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RFC 9790: IANA Registry and Processing Recommendations for the First Nibble Following a Label Stack

In plain English — editorial summary, not part of the RFC

This document creates a new IANA registry (called the "Post-Stack First Nibble" registry) for the first nibble (4-bit field) immediately following an MPLS label stack. Furthermore, this document presents some requirements for registering new values and making the processing of MPLS packets easier and more robust. The relationship between the IANA "Post-Stack First Nibble" registry and the "IP Version Numbers" registry (RFC 2780) is described in this document. This document updates RFC 4928 by deprecating the heuristic method for identifying the type of packet encapsulated in MPLS.

Document record

Document ID
RFC9790
Published
July 2025
Authors
K. Kompella; S. Bryant; M. Bocci; G. Mirsky; L. Andersson; J. Dong
Status
PROPOSED STANDARD
Stream
IETF
Area
rtg
Pages
15
Also known as
—
Updates:
RFC 4928

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The document record above — title, authors, date, status, stream, area, relationships, DOI and errata — is imported verbatim from the public RFC Editor index. The “in plain English” section is editorial: written by The metasystema editorial team, not part of the RFC. Where the two differ, the RFC text governs.

Last checked against the RFC Editor index on . RFCs are never revised after publication; changes are issued as new documents.

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canonical URL: /rfc/9790-iana-registry-and-processing-recommendations-for-the-first-nibble-following-a-la