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. A collector sits in one location and can peer with several different networks there. Each of those is a session, sending its own full IPv4 and IPv6 table (nothing is ever announced back). So one collector in Tampa might carry a session with one transit provider and another with a local network, and the same prefix can look quite different down each. Every session is its own vantage point and can be queried on its own.

That’s great, thank you! Every session adds another vantage point for everyone who uses the looking glass. Please email info at notoolkit dot com and we’ll take it from there.

With Everywhere, an address is matched to the single most specific prefix any session has, and then each session’s path to that prefix is shown. A session that only carries a less specific covering route shows none. Query that session on its own to see its most specific match, or ask for 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 authorizes that AS to originate the prefix, Invalid means a ROA covers it but does not authorize this announcement, and NotFound means nobody has published one. The ASPA badge checks the whole AS path against the providers each AS has published: Valid means it is provably valley-free, Invalid means it went down and then up again somewhere (a route leak, or an ASPA missing a provider), and Unknown means some AS on it has not published an ASPA yet. It is read as a route from a provider, since that is what a full-table session is. 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.