ASN & prefix explorer

What it shows

• For an AS number: who holds it, every IPv4 and IPv6 prefix it announces, its upstream and downstream neighbours ranked by how many collector peers see each link, and which of its routes have no IRR route object.
• For a prefix, or the route covering an IP address or domain: its origin AS, how many of RIPE's full-table peers see it, the upstreams and AS paths collectors around the world use to reach it, covering and more-specific routes, a week of BGP update activity and which networks have originated it over the years.
• Problems worth fixing: a single upstream, routes missing from the IRR (networks that build filters from it may drop them), more than one origin, more-specific routes from other networks inside your space, prefixes longer than /24 or /48, and routes that flap.

Data comes from RIPEstat: RIPE NCC's RIS route collectors, which peer with hundreds of networks worldwide, and the IRR databases. Nothing is sent to the network you look up.

Reading the results

Upstreams are the networks that appear just before an AS in collected paths. For an end network these are its transit providers; for a large network they include peers. Downstreams appear behind it: customers, or networks it peers with.

Visibility below 100% is common for a few peers, but a route most peers don't see is reachable from few places. The usual causes are filtering by networks that check RPKI or the IRR, or a prefix more specific than /24 (IPv4) or /48 (IPv6).

Questions

What is an AS number?

An autonomous system is a network with its own routing policy, such as an ISP, a cloud provider or a large company. Its AS number identifies it in BGP, the protocol networks use to tell each other which addresses they can reach.

Why does my prefix need an IRR route object?

Many transit providers and internet exchanges build their BGP filters from IRR databases such as RADB or your regional registry's. A route without a matching route object can be dropped, so parts of the internet can't reach you. RPKI ROAs are the newer, signed equivalent; publish both.

Is more than one origin AS a hijack?

Not necessarily. Anycast services and some multi-homed customers announce a prefix from several ASes on purpose. If you don't recognise an origin, check it in the origin history and with your providers, and make sure your RPKI ROAs only authorise the ASes you use.

How current is the data?

Routing status and paths are at most a few hours old; prefix lists cover the last two weeks. A change you made a few minutes ago may not show yet.