MMUSIC Working Group G. Camarillo Internet-Draft Ericsson Expires: April 15, 2005 October 15, 2004 Session Description Protocol (SDP) Format for Binary Floor Control Protocol (BFCP) Streams draft-camarillo-mmusic-sdp-bfcp-00.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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 15, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract This document specifies how to describe BFCP streams in a SDP session description. User agents using the offer/answer model to establish BFCP streams use this format in their offers and their answers. Camarillo Expires April 15, 2005 [Page 1] Internet-Draft BFCP October 2004 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Fields in the m Line . . . . . . . . . . . . . . . . . . . . . 3 4. The confid and userid SDP Parameters . . . . . . . . . . . . . 4 5. The k line . . . . . . . . . . . . . . . . . . . . . . . . . . 4 6. TCP Connection Management . . . . . . . . . . . . . . . . . . 4 7. Association between Streams and Floors . . . . . . . . . . . . 5 8. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9. Security Considerations . . . . . . . . . . . . . . . . . . . 6 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 10.1 SDP Attributes Registration . . . . . . . . . . . . . . . 6 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 12.1 Normative References . . . . . . . . . . . . . . . . . . . . 6 12.2 Informational References . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . 8 Camarillo Expires April 15, 2005 [Page 2] Internet-Draft BFCP October 2004 1. Introduction As discussed in the BFCP specification [5], a given BFCP client needs a set of data in order to establish a BFCP connection to a floor control server. These data include the transport address of the server, the conference identifier, and the user identifier. Clients can obtain this information in different ways, one of them consisting of using an offer/answer [3] exchange. This document specifies how to encode this information in the SDP session descriptions which are part of an offer/answer exchange. User agents typically use the offer/answer model to establish a number of media streams of different types. Following this model, a BFCP connection is described as any other media stream by using an SDP 'm' line, possibly followed by a number of attributes encoded in 'a' lines. 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 [1] and indicate requirement levels for compliant implementations. 3. Fields in the m Line According to RFC 2327 [2], the 'm'line format is the following: m= The media field MUST have a value of "application". The port field is not used by BFCP, and MAY be set to any value chosen by the endpoint. A port field value of zero has the standard SDP meaning (i.e., rejection of the media stream). The port field is set following the rules in [4]. Depending on the value of the setup attribute (disccused in Section 6), the port field contains the port the remote endpoint will initiate its TCP connection to, or is irrelevant (i.e., the endpoint will initiate the connection towards the remote endpoint) and should be set to a value of 9, which is the discard port. Since BFCP only runs on top of TCP, the port is always a TCP port. We define two new values for the transport field: TCP/BFCP and TCP/ TLS/BFCP. Camarillo Expires April 15, 2005 [Page 3] Internet-Draft BFCP October 2004 The fmt (format) list is ignored for BFCP. The fmt list of BFCP m lines SHOULD contain a single "*" character. The following is an example of an m line for a BFCP connection: m=application 20000 TCP/BFCP * 4. The confid and userid SDP Parameters We define the confid and the userid SDP media-level attributes. Their syntax is: confid-attribute = "a=confid: " conference-id conference-id = token userid-attribute = "a=userid: " user-id user-id = token The confid and the userid attributes carry the integer representation of a conference ID and a user ID respectively. Endpoints which use the offer/answer model to establish BFCP connections MUST support the confid and the userid attributes. A floor control server acting as an offerer or as an answerers SHOULD include these attributes in its session descriptions. 5. The k line If the offer/answer exchange is encrypted and integrity protected, the offerer MAY use an SDP 'k' line to provide the answerer with a shared secret to be used to calculate the value of the DIGEST TLVs. The following is an example of a 'k' line: k=base64:c2hhcmVkLXNlY3JldA== 6. TCP Connection Management The management of the TCP connection used to transport BFCP is performed using the setup and 'connection' attributes as defined in [4]. The setup attribute indicates which of the endpoints (client or floor control server) initiates the TCP connection. The 'connection' Camarillo Expires April 15, 2005 [Page 4] Internet-Draft BFCP October 2004 attribute handles TCP connection reestablishment. Editor's note: need to address loss and re-establishment of TCP connections. 7. Association between Streams and Floors We define the floorid SDP media-level attribute. Its syntax is: floor-id-attribute = "a=floorid:" token " mstream:" 1*(token) The floorid attribute is used in BFCP m lines and associates a floor ID with a media stream. The token representing the floor ID is the integer representation of the 16-bit floorid to be used in BFCP. The token representing the media stream is a pointer to the media stream, which is identified by an SDP label attribute [6] Endpoints which use the offer/answer model to establish BFCP connections MUST support the floorid and the label attributes. A floor control server acting as an offerer or as an answerers SHOULD include these attributes in its session descriptions. 8. Example The following is an example of an offer sent by a conference server to a user. For the purpose of brevity, the main portion of the session description is omitted in the examples, which only show m= lines and their attributes. m=application 20000 TCP/BFCP * k=base64:c2hhcmVkLXNlY3JldA== a=setup:passive a=connection:new a=confid:4321 a=userid:1234 a=floorid:1 m-stream:10 a=floorid:2 m-stream:11 m=audio 20000 RTP/AVP 0 a=label:10 m=video 30000 RTP/AVP 31 a=label:11 The following is the answer returned by the user. Camarillo Expires April 15, 2005 [Page 5] Internet-Draft BFCP October 2004 m=application 9 TCP/BFCP * a=setup:active a=connection:new m=audio 25000 RTP/AVP 0 m=video 35000 RTP/AVP 31 9. Security Considerations TBD. 10. IANA Considerations TBD. 10.1 SDP Attributes Registration TBD: 11. Acknowledgments Joerg Ott, Keith Drage, and Alan Johnston provided useful ideas for this document. 12. References 12.1 Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998. [3] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. [4] Yon, D., "Connection-Oriented Media Transport in the Session Description Protocol (SDP)", draft-ietf-mmusic-sdp-comedia-08 (work in progress), July 2004. [5] Camarillo, G., "The Binary Floor Control Protocol (BFCP)", draft-ietf-xcon-bfcp-01 (work in progress), August 2004. [6] Levin, O. and G. Camarillo, "The SDP (Session Description Protocol) Label Attribute", draft-levin-mmmusic-sdp-media-label-00 (work in progress), July 2004. Camarillo Expires April 15, 2005 [Page 6] Internet-Draft BFCP October 2004 12.2 Informational References Author's Address Gonzalo Camarillo Ericsson Hirsalantie 11 Jorvas 02420 Finland EMail: Gonzalo.Camarillo@ericsson.com Camarillo Expires April 15, 2005 [Page 7] Internet-Draft BFCP October 2004 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. 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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 (2004). 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. Camarillo Expires April 15, 2005 [Page 8]