{"draft":"draft-ietf-mpls-1stnibble-13","doc_id":"RFC9790","title":"IANA Registry and Processing Recommendations for the First Nibble Following a Label Stack","authors":["K. Kompella","S. Bryant","M. Bocci","G. Mirsky, Ed.","L. Andersson","J. Dong"],"format":["HTML","TEXT","PDF","XML"],"page_count":"15","pub_status":"PROPOSED STANDARD","status":"PROPOSED STANDARD","source":"Multiprotocol Label Switching","abstract":"This document creates a new IANA registry (called the \"Post-Stack\r\nFirst Nibble\" registry) for the first nibble (4-bit field)\r\nimmediately following an MPLS label stack. Furthermore, this document\r\npresents some requirements for registering new values and making the\r\nprocessing of MPLS packets easier and more robust. \r\n\r\nThe relationship between the IANA \"Post-Stack First Nibble\" registry\r\nand the \"IP Version Numbers\" registry (RFC 2780) is described in this\r\ndocument.\r\n\r\nThis document updates RFC 4928 by deprecating the heuristic method\r\nfor identifying the type of packet encapsulated in MPLS.","pub_date":"July 2025","keywords":["Post-stack header","Load-balancing"],"obsoletes":[],"obsoleted_by":[],"updates":["RFC4928"],"updated_by":[],"see_also":[],"doi":"10.17487\/RFC9790","errata_url":null}