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AS4University of Southern California

United StatesRegistryARIN

As of 23rd October 2026, AS4 (University of Southern California), a network registered in the United States with ARIN, originates 44 IPv4 prefixes covering 70.1k addresses and 9 IPv6 prefixes. By IPv4 address space that makes it the 3,097th-largest of the 79,652 networks we see originating IPv4, and the 1,014th-largest of 18,475 in the United States. It is seen behind 9 upstream networks, most often AS226 (Los Nettos) and AS567 (Los Nettos), and in front of 2 downstream networks. 2% of its announcements have a valid RPKI ROA, and none are RPKI-invalid. 79% of its routes reach at least 90% of full-feed peers, and 6 prefixes are also originated by another network.

At a glance

IPv4 prefixes

44

IPv6 prefixes

9

IPv4 addresses

70.1k

IPv6 /64s

12.9B

Upstream graph

The networks AS4 is seen behind, one and two hops out, drawn from real AS paths.

AS4Toward the internet core
Upstream graph for AS4: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS4University of Sou…This networkAS174Cogent Communicat…AS226Los NettosAS567Los NettosAS10886University of Mar…AS266625WCA TELECOMAS151326DCConnect Communi…AS2914NTT America, Inc.AS1299Arelion (fka. Tel…AS2152CENIC - CalRENAS2153CENICAS6461Zayo BandwidthAS61642Nexnett Brasil Te…

Networks observed one and two hops upstream of AS4 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

25

adjacent networks

Upstreams
936%
Peers
1456%
Downstreams
28%

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

Upstreams of AS4
NetworkCountryRelationshipPathsVantage pts
AS226Los NettosUSPeer2,319108
AS567Los NettosUSPeer84969
AS174Cogent Communications, LLCUSPeer7676
AS10886University of MarylandUSPeer7676
AS266625WCA TELECOMBRPeer4747
AS266306CENTRALNETT TELECOMBRPeer2121
AS400215Sambanova Systems, Inc.USPeer104
AS37358BitCoZAPeer54
AS30844Liquid Intelligent Technologies GBPeer22

Prefixes

All 53

The largest blocks AS4 originates, widest first.

Largest prefixes originated by AS4
PrefixAddressesVisibility
128.9.192.0/1816.4k77/77
128.9.0.0/204.1k77/77
128.9.32.0/204.1k77/77
128.9.48.0/204.1k76/77
128.9.64.0/204.1k77/77
128.9.80.0/204.1k77/77
128.9.96.0/204.1k77/77
128.9.112.0/204.1k77/77
128.9.128.0/204.1k77/77
128.9.144.0/204.1k77/77

Routing health

How AS4'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

  • Valid1.9%1
  • Invalid0.0%0
  • No ROA98.1%52

Propagation

  • Globally propagated90% of full-feed peers or more79.2%42
  • Partially propagated40% to 90%1.9%1
  • Seen by few peersUnder 40%18.9%10

Prefix sizes

IPv4 — 44 prefixes

IPv6 — 9 prefixes

  • /324.3B × /6433.3%3
  • /4865.5k × /6466.7%6

Recent changes

Announcements that started or stopped since 23rd Sept 2026.

No announcement by AS4 started or stopped in this period.

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