BGP Looking Glass

A read-only window into a network’s BGP table. It shows which routes the network has to a destination, the AS path each one takes, and attributes like next hop, communities, local preference and MED. It is the quickest way to answer “how does the internet reach this prefix from here?”

Live. Collectors stream every BGP update the moment they receive it, so the table here is normally only seconds behind the routers. The age on each path is how long since that peer last sent or changed it.

From collectors: small BGP speakers running in our network and in partners’ networks. Each one peers with nearby routers, receives their full IPv4 and IPv6 tables (it never announces anything back) and streams them here. Every peer is a separate vantage point, so the same prefix can take quite different paths from each.

With All peers, an address is matched to the single most specific prefix any peer has, and each peer’s path to that prefix is shown. A peer that only carries a less specific covering route shows none. Pick that peer on its own to see its most specific match, or query the covering prefix directly (with its /len).

Every path is checked against the RPKI and the routing registries using that path’s own origin AS, so a prefix two peers disagree about shows two different answers. RPKI Valid means a signed ROA authorises that AS to originate the prefix, Invalid means a ROA covers it but does not authorise this announcement, and NotFound means nobody has published one. The IRR badge names the registries holding a matching route object — or says the prefix is registered to a different AS, registered only as a less specific, or not registered at all. Hover any badge for the reasoning, or click it to open the full tool.

Not for the looking glass. It is a browser tool, so please don’t script against the page. For programmatic lookups, use the IP → ASN, ASN lookup, RPKI and IRR APIs.