subnet.im

AS103Northwestern University

United StatesRegistryARIN

As of 22nd October 2026, AS103 (Northwestern University), a network registered in the United States with ARIN, originates 22 IPv4 prefixes covering 150k addresses and 3 IPv6 prefixes. By IPv4 address space that makes it the 1,645th-largest of the 79,655 networks we see originating IPv4, and the 476th-largest of 18,475 in the United States. It is seen behind 10 upstream networks, most often AS2381 (WiscNet) and AS33491 (Comcast Cable Communications, LLC). None of its announcements have a valid RPKI ROA; 2 are RPKI-invalid. 92% of its routes reach at least 90% of full-feed peers.

At a glance

IPv4 prefixes

22

IPv6 prefixes

3

IPv4 addresses

150k

IPv6 /64s

16.8M

Upstream graph

The networks AS103 is seen behind, one and two hops out, drawn from real AS paths.

AS103Toward the internet core
Upstream graph for AS103: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS103Northwestern Univ…This networkAS174Cogent Communicat…AS2381WiscNetAS3356Lumen (Level 3)AS22335Metropolitan Rese…AS33491Comcast Cable Com…AS151326DCConnect Communi…AS1299Arelion (fka. Tel…AS6939Hurricane Electri…AS2914NTT America, Inc.AS3549Lumen (fka. Globa…AS11164Internet2 I2PXAS7922Comcast Cable Com…

Networks observed one and two hops upstream of AS103 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

23

adjacent networks

Upstreams
1043%
Peers
1357%
Downstreams
00%

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

Upstreams of AS103
NetworkCountryRelationshipPathsVantage pts
AS2381WiscNetUSPeer1,07886
AS33491Comcast Cable Communications, LLCUSPeer24316
AS3356Lumen (Level 3)USPeer22554
AS174Cogent Communications, LLCUSPeer10014
AS22335Metropolitan Research and Education NetworkUSPeer795
AS149433FM NetworksBDPeer2613
AS293ESnetUSPeer221
AS11164Internet2 I2PXUSPeer62
AS65502—Peer42
AS11537Internet2USPeer31

Prefixes

The largest blocks AS103 originates, widest first.

Largest prefixes originated by AS103
PrefixAddressesVisibility
129.105.0.0/1665.5k77/77
165.124.0.0/1732.8k77/77
199.74.64.0/1816.4k77/77
165.124.128.0/198.2k77/77
165.124.192.0/198.2k77/77
165.124.160.0/204.1k77/77
165.124.240.0/204.1k77/77
165.124.176.0/212k77/77
165.124.224.0/212k77/77
8.30.248.0/221k76/77

Routing health

How AS103'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

  • Valid0.0%0
  • Invalid8.0%2
  • No ROA92.0%23

Propagation

  • Globally propagated90% of full-feed peers or more92.0%23
  • Partially propagated40% to 90%0.0%0
  • Seen by few peersUnder 40%8.0%2

Prefix sizes

IPv4 — 22 prefixes

IPv6 — 3 prefixes

  • /418.4M × /6433.3%1
  • /424.2M × /6466.7%2

Recent changes

Announcements that started or stopped since 22nd Sept 2026.

  • Withdrawn165.124.17.0/246th Oct 2026
  • Withdrawn199.249.166.0/246th Oct 2026
  • Withdrawn199.249.167.0/246th Oct 2026
  • Withdrawn199.249.168.0/246th Oct 2026
  • Withdrawn199.249.169.0/246th Oct 2026

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