New H3C Technologies China Mobile In link-state Interior Gateway Protocols (IGPs) such as OSPF and IS- IS, the router ID (or system ID) serves as a unique identifier for routers within a routing domain. Duplicate router IDs can lead to severe network instability, including persistent Link State Advertisement (LSA/LSP) flooding, inconsistent Link State Databases (LSDBs), and permanent forwarding loops. This document defines mechanisms for detecting such conflicts between non-adjacent routers and proposes procedures to alert network operators, along with defining the corresponding YANG interface and event YANG notifications for OAM operations.