Techniques for automatically identifying an edge-facing router in a network are provided. In one technique, data is obtained at a first router of a subscriber network. The data may be included in a DHCP message or a NDP RA message. The first router determines, based on the data, whether the first router is a service provider (SP)-facing router, which is a router that is coupled to a SP router and no other router in the subscriber network is logically between the SP-facing router and the SP router. If it is determined that the first router is an SP-facing router, then the first router stores identification data that identifies the first router as an SP-facing router. Otherwise, the first router stores identification data that identifies the first router as a non-SP-facing router.