asn.dev

Observed topology

AS2856 BT-UK-AS British Telecommunications Limited

Residential DROP-listed space RIPE

Upstreams 13 carry this network
Downstreams 151 this network carries
Adjacent (IPv4) 163
Adjacent (IPv6) 26
Upstream graph Who carries AS2856, and who carries them, drawn as a map up to the transit-free core. 1 exchange Where AS2856 physically turns up to peer, and its address on each fabric.

Transit

Upstream networks

All 13

Networks observed carrying traffic for AS2856: 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
AS5400British Telecommunications LimitedUnclassifiedIPv4 IPv623,332
AS9002RETN LimitedUnclassifiedIPv4 IPv63,278
AS6461Zayo BandwidthTransitIPv4 IPv61,106
AS50304Blix Solutions ASUnclassifiedIPv4 IPv61,090
AS3303Swisscom (Schweiz) AGResidentialIPv4 IPv61,088
AS17639Converge ICT Solutions Inc.UnclassifiedIPv4 IPv6550
AS48185team.blue NVUnclassifiedIPv4 IPv6550
AS50300CustodianDC LimitedUnclassifiedIPv4545
AS6206Netrouting B.V.HostingIPv4544
AS25180Exponential-E Ltd.UnclassifiedIPv442

All 13 upstreams →

Transit

Downstream networks

All 151

Networks for which AS2856 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS6871British Telecommunications LimitedResidentialIPv4 IPv63,663
AS2134Santander Global Technology and Operations, S.L.UnclassifiedIPv4986
AS49318Telefonica Tech UK LimitedUnclassifiedIPv4826
AS54113Fastly, Inc.HostingIPv4 IPv6720
AS201536SANDYX SYSTEMS LIMITEDUnclassifiedIPv4 IPv6635
AS25049Shell Information Technology International B.V.UnclassifiedIPv4471
AS21369Atos IT Services UK LtdUnclassifiedIPv4387
AS202206FAT MEDIA LTDUnclassifiedIPv4343
AS15248Metaswitch Networks Corp.UnclassifiedIPv4 IPv6340
AS28863Thales UK LimitedUnclassifiedIPv4293

All 151 downstreams →

Adjacency

Adjacent networks

All 166

Every AS seen directly next to AS2856 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS5400British Telecommunications LimitedUnclassifiedIPv4 IPv636,419
AS9002RETN LimitedUnclassifiedIPv4 IPv64,972
AS6871British Telecommunications LimitedResidentialIPv4 IPv63,663
AS50304Blix Solutions ASUnclassifiedIPv4 IPv61,810
AS3303Swisscom (Schweiz) AGResidentialIPv4 IPv61,707
AS6461Zayo BandwidthTransitIPv4 IPv61,659
AS2134Santander Global Technology and Operations, S.L.UnclassifiedIPv4986
AS48185team.blue NVUnclassifiedIPv4 IPv6968
AS17639Converge ICT Solutions Inc.UnclassifiedIPv4 IPv6908
AS50300CustodianDC LimitedUnclassifiedIPv4896

All 166 adjacent →

Provenance

Where this comes from

Derived from routing tables collected at 2026-11-09 10:00 UTC by route-views2,rrc00, as seen from 75 BGP vantage points across 73.03M 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.