Subject: [Technical Errata Reported] RFC6564 (4423)

From: RFC Errata System <[email-masked]>
Date: Mon, 20 Jul 2015 05:44:33 -0700 (PDT)

The following errata report has been submitted for RFC6564,
"A Uniform Format for IPv6 Extension Headers".

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=6564&eid=4423

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Type: Technical
Reported by: Fernando Gont <[email-masked]>

Section: 5

Original Text
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   Any IPv6 extension headers defined in the future, keeping in mind the
   restrictions specified in Section 3 and also the restrictions
   specified in [RFC2460], MUST use the consistent format defined in
   Figure 1.  This minimizes breakage in intermediate nodes that examine
   these extension headers.

Corrected Text
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There's a bug in the logic of this document. Essentially:

   A key problem with the Uniform Format for IPv6 Extension Headers
   [RFC6564] lies in that both IPv6 Extension Headers and Transport
   Protocols share the same namespace ("Next Header" registry/
   namespace).  Thus, given an "unknown Next Header value", it is
   impossible to tell whether the aforementioned value refers to an IPv6
   Extension Header that employs the aforementioned uniform format, or
   an "unknown" upper-layer protocol (e.g. an "unknown" transport
   protocol).  That is, while [RFC6564] specifies the syntax for the
   Uniform Format for IPv6 Extension Headers, but it does not provide a
   mechanism for a node to identify whether the aforementioned format is
   being employed in the first place.

This problem is discussed in: draft-gont-6man-rfc6564bis.

Notes
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The problem is not specifically with Section 5, but rather with the logic in the document.

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RFC6564 (draft-ietf-6man-exthdr-06)
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Title               : A Uniform Format for IPv6 Extension Headers
Publication Date    : April 2012
Author(s)           : S. Krishnan, J. Woodyatt, E. Kline, J. Hoagland, M. Bhatia
Category            : PROPOSED STANDARD
Source              : IPv6 Maintenance
Area                : Internet
Stream              : IETF
Verifying Party     : IESG