Summary

  • Thomas Holterbach told RIPE 93 that ordinary BGP collection sessions at Internet exchanges miss filtered routes and peer-state events. BMP can expose routes before and after policy, alternate paths and session changes when the route-server implementation exports those stages.
  • His October 2026 proof of concept covered route-server BMP feeds from three smaller IXPs and roughly 60 participant BMP sessions. The added visibility makes storage, fast queries and decisions about data sharing part of the monitoring design.

The missing route has several suspects

An operator expects a prefix through an exchange and sees it vanish. The participant might have changed an export policy. The route server might have filtered the announcement. A peering session might have fallen. Or a better path might have displaced it. In his RIPE 93 presentation, Holterbach argued that a collector fed by an ordinary BGP session cannot see enough of the route server's decision path to sort those explanations. Some looking glasses query route-server software directly; his target was the limited view of a collection session that receives only what is sent to it.

BMP offers a more revealing diary. It can carry pre-policy and post-policy route streams, peer-up and peer-down events, and, with the relevant extensions and deployment support, views of outbound routes. RFC 7854 defines the inbound monitoring and peer-state messages; RFC 8671 adds outbound support. In the official session abstract, Holterbach points to filtered and non-best routes as evidence an operator cannot assume will appear in a normal collector feed. The useful question becomes which stage was actually exported, not whether a dashboard has a green light.

More eyes mean more bytes

Holterbach reported three smaller IXPs exporting from their route servers at the time of the talk: one using FRRouting, two BIRD. About 60 participant BMP sessions added views into roughly 200 participant-to-route-server sessions and more than 1,000 bilateral sessions. Those were his reported deployment counts in October 2026, a working sample rather than a global IXP census. He described scalable storage and query speed as the central engineering tension. In the Q&A, another operator warned that monitoring outbound routes across 1,500 peer connections could multiply updates sharply when one peer flaps.

There is also a publication decision. Holterbach said a richer public feed could reveal route policy to attackers as well as help defenders diagnose incidents. Operators can choose which sessions to export and which data a platform retains. The discussion did not settle a universal sharing rule; it named the people who have to make the choice. A collector cannot repair a route. It can leave a trace precise enough to show whether the loss began at the participant, the filter, the session or the path-selection step.

Sources: RIPE 93 talk; plenary transcript; RFC 7854; RFC 8671.