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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4960 (Obsoleted by RFC 9260) == Outdated reference: A later version (-19) exists of draft-ietf-clue-protocol-02 ** Downref: Normative reference to an Experimental draft: draft-ietf-clue-protocol (ref. 'I-D.ietf-clue-protocol') == Outdated reference: A later version (-15) exists of draft-ietf-clue-signaling-04 ** Downref: Normative reference to an Experimental draft: draft-ietf-clue-signaling (ref. 'I-D.ietf-clue-signaling') == Outdated reference: A later version (-09) exists of draft-ietf-tsvwg-sctp-dtls-encaps-06 == Outdated reference: A later version (-13) exists of draft-ietf-rtcweb-data-channel-12 == Outdated reference: A later version (-09) exists of draft-ietf-rtcweb-data-protocol-08 == Outdated reference: A later version (-07) exists of draft-ietf-tsvwg-sctp-prpolicies-05 Summary: 3 errors (**), 0 flaws (~~), 7 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 CLUE Working Group C. Holmberg 3 Internet-Draft Ericsson 4 Intended status: Standards Track November 21, 2014 5 Expires: May 25, 2015 7 CLUE Protocol Data Channel 8 draft-ietf-clue-datachannel-04 10 Abstract 12 This document defines how to use the WebRTC Data Channel mechanism, 13 together with the Data Channel Establishment Protocol (DCEP) and the 14 SDP-based "SCTP over DTLS" data channel negotiation mechanism, in 15 order to establish a data channel, referred to as CLUE Data Channel, 16 for transporting CLUE protocol messages between two CLUE entities. 18 The document defines the SCTP considerations specific to a CLUE Data 19 Channel, the SDP Media Description- and SDP dcmap attribute values, 20 and the DCEP procedures for opening, a CLUE Data Channel. 22 Details and procedures associated with the CLUE protocol, and the SDP 23 Offer/Answer procedures for negotiating a CLUE data channel, are 24 outside the scope of this document. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on May 25, 2015. 43 Copyright Notice 45 Copyright (c) 2014 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 61 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 3. CLUE Data Channel . . . . . . . . . . . . . . . . . . . . . . 4 63 3.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 3.2. SDP Considerations . . . . . . . . . . . . . . . . . . . 4 65 3.2.1. General . . . . . . . . . . . . . . . . . . . . . . . 4 66 3.2.2. SDP Media Description Fields . . . . . . . . . . . . 4 67 3.2.3. SDP sctpmap Attribute . . . . . . . . . . . . . . . . 5 68 3.2.4. SDP dcpmap Attribute . . . . . . . . . . . . . . . . 5 69 3.2.5. SDP dcsa Attribute . . . . . . . . . . . . . . . . . 5 70 3.2.6. Example . . . . . . . . . . . . . . . . . . . . . . . 6 71 3.3. Data Channel Establishment Protocol (DCEP) Considerations 6 72 3.3.1. General . . . . . . . . . . . . . . . . . . . . . . . 6 73 3.3.2. Open CLUE Data Channel . . . . . . . . . . . . . . . 6 74 3.3.3. Close CLUE Data Channel . . . . . . . . . . . . . . . 6 75 3.3.4. SCTP Association Failure . . . . . . . . . . . . . . 7 76 3.4. SCTP Considerations . . . . . . . . . . . . . . . . . . . 7 77 3.4.1. SCTP Payload Protocol Identifier (PPID) . . . . . . . 7 78 3.4.2. Reliability . . . . . . . . . . . . . . . . . . . . . 7 79 3.4.3. Order . . . . . . . . . . . . . . . . . . . . . . . . 8 80 3.4.4. Stream Reset . . . . . . . . . . . . . . . . . . . . 8 81 3.4.5. SCTP Multihoming . . . . . . . . . . . . . . . . . . 8 82 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 83 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 84 5.1. New WebRTC Data Channel Protocol Value . . . . . . . . . 8 85 5.2. New SDP dcmap attribute subprotocol value . . . . . . . . 9 86 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 87 7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 9 88 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 89 8.1. Normative References . . . . . . . . . . . . . . . . . . 10 90 8.2. Informative References . . . . . . . . . . . . . . . . . 12 91 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12 93 1. Introduction 95 This document defines how to use the WebRTC Data Channel mechanism 96 [I-D.ietf-rtcweb-data-channel], together with the Data Channel 97 Establishment Protocol (DCEP) [I-D.ietf-rtcweb-data-protocol] and the 98 SDP-based "SCTP over DTLS" data channel negotiation mechanism [add- 99 ref], in order to establish a data channel, referred to as CLUE Data 100 Channel, for transporting CLUE protocol [I-D.ietf-clue-protocol] 101 messages between CLUE entities. 103 The document defines the SCTP considerations specific to a CLUE Data 104 Channel, the SDP Media Description- and SDP dcmap attribute values, 105 and the DCEP procedures for opening, a CLUE Data Channel. 107 Details and procedures associated with the CLUE protocol, and the SDP 108 Offer/Answer [RFC3264] procedures for negotiating a CLUE data 109 channel, are outside the scope of this document. 111 2. Conventions 113 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 114 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 115 document are to be interpreted as described in BCP 14, RFC 2119 116 [RFC2119]. 118 WebRTC Data Channel refers to a SCTPoDTLS association 119 [I-D.ietf-tsvwg-sctp-dtls-encaps] that is used to transport non-media 120 data between two entities, according to the procedures in 121 [I-D.ietf-rtcweb-data-channel]. 123 CLUE Data Channel refers to a WebRTC Data Channel 124 [I-D.ietf-rtcweb-data-channel], with a specific set of SCTP 125 characteristics, and usage of the Data Channel Establishment Protocol 126 (DCEP) [I-D.ietf-rtcweb-data-protocol] in order to open a WebRTC Data 127 Channel for the purpose of transporting CLUE protocol 128 [I-D.ietf-clue-protocol] messages between two CLUE entities. 130 CLUE entity refers to a SIP User Agent (UA) [RFC3261] that supports 131 the CLUE Data Channel and the CLUE protocol. 133 CLUE session refers to a SIP session [RFC3261] between to SIP UAs, 134 where a CLUE Data Channel, associated with the SIP session, has been 135 established between the SIP UAs. 137 [RFC4960] defines an SCTP stream as a unidirectional logical channel 138 established from one to another associated SCTP endpoint, within 139 which all user messages are delivered in sequence except for those 140 submitted to the unordered delivery service. 142 [RFC4960] defines an SCTP identifier as a unsigned integer, which 143 identifies a SCTP stream. 145 3. CLUE Data Channel 147 3.1. General 149 This section describes the realization of a CLUE Data Channel. This 150 includes a set of SCTP characteristics specific to a CLUE Data 151 Channel, the usage of the SDP-based "SCTP over DTLS" data channel 152 negotiation mechanism to describe a CLUE data channel in SDP, and the 153 usage of the Data Channel Establishment Protocol (DCEP) 154 [I-D.ietf-rtcweb-data-protocol] in order to open a WebRTC Data 155 Channel for the purpose of transporting CLUE protocol 156 [I-D.ietf-clue-protocol] messages between two CLUE entities. 158 As described in [I-D.ietf-rtcweb-data-channel], the SCTP streams 159 realizing a WebRTC Data Channel must be associated with the same SCTP 160 association. In addition, both SCTP streams realizing the WebRTC 161 Data Channel must use the same SCTP stream identifier value. These 162 rules also apply to a CLUE Data Channel. 164 Within a given CLUE session, a CLUE entity MUST use a single CLUE 165 Data Channel for transport of all CLUE messages towards its peer. 167 3.2. SDP Considerations 169 3.2.1. General 171 This section defines how to construct the SDP Media Description ("m=" 172 line), and the associated SDP dcmap attribute, used to describe a 173 CLUE data channel in SDP. 175 [I-D.ietf-clue-signaling] describes the SDP Offer/Answer procedures 176 for negotiating a CLUE session, including the CLUE controlled media 177 streams and the CLUE data channel. 179 3.2.2. SDP Media Description Fields 181 The field values of the "m=" line for the SCTPoDTLS association are 182 set as following: 184 +---------------+-----------------+-------------+-----------------+ 185 | media | port | proto | fmt | 186 +---------------+-----------------+-------------+-----------------+ 187 | "application" | DTLS port value | "DTLS/SCTP" | SCTP port value | 188 +---------------+-----------------+-------------+-----------------+ 190 Table 1: SDP "proto" field values 192 3.2.3. SDP sctpmap Attribute 194 The field values of the SDP sctpmap attribute, associated with the 195 "m=" line describing the SCTPoDTLS association, are set as following: 197 +----------------------------+----------------------+ 198 | sctpmap-number | app | 199 +----------------------------+----------------------+ 200 | fmt value of the "m=" line | "webrtc-datachannel" | 201 +----------------------------+----------------------+ 203 Table 2: SDP sctpmap attribute values 205 3.2.4. SDP dcpmap Attribute 207 The SDP dcmap attribute [I-D.ejzak-mmusic-data-channel-sdpneg] values 208 for the CLUE data channel, associated with the "m=" line describing 209 the SCTPoDTLS, are set as following: 211 +----------+-------------+----------+---------+----------+----------+ 212 | stream- | subprotocol | label | ordered | max-retr | max-time | 213 | id | | | | | | 214 +----------+-------------+----------+---------+----------+----------+ 215 | Value of | "CLUE" | "CLUE | N/A | N/A | N/A | 216 | the SCTP | | Data | | | | 217 | stream | | Channel" | | | | 218 | used to | | | | | | 219 | realize | | | | | | 220 | the CLUE | | | | | | 221 | data | | | | | | 222 | channel | | | | | | 223 +----------+-------------+----------+---------+----------+----------+ 225 Table 3: SDP dcmap attribute values 227 3.2.5. SDP dcsa Attribute 229 The SDP dcsa attribute [I-D.ejzak-mmusic-data-channel-sdpneg] is not 230 used to describe a CLUE data channel. 232 3.2.6. Example 234 m=application 54111 SCTP/DTLS webrtc-datachannel 235 a=dcmap:2 subprotocol="CLUE";label="CLUE Data Channel" 237 Figure 1: SDP Media Description for a CLUE Data Channel 239 3.3. Data Channel Establishment Protocol (DCEP) Considerations 241 3.3.1. General 243 A CLUE entity MUST support the Data Channel Establishment Protocol 244 (DCEP) [I-D.ietf-rtcweb-data-channel], which can be used in order to 245 open a WebRTC Data Channel. 247 This section describes how to open and close a CLUE data channel 248 using DCEP. 250 3.3.2. Open CLUE Data Channel 252 Once the SCTP association, to be used to realized the CLUE Data 253 Channel, has been established, the offerer [RFC3264] is responsible 254 for opening the CLUE Data Channel. If DCEP is used, the offerer MUST 255 send a DCEP DATA_CHANNEL_OPEN message 256 [I-D.ietf-rtcweb-data-protocol]. The value of the 'protocol' field 257 MUST be "CLUE". The value of the 'channel type' MUST be 258 'DATA_CHANNEL_RELIABLE'. 260 Once the offerer has received the associated DCEP DATA_CHANNEL_ACK 261 message [I-D.ietf-rtcweb-data-protocol], the CLUE Data channel has 262 been opened. 264 If the offerer receives a DCEP DATA_CHANNEL_OPEN message, for the 265 purpose of opening a CLUE Data Channel, the offerer MUST reset the 266 SCTP stream, in order to prevent two CLUE Data Channels from being 267 established within the same CLUE session. The offerer MUST NOT send 268 a DCEP DATA_CHANNEL_ACK message. 270 3.3.3. Close CLUE Data Channel 272 DCEP [I-D.ietf-rtcweb-data-protocol] does not define a message for 273 closing a WebRTC Data Channel. As described in 274 [I-D.ietf-rtcweb-data-protocol], in order to close a CLUE Data 275 Channel, a SCTP reset message is sent, in order to close the SCTP 276 stream associated with the CLUE Data Channel. The SCTP association, 277 and WebRTC Data Channels associated with other SCTP streams, are not 278 affected by the SCTP reset message. 280 3.3.4. SCTP Association Failure 282 In case of SCTP association failure, the offerer is responsible for 283 trying to re-establish the SCTP association (including sending a new 284 SDP offer, if needed). Once the SCTP association has been 285 successfully re-established, the offerer is responsible for sending a 286 DCEP DATA_CHANNEL_OPEN message. 288 3.4. SCTP Considerations 290 3.4.1. SCTP Payload Protocol Identifier (PPID) 292 As described in [I-D.ietf-rtcweb-data-protocol], the PPID value 50 is 293 used when sending a DCEP message on a WebRTC Data Channel. 295 A CLUE entity MUST use the PPID value 51 when sending a CLUE message 296 on a CLUE Data Channel. 298 NOTE: As described in [I-D.ietf-rtcweb-data-channel], the PPID value 299 51 indicates that the SCTP message contains data encoded in a UTF-8 300 format. The PPID value 51 does not indicate what application 301 protocol is transported in a WebRTC Data Channel, only the format in 302 which the data is encoded. 304 +----------+------------+ 305 | Protocol | PPID Value | 306 +----------+------------+ 307 | DCEP | 50 | 308 | CLUE | 51 | 309 +----------+------------+ 311 Table 4: CLUE Data Channel PPID Values 313 3.4.2. Reliability 315 The usage of SCTP for the CLUE Data Channel ensures reliable 316 transport of CLUE protocol [I-D.ietf-clue-protocol] messages. 318 A CLUE entity MUST NOT use the partial reliability and limited 319 retransmission extensions defined in [RFC3758]. 321 NOTE: [I-D.ietf-rtcweb-data-channel] requires the support of the 322 partial reliability extension defined in [RFC3758]. This is not 323 needed for a CLUE Data Channel, as messages are required to always be 324 sent reliably. [I-D.ietf-rtcweb-data-channel] also mandates support 325 of the limited retransmission policy defined in 326 [I-D.ietf-tsvwg-sctp-prpolicies]. 328 3.4.3. Order 330 A CLUE entity MUST use the ordered delivery SCTP service, as 331 described in section 6.6 of [RFC4960]. 333 3.4.4. Stream Reset 335 A CLUE entity MUST support the stream reset extension defined in 336 [RFC6525]. 338 The dynamic address reconfiguration extension defined in [RFC5061] 339 MUST be used to signal the support of the stream reset extension 340 defined in [RFC6525]. Other features of [RFC5061] MUST NOT be used. 342 3.4.5. SCTP Multihoming 344 SCTP multihoming cannot be used for a CLUE Data Channel. 346 NOTE: SCTPoDTLS does not support SCTP multihoming. 348 4. Security Considerations 350 This specification does not introduce new security considerations, in 351 addition to those defined in [I-D.ietf-rtcweb-data-channel] and 352 [I-D.ietf-rtcweb-data-protocol]. Security considerations associated 353 with the CLUE protocol are defined in [I-D.ietf-clue-protocol]. 355 5. IANA Considerations 357 5.1. New WebRTC Data Channel Protocol Value 359 [RFC EDITOR NOTE: Please replace RFC-XXXX with the RFC number of this 360 document.] 362 This document adds the 'CLUE' value to the "WebSocket Subprotocol 363 Name Registry" as follows: 365 Subprotocl Identifier: CLUE 366 Subprotocol Common Name: CLUE 367 Subprotocol Definition: RFC-XXXX 369 5.2. New SDP dcmap attribute subprotocol value 371 [RFC EDITOR NOTE: Please replace RFC-XXXX with the RFC number of this 372 document.] 374 OPEN ISSUE: [I-D.ejzak-mmusic-data-channel-sdpneg] has not yet 375 created a registry for new subprotocol values. 377 6. Acknowledgments 379 Thanks to Paul Kyzivat and Christian Groves for comments on the 380 document. 382 7. Change Log 384 [RFC EDITOR NOTE: Please remove this section when publishing] 386 Changes from draft-ietf-clue-datachannel-03 388 o IANA considerations added. 389 o Editorial changes based on comments from Christian Groves. 391 Changes from draft-ietf-clue-datachannel-02 393 o SDP m- line example fixed. 394 o OPEN ISSUE #1 closed. 395 o - It was agreed (IETF#91) to use draft-ejzak-mmusic-data-channel- 396 sdpneg, as it was adopted as a WG item in MMUSIC. 397 o - Details for draft-ejzak-mmusic-data-channel-sdpneg usage added. 398 o SDP Offer/Answer procedures removed, as they will be defined in 399 the CLUE protocol draft. 400 o References updated. 402 Changes from draft-ietf-clue-datachannel-01 404 o Support of interleaving "MUST"->"SHOULD". 405 o Example updated. 406 o Reference update. 408 Changes from draft-ietf-clue-datachannel-00 410 o SDP Offer/Answer procedures structures according to RFC 3264. 411 o Reference update. 413 Changes from draft-holmberg-clue-datachannel-04 415 o Draft submitted as draft-ietf-clue-data-channel-00. 416 o Editorial nits fixed. 418 o Changes based on comments from Paul Kyzivat (http://www.ietf.org/ 419 mail-archive/web/clue/current/msg03559.html). 420 o - Proto value fixed. 421 o - Explicit text that the partial reliability and limited 422 retransmission policies MUST NOT be used. 423 o - Added open issue on whether the DCEP 'protocol' field value for 424 CLUE should contain a version number. 425 o - Removed paragraph saying that an offerer must not insert more 426 than one m- line describing an SCTPoDTLS association to be used to 427 realize a CLUE Data Channel, as the draft already states that only 428 one CLUE Data Channel per CLUE session shall be opened. 429 o - Added reference to draft-ietf-rtcweb-data-protocol regarding 430 details on reseting SCTP streams. 431 o - Added text saying that the value of the DCEP 'channel type' MUST 432 be DATA_CHANNEL_RELIABLE. 433 o - Clarified that DCEP must be supported, and used in the absence 434 of another mechanism for opening a CLUE Data Channel. 436 Changes from draft-holmberg-clue-datachannel-03 438 o Procedures updated, based on WG agreement (IETF#89) to use DCEP 439 for the CLUE data channel. 440 o Procedures updated, based on WG agreement (IETF#89) that offerer 441 is responsible for sending DCEP DATA_CHANNEL_OPEN. 442 o Editorial changes, and alignments caused by changes in referenced 443 specifications. 445 Changes from draft-holmberg-clue-datachannel-02 447 o PPID value for CLUE messages added 448 o References updated 450 Changes from draft-holmberg-clue-datachannel-01 452 o More text added 454 Changes from draft-holmberg-clue-datachannel-00 456 o Editorial corrections based on comments from Paul K 458 8. References 460 8.1. Normative References 462 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 463 Requirement Levels", BCP 14, RFC 2119, March 1997. 465 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 466 A., Peterson, J., Sparks, R., Handley, M., and E. 467 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 468 June 2002. 470 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model 471 with Session Description Protocol (SDP)", RFC 3264, June 472 2002. 474 [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 475 4960, September 2007. 477 [RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M. 478 Kozuka, "Stream Control Transmission Protocol (SCTP) 479 Dynamic Address Reconfiguration", RFC 5061, September 480 2007. 482 [RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control 483 Transmission Protocol (SCTP) Stream Reconfiguration", RFC 484 6525, February 2012. 486 [I-D.ietf-clue-protocol] 487 Presta, R. and S. Romano, "CLUE protocol", draft-ietf- 488 clue-protocol-02.txt (work in progress), October 2014. 490 [I-D.ietf-clue-signaling] 491 Kyzivat, P., Xiao, L., Groves, C., and S. Romano, "CLUE 492 Signaling", draft-ietf-clue-signaling-04.txt (work in 493 progress), October 2014. 495 [I-D.ietf-tsvwg-sctp-dtls-encaps] 496 Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS 497 Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp- 498 dtls-encaps-06.txt (work in progress), November 2014. 500 [I-D.ietf-rtcweb-data-channel] 501 Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data 502 Channels", draft-ietf-rtcweb-data-channel-12.txt (work in 503 progress), September 2014. 505 [I-D.ietf-rtcweb-data-protocol] 506 Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel 507 Establishment Protocol", draft-ietf-rtcweb-data-protocol- 508 08.txt (work in progress), September 2014. 510 [I-D.ietf-tsvwg-sctp-prpolicies] 511 Tuexen, M., Seggelmann, R., Stewart, R., and S. Loreto, 512 "Additional Policies for the Partial Reliability Extension 513 of the Stream Control Transmission Protocol", draft-ietf- 514 tsvwg-sctp-prpolicies-05.txt (work in progress), November 515 2014. 517 [I-D.ejzak-mmusic-data-channel-sdpneg] 518 Drage, K., Makaraju, R., Ejzak, R., and J. Marcon, "SDP- 519 based WebRTC data channel negotiation", draft-ejzak- 520 mmusic-data-channel-sdpneg-02.txt (work in progress), 521 October 2014. 523 8.2. Informative References 525 [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. 526 Conrad, "Stream Control Transmission Protocol (SCTP) 527 Partial Reliability Extension", RFC 3758, May 2004. 529 Author's Address 531 Christer Holmberg 532 Ericsson 533 Hirsalantie 11 534 Jorvas 02420 535 Finland 537 Email: christer.holmberg@ericsson.com