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
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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
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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.
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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
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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.
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<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>.
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[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
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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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