Summary

  • BMP can export peer state, routing views, statistics and mirrored BGP messages, but each feed has a declared view and a collection boundary.
  • Seeing a route in Adj-RIB-In, Adj-RIB-Out or Loc-RIB does not independently prove next-hop resolution, FIB installation, hardware programming or packet delivery.
  • A credible forwarding claim needs an expiring receipt that joins BMP completeness with router readback, counters and active probes.

A complete-looking collector and a broken path

Imagine a monitoring station receiving updates without interruption. The route is present after inbound policy, selected in the local RIB and visible in the outbound view. Peer state is up and the collector dashboard is green. Traffic nevertheless fails because a next-hop adjacency did not resolve on one forwarding card after a programming fault.

Nothing in that sequence makes BMP misleading. The error is treating one observation plane as a verdict about another. A collector can faithfully report the routing state exposed by a router while the packet-processing state behind that route is incomplete, stale or unavailable.

Name the view before trusting the evidence

RFC 7854 gives operators a structured interface to received routing information, peer transitions, statistics and route mirroring. That richness is not the same as a universal snapshot. The receiver must know which router, BGP instance and peer it is observing, whether the view is pre- or post-policy, when the initial dump completed, and whether the transport or collector introduced a gap.

Route mirroring makes the boundary explicit: messages can be sampled, and the protocol includes an indication for lost messages. A live TCP session is therefore not proof of a lossless history. Collector restarts, buffering, backoff and configuration changes belong in the evidence chain.

RFC 8671 adds Adj-RIB-Out. Its post-policy view is designed to show what was transmitted to a peer after outbound policy, while the pre-policy view supports comparison and policy validation. That can answer an important question about advertisement. It still does not answer whether the advertising router installed a usable forwarding entry or whether the receiving network carried the traffic.

RFC 9069 adds Loc-RIB monitoring, exposing selected BGP routes that the base specification did not provide as a complete view. Selection is stronger evidence than receipt. It remains a control-plane decision, not a readback from the forwarding ASIC.

Control-plane telemetry needs a forwarding witness

RFC 9232 places BMP within control-plane telemetry. That classification is operationally useful. It tells an assurance designer where BMP is authoritative and where another witness is required.

For a forwarding claim, join the feed to next-hop resolution, RIB-to-FIB reconciliation, adjacency and label state, line-card programming, interface counters, drops and active probes. Align the timestamps closely enough to show that these observations describe the same route and failure window. Record absence as evidence too: if a platform cannot expose a FIB or hardware readback, the conclusion must remain narrower.

Sources