# ASN Relationship Explorer

> An autonomous system at a glance: holder, country, BGP neighbours and announced prefixes. Explains an Autonomous System Number with RIPEstat data: registered holder and country, neighbours observed in RIPE RIS AS paths (left = towards the collectors, typically upstreams/peers; right = towards the origin, typically customers), announced IPv4/IPv6 prefixes with address-space totals, and a neighbour graph.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://asnrelationshipexplorer.usefulweb.site/ (interactive tool at https://asnrelationshipexplorer.usefulweb.site/tool)
- JSON API: POST https://asnrelationshipexplorer.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://asnrelationshipexplorer.usefulweb.site/api/v1/tool)
- OpenAPI: https://asnrelationshipexplorer.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://asnrelationshipexplorer.usefulweb.site/mcp - tool `asn_relationship_explorer`

## Inputs
- mode (select): Mode
- asn (text): AS number
- maxNeighbours (integer): Neighbours in the graph
- pasted (textarea): RIPEstat responses (JSON) - Pasted mode: {asn, asOverview, asnNeighbours?, announcedPrefixes?, rirStatsCountry?} — full RIPEstat responses or their "data" objects.

## Method
- as-overview: registered holder and whether the AS is announced; rir-stats-country: country of the registration (RIR statistics), not where the network operates.
- asn-neighbours: ASes adjacent to this AS in RIS AS paths. Per RIPEstat, "left" neighbours appear between this AS and the RIS collector (typically its upstream providers or peers) and "right" neighbours appear between it and the origin (typically customers). "Uncertain" = seen on the left only as direct peers of a RIS collector. "Power" = how often the adjacency was observed. Public BGP data cannot reliably separate peers from providers.
- announced-prefixes: prefixes originated by the AS over RIPEstat's default window (last 2 weeks); totals in /24 (IPv4) and /48 (IPv6) equivalents.
- Live mode also looks up holder names of the 10 strongest neighbours (as-overview).