draft-ietf-mmusic-data-channel-sdpneg-26.txt		draft-ietf-mmusic-data-channel-sdpneg-27.txt
	MMUSIC K. Drage		MMUSIC K. Drage
	Internet-Draft Unaffiliated		Internet-Draft Unaffiliated
	Intended status: Standards Track M. Makaraju		Intended status: Standards Track M. Makaraju
	Expires: October 25, 2019 Nokia		Expires: October 31, 2019 Nokia
	R. Ejzak		R. Ejzak
	J. Marcon		J. Marcon
	Unaffiliated		Unaffiliated
	R. Even, Ed.		R. Even, Ed.
	Huawei		Huawei
	April 23, 2019		April 29, 2019
	SDP-based Data Channel Negotiation		SDP-based Data Channel Negotiation
	draft-ietf-mmusic-data-channel-sdpneg-26		draft-ietf-mmusic-data-channel-sdpneg-27
	Abstract		Abstract
	Data channel setup can be done using either the in-band Data Channel		Data channel setup can be done using either the in-band Data Channel
	Establishment Protocol (DCEP) or using some out-of-band non-DCEP		Establishment Protocol (DCEP) or using some out-of-band non-DCEP
	protocol. This document specifies how the SDP (Session Description		protocol. This document specifies how the SDP (Session Description
	Protocol) offer/answer exchange can be used to achieve an out-of-band		Protocol) offer/answer exchange can be used to achieve an out-of-band
	non-DCEP negotiation for establishing a data channel.		non-DCEP negotiation for establishing a data channel.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 40 ¶		skipping to change at page 1, line 40 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on October 25, 2019.		This Internet-Draft will expire on October 31, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 6, line 5 ¶		skipping to change at page 6, line 4 ¶
	as specified in [RFC4960].		as specified in [RFC4960].
	Stream identifier: The identifier of the outbound and inbound SCTP		Stream identifier: The identifier of the outbound and inbound SCTP
	streams composing a data channel.		streams composing a data channel.
	4. Applicability Statement		4. Applicability Statement
	The mechanism in this document only applies to the Session		The mechanism in this document only applies to the Session
	Description Protocol (SDP) [I-D.ietf-mmusic-rfc4566bis] when used		Description Protocol (SDP) [I-D.ietf-mmusic-rfc4566bis] when used
	together with the SDP offer/answer mechanism [RFC3264]. Declarative		together with the SDP offer/answer mechanism [RFC3264]. Declarative
	usage of SDP is out of scope of this document, and is thus undefined.		usage of SDP is out of scope for this document, and is thus
			undefined.
	5. SDP Data Channel Attributes		5. SDP Data Channel Attributes
	This section defines two new SDP media-level attributes that can be		This section defines two new SDP media-level attributes that can be
	used together with the SDP Offer/Answer mechanism to negotiate data		used together with the SDP Offer/Answer mechanism to negotiate data
	channel-specific and subprotocol-specific parameters without the		channel-specific and subprotocol-specific parameters without the
	usage of DCEP [I-D.ietf-rtcweb-data-protocol]. The first attribute		usage of DCEP [I-D.ietf-rtcweb-data-protocol]. The first attribute
	provides for negotiation of channel-specific parameters. The second		provides for negotiation of channel-specific parameters. The second
	attribute provides for negotiation of subprotocol-specific		attribute provides for negotiation of subprotocol-specific
	parameters.		parameters.
	skipping to change at page 14, line 28 ¶		skipping to change at page 14, line 28 ¶
	ordered=true;max-time=<lifetime in milliseconds>		ordered=true;max-time=<lifetime in milliseconds>
	DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED		DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED
	ordered=false;max-time=<lifetime in milliseconds>		ordered=false;max-time=<lifetime in milliseconds>
	By definition max-retr and max-time are mutually exclusive, so both		By definition max-retr and max-time are mutually exclusive, so both
	MUST NOT be present in the "a=dcmap:" attribute line. If an SDP		MUST NOT be present in the "a=dcmap:" attribute line. If an SDP
	offer contains both of these parameters then the receiver of such an		offer contains both of these parameters then the receiver of such an
	SDP offer MUST reject the SDP offer. If an SDP answer contains both		SDP offer MUST reject the SDP offer. If an SDP answer contains both
	of these parameters then the offerer MUST treat the associated SDP		of these parameters then the offerer MUST treat the associated SDP
	offer/answer failed.		offer/answer as failed.
	6.3. Generating the Initial Offer for A Data Channel		6.3. Generating the Initial Offer for A Data Channel
	When an offerer sends an initial offer, in order to negotiate an SCTP		When an offerer sends an initial offer, in order to negotiate an SCTP
	stream for a data channel, the offerer:		stream for a data channel, the offerer:
	o SHALL include an SDP dcmap attribute (Section 5 and Section 6.2)		o SHALL include an SDP dcmap attribute (Section 5 and Section 6.2)
	associated with the data channel in the "m=" section representing		associated with the data channel in the "m=" section representing
	the SCTP association used to realize the data channel; and		the SCTP association used to realize the data channel; and
	skipping to change at page 15, line 22 ¶		skipping to change at page 15, line 22 ¶
	An offerer receiving an SDP answer performs the following:		An offerer receiving an SDP answer performs the following:
	o SHALL close any created data channels as described in		o SHALL close any created data channels as described in
	Section 6.6.1 for which the expected "a=dcmap:" attributes are not		Section 6.6.1 for which the expected "a=dcmap:" attributes are not
	present in the SDP answer. If the SDP answer has no "a=dcmap"		present in the SDP answer. If the SDP answer has no "a=dcmap"
	attribute either the peer does not support "a=dcmap:" attributes		attribute either the peer does not support "a=dcmap:" attributes
	or it rejected all the data channels. In either case the offerer		or it rejected all the data channels. In either case the offerer
	closes all the SDP offered data channels that were open at the		closes all the SDP offered data channels that were open at the
	time of offer. The DTLS association and SCTP association will		time of offer. The DTLS association and SCTP association will
	still be setup.		still be setup. At this point the offerer may use DCEP
			negotiation [I-D.ietf-rtcweb-data-protocol] to open data channels
	Each agent application MUST wait to send data until it has		Each agent application MUST wait to send data until it has
	confirmation that the data channel at the peer is instantiated. For		confirmation that the data channel at the peer is instantiated. For
	WebRTC, this is when both data channel stacks have channel parameters		WebRTC, this is when both data channel stacks have channel parameters
	instantiated. This occurs:		instantiated. This occurs:
	o At both peers when a data channel is created without a previously		o At both peers when a data channel is created without a previously
	established SCTP association, as soon as the SCTP association is		established SCTP association, as soon as the SCTP association is
	successfully established.		successfully established.
	skipping to change at page 36, line 18 ¶		skipping to change at page 36, line 18 ¶
	<https://www.rfc-editor.org/info/rfc6525>.		<https://www.rfc-editor.org/info/rfc6525>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	13.2. Informative References		13.2. Informative References
	[I-D.ietf-clue-datachannel]		[I-D.ietf-clue-datachannel]
	Holmberg, C., "CLUE Protocol data channel", draft-ietf-		Holmberg, C., "CLUE Protocol data channel", draft-ietf-
	clue-datachannel-17 (work in progress), April 2019.		clue-datachannel-18 (work in progress), April 2019.
	[I-D.ietf-mmusic-msrp-usage-data-channel]		[I-D.ietf-mmusic-msrp-usage-data-channel]
	Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R.,		Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R.,
	Marcon, J., and J. Recio, "MSRP over Data Channels",		Marcon, J., and J. Recio, "MSRP over Data Channels",
	draft-ietf-mmusic-msrp-usage-data-channel-10 (work in		draft-ietf-mmusic-msrp-usage-data-channel-10 (work in
	progress), April 2019.		progress), April 2019.
	[RFC4582] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor		[RFC4582] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor
	Control Protocol (BFCP)", RFC 4582, DOI 10.17487/RFC4582,		Control Protocol (BFCP)", RFC 4582, DOI 10.17487/RFC4582,
	November 2006, <https://www.rfc-editor.org/info/rfc4582>.		November 2006, <https://www.rfc-editor.org/info/rfc4582>.
	skipping to change at page 36, line 40 ¶		skipping to change at page 36, line 40 ¶
	[RFC4975] Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed.,		[RFC4975] Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed.,
	"The Message Session Relay Protocol (MSRP)", RFC 4975,		"The Message Session Relay Protocol (MSRP)", RFC 4975,
	DOI 10.17487/RFC4975, September 2007,		DOI 10.17487/RFC4975, September 2007,
	<https://www.rfc-editor.org/info/rfc4975>.		<https://www.rfc-editor.org/info/rfc4975>.
	[RFC6455] Fette, I. and A. Melnikov, "The WebSocket Protocol",		[RFC6455] Fette, I. and A. Melnikov, "The WebSocket Protocol",
	RFC 6455, DOI 10.17487/RFC6455, December 2011,		RFC 6455, DOI 10.17487/RFC6455, December 2011,
	<https://www.rfc-editor.org/info/rfc6455>.		<https://www.rfc-editor.org/info/rfc6455>.
	[WebRtcAPI]		[WebRtcAPI]
	Bergkvist, A., Burnett, D., Jennings, C., and A.		Bergkvist, A., Burnett, D., Jennings, C., Narayanan, A.,
	Narayanan, "WebRTC 1.0: Real-time Communication Between		Aboba, B., Brandstetter, T., and J. Bruaroey, "WebRTC 1.0:
	Browsers", World Wide Web Consortium WD-webrtc-20150210,		Real-time Communication Between Browsers", World Wide Web
	February 2015,		Consortium CR CR-webrtc-20180927, September 2018,
	<http://www.w3.org/TR/2015/WD-webrtc-20150210/>.		<https://www.w3.org/TR/2018/CR-webrtc-20180927/>.
	Appendix A. Generic Data Channel Negotiation Aspects When Not Using		Appendix A. Generic Data Channel Negotiation Aspects When Not Using
	DCEP		DCEP
	This appendix summarizes how data channels work in general and		This appendix summarizes how data channels work in general and
	discusses some key aspects, which should be considered for the out-		discusses some key aspects, which should be considered for the out-
	of-band negotiation of data channels if DCEP is not used.		of-band negotiation of data channels if DCEP is not used.
	A WebRTC application creates a data channel by providing a number of		A WebRTC application creates a data channel by providing a number of
	setup parameters (subprotocol, label, maximal number of		setup parameters (subprotocol, label, maximal number of
	skipping to change at page 37, line 42 ¶		skipping to change at page 37, line 42 ¶
	Note: The above SDP media description does not contain any channel-		Note: The above SDP media description does not contain any channel-
	specific information.		specific information.
	A.1. Stream Identifier Numbering		A.1. Stream Identifier Numbering
	Independently from the requested type of negotiation, the application		Independently from the requested type of negotiation, the application
	creating a data channel can either pass the stream identifier to the		creating a data channel can either pass the stream identifier to the
	data channel stack to assign to the data channel or else let the data		data channel stack to assign to the data channel or else let the data
	channel stack pick one identifier from the unused ones.		channel stack pick one identifier from the unused ones.
	To avoid glare situations, each endpoint can moreover own an		To avoid glare situations [RFC3264], each endpoint can moreover own
	exclusive set of stream identifiers, in which case an endpoint can		an exclusive set of stream identifiers, in which case an endpoint can
	only create a data channel with a stream identifier it owns.		only create a data channel with a stream identifier it owns.
	Which set of stream identifiers is owned by which endpoint is		Which set of stream identifiers is owned by which endpoint is
	determined by convention or other means.		determined by convention or other means.
	Note:For data channels negotiated with the DCEP, one endpoint owns		Note:For data channels negotiated with the DCEP, one endpoint owns
	by convention the even stream identifiers, whereas the other owns		by convention the even stream identifiers, whereas the other owns
	the odd stream identifiers, as defined in		the odd stream identifiers, as defined in
	[I-D.ietf-rtcweb-data-protocol].		[I-D.ietf-rtcweb-data-protocol].
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