Autonomous system detail  ·  US flag US

AS81

Announced

Operated by MCNC, US flag US.

Summary

// analyst note
The only large, actively transiting network in this block; analysts will see substantial legitimate R&E traffic from AS81. RPKI 109 IPv4 + 2 IPv6 valid, 0 invalid.
// security note
NEUTRAL/DATED: no notable AS-level abuse signal as of 2026-06-08; bgp.he.net notes 'announces bogons' (neutral).
IPv4 prefixes
134
~2.1M addresses
IPv6 prefixes
4
announced
Peer networks
46
7 up · 23 down
IANA block
1-1876
Assigned by ARIN
[ 01 ] — Context

About this ASN.

Updated  ·  Confidence: High  ·  3 sources  ·  How this page is checked

AS81 is a legacy allocation registered under ARIN to MCNC (OrgId MCNC-Z, Research Triangle Park / Durham, NC), carrying the handle "NCREN." RFC 1020 (1987) labeled it "TUCC-MCNC" (TUCC = Triangle Universities Computation Center), and it was later "CONCERT"; today AS81 operates NCREN — the North Carolina Research and Education Network — run by the non-profit MCNC, serving universities, K-12, and community colleges statewide. The ARIN RDAP RegDate is 1986-08-07 (record updated 2021-06-29). It is by far the largest and most active network in this cohort: as of June 2026 bgp.he.net reports 139 IPv4 and 3 IPv6 prefixes originated, 44 BGP peers, and ~2,126,592 IPv4 addresses, while bgp.tools lists 150 IPv4 / 3 IPv6 prefixes, 46 peers, 5 upstreams, and 36 downstreams (cone 37). Upstreams include Cogent (AS174), Lumen (AS3356), Charter (AS11426), AT&T (AS7018), and Zayo (AS6461). RPKI coverage is strong — 109 IPv4 and 2 IPv6 valid origins, 0 invalid. PeeringDB lists it as Educational/Research with an Open policy. For triage, analysts will see substantial legitimate R&E traffic from AS81. No notable AS-level abuse signal was found as of June 2026 (bgp.he.net notes it "announces bogons," stated neutrally).

Operator
MCNC (ARIN OrgId MCNC-Z, Research Triangle Park / Durham, NC) [Confirmed] — ARIN RDAP
Country / RIR
US, ARIN [Confirmed]
Allocated
ARIN RDAP RegDate 1986-08-07 (record updated 2021-06-29) [Confirmed]
Org status
active — largest in this cohort by customer cone

Security/abuse context (NEUTRAL, DATED)

no notable AS-level abuse signal as of 2026-06-08; bgp.he.net notes "announces bogons" (neutral); large eyeball/academic network — bgp.he.net

Network & routing

Network type
research / education (statewide R&E network) [Confirmed]
Size
139 IPv4 + 3 IPv6 prefixes (~2,126,592 IPv4 addrs) per bgp.he.net; 150 IPv4 / 3 IPv6, cone 37 per bgp.tools (2026-06)
Routing/peering
actively transiting; 44–46 peers, 5 upstreams (Cogent AS174, Lumen AS3356, Charter AS11426, AT&T AS7018, Zayo AS6461), 36 downstreams; PeeringDB Educational/Research, Open — bgp.he.net / bgp.tools
RPKI
109 IPv4 + 2 IPv6 valid origins, 0 invalid — bgp.he.net
Notable usage
[historical, RFC 1020] "TUCC-MCNC"; later "CONCERT." [current] operates NCREN — the North Carolina Research and Education Network (MCNC non-profit), serving universities, K-12, and community colleges statewide — mcnc.org
Related ASNs
none specifically confirmed for this profile
Analyst note
The only large, actively transiting network in this block; analysts will see substantial legitimate R&E traffic from AS81.
[ 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 prefixes134
  1. 204.84.0.0/15/15
  2. 128.109.0.0/16/16
  3. 152.10.0.0/16/16
  4. 152.11.0.0/16/16
  5. 152.12.0.0/16/16
  6. 152.18.0.0/16/16
  7. 152.20.0.0/16/16
  8. 152.21.0.0/16/16
  9. 152.22.0.0/16/16
  10. 152.26.0.0/16/16
  11. 152.27.0.0/16/16
  12. 152.28.0.0/16/16
  13. 152.29.0.0/16/16
  14. 152.30.0.0/16/16
  15. 152.4.0.0/16/16
  16. 152.40.0.0/16/16
  17. 152.45.0.0/16/16
  18. 152.46.0.0/16/16
  19. 152.47.0.0/16/16
  20. 152.48.0.0/16/16
  21. 152.49.0.0/16/16
  22. 152.54.0.0/16/16
  23. 152.6.0.0/16/16
  24. 152.60.0.0/16/16
  25. 152.8.0.0/16/16
  26. 152.9.0.0/16/16
  27. 198.85.0.0/16/16
  28. 198.86.0.0/16/16
  29. 152.32.0.0/18/18
  30. 152.38.0.0/18/18
  31. 152.42.64.0/18/18
  32. 204.85.192.0/18/18
  33. 152.38.160.0/19/19
  34. 152.38.224.0/19/19
  35. 152.38.64.0/19/19
  36. 206.211.64.0/19/19
  37. 152.38.192.0/20/20
  38. 152.38.208.0/20/20
  39. 152.54.0.0/20/20
  40. 204.84.80.0/20/20
  41. 152.22.32.0/21/21
  42. 152.22.40.0/21/21
  43. 152.22.48.0/21/21
  44. 152.22.64.0/21/21
  45. 152.22.72.0/21/21
  46. 152.22.80.0/21/21
  47. 152.46.16.0/21/21
  48. 204.84.112.0/21/21
  49. 152.30.92.0/22/22
  50. 152.46.252.0/22/22
  51. 198.86.244.0/22/22
  52. 192.101.22.0/23/23
  53. 192.154.76.0/23/23
  54. 152.26.16.0/24/24
  55. 152.26.208.0/24/24
  56. 152.26.209.0/24/24
  57. 152.26.210.0/24/24
  58. 152.26.211.0/24/24
  59. 152.26.212.0/24/24
  60. 152.26.213.0/24/24
  61. 152.26.44.0/24/24
  62. 152.26.60.0/24/24
  63. 152.26.69.0/24/24
  64. 152.27.12.0/24/24
  65. 152.28.1.0/24/24
  66. 152.30.10.0/24/24
  67. 152.30.92.0/24/24
  68. 152.38.17.0/24/24
  69. 152.38.18.0/24/24
  70. 152.45.1.0/24/24
  71. 152.45.10.0/24/24
  72. 152.45.11.0/24/24
  73. 152.45.15.0/24/24
  74. 152.45.2.0/24/24
  75. 152.45.20.0/24/24
  76. 152.45.3.0/24/24
  77. 152.45.4.0/24/24
  78. 152.45.5.0/24/24
  79. 152.45.6.0/24/24
  80. 152.45.8.0/24/24
  81. 152.45.9.0/24/24
  82. 152.46.1.0/24/24
  83. 152.46.12.0/24/24
  84. 152.46.13.0/24/24
  85. 152.46.14.0/24/24
  86. 152.46.15.0/24/24
  87. 152.46.2.0/24/24
  88. 152.46.24.0/24/24
  89. 152.46.25.0/24/24
  90. 152.46.26.0/24/24
  91. 152.46.27.0/24/24
  92. 152.46.28.0/24/24
  93. 152.46.29.0/24/24
  94. 152.46.3.0/24/24
  95. 152.46.30.0/24/24
  96. 152.46.31.0/24/24
  97. 152.46.32.0/24/24
  98. 152.46.33.0/24/24
  99. 152.46.34.0/24/24
  100. 152.46.35.0/24/24
  101. 152.46.36.0/24/24
  102. 152.46.37.0/24/24
  103. 152.46.38.0/24/24
  104. 152.46.39.0/24/24
  105. 152.46.4.0/24/24
  106. 152.46.42.0/24/24
  107. 152.46.43.0/24/24
  108. 152.46.44.0/24/24
  109. 152.46.45.0/24/24
  110. 152.46.47.0/24/24
  111. 152.46.48.0/24/24
  112. 152.46.5.0/24/24
  113. 152.46.6.0/24/24
  114. 152.46.7.0/24/24
  115. 152.46.8.0/24/24
  116. 152.46.9.0/24/24
  117. 152.60.4.0/24/24
  118. 185.83.159.0/24/24
  119. 192.101.21.0/24/24
  120. 192.101.22.0/24/24
  121. 192.101.24.0/24/24
  122. 192.137.210.0/24/24
  123. 192.154.33.0/24/24
  124. 192.154.43.0/24/24
  125. 192.154.48.0/24/24
  126. 192.154.55.0/24/24
  127. 192.154.58.0/24/24
  128. 192.154.60.0/24/24
  129. 192.154.61.0/24/24
  130. 192.154.66.0/24/24
  131. 192.154.95.0/24/24
  132. 192.189.244.0/24/24
  133. 204.84.120.0/24/24
  134. 206.107.110.0/24/24
// IPv6 prefixes4
  1. 2600:2700::/28/28
  2. 2610:28::/32/32
  3. 2602:f64d::/40/40
  4. 2602:f6b8::/40/40
[ 03 ] — Notable peers & upstreams

Who it talks to.

46 observed neighbours
// Notable connections32 of 46 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
AS174 Cogent Communications, LLC upstream
AS3356 Level 3 Parent, LLC (Lumen Technologies) upstream
AS6461 — upstream
AS7018 AT&T Enterprises, LLC upstream
AS11164 — upstream
AS11426 — upstream
AS11537 — upstream
AS6559 — downstream
AS10952 — downstream
AS11442 — downstream
AS13371 — downstream
AS13862 — downstream
AS18538 — downstream
AS19161 — downstream
AS19413 — downstream
AS19718 — downstream
AS20197 — peer
AS22862 — downstream
AS26407 — —
AS26741 — downstream
AS32417 — downstream
AS32711 — downstream
AS33401 — downstream
AS36850 — downstream
AS40245 — downstream
AS46255 — downstream
AS46794 — downstream
AS46963 — downstream
AS47098 — downstream
AS53384 — downstream
AS53785 — downstream
AS393824 — downstream
Neighbours observed via public BGP collectors; not a complete peering list.