asn.dev

Observed topology

AS40123 R2G-2

Unclassified ARIN

Upstreams 5 carry this network
Downstreams 1 this network carries
Adjacent (IPv4) 6
Adjacent (IPv6) 0
Upstream graph Who carries AS40123, and who carries them, drawn as a map up to the transit-free core. 1 exchange Where AS40123 physically turns up to peer, and its address on each fabric.

Transit

Upstream networks

inferred

Networks observed carrying traffic for AS40123: the AS immediately before it in a routing path. Ranked by how many paths showed the relationship, which reflects how widely it is used, not how much traffic crosses it.

ASNetworkTypeFamiliesPaths seen
AS174Cogent Communications, LLCTransitIPv4133
AS13237euNetworks GmbHUnclassifiedIPv4124
AS8220COLT Technology Services Group LimitedHostingIPv479
AS3257GTT Communications Inc.TransitIPv441
AS3491PCCW Global (HK) Ltd.TransitIPv437

Transit

Downstream networks

inferred

Networks for which AS40123 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS22496Score Priority CorpUnclassifiedIPv42

Adjacency

Adjacent networks

observed

Every AS seen directly next to AS40123 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS174Cogent Communications, LLCTransitIPv4134
AS13237euNetworks GmbHUnclassifiedIPv4124
AS8220COLT Technology Services Group LimitedHostingIPv479
AS3257GTT Communications Inc.TransitIPv442
AS3491PCCW Global (HK) Ltd.TransitIPv437
AS22496Score Priority CorpUnclassifiedIPv42

Provenance

Where this comes from

Derived from routing tables collected at 2026-10-25 10:00 UTC by route-views2,rrc00, as seen from 75 BGP vantage points across 73.18M route entries. These are observations from those vantage points, not a complete or authoritative view of the internet.

Inferred from path position, not from any declaration by either party. A network appearing here is carrying these routes; whether that is a paid transit arrangement, a backup, or something else is not something routing data can tell you. Adjacency is not the same as peering. Being next to each other in a path covers paid transit, settlement-free peering and customer connections alike, and routing data cannot distinguish them. Treat this as "these networks exchange routes", nothing more specific.

Cross-check against RIPEstat or BGP.tools, which observe from a different and larger set of vantage points.