Diff: draft-ietf-mmusic-fid-05.txt - draft-ietf-mmusic-fid-06.txt

	draft-ietf-mmusic-fid-05.txt	draft-ietf-mmusic-fid-06.txt

	Internet Engineering Task Force Gonzalo Camarillo	Internet Engineering Task Force Gonzalo Camarillo
	Internet draft Jan Holler	Internet draft Jan Holler
	Goran AP Eriksson	Goran AP Eriksson
	Ericsson	Ericsson

	Henning Schulzrinne	Henning Schulzrinne
	Columbia University	Columbia University


	September 2001	February 2002
	Expires March 2002	Expires August 2002
	<draft-ietf-mmusic-fid-05.txt>	<draft-ietf-mmusic-fid-06.txt>

	Grouping of media lines in SDP	Grouping of media lines in SDP

	Status of this Memo	Status of this Memo

	This document is an Internet-Draft and is in full conformance with	This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.	all provisions of Section 10 of RFC2026.

	Internet-Drafts are working documents of the Internet Engineering	Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that	Task Force (IETF), its areas, and its working groups. Note that

	skipping to change at line 75	skipping to change at line 75
	8 Usage of the "group" attribute in SIP.....................11	8 Usage of the "group" attribute in SIP.....................11
	8.1 Mid value in responses....................................11	8.1 Mid value in responses....................................11
	8.1.1 Example...................................................12	8.1.1 Example...................................................12
	8.2 Group value in responses..................................12	8.2 Group value in responses..................................12
	8.2.1 Example...................................................13	8.2.1 Example...................................................13
	8.3 Capability negotiation....................................14	8.3 Capability negotiation....................................14
	8.3.1 Example...................................................14	8.3.1 Example...................................................14
	8.4 Backward compatibility....................................14	8.4 Backward compatibility....................................14
	8.4.1 Client does not support "group"...........................15	8.4.1 Client does not support "group"...........................15
	8.4.2 Server does not support "group"...........................15	8.4.2 Server does not support "group"...........................15

	9 IANA considerations.......................................15	9 Security considerations...................................15
	10 Acknowledgements..........................................16	10 IANA considerations.......................................16
	11 References................................................16	11 Acknowledgements..........................................16
	12 Authors³ Addresses........................................16	12 References................................................16
		13 Authors³ Addresses........................................16

	1 Introduction	1 Introduction

	An SDP session description typically contains a number (one or more)	An SDP session description typically contains a number (one or more)
	of media lines - they are commonly known as "m" lines. When a	of media lines - they are commonly known as "m" lines. When a
	session description contains more than one "m" line, SDP does not	session description contains more than one "m" line, SDP does not
	provide any means to express a particular relationship between two	provide any means to express a particular relationship between two
	or more of them. When an application receives an SDP session	or more of them. When an application receives an SDP session
	description with more than one "m" line it is up to the application	description with more than one "m" line it is up to the application
	what to do with them. SDP does not carry any information about	what to do with them. SDP does not carry any information about

	skipping to change at line 794	skipping to change at line 795
	incoming RTP sessions, which is the correct behavior.	incoming RTP sessions, which is the correct behavior.

	An implementation might also decide to refuse the request (e.g. 488	An implementation might also decide to refuse the request (e.g. 488
	Not acceptable here or 606 Not Acceptable) because it contains	Not acceptable here or 606 Not Acceptable) because it contains
	several "m" lines. In this case, the server does not support the	several "m" lines. In this case, the server does not support the
	type of session that the caller wanted to establish. In case the	type of session that the caller wanted to establish. In case the
	client is willing to establish a simpler session anyway, he SHOULD	client is willing to establish a simpler session anyway, he SHOULD
	re-try the request without "group" attribute and only one "m" line	re-try the request without "group" attribute and only one "m" line
	per flow.	per flow.


	9. IANA considerations	9. Security considerations

		Using the "group" parameter with FID semantics an entity that
		managed to modify the session descriptions exchanged between the
		participants to establish a multimedia session could force the
		participants to send a copy of the media to any particular
		destination.

		Integrity mechanism provided by protocols used to exchange session
		descriptions and media encryption can be used to prevent this
		attack.

		Camarillo/Holler/Eriksson/Schulzrinne 15
		Grouping of media lines in SDP

		10. IANA considerations

	This document defines two SDP attributes: "mid" and "group".	This document defines two SDP attributes: "mid" and "group".

	The "mid" attribute is used to identify media streams within a	The "mid" attribute is used to identify media streams within a
	session description and its format is defined in Section 3.	session description and its format is defined in Section 3.

	The "group" attribute is used for grouping together different media	The "group" attribute is used for grouping together different media
	streams and its format is defined in Section 4.	streams and its format is defined in Section 4.

	Section 4 also defines two standard semantics related to the "group"	Section 4 also defines two standard semantics related to the "group"
	attribute: LS (Lip Synchronization) and FID (Flow Identification).	attribute: LS (Lip Synchronization) and FID (Flow Identification).
	If in the future it was needed to standardize further semantics they	If in the future it was needed to standardize further semantics they
	would need to be defined in a standards track document.	would need to be defined in a standards track document.


	Camarillo/Holler/Eriksson/Schulzrinne 15	11. Acknowledgments
	Grouping of media lines in SDP

	10. Acknowledgments

	The authors would like to thank Jonathan Rosenberg, Adam Roach, Orit	The authors would like to thank Jonathan Rosenberg, Adam Roach, Orit
	Levin and Joerg Ott for their feedback on this document.	Levin and Joerg Ott for their feedback on this document.


	11. References	12. References

	[1] S. Bradner, "Key words for use in RFCs to Indicate Requirement	[1] S. Bradner, "Key words for use in RFCs to Indicate Requirement
	Levels", RFC 2119, IETF; March 1997.	Levels", RFC 2119, IETF; March 1997.

	[2] M. Handley/V. Jacobson, "SDP: Session Description Protocol", RFC	[2] M. Handley/V. Jacobson, "SDP: Session Description Protocol", RFC
	2327, IETF; April 1998.	2327, IETF; April 1998.

	[3] H. Schulzrinne/A. Rao/R. Lanphier, "Real Time Streaming Protocol	[3] H. Schulzrinne/A. Rao/R. Lanphier, "Real Time Streaming Protocol
	(RTSP)", RFC 2326, IETF; April 1998.	(RTSP)", RFC 2326, IETF; April 1998.

	[4] H. Schulzrinne/S. Casner/R. Frederick/V. Jacobson, "RTP: A	[4] H. Schulzrinne/S. Casner/R. Frederick/V. Jacobson, "RTP: A
	Transport Protocol for Real-Time Applications", RFC 1889, IETF;	Transport Protocol for Real-Time Applications", RFC 1889, IETF;
	January 1996.	January 1996.

	[5] M. Handley/H. Schulzrinne/E. Schooler/J. Rosenberg, "SIP:	[5] M. Handley/H. Schulzrinne/E. Schooler/J. Rosenberg, "SIP:
	Session Initiation Protocol", RFC 2543, IETF; Mach 1999.	Session Initiation Protocol", RFC 2543, IETF; Mach 1999.

	[6] H. Schulzrinne/S. Petrack, "RTP Payload for DTMF Digits,	[6] H. Schulzrinne/S. Petrack, "RTP Payload for DTMF Digits,
	Telephony Tones and Telephony Signals", RFC 2833, IETF; May 2000.	Telephony Tones and Telephony Signals", RFC 2833, IETF; May 2000.


	12. Authors³ Addresses	13. Authors³ Addresses

	Gonzalo Camarillo	Gonzalo Camarillo
	Ericsson	Ericsson
	Advanced Signalling Research Lab.	Advanced Signalling Research Lab.
	FIN-02420 Jorvas	FIN-02420 Jorvas
	Finland	Finland
	Phone: +358 9 299 3371	Phone: +358 9 299 3371
	Fax: +358 9 299 3052	Fax: +358 9 299 3052
	Email: Gonzalo.Camarillo@ericsson.com	Email: Gonzalo.Camarillo@ericsson.com


		Camarillo/Holler/Eriksson/Schulzrinne 16
		Grouping of media lines in SDP

	Jan Holler	Jan Holler
	Ericsson Research	Ericsson Research
	S-16480 Stockholm	S-16480 Stockholm
	Sweden	Sweden
	Phone: +46 8 58532845	Phone: +46 8 58532845
	Fax: +46 8 4047020	Fax: +46 8 4047020
	Email: Jan.Holler@era.ericsson.se	Email: Jan.Holler@era.ericsson.se

	Goran AP Eriksson	Goran AP Eriksson
	Ericsson Research	Ericsson Research
	S-16480 Stockholm	S-16480 Stockholm
	Sweden	Sweden
	Phone: +46 8 58531762	Phone: +46 8 58531762
	Fax: +46 8 4047020	Fax: +46 8 4047020
	Email: Goran.AP.Eriksson@era.ericsson.se	Email: Goran.AP.Eriksson@era.ericsson.se


	Camarillo/Holler/Eriksson/Schulzrinne 16
	Grouping of media lines in SDP

	Henning Schulzrinne	Henning Schulzrinne
	Dept. of Computer Science	Dept. of Computer Science
	Columbia University	Columbia University
	1214 Amsterdam Avenue	1214 Amsterdam Avenue
	New York, NY 10027	New York, NY 10027
	USA	USA
	Email: schulzrinne@cs.columbia.edu	Email: schulzrinne@cs.columbia.edu


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	Camarillo/Holler/Eriksson/Schulzrinne 17	Camarillo/Holler/Eriksson/Schulzrinne 17

		Grouping of media lines in SDP

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