SIP Gerhard Ott Internet Draft Martin Huelsemann Expires: January 2008 Deutsche Telekom Intended Status: private Document: draft-ott-sip-serv-indication-notification-00 Expires: December 2007 June 2007 Private Header (P-Header) Extensions to the Session Initiation Protocol (SIP) for the support of the Services for the European Telecommunications Standards Institute, draft-ott-sip-serv-indication-notification-00 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 December 6, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document describes a set of private Session Initiation Protocol (SIP) headers (P-headers) used in ETSI Next Generation Networks (NGN), along with their applicability, which is limited to particular environments. The P-headers defined in the present Ott Expires January 2008 Page 1 Internet-Draft Service Indication Notification July 2007 document are for the purpose of providing indications and notifications for services used within the ETSI NGN. Table of Contents Status of this Memo.........................................1 Abstract................................................. .1 Table of Contents....................................... ...2 1. Overview............................................ ....3 2. Overall Applicability.............................. .....3 3. Terminology......................................... ....3 4. SIP Private Headers......................................3 4.1 The P-Service-Notification header.......................3 4.2 The P-Service-Indication header ........................4 5. Formal Syntax...................................... .....5 5.1 P-Service-Notification header syntax....................5 5.2 P-Service-Indication header syntax......................6 5.3 Table of new headers....................................6 6. Security Considerations..................................6 6.1 P-Service-Notification header...........................6 6.2 P-Service-Indication header.............................7 7. IANA Considerations......................................7 8. References.......................................... ....7 8.1 Normative References....................................7 8.2 Informative References..................................7 9. Authors' Addresses.......................................8 10. Acknowledgments.........................................8 Full Copyright Statement....................................8 Intellectual Property.......................................8 Acknowledgment........................................ .....9 Ott Expires January, 2008 Page 2 1. Overview The European Telecommunications Standards Institute (ETSI) Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN) is defining the release 2 of the TISPAN Next Generation Network (NGN) aiming at the creation of a multimedia fixed network. Generally NGN is based on the 3rd Generation mobile Partnership Project (3GPP) IP Multimedia Subsystem (IMS) Release 7 with additions required to support the fixed access. While ETSI is committed to the creation of new multimedia applications and services, the importance of providing support to existing Integrated Services Digital Network and Public Switched Telephone Network (ISDN/PSTN) supplementary services has also been acknowledged. 2. Overall Applicability The SIP extensions specified in this document make certain assumptions regarding network topology, linkage between SIP and lower layers, and the availability of transitive trust. These assumptions are generally NOT APPLICABLE in the Internet as a whole. The mechanisms specified here were designed to satisfy service specific requirements specified in the release 2 of the TISPAN Next Generation Network (NGN) on SIP [4] for which either no general-purpose solution was planned, where insufficient operational experience was available to understand if a general solution is needed, or where a more general solution is not yet mature. For more details about the assumptions made about these extensions, consult the Applicability subsection for each extension. 3. Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",and "OPTIONAL" are to be interpreted as described in RFC 2119 [9] and indicate requirement levels for compliant implementations. 4. SIP Private Headers 4.1 The P-Service-Notification header This extension allows an entity to send a notification about service specific information to a user. The P-Service-Notification header can be used in SIP requests as well as in responses. This requirement is stated in the TISPAN requirements on SIP [2]. Ott Expires January, 2008 Page 3 Internet-Draft Service Indication Notification July 2007 A typical deployment situation occurs when a SIP request arrives at the UAS and a service conditioned notification needs to be sent back to the UAC. An example for this is when an INVITE request arrives at a callee who is already involved in a call, and the callee wants to inform the caller that this call is a waiting call. 4.1.1 Applicability statement for the P-Service-Notification header The P-Service-Notification is applicable when an entity needs to notify an UA about the status of a service applied by this entity. 4.1.2 Usage of the P-Service-Notification header The P-Service-Notification header field provides an UA with the status of a service of that moment when the information is sent. This information is intended to be rendered to the user. 4.1.2.1 Procedures at the UA A UAC MAY insert a P-Service-Notification header field with a value according to the service currently applied in any SIP request or response. A UAS may insert a P-Service-Notification header field with a value according to the service currently applied in any SIP request or response. 4.1.2.2 Procedures at the proxy A proxy may insert a P-Service-Notification header field with a value according to the service currently applied in any SIP request or response. 4.2 The P-Service-Indication header This extension allows an entity to send an indication about service specific proceeding required for the applied service to a UA or a proxy. The P-Service-Indication header can be used in SIP requests as well as in responses. This requirement is stated in the TISPAN requirements on SIP [2]. A typical deployment situation occurs when a SIP request arrives at a proxy and an indication for a service specific proceeding of this request needs to be send to the UA. An example for this is when an INVITE request arrives at a proxy with the function of an application server that is in control of network resources and needs to indicate to the callee that he should release consumed resources before accepting this call. 4.2.1 Applicability statement for the P-Service-Indication header Ott Expires January 2008 Page 4 Internet-Draft Service Indication Notification July 2007 The P-Service-Indication header is applicable when an entity needs to indicate a service specific proceeding of a request or a response to an UA or a proxy. 4.2.2 Usage of the P-Service-Indication header The P-Service-Indication header field provides an UA or a proxy with an indication how to proceed the SIP request or response in the context of a specific service. 4.2.2.1 Procedures at the UA A UAC MAY insert a P-Service-Indication header field with a value according to the service currently applied in any SIP request or response. A UAS may insert a P-Service-Indication header field with a value according to the service currently applied in any SIP request or response. 4.2.2.2 Procedures at the proxy A proxy may insert a P-Service-Indication header field with a value according to the service currently applied in any SIP request or response. 5. Formal Syntax All of the mechanisms specified in this document are described in both prose and an augmented Backus-Naur Form (BNF) defined in RFC 2234 [3]. Further, several BNF definitions are inherited from SIP and are not repeated here. Implementers need to be familiar with the notation and contents of SIP [1] and RFC 2234 [3] to understand this document. 5.1 P-Service-Notification header syntax The following summarizes the syntax of the P-Service-Notification, based upon the standard SIP syntax [RFC 3261] P-Service-Notification = "P-Service-Notification" HCOLON notification notification = "user-suspended" /"user-resumed" / "conference-established" / "conference-disconnected" / "other-party-added" / "isolated" / "reattached" / "other-party-isolated" / "other-party-reattached" / Ott Expires January 2008 Page 5 Internet-Draft Service Indication Notification July 2007 "other-party-split" / "other-party-disconnected" / "conference-floating" / "call-is-a-waiting call" / "diversion-activated" / "call-transfer-alerting" / "call-transfer-active" / "remote-hold" / "remote-retrieval" / "call-is-diverting" / TOKEN 5.2 P-Service-Indication header syntax The following summarizes the syntax of the P-Service-Indication, based upon the standard SIP syntax [RFC 3261] P-Service-Indication = "P-Service-Indication" HCOLON indication Indication = "CW" /"CCBS" / "CCNR" / TOKEN 5.3 Table of new headers Table 1 extends the headers defined in this document to Table 2 in SIP [1], section 7.1 of the SIP-specific event notification [6], tables 1 and 2 in the SIP INFO method [8], tables 1 and 2 in Reliability of provisional responses in SIP [7], tables 1 and 2 in the SIP UPDATE method [9], tables 1 and 2 in the SIP extension for Instant Messaging [10], and table 1 in the SIP REFER method [11]: Header field where proxy ACK BYE CAN INV OPT REG ___________________________________________________________ P-Service-Notification amdr - - - o - - P-Service-Indication amdr - - - o - - Header field SUB NOT PRA INF UPD MSG REF ___________________________________________________________ P-Service-Notification o o - o o - o P-Service-Indication o o - o o - o Table 1: Header field support 6. Security Considerations 6.1 P-Service-Notification header The information returned in the P-Service-Notification header is not viewed as particularly sensitive. Rather, it is simply informational in nature. If end-to-end protection is not used at Ott Expires January 2008 Page 6 Internet-Draft Service Indication Notification July 2007 the SIP layer, it is possible for proxies to modify the contents of the header value. This attack, while potentially annoying, should not have significant impacts. 6.2 P-Service-Indication header The information returned in the P-Service-Indication header is viewed as particularly sensitive. An indication is sensitive, potentially private, information. Therefore, indications SHOULD be sent in such a way to ensure confidentiality, message integrity and verification of subscriber identity, such as sending indications using a SIPS URL. 7. IANA Considerations This document defines several private SIP extension header fields (beginning with the prefix "P-"). These extension headers have been included in the registry of SIP header fields defined in SIP [1]. Expert review is required for this process by the SIP Working Group. The following extensions are registered as private extension header fields: RFC Number: RFCxxx Header Field Name: P-Service-Notification Compact Form: none RFC Number: RFCxxx Header Field Name: P-Service-Indication Compact Form: none 8. References 8.1 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. 8.2 Informative References [2] Jesske, R., "Analysis of the Input Requirements for the Session Initiation Protocol (SIP) in support for the European Telecommunications Standards Institute (ETSI) Next Generation Networks (NGN) simulation service", draft-jesske-sipping-tispan-analysis-04 (work in progress), December 2007. Ott Expires January 2008 Page 7 Internet-Draft Service Indication Notification July 2007 9. Authors' Addresses Gerhard Ott Deutsche Telekom Hansastrasse 39 90441 Nuernberg Germany Email: gerhard.ott@t-com.net Martin Huelsemann Deutsche Telekom Deutsche-Telekom-Allee 1 64307 Darmstadt Germany Email: martin.huelsemann@t-com.net 10. Acknowledgments This draft was motivated based on the requirements in [2]. Full Copyright Statement Copyright (C) The IETF Trust (2007). 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, THE IETF TRUST 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 Ott Expires January 2008 Page 8 Internet-Draft Service Indication Notification July 2007 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). Ott Expires January 2008 Page 9