China Mobile China Mobile New H3C Technologies Arrcus, Inc. ZTE Corporation In certain scenarios, it is necessary to advertise unreachable links in OSPF, which should be explicitly excluded from the related SPF calculation. This document specifies using LSLinkInfinity(0xffff) to advertise an OSPF link as unreachable. Stub Router Advertisement (RFC 6987) defines MaxLinkMetric (0xffff) to indicate a router-LSA link should not be used for transit traffic. This document updates RFC 6987 and RFC 8770. When an OSPFv2 router supports the Unreachable Link support capability defined in this document, the OSPFv2 stub router MaxLinkMetric(0xffff) MUST be updated to MaxReachableLinkMetric(0xfffe).