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AS59121Asahi Kasei Networks Corporation

JapanRegistryAPNIC

As of 10th November 2026, AS59121 (Asahi Kasei Networks Corporation), a network registered in Japan with APNIC, originates 3 IPv4 prefixes covering 33.3k addresses. By IPv4 address space that makes it the 5,445th-largest of the 80,733 networks we see originating IPv4, and the 214th-largest of 737 in Japan. It is seen behind 2 upstream networks, most often AS4725 (SoftBank Corp.) and AS4713 (NTT Communications Corporation (OCN)). None of its announcements have a valid RPKI ROA. 100% of its routes reach at least 90% of full-feed peers.

At a glance

IPv4 prefixes

3

IPv6 prefixes

0

IPv4 addresses

33.3k

IPv6 /64s

0

Upstream graph

The networks AS59121 is seen behind, one and two hops out, drawn from real AS paths.

AS59121Toward the internet core
Upstream graph for AS59121: 5 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS59121Asahi Kasei Netwo…This networkAS4713NTT Communication…AS4725SoftBank Corp.AS2497Internet Initiati…AS2914NTT America, Inc.AS17676SoftBank Corp.

Networks observed one and two hops upstream of AS59121 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

4

adjacent networks

Upstreams
250%
Peers
250%
Downstreams
00%

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

Upstreams of AS59121
NetworkCountryRelationshipPathsVantage pts
AS4725SoftBank Corp.JPPeer12376
AS4713NTT Communications Corporation (OCN)JPPeer10557

Prefixes

The largest blocks AS59121 originates, widest first.

Largest prefixes originated by AS59121
PrefixAddressesVisibility
138.212.0.0/1732.8k76/76
138.212.110.0/2425676/76
202.11.64.0/2425676/76

Routing health

How AS59121'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
  • Invalid0.0%0
  • No ROA100.0%3

Propagation

  • Globally propagated90% of full-feed peers or more100.0%3
  • Partially propagated40% to 90%0.0%0
  • Seen by few peersUnder 40%0.0%0

Prefix sizes

IPv4 — 3 prefixes

Recent changes

Announcements that started or stopped since 11th Oct 2026.

No announcement by AS59121 started or stopped in this period.

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