--- 1/draft-ietf-mmusic-data-channel-sdpneg-11.txt 2017-03-27 06:13:22.602637353 -0700 +++ 2/draft-ietf-mmusic-data-channel-sdpneg-12.txt 2017-03-27 06:13:22.678639144 -0700 @@ -1,23 +1,23 @@ MMUSIC K. Drage, Ed. Internet-Draft M. Makaraju Intended status: Standards Track Nokia -Expires: July 19, 2017 J. Stoetzer-Bradler +Expires: September 19, 2017 J. Stoetzer-Bradler R. Ejzak J. Marcon Unaffiliated - January 15, 2017 + March 27, 2017 SDP-based Data Channel Negotiation - draft-ietf-mmusic-data-channel-sdpneg-11 + draft-ietf-mmusic-data-channel-sdpneg-12 Abstract The Real-Time Communication in WEB-browsers (RTCWeb) working group is charged to provide protocols to support direct interactive rich communications using audio, video, and data between two peers' web- browsers. For the support of data communication, the RTCWeb working group has in particular defined the concept of bi-directional data channels over SCTP (Stream Control Transmission Protocol), where each data channel might be used to transport other protocols, called @@ -39,21 +39,21 @@ 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 http://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 July 12, 2017. + This Internet-Draft will expire on September 19, 2017. Copyright Notice Copyright (c) 2017 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -84,66 +84,68 @@ 5.1.2. Other Media Level Attributes . . . . . . . . . . . . 10 5.1.2.1. dcsa Attribute . . . . . . . . . . . . . . . . . 10 5.1.2.2. dcsa Multiplexing Category . . . . . . . . . . . 12 5.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . 12 5.2.1. Managing Stream Identifiers . . . . . . . . . . . . . 12 5.2.2. Negotiating Data Channel Parameters . . . . . . . . . 13 5.2.3. Opening a Data Channel . . . . . . . . . . . . . . . 14 5.2.4. Closing a Data Channel . . . . . . . . . . . . . . . 16 5.2.5. Various SDP Offer/Answer Scenarios and Considerations 17 6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 18 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 - 8.1. Subprotocol Identifiers . . . . . . . . . . . . . . . . . 22 - 8.2. New SDP Attributes . . . . . . . . . . . . . . . . . . . 22 - 8.2.1. dcmap . . . . . . . . . . . . . . . . . . . . . . . . 22 - 8.2.2. dcsa . . . . . . . . . . . . . . . . . . . . . . . . 23 - 8.3. New Usage Level . . . . . . . . . . . . . . . . . . . . . 23 - 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24 - 10. CHANGE LOG . . . . . . . . . . . . . . . . . . . . . . . . . 24 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20 + 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 + 8.1. Subprotocol Identifiers . . . . . . . . . . . . . . . . . 21 + 8.2. New SDP Attributes . . . . . . . . . . . . . . . . . . . 21 + 8.2.1. dcmap . . . . . . . . . . . . . . . . . . . . . . . . 21 + 8.2.2. dcsa . . . . . . . . . . . . . . . . . . . . . . . . 22 + 8.3. New Usage Level . . . . . . . . . . . . . . . . . . . . . 22 + 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 + 10. CHANGE LOG . . . . . . . . . . . . . . . . . . . . . . . . . 23 10.1. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-10' . . . . . . . . . . . . . . . . . . . . . . . 24 + sdpneg-11' . . . . . . . . . . . . . . . . . . . . . . . 23 10.2. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-09' . . . . . . . . . . . . . . . . . . . . . . . 24 + sdpneg-10' . . . . . . . . . . . . . . . . . . . . . . . 23 10.3. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-08' . . . . . . . . . . . . . . . . . . . . . . . 25 + sdpneg-09' . . . . . . . . . . . . . . . . . . . . . . . 23 10.4. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-07' . . . . . . . . . . . . . . . . . . . . . . . 25 + sdpneg-08' . . . . . . . . . . . . . . . . . . . . . . . 24 10.5. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-06' . . . . . . . . . . . . . . . . . . . . . . . 26 + sdpneg-07' . . . . . . . . . . . . . . . . . . . . . . . 25 10.6. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-05' . . . . . . . . . . . . . . . . . . . . . . . 26 + sdpneg-06' . . . . . . . . . . . . . . . . . . . . . . . 25 10.7. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-04' . . . . . . . . . . . . . . . . . . . . . . . 27 + sdpneg-05' . . . . . . . . . . . . . . . . . . . . . . . 25 10.8. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-03' . . . . . . . . . . . . . . . . . . . . . . . 27 + sdpneg-04' . . . . . . . . . . . . . . . . . . . . . . . 26 10.9. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 29 + sdpneg-03' . . . . . . . . . . . . . . . . . . . . . . . 27 10.10. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-01' . . . . . . . . . . . . . . . . . . . . . . . 30 + sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 28 10.11. Changes against 'draft-ietf-mmusic-data-channel- - sdpneg-00' . . . . . . . . . . . . . . . . . . . . . . . 32 - 10.12. Changes against 'draft-ejzak-mmusic-data-channel- - sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 35 - 10.13. Changes against '-01' . . . . . . . . . . . . . . . . . 36 - 10.14. Changes against '-00' . . . . . . . . . . . . . . . . . 36 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 - 11.1. Normative References . . . . . . . . . . . . . . . . . . 36 - 11.2. Informative References . . . . . . . . . . . . . . . . . 37 + sdpneg-01' . . . . . . . . . . . . . . . . . . . . . . . 29 + 10.12. Changes against 'draft-ietf-mmusic-data-channel- + sdpneg-00' . . . . . . . . . . . . . . . . . . . . . . . 31 + 10.13. Changes against 'draft-ejzak-mmusic-data-channel- + sdpneg-02' . . . . . . . . . . . . . . . . . . . . . . . 34 + 10.14. Changes against '-01' . . . . . . . . . . . . . . . . . 35 + 10.15. Changes against '-00' . . . . . . . . . . . . . . . . . 35 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 35 + 11.1. Normative References . . . . . . . . . . . . . . . . . . 35 + 11.2. Informative References . . . . . . . . . . . . . . . . . 36 Appendix A. Generic Data Channel Negotiation Aspects When Not - Using DCEP . . . . . . . . . . . . . . . . . . . . . 38 - A.1. Stream Identifier Numbering . . . . . . . . . . . . . . . 39 - A.2. Generic Data Channel Negotiation Not Using DCEP . . . . . 39 - A.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . 39 + Using DCEP . . . . . . . . . . . . . . . . . . . . . 37 + A.1. Stream Identifier Numbering . . . . . . . . . . . . . . . 38 + A.2. Generic Data Channel Negotiation Not Using DCEP . . . . . 38 + A.2.1. Overview . . . . . . . . . . . . . . . . . . . . . . 38 A.2.2. Opening a Data Channel . . . . . . . . . . . . . . . 39 A.2.3. Closing a Data Channel . . . . . . . . . . . . . . . 40 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 1. Introduction The RTCWeb working group has defined the concept of bi-directional data channels running on top of the Stream Control Transmission Protocol (SCTP). RTCWeb allows applications to use data channels. RTCWeb defines an in-band Data Channel Establishment Protocol (DCEP), however other in-band or out-of-band protocols may be used for establishing data channels. Each data channel consists of paired SCTP streams sharing the same SCTP Stream Identifier. Data channels @@ -158,49 +160,49 @@ data channel, and whether it is signaled in-band using DCEP or out- of-band using a non-DCEP protocol (or both). In particular, the SDP offer generated by the RTCweb data channel stack includes no channel- specific information. This document defines SDP offer/answer negotiation procedures to establish data channels for transport of well-defined subprotocols, to enable out-of-band negotiation. These procedures are based on generic SDP offer/answer negotiation rules for SCTP based media transport as specified in [I-D.ietf-mmusic-sctp-sdp] for the SDP "m" - line proto values UDP/DTLS/SCTP and TCP/DTLS/SCTP. In future data - channels could be defined over other SCTP based protocols, such as - SCTP over IP. However, corresponding potential other "m" line proto - values are not considered in this document. + line proto values UDP/DTLS/SCTP and TCP/DTLS/SCTP. In the future, + data channels could be defined over other SCTP based protocols, such + as SCTP over IP. However, corresponding potential other "m" line + proto values are not considered in this document. - This document makes use of MSRP (Message Session Relay Protocol) in - many of the examples. It does not provide a complete specification - of how to negotiate the use of a data channel to transport MSRP. - Procedures specific to each subprotocol such as MSRP are documented - elsewhere. The use of MSRP in some examples is only to show how the - generic procedures described herein might apply to a specific - subprotocol. + This document makes use of MSRP (Message Session Relay Protocol) and + BFCP (Binary Floor Control Protocol) in many of the examples. It + does not provide a complete specification of how to negotiate the use + of a data channel to transport MSRP. Procedures specific to each + subprotocol such as MSRP are documented elsewhere. The use of MSRP + in some examples is only to show how the generic procedures described + herein might apply to a specific subprotocol. 2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Terminology This document uses the following terms: Data channel: A WebRTC data channel as specified in [I-D.ietf-rtcweb-data-channel]. Data channel stack: An entity which, upon application request, runs the data channel protocol to keep track of states, sending - and receive data. If the application is a browser based + and receiving data. If the application is a browser based JavaScript application then this stack resides in the browser. If the application is a native application then this stack resides in the application and is accessible via some sort of APIs. Data channel properties: Fixed properties assigned to a data channel at the time of its creation. Some of these properties determine the way the data channel stack transmits data on this channel (e.g., stream identifier, reliability, order of delivery...). @@ -294,21 +296,21 @@ Syntax: dcmap-value = dcmap-stream-id [ SP dcmap-opt *(";" dcmap-opt) ] dcmap-opt = ordering-opt / subprotocol-opt / label-opt / maxretr-opt / maxtime-opt / priority-opt ; Either only maxretr-opt or maxtime-opt ; is present. - dcmap-stream-id = 1*DIGIT + dcmap-stream-id = 1*5DIGIT ordering-opt = "ordered=" ordering-value ordering-value = "true" / "false" subprotocol-opt = "subprotocol=" quoted-string label-opt = "label=" quoted-string maxretr-opt = "max-retr=" maxretr-value maxretr-value = "0" / integer ; number of retransmissions, ; less than 2^32, ; derived from 'Reliability Parameter' of ; [I-D.ietf-rtcweb-data-protocol] @@ -321,21 +323,21 @@ priority-opt = "priority=" priority-value priority-value = "0" / integer ; unsigned integer value indicating the priority of ; the data channel, ; less than 2^16, ; derived from 'Priority' of ; [I-D.ietf-rtcweb-data-protocol] quoted-string = DQUOTE *(quoted-char / escaped-char) DQUOTE quoted-char = SP / quoted-visible - quoted-visible = %21 / %23-24 / %26-7E ; VCHAR without " or % + quoted-visible = %x21 / %x23-24 / %x26-7E ; VCHAR without " or % escaped-char = "%" HEXDIG HEXDIG DQUOTE = integer = Examples: a=dcmap:0 a=dcmap:1 subprotocol="BFCP";max-time=60000;priority=512 a=dcmap:2 subprotocol="MSRP";ordered=true;label="MSRP" a=dcmap:3 label="Label 1";ordered=false;max-retr=5;priority=128 @@ -480,21 +482,21 @@ Usage Level: media Charset Dependent: no Syntax: dcsa-value = stream-id SP attribute attribute = - Example: + Example (other MSRP related SDP attributes are omitted for brevity): a=dcsa:2 accept-types:text/plain Note that the above reference to [RFC4566] defines where the attribute definition can be found; it does not provide any limitation on support of attributes defined in other documents in accordance with this attribute definition. Note however that not all SDP attributes are suitable as a "a=dcsa:" parameter. [IANA-SDP-Parameters] contains the lists of IANA (Internet Assigned Numbers Authority) registered session and media level or media level @@ -516,22 +518,22 @@ attributes are used in the same way as defined in the original subprotocol specification, also if the subprotocol is transported over a data channel and if the attribute is correspondingly embedded in a "a=dcsa" attribute. There may be cases, where the usage of a subprotocol related media level attribute depends on the subprotocol's transport protocol. In such cases the subprotocol related usage of the attribute is expected to be described for the data channel transport. A data channel specific usage of a subprotocol attribute is expected to be specified - in the same document, which registers the subprotocol's identifier - for data channel usage as described in Section 8.1. + in the same document, that registers the subprotocol's identifier for + data channel usage as described in Section 8.1. 5.1.2.2. dcsa Multiplexing Category The multiplexing category of the "a=dcsa:" attribute is SPECIAL. As the usage of multiple SCTP associations on top of a single DTLS association is outside the scope of [I-D.ietf-mmusic-sctp-sdp], no "a=dcsa:" attribute multiplexing rules are specified for the UDP/DTLS/SCTP and TCP/DTLS/SCTP proto values. If future extensions of [I-D.ietf-mmusic-sctp-sdp] define how to negotiate multiplexing of @@ -576,24 +578,24 @@ 5.2.2. Negotiating Data Channel Parameters Conveying a reliable data channel is achieved by including neither 'max-retr' nor 'max-time' in corresponding SDP offer's or answer's "a=dcmap:" attribute line. Conveying a partially reliable data channel is achieved by including only one of 'max-retr' or 'max- time'. By definition max-retr and max-time are mutually exclusive, so at most one of them MAY be present in the "a=dcmap:" attribute line. If a SDP offer contains both of these parameters then the receiver of such an SDP offer MUST reject the SDP offer. If a SDP - answer contains both of these parameters then the offerer MAY treat - it as an error and MAY assume the associated SDP offer/answer failed - and MAY take appropriate recovery actions. These recovery options - are outside the scope of this document. + answer contains both of these parameters then the offerer MUST treat + the associated SDP offer/answer failed and take appropriate recovery + actions. These recovery options are outside the scope of this + document. The SDP answer SHALL echo the same subprotocol, max-retr, max-time, ordered parameters, if those were present in the offer, and MAY include a label parameter. They MAY appear in any order, which could be different from the SDP offer, in the SDP answer. When sending a subsequent offer or an answer, and for as long as the data channel is still open, the sender MUST replicate the same information. @@ -651,25 +653,23 @@ o Sends the SDP offer. The peer receiving such an SDP offer performs the following: o Parses and applies the SDP offer, taking into account the considerations discussed in Section 5.2.5. o Analyzes the channel parameters and subprotocol attributes to determine whether to accept each offered data channel. - o For accepted data channels, it creates peer instances for the data - channels with the agent using the channel parameters described in - the SDP offer. Note that the agent is asked to create data - channels with SCTP stream identifiers contained in the SDP offer - if the SDP offer is accepted. + o For accepted data channels, the agent MUST create peer instances + for the data channels using the SCTP stream identifiers and + channel parameters contained in the SDP offer. o Generates an SDP answer. o Completes the SDP answer with the "a=dcmap:" and optional "a=dcsa:" attributes needed for each SDP offer/answer negotiated data channel, as described in Section 5.1 and in Section 5.2.2. o Sends the SDP answer. The agent receiving such an SDP answer performs the following: @@ -719,21 +719,21 @@ (unless all data channels are being closed and the SCTP association is no longer needed), since this would close the SCTP association and impact all of the data channels. If the answerer accepts the SDP offer then the answerer MUST close those data channels whose "a=dcmap:" and "a=dcsa:" attribute lines were excluded from the received SDP offer, unless those data channels were already closed, and the answerer MUST also exclude the corresponding attribute lines in the answer. In addition to that, the SDP answerer MAY exclude other data channels which were closed but not yet communicated to the peer. So, the offerer MUST inspect the answer to see if it has to - close other data channels which are now not included in the answer. + close other data channels that are now not included in the answer. If a new SDP offer/answer is used to close data channels then the data channel(s) SHOULD only be closed by the answerer/offerer after a successful SDP answer is sent/received. This delayed closure is RECOMMENDED in order to handle cases where a successful SDP answer is not received, in which case the state of the session SHOULD be kept per the last successful SDP offer/ answer. @@ -758,34 +758,34 @@ 5.2.5. Various SDP Offer/Answer Scenarios and Considerations SDP offer has no "a=dcmap:" attributes. * Initial SDP offer: No data channel is negotiated yet. The DTLS association and SCTP association is negotiated and, if agreed, established as per [I-D.ietf-mmusic-sctp-sdp]. * Subsequent SDP offer: All the SDP offer/answer negotiated data - channels are expected be closed now. The DTLS/SCTP association - remains open for SDP offer/answer or DCEP negotiation of data - channels. + channels are expected to be closed now. The DTLS/SCTP + association remains open for SDP offer/answer or DCEP + negotiation of data channels. SDP answer has no "a=dcmap:" attributes. * Initial SDP answer: 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 offer/answer negotiated data channels that were open at the time of initial offer. The DTLS association and SCTP association will still be setup. * Subsequent SDP answer: All the SDP offer/answer negotiated data - channels are expected be closed now. The SCTP association + channels are expected to be closed now. The SCTP association remains open for future SDP offer/answer or DCEP negotiation of data channels. SDP offer or answer has no "a=dcmap:" attributes but has "a=dcsa:" attributes. * This is considered an error case. In this case the receiver of such an SDP offer or answer SHOULD ignore the "a=dcsa:" attributes and SHOULD process the SDP offer or answer as per above case 'SDP offer has no "a=dcmap:" attributes' or case @@ -810,72 +810,73 @@ entire "a=dcsa" attribute line. SDP offer or answer has an "a=dcsa" attribute, whose subprotocol attribute is known, but whose subprotocol attribute semantic is not known for the data channel transport case. * The receiver of such an SDP offer or answer SHOULD ignore this entire "a=dcsa" attribute line. 6. Examples + SDP offer: m=application 10001 UDP/DTLS/SCTP webrtc-datachannel - c=IN IP4 10.10.10.1 + c=IN IP4 192.0.2.1 a=max-message-size:100000 a=sctp-port:5000 a=setup:actpass a=fingerprint:SHA-1 \ 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB a=dtls-id:4a7565 a=dcmap:0 subprotocol="BFCP";label="BFCP" SDP answer: m=application 10002 UDP/DTLS/SCTP webrtc-datachannel - c=IN IP4 10.10.10.2 + c=IN IP4 192.0.2.2 a=max-message-size:100000 a=sctp-port:5002 a=setup:passive a=fingerprint:SHA-1 \ 5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA a=dtls-id:532d42 Figure 1: Example 1 In the above example the SDP answerer rejected the data channel with stream id 0 either for explicit reasons or because it does not understand the "a=dcmap:" attribute. As a result the offerer will close the data channel created with the SDP offer/answer negotiation option. The SCTP association will still be setup over DTLS. At this point the offerer or the answerer may use DCEP negotiation to open data channels. SDP offer: m=application 10001 UDP/DTLS/SCTP webrtc-datachannel - c=IN IP4 10.10.10.1 + c=IN IP4 192.0.2.1 a=max-message-size:100000 a=sctp-port:5000 a=setup:actpass a=fingerprint:SHA-1 \ 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB a=dtls-id:4a7565 a=dcmap:0 subprotocol="BFCP";label="BFCP" a=dcmap:2 subprotocol="MSRP";label="MSRP" a=dcsa:2 accept-types:message/cpim text/plain a=dcsa:2 path:msrp://alice.example.com:10001/2s93i93idj;dc SDP answer: m=application 10002 UDP/DTLS/SCTP webrtc-datachannel - c=IN IP4 10.10.10.2 + c=IN IP4 192.0.2.2 a=max-message-size:100000 a=sctp-port:5002 a=setup:passive a=fingerprint:SHA-1 \ 5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA a=dtls-id:532d42 a=dcmap:2 subprotocol="MSRP";label="MSRP" a=dcsa:2 accept-types:message/cpim text/plain a=dcsa:2 path:msrp://bob.example.com:10002/si438dsaodes;dc @@ -887,35 +888,35 @@ data channel for BFCP and both offerer and answerer may start using the MSRP data channel (after the SCTP association is set up). The data channel with stream id 0 is free and can be used for future DCEP or SDP offer/answer negotiation. Continuing the example in Figure 2. Subsequent SDP offer: m=application 10001 UDP/DTLS/SCTP webrtc-datachannel - c=IN IP4 10.10.10.1 + c=IN IP4 192.0.2.1 a=max-message-size:100000 a=sctp-port:5000 a=setup:actpass a=fingerprint:SHA-1 \ 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB a=dtls-id:4a7565 a=dcmap:4 subprotocol="MSRP";label="MSRP" a=dcsa:4 accept-types:message/cpim text/plain a=dcsa:4 path:msrp://alice.example.com:10001/2s93i93idj;dc Subsequent SDP answer: m=application 10002 UDP/DTLS/SCTP webrtc-datachannel - c=IN IP4 10.10.10.2 + c=IN IP4 192.0.2.2 a=max-message-size:100000 a=sctp-port:5002 a=setup:passive a=fingerprint:SHA-1 \ 5B:AD:67:B1:3E:82:AC:3B:90:02:B1:DF:12:5D:CA:6B:3F:E5:54:FA a=dtls-id:532d42 a=dcmap:4 subprotocol="MSRP";label="MSRP" a=dcsa:4 accept-types:message/cpim text/plain a=dcsa:4 path:msrp://bob.example.com:10002/si438dsaodes;dc @@ -1008,21 +1009,21 @@ | O/A procedures: | As per Section 5.2 | | Mux category: | SPECIAL. See Section 5.1.2.2 | | Reference: | RFCXXXX | +-----------------------+-------------------------------------------+ 8.3. New Usage Level This document introduces a new "Data Channel Subprotocol Attribute" (dcsa) usage level to the SDP to the IANA SDP att-field registry. SDP attributes that are defined for use at the dcsa usage level only - shall use the dcsa usage level when registering the attribute. If + SHALL use the dcsa usage level when registering the attribute. If existing media attributes are used in a datachannel subprotocol specific way (Section 5.1.2.1), then a new dcsa usage level MUST be defined for the existing media attribute. Where the SDP attribute is applicable to a particular subprotocol/s this SHALL also be registered by indicating the applicable subprotocol identifiers (see Section 8.1) along with the dcsa usage level. E.g. +-----------------------+-------------------------------------------+ | ... | ... | | Usage level: | dcsa(MSRP) | @@ -1033,43 +1034,56 @@ The authors wish to acknowledge the borrowing of ideas from other internet drafts by Salvatore Loreto, Gonzalo Camarillo, Peter Dunkley and Gavin Llewellyn, and to thank Flemming Andreasen, Roni Even, Christian Groves, Gunnar Hellstrom, Christer Holmberg, Paul Kyzivat, Jonathan Lennox, Uwe Rauschenbach and Roman Shpount for their invaluable comments. 10. CHANGE LOG -10.1. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-10' +10.1. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-11' + + o dcmap-stream-id syntax change to limit size to 5 digits. + + o Add missing 'x' prefix to quoted-visible syntax. + + o Align SDP offerer and answerer handling when both max-retr and + max-time are present. + + o Use of TEST-NET-1 ip addresses in examples. + + o Add missing a=dtls-id in one example. + +10.2. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-10' o Removal of the "a=connection" attribute lines from all SDP examples. -10.2. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-09' +10.3. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-09' o In the introduction: * Replacement of the sentence "The RTCWeb working group has defined the concept of bi-directional data channels running on top of SCTP/DTLS (SCTP over the Datagram Transport Layer Security protocol)" with "The RTCWeb working group has defined the concept of bi-directional data channels running on top of the Stream Control Transmission Protocol (SCTP)". * Addition of following sentences to the second paragraph: "These procedures are based on generic SDP offer/answer negotiation rules for SCTP based media transport as specified in [I-D.ietf-mmusic-sctp-sdp] for the SDP "m" line proto values - UDP/DTLS/SCTP and TCP/DTLS/SCTP. In future data channels could - be defined over other SCTP based protocols, such as SCTP over - IP. However, corresponding potential other "m" line proto + UDP/DTLS/SCTP and TCP/DTLS/SCTP. In the future, data channels + could be defined over other SCTP based protocols, such as SCTP + over IP. However, corresponding potential other "m" line proto values are not considered in this document." o Replacement of "DTLS connection" with "DTLS association" throughout the document. o In sections Section 5.1.1.2 and Section 5.1.2.2 removal of the sentences "This document also does not specify multiplexing rules for this attribute for SCTP or SCTP/DTLS proto values". o In the text related to "Subsequent SDP answer" in section @@ -1079,55 +1093,55 @@ o In the text after the second SDP answer in section Section 6 replacement of "... (after SCTP/DTLS association is setup)" with "... (after the SCTP association is set up)". o Addition of [I-D.ietf-mmusic-dtls-sdp] to the list of informative references. o Addition of "a=dtls-id" attribute lines to the SDP offer/answer examples in Section 6. -10.3. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-08' +10.4. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-08' o Addition of definition of "data channel subprotocol" to Section 3 as proposed on the MMUSIC list, https://www.ietf.org/mail- archive/web/mmusic/current/msg15827.html. o Addition of [I-D.ietf-mmusic-rfc4566bis] to list of normative references. o Updates of tables in Section 8.2.1 and Section 8.2.2 as per section 8.2.4 of [I-D.ietf-mmusic-rfc4566bis]. o Addition of new Section 8.3. -10.4. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-07' +10.5. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-07' o Addition of two new paragraphs to Section 5.1.2.1 regarding subprotocol attribute relationship with transport protocol. o Addition of a note to Section 8.1 regarding subprotocols simultaneously defined for data channel and Websocket usage. o Addition of two further SDP offer/answer considerations to Section 5.2.5 regarding unknown subprotocol attributes and known subprotocol attributes with unknown data channel transport related semantic. -10.5. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-06' +10.6. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-06' o Changes addressing Christian Groves's WGLC review comments raised in http://www.ietf.org/mail-archive/web/mmusic/current/ msg15357.html and http://www.ietf.org/mail- archive/web/mmusic/current/msg15359.html. -10.6. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-05' +10.7. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-05' o In IANA registration Section 8.2.1 and Section 8.2.2 replacement of contact name and e-mail address with "MMUSIC Chairs" and "mmusic-chairs@ietf.org". o In Section 5.1.2.1 replacement of "Thus in the example above, the original attribute line "a=accept- types:text/plain" is represented by the attribute line "a=dcsa:2 accept-types:text/ plain", which specifies that this instance of MSRP being transported on the SCTP association using the data channel with @@ -1150,21 +1164,21 @@ o Move of the last but one paragraph of Section 5.1.2.1 starting with "The same syntax applies to ..." right in front of the formal syntax definition of the "dcsa" attribute. o Modifications of the text in Section 5.1.1.2 and Section 5.1.2.2 in order not to explicitly restrict usage of the "a=dcmap:" and "a=dcsa:" attributes to "m" lines with proto values "UDP/DTLS/ SCTP" or "TCP/DTLS/SCTP". -10.7. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-04' +10.8. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-04' o In Section 5.1.1.5 the first (and only) paragraph was "The 'subprotocol' parameter indicates which protocol the client expects to exchange via the channel. 'Subprotocol' is an optional parameter. If the 'subprotocol' parameter is not present, then its value defaults to the empty string." Replacement of this paragraph with following two paragraphs: * The 'subprotocol' parameter indicates which protocol the client expects to exchange via the channel. This parameter maps to @@ -1191,21 +1205,21 @@ o Addition of new Section 5.1.1.2 describing the mux category of the dcmap SDP attribute. This section and the new "a=dcsa:" attribute related mux category section are similar to the "Mux Category" sections of the "a=sctp-port:" and "a=max-message-size:" attributes in [I-D.ietf-mmusic-sctp-sdp]. o Addition of new Section 5.1.2.2 describing the mux category of the dcsa SDP attribute. -10.8. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-03' +10.9. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-03' o In Section 1 replacement of "RTCWeb leaves it open for other applications to use data channels and its in-band DCEP or out-of- band non-DCEP protocols for creating them" with "... to use data channels and its in-band DCEP or other in-band or out-of-band protocols for creating them". Additionally replacement of "In particular, the SDP offer generated by the application includes no channel-specific information" with "... generated by the RTCweb data channel stack includes no channel-specific information". @@ -1249,21 +1263,21 @@ o In Section 5.2.1 replacement of "However, an SDP offer/answer exchange MUST NOT be initiated if the associated SCTP stream is already negotiated via DCEP" with "However, an SCTP stream MUST NOT be referenced in a dcmap or dcsa attribute of an SDP offer/ answer exchange if the associated SCTP stream has already been negotiated via DCEP". o In the examples in Section 6 addition of the previously missing colons to the "a=sctp-port" attribute lines. -10.9. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-02' +10.10. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-02' o Move of reference [I-D.ietf-rtcweb-jsep] from the list of normative references to the list of informative references. o Addition of [IANA-SDP-Parameters] to the list of informative references and addition of following two sentences to the first paragraph after the ABNF definition: "Note however that not all SDP attributes are suitable as "a=dcsa:" parameter. [IANA-SDP-Parameters] contains the lists of IANA registered session and media level or media level only SDP attributes." @@ -1298,21 +1312,21 @@ a=dcmap". o Move of reference [WebRtcAPI] from list of normative references to list of informative references. o Removal of almost all text parts, which discussed JavaScript or other API specific aspects. Such API specific aspects were mainly discussed in sub-sections of Section 5 and Section 5 of draft- ietf-mmusic-data-channel-sdpneg-02. -10.10. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-01' +10.11. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-01' o New Section 4 regarding applicability to SDP offer/answer only. o Addition of new Section 8.1 "Subprotocol identifiers" as subsection of the "IANA Considerations" related Section 8. Also removal of the temporary note "To be completed. As [I-D.ietf- rtcweb-data-protocol] this document should refer to IANA's WebSocket Subprotocol Name Registry defined in [RFC6455]." o In Section 5.2.2: @@ -1348,21 +1362,21 @@ o In Section 5.2.5 the description of bullet point "SDP offer has no a=dcmap attributes - Initial SDP offer:" was "Initial SDP offer: No data channel negotiated yet." Replacement of this description with "Initial SDP offer: No data channel is negotiated yet. The DTLS connection and SCTP association is negotiated and, if agreed, established as per [I-D.ietf-mmusic-sctp-sdp]." o In Section 5.2.5 in both bullet points related to "Subsequent SDP offer" and "Subsequent SDP answer" replacement of "All the externally negotiated data channels must be closed now." with "All - the externally negotiated data channels are expected be closed + the externally negotiated data channels are expected to be closed now.". o In Appendix A.2.2's sixth paragraph beginning with "[ASSUMPTION]" replacement of the two occurrences of "must" with "MUST". o In Section 5.1.1.1 in the definition of the ABNF rule "dcmap-opt" there was a comment saying that "Either only maxretr-opt or maxtime-opt is present. Both MUST not be present." Removal of the second normative sentence and instead addition of following new paragraph to the end of this section: "Within an 'a=dcmap' @@ -1400,21 +1414,21 @@ * In the last but one paragraph replacement of "must" with "The application MUST also close...". o In Section 5.1.2 addition of following note after the formal definition of the 'a=dcsa' attribute: "Note that the above reference to RFC 4566 defines were the attribute definition can be found; it does not provide any limitation on support of attributes defined in other documents in accordance with this attribute definition." -10.11. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-00' +10.12. Changes against 'draft-ietf-mmusic-data-channel-sdpneg-00' o In Section 3 "WebRTC data channel" was defined as "A bidirectional channel consisting of paired SCTP outbound and inbound streams." Replacement of this definition with "Data channel: A WebRTC data channel as specified in [I-D.ietf-rtcweb-data-channel]", and consistent usage of "data channel" in the remainder of the document including the document's headline." o In Section 5 removal of following note: 'OPEN ISSUE: The syntax in [I-D.ietf-mmusic-sctp-sdp] may change as that document progresses. @@ -1530,21 +1544,21 @@ to handle cases where a successful SDP answer is not received, in which case the state of the session SHOULD be kept per the last successful SDP offer/answer." o Although dedicated to "a=dcmap" and "a=dcsa" SDP syntax aspects Section 5.1.1 contained already procedural descriptions related to data channel reliability negotiation. Creation of new Section 5.2.2 and moval of reliability negotiation related text to this new section. -10.12. Changes against 'draft-ejzak-mmusic-data-channel-sdpneg-02' +10.13. Changes against 'draft-ejzak-mmusic-data-channel-sdpneg-02' o Removal of note "[ACTION ITEM]" from section "subprotocol parameter". As [I-D.ietf-rtcweb-data-protocol] this document should refer to IANA's WebSocket Subprotocol Name Registry defined in [RFC6455]. o In whole document, replacement of "unreliable" with "partially reliable", which is used in [I-D.ietf-rtcweb-data-channel] and in [I-D.ietf-rtcweb-data-protocol] in most places. @@ -1580,32 +1594,32 @@ o In the "Examples" section, in the first two SDP offer examples in the a=dcmap attribute lines 'label="BGCP"' was replaced with 'label="BFCP"'. o In all examples, the "m" line proto value "DTLS/SCTP" was replaced with "UDP/DTLS/SCTP" and the "a=fmtp" attribute lines were replaced with "a=max-message-size" attribute lines, as per draft- ietf-mmusic-sctp-sdp-12. -10.13. Changes against '-01' +10.14. Changes against '-01' o Formal syntax for dcmap and dcsa attribute lines. o Making subprotocol as an optional parameter in dcmap. o Specifying disallowed parameter combinations for max-time and max- retr. o Clarifications on WebRTC data channel close procedures. -10.14. Changes against '-00' +10.15. Changes against '-00' o Revisions to identify difference between internal and external negotiation and their usage. o Introduction of more generic terminology, e.g. "application" instead of "browser". o Clarification of how "max-retr and max-time affect the usage of unreliable and reliable WebRTC data channels. @@ -1648,39 +1662,39 @@ [I-D.ietf-rtcweb-data-channel] Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channels", draft-ietf-rtcweb-data-channel-13 (work in progress), January 2015. [I-D.ietf-mmusic-sctp-sdp] Holmberg, C., Shpount, R., Loreto, S., and G. Camarillo, "Session Description Protocol (SDP) Offer/Answer Procedures For Stream Control Transmission Protocol (SCTP) over Datagram Transport Layer Security (DTLS) Transport.", - draft-ietf-mmusic-sctp-sdp-20 (work in progress), December - 2016. + draft-ietf-mmusic-sctp-sdp-25 (work in progress), March + 2017. [I-D.ietf-mmusic-sdp-mux-attributes] Nandakumar, S., "A Framework for SDP Attributes when Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16 (work in progress), December 2016. 11.2. Informative References [I-D.ietf-rtcweb-data-protocol] Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel Establishment Protocol", draft-ietf-rtcweb-data- protocol-09 (work in progress), January 2015. [I-D.ietf-mmusic-dtls-sdp] Holmberg, C. and R. Shpount, "Using the SDP Offer/Answer - Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-15 (work - in progress), October 2016. + Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-22 (work + in progress), March 2017. [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", RFC 4960, DOI 10.17487/RFC4960, September 2007, . [IANA-SDP-Parameters] "Session Description Protocol (SDP) Parameters", Internet Assigned Numbers Authority Protocol Assignments Session Description Protocol (SDP) Parameters,