SIPPING WG J. Elwell Internet-Draft Siemens Enterprise Communications Updates: RFC 3325 (if approved) Limited Intended status: Informational October 13, 2006 Expires: April 16, 2007 The use of Asserted Identity in the Session Initiation Protocol (SIP) UPDATE method draft-elwell-sipping-update-pai-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 16, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract SIP has a mechanism for conveying the asserted identity of the originator of a request by means of the P-Asserted-Identity header field. This header field is specified for use in requests using a number of SIP methods, in particular the INVITE method. However, it is not specified for use in requests using the SIP UPDATE method. This document extends RFC 3325 by allowing use of the P-Asserted- Elwell Expires April 16, 2007 [Page 1]
Internet-Draft Asserted Identity in SIP UPDATE October 2006 Identity header field in UPDATE requests. This work is being discussed on the sipping@ietf.org mailing list. Table of Contents 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. UAC Behaviour . . . . . . . . . . . . . . . . . . . . . . . 4 4.2. Proxy Behaviour . . . . . . . . . . . . . . . . . . . . . . 4 4.3. UAS Behaviour . . . . . . . . . . . . . . . . . . . . . . . 4 5. Security considerations . . . . . . . . . . . . . . . . . . . . 4 6. Normative References . . . . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 Intellectual Property and Copyright Statements . . . . . . . . . . 6 Elwell Expires April 16, 2007 [Page 2]
Internet-Draft Asserted Identity in SIP UPDATE October 2006 1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [2]. 2. Introduction SIP (RFC 3261 [1]) has a mechanism for conveying the asserted identity of the originator of a request by means of the P-Asserted- Identity header field (RFC 3325 [4]). This header field is specified for use in requests using a number of SIP methods, in particular the INVITE method. However, it is not specified for use in requests using the SIP UPDATE method (RFC 3311 [3]). This document extends RFC 3325 by allowing use of the P-Asserted-Identity header field in UPDATE requests. 3. Use cases There are several use cases that would benefit from the use of the P-Asserted-Identity header field in an UPDATE request. These use cases apply within a trusted environment where the use of asserted identity is appropriate (see RFC 3325). In one example an established call passes through a gateway to the PSTN. The gateway becomes aware that the remote party in the PSTN has changed, e.g., due to call transfer. By including the P-Asserted-Identity header field in an UPDATE request, the gateway can convey the identity of the new remote party to the peer SIP UA. Note that the (re-)INVITE method could be used in this situation. However, this forces an offer-answer exchange, which typically is not required in this situation. Also it involves 3 messages rather than 2. In another example, a B2BUA that provides third party call control (3PCC) wishes to join two calls together, one of which is still waiting to be answered and potentially is forked to different UAs. At this point in time it is not possible to trigger the normal offer- answer exchange between the two joined parties, because of the mismatch between a single dialog on the one side and potentially multiple early dialogs on the other side, so this action must wait until one of the called UAs answers. However, it would be useful to give an early indication to each user concerned of the identity of the user to which they will become connected when the call is answered. This can be achieved by the B2BUA sending an UPDATE Elwell Expires April 16, 2007 [Page 3]
Internet-Draft Asserted Identity in SIP UPDATE October 2006 request with a P-Asserted-Identity header field on the dialogs concerned. 4. Behaviour This updates RFC 3325 by allowing a P-Asserted-Identity header field to appear in an UPDATE request. 4.1. UAC Behaviour A UAC MAY include a P-Asserted-Identity header field in an UPDATE request to report the identity of the user on behalf of which the UAC is acting and whose identity the UAC is in a position to assert. This can be an UPDATE request sent specially for this purpose or an UPDATE request sent for some other purpose. 4.2. Proxy Behaviour If a UAC receives an UPDATE request containing a P-Asserted-Identity header field, it MUST behave as for any other request in accordance with the rules of RFC 3325 for a proxy. 4.3. UAS Behaviour If a UAC receives an UPDATE request containing a P-Asserted-Identity header field, it MUST behave as for any other request in accordance with the rules of RFC 3325 for a UAS. 5. Security considerations The use of asserted identity raises a number of security considerations, which are discussed fully in RFC 3325 [4]. This document does not introduce any additional security considerations. 6. Normative References [1] 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. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Rosenberg, J., "The Session Initiation Protocol (SIP) UPDATE Method", RFC 3311, September 2002. Elwell Expires April 16, 2007 [Page 4]
Internet-Draft Asserted Identity in SIP UPDATE October 2006 [4] Jennings, C., Peterson, J., and M. Watson, "Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks", RFC 3325, November 2002. Author's Address John Elwell Siemens Enterprise Communications Limited Technology Drive Beeston, Nottingham NG9 1LA UK Phone: +44 115 943 4989 Email: john.elwell@siemens.com Elwell Expires April 16, 2007 [Page 5]
Internet-Draft Asserted Identity in SIP UPDATE October 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). 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. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights 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 procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an 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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Elwell Expires April 16, 2007 [Page 6]