asn.dev

Observed topology

AS51561 AS-ICUK

Unclassified RIPE NSP

Upstreams 24 carry this network
Downstreams 2 this network carries
Adjacent (IPv4) 23
Adjacent (IPv6) 12
Upstream graph Who carries AS51561, and who carries them, drawn as a map up to the transit-free core. 2 exchanges Where AS51561 physically turns up to peer, and its address on each fabric.

Transit

Upstream networks

All 24

Networks observed carrying traffic for AS51561: 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, LLCTransitIPv4 IPv6830
AS13335Cloudflare, Inc.HostingIPv4773
AS2914NTT America, Inc.TransitIPv4 IPv6764
AS3356Level 3 Parent, LLCTransitIPv4 IPv6764
AS6939Hurricane Electric LLCTransitIPv4 IPv6486
AS34549meerfarbig GmbH & Co. KGHostingIPv4 IPv6133
AS50304Blix Solutions ASUnclassifiedIPv487
AS24482SG.GSHostingIPv4 IPv658
AS48185team.blue NVUnclassifiedIPv4 IPv658
AS50300CustodianDC LimitedUnclassifiedIPv4 IPv658

All 24 upstreams →

Transit

Downstream networks

inferred

Networks for which AS51561 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS201060SNETTERTON TELECOM LIMITEDUnclassifiedIPv449
AS199204Webmate Internet Services Ltd.UnclassifiedIPv41

Adjacency

Adjacent networks

All 26

Every AS seen directly next to AS51561 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS174Cogent Communications, LLCTransitIPv4 IPv6830
AS2914NTT America, Inc.TransitIPv4 IPv6778
AS13335Cloudflare, Inc.HostingIPv4773
AS3356Level 3 Parent, LLCTransitIPv4 IPv6770
AS6939Hurricane Electric LLCTransitIPv4 IPv6498
AS34549meerfarbig GmbH & Co. KGHostingIPv4 IPv6136
AS50304Blix Solutions ASUnclassifiedIPv489
AS24482SG.GSHostingIPv4 IPv659
AS48185team.blue NVUnclassifiedIPv4 IPv659
AS50300CustodianDC LimitedUnclassifiedIPv4 IPv659

All 26 adjacent →

Provenance

Where this comes from

Derived from routing tables collected at 2026-10-28 10:00 UTC by route-views2,rrc00, as seen from 75 BGP vantage points across 73.21M 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.