rfc9366.original   rfc9366.txt 
SIPCORE Working Group R. Sparks Internet Engineering Task Force (IETF) R. Sparks
Internet-Draft 23 August 2022 Request for Comments: 9366 March 2023
Updates: 3326 (if approved) Updates: 3326
Intended status: Standards Track Category: Standards Track
Expires: 24 February 2023 ISSN: 2070-1721
Multiple SIP Reason Header Field Values Multiple SIP Reason Header Field Values
draft-ietf-sipcore-multiple-reasons-01
Abstract Abstract
The SIP Reason Header Field as defined in RFC 3326 allows only one The SIP Reason header field as defined in RFC 3326 allows only one
Reason value per protocol value. Experience with more recently Reason value per protocol value. Experience with more recently
defined protocols shows it is useful to allow multiple values with defined protocols shows it is useful to allow multiple values with
the same protocol value. This update to RFC 3326 allows multiple the same protocol value. This document updates RFC 3326 to allow
values for an indicated registered protocol when that protocol multiple values for an indicated registered protocol when that
defines what the presence of multiple values means. protocol defines what the presence of multiple values means.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 24 February 2023. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9366.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 2 2. Conventions
3. Update to RFC3326 . . . . . . . . . . . . . . . . . . . . . . 3 3. Update to RFC 3326
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 3 6. References
6.1. Normative References . . . . . . . . . . . . . . . . . . 3 6.1. Normative References
6.2. Informative References . . . . . . . . . . . . . . . . . 4 6.2. Informative References
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 4 Acknowledgments
Appendix B. Changelog . . . . . . . . . . . . . . . . . . . . . 4 Author's Address
B.1. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
B.2. 01 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction 1. Introduction
The SIP Reason Header Field as defined in RFC 3326 allows only one The SIP Reason header field as defined in RFC 3326 allows only one
Reason value per protocol value. Experience with more recently Reason value per protocol value. Experience with more recently
defined protocols shows it is useful to allow multiple values with defined protocols shows it is useful to allow multiple values with
the same protocol value [STIRREASONS]. This update to RFC 3326 the same protocol value [STIRREASONS]. This document updates RFC
allows multiple values for an indicated registered protocol when that 3326 to allow multiple values for an indicated registered protocol
protocol defines what the presence of multiple values means. It does when that protocol defines what the presence of multiple values
not change the requirement in RFC 3326 restricting the header field means. It does not change the requirement in RFC 3326 restricting
contents to one value per protocol for those protocols that do not the header field contents to one value per protocol for those
define what multiple values mean. protocols that do not define what multiple values mean.
2. Conventions and Definitions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Update to RFC3326 3. Update to RFC 3326
The last paragraph of section 2 of [RFC3326] is replaced as follows: The last paragraph of Section 2 of [RFC3326] is replaced as follows:
OLD: OLD:
A SIP message MAY contain more than one Reason value (i.e., multiple | A SIP message MAY contain more than one Reason value (i.e.,
Reason lines), but all of them MUST have different protocol values | multiple Reason lines), but all of them MUST have different
(e.g., one SIP and another Q.850). An implementation is free to | protocol values (e.g., one SIP and another Q.850). An
ignore Reason values that it does not understand. | implementation is free to ignore Reason values that it does not
| understand.
NEW: NEW:
A SIP message MAY contain more than one Reason value (i.e., multiple | A SIP message MAY contain more than one Reason value (i.e.,
Reason lines). If the registered protocol for the Reason value | multiple Reason lines). If the registered protocol for the Reason
specifies what it means for multiple values to occur in one message, | value specifies what it means for multiple values to occur in one
more than one value for that protocol MAY be present. Otherwise, | message, more than one value for that protocol MAY be present.
there MUST be only one value per protocol provided (e.g., one SIP and | Otherwise, there MUST be only one value per protocol provided
another Q.850). An implementation is free to ignore Reason values | (e.g., one SIP and another Q.850). An implementation is free to
that it does not understand. | ignore Reason values that it does not understand.
4. Security Considerations 4. Security Considerations
This document adds no security considerations to the use of SIP. The This document adds no security considerations to the use of SIP. The
security considerations in [RFC3326] and those in any registered security considerations in [RFC3326] and those in any registered
protocols used in Reason header field values should be considered. protocols used in Reason header field values should be considered.
5. IANA Considerations 5. IANA Considerations
This document has no IANA actions. This document has no IANA actions.
6. References 6. References
6.1. Normative References 6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3326] Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason [RFC3326] Schulzrinne, H., Oran, D., and G. Camarillo, "The Reason
Header Field for the Session Initiation Protocol (SIP)", Header Field for the Session Initiation Protocol (SIP)",
RFC 3326, DOI 10.17487/RFC3326, December 2002, RFC 3326, DOI 10.17487/RFC3326, December 2002,
<https://www.rfc-editor.org/rfc/rfc3326>. <https://www.rfc-editor.org/info/rfc3326>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
6.2. Informative References 6.2. Informative References
[STIRREASONS] [STIRREASONS]
Wendt, C., "Identity Header Errors Handling", Work in Wendt, C., "Identity Header Errors Handling for STIR",
Progress, Internet-Draft, draft-ietf-stir-identity-header- Work in Progress, Internet-Draft, draft-ietf-stir-
errors-handling-03, 19 August 2022, identity-header-errors-handling-08, 25 February 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-stir- <https://datatracker.ietf.org/doc/html/draft-ietf-stir-
identity-header-errors-handling-03>. identity-header-errors-handling-08>.
Appendix A. Acknowledgments Acknowledgments
This text is based on discussions at a STIR working group interim This text is based on discussions at a STIR Working Group interim
meeting. Jean Mahoney and Russ Housley provided suggestions that meeting. Jean Mahoney and Russ Housley provided suggestions that
vastly improved the first attempts at assembling these words. vastly improved the first attempts at assembling these words.
Christer Holmberg, Dale Worley, Brian Rosen, Chris Wendt, and Paul Christer Holmberg, Dale Worley, Brian Rosen, Chris Wendt, and Paul
Kyzivat provided constructive discussion during SIPCORE working group Kyzivat provided constructive discussion during SIPCORE Working Group
adoption. adoption.
Appendix B. Changelog
(This section to be removed by the RFC editor.)
B.1. 00
* rename draft-sparks to draft-ietf. Add changelog.
B.2. 01
* expand a little on "Practice shows", referring to [STIRREASONS]
Author's Address Author's Address
Robert Sparks Robert Sparks
Email: rjsparks@nostrum.com Email: rjsparks@nostrum.com
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