
927:
926:
922:
881:
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829:
827:
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813:
780:
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775:
742:
741:
737:
695:
694:
690:
648:
647:
643:
621:. sec. 3.
610:
609:
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565:
536:
523:network latency
474:
241:
167:
62:
55:
54:
53:
52:
51:
50:
34:
22:
15:
12:
11:
5:
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1490:
1485:
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1465:
1457:
1452:
1444:
1436:
1435:External links
1433:
1430:
1429:
1409:
1385:
1370:"IRR explorer"
1361:
1346:"IRR explorer"
1337:
1313:
1283:
1249:
1224:
1213:www.lacnic.net
1200:
1172:
1132:
1107:
1083:
1062:
1016:
982:
967:"IRR explorer"
958:
920:
874:
836:
811:
773:
735:
725:(obsoleted by
688:
678:(obsoleted by
641:
602:
601:
599:
596:
595:
594:
588:
582:
577:
571:
564:
561:
541:tier 1 network
535:
532:
531:
530:
525:and improving
510:
502:
486:
473:
470:
467:
466:
460:
457:
454:
450:
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443:
440:
437:
433:
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427:
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396:
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379:
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260:
259:
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217:
208:
199:
166:
163:
89:), for use in
60:
56:
36:
30:
27:
25:
24:
23:
14:
13:
10:
9:
6:
4:
3:
2:
1520:
1509:
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1494:
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1471:
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1461:
1458:
1456:
1453:
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1419:
1413:
1410:
1399:
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1389:
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1375:
1371:
1365:
1362:
1351:
1347:
1341:
1338:
1327:
1323:
1317:
1314:
1301:
1297:
1293:
1287:
1284:
1271:
1267:
1263:
1256:
1254:
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1238:
1234:
1228:
1225:
1214:
1210:
1204:
1201:
1189:
1185:
1179:
1177:
1173:
1168:
1162:
1147:
1143:
1136:
1133:
1121:
1117:
1111:
1108:
1097:
1093:
1087:
1084:
1073:
1072:"CIDR report"
1066:
1063:
1058:
1055:
1052:. BCP 6.
1051:
1047:
1042:
1037:
1033:
1029:
1028:
1020:
1017:
1012:
1009:
1004:
999:
995:
994:
986:
983:
972:
968:
962:
959:
954:
951:
946:
941:
937:
933:
932:
924:
921:
916:
913:
910:. BCP 6.
909:
905:
900:
895:
891:
887:
886:
878:
875:
870:
867:
862:
857:
853:
849:
848:
840:
837:
826:on 2016-10-29
825:
821:
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804:
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769:
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629:
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583:
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560:
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550:
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533:
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516:
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438:
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428:
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418:
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412:
410:65552β131071
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312:
309:
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302:
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278:
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272:
269:Reserved for
268:
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261:
257:
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234:
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96:
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88:
84:
79:
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71:
67:
59:
48:
44:
40:
33:
19:
1421:. Retrieved
1412:
1401:. Retrieved
1398:www.ididb.ru
1397:
1388:
1377:. Retrieved
1373:
1364:
1353:. Retrieved
1349:
1340:
1329:. Retrieved
1325:
1316:
1304:. Retrieved
1286:
1274:. Retrieved
1241:. Retrieved
1239:. 2020-09-02
1236:
1227:
1216:. Retrieved
1212:
1203:
1192:. Retrieved
1190:. 2018-12-07
1187:
1149:. Retrieved
1145:
1135:
1123:. Retrieved
1119:
1110:
1099:. Retrieved
1095:
1086:
1075:. Retrieved
1065:
1026:
1019:
992:
985:
974:. Retrieved
970:
961:
930:
923:
884:
877:
846:
839:
828:. Retrieved
824:the original
814:
783:
776:
745:
738:
698:
691:
651:
644:
613:
606:
557:
553:
537:
512:
504:
488:
480:
475:
389:65536β65551
351:64512β65534
334:64496β64511
327:Public ASNs
321:23457β64495
297:Public ASNs
255:Description
242:
187:
168:
159:
155:
149:
145:
141:
137:
123:
107:
86:
82:
69:
65:
63:
58:
46:
37:This is the
31:
543:now called
453:4294967295
402:, RFC
364:, RFC
283:, RFC
185:abilities.
134:hexadecimal
47:14 May 2024
1423:2023-04-05
1403:2021-10-24
1379:2022-01-30
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