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AS51809BRSK Limited

United KingdomRegistryRIPE NCCTypeEyeball

As of 11th November 2026, AS51809 (BRSK Limited), an access network registered in the United Kingdom with RIPE NCC, originates 39 IPv4 prefixes covering 31k addresses and 1 IPv6 prefix. By IPv4 address space that makes it the 5,689th-largest of the 80,747 networks we see originating IPv4, and the 157th-largest of 2,122 in the United Kingdom. It is seen behind 1 upstream network, most often AS212655 (YouFibre Limited), and in front of 1 downstream network. 83% 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.

At a glance

IPv4 prefixes

39

IPv6 prefixes

1

IPv4 addresses

31k

IPv6 /64s

34.4B

Upstream graph

The networks AS51809 is seen behind, one and two hops out, drawn from real AS paths.

AS51809Toward the internet core
Upstream graph for AS51809: 3 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS51809BRSK LimitedThis networkAS212655YouFibre LimitedAS2914NTT America, Inc.AS6461Zayo Bandwidth

Networks observed one and two hops upstream of AS51809 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

4

adjacent networks

Upstreams
125%
Peers
250%
Downstreams
125%

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

Upstreams of AS51809
NetworkCountryRelationshipPathsVantage pts
AS212655YouFibre LimitedGBPeer3,604138

Prefixes

All 40

The largest blocks AS51809 originates, widest first.

Largest prefixes originated by AS51809
PrefixAddressesVisibility
31.98.80.0/204.1k76/76
88.97.176.0/204.1k76/76
31.98.72.0/212k76/76
45.61.104.0/212k76/76
63.135.72.0/212k76/76
88.97.160.0/212k76/76
104.238.40.0/212k76/76
45.41.148.0/221k76/76
45.82.140.0/221k76/76
67.208.52.0/221k76/76

Routing health

How AS51809'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

  • Valid82.5%33
  • Invalid0.0%0
  • No ROA17.5%7

Propagation

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

Prefix sizes

IPv4 — 39 prefixes

IPv6 — 1 prefixes

  • /2934.4B × /64100.0%1

Recent changes

Announcements that started or stopped since 12th Oct 2026.

No announcement by AS51809 started or stopped in this period.

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