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AS81MCNC

United StatesRegistryARINTypeCarrier

As of 22nd October 2026, AS81 (MCNC), a transit carrier registered in the United States with ARIN, originates 134 IPv4 prefixes covering 2.1M addresses and 4 IPv6 prefixes. By IPv4 address space that makes it the 267th-largest of the 79,655 networks we see originating IPv4, and the 65th-largest of 18,475 in the United States. It is seen behind 7 upstream networks, most often AS3356 (Lumen (Level 3)) and AS174 (Cogent Communications, LLC), and in front of 38 downstream networks. 78% of its announcements have a valid RPKI ROA, and none are RPKI-invalid. 99% of its routes reach at least 90% of full-feed peers.

At a glance

IPv4 prefixes

134

IPv6 prefixes

4

IPv4 addresses

2.1M

IPv6 /64s

73B

Upstream graph

The networks AS81 is seen behind, one and two hops out, drawn from real AS paths.

AS81Toward the internet core
Upstream graph for AS81: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS81MCNCThis networkAS174Cogent Communicat…AS3356Lumen (Level 3)AS7018AT&T Enterprises,…AS11426Charter Communica…AS11537Internet2AS151326DCConnect Communi…AS1299Arelion (fka. Tel…AS3549Lumen (fka. Globa…AS2914NTT America, Inc.AS7843Spectrum (Charter)AS398766TriCoLink, Inc.AS2153CENIC

Networks observed one and two hops upstream of AS81 in real AS paths. A thicker line means more vantage points saw that adjacency, so weight tracks how well attested it is — not how much traffic it carries. Adjacency is an observation; whether it is a transit purchase or a settlement-free peering is an inference, and is labelled as one wherever we show it.

Neighbouring networks

92

adjacent networks

Upstreams
78%
Peers
4751%
Downstreams
3841%

Networks carrying this one's traffic toward the rest of the internet.

Upstreams of AS81
NetworkCountryRelationshipPathsVantage pts
AS3356Lumen (Level 3)USPeer8,577140
AS174Cogent Communications, LLCUSPeer7,858135
AS11426Charter Communications IncUSPeer1,83670
AS7018AT&T Enterprises, LLCUSPeer61387
AS11537Internet2USPeer4102
AS11164Internet2 I2PXUSPeer37721
AS6461Zayo BandwidthUSPeer13740

Prefixes

All 138

The largest blocks AS81 originates, widest first.

Largest prefixes originated by AS81
PrefixAddressesVisibility
204.84.0.0/15131k76/77
128.109.0.0/1665.5k76/77
152.4.0.0/1665.5k77/77
152.6.0.0/1665.5k77/77
152.8.0.0/1665.5k76/77
152.9.0.0/1665.5k77/77
152.10.0.0/1665.5k76/77
152.11.0.0/1665.5k76/77
152.12.0.0/1665.5k77/77
152.18.0.0/1665.5k77/77

Routing health

How AS81's own announcements validate against RPKI and how far they propagate. The same measures for the whole routing table are on the routing table in numbers.

RPKI origin validation

  • Valid78.3%108
  • Invalid0.0%0
  • No ROA21.7%30

Propagation

  • Globally propagated90% of full-feed peers or more98.6%136
  • Partially propagated40% to 90%0.0%0
  • Seen by few peersUnder 40%1.4%2

Prefix sizes

IPv4 — 134 prefixes

IPv6 — 4 prefixes

  • /2868.7B × /6425.0%1
  • /324.3B × /6425.0%1
  • /4016.8M × /6450.0%2

Recent changes

Announcements that started or stopped since 22nd Sept 2026.

No announcement by AS81 started or stopped in this period.

Routing data derived from RouteViews MRT archives, BGPKIT relationship inference and public registry data.