Autonomous system detail  ·  US flag US

AS109

Announced

Operated by Cisco Systems, Inc., US flag US.

Summary

// analyst note
A clean, well-managed enterprise/vendor network; encountering it indicates Cisco corporate infrastructure.
// security note
NEUTRAL/DATED: no notable public abuse signal found as of 2026-06-07; strong routing hygiene; abuse via Cisco CSIRT (CISCO6-ARIN).
IPv4 prefixes
94
~1.6M addresses
IPv6 prefixes
44
announced
Peer networks
18
17 up · 0 down
IANA block
1-1876
Assigned by ARIN
[ 01 ] — Context

About this ASN.

Updated  ·  Confidence: High  ·  4 sources  ·  How this page is checked

AS109 is Cisco Systems' principal corporate ASN, a 1987 allocation registered under ARIN. It is a large, well-run enterprise network: it originates about 93 IPv4 prefixes and 43–44 IPv6 prefixes (~1.15 million IPv4 addresses), is present at roughly nine Internet exchanges, and is well-connected to major carriers including Lumen, PCCW, Telstra International, Arelion, TATA, and Hurricane Electric. Routing hygiene is strong — Hurricane Electric shows 134 valid originations and zero invalid. For triage this is a clean vendor/enterprise network; encountering it indicates Cisco corporate infrastructure, with abuse handled through Cisco's CSIRT. The AS-CISCO IRR as-set lists only AS109 as a member, and while Cisco operates additional ASNs (largely from acquisitions), AS109 is the flagship; the sometimes-cited "AS1351" could not be verified as a core Cisco ASN and is not asserted here. No notable public abuse signal was found as of June 2026.

Operator
Cisco Systems, Inc. (ARIN; org migrated to OrgId CS-2831, Wilmington, DE, registered 2023-06-07, alongside legacy CISCOS-2, San Jose, CA) [Confirmed] — ARIN RDAP
Country / RIR
US, ARIN [Confirmed]
Allocated
ASN RegDate 1987-05-06; updated 2023-09-12 [Confirmed] — ARIN
Org status
active (Cisco Systems, Inc.)

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-07; strong routing hygiene; abuse via Cisco CSIRT (CISCO6-ARIN) — bgpview.io

Network & routing

Network type
enterprise / vendor [Confirmed]
Size
~93 IPv4 prefixes, ~43–44 IPv6 (~1,149,696 IPv4 addrs) — bgp.he.net (2026-06)
Routing/peering
~9 IXes; upstreams incl. AS3356 (Lumen), AS3491 (PCCW), AS4637 (Telstra Intl), AS1299 (Arelion), AS4755 (TATA), AS6939 (HE); RPKI strong — HE shows 134 valid, 0 invalid — bgp.he.net
Notable usage
Cisco Systems' principal corporate ASN; large, well-connected enterprise network — cisco.com
Related ASNs
AS-CISCO IRR as-set lists only AS109; Cisco operates additional (mostly acquisition-derived) ASNs, but AS109 is the flagship. "AS1351" could NOT be verified as a core Cisco ASN [Unknown — not asserted]
Analyst note
A clean, well-managed enterprise/vendor network; encountering it indicates Cisco corporate infrastructure.
[ 02 ] — Announced prefixes

What this network routes.

138 prefixes total · as observed by RouteViews at 2026-09-20 · one collector view, not a global census
// IPv4 prefixes94
  1. 171.68.0.0/14/14
  2. 173.36.0.0/14/14
  3. 128.107.0.0/16/16
  4. 144.254.0.0/16/16
  5. 161.44.0.0/16/16
  6. 64.100.0.0/16/16
  7. 64.102.0.0/16/16
  8. 64.103.0.0/16/16
  9. 64.104.0.0/16/16
  10. 72.163.0.0/16/16
  11. 173.36.0.0/17/17
  12. 173.38.0.0/17/17
  13. 173.38.128.0/17/17
  14. 64.103.0.0/17/17
  15. 64.103.128.0/17/17
  16. 173.37.192.0/18/18
  17. 173.37.64.0/18/18
  18. 173.39.0.0/18/18
  19. 64.101.0.0/18/18
  20. 64.101.128.0/18/18
  21. 64.101.64.0/18/18
  22. 64.104.0.0/18/18
  23. 64.104.192.0/18/18
  24. 72.163.0.0/18/18
  25. 72.163.128.0/18/18
  26. 173.37.128.0/19/19
  27. 173.37.160.0/19/19
  28. 173.39.128.0/19/19
  29. 173.39.160.0/19/19
  30. 173.39.64.0/19/19
  31. 173.39.96.0/19/19
  32. 192.133.192.0/19/19
  33. 216.128.32.0/19/19
  34. 64.101.192.0/19/19
  35. 64.101.224.0/19/19
  36. 64.101.96.0/19/19
  37. 64.103.64.0/19/19
  38. 64.104.128.0/19/19
  39. 64.104.160.0/19/19
  40. 64.104.64.0/19/19
  41. 64.104.96.0/19/19
  42. 72.163.192.0/19/19
  43. 72.163.224.0/19/19
  44. 72.163.96.0/19/19
  45. 173.37.0.0/20/20
  46. 173.37.16.0/20/20
  47. 173.39.192.0/20/20
  48. 192.133.224.0/20/20
  49. 64.103.96.0/20/20
  50. 66.187.208.0/20/20
  51. 72.163.64.0/20/20
  52. 72.163.80.0/20/20
  53. 12.19.88.0/21/21
  54. 173.39.144.0/21/21
  55. 173.39.152.0/21/21
  56. 198.135.0.0/21/21
  57. 64.103.40.0/21/21
  58. 64.103.48.0/21/21
  59. 103.60.32.0/22/22
  60. 111.223.8.0/22/22
  61. 12.159.148.0/22/22
  62. 192.118.76.0/22/22
  63. 192.133.240.0/22/22
  64. 72.163.248.0/22/22
  65. 12.5.186.0/23/23
  66. 128.107.0.0/23/23
  67. 128.107.10.0/23/23
  68. 128.107.12.0/23/23
  69. 128.107.14.0/23/23
  70. 128.107.18.0/23/23
  71. 128.107.2.0/23/23
  72. 128.107.20.0/23/23
  73. 128.107.22.0/23/23
  74. 128.107.24.0/23/23
  75. 128.107.38.0/23/23
  76. 128.107.4.0/23/23
  77. 128.107.40.0/23/23
  78. 128.107.54.0/23/23
  79. 128.107.6.0/23/23
  80. 128.107.8.0/23/23
  81. 173.39.200.0/23/23
  82. 192.118.78.0/23/23
  83. 204.69.198.0/23/23
  84. 64.104.204.0/23/23
  85. 64.104.206.0/23/23
  86. 72.163.240.0/23/23
  87. 173.37.145.0/24/24
  88. 192.135.250.0/24/24
  89. 198.133.219.0/24/24
  90. 204.69.200.0/24/24
  91. 64.102.249.0/24/24
  92. 64.104.124.0/24/24
  93. 72.163.4.0/24/24
  94. 72.163.7.0/24/24
// IPv6 prefixes44
  1. 2001:420::/32/32
  2. 2001:420:2000::/35/35
  3. 2001:420:4000::/36/36
  4. 2001:420:5000::/39/39
  5. 2001:420:5200::/39/39
  6. 2001:420:5400::/39/39
  7. 2001:420:5600::/39/39
  8. 2001:420:5800::/39/39
  9. 2001:420:5a00::/39/39
  10. 2001:420:5c00::/39/39
  11. 2001:420:5e00::/39/39
  12. 2001:420:1000::/40/40
  13. 2001:420:4000::/40/40
  14. 2001:420:5500::/40/40
  15. 2001:420:1100::/41/41
  16. 2001:420:1180::/41/41
  17. 2001:420:1200::/41/41
  18. 2001:420:4480::/45/45
  19. 2001:420:c110::/45/45
  20. 2001:420:c0c0::/46/46
  21. 2001:420:c0c4::/46/46
  22. 2001:420:c0cc::/46/46
  23. 2001:420:c0d0::/46/46
  24. 2001:420:c0d4::/46/46
  25. 2001:420:c0d8::/46/46
  26. 2001:420:c0dc::/46/46
  27. 2001:420:c0e0::/46/46
  28. 2001:420:c0ec::/46/46
  29. 2001:420:c0f8::/46/46
  30. 2001:420:c130::/46/46
  31. 2001:420:c134::/46/46
  32. 2001:420:c138::/46/46
  33. 2001:420:c128::/47/47
  34. 2001:420:88::/48/48
  35. 2001:420:89::/48/48
  36. 2001:420:8a::/48/48
  37. 2001:420:8b::/48/48
  38. 2001:420:8c::/48/48
  39. 2001:420:8d::/48/48
  40. 2001:420:8e::/48/48
  41. 2001:420:8f::/48/48
  42. 2001:420:91::/48/48
  43. 2001:420:92::/48/48
  44. 2001:420:93::/48/48
[ 03 ] — Notable peers & upstreams

Who it talks to.

18 observed neighbours
// Notable connections18 of 18 observed

Neighbours observed by RouteViews at 2026-09-20, lowest ASN first. Relationships are inferences from the CAIDA AS Relationships Dataset, 2026-08-01, and establish no commercial arrangement; a dash means the inference did not resolve.

ASNOperatorRole
AS701 Verizon Business (MCI Communications Services) upstream
AS1221 — upstream
AS1299 Arelion Sweden AB upstream
AS1680 — upstream
AS2764 — upstream
AS3356 Level 3 Parent, LLC (Lumen Technologies) upstream
AS3491 PCCW Global (HK) Limited upstream
AS4637 — upstream
AS4657 — upstream
AS4755 — upstream
AS4812 — upstream
AS6939 Hurricane Electric LLC upstream
AS7018 AT&T Enterprises, LLC upstream
AS7473 — upstream
AS8551 — upstream
AS9498 — upstream
AS17621 — upstream
AS11164 — peer
Neighbours observed via public BGP collectors; not a complete peering list.