{"draft":"draft-ietf-lsr-igp-ureach-prefix-announce-11","doc_id":"RFC9929","title":"IGP Unreachable Prefix Announcement","authors":["P. Psenak, Ed.","C. Filsfils","D. Voyer","S. Hegde","G. Mishra"],"format":["HTML","TEXT","PDF","XML"],"page_count":"14","pub_status":"PROPOSED STANDARD","status":"PROPOSED STANDARD","source":"Link State Routing","abstract":"Summarization is often used in multi-area or multi-domain networks to\r\nimprove network efficiency and scalability. With summarization in\r\nplace, there is a need to signal loss of reachability to an\r\nindividual prefix covered by the summary. This enables fast\r\nconvergence by steering traffic, when applicable, away from the node\r\nwhich owns the prefix and is no longer reachable.\r\n\r\nThis document specifies protocol mechanisms in IS-IS and OSPF,\r\ntogether with two new flags, to advertise such prefix reachability\r\nloss.\r\n\r\nThe term \"OSPF\" in this document is used to refer to both OSPFv2 and\r\nOSPFv3.","pub_date":"February 2026","keywords":[],"obsoletes":[],"obsoleted_by":[],"updates":[],"updated_by":[],"see_also":[],"doi":"10.17487\/RFC9929","errata_url":null}