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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 BFCPbis Working Group G. Camarillo 3 Internet-Draft Ericsson 4 Obsoletes: 4583 (if approved) T. Kristensen 5 Intended status: Standards Track Cisco 6 Expires: May 8, 2014 November 4, 2013 8 Session Description Protocol (SDP) Format for Binary Floor Control 9 Protocol (BFCP) Streams 10 draft-ietf-bfcpbis-rfc4583bis-08 12 Abstract 14 This document specifies how to describe Binary Floor Control Protocol 15 (BFCP) streams in Session Description Protocol (SDP) descriptions. 16 User agents using the offer/answer model to establish BFCP streams 17 use this format in their offers and answers. 19 This document obsoletes RFC 4583. Changes from RFC 4583 are 20 summarized in Section 12. 22 Status of this Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on May 8, 2014. 39 Copyright Notice 41 Copyright (c) 2013 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Fields in the 'm' Line . . . . . . . . . . . . . . . . . . . . 3 59 4. Floor Control Server Determination . . . . . . . . . . . . . . 4 60 5. The 'confid' and 'userid' SDP Attributes . . . . . . . . . . . 6 61 6. Association between Streams and Floors . . . . . . . . . . . . 6 62 7. BFCP Version Negotiation . . . . . . . . . . . . . . . . . . . 7 63 8. BFCP Connection Management . . . . . . . . . . . . . . . . . . 7 64 8.1. TCP Connection Management . . . . . . . . . . . . . . . . 8 65 9. Authentication . . . . . . . . . . . . . . . . . . . . . . . . 8 66 10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 67 11. Security Considerations . . . . . . . . . . . . . . . . . . . 11 68 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 69 12.1. Registration of SDP 'proto' Values . . . . . . . . . . . . 12 70 12.2. Registration of the SDP 'floorctrl' Attribute . . . . . . 12 71 12.3. Registration of the SDP 'confid' Attribute . . . . . . . . 13 72 12.4. Registration of the SDP 'userid' Attribute . . . . . . . . 13 73 12.5. Registration of the SDP 'floorid' Attribute . . . . . . . 13 74 12.6. Registration of the SDP 'bfcpver' Attribute . . . . . . . 14 75 13. Changes from RFC 4583 . . . . . . . . . . . . . . . . . . . . 14 76 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 77 15. Normative References . . . . . . . . . . . . . . . . . . . . . 15 78 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 80 1. Introduction 82 As discussed in the BFCP (Binary Floor Control Protocol) 83 specification [8], a given BFCP client needs a set of data in order 84 to establish a BFCP connection to a floor control server. These data 85 include the transport address of the server, the conference 86 identifier, and the user identifier. 88 One way for clients to obtain this information is to use an offer/ 89 answer [4] exchange. This document specifies how to encode this 90 information in the SDP session descriptions that are part of such an 91 offer/answer exchange. 93 User agents typically use the offer/answer model to establish a 94 number of media streams of different types. Following this model, a 95 BFCP connection is described as any other media stream by using an 96 SDP 'm' line, possibly followed by a number of attributes encoded in 97 'a' lines. 99 2. Terminology 101 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 102 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 103 "OPTIONAL" in this document are to be interpreted as described in BCP 104 14, RFC 2119 [1] and indicate requirement levels for compliant 105 implementations. 107 3. Fields in the 'm' Line 109 This section describes how to generate an 'm' line for a BFCP stream. 111 According to the SDP specification [11], the 'm' line format is the 112 following: 114 m= ... 116 The media field MUST have a value of "application". 118 The port field is set depending on the value of the transport field, 119 as explained below. A port field value of zero has the standard SDP 120 meaning (i.e., rejection of the media stream) regardless of the 121 transport used. 123 When TCP is used as the transport, the port field is set following 124 the rules in [7]. Depending on the value of the 'setup' attribute 125 (discussed in Section 8.1), the port field contains the port to 126 which the remote endpoint will direct BFCP messages or is 127 irrelevant (i.e., the endpoint will initiate the connection 128 towards the remote endpoint) and should be set to a value of 9, 129 which is the discard port. 131 When UDP is used as the transport, the port field contains the 132 port to which the remote endpoint will direct BFCP messages 133 regardless of the value of the 'setup' attribute. 135 We define four new values for the transport field: TCP/BFCP, TCP/TLS/ 136 BFCP, UDP/BFCP, and UDP/TLS/BFCP. TCP/BFCP is used when BFCP runs 137 directly on top of TCP, TCP/TLS/BFCP is used when BFCP runs on top of 138 TLS, which in turn runs on top of TCP. Similarly, UDP/BFCP is used 139 when BFCP runs directly on top of UDP, and UDP/TLS/BFCP is used when 140 BFCP runs on top of DTLS [12], which in turn runs on top of UDP. 142 The fmt (format) list is ignored for BFCP. The fmt list of BFCP 'm' 143 lines SHOULD contain a single "*" character. 145 The following is an example of an 'm' line for a BFCP connection: 147 m=application 50000 TCP/TLS/BFCP * 149 4. Floor Control Server Determination 151 When two endpoints establish a BFCP stream, they need to determine 152 which of them acts as a floor control server. In the most common 153 scenario, a client establishes a BFCP stream with a conference server 154 that acts as the floor control server. Floor control server 155 determination is straight forward because one endpoint can only act 156 as a client and the other can only act as a floor control server. 158 However, there are scenarios where both endpoints could act as a 159 floor control server. For example, in a two-party session that 160 involves an audio stream and a shared whiteboard, the endpoints need 161 to decide which party will be acting as the floor control server. 163 Furthermore, there are situations where both the offerer and the 164 answerer act as both clients and floor control servers in the same 165 session. For example, in a two-party session that involves an audio 166 stream and a shared whiteboard, one party acts as the floor control 167 server for the audio stream and the other acts as the floor control 168 server for the shared whiteboard. 170 We define the 'floorctrl' SDP media-level attribute to perform floor 171 control determination. Its Augmented BNF syntax [2] is: 173 floor-control-attribute = "a=floorctrl:" role *(SP role) 174 role = "c-only" / "s-only" / "c-s" 176 The offerer includes this attribute to state all the roles it would 177 be willing to perform: 179 c-only: The offerer would be willing to act as a floor control 180 client only. 182 s-only: The offerer would be willing to act as a floor control 183 server only. 185 c-s: The offerer would be willing to act both as a floor control 186 client and as a floor control server. 188 If an SDP media description in an offer contains a 'floorctrl' 189 attribute, the answerer accepting that media MUST include one in the 190 corresponding media description of the answer. The answerer includes 191 this attribute to state which role the answerer will perform. That 192 is, the answerer chooses one of the roles the offerer is willing to 193 perform and generates an answer with the corresponding role for the 194 answerer. Table 1 shows the corresponding roles for an answerer, 195 depending on the offerer's role. 197 +---------+----------+ 198 | Offerer | Answerer | 199 +---------+----------+ 200 | c-only | s-only | 201 | s-only | c-only | 202 | c-s | c-s | 203 +---------+----------+ 205 Table 1: Roles 207 The following are the descriptions of the roles when they are chosen 208 by an answerer: 210 c-only: The answerer will act as a floor control client. 211 Consequently, the offerer will act as a floor control server. 213 s-only: The answerer will act as a floor control server. 214 Consequently, the offerer will act as a floor control client. 216 c-s: The answerer will act both as a floor control client and as a 217 floor control server. Consequently, the offerer will also act 218 both as a floor control client and as a floor control server. 220 Endpoints that use the offer/answer model to establish BFCP 221 connections MUST support the 'floorctrl' attribute. A floor control 222 server acting as an offerer or as an answerer SHOULD include this 223 attribute in its session descriptions. 225 If the 'floorctrl' attribute is not used in an offer/answer exchange, 226 by default the offerer and the answerer will act as a floor control 227 client and as a floor control server, respectively. 229 The following is an example of a 'floorctrl' attribute in an offer. 230 When this attribute appears in an answer, it only carries one role: 232 a=floorctrl:c-only s-only c-s 234 5. The 'confid' and 'userid' SDP Attributes 236 We define the 'confid' and the 'userid' SDP media-level attributes. 237 These attributes are used by a floor control server to provide a 238 client with a conference ID and a user ID, respectively. Their 239 Augmented BNF syntax [2] is: 241 confid-attribute = "a=confid:" conference-id 242 conference-id = token 243 userid-attribute = "a=userid:" user-id 244 user-id = token 246 The 'confid' and the 'userid' attributes carry the decimal integer 247 representation of a conference ID and a user ID, respectively. 249 Endpoints that use the offer/answer model to establish BFCP 250 connections MUST support the 'confid' and the 'userid' attributes. A 251 floor control server acting as an offerer or as an answerer SHOULD 252 include these attributes in its session descriptions. 254 6. Association between Streams and Floors 256 We define the 'floorid' SDP media-level attribute. Its Augmented BNF 257 syntax [2] is: 259 floor-id-attribute = "a=floorid:" token [" mstrm:" token *(SP token)] 261 The 'floorid' attribute is used in the SDP media description for BFCP 262 media. It defines a floor identifier and, possibly, associates it 263 with one or more media streams. The token representing the floor ID 264 is the integer representation of the Floor ID to be used in BFCP. 265 The token representing the media stream is a pointer to the media 266 stream, which is identified by an SDP label attribute [9]. 268 Endpoints that use the offer/answer model to establish BFCP 269 connections MUST support the 'floorid' and the 'label' attributes. A 270 floor control server acting as an offerer or as an answerer SHOULD 271 include these attributes in its session descriptions. 273 Note: In [15] 'm-stream' was erroneously used in Section 10. 274 Although the example was non-normative, it is implemented by some 275 vendors and occurs in cases where the endpoint is willing to act as 276 an server. Therefore, it is RECOMMENDED to support parsing and 277 interpreting 'm-stream' the same way as 'mstrm' when receiving. 279 7. BFCP Version Negotiation 281 We define the 'bfcpver' SDP media-level attribute. Its Augmented BNF 282 syntax [2] is: 284 bfcp-version-attribute = "a=bfcpver:" bfcp-version *(SP bfcp-version) 285 bfcp-version = token 287 The 'bfcpver' attribute defines the list of the versions of BFCP 288 supported by the endpoint. Tokens representing versions SHOULD be 289 integers matching the "Version" field that would be presented in the 290 BFCP COMMON-HEADER [8]. The version of BFCP to be used will then be 291 confirmed with a BFCP-level Hello/HelloAck. 293 Endpoints that use the offer/answer model to establish BFCP 294 connections SHOULD support the 'bfcpver' attribute. A floor control 295 server acting as an offerer or as an answerer SHOULD include this 296 attribute in its session descriptions. If a 'bfcpver' attribute is 297 not present, default values are based on the transport specified in 298 the m-line (Section 3). In line with the definition of the Version 299 field in [8], when used over an unreliable transport, an endpoint 300 MUST assume this value to be "2", and when used over a reliable 301 transport, an endpoint MUST assume this value to be "1". 303 8. BFCP Connection Management 305 BFCP connections may use TCP or UDP as the underlying transport. 306 BFCP entities exchanging BFCP messages over UDP will direct the BFCP 307 messages to the peer side connection address and port provided in the 308 SDP 'm' line. TCP connection management is more complicated and is 309 described below. 311 8.1. TCP Connection Management 313 The management of the TCP connection used to transport BFCP is 314 performed using the 'setup' and 'connection' attributes, as defined 315 in [7]. 317 The 'setup' attribute indicates which of the endpoints (client or 318 floor control server) initiates the TCP connection. The 'connection' 319 attribute handles TCP connection reestablishment. 321 The BFCP specification [8] describes a number of situations when the 322 TCP connection between a client and the floor control server needs to 323 be reestablished. However, that specification does not describe the 324 reestablishment process because this process depends on how the 325 connection was established in the first place. BFCP entities using 326 the offer/answer model follow the following rules. 328 When the existing TCP connection is reset following the rules in [8], 329 the client SHOULD generate an offer towards the floor control server 330 in order to reestablish the connection. If a TCP connection cannot 331 deliver a BFCP message and times out, the entity that attempted to 332 send the message (i.e., the one that detected the TCP timeout) SHOULD 333 generate an offer in order to reestablish the TCP connection. 335 Endpoints that use the offer/answer model to establish TCP 336 connections MUST support the 'setup' and 'connection' attributes. 338 9. Authentication 340 When a BFCP connection is established using the offer/answer model, 341 it is assumed that the offerer and the answerer authenticate each 342 other using some mechanism. Once this mutual authentication takes 343 place, all the offerer and the answerer need to ensure is that the 344 entity they are receiving BFCP messages from is the same as the one 345 that generated the previous offer or answer. 347 When SIP is used to perform an offer/answer exchange, the initial 348 mutual authentication takes place at the SIP level. Additionally, 349 SIP uses S/MIME [6] to provide an integrity-protected channel with 350 optional confidentiality for the offer/answer exchange. BFCP takes 351 advantage of this integrity-protected offer/answer exchange to 352 perform authentication. Within the offer/answer exchange, the 353 offerer and answerer exchange the fingerprints of their self-signed 354 certificates. These self-signed certificates are then used to 355 establish the TLS/DTLS connection that will carry BFCP traffic 356 between the offerer and the answerer. 358 BFCP clients and floor control servers follow the rules in [10] 359 regarding certificate choice and presentation. This implies that 360 unless a 'fingerprint' attribute is included in the session 361 description, the certificate provided at the TLS-/DTLS-level MUST 362 either be directly signed by one of the other party's trust anchors 363 or be validated using a certification path that terminates at one of 364 the other party's trust anchors [5]. Endpoints that use the offer/ 365 answer model to establish BFCP connections MUST support the 366 'fingerprint' attribute and SHOULD include it in their session 367 descriptions. 369 When TLS is used with TCP, once the underlying connection is 370 established, the answerer acts as the TLS server regardless of its 371 role (passive or active) in the TCP establishment procedure. 373 Endpoints that use the offer/answer model to establish a DTLS 374 association MUST support the 'setup' attribute, as defined in [7]. 375 When DTLS is used with UDP, the 'setup' attribute indicates which of 376 the endpoints (client or floor control server) initiates the DTLS 377 association setup. The requirements for the offer/answer exchange 378 specified in [13], Section 5 MUST be followed when using DTLS. 380 Informational note: How to determine which endpoint to initiate 381 the TLS/DTLS association depends on the selected underlying 382 transport. It was decided to keep the original semantics in [15] 383 for TCP to retain backwards compatibility. When using UDP, the 384 procedure above was preferred since it adheres to [13] as used for 385 DTLS-SRTP, it does not overload offer/answer semantics, and it 386 works for offerless INVITE in scenarios with B2BUAs. 388 10. Examples 390 For the purpose of brevity, the main portion of the session 391 description is omitted in the examples, which only show 'm' lines and 392 their attributes. 394 The following is an example of an offer sent by a conference server 395 to a client. 397 m=application 50000 TCP/TLS/BFCP * 398 a=setup:passive 399 a=connection:new 400 a=fingerprint:SHA-1 \ 401 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB 402 a=floorctrl:s-only 403 a=confid:4321 404 a=userid:1234 405 a=floorid:1 mstrm:10 406 a=floorid:2 mstrm:11 407 a=bfcpver:1 408 m=audio 50002 RTP/AVP 0 409 a=label:10 410 m=video 50004 RTP/AVP 31 411 a=label:11 413 Note that due to RFC formatting conventions, this document splits SDP 414 across lines whose content would exceed 72 characters. A backslash 415 character marks where this line folding has taken place. This 416 backslash and its trailing CRLF and whitespace would not appear in 417 actual SDP content. 419 The following is the answer returned by the client. 421 m=application 9 TCP/TLS/BFCP * 422 a=setup:active 423 a=connection:new 424 a=fingerprint:SHA-1 \ 425 3D:B4:7B:E3:CC:FC:0D:1B:5D:31:33:9E:48:9B:67:FE:68:40:E8:21 426 a=floorctrl:c-only 427 a=bfcpver:1 428 m=audio 55000 RTP/AVP 0 429 m=video 55002 RTP/AVP 31 431 A similar example using unreliable transport and DTLS is shown below, 432 where the offer is sent from a client. 434 m=application 50000 UDP/TLS/BFCP * 435 a=setup:actpass 436 a=fingerprint:SHA-1 \ 437 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB 438 a=floorctrl:c-only s-only 439 a=confid:4321 440 a=userid:1234 441 a=floorid:1 mstrm:10 442 a=floorid:2 mstrm:11 443 a=bfcpver:2 444 m=audio 50002 RTP/AVP 0 445 a=label:10 446 m=video 50004 RTP/AVP 31 447 a=label:11 449 The following is the answer returned by the server. 451 m=application 55000 UDP/TLS/BFCP * 452 a=setup:active 453 a=fingerprint:SHA-1 \ 454 3D:B4:7B:E3:CC:FC:0D:1B:5D:31:33:9E:48:9B:67:FE:68:40:E8:21 455 a=floorctrl:s-only 456 a=confid:4321 457 a=userid:1234 458 a=floorid:1 mstrm:10 459 a=floorid:2 mstrm:11 460 a=bfcpver:2 461 m=audio 55002 RTP/AVP 0 462 m=video 55004 RTP/AVP 31 464 11. Security Considerations 466 The BFCP [8], SDP [11], and offer/answer [4] specifications discuss 467 security issues related to BFCP, SDP, and offer/answer, respectively. 468 In addition, [7] and [10] discuss security issues related to the 469 establishment of TCP and TLS connections using an offer/answer model. 470 Furthermore, when using DTLS over UDP, considerations for its use 471 with RTP and RTCP are presented in [13]. The requirements for the 472 offer/answer exchange, as listed in Section 5 of that document, MUST 473 be followed. 475 BFCP assumes that an initial integrity-protected channel is used to 476 exchange self-signed certificates between a client and the floor 477 control server. For session descriptions carried in SIP [3], S/MIME 478 [6] is the natural choice to provide such a channel. 480 12. IANA Considerations 482 [Editorial note: The changes in Section 12.1 instruct the IANA to 483 register the two new values UDP/BFCP and UDP/TLS/BFCP for the SDP 484 'proto' field. The new section Section 12.6 registers a new SDP 485 "bfcpver" attribute. The rest is unchanged from [14].] 487 12.1. Registration of SDP 'proto' Values 489 The IANA has registered the following values for the SDP 'proto' 490 field under the Session Description Protocol (SDP) Parameters 491 registry: 493 +--------------+------------+ 494 | Value | Reference | 495 +--------------+------------+ 496 | TCP/BFCP | [RFC XXXX] | 497 | TCP/TLS/BFCP | [RFC XXXX] | 498 | UDP/BFCP | [RFC XXXX] | 499 | UDP/TLS/BFCP | [RFC XXXX] | 500 +--------------+------------+ 502 Table 2: Values for the SDP 'proto' field 504 12.2. Registration of the SDP 'floorctrl' Attribute 506 The IANA has registered the following SDP att-field under the Session 507 Description Protocol (SDP) Parameters registry: 509 Contact name: Gonzalo.Camarillo@ericsson.com 511 Attribute name: floorctrl 513 Long-form attribute name: Floor Control 515 Type of attribute: Media level 517 Subject to charset: No 519 Purpose of attribute: The 'floorctrl' attribute is used to perform 520 floor control server determination. 522 Allowed attribute values: 1*("c-only" / "s-only" / "c-s") 524 12.3. Registration of the SDP 'confid' Attribute 526 The IANA has registered the following SDP att-field under the Session 527 Description Protocol (SDP) Parameters registry: 529 Contact name: Gonzalo.Camarillo@ericsson.com 531 Attribute name: confid 533 Long-form attribute name: Conference Identifier 535 Type of attribute: Media level 537 Subject to charset: No 539 Purpose of attribute: The 'confid' attribute carries the integer 540 representation of a Conference ID. 542 Allowed attribute values: A token 544 12.4. Registration of the SDP 'userid' Attribute 546 The IANA has registered the following SDP att-field under the Session 547 Description Protocol (SDP) Parameters registry: 549 Contact name: Gonzalo.Camarillo@ericsson.com 551 Attribute name: userid 553 Long-form attribute name: User Identifier 555 Type of attribute: Media level 557 Subject to charset: No 559 Purpose of attribute: The 'userid' attribute carries the integer 560 representation of a User ID. 562 Allowed attribute values: A token 564 12.5. Registration of the SDP 'floorid' Attribute 566 The IANA has registered the following SDP att-field under the Session 567 Description Protocol (SDP) Parameters registry: 569 Contact name: Gonzalo.Camarillo@ericsson.com 571 Attribute name: floorid 573 Long-form attribute name: Floor Identifier 575 Type of attribute: Media level 577 Subject to charset: No 579 Purpose of attribute: The 'floorid' attribute associates a floor 580 with one or more media streams. 582 Allowed attribute values: Tokens 584 12.6. Registration of the SDP 'bfcpver' Attribute 586 The IANA has registered the following SDP att-field under the Session 587 Description Protocol (SDP) Parameters registry: 589 Contact name: Gonzalo.Camarillo@ericsson.com 591 Attribute name: bfcpver 593 Long-form attribute name: BFCP Version 595 Type of attribute: Media level 597 Subject to charset: No 599 Purpose of attribute: The 'bfcpver' attribute lists supported BFCP 600 versions. 602 Allowed attribute values: Tokens 604 13. Changes from RFC 4583 606 Following is the list of technical changes and other fixes from [15]. 608 Main purpose of this work was to add signaling support necessary to 609 support BFCP over unreliable transport, as described in [8], 610 resulting in the following changes: 612 Fields in the 'm' Line (Section 3): 613 The section is re-written to remove reference to the 614 exclusivity of TCP as a transport for BFCP streams. The 615 transport field values UDP/BFCP and UDP/TLS/BFCP added. 617 Authentication (Section 9): 618 In last paragraph, made clear that a TCP connection was 619 described. 621 Security Considerations (Section 11): 622 For the DTLS over UDP case, mention existing considerations and 623 requirements for the offer/answer exchange in [13]. 625 Registration of SDP 'proto' Values (Section 12.1): 626 Register the two new values UDP/BFCP and UDP/TLS/BFCP in the 627 SDP parameters registry. 629 The clarification and bug fixes: 631 Errata ID: 712 (Section 4 and Section 6): 632 Language clarification. Don't use terms like an SDP attribute is 633 "used in an 'm' line", instead make clear that the attribute is a 634 media-level attribute. 636 Fix typo in example (Section 10): 637 Do not use 'm-stream' in the SDP example, use the correct 'mstrm' 638 as specified in Section 10. Recommend interpreting 'm-stream' if 639 it is received, since it is present in some implementations. 641 14. Acknowledgements 643 Joerg Ott, Keith Drage, Alan Johnston, Eric Rescorla, Roni Even, and 644 Oscar Novo provided useful ideas for the original [15]. The authors 645 also acknowledge contributions to the revision of BFCP for use over 646 an unreliable transport from Geir Arne Sandbakken, Charles Eckel, 647 Alan Ford, Eoin McLeod and Mark Thompson. 649 15. Normative References 651 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 652 Levels", BCP 14, RFC 2119, March 1997. 654 [2] Crocker, D. and P. Overell, "Augmented BNF for Syntax 655 Specifications: ABNF", STD 68, RFC 5234, January 2008. 657 [3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., 658 Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: 659 Session Initiation Protocol", RFC 3261, June 2002. 661 [4] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with 662 Session Description Protocol (SDP)", RFC 3264, June 2002. 664 [5] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, 665 R., and W. Polk, "Internet X.509 Public Key Infrastructure 666 Certificate and Certificate Revocation List (CRL) Profile", 667 RFC 5280, May 2008. 669 [6] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet Mail 670 Extensions (S/MIME) Version 3.2 Certificate Handling", 671 RFC 5750, January 2010. 673 [7] Yon, D. and G. Camarillo, "TCP-Based Media Transport in the 674 Session Description Protocol (SDP)", RFC 4145, September 2005. 676 [8] Camarillo, G., Drage, K., Kristensen, T., Ott, J., and C. 677 Eckel, "The Binary Floor Control Protocol (BFCP)", 678 draft-ietf-bfcpbis-rfc4582bis-10 (work in progress), 679 November 2013. 681 [9] Levin, O. and G. Camarillo, "The Session Description Protocol 682 (SDP) Label Attribute", RFC 4574, August 2006. 684 [10] Lennox, J., "Connection-Oriented Media Transport over the 685 Transport Layer Security (TLS) Protocol in the Session 686 Description Protocol (SDP)", RFC 4572, July 2006. 688 [11] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 689 Description Protocol", RFC 4566, July 2006. 691 [12] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 692 Security Version 1.2", RFC 6347, January 2012. 694 [13] Fischl, J., Tschofenig, H., and E. Rescorla, "Framework for 695 Establishing a Secure Real-time Transport Protocol (SRTP) 696 Security Context Using Datagram Transport Layer Security 697 (DTLS)", RFC 5763, May 2010. 699 [14] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor Control 700 Protocol (BFCP)", RFC 4582, November 2006. 702 [15] Camarillo, G., "Session Description Protocol (SDP) Format for 703 Binary Floor Control Protocol (BFCP) Streams", RFC 4583, 704 November 2006. 706 Authors' Addresses 708 Gonzalo Camarillo 709 Ericsson 710 Hirsalantie 11 711 Jorvas 02420 712 Finland 714 Email: Gonzalo.Camarillo@ericsson.com 716 Tom Kristensen 717 Cisco 718 Philip Pedersens vei 22 719 N-1366 Lysaker 720 Norway 722 Email: tomkrist@cisco.com, tomkri@ifi.uio.no