--- 1/draft-ietf-mmusic-data-channel-sdpneg-26.txt 2019-04-29 02:13:12.124990855 -0700 +++ 2/draft-ietf-mmusic-data-channel-sdpneg-27.txt 2019-04-29 02:13:12.204992887 -0700 @@ -1,24 +1,24 @@ MMUSIC K. Drage Internet-Draft Unaffiliated Intended status: Standards Track M. Makaraju -Expires: October 25, 2019 Nokia +Expires: October 31, 2019 Nokia R. Ejzak J. Marcon Unaffiliated R. Even, Ed. Huawei - April 23, 2019 + April 29, 2019 SDP-based Data Channel Negotiation - draft-ietf-mmusic-data-channel-sdpneg-26 + draft-ietf-mmusic-data-channel-sdpneg-27 Abstract Data channel setup can be done using either the in-band Data Channel Establishment Protocol (DCEP) or using some out-of-band non-DCEP protocol. This document specifies how the SDP (Session Description Protocol) offer/answer exchange can be used to achieve an out-of-band non-DCEP negotiation for establishing a data channel. Status of This Memo @@ -29,21 +29,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. 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." - This Internet-Draft will expire on October 25, 2019. + This Internet-Draft will expire on October 31, 2019. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -229,21 +229,22 @@ as specified in [RFC4960]. Stream identifier: The identifier of the outbound and inbound SCTP streams composing a data channel. 4. Applicability Statement The mechanism in this document only applies to the Session Description Protocol (SDP) [I-D.ietf-mmusic-rfc4566bis] when used 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 This section defines two new SDP media-level attributes that can be used together with the SDP Offer/Answer mechanism to negotiate data channel-specific and subprotocol-specific parameters without the usage of DCEP [I-D.ietf-rtcweb-data-protocol]. The first attribute provides for negotiation of channel-specific parameters. The second attribute provides for negotiation of subprotocol-specific parameters. @@ -620,21 +621,21 @@ ordered=true;max-time= DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED ordered=false;max-time= 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 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 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 When an offerer sends an initial offer, in order to negotiate an SCTP stream for a data channel, the offerer: o SHALL include an SDP dcmap attribute (Section 5 and Section 6.2) associated with the data channel in the "m=" section representing the SCTP association used to realize the data channel; and @@ -663,21 +664,22 @@ An offerer receiving an SDP answer performs the following: o SHALL close any created data channels as described in 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" attribute either the peer does not support "a=dcmap:" attributes or it rejected all the data channels. In either case the offerer closes all the SDP offered data channels that were open at the 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 confirmation that the data channel at the peer is instantiated. For WebRTC, this is when both data channel stacks have channel parameters instantiated. This occurs: o At both peers when a data channel is created without a previously established SCTP association, as soon as the SCTP association is successfully established. @@ -1633,21 +1635,21 @@ . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 13.2. Informative References [I-D.ietf-clue-datachannel] 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] Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R., Marcon, J., and J. Recio, "MSRP over Data Channels", draft-ietf-mmusic-msrp-usage-data-channel-10 (work in progress), April 2019. [RFC4582] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor Control Protocol (BFCP)", RFC 4582, DOI 10.17487/RFC4582, November 2006, . @@ -1655,25 +1657,25 @@ [RFC4975] Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed., "The Message Session Relay Protocol (MSRP)", RFC 4975, DOI 10.17487/RFC4975, September 2007, . [RFC6455] Fette, I. and A. Melnikov, "The WebSocket Protocol", RFC 6455, DOI 10.17487/RFC6455, December 2011, . [WebRtcAPI] - Bergkvist, A., Burnett, D., Jennings, C., and A. - Narayanan, "WebRTC 1.0: Real-time Communication Between - Browsers", World Wide Web Consortium WD-webrtc-20150210, - February 2015, - . + Bergkvist, A., Burnett, D., Jennings, C., Narayanan, A., + Aboba, B., Brandstetter, T., and J. Bruaroey, "WebRTC 1.0: + Real-time Communication Between Browsers", World Wide Web + Consortium CR CR-webrtc-20180927, September 2018, + . Appendix A. Generic Data Channel Negotiation Aspects When Not Using DCEP This appendix summarizes how data channels work in general and discusses some key aspects, which should be considered for the out- of-band negotiation of data channels if DCEP is not used. A WebRTC application creates a data channel by providing a number of setup parameters (subprotocol, label, maximal number of @@ -1705,22 +1707,22 @@ Note: The above SDP media description does not contain any channel- specific information. A.1. Stream Identifier Numbering Independently from the requested type of negotiation, the application 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 channel stack pick one identifier from the unused ones. - To avoid glare situations, each endpoint can moreover own an - exclusive set of stream identifiers, in which case an endpoint can + To avoid glare situations [RFC3264], each endpoint can moreover own + an exclusive set of stream identifiers, in which case an endpoint can only create a data channel with a stream identifier it owns. Which set of stream identifiers is owned by which endpoint is determined by convention or other means. Note:For data channels negotiated with the DCEP, one endpoint owns by convention the even stream identifiers, whereas the other owns the odd stream identifiers, as defined in [I-D.ietf-rtcweb-data-protocol].