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AS5400British Telecommunications (International)

United KingdomRegistryRIPE NCCTypeCarrier

As of 26th September 2026, AS5400 (British Telecommunications…), a transit carrier registered in the United Kingdom with RIPE NCC, originates 86 IPv4 prefixes covering 735k addresses and 40 IPv6 prefixes. By IPv4 address space that makes it the 564th-largest of the 79,516 networks we see originating IPv4, and the 14th-largest of 2,074 in the United Kingdom. It is seen behind 37 upstream networks, most often AS3356 (Lumen (Level 3)) and AS1299 (Arelion (fka. Telia Carrier)), and in front of 60 downstream networks. 78% of its announcements have a valid RPKI ROA, and none are RPKI-invalid. 100% of its routes reach at least 90% of full-feed peers, and 1 prefix is also originated by another network.

At a glance

IPv4 prefixes

86

IPv6 prefixes

40

IPv4 addresses

735k

IPv6 /64s

4T

Upstream graph

The networks AS5400 is seen behind, one and two hops out, drawn from real AS paths.

AS5400Toward the internet core
Upstream graph for AS5400: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS5400British Telecommu…This networkAS1299Arelion (fka. Tel…AS3257GTT Communication…AS3356Lumen (Level 3)AS3491PCCW Global (HK) …AS6453TATA Communicatio…AS8888xTom Pty LtdAS13030Init7 (Switzerlan…AS2914NTT America, Inc.AS3549Lumen (fka. Globa…AS24516Virtutel Pty LtdAS8220COLTAS35280F5 Networks SARL

Networks observed one and two hops upstream of AS5400 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

280

adjacent networks

Upstreams
3713%
Peers
18365%
Downstreams
6021%

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

Upstreams of AS5400
NetworkCountryRelationshipPathsVantage pts
AS3356Lumen (Level 3)USPeer17,36949
AS1299Arelion (fka. Telia Carrier)SEPeer9,73643
AS6453TATA Communications (America) IncUSPeer6,27918
AS3491PCCW Global (HK) Ltd.HKPeer4,55410
AS3257GTT Communications Inc.USPeer4,33615
AS6939Hurricane Electric LLCUSPeer3,84415
AS2497Internet Initiative Japan Inc.JPPeer3,5365
AS174Cogent Communications, LLCUSPeer3,46019
AS7713PT Telkom Indonesia TbkIDPeer2,5782
AS6762Telecom Italia Sparkle (Seabone)ITPeer2,49411

Prefixes

All 126

The largest blocks AS5400 originates, widest first.

Largest prefixes originated by AS5400
PrefixAddressesVisibility
62.134.0.0/1665.5k81/81
62.180.0.0/1665.5k81/81
195.100.0.0/1665.5k81/81
195.163.0.0/1665.5k81/81
206.73.0.0/1665.5k81/81
213.15.0.0/1665.5k81/81
62.5.0.0/1732.8k81/81
62.102.0.0/1732.8k81/81
166.49.128.0/1732.8k81/81
62.173.192.0/1816.4k81/81

Routing health

How AS5400'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

  • Valid77.8%98
  • Invalid0.0%0
  • No ROA22.2%28

Propagation

  • Globally propagated90% of full-feed peers or more100.0%126
  • Partially propagated40% to 90%0.0%0
  • Seen by few peersUnder 40%0.0%0

Prefix sizes

IPv4 — 86 prefixes

IPv6 — 40 prefixes

  • /232.2T × /642.5%1
  • /25550B × /647.5%3
  • /2934.4B × /642.5%1
  • /324.3B × /6442.5%17
  • /3867.1M × /645.0%2
  • /3933.6M × /6420.0%8
  • /4016.8M × /6420.0%8

Recent changes

Announcements that started or stopped since 28th Aug 2026.

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