Network & Infrastructure / BGP Policy & Internet Edge
Prefix-length filters and a missing emergency more-specific
An incident team advertises a more-specific prefix to steer around a failed edge, but a peer accepts only the aggregate. Existing filters may correctly reject the emergency announcement.
Environment and inputs: BGP speakers and route reflectors; policy syntax, RPKI integration and address-family behavior depend on the implementation. Diagnostic/design example; not tested on production equipment.
Collect the evidence
Compare the exact prefix length against local export filters, provider acceptance rules and applicable origin authorizations. Check actual receiver state instead of relying only on a successful local advertisement.
Explain the result
An aggregate's authorization and export permission do not automatically authorize every contained prefix length. Remote networks can enforce stricter acceptance than the originating router.
Plan the fix
Prepare emergency routing procedures with approved prefix ranges, lengths and provider policy before an incident. Update authorization and filters only within the address owner's explicit plan.
Check the result and rollback
Verify reception from independent networks and ensure the aggregate remains available as intended. Withdraw the temporary route after recovery and restore the reviewed steady-state export policy.