asn.dev

Observed topology

AS1221 ASN-TELSTRA - Telstra Limited

Mobile APNIC

Upstreams 3 carry this network
Downstreams 298 this network carries
Adjacent (IPv4) 303
Adjacent (IPv6) 67
Upstream graph Who carries AS1221, and who carries them, drawn as a map up to the transit-free core. 0 exchanges Where AS1221 physically turns up to peer, and its address on each fabric.

Transit

Upstream networks

inferred

Networks observed carrying traffic for AS1221: 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
AS4637Telstra GlobalUnclassifiedIPv4 IPv615,547
AS4608Asia Pacific Network Information CentreUnclassifiedIPv4276
AS35280F5 Networks SARLHostingIPv4276

Transit

Downstream networks

All 298

Networks for which AS1221 was observed as the last hop before the origin, meaning it appears to provide them transit.

ASNetworkTypeFamiliesPaths seen
AS135887Belong (Telstra Limited)UnclassifiedIPv4 IPv627,421
AS20940Akamai International B.V.HostingIPv4 IPv65,411
AS7545TPG Telecom LimitedResidentialIPv44,631
AS16509Amazon.com, Inc.HostingIPv4 IPv64,108
AS45763Opticomm Co Pty LtdResidentialIPv4 IPv62,969
AS4764Aussie BroadbandResidentialIPv4 IPv61,949
AS10235National Australia Bank LimitedUnclassifiedIPv41,706
AS9893CenitexUnclassifiedIPv41,392
AS18055Department of Human ServicesUnclassifiedIPv4 IPv6897
AS37978Networking TasmaniaUnclassifiedIPv4823

All 298 downstreams →

Adjacency

Adjacent networks

All 305

Every AS seen directly next to AS1221 in a routing path, in either direction.

ASNetworkTypeFamiliesPaths seen
AS4637Telstra GlobalUnclassifiedIPv4 IPv6573,259
AS4608Asia Pacific Network Information CentreUnclassifiedIPv4 IPv6470,199
AS135887Belong (Telstra Limited)UnclassifiedIPv4 IPv627,421
AS20940Akamai International B.V.HostingIPv4 IPv69,773
AS7545TPG Telecom LimitedResidentialIPv45,209
AS4764Aussie BroadbandResidentialIPv4 IPv64,393
AS16509Amazon.com, Inc.HostingIPv4 IPv64,147
AS9507NextHop Pty LtdUnclassifiedIPv4 IPv63,204
AS45763Opticomm Co Pty LtdResidentialIPv4 IPv63,174
AS49915Megaport (UK) LimitedUnclassifiedIPv4 IPv63,155

All 305 adjacent →

Provenance

Where this comes from

Derived from routing tables collected at 2026-11-07 10:00 UTC by route-views2,rrc00, as seen from 75 BGP vantage points across 72.97M 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.