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dispatch                                                       R. Jesske
Internet-Draft                                          Deutsche Telekom
Updates: RFC7976 (if approved)                         November 24, 2020
Intended status: Informational
Expires: May 28, 2021

     Update to Private Header Field P-Visited-Network-ID in Session
            Initiation Protocol (SIP) Requests and Responses


   The Third Generation Partnership Project (3GPP) has identified cases
   where the private header field P-Visited-Network-ID SIP private
   header extensions, which is defined in RFC 7315 and updated by RFC
   7976, needs to be included in SIP requests and responses.  This
   document updates RFC 7976, in order to allow inclusion of the P-
   Visited-Network-ID header field in responses.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 28, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must

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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Applicability of P-Visited-Network-ID in responses  . . . . .   2
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   3
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   The Third Generation Partnership Project (3GPP) has identified cases
   where different Session Initiation Protocol (SIP) [RFC3261] private
   header extensions referred to as "P-" header fields, and defined in
   [RFC7315], need to be included in SIP requests and responses which is
   currently not allowed according to [RFC7315].  This document updates
   [RFC7315], to allow the inclusion of the affected "P-" header fields
   in such requests and responses.  This document also makes updates for
   [RFC7976] to fix misalignments that occurred when [RFC7315] was
   updated for specific "P-" header fields which are mainly used in (and
   in most cases, only defined for) networks defined by the 3GPP.  The
   updates defined in this document will not cause backward-
   compatibility problems in 3GPP networks which are using

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "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.

3.  Applicability of P-Visited-Network-ID in responses

   In [RFC7976] section 3.  "Updates to RFC 7315" the P-Visited-Network-
   ID header field was restricted to the following: The P-Visited-
   Network-ID header field can appear in all SIP methods except ACK,
   BYE, CANCEL, NOTIFY, PRACK, INFO, and UPDATE.  This document allows
   the use of the P-Visited-Network-ID header field additionally within
   Responses as follows: Any SIP Response message, except for a 100
   (Trying), MAY contain a P-Visited-Network-ID header field.  The P-

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   Visited-Network-ID header field is not needed in the 100 (Trying)
   responses, since they are transmitted hop by hop, not end to end.

4.  Security Considerations

   The security considerations for these "P-" header fields are defined
   in [RFC7315].  This specification allows some header fields to be
   present in messages where they were previously not allowed, and the
   security considerations and assumptions described in [RFC7315] (e.g.,
   regarding only sending information to trusted entities) also apply to
   those messages.  That does not cause any security issues, but
   implementors need to be aware that implementations may not have been
   updated according to this document, and take proper actions if a
   header field does not occur, in a message where it should occur or
   occurs in a message where it should not occur.  The security and
   privacy considerations for the P-Visited-Network-ID header field are
   similar to those for the other SIP responses discussed in [RFC7315].

5.  Acknowledgments

   The author would like to acknowledge the constructive feedback
   provided by Michael Kreipl

6.  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,

   [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,

   [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, <https://www.rfc-editor.org/info/rfc7315>.

   [RFC7976]  Holmberg, C., Biondic, N., and G. Salgueiro, "Updates to
              Private Header (P-Header) Extension Usage in Session
              Initiation Protocol (SIP) Requests and Responses",
              RFC 7976, DOI 10.17487/RFC7976, September 2016,

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              3rd Generation Partnership Project, "3rd Generation
              Partnership Project; Technical Specification Group Core
              Network and Terminals; IP multimedia call control protocol
              based on Session Initiation Protocol (SIP) and Session
              Description Protocol (SDP); Stage 3", TS 24.229, V 14.4.0,
              March 2017.

Author's Address

   Roland Jesske
   Deutsche Telekom
   Heinrich-Hertz Str. 3-7
   Darmstadt  64295

   Email: r.jesske@telekom.de
   URI:   www.telekom.de

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