INTERNET-DRAFT R. Shekh-Yusef Intended Status: Standards Track Avaya Expires: August 11, 2013 M. Barnes Polycom February 7, 2013 Conference Focus Indicating CCMP Support draft-yusef-dispatch-ccmp-indication-02 Abstract The Centralized Conferencing Manipulation Protocol document defines a way for a client to discover a conference control server that supports CCMP. However, it does not define a way for a client involved in a conference to determine if the conference focus supports CCMP. This information would allow a CCMP-enabled client that joins a conference using SIP to also register for the XCON conference event package RFC4575 [RFC 4575] and take advantage of CCMP operations on the conference. This document describes a few options to address the above limitation with the pros and cons for each approach, and recommends two to be used depending on the need of the UA. The first approach uses the Call-Info header and as a result this document updates RFC3261. The second approach defines a new value for the 'purpose' parameter in the 'service-uris' element in the SIP conferencing event package, and as a result this document update RFC4575 [RFC 4575]. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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/1id-abstracts.html Shekh-Yusef & Barnes Expires August 11, 2013 [Page 1] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License Notice Copyright (c) 2013 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 (http://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 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. Shekh-Yusef & Barnes Expires August 11, 2013 [Page 2] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Call-Info . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Service URI purpose . . . . . . . . . . . . . . . . . . . . 5 3 Security Considerations . . . . . . . . . . . . . . . . . . . . 6 4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 4.1 Call-Info Header "purpose" Parameter . . . . . . . . . . . . 6 4.2 URI Purposes Sub-registry . . . . . . . . . . . . . . . . . 6 5 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.1 Normative References . . . . . . . . . . . . . . . . . . . 7 Appendix A. Other Approaches Considered . . . . . . . . . . . . . 8 A.1 Feature Tag . . . . . . . . . . . . . . . . . . . . . . . . 8 A.2 Conference URI purpose . . . . . . . . . . . . . . . . . . . 8 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Shekh-Yusef & Barnes Expires August 11, 2013 [Page 3] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 1 Introduction RFC 5238 [RFC5239] defines a framework for Centralized Conferencing, which allows participants to exchange media in a centralized unicast conference. The framework also outlines a set of conferencing protocols for building advanced conferencing applications. The CCMP protocol RFC 6503 [RFC6503] allows authenticated and authorized users to create, manipulate and delete conference objects. Operations on conferences include adding and removing participants, changing their roles, as well as adding and removing media streams and associated end points. The CCMP protocol defines a way for a client to determine if a conference control server supports CCMP, but it does not define a way for a client to determine if a conference focus supports CCMP. This document defines two mechanisms to address the above limitation. Other mechanisms that we considered are listed in Appendix A. 1.1 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 [RFC2119]. Shekh-Yusef & Barnes Expires August 11, 2013 [Page 4] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 2 Solutions This section defines the mechanisms that can be used to discover that a focus supports CCMP. 2.1 Call-Info This approach uses the Call-Info header in various requests and responses. The Call-Info header consists of two parts: a URI and a parameter. The purpose of the URI is to provide the XCON-URI of the focus, and the purpose of the parameter is to indicate that the focus supports CCMP. While the XCON-URI by itself should be enough to indicate that the focus supports CCMP, the purpose with a value of 'ccmp' provides an easier way for a UA that is not interested in the URI to discover that the focus supports CCMP without parsing the URI. The Call-Info header, with the XCON-URI and the purpose parameter with the 'ccmp' value, can be used with any INVITE request or response and with a response to an OPTIONS request. The following is the updated ABNF for the Call-Info header: Call-Info = "Call-Info" HCOLON info *(COMMA info) info = LAQUOT absoluteURI RAQUOT *( SEMI info-param) info-param = ( "purpose" EQUAL ( "icon" / "info" / "card" / "ccmp" / token ) ) / generic-param 2.2 Service URI purpose This approach defines an additional URI 'purpose' of 'ccmp' associated with a 'service-uris' element in the SIP conferencing event package. The XCON-URI for the conference is included in the 'uri' element, per the following example: XCON:conf1@example.com ccmp Shekh-Yusef & Barnes Expires August 11, 2013 [Page 5] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 3 Security Considerations These proposals introduce no additional security considerations beyond those which are applicable to each of the mechanisms described herein. 4 IANA Considerations This document defines a new value for the "purpose" parameter of the Call-Info header field and adds a new value for the "purpose" in the URI Purposes Sub-registry of the SIP Parameters registry. 4.1 Call-Info Header "purpose" Parameter Predefined Header Field Parameter Name Values Reference --------------- --------------- --------- --------- Call-Info purpose Yes [RFC3261] [RFC5367] [OPEN ISSUE] Currently, there is no parameter registry for the Call Info header "purpose" values. Should a new registry be created for that? 4.2 URI Purposes Sub-registry This specification defines a new "purpose" value of "ccmp" in the URI Purposes Sub-registry in the sip-parameters registry: http://www.iana.org/assignments/sip-parameters/ The new entry in the sub-registry is as follows: Value Description Document ------- ---------------------------------- --------- ccmp The URI can be used to [RFCxxxx] access a conference that supports CCMP. Note to RFC Editor: Please replace RFC XXXX with the RFC number of this specification. Shekh-Yusef & Barnes Expires August 11, 2013 [Page 6] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 5 Acknowledgments The authors would like to thank Alan Johnston, Robert Sparks, and Cullen Jennings for their careful review and feedback. Special thanks to Adam Roach for his thorough review, comments, and suggestions. 6 References 6.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, 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, June 2002. [RFC5239] Barnes, M., Boulton, C., and O. Levin, "A Framework for Centralized Conferencing", RFC 5239, June 2008. [RFC4575] Rosenberg, J., Schulzrinne, H., and O. Levin, Ed., "A Session Initiation Protocol (SIP) Event Package for Conference State", RFC 4575, August 2006. [RFC5239] Barnes, M., Boulton, C., and O. Levin, "A Framework for Centralized Conferencing", RFC 5239, June 2008. [RFC6503] Barnes M., Boulton, C., Romano S P., and Schulzrinne H., "Centralized Conferencing Manipulation Protocol", RFC6503, March 2012. Shekh-Yusef & Barnes Expires August 11, 2013 [Page 7] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 Appendix A. Other Approaches Considered A.1 Feature Tag This approach defines a feature parameter 'ccmp' to express that a SIP dialog belongs to a conference that supports CCMP. The use of feature parameters in Contact header fields to describe the characteristics and capabilities of a UA is described in the User Agent Capabilities document. The focus behavior regarding the handling of the 'ccmp' feature is the same as the handling of the 'isfocus' feature parameter. In session establishment, a focus MUST include the 'ccmp' feature parameter in the Contact header field unless the focus wishes to hide the fact that it is a focus. The pros of this approach is a one step discovery of the focus and its ccmp support, and the fact that it can be used in response to an OPTIONS request, and that it enables the discovery of the ccmp capability by any network element that does not need the conference event package. The cons is the definition of a new feature parameter. A.2 Conference URI purpose Define an additional URI 'purpose' of 'ccmp' associated with a 'confs-uris' element in the SIP conferencing event package. ccmp: Indicates that the conference focus represented by this URI supports ccmp, which allows a client to use the CCMP protocol to manipulate the conference. This URI MUST be an XCON-URI as defined in the xcon-data-model. XCON:conf1@example.com whatever ccmp The pro of the SIP conference event package options is the use of an existing mechanism for extending the field of the or elements. The con is the requirement that the client register for the conference event package. However, given that clients that want to take advantage of CCMP would most likely register for the conference event packages. Shekh-Yusef & Barnes Expires August 11, 2013 [Page 8] INTERNET DRAFT Conference Focus CCMP Support February 7, 2013 Author's Addresses Rifaat Shekh-Yusef Avaya 250 Sidney Street Belleville, Ontario Canada Phone: +1-613-967-5267 Email: rifatyu@avaya.com Mary Barnes Polycom TX US Email: mary.ietf.barnes@gmail.com Shekh-Yusef & Barnes Expires August 11, 2013 [Page 9]