asn.dev

Observed topology

AS2856 BT-UK-AS BTnet UK Regional network

Residential DROP-listed space RIPE

Upstreams 12 carry this network
Downstreams 149 this network carries
Adjacent (IPv4) 160
Adjacent (IPv6) 27
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 12

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 IPv622,672
AS9002RETN LimitedUnclassifiedIPv4 IPv63,823
AS6461Zayo BandwidthTransitIPv4 IPv61,101
AS50304Blix Solutions ASUnclassifiedIPv4 IPv61,088
AS3303Swisscom (Schweiz) AGResidentialIPv4 IPv61,080
AS48185team.blue NVUnclassifiedIPv4 IPv6549
AS17639Converge ICT Solutions Inc.UnclassifiedIPv4 IPv6547
AS50300CustodianDC LimitedUnclassifiedIPv4544
AS6206Netrouting B.V.HostingIPv4541
AS25180Exponential-E Ltd.UnclassifiedIPv432

All 12 upstreams →

Transit

Downstream networks

All 149

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.UnclassifiedIPv41,003
AS49318TELEFONICA TECH UK MANAGED SERVICES LTDUnclassifiedIPv4826
AS54113Fastly, Inc.HostingIPv4 IPv6728
AS201536SANDYX SYSTEMS LIMITEDUnclassifiedIPv4 IPv6626
AS25049Shell Information Technology International B.V.UnclassifiedIPv4472
AS21369Atos IT Services UK LtdUnclassifiedIPv4387
AS202206FAT MEDIA LTDUnclassifiedIPv4343
AS15248Metaswitch Networks Corp.UnclassifiedIPv4 IPv6339
AS28863Thales UK LimitedUnclassifiedIPv4295

All 149 downstreams →

Adjacency

Adjacent networks

All 163

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

ASNetworkTypeFamiliesPaths seen
AS5400British Telecommunications LimitedUnclassifiedIPv4 IPv635,620
AS9002RETN LimitedUnclassifiedIPv4 IPv66,058
AS6871British Telecommunications LimitedResidentialIPv4 IPv63,663
AS50304Blix Solutions ASUnclassifiedIPv4 IPv61,818
AS3303Swisscom (Schweiz) AGResidentialIPv4 IPv61,707
AS6461Zayo BandwidthTransitIPv4 IPv61,654
AS2134Santander Global Technology and Operations, S.L.UnclassifiedIPv41,003
AS48185team.blue NVUnclassifiedIPv4 IPv6970
AS50300CustodianDC LimitedUnclassifiedIPv4920
AS17639Converge ICT Solutions Inc.UnclassifiedIPv4 IPv6910

All 163 adjacent →

Provenance

Where this comes from

Derived from routing tables collected at 2026-10-23 10:00 UTC by route-views2,rrc00, as seen from 75 BGP vantage points across 73.15M 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.