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