BGP Route Policy Patterns

A predictable BGP policy separates route selection from route acceptance. The examples here use explicit prefix filters, named policy stages, and a default deny posture.^[1]

Policy boundaries

Start by defining which prefixes may cross the boundary. Apply attribute changes only after that set is known. Keep a final explicit deny statement so accidental additions fail closed.

Verification

• Inspect received and advertised routes before activation.
• Confirm the expected best path and attributes.
• Record a rollback command next to the change procedure.