    Internet Engineering Task Force (IETF)                       C. Holmberg
    Request for Comments: 7913                                      Ericsson
    Updates: 7315                                                  June 2016
    Category: Informational
    ISSN: 2070-1721

                       P-Access-Network-Info ABNF Update

    Abstract

       This document updates RFC 7315, by modifying the extension-access-
       info part of the P-Access-Network-Info header field Augmented Backus-
       Naur Form (ABNF), and by adding the following 'access-info' header
       field parameter values to the list of 'access-info' header field
       parameter values in the ABNF: 'operator-specific-GI' and
       'utran-sai-3gpp'.  The values are defined in the ABNF but are not
       included in the list.

    Status of This Memo

       This document is not an Internet Standards Track specification; it is
       published for informational purposes.

       This document is a product of the Internet Engineering Task Force
       (IETF).  It represents the consensus of the IETF community.  It has
       received public review and has been approved for publication by the
       Internet Engineering Steering Group (IESG).  Not all documents
       approved by the IESG are a candidate for any level of Internet
       Standard; see Section 2 of RFC 7841.

       Information about the current status of this document, any errata,
       and how to provide feedback on it may be obtained at
       http://www.rfc-editor.org/info/rfc7913.

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    Copyright Notice

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       document authors.  All rights reserved.

       This document is subject to BCP 78 and the IETF Trust's Legal
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       described in the Simplified BSD License.

    Table of Contents

       1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
       2.  Update to RFC 7315  . . . . . . . . . . . . . . . . . . . . .   3
       3.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
       4.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
       Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   4
       Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

    1.  Introduction

       [RFC7315] defines the Session Initiation Protocol (SIP) [RFC3261]
       P-Access-Network-Info header field.

       The header field syntax contains an 'access-info' header field
       parameter, with a set of pre-defined values.  Most pre-defined values
       follow the 'generic-param' rule [RFC3261].  However, currently the
       Augmented Backus-Naur Form (ABNF) [RFC5234] in [RFC7315] requires new
       values to follow the 'gen-value' rule [RFC3261], which is more
       restrictive than 'generic-param'.  There is no justification for the
       restriction, and new values have already been defined following the
       'generic-param' rule.

       The ABNF also defines the following 'access-info' header field
       parameter values: 'operator-specific-GI' and 'utran-sai-3gpp'.
       However, the values are not included in the list of 'access-info'
       values.

       This document updates Section 5.4 of [RFC7315], by modifying the
       extension-access-info part of the P-Access-Network-Info header field
       ABNF.

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    RFC 7913                        PANI ABNF                      June 2016

       As the P-Access-Network-Info header field is mainly used in networks
       defined by the 3rd-Generation Partnership Project (3GPP), where new
       values following the 'generic-param' rule have been defined
       [TS.3GPP.24.229], the update is not considered to cause issues with
       backward compatibility.

    2.  Update to RFC 7315

       This section updates the ABNF defined in Section 5.4 of RFC 7315, as
       described below:

      Old syntax:

          access-info            = cgi-3gpp / utran-cell-id-3gpp /
                                   dsl-location / i-wlan-node-id /
                                   ci-3gpp2 / eth-location /
                                   ci-3gpp2-femto / fiber-location /
                                   np / gstn-location /local-time-zone /
                                   dvb-rcs2-node-id / extension-access-info
          np                     = "network-provided"
          extension-access-info  = gen-value

      New syntax:

          access-info            = cgi-3gpp / utran-cell-id-3gpp /
                                   dsl-location / i-wlan-node-id /
                                   ci-3gpp2 / eth-location /
                                   ci-3gpp2-femto / fiber-location /
                                   np / gstn-location /local-time-zone /
                                   dvb-rcs2-node-id / operator-specific-GI /
                                   utran-sai-3gpp / extension-access-info
          np                     = "network-provided"
          extension-access-info  = generic-param

    3.  Security Considerations

       The security considerations for the P-Access-Network-Info header
       field are defined in [RFC7315].  The ABNF update defined in this
       document does not impact the security considerations.

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    4.  Normative References

       [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
                  A., Peterson, J., Sparks, R., Handley, M., and E.
                  Schooler, "SIP: Session Initiation Protocol", RFC 3261,
                  DOI 10.17487/RFC3261, June 2002,
                  <http://www.rfc-editor.org/info/rfc3261>.

       [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
                  Specifications: ABNF", STD 68, RFC 5234,
                  DOI 10.17487/RFC5234, January 2008,
                  <http://www.rfc-editor.org/info/rfc5234>.

       [RFC7315]  Jesske, R., Drage, K., and C. Holmberg, "Private Header
                  (P-Header) Extensions to the Session Initiation Protocol
                  (SIP) for the 3GPP", RFC 7315, DOI 10.17487/RFC7315, July
                  2014, <http://www.rfc-editor.org/info/rfc7315>.

       [TS.3GPP.24.229]
                  3GPP, "IP multimedia call control protocol based on
                  Session Initiation Protocol (SIP) and Session Description
                  Protocol (SDP); Stage 3", 3GPP TS 24.229 13.5.1, March
                  2016, <http://www.3gpp.org/ftp/Specs/html-info/24229.htm>.

    Acknowledgments

       Thanks to Ben Campbell, Cullen Jennings, Gonzalo Salgueiro, Jean
       Mahoney, Menachem Dodge, Olafur Gudmundsson, Paul Kyzivat, and the
       3GPP community for providing guidance, input, and comments on the
       document.

    Author's Address

       Christer Holmberg
       Ericsson
       Hirsalantie 11
       Jorvas  02420
       Finland

       Email: christer.holmberg@ericsson.com

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