Zhongguancun Laboratory Tsinghua University China Mobile China Telecom Huawei Technologies The Resource Public Key Infrastructure (RPKI) and Route Origin Validation (ROV) have significantly improved inter-domain routing security. However, thousands of RPKI-invalid routes - the vast majority caused by misconfiguration or synchronization delays - persistently appear in the global routing table. Many of these self- inflicted invalid routes originate from autonomous systems (ASes) that could have easily blocked them before advertisement. This document defines a *Best Current Practice (BCP)* for *source pre-validation*: the practice by which an originating AS checks its intended BGP announcement against its local RPKI cache *before* sending it to eBGP neighbors. Routes that would be evaluated as Invalid (or NotFound for strict mode) are blocked, logged, and *MUST be cached* for later re-evaluation, enabling automatic recovery when RPKI data changes. Routes evaluated as Valid or NotFound(for default mode) may be advertised normally. This BCP complements existing standards RFC8893 & RFC9324 by focusing on *mandatory deployment at the origin* and on *outbound caching* of suppressed routes. It provides operational guidance for deployment, cache management, and handling of RPKI data updates. Implementation of this BCP reduces self-inflicted invalid routes, improves global routing stability, and encourages wider ROV adoption.