MMUSIC James Polk Internet-Draft Subha Dhesikan Expires: September 7, 2006 Cisco Systems Gonzalo Camarillo Ericsson March 6, 2006 An Identification of QoS Mechanism for Preconditions draft-polk-mmusic-qos-mechanism-identification-01.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 September 7, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract The offer/answer model for SDP assumes that endpoints establish, somehow, the QoS (Quality of Service) required for the media streams they establish. Endpoints in closed environments typically agree out of band (e.g., using configuration information) which QoS mechanism to use. However, in the Internet, there is more than one QoS service available. Consequently, there is a need for a mechanism to James Polk, et al. Expires September 7, 2006 [Page 1] Internet-Draft An Identification QoS Mechanism March 2006 negotiate which QoS mechanism to use for a particular media stream. This document defines such a mechanism. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Definition of the qos-selection Attribute . . . . . . . . . . . 3 4. Offer/answer Behavior . . . . . . . . . . . . . . . . . . . . . 4 5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9.1. Normative References . . . . . . . . . . . . . . . . . . . 5 9.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 8 James Polk, et al. Expires September 7, 2006 [Page 2] Internet-Draft An Identification QoS Mechanism March 2006 1. Introduction The offer/answer model [1] for SDP [2] does not provide any mechanism for endpoints to negotiate the QoS mechanism to be used for a particular media stream. Even when QoS preconditions [9] are used, the choice of the QoS mechanism is left unspecified, up to the endpoints. Endpoints that support more than one QoS mechanism need a way to negotiate which one to use for a particular media stream. Examples of QoS mechanisms are RSVP (Resource Reservation Protocol), initially defined in [3], and NSIS (Next Steps in Signaling), defined in at least 3 documents: [4], [5] and [6]. This document defines a mechanism that allows endpoints to negotiate the QoS mechanism to be used for a particular media stream. Section 3 defines the 'qos-selection' SDP attribute, Section 4 specifies the use of the 'qos-selection' attribute with the offer/ answer model, and Section 5 provides examples of offer/answer exchanges that use the 'qos-selection' attribute. 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 [7] and indicate requirement levels for compliant implementations. 3. Definition of the qos-selection Attribute This document defines the 'qos-selection' session and media-level SDP [2] attribute. The following is its ABNF syntax [8], which is based on the SDP [2] grammar: attribute = qos-selection-attr qos-selection-attr = "qos-selection" ":" qos-mech SP direction qos-mech = rsvp / nsis / extension-mech extension-mech = token direction = send / recv / sendrecv Figure 1: Syntax of the qos-selection attribute James Polk, et al. Expires September 7, 2006 [Page 3] Internet-Draft An Identification QoS Mechanism March 2006 The 'qos-mech' token identifies a QoS mechanism that is supported by the entity generating the session description. The 'direction' token indicates in which direction can be used to reserve resources that QoS mechanism. send: QoS can be reserved for traffic sent by the entity generating the session description. recv: QoS can be reserved for traffic received by the entity generating the session description. sendrecv: QoS can be reserved for traffic in both directions. An SDP session description MAY contain more than one 'qos-selection' attribute. The following is an example of an 'm' line with two 'qos-selection' attributes: m=audio 50000 RTP/AVP 0 a=qos-selection:rsvp sendrecv a=qos-selection:nsis sendrecv 4. Offer/answer Behavior Offerers include a 'qos-selection' attribute per QoS mechanism they are willing to use for the media stream. Each 'qos-selection' attribute includes the direction in which the mechanism can be used. On receiving an offer with 'qos-selection' attributes, the answerer chooses a QoS mechanism from the 'qos-selection' attributes for each direction where QoS is needed. That is, if QoS is needed in both directions (sendrecv), the answerer can choose the same QoS mechanism for both directions or a different one for each direction. The answerer MUST add 'qos-selection' attributes for each QoS mechanisms it has chosen to use. If the answerer lists two QoS mechanisms for a given direction, both mechanisms will be used. Note that endpoints negotiate in which direction QoS is needed using other mechanisms, such as preconditions [9]. Endpoints may also use other mechanisms to negotiate, if needed, the parameters to use with a given QoS mechanism (e.g., bandwidth to be reserved). 5. Example The following is an offer/answer exchange between two endpoints using James Polk, et al. Expires September 7, 2006 [Page 4] Internet-Draft An Identification QoS Mechanism March 2006 the 'qos-selection' attribute. Parts of the session descriptions are ommitted for clarity purposes. The offerer generates the following session description listing both RSVP and NSIS for both directions: m=audio 50000 RTP/AVP 0 a=qos-selection:rsvp sendrecv a=qos-selection:nsis sendrecv The answerer chooses to use RSVP in both directions and, consequently, returns the following session description: m=audio 55000 RTP/AVP 0 a=qos-selection:rsvp sendrecv 6. IANA Considerations TBD. 7. Security Considerations TBD. 8. Acknowledgements To Dave Oran for his help in forming this effort. 9. References 9.1. Normative References [1] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. [2] Handley, M., "SDP: Session Description Protocol", draft-ietf-mmusic-sdp-new-26 (work in progress), January 2006. [3] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. James Polk, et al. Expires September 7, 2006 [Page 5] Internet-Draft An Identification QoS Mechanism March 2006 [4] "GIMPS: General Internet Messaging Protocol for Signaling", draft-draft-ietf-nsis-ntlp-00 (work in progress), October 2003. [5] Hancock, R., Karagiannis, G., Loughney, J., and S. Van den Bosch, "Next Steps in Signaling (NSIS): Framework", RFC 4080, June 2005. [6] Chaskar, H., "Requirements of a QoS Solution for Mobile IP", draft-ietf-nsis-qos-requirements-01 (work in progress), June 2003. [7] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [8] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005. 9.2. Informative References [9] Camarillo, G., Marshall, W., and J. Rosenberg, "Integration of Resource Management and Session Initiation Protocol (SIP)", RFC 3312, October 2002. James Polk, et al. Expires September 7, 2006 [Page 6] Internet-Draft An Identification QoS Mechanism March 2006 Authors' Addresses James M. Polk Cisco Systems 3913 Treemont Circle Colleyville, Texas 76034 USA Phone: +1-817-271-3552 Email: jmpolk@cisco.com Subha Dhesikan Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 USA Email: sdhesika@cisco.com Gonzalo Camarillo Ericsson Hirsalantie 11 Jorvas 02420 Finland Email: Gonzalo.Camarillo@ericsson.com James Polk, et al. Expires September 7, 2006 [Page 7] Internet-Draft An Identification QoS Mechanism March 2006 Intellectual Property Statement 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. Disclaimer of Validity 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. 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. James Polk, et al. Expires September 7, 2006 [Page 8]