ASPA-based AS_PATH Verification for BGP Export

This document describes AS_PATH verification based on Autonomous System Provider Authorization (ASPA) for egress eBGP speakers. ASPA is a Resource Public Key Infrastructure (RPKI) object that allows an AS to register its transit provider ASes. Performing ASPA-based AS_PATH verification at egress can prevent the propagation of route leaks to external peers, check for local misconfigurations, and help detect potential ASPA registration errors. This approach complements ingress-side verification; it ensures coverage should ASPA deployment be absent at the ingress eBGP router of the AS.