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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC3261' is defined on line 212, but no explicit reference was found in the text == Unused Reference: 'RFC5239' is defined on line 217, but no explicit reference was found in the text == Unused Reference: 'RFC4575' is defined on line 220, but no explicit reference was found in the text == Unused Reference: 'CCMP' is defined on line 224, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. 'CCMP' Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 INTERNET-DRAFT R. Shekh-Yusef 3 Intended Status: Standards Track Avaya 4 Expires: September 13, 2012 M. Barnes 5 Polycom 6 March 12, 2012 8 Conference Focus Indicating CCMP Support 9 draft-yusef-xcon-ccmp-indication-02.txt 11 Abstract 13 The Centralized Conferencing Manipulation Protocol document defines 14 away for a client to discover a conference control server that 15 supports CCMP. However, it does not define a way for a client 16 involved in a conference to determine if the conference focus 17 supports CCMP. This information would allow a CCMP-enabled client 18 that joins a conference using SIP to also register for the XCON 19 conference event package and take advantage of CCMP operations on the 20 conference. 22 This draft describes few options to address the above limitation with 23 the pros and cons for each approach. 25 Status of this Memo 27 This Internet-Draft is submitted to IETF in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF), its areas, and its working groups. Note that 32 other groups may also distribute working documents as 33 Internet-Drafts. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 The list of current Internet-Drafts can be accessed at 41 http://www.ietf.org/1id-abstracts.html 43 The list of Internet-Draft Shadow Directories can be accessed at 44 http://www.ietf.org/shadow.html 46 Copyright and License Notice 48 Copyright (c) 2011 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 Table of Contents 63 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 65 2 Possible Solutions . . . . . . . . . . . . . . . . . . . . . . . 5 66 2.1 Feature Tag . . . . . . . . . . . . . . . . . . . . . . . . 5 67 2.2 OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 5 68 2.3 Conference Event Package . . . . . . . . . . . . . . . . . . 6 69 2.3.1 Service URI purpose . . . . . . . . . . . . . . . . . . 6 70 2.3.2 Conference URI purpose . . . . . . . . . . . . . . . . 6 71 3 Security Considerations . . . . . . . . . . . . . . . . . . . . 7 72 4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 73 5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 74 5.1 Normative References . . . . . . . . . . . . . . . . . . . 7 75 5.2 Informative References . . . . . . . . . . . . . . . . . . 7 76 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 78 1 Introduction 80 RFC 5239 defines a framework for Centralized Conferencing, which 81 allows participants to exchange media in a centralized unicast 82 conference. The framework also outlines a set of conferencing 83 protocols for building advanced conferencing applications. 85 The Centralized Conferencing Manipulation Protocol (CCMP) allows 86 authenticated and authorized users to create, manipulate and delete 87 conference objects. Operations on conferences include adding and 88 removing participants, changing their roles, as well as adding and 89 removing media streams and associated end points. 91 The Centralized Conferencing Manipulation Protocol (CCMP) draft 92 defines a way for a client to determine a conference control server 93 that supports CCMP, but it does not define a way for a client to 94 determine if a conference focus supports CCMP. 96 This draft describes few options to address the above limitation with 97 the pros and cons for each approach. 99 1.1 Terminology 101 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 102 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 103 document are to be interpreted as described in RFC 2119 [RFC2119]. 105 2 Possible Solutions 107 2.1 Feature Tag 109 This approach defines a feature parameter 'ccmp' to express that a 110 SIP dialog belongs to a conference that supports CCMP. The use of 111 feature parameters in Contact header fields to describe the 112 characteristics and capabilities of a UA is described in the User 113 Agent Capabilities document. 115 The focus behavior regarding the handling of the 'ccmp' feature is 116 the same as the handling of the 'isfocus' feature parameter. In 117 session establishment, a focus MUST include the 'ccmp' feature 118 parameter in the Contact header field unless the focus wishes to hide 119 the fact that it is a focus. 121 The pros of this approach is a one step discovery of the focus and 122 its ccmp support, and the fact that it can be used in response to an 123 OPTIONS request, and that it enables the discovery of the ccmp 124 capability by any network element that does not need the conference 125 event package. The cons is the definition of a new feature parameter. 127 2.2 OPTIONS 129 This approach requires the client to send an OPTIONS request to the 130 conference focus to determine if the conference supports CCMP. 132 If the feature tag approach is used, then the 200 OK response to the 133 OPTIONS request MUST include the ccmp feature parameter in the 134 Contact header. 136 Another option is return the Call-Info header with an XCON-URI in the 137 200 OK . 139 The pros of this approach is that it is consistent with SIP in terms 140 of the mechanism by which a UA determines the capabilities of a SIP 141 intermediary, and that it enables the discovery of the ccmp 142 capability by any network element that does not need the conference 143 event package. The cons is that it requires an extra step to 144 determine that a conference focus supports CCMP. 146 2.3 Conference Event Package 148 There are two options that rely on the SIP conference event package 149 defined in RFC 4575: 151 2.3.1 Service URI purpose 153 Define an additional URI 'purpose' of 'ccmp' associated with a 154 'service-uris' element in the SIP conferencing event package. The 155 XCON-URI for the conference is included in the 'uri' element, per the 156 following example: 158 159 160 XCON:conf1@example.com 161 ccmp 162 163 165 2.3.2 Conference URI purpose 167 Define an additional URI 'purpose' of 'ccmp' associated with a 168 'confs-uris' element in the SIP conferencing event package. 170 ccmp: Indicates that the conference focus represented by this URI 171 supports ccmp, which allows a client to use the CCMP protocol to 172 manipulate the conference. This URI MUST be an XCON-URI as defined in 173 the xcon-data-model. 175 176 177 XCON:conf1@example.com 178 whatever 179 ccmp 180 181 183 The pro of the SIP conference event package options is the use of an 184 existing mechanism for extending the field of the or elements. The con is the requirement that the 186 client register for the conference event package. However, given 187 that clients that want to take advantage of CCMP would most likely 188 register for the conference event packages. 190 3 Security Considerations 192 These proposal introduce no additional security considerations beyond 193 those which are applicable to each of the mechanisms described 194 herein. 196 4 IANA Considerations 198 200 5 Acknowledgments 202 The authers would like to thanks Alan Johnston and Robert Sparks for 203 their careful review and feedback. 205 6 References 207 6.1 Normative References 209 [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate 210 Requirement Levels", BCP 14, RFC 2119, March 1997. 212 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 213 A., Peterson, J., Sparks, R., Handley, M., and E. 214 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 215 June 2002. 217 [RFC5239] Barnes, M., Boulton, C., and O. Levin, "A Framework for 218 Centralized Conferencing", RFC 5239, June 2008. 220 [RFC4575] Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session 221 Initiation Protocol (SIP) Event Package for Conference 222 State", RFC 4575, August 2006. 224 [CCMP] Barnes M., Boulton, C., Romano S P., and Schulzrinne H., 225 "Centralized Conferencing Manipulation Protocol", Work in 226 Progress, October 2010. 228 6.2 Informative References 229 Author's Addresses 231 Rifaat Shekh-Yusef 232 Avaya 233 250 Sidney Street 234 Belleville, Ontario 235 Canada 237 Phone: +1-613-967-5267 238 Email: rifatyu@avaya.com 240 Mary Barnes 241 Polycom 242 TX 243 US 245 Email: mary.ietf.barnes@gmail.com