Network Working Group                                            R. Bush
Internet-Draft                                                       IIJ
Updates: 2026 (if approved)                                    T. Narten
Expires: April 18, 2004                                  IBM Corporation
                                                        October 19, 2003

   Clarifying when Standards Track Documents may Refer Normatively to
                       Documents at a Lower Level

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.


   IETF procedures generally require that a standards track RFC may not
   have a normative reference to a document at a lower standards level.
   For example a standards track document may not have a normative
   reference to an informational RFC.  There are needs for exceptions to
   this rule, often caused by the IETF using informational RFCs to
   describe non-IETF standards, or IETF-specific modes of use of such
   standards. This document clarifies the procedure used in these

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1. Normative References Expected to be to Equal or Higher Level

   The Internet Standards Process [RFC2026] Section 4.2.4 specifies:

      Standards track specifications normally must not depend on other
      standards track specifications which are at a lower maturity level
      or on non standards track specifications other than referenced
      specifications from other standards bodies.

   One intent is to avoid creating a perception that a standard is more
   mature than it actually is.

2. The Need for Downward References

   There are a number of circumstances where a reference to a document
   at a lower maturity level may be needed.

   o  A standards track document may need to refer to a protocol
      developed by an external body but modified, adapted, or profiled
      by an IETF informational RFC, for example MD5 [RFC1321] and HMAC
      [RFC2104]. Note that this does not override the IETF's duty to see
      that the specification is indeed sufficiently clear to enable
      creation of interoperable implementations.

   o  A standards document may need to refer to a proprietary protocol,
      and the IETF normally documents proprietary protocols using
      informational RFCs.

   o  A migration or co-existence document may need to define a
      standards track mechanism for migration from, and/or co-existence
      with, an historic protocol, a proprietary protocol, or possibly a
      non-standards track protocol.

   o  There are exceptional procedural or legal reasons which force the
      target of the normative reference to be an informational or
      historical RFC, or for it to be at a lower standards level than
      the referring document.

3. The Procedure to be Used

   For Standards Track or BCP documents requiring normative reference to
   documents of lower maturity, the normal IETF Last Call procedure will
   be issued, with the need for the downward reference explicitly
   documented in the Last Call itself.  Any community comments on the
   appropriateness of downward references will be considered by the IESG
   as part of its deliberations.  Once a specific precedent has been set
   (i.e., the same exception has been made for a particular reference a

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   few times), the need for an explicit mention of the issue during Last
   Call may be waived.

   This procedure should not be used when the document to which the
   reference is being made could be advanced to the appropriate
   category. I.e., this is not intended as an easy way out of normal

4. Security Considerations

   This document is not known to create any new vulnerabilities for the
   internet.  On the other hand, inappropriate or excessive use of the
   process might be considered a down-grade attack on the quality of
   IETF standards, or worse, on the rigorous review of security aspects
   of standards.

5. Acknowlegnemts

   This document is the result of discussion within the IESG, with
   particular contribution by Harald Alvestrand, Steve Bellovin, Scott
   Bradner, Ned Freed, Jeff Schiller, and Bert Wijnen.

Normative References

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

Informative References

   [RFC1321]  Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
              April 1992.

   [RFC2104]  Krawczyk, H., Bellare, M. and R. Canetti, "HMAC:
              Keyed-Hashing for Message Authentication", RFC 2104,
              February 1997.

Authors' Addresses

   Randy Bush
   5147 Crystal Springs
   Bainbrisge Island, WA  98110

   Phone: +1 206 780 0431

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   Thomas Narten
   IBM Corporation
   P.O. Box 12195
   Research Triangle Park, NC  27709-2195

   Phone: +1 919 254 7798

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