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rfc:rfc3968

Network Working Group G. Camarillo Request for Comments: 3968 Ericsson Updates: 3427 December 2004 BCP: 98 Category: Best Current Practice

           The Internet Assigned Number Authority (IANA)
                Header Field Parameter Registry for
               the Session Initiation Protocol (SIP)

Status of This Memo

 This document specifies an Internet Best Current Practices for the
 Internet Community, and requests discussion and suggestions for
 improvements.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2004).

Abstract

 This document creates an Internet Assigned Number Authority (IANA)
 registry for the Session Initiation Protocol (SIP) header field
 parameters and parameter values.  It also lists the already existing
 parameters and parameter values to be used as the initial entries for
 this registry.

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
 2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  2
 3.  Use of the Registry  . . . . . . . . . . . . . . . . . . . . .  2
 4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  3
     4.1.  Header Field Parameters Sub-Registry . . . . . . . . . .  3
     4.2.  Registration Policy for SIP Header Field Parameters. . .  6
 5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
 6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  7
 7.  Normative References . . . . . . . . . . . . . . . . . . . . .  7
     Author's Address . . . . . . . . . . . . . . . . . . . . . . .  7
     Full Copyright Statement . . . . . . . . . . . . . . . . . . .  8

Camarillo Best Current Practice [Page 1] RFC 3968 SIP Parameter Registry December 2004

1. Introduction

 RFC 3261 [3] allows new header field parameters and new parameter
 values to be defined.  However, RFC 3261 omitted an IANA registry for
 them.  This document creates such a registry.
 RFC 3427 [4] documents the process to extend SIP.  This document
 updates RFC 3427 by specifying how to define and register new SIP
 header field parameters and parameter values.

2. Terminology

 In this document, the key words "MUST", "MUST NOT", "REQUIRED",
 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT
 RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as
 described in BCP 14, RFC 2119 [1] and indicate requirement levels for
 compliant implementations.

3. Use of the Registry

 SIP header field parameters and parameter values MUST be documented
 in an RFC in order to be registered by IANA.  This documentation MUST
 fully explain the syntax, intended usage, and semantics of the
 parameter or parameter value.  The intent of this requirement is to
 assure interoperability between independent implementations, and to
 prevent accidental namespace collisions between implementations of
 dissimilar features.
    Note that this registry, unlike other protocol registries, only
    deals with parameters and parameter values defined in RFCs (i.e.,
    it lacks a vendor-extension tree).  RFC 3427 [4] documents
    concerns with regards to new SIP extensions which may damage
    security, greatly increase the complexity of the protocol, or
    both.  New parameters and parameter values need to be documented
    in RFCs as a result of these concerns.
 RFCs defining SIP header field parameters or parameter values MUST
 register them with IANA as described below.
 Registered SIP header field parameters and parameter values are to be
 considered "reserved words".  In order to preserve interoperability,
 registered parameters and parameter values MUST be used in a manner
 consistent with that described in their defining RFC.
 Implementations MUST NOT utilize "private" or "locally defined" SIP
 header field parameters or parameter values that conflict with
 registered parameters.

Camarillo Best Current Practice [Page 2] RFC 3968 SIP Parameter Registry December 2004

    Note that although unregistered SIP header field parameters and
    parameter values may be used in implementations, developers are
    cautioned that usage of such parameters is risky.  New SIP header
    field parameters and parameter values may be registered at any
    time, and there is no assurance that these new registered
    parameters or parameter values will not conflict with unregistered
    parameters currently in use.
 Some SIP header field parameters only accept a set of predefined
 parameter values.  For example, a parameter indicating the transport
 protocol in use may only accept the predefined tokens TCP, UDP, and
 SCTP as valid values.  Registering all parameter values for all SIP
 header field parameters of this type would require a large number of
 subregistries.  Instead, we have chosen to register parameter values
 by reference.  That is, the entry in the parameter registry for a
 given header field parameter contains references to the RFCs defining
 new values of the parameter.  References to RFCs defining parameter
 values appear in double brackets in the registry.
 So, the header field parameter registry contains a column that
 indicates whether or not each parameter only accepts a set of
 predefined values.  Implementers of parameters with a "yes" in that
 column need to find all the valid parameter values in the RFCs
 provided as references.

4. IANA Considerations

 Section 27 of RFC 3261 [3] creates an IANA registry for method names,
 header field names, warning codes, status codes, and option tags.
 This specification creates a new sub-registry for header field
 parameters under the SIP Parameters registry.

4.1. Header Field Parameters Sub-Registry

 The majority of the SIP header fields can be extended by defining new
 parameters.  New SIP header field parameters are registered by the
 IANA.  When registering a new parameter for a header field or a new
 value for a parameter, the following information MUST be provided.
 o  Header field in which the parameter can appear.
 o  Name of the header field parameter being registered.
 o  Whether the parameter only accepts a set of predefined values.

Camarillo Best Current Practice [Page 3] RFC 3968 SIP Parameter Registry December 2004

 o  A reference to the RFC where the parameter is defined and to any
    RFC that defines new values for the parameter.  References to RFCs
    defining parameter values appear in double brackets in the
    registry.
 Parameters that can appear in different header fields MAY have the
 same name.  However, parameters that can appear in the same header
 field MUST have different names.
 The following are the initial values for this sub-registry.
 Header Field                  Parameter Name   Predefined  Reference
                                                  Values
 _____________________________________________________________________
 Accept                        q                    No     [RFC 3261]
 Accept-Encoding               q                    No     [RFC 3261]
 Accept-Language               q                    No     [RFC 3261]
 Authorization                 algorithm           Yes     [RFC 3261]
                                                          [[RFC 3310]]
 Authorization                 auts                 No     [RFC 3310]
 Authorization                 cnonce               No     [RFC 3261]
 Authorization                 nc                   No     [RFC 3261]
 Authorization                 nonce                No     [RFC 3261]
 Authorization                 opaque               No     [RFC 3261]
 Authorization                 qop                 Yes     [RFC 3261]
 Authorization                 realm                No     [RFC 3261]
 Authorization                 response             No     [RFC 3261]
 Authorization                 uri                  No     [RFC 3261]
 Authorization                 username             No     [RFC 3261]
 Authentication-Info           cnonce               No     [RFC 3261]
 Authentication-Info           nc                   No     [RFC 3261]
 Authentication-Info           nextnonce            No     [RFC 3261]
 Authentication-Info           qop                 Yes     [RFC 3261]
 Authentication-Info           rspauth              No     [RFC 3261]
 Call-Info                     purpose             Yes     [RFC 3261]
 Contact                       expires              No     [RFC 3261]
 Contact                       q                    No     [RFC 3261]
 Content-Disposition           handling            Yes     [RFC 3261]
 Event                         id                   No     [RFC 3265]
 From                          tag                  No     [RFC 3261]
 P-Access-Network-Info         cgi-3gpp             No     [RFC 3455]
 P-Access-Network-Info         utran-cell-id-3gpp   No     [RFC 3455]
 P-Charging-Function-Addresses ccf                  No     [RFC 3455]
 P-Charging-Function-Addresses ecf                  No     [RFC 3455]
 P-Charging-Vector             icid-value           No     [RFC 3455]
 P-Charging-Vector             icid-generated-at    No     [RFC 3455]
 P-Charging-Vector             orig-ioi             No     [RFC 3455]
 P-Charging-Vector             term-ioi             No     [RFC 3455]

Camarillo Best Current Practice [Page 4] RFC 3968 SIP Parameter Registry December 2004

 P-DCS-Billing-Info            called               No     [RFC 3603]
 P-DCS-Billing-Info            calling              No     [RFC 3603]
 P-DCS-Billing-Info            charge               No     [RFC 3603]
 P-DCS-Billing-Info            locroute             No     [RFC 3603]
 P-DCS-Billing-Info            rksgroup             No     [RFC 3603]
 P-DCS-Billing-Info            routing              No     [RFC 3603]
 P-DCS-LAES                    content              No     [RFC 3603]
 P-DCS-LAES                    key                  No     [RFC 3603]
 P-DCS-Redirect                count                No     [RFC 3603]
 P-DCS-Redirect                redirector-uri       No     [RFC 3603]
 Proxy-Authenticate            algorithm           Yes     [RFC 3261]
                                                          [[RFC 3310]]
 Proxy-Authenticate            domain               No     [RFC 3261]
 Proxy-Authenticate            nonce                No     [RFC 3261]
 Proxy-Authenticate            opaque               No     [RFC 3261]
 Proxy-Authenticate            qop                 Yes     [RFC 3261]
 Proxy-Authenticate            realm                No     [RFC 3261]
 Proxy-Authenticate            stale               Yes     [RFC 3261]
 Proxy-Authorization           algorithm           Yes     [RFC 3261]
                                                          [[RFC 3310]]
 Proxy-Authorization           auts                 No     [RFC 3310]
 Proxy-Authorization           cnonce               No     [RFC 3261]
 Proxy-Authorization           nc                   No     [RFC 3261]
 Proxy-Authorization           nonce                No     [RFC 3261]
 Proxy-Authorization           opaque               No     [RFC 3261]
 Proxy-Authorization           qop                 Yes     [RFC 3261]
 Proxy-Authorization           realm                No     [RFC 3261]
 Proxy-Authorization           response             No     [RFC 3261]
 Proxy-Authorization           uri                  No     [RFC 3261]
 Proxy-Authorization           username             No     [RFC 3261]
 Reason                        cause               Yes     [RFC 3326]
 Reason                        text                 No     [RFC 3326]
 Retry-After                   duration             No     [RFC 3261]
 Security-Client               alg                 Yes     [RFC 3329]
 Security-Client               ealg                Yes     [RFC 3329]
 Security-Client               d-alg               Yes     [RFC 3329]
 Security-Client               d-qop               Yes     [RFC 3329]
 Security-Client               d-ver                No     [RFC 3329]
 Security-Client               mod                 Yes     [RFC 3329]
 Security-Client               port1                No     [RFC 3329]
 Security-Client               port2                No     [RFC 3329]
 Security-Client               prot                Yes     [RFC 3329]
 Security-Client               q                    No     [RFC 3329]
 Security-Client               spi                  No     [RFC 3329]
 Security-Server               alg                 Yes     [RFC 3329]
 Security-Server               ealg                Yes     [RFC 3329]
 Security-Server               d-alg               Yes     [RFC 3329]
 Security-Server               d-qop               Yes     [RFC 3329]

Camarillo Best Current Practice [Page 5] RFC 3968 SIP Parameter Registry December 2004

 Security-Server               d-ver                No     [RFC 3329]
 Security-Server               mod                 Yes     [RFC 3329]
 Security-Server               port1                No     [RFC 3329]
 Security-Server               port2                No     [RFC 3329]
 Security-Server               prot                Yes     [RFC 3329]
 Security-Server               q                    No     [RFC 3329]
 Security-Server               spi                  No     [RFC 3329]
 Security-Verify               alg                 Yes     [RFC 3329]
 Security-Verify               ealg                Yes     [RFC 3329]
 Security-Verify               d-alg               Yes     [RFC 3329]
 Security-Verify               d-qop               Yes     [RFC 3329]
 Security-Verify               d-ver                No     [RFC 3329]
 Security-Verify               mod                 Yes     [RFC 3329]
 Security-Verify               port1                No     [RFC 3329]
 Security-Verify               port2                No     [RFC 3329]
 Security-Verify               prot                Yes     [RFC 3329]
 Security-Verify               q                    No     [RFC 3329]
 Security-Verify               spi                  No     [RFC 3329]
 Subscription-State            expires              No     [RFC 3265]
 Subscription-State            reason              Yes     [RFC 3265]
 Subscription-State            retry-after          No     [RFC 3265]
 To                            tag                  No     [RFC 3261]
 Via                           branch               No     [RFC 3261]
 Via                           comp                Yes     [RFC 3486]
 Via                           maddr                No     [RFC 3261]
 Via                           received             No     [RFC 3261]
 Via                           rport                No     [RFC 3581]
 Via                           ttl                  No     [RFC 3261]
 WWW-Authenticate              algorithm           Yes     [RFC 3261]
                                                          [[RFC 3310]]
 WWW-Authenticate              domain              Yes     [RFC 3261]
 WWW-Authenticate              nonce                No     [RFC 3261]
 WWW-Authenticate              opaque               No     [RFC 3261]
 WWW-Authenticate              qop                 Yes     [RFC 3261]
 WWW-Authenticate              realm                No     [RFC 3261]
 WWW-Authenticate              stale               Yes     [RFC 3261]

4.2. Registration Policy for SIP Header Field Parameters

 As per the terminology in RFC 2434 [2], the registration policy for
 SIP header field parameters and parameter values shall be "IETF
 Consensus."
 For the purposes of this registry, the parameter or the parameter
 value for which IANA registration is requested MUST be defined by an
 RFC.  There is no requirement that this RFC be standards-track.

Camarillo Best Current Practice [Page 6] RFC 3968 SIP Parameter Registry December 2004

5. Security Considerations

 The registry in this document does not in itself have security
 considerations.  However, as mentioned in RFC 3427, an important
 reason for the IETF to manage the extensions of SIP is to ensure that
 all extensions and parameters are able to provide secure usage.  The
 supporting RFC publications for parameter registrations described
 this specification MUST provide detailed security considerations for
 them.

6. Acknowledgements

 Jonathan Rosenberg, Henning Schulzrinne, Rohan Mahy, Dean Willis, Aki
 Niemi, Bill Marshall, Miguel A. Garcia-Martin, Jean Francois Mule,
 and Allison Mankin provided useful comments on this document.

7. Normative References

 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
     Levels", BCP 14, RFC 2119, March 1997.
 [2] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
     Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
 [3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
     Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
     Session Initiation Protocol", RFC 3261, June 2002.
 [4] Mankin, A., Bradner, S., Mahy, R., Willis, D., Ott, J., and B.
     Rosen, "Change Process for the Session Initiation Protocol
     (SIP)", BCP 67, RFC 3427, December 2002.

Author's Address

 Gonzalo Camarillo
 Ericsson
 Hirsalantie 11
 Jorvas  02420
 Finland
 EMail: Gonzalo.Camarillo@ericsson.com

Camarillo Best Current Practice [Page 7] RFC 3968 SIP Parameter Registry December 2004

Full Copyright Statement

 Copyright (C) The Internet Society (2004).
 This document is subject to the rights, licenses and restrictions
 contained in BCP 78, and except as set forth therein, the authors
 retain all their rights.
 This document and the information contained herein are provided on an
 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

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 Intellectual Property Rights or other rights that might be claimed to
 pertain to the implementation or use of the technology described in
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 might or might not be available; nor does it represent that it has
 made any independent effort to identify any such rights.  Information
 on the IETF's procedures with respect to rights in IETF Documents can
 be found in BCP 78 and BCP 79.
 Copies of IPR disclosures made to the IETF Secretariat and any
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 attempt made to obtain a general license or permission for the use of
 such proprietary rights by implementers or users of this
 specification can be obtained from the IETF on-line IPR repository at
 http://www.ietf.org/ipr.
 The IETF invites any interested party to bring to its attention any
 copyrights, patents or patent applications, or other proprietary
 rights that may cover technology that may be required to implement
 this standard.  Please address the information to the IETF at ietf-
 ipr@ietf.org.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Camarillo Best Current Practice [Page 8]

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