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AS1221Telstra Limited

AustraliaRegistryAPNICTypeEyeball

As of 26th September 2026, AS1221 (Telstra Limited), an access network registered in Australia with APNIC, originates 281 IPv4 prefixes covering 13.4M addresses and 2 IPv6 prefixes. By IPv4 address space that makes it the 55th-largest of the 79,480 networks we see originating IPv4, and the largest of 1,661 in Australia. It is seen behind 10 upstream networks, most often AS4637 (Telstra International Limited) and AS58511 (Swoop (Anycast Global Backbone)), and in front of 297 downstream networks. 45% of its announcements have a valid RPKI ROA, and none are RPKI-invalid. 99% of its routes reach at least 90% of full-feed peers, and 3 prefixes are also originated by another network.

At a glance

IPv4 prefixes

281

IPv6 prefixes

2

IPv4 addresses

13.4M

IPv6 /64s

17.6T

Upstream graph

The networks AS1221 is seen behind, one and two hops out, drawn from real AS paths.

AS1221Toward the internet core
Upstream graph for AS1221: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS1221Telstra LimitedThis networkAS4637Telstra Internati…AS7474SingTel Optus Pty…AS35280F5 Networks SARLAS38880Micron21 Datacent…AS58511Swoop (Anycast Gl…AS16552Tiggee LLCAS7473Singapore Telecom…AS32590Valve CorporationAS1299Arelion (fka. Tel…AS2914NTT America, Inc.AS9002RETN LimitedAS3491PCCW Global (HK) …

Networks observed one and two hops upstream of AS1221 in real AS paths. A thicker line means more vantage points saw that adjacency, so weight tracks how well attested it is — not how much traffic it carries. Adjacency is an observation; whether it is a transit purchase or a settlement-free peering is an inference, and is labelled as one wherever we show it.

Neighbouring networks

621

adjacent networks

Upstreams
102%
Peers
31451%
Downstreams
29748%

Networks carrying this one's traffic toward the rest of the internet.

Upstreams of AS1221
NetworkCountryRelationshipPathsVantage pts
AS4637Telstra International LimitedHKPeer187,003142
AS58511Swoop (Anycast Global Backbone)AUPeer21,8312
AS35280F5 Networks SARLFRPeer7,1456
AS38880Micron21 Datacentre Pty LtdAUPeer6,5803
AS7474SingTel Optus Pty LtdAUPeer1432
AS10026Telstra Global Internet Services Network BlocksJPPeer211
AS7545TPG Telecom LimitedAUPeer73
AS17559Spectrums Core NetworkAUPeer22
AS3356Lumen (Level 3)USPeer11
AS4826Vocus Connect International BackboneAUPeer11

Prefixes

All 283

The largest blocks AS1221 originates, widest first.

Largest prefixes originated by AS1221
PrefixAddressesVisibility
1.128.0.0/112.1M78/81
101.160.0.0/112.1M77/81
58.160.0.0/121M77/81
121.208.0.0/121M78/81
124.176.0.0/121M77/81
1.120.0.0/13524k77/81
60.224.0.0/13524k77/81
110.144.0.0/13524k77/81
120.144.0.0/13524k77/81
203.40.0.0/13524k78/81

Routing health

How AS1221's own announcements validate against RPKI and how far they propagate. The same measures for the whole routing table are on the routing table in numbers.

RPKI origin validation

  • Valid44.5%126
  • Invalid0.0%0
  • No ROA55.5%157

Propagation

  • Globally propagated90% of full-feed peers or more98.9%280
  • Partially propagated40% to 90%0.7%2
  • Seen by few peersUnder 40%0.4%1

Prefix sizes

IPv4 — 281 prefixes

IPv6 — 2 prefixes

  • /2017.6T × /6450.0%1
  • /4865.5k × /6450.0%1

Recent changes

Announcements that started or stopped since 27th Aug 2026.

  • Announced203.25.142.0/2422nd Sept 2026
  • Announced203.27.225.0/2422nd Sept 2026
  • Withdrawn129.41.78.0/2421st Sept 2026
  • Withdrawn203.6.170.0/2421st Sept 2026
  • Withdrawn203.8.107.0/2421st Sept 2026

Routing data derived from RouteViews MRT archives, BGPKIT relationship inference and public registry data.