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Versions: (draft-nandakumar-rtcweb-sdp) 00 01 02 03 04 05 06 07 08 09 10 11 Draft is active
In: Publication_Requested
Network Working Group                                      S. Nandakumar
Internet-Draft                                               C. Jennings
Intended status: Informational                                     Cisco
Expires: September 27, 2017                               March 26, 2017


                           SDP for the WebRTC
                        draft-ietf-rtcweb-sdp-04

Abstract

   The Web Real-Time Communication [WebRTC] working group is charged to
   provide protocol support for direct interactive rich communication
   using audio, video and data between two peers' web browsers.  With in
   the WebRTC framework, Session Description protocol (SDP) [RFC4566] is
   used for negotiating session capabilities between the peers.  Such a
   negotiation happens based on the SDP Offer/Answer exchange mechanism
   described in [RFC3264].

   This document provides an informational reference in describing the
   role of SDP and the Offer/Answer exchange mechanism for the most
   common WebRTC use-cases.

   This SDP examples provided in this document is still a work in
   progress, but it aims to align closest to the evolving standards
   work.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   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 September 27, 2017.








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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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SDP and the WebRTC  . . . . . . . . . . . . . . . . . . . . .   3
   4.  Offer/Answer and the WebRTC . . . . . . . . . . . . . . . . .   6
   5.  WebRTC Session Description Examples . . . . . . . . . . . . .   6
     5.1.  Some Conventions  . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Basic Examples  . . . . . . . . . . . . . . . . . . . . .   9
       5.2.1.  Audio Only Session  . . . . . . . . . . . . . . . . .   9
       5.2.2.  Audio/Video Session . . . . . . . . . . . . . . . . .  13
       5.2.3.  Data Only Session . . . . . . . . . . . . . . . . . .  18
       5.2.4.  Audio Call On Hold  . . . . . . . . . . . . . . . . .  20
       5.2.5.  Audio with DTMF Session . . . . . . . . . . . . . . .  23
       5.2.6.  One Way Audio/Video Session - Document Camera . . . .  27
       5.2.7.  Audio, Video Session with BUNDLE Support Unknown  . .  30
       5.2.8.  Audio, Video and Data Session . . . . . . . . . . . .  35
       5.2.9.  Audio, Video Session with BUNDLE Unsupported  . . . .  38
       5.2.10. Audio, Video BUNDLED, but Data (Not BUNDLED)  . . . .  43
       5.2.11. Audio Only, Add Video to BUNDLE . . . . . . . . . . .  48
     5.3.  MultiResolution, RTX, FEC Examples  . . . . . . . . . . .  53
       5.3.1.  Sendonly Simulcast Session with 2 cameras and 2
               encodings     per camera  . . . . . . . . . . . . . .  54
       5.3.2.  Successful SVC Video Session  . . . . . . . . . . . .  60
       5.3.3.  Successful Simulcast Video Session with
               Retransmission  . . . . . . . . . . . . . . . . . . .  64
       5.3.4.  Successful 1-way Simulcast Session with 2 resolutions
               and         RTX - One resolution rejected . . . . . .  68
       5.3.5.  Simulcast Video Session with Forward Error Correction  73
     5.4.  Others  . . . . . . . . . . . . . . . . . . . . . . . . .  77
       5.4.1.  Audio Session - Voice Activity Detection  . . . . . .  77
       5.4.2.  Audio Conference - Voice Activity Detection . . . . .  80
       5.4.3.  Successful legacy Interop Fallback with bundle-only .  83



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       5.4.4.  Legacy Interop with RTP/AVP profile . . . . . . . . .  88
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  92
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  92
   8.  Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .  92
   9.  Informative References  . . . . . . . . . . . . . . . . . . .  94
   Appendix A.  Appendix . . . . . . . . . . . . . . . . . . . . . .  99
     A.1.  JSEP SDP Attributes Checklist . . . . . . . . . . . . . .  99
       A.1.1.  Common Checklist  . . . . . . . . . . . . . . . . . .  99
       A.1.2.  RTP Media Description Checklist . . . . . . . . . . . 100
       A.1.3.  DataChannel Media Description checklist . . . . . . . 102
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 102

1.  Introduction

   Javascript Session Exchange Protocol(JSEP) [I-D.ietf-rtcweb-jsep]
   specifies a generic protocol needed to generate [RFC3264] Offers and
   Answers negotiated between the WebRTC peers for setting up, updating
   and tearing down a WebRTC session.  For this purpose, SDP is used to
   construct [RFC3264] Offers/Answers for describing (media and non-
   media) streams as appropriate for the recipients of the session
   description to participate in the session.

   The remainder of this document is organized as follows: Sections 3
   and 4 provides an overview of SDP and the Offer/Answer exchange
   mechanism.  Section 5 provides sample SDP generated for the most
   common WebRTC use-cases.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
   "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
   interpreted as described in [RFC2119].

3.  SDP and the WebRTC

   The purpose of this section is to provide a general overview of SDP
   and its components.  For a more in-depth understanding, the readers
   are advised to refer to [RFC4566].

   The Session Description Protocol (SDP) [RFC4566] describes multimedia
   sessions, which can contain audio, video, whiteboard, fax, modem, and
   other streams.  SDP provides a general purpose, standard
   representation to describe various aspects of multimedia session such
   as media capabilities, transport addresses and related metadata in a
   transport agnostic manner, for the purposes of session announcement,
   session invitation and parameter negotiation.





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   As of today SDP is widely used in the context of Session Initiation
   Protocol [RFC3261], Real-time Transport Protocol [RFC3550] and Real-
   time Streaming Protocol applications [RFC2326].

   Below figure introduces high-level breakup of SDP into components
   that semantically describe a multimedia session, in our case, a
   WebRTC session [WebRTC].  It by no means captures everything about
   SDP and hence, should be used for informational purposes only.

                                                 +---------------------+
                                                 |        v=           |
                                                 +---------------------+
                 +---------------------+         +---------------------+
         ====    |   Session Metadata  |  =====  |        o=           |
         |       +---------------------+         +----------------------
         |                                       +---------------------+
         |                                       |        t=           |
         |                                       +---------------------+
         |
         |
         |                                       +---------------------+
         |                                       |        c=           |
         |                                       +---------------------+
         |       +---------------------+
         ====    | Network Description |   =====
         |       +---------------------+
         |                                       +---------------------+
         |                                       |    a=candidate      |
         |                                       +---------------------+
         |
         |
         |                                       +---------------------+
         |                                       |        m=           |
         |                                       +---------------------+
         |        +---------------------+        +---------------------+
         ====     | Stream Description  |  ===== |      a=rtpmap       |
         |        +---------------------+        +----------------------
         |                                       +---------------------+
         |                                       |      a=fmtp         |
         |                                       +---------------------+
         |                                       +---------------------+
         |                                       |      a=sendrecv..   |
         |                                       +---------------------+
 +---------------+
 |    SEMANTIC   |
 | COMPONENTS OF |
 |     SDP       |
 +---------------+



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         |                                       +---------------------+
         |                                       |      a=crypto       |
         |                                       +---------------------+
         |         +---------------------+       +---------------------+
         ====      |Security Descriptions|  =====|      a=ice-frag     |
         |         +---------------------+       +----------------------
         |                                       +---------------------+
         |                                       |      a=ice-pwd      |
         |                                       +---------------------+
         |                                       +---------------------+
         |                                       |     a=fingerprint   |
         |                                       +---------------------+
         |
         |
         |
         |                                       +---------------------+
         |                                       |      a=rtcp-fb      |
         |                                       +---------------------+
         |         +---------------------+       +---------------------+
         ====      |   Qos,Grouping      |       |                     |
                   |   Descriptions      |  =====|       a=group       |
                   +---------------------+       +----------------------
                                                 +---------------------+
                                                 |       a=rtcpmux     |
                                                 +---------------------+





                   Figure 1: Semantic Components of SDP

   [WebRTC] proposes JavaScript application to fully specify and control
   the signaling plane of a multimedia session as described in the JSEP
   specification [I-D.ietf-rtcweb-jsep].  JSEP provides mechanisms to
   create session characterization and media definition information to
   conduct the session based on SDP exchanges.

   In this context, SDP serves two purposes:

   1.  Provide grammatical structure syntactically.

   2.  Semantically convey participant's intention and capabilities
       required to successfully negotiate a session.







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4.  Offer/Answer and the WebRTC

   This section introduces SDP Offer/Answer Exchange mechanism mandated
   by WebRTC for negotiating session capabilities while setting up,
   updating and tearing down a WebRTC session.  This section is
   intentionally brief in nature and interested readers are recommended
   to refer [RFC3264] for specific details on the protocol operation.

   The Offer/Answer [RFC3264] model specifies rule for the bilateral
   exchange of Session Description Protocol (SDP) messages for creation
   of multimedia streams.  It defines protocol with involved
   participants exchanging desired session characteristics from each
   others perspective constructed as SDP to negotiate the session
   between them.

   In the most basic form,the protocol operation begins by one of the
   participants sending an initial SDP Offer describing its intent to
   start a multimedia communication session.  The participant receiving
   the offer MAY generate an SDP Answer accepting the offer or it MAY
   reject the offer.  If the session is accepted the Offer/Answer model
   guarantees a common view of the multimedia session between the
   participants.

   At any time, either participant MAY generate a new SDP offer that
   updates the session in progress.

   With in the context of WebRTC, the Offer/Answer model defines the
   state-machinery for WebRTC peers to negotiate session descriptions
   between them during the initial setup stages as well as for eventual
   session updates.  Javascript Session Establishment Protocol
   specification [I-D.ietf-rtcweb-jsep] for WebRTC provides the
   mechanism for generating [RFC3264] SDP Offers and Answers in order
   for both sides of the session to agree upon details such as list of
   media formats to be sent/received, bandwidth information, crypto
   parameters, transport parameters, for example.

5.  WebRTC Session Description Examples

   A typical web based real-time multimedia communication session can be
   characterized as below:

   o  It has zero or more Audio only, Video only or Audio/Video RTP
      Sessions,

   o  MAY contain zero or more non-media data sessions,

   o  All the sessions are secured with DTLS-SRTP,




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   o  Supports NAT traversal using ICE mechanism,

   o  Provides RTCP based feedback mechanisms,

   o  Sessions can be over IPv4-only, IPv6-only, dual-stack based
      clients.

5.1.  Some Conventions

   The examples given in this document follow the conventions listed
   below:

   o  In all the examples, Alice and Bob are assumed to be the WebRTC
      peers.

   o  It is assumed that for most of the examples, the support for
      [I-D.ietf-mmusic-sdp-bundle-negotiation] is established apriori
      either out-of-band or as a consequence of successful Offer/Answer
      negotiation between Alice and Bob, unless explicitly stated
      otherwise.

   o  Call-flow diagrams that accompany the use-cases capture only the
      prominent aspects of the system behavior and intentionally is not
      detailed to improve readability.

   o  Eventhough the call-flow diagrams shows SDP being exchanged
      between the parties, it doesn't represent the only way an WebRTC
      setup is expected to work.  Other approaches may involve WebRTC
      applications to exchange the media setup information via non-SDP
      mechanisms as long as they confirm to the [I-D.ietf-rtcweb-jsep]
      API specification.

   o  The SDP examples deviate from actual on-the-wire SDP notation in
      several ways.  This is done to facilitate readability and to
      conform to the restrictions imposed by the RFC formatting rules.

      *  Visual markers/Empty lines in any SDP example are inserted to
         make functional divisions in the SDP clearer, and are not
         actually part of the SDP syntax.

      *  Any SDP line that is indented (compared to the initial line in
         the SDP block) is a continuation of the preceding line.  The
         line break and indent are to be interpreted as a single space
         character.

      *  Excepting the above two conventions, line endings are to be
         interpreted as <CR><LF> pairs (that is, an ASCII 13 followed by
         an ASCII 10).



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   o  Against each SDP line, pointers to the appropriate RFCs are
      provided for further informational reference.  Also an attempt has
      been made to provide explanatory notes to enable better
      understanding of the SDP usage, wherever appropriate.

   o  Following SDP details are common across all the use-cases defined
      in this document unless mentioned otherwise.

      *  DTLS fingerprint for SRTP (a=fingerprint)

      *  RTP/RTCP Multiplexing (a=rtcp-mux)

      *  RTCP Feedback support (a=rtcp-fb)

      *  Host and server-reflexive candidate lines (a=candidate)

      *  SRTP Setup framework parameters (a=setup)

      *  RTCP attribute (a=rtcp)

      *  RTP header extension indicating audio-levels from client to the
         mixer

      For specific details, readers must refer to [I-D.ietf-rtcweb-jsep]
      specification.

   o  The term "Session" is used rather loosely in this document to
      refer to either a "Communication Session" or a "RTP Session" or a
      "RTP Stream" depending on the context.

   o  Payload type 109 is usually used for OPUS, 0 for PCMU, 8 for PCMA,
      99 for H.264 and 120 for VP8 in most of the examples to maintain
      uniformity.

   o  The IP Address:Port combinations '192.168.1.4:61665' (host) and
      '24.23.204.141:54609' (Server Reflexive) is typically used for
      Alice.

   o  The IP Address:Port combinations '192.168.1.7:51556' (host) and
      '98.248.92.77:49203' (Server Reflexive) is typically used for Bob.

   o  In the actual use the values that represent SSRCs, ICE candidate
      foundations, WebRTC Mediastream and MediaStreamTrack Ids shall be
      much larger and/or random than the ones shown in the examples.







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5.2.  Basic Examples

5.2.1.  Audio Only Session

   This common scenario shows SDP for secure two-way audio session with
   Alice offering Opus, PCMU, PCMA and Bob accepting all the offered
   audio codecs.

           2-Way Audio Only Session

   Alice                                Bob
   |                                     |
   |                                     |
   |    Offer(Audio:Opus,PCMU,PCMA)      |
   |------------------------------------>|
   |                                     |
   |                                     |
   |   Answer(Audio:Opus,PCMU,PCMA)      |
   |<------------------------------------|
   |                                     |
   |                                     |
   |Two-way Opus Audio (preferred-codec) |
   |.....................................|
   |                                     |
   |                                     |


   +--------------------------------------------+----------------------+
   | Offer SDP Contents                         | RFC#/Notes           |
   +--------------------------------------------+----------------------+
   | v=0                                        | [RFC4566]            |
   | o=- 20518 0 IN IP4 0.0.0.0                 | [RFC4566] - Session  |
   |                                            | Origin Information   |
   | s=-                                        | [RFC4566]            |
   | t=0 0                                      | [RFC4566]            |
   | a=group:BUNDLE audio                       | [I-D.ietf-mmusic-sdp |
   |                                            | -bundle-negotiation] |
   | a=ice-options:trickle                      | [I-D.ietf-mmusic-tri |
   |                                            | ckle-ice]            |
   | a=identity:eyJpZHAiOnsiZG9tYWluIjoibmlpZi5 | Section 5.6 of [I-D. |
   | odSIsInByb3RvY29sIjoiaWRwLmh0bWwifSwiYXNzZ | ietf-rtcweb-security |
   | XJ0a W9uIjoiZXlKaGJHY2lPaUpTVXpJMU5pSXNJbl | -arch]               |
   | I1Y0NJNklrcFhVeUo5LmV5SmpiMjUwWlc1MGN5STZl |                      |
   | eUptYVc1b lpYSndjbWx1ZENJNlczc2lZV3huYjNKc |                      |
   | GRHaHRJam9pYzJoaExUSTFOaUlzSW1ScFoyVnpkQ0k |                      |
   | 2SWprek9rTXdPa kl6T2pKR09rRXlPakF3T2pBd09q |                      |
   | QkVPalV4T2tGRE9rUXlPalUwT2pZMU9rWTBPak5DT2 |                      |
   | pkRU9qa3lPa1JET2pnN E9qTXpPalV4T2pJek9qUXd |                      |



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   | PamN5T2preE9qZ3pPalZDT2pBeE9qSkdPalV3T2pjN |                      |
   | E9qTkdJbjFkZlN3aWFXUmxib lJwZEhraU9pSnRhWE |                      |
   | 5wUUc1cGFXWXVhSFVpZlEuSTVQdGhKNFFDT05TOFVX |                      |
   | d25OOUh3MEdaTDl3d0RBVGRrTWtFW llmdlNVTTJ6U |                      |
   | md5R09WSGgzRmpnc2FPZklkRnFsNUx6azBFbndVOTN |                      |
   | QOUlCQ0xZOWtia3V1c0V1S25YRGVNLTNIN WFmdTJv |                      |
   | Zl9CTlZjUnB3MmdBdlNBbVR6SlltcEpqMFEtdmV0Tm |                      |
   | tVT1huZE9HLUIzT3ZGb3QwZVNENlZSNUdhb2wyc Gd |                      |
   | uS3FSTktOd3dacEZ1eUZZbFRodHJIdGNiT19WV3o4Q |                      |
   | nZpTThKS25OdExWd1JxNUhMX2ZLTlRCNzFDYkoyWmh |                      |
   | 5W XU1UEdwWDhXcXJMWC1ybm5YSFY3RnhoTTh5OHdr |                      |
   | LWd5cnRZazVnbFlZeUFrcTVqZklSXzRzWER5d19Qc1 |                      |
   | BWTW1aZ XltenVGV3BQTzVFWlJYR0ZpRjFET0o4Q0Q |                      |
   | 3Z3Zta2dUdlBXSWpkemtBIn0=                  |                      |
   | ****** Audio m=line *********              | ******************** |
   |                                            | *********            |
   | m=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8    | [RFC4566]            |
   | c=IN IP4 24.23.204.141                     | [RFC4566]            |
   | a=mid:audio                                | [RFC5888]            |
   | a=msid:ma ta                               | Identifies           |
   |                                            | RTCMediaStream ID    |
   |                                            | (ma) and             |
   |                                            | RTCMediaStreamTrack  |
   |                                            | ID (ta)              |
   | a=sendrecv                                 | [RFC3264] - Alice    |
   |                                            | can send and recv    |
   |                                            | audio                |
   | a=rtpmap:109 opus/48000/2                  | [I-D.ietf-payload-rt |
   |                                            | p-opus] - Opus Codec |
   |                                            | 48khz, 2 channels    |
   | a=rtpmap:0 PCMU/8000                       | [RFC3551] PCMU Audio |
   |                                            | Codec                |
   | a=rtpmap:8 PCMA/8000                       | [RFC3551] PCMA Audio |
   |                                            | Codec                |
   | a=maxptime:120                             | [RFC4566]            |
   | a=ice-ufrag:074c6550                       | [RFC5245] - ICE user |
   |                                            | fragment             |
   | a=ice-                                     | [RFC5245] - ICE      |
   | pwd:a28a397a4c3f31747d1ee3474af08a068      | password             |
   | a=fingerprint:sha-256 19:E2:1C:3B:4B:9F:81 | [RFC5245] - DTLS     |
   | :E6:B8:5C:F4:A5:A8:D8:73:04 :BB:05:2F:70:9 | Fingerprint for SRTP |
   | F:04:A9:0E:05:E9:26:33:E8:70:88:A2         |                      |
   | a=setup:actpass                            | [RFC4145] - Alice    |
   |                                            | can perform DTLS     |
   |                                            | before Answer        |
   |                                            | arrives              |
   | a=dtls-id:1                                | [I-D.ietf-mmusic-dtl |
   |                                            | s-sdp]               |



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   | a=rtcp-mux                                 | [RFC5761] - Alice    |
   |                                            | can perform RTP/RTCP |
   |                                            | Muxing               |
   | a=rtcp:60065 IN IP4 24.23.204.141          | [RFC3605]            |
   | a=rtcp-rsize                               | [RFC5506] - Alice    |
   |                                            | intends to use       |
   |                                            | reduced size RTCP    |
   |                                            | for this session     |
   | a=rtcp-fb:109 nack                         | [RFC5104] -          |
   |                                            | Indicates NACK RTCP  |
   |                                            | feedback support     |
   | a=extmap:1 urn:ietf:params:rtp-hdrext      | [RFC6464] Alice      |
   | :ssrc-audio-level                          | supports RTP header  |
   |                                            | extension to         |
   |                                            | indicate audio       |
   |                                            | levels               |
   | a=extmap:2 urn:ietf:params:rtp-            | [I-D.ietf-mmusic-sdp |
   | hdrext:sdes:mid                            | -bundle-negotiation] |
   | a=candidate:0 1 UDP  2122194687            | [RFC5245] - RTP Host |
   | 192.168.1.4 61665 typ host                 | Candidate            |
   | a=candidate:1 1 UDP  1685987071            | [RFC5245] - RTP      |
   | 24.23.204.141 54609 typ srflx raddr        | Server Reflexive ICE |
   | 192.168.1.4 rport 61665                    | Candidate            |
   | a=candidate:0 2 UDP  2122194687            | [RFC5245] - RTCP     |
   | 192.168.1.4 61667 typ host                 | Host Candidate       |
   | a=candidate:1 2 UDP  1685987071            | [RFC5245] - RTCP     |
   | 24.23.204.141 60065 typ srflx raddr        | Server Reflexive ICE |
   | 192.168.1.4 rport 61667                    | Candidate            |
   | a=end-of-candidates                        | [I-D.ietf-mmusic-tri |
   |                                            | ckle-ice]            |
   +--------------------------------------------+----------------------+

                         Table 1: 5.2.1 SDP Offer


   +-------------------------------------------+-----------------------+
   | Answer SDP Contents                       | RFC#/Notes            |
   +-------------------------------------------+-----------------------+
   | v=0                                       | [RFC4566]             |
   | o=-  16833 0 IN IP4 0.0.0.0               | [RFC4566] - Session   |
   |                                           | Origin Information    |
   | s=-                                       | [RFC4566]             |
   | t=0 0                                     | [RFC4566]             |
   | a=group:BUNDLE audio                      | [I-D.ietf-mmusic-sdp- |
   |                                           | bundle-negotiation]   |
   | a=ice-options:trickle                     | [I-D.ietf-mmusic-tric |
   |                                           | kle-ice]              |
   | a=identity:ew0KICAiaWRwIjp7DQogICAgImRvbW | Section 5.6 of [I-D.i |



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   | FpbiI6ICJjaXNjb3NwYXJrLmNvbSIsDQogICAg In | etf-rtcweb-security-a |
   | Byb3RvY29sIjogImRlZmF1bHQiDQogIH0sDQogICJ | rch]                  |
   | hc3NlcnRpb24iOiAibEp3WkVocmFVOXBTblJo V0U |                       |
   | 1d1VVYzFjR0ZYV1hWaFNGVnBabEV1U1RWUWRHaEtO |                       |
   | RkZEVDA1VE9GVlhkMjVPT1VoM01FZGFURGwz ZDBS |                       |
   | QlZHUnJUV3RGVw0KICAgICAgICAgICAgICBsbG1kb |                       |
   | E5WVFRKNlVtZDVSMDlXU0dnelJtcG5jMkZQ Wmtsa |                       |
   | 1JuRnNOVXg2YXpCRmJuZFZPVE5RT1VsQ1EweFpPV3 |                       |
   | RpYTNWMWMwVjFTMjVZUkdWTkxUTklODQog ICAgIC |                       |
   | AgICAgICAgIFdGbWRUSnZabDlDVGxaalVuQjNNbWR |                       |
   | CZGxOQmJWUjZTbGx0Y0VwcU1GRXRkbVYw VG10VlQ |                       |
   | xaHVaRTlITFVJelQzWkdiM1F3WlZORU5sWlNOVWRo |                       |
   | YjJ3eWMNCiAgICAgICAgICAgICAgR2R1 UzNGU1Rr |                       |
   | dE9kM2RhY0VaMWVVWlpiRlJvZEhKSWRHTmlUMTlXV |                       |
   | jNvNFFuWnBUVGhLUzI1T2RFeFdkMUp4           |                       |
   | TlVoTVgyWkxUbFJDTnpGRFlrb3lXbWg1VyINCn0=  |                       |
   | ****** Audio m=line *********             | ********************* |
   |                                           | ********              |
   | m=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8   | [RFC4566]             |
   | c=IN IP4 98.248.92.77                     | [RFC4566]             |
   | a=mid:audio                               | [RFC5888]             |
   | a=msid:ma ta                              | Identifies            |
   |                                           | RTCMediaStream ID     |
   |                                           | (ma) and              |
   |                                           | RTCMediaStreamTrack   |
   |                                           | ID (ta)               |
   | a=sendrecv                                | [RFC3264] - Bob can   |
   |                                           | send and recv audio   |
   | a=rtpmap:109 opus/48000/2                 | [I-D.ietf-payload-rtp |
   |                                           | -opus] Opus Codec     |
   | a=rtpmap:0 PCMU/8000                      | [RFC3551] PCMU Audio  |
   |                                           | Codec                 |
   | a=rtpmap:8 PCMA/8000                      | [RFC3551] PCMA Audio  |
   |                                           | Codec                 |
   | a=maxptime:120                            | [RFC4566]             |
   | a=ice-ufrag:05067423                      | [RFC5245] - ICE user  |
   |                                           | fragment              |
   | a=ice-                                    | [RFC5245] - ICE       |
   | pwd:1747d1ee3474a28a397a4c3f3af08a068     | password parameter    |
   | a=fingerprint:sha-256 6B:8B:F0:65:5F:78:E | [RFC5245] - DTLS      |
   | 2:51:3B:AC:6F:F3:3F:46:1B:35 :DC:B8:5F:64 | Fingerprint for SRTP  |
   | :1A:24:C2:43:F0:A1:58:D0:A1:2C:19:08      |                       |
   | a=setup:active                            | [RFC4145] - Bob       |
   |                                           | carries out DTLS      |
   |                                           | Handshake in parallel |
   | a=dtls-id:1                               | [I-D.ietf-mmusic-dtls |
   |                                           | -sdp]                 |
   | a=rtcp-mux                                | [RFC5761] - Bob can   |



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   |                                           | perform RTP/RTCP      |
   |                                           | Muxing on port 49203  |
   | a=rtcp-rsize                              | [RFC5506] - Bob       |
   |                                           | intends to use        |
   |                                           | reduced size RTCP for |
   |                                           | this session          |
   | a=rtcp-fb:109 nack                        | [RFC5104] - Indicates |
   |                                           | NACK RTCP feedback    |
   |                                           | support               |
   | a=extmap:1 urn:ietf:params:rtp-hdrext     | [RFC6464] Bob         |
   | :ssrc-audio-level                         | supports audio level  |
   |                                           | RTP header extension  |
   |                                           | as well               |
   | a=extmap:2 urn:ietf:params:rtp-           | [I-D.ietf-mmusic-sdp- |
   | hdrext:sdes:mid                           | bundle-negotiation]   |
   | a=candidate:0 1 UDP 2122194687            | [RFC5245] - RTP/RTCP  |
   | 192.168.1.7 51556 typ host                | Host ICE Candidate    |
   | a=candidate:1 1 UDP 1685987071            | [RFC5245] - RTP/RTCP  |
   | 98.248.92.77 49203 typ srflx raddr        | Server Reflexive ICE  |
   | 192.168.1.7 rport 51556                   | Candidate             |
   | a=end-of-candidates                       | [I-D.ietf-mmusic-tric |
   |                                           | kle-ice]              |
   +-------------------------------------------+-----------------------+

                         Table 2: 5.2.1 SDP Answer


5.2.2.  Audio/Video Session

   Alice and Bob establish a two-way audio and video session with Opus
   as the audio codec and H.264 as the video codec.




















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            2-Way Audio,Video Session

   Alice                                       Bob
   |                                            |
   |                                            |
   |Offer(Audio:Opus,PCMU,PCMA Video:H.264,VP8) |
   |------------------------------------------->|
   |                                            |
   |                                            |
   |      Answer(Audio:Opus,Video:H.264)        |
   |<-------------------------------------------|
   |                                            |
   |                                            |
   |     Two-way Opus Audio, H.264 Video        |
   |............................................|
   |                                            |


   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]Alice wants to lip   |
   |                                   | sync her audio and video      |
   |                                   | sreams                        |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109 0 8                           |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264] - Alice can send    |
   |                                   | and recv audio                |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus] - |
   |                                   | Opus Codec 48khz, 2 channels  |
   | a=rtpmap:0 PCMU/8000              | [RFC3551] PCMU Audio Codec    |
   | a=rtpmap:8 PCMA/8000              | [RFC3551] PCMA Audio Codec    |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245] - ICE user fragment |



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   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245] - ICE password      |
   | 74af08a068                        | parameter                     |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245] - DTLS Fingerprint  |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 | for SRTP                      |
   | :04: BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761] - Alice can perform |
   |                                   | RTP/RTCP Muxing               |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506] - Alice intends to  |
   |                                   | use reduced size RTCP for     |
   |                                   | this session                  |
   | a=rtcp-fb:109 nack                | [RFC5104] - Indicates NACK    |
   |                                   | RTCP feedback support         |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245] - RTP/RTCP Host     |
   | 192.168.1.4 61665 typ host        | Candidate                     |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245] - RTP/RTCP Server   |
   | 24.23.204.141 54609 typ srflx     | Reflexive ICE Candidate       |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 99 120                            |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264] - Alice can send    |
   |                                   | and recv video                |
   | a=rtpmap:99 H264/90000            | [RFC3984] - H.264 Video Codec |
   | a=fmtp:99 profile-level-id=4d0028 | [RFC3984]                     |
   | ;packetization-mode=1             |                               |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8] - VP8  |
   |                                   | video codec                   |
   | a=rtcp-fb:99 nack                 | [RFC5104] - Indicates NACK    |
   |                                   | RTCP feedback support         |
   | a=rtcp-fb:99 nack pli             | [RFC5104] - Indicates support |
   |                                   | for Picture loss Indication   |
   |                                   | and NACK                      |
   | a=rtcp-fb:99 ccm fir              | [RFC5104] - Full Intra Frame  |



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   |                                   | Request-Codec Control Message |
   |                                   | support                       |
   | a=rtcp-fb:120 nack                | [RFC5104] - Indicates NACK    |
   |                                   | RTCP feedback support         |
   | a=rtcp-fb:120 nack pli            | [RFC5104] - Indicates support |
   |                                   | for Picture loss Indication   |
   |                                   | and NACK                      |
   | a=rtcp-fb:120 ccm fir             | [RFC5104] - Full Intra Frame  |
   |                                   | Request-Codec Control Message |
   |                                   | support                       |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                         Table 3: 5.2.2 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]Bob agrees to do the |
   |                                   | same                          |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264] - Bob can send and  |
   |                                   | recv audio                    |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus] - |
   |                                   | Bob accepts only Opus Codec   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245] -  ICE username     |
   |                                   | frag                          |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245] - ICE password      |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245] - DTLS Fingerprint  |



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   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B | for SRTP                      |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145] - Bob carries out   |
   |                                   | DTLS Handshake in parallel    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761] - Bob can perform   |
   |                                   | RTP/RTCP Muxing               |
   | a=rtcp-rsize                      | [RFC5506] - Bob intends to    |
   |                                   | use reduced size RTCP for     |
   |                                   | this session                  |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 3618095783    | [RFC5245] - RTP/RTCP Host ICE |
   | 192.168.1.7 49203 typ host        | Candidate                     |
   | a=candidate:1 1 UDP 565689203     | [RFC5245] - RTP/RTCP Server   |
   | 98.248.92.77 49203 typ srflx      | Reflexive ICE Candidate       |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 99                                |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264] - Bob can send and  |
   |                                   | recv video                    |
   | a=rtpmap:99 H264/90000            | [RFC3984] - Bob accepts H.264 |
   |                                   | Video Codec.                  |
   | a=fmtp:99 profile-level-id=4d0028 | [RFC3984]                     |
   | ;packetization-mode=1             |                               |
   | a=rtcp-fb:99 nack                 | [RFC5104] - Indicates support |
   |                                   | for NACK based RTCP feedback  |
   | a=rtcp-fb:99 nack pli             | [RFC5104] - Indicates support |
   |                                   | for Picture loss Indication   |
   |                                   | and NACK                      |
   | a=rtcp-fb:99 ccm fir              | [RFC5104] - Full Intra Frame  |
   |                                   | Request- Codec Control        |
   |                                   | Message support               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                         Table 4: 5.2.2 SDP Answer



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5.2.3.  Data Only Session

   This scenario illustrates SDP negotiated to setup a data-only session
   based on SCTP Data Channel, thus enabling use-cases such as file-
   transfer for example.


         2-Way DataChannel Session

   Alice                            Bob
   |                                 |
   |                                 |
   |                                 |
   |      Offer(DataChannel)         |
   |-------------------------------->|
   |                                 |
   |                                 |
   |      Answer(DataChannel)        |
   |<--------------------------------|
   |                                 |
   |                                 |
   | Two-way SCTP based DataChannel  |
   |.................................|
   |                                 |
   |                                 |


























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   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE data               | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Application m=line         | ***************************** |
   | *********                         |                               |
   | m=application 54609 UDP/DTLS/SCTP | [I-D.ietf-rtcweb-data-channel |
   | webrtc-datachannel                | ]                             |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:data                        | [RFC5888]                     |
   | a=sendrecv                        | [RFC3264] - Alice can send    |
   |                                   | and recv non-media data       |
   | a=sctp-port:5000                  | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=max-message-size:100000         | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=ice-ufrag:074c6550              | [RFC5245] - Session Level ICE |
   |                                   | parameter                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245] - Session Level ICE |
   | 74af08a068                        | parameter                     |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245] - Session DTLS      |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 | Fingerprint for SRTP          |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP 1694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                         Table 5: 5.2.3 SDP Offer










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   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE data               | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | ****** Application m=line         | ***************************** |
   | *********                         |                               |
   | m=application 49203 UDP/DTLS/SCTP | [I-D.ietf-mmusic-sctp-sdp]    |
   | webrtc-datachannel                |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:data                        | [RFC5888]                     |
   | a=sendrecv                        | [RFC3264] - Bob can send and  |
   |                                   | recv non-media data           |
   | a=sctp-port:5000                  | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=max-message-size:100000         | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=setup:active                    | [RFC4145] - Bob carries out   |
   |                                   | DTLS Handshake in parallel    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=ice-ufrag:c300d85b              | [RFC5245] - Session Level ICE |
   |                                   | username frag                 |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245] - Session Level ICE |
   | efbabd9a2                         | password                      |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245] - Session DTLS      |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B | Fingerprint for SRTP          |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP 1694302207    | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                         Table 6: 5.2.3 SDP Answer


5.2.4.  Audio Call On Hold

   Alice calls Bob, but when Bob answers he places Alice on hold by
   setting the SDP direction attribute to a=inactive in the Answer.





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              Audio On Hold

   Alice                            Bob
   |                                 |
   |                                 |
   |      Offer(Audio:Opus)          |
   |-------------------------------->|
   |                                 |
   |                                 |
   |  Answer(Audio:Opus,a=inactive)  |
   |<--------------------------------|
   |                                 |
   |                                 |
   |      One-way Opus Audio         |
   |.................................|
   |                                 |
   |

   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264] - Alice can send    |
   |                                   | and recv audio                |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus] - |
   |                                   | Opus Codec 48khz, 2 channels  |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245] -  ICE user         |
   |                                   | fragment                      |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245] -  ICE password     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245] - DTLS Fingerprint  |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 | for SRTP                      |



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   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761] - Alice can perform |
   |                                   | RTP/RTCP Muxing               |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104] - Indicates NACK    |
   |                                   | RTCP feedback support         |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                         Table 7: 5.2.4 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=inactive                        | [RFC3264] - Bob puts call On  |
   |                                   | Hold                          |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus] - |
   |                                   | Bob accepts Opus Codec        |



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   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245] - ICE username frag |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245] - ICE password      |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245] - DTLS Fingerprint  |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B | for SRTP                      |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145] - Bob carries out   |
   |                                   | DTLS Handshake in parallel    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761] - Bob can perform   |
   |                                   | RTP/RTCP Muxing               |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245] - Host candidate    |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245] -  Server Reflexive |
   | 24.23.204.141 49203 typ srflx     | candidate                     |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                         Table 8: 5.2.4 SDP Answer


5.2.5.  Audio with DTMF Session

   In this example, Alice wishes to establish two separate audio
   streams, one for normal audio and the other for telephone-events.
   Alice offers first audio stream with three codecs and the other with
   [RFC2833] tones (for DTMF).  Bob accepts both the audio streams by
   choosing Opus as the audio codec and telephone-event for the other
   stream.














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               Audio Session with DTMF

   Alice                                              Bob
   |                                                   |
   |                                                   |
   |                                                   |
   |  Offer(Audio:Opus,PCMU,PCMA Audio:telephone-event)|
   |-------------------------------------------------->|
   |                                                   |
   |                                                   |
   |    Answer(Audio:Opus, Audio:telephone-event)      |
   |<--------------------------------------------------|
   |                                                   |
   |                                                   |
   |   Opus audio stream and telephone-event stream    |
   |...................................................|
   |                                                   |

   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio dtmf         | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109 0 8                           |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264] - Alice can send    |
   |                                   | and recv audio                |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus] - |
   |                                   | Opus Codec 48khz, 2 channels  |
   | a=rtpmap:0 PCMU/8000              | [RFC3551] PCMU Audio Codec    |
   | a=rtpmap:8 PCMA/8000              | [RFC3551] PCMA Audio Codec    |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245] -  ICE user         |
   |                                   | fragment                      |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245] - ICE password      |
   | 74af08a068                        | parameter                     |



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   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245] - DTLS Fingerprint  |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 | for SRTP                      |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761] - Alice can perform |
   |                                   | RTP/RTCP Muxing               |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104] - Indicates NACK    |
   |                                   | RTCP feedback support         |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** DTMF m=line *********      | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 126                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:dtmf                        | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendonly                        | [RFC3264] - Alice can send    |
   |                                   | DTMF Events                   |
   | a=rtpmap:126 telephone-event/8000 | [RFC2833]                     |
   | a=rtcp-fb:109 nack                | [RFC5104] - Indicates NACK    |
   |                                   | RTCP feedback support         |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                         Table 9: 5.2.5 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |



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   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio dtmf         | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264] - Bob can send and  |
   |                                   | receive Opus audio            |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus] - |
   |                                   | Bob accepts Opus Codec        |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245] -  ICE username     |
   |                                   | frag                          |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245] -  ICE password     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245] -  Fingerprint for  |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B | SRTP                          |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145] - Bob carries out   |
   |                                   | DTLS Handshake in parallel    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761] - Bob can perform   |
   |                                   | RTP/RTCP Muxing on port 49203 |
   | a=rtcp-rsize                      | [RFC5506] - Alice intends to  |
   |                                   | use reduced size RTCP for     |
   |                                   | this session                  |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2122194687    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP 1685987071    | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** DTMF m=line *********      | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 126                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |



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   | a=mid:dtmf                        | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=recvonly                        | [RFC3264] - Alice can receive |
   |                                   | DTMF events                   |
   | a=rtpmap:126 telephone-event/8000 | [RFC2833]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                        Table 10: 5.2.5 SDP Answer


5.2.6.  One Way Audio/Video Session - Document Camera

   In this scenario Alice and Bob engage in a 1 way audio and video
   session with Bob receiving Alice's audio and her presentation slides
   as video stream.



      One Way Audio & Video Session - Document Camera


   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |                                                      |
   |   Alice Offers sendonly audio and video streams.     |
   |  The video stream corresponds to her presentation    |
   |                                                      |
   |           Offer(Audio:Opus, Video: VP8)              |
   |----------------------------------------------------->|
   |                                                      |
   |                                                      |
   |            (Audio:Opus, Video: VP8)                  |
   |<-----------------------------------------------------|
   |                                                      |
   |                                                      |
   |          One-way Opus Audio, VP8 Video               |
   |......................................................|
   |   Bob can hear Alice and see her presentation slides.|
   |                                                      |
   |                                                      |


   +-----------------------------------+-------------------------------+



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   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendonly                        | [RFC3264] - Send only audio   |
   |                                   | stream                        |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245]                     |
   | 24.23.204.141 54609 typ host      |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |



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   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendonly                        | [RFC3264] - Send only video   |
   |                                   | stream                        |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=content:slides                  | [RFC4796] -Alice's            |
   |                                   | presentation video stream     |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                         Table 11: 5.2.6 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 16833 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=recvonly                        | [RFC3264] - Receive only      |
   |                                   | audio stream                  |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |



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   | a=setup:active                    | [RFC4145] - Bob carries out   |
   |                                   | DTLS Handshake in parallel    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 98.248.92.77 49203 typ host       |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=content:slides                  | [RFC4796]presentation stream  |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                        Table 12: 5.2.6 SDP Answer


5.2.7.  Audio, Video Session with BUNDLE Support Unknown

   In this example, since Alice is unsure of the Bob's support of the
   BUNDLE framework, following steps are performed in order to negotiate
   and setup a BUNDLE Address for the session

   o  An SDP Offer, in which the Alice assigns unique addresses to each
      "m=" line in the BUNDLE group, and requests the Answerer to select
      the Offerer's BUNDLE address.

   o  An SDP Answer, in which the Bob indicates its support for BUNDLE,
      selects the offerer's BUNDLE address, selects its own BUNDLE
      address and associates it with each BUNDLED m=line within the
      BUNDLE group.



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   Once the Offer/Answer exchange completes, both Alice and Bob each end
   up using single RTP Session for both the Media Streams.



    Two-Way Secure Audio,Video with BUNDLE support unknown

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |   Alice offers BUNDLE support with unique address    |
   |        for the audio and video m-line                |
   |                                                      |
   |                                                      |
   |          Offer(Audio:Opus Video:VP8)                 |
   |----------------------------------------------------->|
   |                                                      |Bob
   |                                                      |supports
   |                                                      |BUNDLE,
   |                                                      |Uses
   |                                                      |identical
   |                                                      |address
   |          Answer(Audio:Opus Video:VP8)                |
   |<-----------------------------------------------------|
   |                                                      |
   |    2 Way Call with Audio and Video Multiplexed       |
   |......................................................|
   |                                                      |


   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice supports    |
   |                                   | grouping of m=lines under     |
   |                                   | BUNDLE semantics              |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888] Audio m=line part   |



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   |                                   | of BUNDLE group with a unique |
   |                                   | port number                   |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54610 IN IP4 24.23.204.141 | [RFC3605] - RTCP port         |
   |                                   | different from RTP Port       |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245] - RTP host          |
   | 192.168.1.4 61665 typ host        | candidate                     |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245] - RTP Server        |
   | 24.23.204.141 54609 typ srflx     | Reflexive candidate           |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=candidate:0 2 UDP 2122194687    | [RFC5245] - RTCP host         |
   | 192.168.1.4 61666 typ host        | candidate                     |
   | a=candidate:1 2 UDP  1685987071   | [RFC5245] - RTCP Server       |
   | 24.23.204.141 54610 typ srflx     | Reflexive candidate           |
   | raddr 192.168.1.4 rport 61666     |                               |
   | ****** Video m=line *********     | ***************************** |
   | m=video 62537 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:video                       | [RFC5888] Video m=line part   |
   |                                   | of the Bundle group with a    |
   |                                   | unique port number            |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |



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   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=ice-ufrag:6550074c              | [RFC5245]                     |
   | a=ice-pwd:74af08a068a28a397a4c3f3 | [RFC5245]                     |
   | 1747d1ee34                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:2                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:62538 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245] - RTP Host          |
   | 192.168.1.4 61886 typ host        | candidate                     |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245] - RTP Server        |
   | 24.23.204.141 62537 typ srflx     | Reflexive candidate           |
   | raddr 192.168.1.4 rport 61886     |                               |
   | a=candidate:0 2 2122194687        | [RFC5245] - RTCP host         |
   | 192.168.1.4 61888 typ host        | candidate                     |
   | a=candidate:1 2 UDP 1685987071    | [RFC5245] - RTCP Server       |
   | 24.23.204.141 62538 typ srflx     | Reflexive candidate           |
   | raddr 192.168.1.4 rport 61888     |                               |
   +-----------------------------------+-------------------------------+

                    Table 13: 5.2.7 SDP Offer w/BUNDLE


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Bob supports      |
   |                                   | BUNDLE semantics.             |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |



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   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888] Audio m=line part   |
   |                                   | of the BUNDLE group           |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145] - Bob carries out   |
   |                                   | DTLS Handshake in parallel    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2122194687    | [RFC5245]                     |
   | 192.168.1.7 49203 typ host        |                               |
   | a=candidate:1 1 UDP 1685987071    | [RFC5245]                     |
   | 98.248.92.77 51556 typ srflx      |                               |
   | raddr 192.168.1.7 rport 49203     |                               |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:video                       | [RFC5888] Video m=line part   |
   |                                   | of the BUNDLE group with the  |
   |                                   | port from audio line repeated |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |



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   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                    Table 14: 5.2.7 SDP Answer w/BUNDLE


5.2.8.  Audio, Video and Data Session

   This example shows SDP for negotiating a session with Audio, Video
   and data streams between Alice and Bob with BUNDLE support known.



       Audio,Video,Data with BUNDLE support known

   Alice                                       Bob
   |                                            |
   |                                            |
   |   Alice indicates BUNDLE support with      |
   |  identical address across all the m=lines  |
   |                                            |
   |                                            |
   |     Offer(Audio:Opus Video:VP8 Data)       |
   |------------------------------------------->|
   |                                            |Bob does
   |                                            |the same
   |    Answer(Audio:Opus,Video:VP8 Data)       |
   |<-------------------------------------------|
   |                                            |
   |                                            |
   |                                            |
   |    Two-way Audio,Video, Data multiplexed   |
   |............................................|
   |                                            |
   |                                            |


   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video data   | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |



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   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=mid:audio                       | [RFC5888]                     |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |



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   | hdrext:sdes:mid                   | egotiation]                   |
   | ****** Application m=line         | ***************************** |
   | *********                         |                               |
   | m=application 54609 UDP/DTLS/SCTP | [I-D.ietf-rtcweb-data-channel |
   | webrtc-datachannel                | ]                             |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:data                        | [RFC5888]                     |
   | a=sctp-port:5000                  | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=max-message-size:100000         | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=sendrecv                        | [RFC3264]                     |
   +-----------------------------------+-------------------------------+

                         Table 15: 5.2.8 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 16833 0 IN IP4 0.0.0.0        | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video data   | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=mid:audio                       | [RFC5888]                     |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |



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   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2122194687    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP 1685987071    | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | ****** Application m=line         | ***************************** |
   | *********                         |                               |
   | m=application 49203 UDP/DTLS/SCTP | [I-D.ietf-mmusic-sctp-sdp]    |
   | webrtc-datachannel                |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:data                        | [RFC5888]                     |
   | a=sctp-port:5000                  | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=max-message-size:100000         | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=sendrecv                        | [RFC3264]                     |
   +-----------------------------------+-------------------------------+

                        Table 16: 5.2.8 SDP Answer


5.2.9.  Audio, Video Session with BUNDLE Unsupported

   This use-case illustrates SDP Offer/Answer exchange where the far-end
   (Bob) either doesn't support media bundling or doesn't want to group
   m=lines over a single 5-tuple.





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   The same is indicated by dropping the "a=group:BUNDLE" line and
   BUNDLE RTP header extension in the Answer SDP.

   On successful Offer/Answer exchange, Alice and Bob each end up using
   unique 5-tuple for audio and video media streams respectively.



      Two-Way Secure Audio,Video with BUNDLE Unsupported

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |     Alice offers BUNDLE support with unique address  |
   |           for the audio and video m-line             |
   |                                                      |
   |                                                      |
   |           Offer(Audio:Opus Video:VP8)                |
   |----------------------------------------------------->|
   |                                                      |Bob
   |                                                      |doesn't
   |                                                      |support
   |                                                      |BUNDLE
   |           Answer(Audio:Opus Video:VP8)               |
   |<-----------------------------------------------------|
   |                                                      |Bob uses
   |                                                      |unique
   |                                                      |addresses
   |                                                      |across the
   |                                                      |m=lines
   |                                                      |
   |2Way Call with Audio and Video on different 5-tuples  |
   |......................................................|
   |                                                      |
   |                                                      |


   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice supports    |
   |                                   | grouping of m=lines under     |
   |                                   | BUNDLE semantics              |



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   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888] Audio m=line part   |
   |                                   | of BUNDLE group with a unique |
   |                                   | port number                   |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:55232 IN IP4 24.23.204.141 | [RFC3605] - RTCP port         |
   |                                   | different from RTP port       |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=candidate:0 2 UDP 2122194687    | [RFC5245]                     |
   | 192.168.1.4 61666 typ host        |                               |
   | a=candidate:1 2 UDP  1685987071   | [RFC5245]                     |
   | 24.23.204.141 55232 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61666     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 54332 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |



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   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:video                       | [RFC5888] Video m=line part   |
   |                                   | of the BUNDLE group with a    |
   |                                   | unique port number            |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=ice-ufrag:7872093               | [RFC5245]                     |
   | a=ice-pwd:ee3474af08a068a28a397a4 | [RFC5245]                     |
   | c3f31747d1                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145] - Alice can perform |
   |                                   | DTLS before Answer arrives    |
   | a=dtls-id:2                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:60052 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2122194687   | [RFC5245]                     |
   | 192.168.1.4 71775 typ host        |                               |
   | a=candidate:1 1 UDP  1685987071   | [RFC5245]                     |
   | 24.23.204.141 54332 typ srflx     |                               |
   | raddr 192.168.1.4 rport 71775     |                               |
   | a=candidate:0 2 2122194687        | [RFC5245]                     |
   | 192.168.1.4 71776 typ host        |                               |
   | a=candidate:1 2 UDP 1685987071    | [RFC5245]                     |
   | 24.23.204.141 60052 typ srflx     |                               |
   | raddr 192.168.1.4 rport 71776     |                               |
   +-----------------------------------+-------------------------------+

                    Table 17: 5.2.9 SDP Offer w/BUNDLE


   +----------------------------------------+--------------------------+
   | Answer SDP Contents                    | RFC#/Notes               |
   +----------------------------------------+--------------------------+
   | v=0                                    | [RFC4566]                |
   | o=-  16833 0 IN IP4 0.0.0.0            | [RFC4566]                |
   | s=-                                    | [RFC4566]                |



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   | t=0 0                                  | [RFC4566]                |
   | a=group:LS audio video                 | [RFC5888]                |
   | a=ice-options:trickle                  | [I-D.ietf-mmusic-trickle |
   |                                        | -ice]                    |
   | ****** Audio m=line *********          | ************************ |
   |                                        | *****                    |
   | m=audio 53214 UDP/TLS/RTP/SAVPF 109    | [RFC4566]                |
   | c=IN IP4 98.248.92.77                  | [RFC4566]                |
   | a=mid:audio                            | [RFC5888]                |
   | a=msid:ma ta                           | Identifies               |
   |                                        | RTCMediaStream ID (ma)   |
   |                                        | and RTCMediaStreamTrack  |
   |                                        | ID (ta)                  |
   | a=sendrecv                             | [RFC3264]                |
   | a=rtpmap:109 opus/48000/2              | [I-D.ietf-payload-rtp-op |
   |                                        | us]                      |
   | a=maxptime:120                         | [RFC4566]                |
   | a=ice-ufrag:c300d85b                   | [RFC5245]                |
   | a=ice-                                 | [RFC5245]                |
   | pwd:de4e99bd291c325921d5d47efbabd9a2   |                          |
   | a=fingerprint:sha-256 6B:8B:F0:65:5F:7 | [RFC5245]                |
   | 8:E2:51:3B:AC:6F:F3:3F:46:1B:35 :DC:B8 |                          |
   | :5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:1 |                          |
   | 9:08                                   |                          |
   | a=setup:active                         | [RFC4145] - Bob carries  |
   |                                        | out DTLS Handshake in    |
   |                                        | parallel                 |
   | a=dtls-id:1                            | [I-D.ietf-mmusic-dtls-sd |
   |                                        | p]                       |
   | a=rtcp-mux                             | [RFC5761]                |
   | a=rtcp-rsize                           | [RFC5506]                |
   | a=rtcp-fb:109 nack                     | [RFC5104]                |
   | a=extmap:1 urn:ietf:params:rtp-hdrext  | [RFC6464]                |
   | :ssrc-audio-level                      |                          |
   | a=candidate:0 1 UDP 2122194687         | [RFC5245]                |
   | 192.168.1.7 51556 typ host             |                          |
   | a=candidate:1 1 UDP 1685987071         | [RFC5245]                |
   | 98.248.92.77 53214 typ srflx raddr     |                          |
   | 192.168.1.7 rport 51556                |                          |
   | a=candidate:0 2 UDP 2122194687         | [RFC5245]                |
   | 192.168.1.7 51558 typ host             |                          |
   | a=candidate:1 2 UDP 1685987071         | [RFC5245]                |
   | 98.248.92.77 60065 typ srflx raddr     |                          |
   | 192.168.1.7 rport 51558                |                          |
   | ****** Video m=line *********          | ************************ |
   |                                        | *****                    |
   | m=video 58679 UDP/TLS/RTP/SAVPF 120    | [RFC4566]                |
   | c=IN IP4 98.248.92.77                  | [RFC4566]                |



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   | a=mid:video                            | [RFC5888]                |
   | a=msid:ma tb                           | Identifies               |
   |                                        | RTCMediaStream ID (ma)   |
   |                                        | and RTCMediaStreamTrack  |
   |                                        | ID (tb)                  |
   | a=sendrecv                             | [RFC3264]                |
   | a=rtpmap:120 VP8/90000                 | [I-D.ietf-payload-vp8]   |
   | a=ice-ufrag:85bC300                    | [RFC5245]                |
   | a=ice-                                 | [RFC5245]                |
   | pwd:325921d5d47efbabd9a2de4e99bd291c   |                          |
   | a=fingerprint:sha-256 6B:8B:F0:65:5F:7 | [RFC5245]                |
   | 8:E2:51:3B:AC:6F:F3:3F:46:1B:35 :DC:B8 |                          |
   | :5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:1 |                          |
   | 9:08                                   |                          |
   | a=setup:active                         | [RFC4145] - Bob carries  |
   |                                        | out DTLS Handshake in    |
   |                                        | parallel                 |
   | a=dtls-id:2                            | [I-D.ietf-mmusic-dtls-sd |
   |                                        | p]                       |
   | a=rtcp-mux                             | [RFC5761]                |
   | a=rtcp-rsize                           | [RFC5506]                |
   | a=rtcp-fb:120 nack                     | [RFC5104]                |
   | a=rtcp-fb:120 nack pli                 | [RFC5104]                |
   | a=rtcp-fb:120 ccm fir                  | [RFC5104]                |
   | a=candidate:0 1 UDP 2122194687         | [RFC5245]                |
   | 192.168.1.7 61556 typ host             |                          |
   | a=candidate:1 1 UDP 1685987071         | [RFC5245]                |
   | 98.248.92.77 58679 typ srflx raddr     |                          |
   | 192.168.1.7 rport 61556                |                          |
   | a=candidate:0 1 UDP 2122194687         | [RFC5245]                |
   | 192.168.1.7 61558 typ host             |                          |
   | a=candidate:1 1 UDP 1685987071         | [RFC5245]                |
   | 98.248.92.77 56507 typ srflx raddr     |                          |
   | 192.168.1.7 rport 61558                |                          |
   +----------------------------------------+--------------------------+

                 Table 18: 5.2.9 SDP Answer without BUNDLE


5.2.10.  Audio, Video BUNDLED, but Data (Not BUNDLED)

   This example show-cases SDP for negotiating a session with Audio,
   Video and data streams between Alice and Bob with data stream not
   being part of the BUNDLE group.  This is shown by assigning unique
   port for data media section and not adding the "mid" identification
   tag to the BUNDLE group.





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          Audio, Video, with Data (Not in BUNDLE)

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |Alice wants to multiplex audio, video but not data    |
   |                                                      |
   |                                                      |
   |  Offer(Audio:Opus Video:VP8, Data(not in BUNDLE))    |
   |----------------------------------------------------->|
   |                                                      |
   |                                                      |
   |       Answer(Audio:Opus Video:VP8, Data)             |
   |<-----------------------------------------------------|
   |                                                      |
   |                                                      |
   |2 Way Call with Audio, Video Multiplexed except data  |
   |......................................................|
   |                                                      |



   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice wants to    |
   |                                   | BUNDLE only audio and video   |
   |                                   | media.                        |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |



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   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 54609 typ host        |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | ****** Application m=line         | ***************************** |
   | *********                         |                               |
   | m=application 10000 UDP/DTLS/SCTP | [I-D.ietf-rtcweb-data-channel |
   | webrtc-datachannel                | ]                             |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:data                        | [RFC5888]                     |
   | a=sctp-port:5000                  | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=max-message-size:100000         | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=sendrecv                        | [RFC3264]                     |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=ice-ufrag:89819013              | [RFC5245]                     |
   | a=ice-pwd:1747d1ee3474af08a068a28 | [RFC5245]                     |
   | a397a4c3f3                        |                               |
   | a=fingerprint:sha-256 29:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |



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   | :04: BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 10000 typ host        |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                        Table 19: 5.2.10 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |



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   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.7 49203 typ host        |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | ****** Application m=line         | ***************************** |
   | *********                         |                               |
   | m=application 20000 UDP/DTLS/SCTP | [I-D.ietf-mmusic-sctp-sdp]    |
   | webrtc-datachannel                |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:data                        | [RFC5888]                     |
   | a=sctp-port:5000                  | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=max-message-size:100000         | [I-D.ietf-mmusic-sctp-sdp]    |
   | a=setup:active                    | [RFC4145]                     |
   | a=sendrecv                        | [RFC3264]                     |
   | a=ice-ufrag:991Ca2a5e             | [RFC5245]                     |
   | a=ice-pwd:921d5d47efbabd9a2de4e99 | [RFC5245]                     |
   | bd291c325                         |                               |
   | a=fingerprint:sha-256 7B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35: DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.7 20000 typ host        |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                        Table 20: 5.2.10 SDP Answer









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5.2.11.  Audio Only, Add Video to BUNDLE

   This example involves 2 Offer/Answer exchanges.  First one is used to
   negotiate and setup BUNDLE support for Audio-only session followed by
   an updated Offer/Answer exchange to add video stream to the ongoing
   session.  Also the newly added video stream is BUNDLED with the audio
   stream.



            Audio Only , Add Video and BUNDLE

   Alice                                                 Bob
   |                                                      |
   |                                                      |
   |        Alice indicates support for BUNDLE            |
   |                                                      |
   |                Offer(Audio:Opus)                     |
   |----------------------------------------------------->|
   |                                                      |Bob
   |                                                      |supports
   |                                                      |BUNDLE
   |                Answer(Audio:Opus)                    |
   |<-----------------------------------------------------|
   |                                                      |Alice adds
   |                                                      |video stream
   |        Updated Offer(Audio:Opus, Video:VP8)          |to BUNDLE
   |----------------------------------------------------->|
   |                                                      |
   |                                                      |Bob accepts
   |        Updated Answer(Audio:Opus, Video:VP8)         |
   |<-----------------------------------------------------|
   |                                                      |
   |   2Way Call with Audio and Video Multiplexed         |
   |......................................................|
   |                                                      |
   |                                                      |














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   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice adds audio  |
   |                                   | m=line to the BUNDLE group    |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                        Table 21: 5.2.11 SDP Offer



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   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP 1694302207    | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                        Table 22: 5.2.10 SDP Answer




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   +-----------------------------------+-------------------------------+
   | Updated Offer SDP Contents        | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | Version number incremented    |
   |                                   | [RFC4566]                     |
   | o=- 20518 1 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]Ali |
   |                                   | ce want's to use the same     |
   |                                   | DTLS association              |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |



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   | m=video 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                    Table 23: 5.2.11 SDP Updated Offer


   +-----------------------------------+-------------------------------+
   | Updated Answer SDP Contents       | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566] Version number      |
   |                                   | incremented                   |
   | o=-  16833 1 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio video        | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS audio video            | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |



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   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]Bob |
   |                                   | agrees to use the same DTLS   |
   |                                   | association                   |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP 1694302207    | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 120                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:video                       | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:120 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtcp-fb:120 nack                | [RFC5104]                     |
   | a=rtcp-fb:120 nack pli            | [RFC5104]                     |
   | a=rtcp-fb:120 ccm fir             | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                    Table 24: 5.2.11 SDP Updated Answer


5.3.  MultiResolution, RTX, FEC Examples

   This section deals with scenarios related to multi-source, multi-
   stream negotiation such as layered coding, simulcast, along with
   techniques that deal with providing robustness against transmission
   errors such as FEC and RTX.  Also to note, mechanisms such as FEC and
   RTX could be envisioned in the above basic scenarios as well.





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5.3.1.  Sendonly Simulcast Session with 2 cameras and 2 encodings per
        camera

   The SDP below shows Offer/Answer exchange with one audio and two
   video sources.  Each of the video source can be sent at two different
   resolutions.

   One video source corresponds to VP8 encoding, while the other
   corresponds to H.264 encoding.

   [I-D.ietf-mmusic-rid] framework is used to further constrain the
   media format encodings and map the payload types (PT) to the 'rid'
   identifiers.

   [I-D.ietf-mmusic-sdp-simulcast] framework identifies the simulcast
   streams via their 'rid' identifiers.

   bundle-only attribute is used for the video sources in the Offer to
   ensure enabling video sources in the context of BUNDLE alone.

   BUNDLE grouping framework enables multiplexing of all the 5 streams
   (1 audio stream + 4 video streams) over a single RTP Session.


          1 Way Successful Simulcast w/BUNDLE

   Alice                                            Bob
   |                                                 |
   |                                                 |
   |     Alice offers 2 sendonly video sources       |
   |     with 2 simulcast encodings per source       |
   |           and bundle-only for video             |
   |                                                 |
   |                                                 |
   |   Offer(Audio:Opus,Video1:VP8,Video2:H.264)     |
   |------------------------------------------------>|
   |                                                 |
   |                                                 |
   |    Answer(Audio:Opus Video1:VP8,Video2:H.264)   |
   |<------------------------------------------------|
   |                                                 |
   |One-Way 1 Opus, 2 H.264 and 2 VP8 video streams, |
   | all multiplexed                                 |
   |.................................................|
   |                                                 |
   |                                                 |





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   +-------------------------------------+-----------------------------+
   | Offer SDP Contents                  | RFC#/Notes                  |
   +-------------------------------------+-----------------------------+
   | v=0                                 | [RFC4566]                   |
   | o=- 20519 0 IN IP4 0.0.0.0          | [RFC4566]                   |
   | s=-                                 | [RFC4566]                   |
   | t=0 0                               | [RFC4566]                   |
   | a=group:BUNDLE m0 m1 m2             | [I-D.ietf-mmusic-sdp-bundle |
   |                                     | -negotiation] Alice         |
   |                                     | supports grouping of        |
   |                                     | m=lines under BUNDLE        |
   |                                     | semantics                   |
   | a=group:LS m0 m1                    | [RFC5888]                   |
   | a=ice-options:trickle               | [I-D.ietf-mmusic-trickle-ic |
   |                                     | e]                          |
   | ****** Audio m=line *********       | *************************** |
   |                                     | **                          |
   | m=audio 54609 UDP/TLS/RTP/SAVPF 109 | [RFC4566]                   |
   | c=IN IP4 24.23.204.141              | [RFC4566]                   |
   | a=mid:m0                            | [RFC5888]                   |
   | a=msid:ma ta                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (ta) |
   | a=sendonly                          | [RFC3264]                   |
   | a=rtpmap:109 opus/48000/2           | [I-D.ietf-payload-rtp-opus] |
   | a=maxptime:120                      | [RFC4566]                   |
   | a=ice-ufrag:074c6550                | [RFC5245]                   |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474 | [RFC5245]                   |
   | af08a068                            |                             |
   | a=fingerprint:sha-256 19:E2:1C:3B:4 | [RFC5245]                   |
   | B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04  |                             |
   | :BB:05:2F:70:9F:04:A9:0E:05:E9:26:3 |                             |
   | 3:E8:70:88:A2                       |                             |
   | a=setup:actpass                     | [RFC4145]                   |
   | a=dtls-id:1                         | [I-D.ietf-mmusic-dtls-sdp]  |
   | a=rtcp-mux                          | [RFC5761]                   |
   | a=rtcp:54609 IN IP4 24.23.204.141   | [RFC3605]                   |
   | a=rtcp-rsize                        | [RFC5506]                   |
   | a=rtcp-fb:109 nack                  | [RFC5104]                   |
   | a=extmap:1 urn:ietf:params:rtp-     | [RFC6464]                   |
   | hdrext:ssrc-audio-level             |                             |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | a=candidate:0 1 UDP  2113667327     | [RFC5245]                   |
   | 192.168.1.4 61665 typ host          |                             |
   | a=candidate:1 1 UDP  694302207      | [RFC5245]                   |
   | 24.23.204.141 54609 typ srflx raddr |                             |
   | 192.168.1.4 rport 61665             |                             |



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   | a=end-of-candidates                 | [I-D.ietf-mmusic-trickle-ic |
   |                                     | e]                          |
   | ****** Video-1 m=line *********     | *************************** |
   |                                     | **                          |
   | m=video 0 UDP/TLS/RTP/SAVPF 98 100  | bundle-only video line with |
   |                                     | port number set to zero     |
   | c=IN IP4 24.23.204.141              | [RFC4566]                   |
   | a=bundle-only                       | [I-D.ietf-mmusic-sdp-bundle |
   |                                     | -negotiation]               |
   | a=mid:m1                            | [RFC5888] Video m=line part |
   |                                     | of BUNDLE group             |
   | a=msid:ma tb                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (tb) |
   | a=sendonly                          | [RFC3264] - Send only video |
   |                                     | stream                      |
   | a=rtpmap:98 VP8/90000               | [I-D.ietf-payload-vp8]      |
   | a=fmtp:98 max-fr=30                 | [RFC4566]                   |
   | a=rtpmap:100 VP8/90000              | [I-D.ietf-payload-vp8]      |
   | a=fmtp:100 max-fr=15                | [RFC4566]                   |
   | a=rtcp-fb:* nack                    | [RFC5104]                   |
   | a=rtcp-fb:* nack pli                | [RFC5104]                   |
   | a=rtcp-fb:* ccm fir                 | [RFC5104]                   |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | a=rid:1 send pt=98;max-width=1280   | [I-D.ietf-mmusic-rid] 1:1   |
   | ;max-height=720;                    | rid mapping to payload type |
   |                                     | and specify resolution      |
   |                                     | constraints                 |
   | a=rid:2 send pt=100;max-width=640   | [I-D.ietf-mmusic-rid] 1:1   |
   | ;max-height=480;                    | rid mapping to payload type |
   |                                     | and specify resolution      |
   |                                     | constraints                 |
   | a=simulcast: send 1;~2              | [I-D.ietf-mmusic-sdp-simulc |
   |                                     | ast] Alice can send 2       |
   |                                     | resolutions identified by   |
   |                                     | the 'rid' identifiers Also, |
   |                                     | the second stream is        |
   |                                     | initially paused.           |
   | ****** Video-2 m=line *********     | *************************** |
   |                                     | **                          |
   | m=video 0 UDP/TLS/RTP/SAVPF 101 102 | bundle-only video line with |
   |                                     | port number set to zero     |
   | c=IN IP4 24.23.204.141              | [RFC4566]                   |
   | a=bundle-only                       | [I-D.ietf-mmusic-sdp-bundle |
   |                                     | -negotiation]               |
   | a=mid:m2                            | [RFC5888] Video m=line part |
   |                                     | of BUNDLE group             |



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   | a=msid:ma tc                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (tc) |
   | a=sendonly                          | [RFC3264] - Send only video |
   |                                     | stream                      |
   | a=rtpmap:101 H264/90000             | [RFC3984]                   |
   | a=rtpmap:102 H264/90000             | [RFC3984]                   |
   | a=fmtp:101 profile-level-id=42401f  | [RFC3984]Camera-2,Encoding- |
   | ;packetization-mode=0;max-fr=30     | 1                           |
   | a=fmtp:102 profile-level-id=42401f  | [RFC3984]Camera-2,Encoding- |
   | ;packetization-mode=1;max-fr=15     | 2                           |
   | a=rtcp-fb:* nack                    | [RFC5104]                   |
   | a=rtcp-fb:* nack pli                | [RFC5104]                   |
   | a=rtcp-fb:*  ccm fir                | [RFC5104]                   |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | a=rid:3 send pt=101;max-width=1280  | [I-D.ietf-mmusic-rid] 1:1   |
   | ;max-height=720;                    | rid mapping to payload type |
   |                                     | and specify resolution      |
   |                                     | constraints                 |
   | a=rid:4 send pt=102;max-width=640   | [I-D.ietf-mmusic-rid] 1:1   |
   | ;max-height=360;                    | rid mapping to payload type |
   |                                     | and specify resolution      |
   |                                     | constraints                 |
   | a=simulcast: send 3;4               | [I-D.ietf-mmusic-sdp-simulc |
   |                                     | ast] Alice can send 2       |
   |                                     | resolutions identified by   |
   |                                     | the 'rid' identifiers       |
   +-------------------------------------+-----------------------------+

                         Table 25: 5.3.1 SDP Offer


   +-------------------------------------+-----------------------------+
   | Answer SDP Contents                 | RFC#/Notes                  |
   +-------------------------------------+-----------------------------+
   | v=0                                 | [RFC4566]                   |
   | o=- 20519 0 IN IP4 0.0.0.0          | [RFC4566]                   |
   | s=-                                 | [RFC4566]                   |
   | t=0 0                               | [RFC4566]                   |
   | a=group:BUNDLE m0 m1 m2             | [I-D.ietf-mmusic-sdp-bundle |
   |                                     | -negotiation] Alice         |
   |                                     | supports grouping of        |
   |                                     | m=lines under BUNDLE        |
   |                                     | semantics                   |
   | a=group:LS m0 m1                    | [RFC5888]                   |
   | a=ice-options:trickle               | [I-D.ietf-mmusic-trickle-ic |
   |                                     | e]                          |



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   | ****** Audio m=line *********       | *************************** |
   |                                     | **                          |
   | m=audio 49203 UDP/TLS/RTP/SAVPF 109 | [RFC4566]                   |
   | c=IN IP4 98.248.92.77               | [RFC4566]                   |
   | a=mid:m0                            | [RFC5888]                   |
   | a=msid:ma ta                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (ta) |
   | a=recvonly                          | [RFC3264]                   |
   | a=rtpmap:109 opus/48000/2           | [I-D.ietf-payload-rtp-opus] |
   | a=rtcp-fb:109 nack                  | [RFC5104]                   |
   | a=maxptime:120                      | [RFC4566]                   |
   | a=ice-ufrag:c300d85b                | [RFC5245]                   |
   | a=ice-pwd:de4e99bd291c325921d5d47ef | [RFC5245]                   |
   | babd9a2                             |                             |
   | a=fingerprint:sha-256 6B:8B:F0:65:5 | [RFC5245]                   |
   | F:78:E2:51:3B:AC:6F:F3:3F:46:1B:35  |                             |
   | :DC:B8:5F:64:1A:24:C2:43:F0:A1:58:D |                             |
   | 0:A1:2C:19:08                       |                             |
   | a=setup:active                      | [RFC4145]                   |
   | a=dtls-id:1                         | [I-D.ietf-mmusic-dtls-sdp]  |
   | a=rtcp-mux                          | [RFC5761]                   |
   | a=rtcp-rsize                        | [RFC5506]                   |
   | a=extmap:1 urn:ietf:params:rtp-     | [RFC6464]                   |
   | hdrext:ssrc-audio-level             |                             |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | a=candidate:0 1 UDP  2113667327     | [RFC5245]                   |
   | 192.168.1.7 61665 typ host          |                             |
   | a=candidate:1 1 UDP  694302207      | [RFC5245]                   |
   | 98.248.92.77 49203 typ srflx raddr  |                             |
   | 192.168.1.4 rport 61665             |                             |
   | a=end-of-candidates                 | [I-D.ietf-mmusic-trickle-ic |
   |                                     | e]                          |
   | ****** Video-1 m=line *********     | *************************** |
   |                                     | **                          |
   | m=video 49203 UDP/TLS/RTP/SAVPF 98  | BUNDLE accepted with port   |
   | 100                                 | repeated from the audio     |
   |                                     | port                        |
   | c=IN IP4 98.248.92.77               | [RFC4566]                   |
   | a=mid:m1                            | [RFC5888] Video m=line part |
   |                                     | of BUNDLE group             |
   | a=msid:ma tb                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (tb) |
   | a=recvonly                          | [RFC3264] - receive only    |
   |                                     | video stream                |
   | a=rtpmap:98 VP8/90000               | [I-D.ietf-payload-vp8]      |



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   | a=rtpmap:100 VP8/90000              | [I-D.ietf-payload-vp8]      |
   | a=fmtp:98 max-fr=30                 | [RFC4566]                   |
   | a=fmtp:100 max-fr=15                | [RFC4566]                   |
   | a=rtcp-fb:* nack                    | [RFC5104]                   |
   | a=rtcp-fb:* nack pli                | [RFC5104]                   |
   | a=rtcp-fb:* ccm fir                 | [RFC5104]                   |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | a=rid:1 recv pt=98;max-width=1280   | [I-D.ietf-mmusic-rid] Bob   |
   | ;max-height=720;                    | accepts the offered payload |
   |                                     | format constraints          |
   | a=rid:2 recv pt=100;max-width=640   | [I-D.ietf-mmusic-rid] Bob   |
   | ;max-height=480;                    | accepts the offered payload |
   |                                     | format constraints          |
   | a=simulcast: recv 1;2               | [I-D.ietf-mmusic-sdp-simulc |
   |                                     | ast] Bob accepts the        |
   |                                     | offered simulcast streams   |
   |                                     | and removes the paused      |
   |                                     | state of stream with 'rid'  |
   |                                     | value 2.                    |
   | ****** Video-2 m=line *********     | *************************** |
   |                                     | **                          |
   | m=video 49203 UDP/TLS/RTP/SAVPF 101 | BUNDLE accepted with port   |
   | 102                                 | repeated from the audio     |
   |                                     | port                        |
   | c=IN IP4 98.248.92.77               | [RFC4566]                   |
   | a=mid:m2                            | [RFC5888] Video m=line part |
   |                                     | of BUNDLE group             |
   | a=msid:ma tc                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (tc) |
   | a=recvonly                          | [RFC3264]                   |
   | a=rtpmap:101 H264/90000             | [RFC3984]                   |
   | a=rtpmap:102 H264/90000             | [RFC3984]                   |
   | a=fmtp:101 profile-level-id=42401f  | [RFC3984]                   |
   | ;packetization-mode=1;max-fr=30     |                             |
   | a=fmtp:102 profile-level-id=42401f  | [RFC3984]                   |
   | ;packetization-mode=1;max-fr=15     |                             |
   | a=rtcp-fb:* nack                    | [RFC5104]                   |
   | a=rtcp-fb:* nack pli                | [RFC5104]                   |
   | a=rtcp-fb:*  ccm fir                | [RFC5104]                   |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | a=rid:3 recv pt=101;max-width=1280  | [I-D.ietf-mmusic-rid] Bob   |
   | ;max-height=720;                    | accepts the offered payload |
   |                                     | format constraints          |
   | a=rid:4 recv pt=102;max-width=640   | [I-D.ietf-mmusic-rid] Bob   |
   | ;max-height=360;                    | accepts the offered payload |



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   |                                     | format constraints          |
   | a=simulcast: recv 3;4               | [I-D.ietf-mmusic-sdp-simulc |
   |                                     | ast] Bob accepts the        |
   |                                     | offered simulcast streams.  |
   +-------------------------------------+-----------------------------+

                        Table 26: 5.3.1 SDP Answer


5.3.2.  Successful SVC Video Session

   This section shows an SDP Offer/Answer for a session with an audio
   and a single video source.  The video source is encoded as layered
   coding at 3 different resolutions based on [RFC5583].  The video
   m=line shows 3 streams with last stream (payload 100) dependent on
   streams with payload 96 and 97 for decoding.


          SVC Session - 3 Layers w/BUNDLE

  Alice                                            Bob
  |                                                 |
  |                                                 |
  |      Alice offers 3 sendonly video streams      |
  |      as 3 layers of SVC and bundle-only         |
  |               for video streams.                |
  |                                                 |
  |            Offer(Video:H.264 SVC)               |
  |------------------------------------------------>|
  |                                                 |
  |                                                 |Bob accepts Alice's
  |                                                 |offered Codec
  |                                                 |operation points
  |                                                 |
  |             Answer(Video:H.264)                 |
  |<------------------------------------------------|
  |                                                 |
  |One-Way  H.264 SVC video streams                 |
  |.................................................|
  |                                                 |
  |                                                 |



   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |



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   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice supports    |
   |                                   | grouping of m=lines under     |
   |                                   | BUNDLE semantics              |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888] Audio m=line part   |
   |                                   | of BUNDLE group with a unique |
   |                                   | port number                   |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 0 UDP/TLS/RTP/SAVPF 96 97 | bundle-only video line with   |
   | 100                               | port number set to zero       |



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   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=bundle-only                     | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=mid:m1                          | [RFC5888] Video m=line part   |
   |                                   | of BUNDLE group               |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tc)                       |
   | a=sendonly                        | [RFC3264] - Send only video   |
   |                                   | stream                        |
   | a=rtpmap:96 H264/90000            | [RFC3984]                     |
   | a=fmtp:96 profile-level-          | [RFC3984]H.264 Layer 1        |
   | id=4d0028; packetization-mode=1   |                               |
   | ;max-fr=30;max-fs=8040            |                               |
   | a=rtpmap:97 H264/90000            | [RFC3984]                     |
   | a=fmtp:97 profile-level-id=4d0028 | [RFC3984] H.264 Layer 2       |
   | ;packetization-mode=1; max-fr=15  |                               |
   | ;max-fs=1200                      |                               |
   | a=rtpmap:100 H264-SVC/90000       | [RFC3984]                     |
   | a=fmtp:100 profile-level-         | [RFC3984]                     |
   | id=4d0028;packetization-mode=1;   |                               |
   | max-fr=30;max-fs=8040             |                               |
   | a=depend:100 lay m1:96,97;        | [RFC5583]Layer 3 dependent on |
   |                                   | layers 1 and 2                |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=rtcp-fb:* nack pli              | [RFC5104]                     |
   | a=rtcp-fb:* ccm fir               | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                    Table 27: 5.3.2 SDP Offer with SVC


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |



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   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667326    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP  1694302206   | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.5 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | BUNDLE accepted Bundle        |
   | 96 100                            | address same as audio m=line. |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m1                          | [RFC5888] Video m=line part   |
   |                                   | of BUNDLE group               |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=recvonly                        | [RFC3264] - Receive only      |
   |                                   | video stream                  |
   | a=rtpmap:96 H264/90000            | [RFC3984]                     |
   | a=fmtp:96 profile-level-id=4d0028 | [RFC3984]H.264 Layer 1        |
   | ;packetization-mode=1; max-fr=30  |                               |
   | ;max-fs=8040                      |                               |
   | a=rtpmap:100 H264-SVC/90000       | [RFC3984]                     |
   | a=fmtp:100 profile-level-         | [RFC3984]                     |
   | id=4d0028;packetization-mode=1;   |                               |



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   | max-fr=30;max-fs=8040             |                               |
   | a=depend:100 lay m1:96;           | [RFC5583] Bob chooses 2 Codec |
   |                                   | Operation points              |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=rtcp-fb:* nack pli              | [RFC5104]                     |
   | a=rtcp-fb:* ccm fir               | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   +-----------------------------------+-------------------------------+

                    Table 28: 5.3.2 SDP Answer with SVC


5.3.3.  Successful Simulcast Video Session with Retransmission

   This section shows an SDP Offer/Answer exchange for a simulcast
   scenario with 3 resolutions and has [RFC4588] style re-transmission
   flows.

   [I-D.ietf-mmusic-rid] framework is used to specify all the (3)
   resolution constraints mapped to a single Payload Type (98).

   [I-D.ietf-mmusic-sdp-simulcast] framework identifies the simulcast
   streams via their 'rid' identifiers.



























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           Simulcast Streams with Retransmission

   Alice                                                    Bob
   |                                                         |
   |                                                         |
   |Alice offers single audio and simulcasted video streams  |
   |                                                         |
   |                                                         |
   |    Offer(Audio:Opus Video:VP8 with 3 resolutions)       |
   |    & RTX stream                                         |
   |-------------------------------------------------------->|
   |                                                         |
   |                                                         |
   |          Answer (Bob accepts Alice's offer)             |
   |<--------------------------------------------------------|
   |                                                         |
   |                                                         |
   |One-Way 1 Opus, 3 VP8 and RTX video streams,all muxed    |
   |.........................................................|
   |                                                         |
   |                                                         |


   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice supports    |
   |                                   | grouping of m=lines under     |
   |                                   | BUNDLE semantics              |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888] Audio m=line part   |
   |                                   | of BUNDLE group with a unique |
   |                                   | port number                   |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |



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   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 0 UDP/TLS/RTP/SAVPF 98    | bundle-only video line with   |
   | 103                               | port number set to zero       |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=bundle-only                     | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=mid:m1                          | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=sendonly                        | [RFC3264]                     |
   | a=rtpmap:98 VP8/90000             | [I-D.ietf-payload-vp8]        |
   | a=fmtp:98 max-fr=30               | [RFC4566]                     |
   | a=rtpmap:103 rtx/90000            | [RFC4588]                     |
   | a=fmtp:103 apt=98;rtx-time=200    | [RFC4588]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=rtcp-fb:* nack pli              | [RFC5104]                     |
   | a=rtcp-fb:* ccm fir               | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=rid:1 send pt=98;max-fs=921600  | [I-D.ietf-mmusic-rid]         |
   | ;max-fr=30;                       |                               |
   | a=rid:2 send pt=98;max-fs=614400  | [I-D.ietf-mmusic-rid]         |
   | ;max-fr=15;                       |                               |



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   | a=rid:3 send pt=98;max-fs=230400  | [I-D.ietf-mmusic-rid]         |
   | ;max-fr=30;                       |                               |
   | a=simulcast: send 1;2;3           | [I-D.ietf-mmusic-sdp-simulcas |
   |                                   | t] Alice can send all the     |
   |                                   | simulcast streams             |
   +-----------------------------------+-------------------------------+

                Table 29: 5.3.3 SDP Offer w/Simulcast, RTX


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Bob supports      |
   |                                   | grouping of m=lines under     |
   |                                   | BUNDLE semantics              |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |



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   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667326    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP  1694302206   | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | BUNDLE accepted with Bundle   |
   | 98 100 101 103                    | address identical to audio    |
   |                                   | m-line                        |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m1                          | [RFC5888] Video m=line part   |
   |                                   | of BUNDLE group               |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:98 VP8/90000             | [I-D.ietf-payload-vp8]        |
   | a=fmtp:98 max-fr=30               | [RFC4566]                     |
   | a=rtpmap:103 rtx/90000            | [RFC4588]                     |
   | a=fmtp:103 apt=98;rtx-time=200    | [RFC4588]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=rtcp-fb:* nack pli              | [RFC5104]                     |
   | a=rtcp-fb:* ccm fir               | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=rid:1 recv pt=98;max-fs=921600  | [I-D.ietf-mmusic-rid]         |
   | ;max-fr=30;                       |                               |
   | a=rid:2 recv pt=98;max-fs=614400  | [I-D.ietf-mmusic-rid]         |
   | ;max-fr=15;                       |                               |
   | a=rid:3 recv pt=98;max-fs=230400  | [I-D.ietf-mmusic-rid]         |
   | ;max-fr=30;                       |                               |
   | a=simulcast: recv 1;2;3           | [I-D.ietf-mmusic-sdp-simulcas |
   |                                   | t] Bob accepts the offered    |
   |                                   | simulcast streams             |
   +-----------------------------------+-------------------------------+

                Table 30: 5.3.3 SDP Answer w/Simulcast, RTX


5.3.4.  Successful 1-way Simulcast Session with 2 resolutions and RTX -
        One resolution rejected

   This section shows an SDP Offer/Answer exchange for a simulcast
   scenario with 2 two resolutions.




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   It also showcases where Bob rejects one of the Simulcast Video Stream
   which results in the rejection of the associated repair stream
   implicitly.



     Simulcast Streams with Retransmission Rejected

Alice                                                    Bob
|                                                         |
|                                                         |
|Alice offers single audio and simulcasted video streams  |
| with bundle-only for video                              |
|                                                         |
|                                                         |
|Offer(Audio:Opus Video:VP8 with 2 resolutions,RTX Stream)|
|-------------------------------------------------------->|
|                                                         |
|                                                         |Bob accepts 1
|                                                         |simulcast,rtx
|                                                         |rejects the
|                                                         |other
|   Answer(Audio:Opus Video:VP8 with 1 res & RTX Stream)  |
|<--------------------------------------------------------|
|                                                         |
|                                                         |
|1-way audio,video session and its associated RTX stream, |
| all multiplexed                                         |
|.........................................................|
|                                                         |
|                                                         |



   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice supports    |
   |                                   | grouping of m=lines under     |
   |                                   | BUNDLE semantics              |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |



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   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 0 UDP/TLS/RTP/SAVPF 98    | bundle-only video line with   |
   | 100 101 103                       | port number set to zero       |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=bundle-only                     | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=mid:m1                          | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb                        |
   | a=sendonly                        | [RFC3264]                     |
   | a=rtpmap:98 VP8/90000             | [I-D.ietf-payload-vp8]        |
   | a=rtpmap:100 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtpmap:101 rtx/90000            | [RFC4588]                     |
   | a=rtpmap:103 rtx/90000            | [RFC4588]                     |



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   | a=fmtp:98 max-fr=30;max-fs=8040   | [RFC4566]                     |
   | a=fmtp:100 max-fr=15;max-fs=1200  | [RFC4566]                     |
   | a=fmtp:101 apt=98;rtx-time=200    | [RFC4588]                     |
   | a=fmtp:103 apt=100;rtx-time=200   | [RFC4588]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=rtcp-fb:* nack pli              | [RFC5104]                     |
   | a=rtcp-fb:* ccm fir               | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=rid:1 send pt=98;               | [I-D.ietf-mmusic-rid] 1:1     |
   |                                   | mapping between the PT and    |
   |                                   | the 'rid' identifier          |
   | a=rid:2 send pt=100;              | [I-D.ietf-mmusic-rid] 1:1     |
   |                                   | mapping between the PT and    |
   |                                   | the 'rid' identifier          |
   | a=simulcast: send 1;2             | [I-D.ietf-mmusic-sdp-simulcas |
   |                                   | t]                            |
   +-----------------------------------+-------------------------------+

                Table 31: 5.3.4 SDP Offer w/Simulcast, RTX


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Bob supports      |
   |                                   | grouping of m=lines under     |
   |                                   | BUNDLE semantics              |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |



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   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667326    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP  1694302206   | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | BUNDLE accepted with Bundle   |
   | 98 101                            | address identical to audio    |
   |                                   | m-line                        |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m1                          | [RFC5888]                     |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:98 VP8/90000             | [I-D.ietf-payload-vp8]        |
   | a=rtpmap:101 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=fmtp:98 max-fr=30;max-fs=8040   | [RFC4566]                     |
   | a=fmtp:101 apt=98;rtx-time=200    | [RFC4588]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=rid:1 recv pt=98;               | [I-D.ietf-mmusic-rid]         |
   | a=simulcast: recv 1               | [I-D.ietf-mmusic-sdp-simulcas |
   |                                   | t] Bob rejects the second     |
   |                                   | simulcast stream and the      |
   |                                   | associated rtx stream.        |
   +-----------------------------------+-------------------------------+

            Table 32: 5.3.4 SDP Answer (one Simulcast Rejected)








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5.3.5.  Simulcast Video Session with Forward Error Correction

   This section shows an SDP Offer/Answer exchange for Simulcast video
   stream at two resolutions and and has [RFC5956] style FEC flows.

   On completion of the Offer/Answer exchange mechanism we end up one
   audio stream, 2 simulcast video streams and 2 associated FEC streams
   are sent over a single 5-tuple.


      Simulcast Streams with Forward Error Correction

Alice                                                            Bob
|                                                               |
|                                                               |
|                                                               |
|Alice offers single audio and simulcasted video streams        |
|with bundle-only                                               |
|                                                               |
|                                                               |
|Offer(Audio:Opus Video:VP8 with 2 resolutions with FEC Streams)|
|-------------------------------------------------------------->|
|                                                               |
|                                                               |Bob
|                                                               |accepts
|                                                               |Alice's
|                                                               |offer
|Answer(Audio:Opus Video:VP8 with 2 resolutions w/FEC Streams)  |
|<--------------------------------------------------------------|
|                                                               |
|One-Way Audio,Video session with 4 video streams(Simulcast     |
| and FEC) all multiplexed                                      |
|...............................................................|
|                                                               |
|                                                               |
|                                                               |


   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation] Alice supports    |
   |                                   | grouping of m=lines under     |



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   |                                   | BUNDLE semantics              |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 0 UDP/TLS/RTP/SAVPF 98    | bundle-only video line with   |
   | 100 101 103                       | port number set to zero       |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=bundle-only                     | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=mid:m1                          | [RFC5888] Video m=line part   |
   |                                   | of BUNDLE group               |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |



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   | a=sendonly                        | [RFC3264]                     |
   | a=rtpmap:98 VP8/90000             | [I-D.ietf-payload-vp8]        |
   | a=rtpmap:100 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtpmap:101 flexfec/90000        | [I-D.ietf-payload-flexible-fe |
   |                                   | c-scheme]                     |
   | a=rtpmap:103 flexfec/90000        | [I-D.ietf-payload-flexible-fe |
   |                                   | c-scheme]                     |
   | a=fmtp:98 max-fr=30;max-fs=8040   | [RFC4566]                     |
   | a=fmtp:100 max-fr=15;max-fs=1200  | [RFC4566]                     |
   | a=fmtp:101 L=5; D=10; ToP=2;      | [I-D.ietf-payload-flexible-fe |
   | repair-window=200000              | c-scheme]                     |
   | a=fmtp:103 L=5; D=10; ToP=2;      | [I-D.ietf-payload-flexible-fe |
   | repair-window=200000              | c-scheme]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=rtcp-fb:* nack pli              | [RFC5104]                     |
   | a=rtcp-fb:* ccm fir               | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=rid:1 send pt=98;               | [I-D.ietf-mmusic-rid] 1:1     |
   |                                   | mapping between the PT and    |
   |                                   | the 'rid' identifier          |
   | a=rid:2 send pt=100;              | [I-D.ietf-mmusic-rid] 1:1     |
   |                                   | mapping between the PT and    |
   |                                   | the 'rid' identifier          |
   | a=simulcast: send 1;2             | [I-D.ietf-mmusic-sdp-simulcas |
   |                                   | t]                            |
   +-----------------------------------+-------------------------------+

                         Table 33: 5.3.5 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20519 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE m0 m1              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=group:LS m0 m1                  | [RFC5888]                     |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109                               |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m0                          | [RFC5888] Audio m=line part   |
   |                                   | of BUNDLE group with a unique |



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   |                                   | port number                   |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:109 nack                | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667326    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP  1694302206   | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Video m=line *********     | ***************************** |
   | m=video 49203 UDP/TLS/RTP/SAVPF   | BUNDLE accepted with Bundle   |
   | 98 100 101 103                    | Address identical to audio    |
   |                                   | m=line.                       |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:m1                          | [RFC5888] Video m=line part   |
   |                                   | of BUNDLE group               |
   | a=msid:ma tb                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (tb)                       |
   | a=recvonly                        | [RFC3264]                     |
   | a=rtpmap:98 VP8/90000             | [I-D.ietf-payload-vp8]        |
   | a=rtpmap:100 VP8/90000            | [I-D.ietf-payload-vp8]        |
   | a=rtpmap:101 flexfec/90000        | [I-D.ietf-payload-flexible-fe |
   |                                   | c-scheme]                     |
   | a=rtpmap:103 flexfec/90000        | [I-D.ietf-payload-flexible-fe |
   |                                   | c-scheme]                     |
   | a=fmtp:98 max-fr=30;max-fs=8040   | [RFC4566]                     |
   | a=fmtp:100 max-fr=15;max-fs=1200  | [RFC4566]                     |



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   | a=fmtp:101 L=5; D=10; ToP=2;      | [I-D.ietf-payload-flexible-fe |
   | repair-window=200000              | c-scheme]                     |
   | a=fmtp:103 L=5; D=10; ToP=2;      | [I-D.ietf-payload-flexible-fe |
   | repair-window=200000              | c-scheme]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=rtcp-fb:* nack pli              | [RFC5104]                     |
   | a=rtcp-fb:* ccm fir               | [RFC5104]                     |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=rid:1 recv pt=98;               | [I-D.ietf-mmusic-rid]         |
   | a=rid:2 recv pt=100;              | [I-D.ietf-mmusic-rid]         |
   | a=simulcast: recv 1;2             | [I-D.ietf-mmusic-sdp-simulcas |
   |                                   | t]                            |
   +-----------------------------------+-------------------------------+

                        Table 34: 5.3.5 SDP Answer


5.4.  Others

   The examples in the section provide SDP Offer/Answer exchange for a
   variety of scenarios related to RTP Header extension for conference
   usages, Legacy Interop scenarios and more.

5.4.1.  Audio Session - Voice Activity Detection

   This example shows Alice indicating the support of the RTP header
   extension to include the audio-level of the audio sample carried in
   the RTP packet.






















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              2-Way Audio with VAD

    Alice                                    Bob
    |                                         |
    |                                         |
    |Alice indicates support for including    |
    |audio level in RTP header                |
    |                                         |
    |     Offer(Audio:Opus,PCMU,PCMA)         |
    |---------------------------------------->|
    |                                         |
    |                                         |
    |     Answer(Audio:Opus,PCMU,PCMA)        |
    |<----------------------------------------|
    |                                         |
    |                                         |Bob accepts and
    |                                         |indicates his
    |                                         |support as well
    |                                         |
    |     Two way Opus Audio                  |
    |.........................................|
    |                                         |
    |Per packet audio-level is included in the|
    |RTP header                               |
    |                                         |



   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109 0 8                           |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |



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   | a=rtpmap:0 PCMU/8000              | [RFC3551]                     |
   | a=rtpmap:8 PCMA/8000              | [RFC3551]                     |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                         Table 35: 5.4.1 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566]                     |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109 0 98                          |                               |
   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |



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   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264] - Bob can send and  |
   |                                   | recv audio                    |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus] - |
   |                                   | Bob accepts only Opus Codec   |
   | a=rtpmap:0 PCMU/8000              | [RFC3551] PCMU Audio Codec    |
   | a=rtpmap:0 PCMA/8000              | [RFC3551] PCMA Audio Codec    |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761] - Bob can perform   |
   |                                   | RTP/RTCP Muxing on port 49203 |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=extmap:1 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP 1694302207    | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                        Table 36: 5.4.1 SDP Answer


5.4.2.  Audio Conference - Voice Activity Detection

   This example shows SDP for RTP header extension that allows RTP-level
   mixers in audio conferences to deliver information about the audio
   level of individual participants.










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        Audio Conference with VAD Support

   Alice                                    Mixer
   |                                         |
   |Alice indicates her interest to audio    |
   |levels for the contributing sources      |
   |                                         |
   |Offer(Audio:Opus,PCMU,PCMA)              |
   |---------------------------------------->|
   |                                         |
   |                                         |
   |Answer(Audio:Opus,PCMU,PCMA)             |
   |<----------------------------------------|
   |                                         |
   |                                         |Mixer indicates
   |                                         |it can provide
   |                                         |audio-levels
   |Two way Opus Audio                       |
   |.........................................|
   |                                         |
   |Audio-levels per CSRCS is included in the|
   |RTP header                               |
   |                                         |



   +-----------------------------------+-------------------------------+
   | Offer SDP Contents                | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=- 20518 0 IN IP4 0.0.0.0        | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 54609 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109 0 8                           |                               |
   | c=IN IP4 24.23.204.141            | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264] - Alice can send    |
   |                                   | and recv audio                |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |



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   | a=rtpmap:0 PCMU/8000              | [RFC3551] PCMU Audio Codec    |
   | a=rtpmap:0 PCMA/8000              | [RFC3551] PCMA Audio Codec    |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:074c6550              | [RFC5245]                     |
   | a=ice-pwd:a28a397a4c3f31747d1ee34 | [RFC5245]                     |
   | 74af08a068                        |                               |
   | a=fingerprint:sha-256 19:E2:1C:3B | [RFC5245]                     |
   | :4B:9F:81:E6:B8:5C:F4:A5:A8:D8:73 |                               |
   | :04 :BB:05:2F:70:9F:04:A9:0E:05:E |                               |
   | 9:26:33:E8:70:88:A2               |                               |
   | a=setup:actpass                   | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp:54609 IN IP4 24.23.204.141 | [RFC3605]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=extmap:1/recvonly               | [RFC6465]                     |
   | urn:ietf:params:rtp-hdrext:csrc-  |                               |
   | audio-level                       |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [RFC6464]                     |
   | hdrext:ssrc-audio-level           |                               |
   | a=extmap:3 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP  2113667327   | [RFC5245]                     |
   | 192.168.1.4 61665 typ host        |                               |
   | a=candidate:1 1 UDP  694302207    | [RFC5245]                     |
   | 24.23.204.141 54609 typ srflx     |                               |
   | raddr 192.168.1.4 rport 61665     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                         Table 37: 5.4.2 SDP Offer


   +-----------------------------------+-------------------------------+
   | Answer SDP Contents               | RFC#/Notes                    |
   +-----------------------------------+-------------------------------+
   | v=0                               | [RFC4566]                     |
   | o=-  16833 0 IN IP4 0.0.0.0       | [RFC4566] - Session Origin    |
   |                                   | Information                   |
   | s=-                               | [RFC4566]                     |
   | t=0 0                             | [RFC4566]                     |
   | a=group:BUNDLE audio              | [I-D.ietf-mmusic-sdp-bundle-n |
   |                                   | egotiation]                   |
   | a=ice-options:trickle             | [I-D.ietf-mmusic-trickle-ice] |
   | ****** Audio m=line *********     | ***************************** |
   | m=audio 49203 UDP/TLS/RTP/SAVPF   | [RFC4566]                     |
   | 109 0 98                          |                               |



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   | c=IN IP4 98.248.92.77             | [RFC4566]                     |
   | a=mid:audio                       | [RFC5888]                     |
   | a=msid:ma ta                      | Identifies RTCMediaStream ID  |
   |                                   | (ma) and RTCMediaStreamTrack  |
   |                                   | ID (ta)                       |
   | a=sendrecv                        | [RFC3264]                     |
   | a=rtpmap:109 opus/48000/2         | [I-D.ietf-payload-rtp-opus]   |
   | a=rtpmap:0 PCMU/8000              | [RFC3551] PCMU Audio Codec    |
   | a=rtpmap:0 PCMA/8000              | [RFC3551] PCMA Audio Codec    |
   | a=maxptime:120                    | [RFC4566]                     |
   | a=ice-ufrag:c300d85b              | [RFC5245]                     |
   | a=ice-pwd:de4e99bd291c325921d5d47 | [RFC5245]                     |
   | efbabd9a2                         |                               |
   | a=fingerprint:sha-256 6B:8B:F0:65 | [RFC5245]                     |
   | :5F:78:E2:51:3B:AC:6F:F3:3F:46:1B |                               |
   | :35 :DC:B8:5F:64:1A:24:C2:43:F0:A |                               |
   | 1:58:D0:A1:2C:19:08               |                               |
   | a=setup:active                    | [RFC4145]                     |
   | a=dtls-id:1                       | [I-D.ietf-mmusic-dtls-sdp]    |
   | a=rtcp-mux                        | [RFC5761]                     |
   | a=rtcp-rsize                      | [RFC5506]                     |
   | a=rtcp-fb:* nack                  | [RFC5104]                     |
   | a=extmap:1/sendonly               | [RFC6465]                     |
   | urn:ietf:params:rtp-hdrext:csrc-  |                               |
   | audio-level                       |                               |
   | a=extmap:2 urn:ietf:params:rtp-   | [I-D.ietf-mmusic-sdp-bundle-n |
   | hdrext:sdes:mid                   | egotiation]                   |
   | a=candidate:0 1 UDP 2113667327    | [RFC5245]                     |
   | 192.168.1.7 51556 typ host        |                               |
   | a=candidate:1 1 UDP 1694302207    | [RFC5245]                     |
   | 98.248.92.77 49203 typ srflx      |                               |
   | raddr 192.168.1.7 rport 51556     |                               |
   | a=end-of-candidates               | [I-D.ietf-mmusic-trickle-ice] |
   +-----------------------------------+-------------------------------+

                        Table 38: 5.4.2 SDP Answer


5.4.3.  Successful legacy Interop Fallback with bundle-only

   In the scenario described below, Alice is a multi-stream capable
   WebRTC endpoint while Bob is a legacy VOIP end-point.  The SDP Offer/
   Answer exchange demonstrates successful session setup with fallback
   to audio only stream negotiated via bundle-only framework between the
   end-points.  Specifically,

   o  Offer from Alice describes 2 cameras via 2 video m=lines with both
      marked as bundle-only.



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   o  Since Bob doesnot recognize either the BUNDLE mechanism or the
      bundle-only attribute, he accepts only the audio stream from
      Alice.

   NOTE: Since Alice is unaware of Bob's support for BUNDLE framework,
   Alice ensures to include separate RTP/RTCP ports and candidate
   information.


         Successful 2-Way WebRTC <-> VOIP Interop

Alice                                                       Bob
|                                                           |
|                                                           |
|       Alice is a multistream capable WebRTC end-point     |
|          & Bob is behind a legacy VOIP system             |
|                                                           |
|Offer(Audio:Opus Video:2 VP8,2 H2.64 Streams) with         |
|          bundle-only                                      |
|---------------------------------------------------------->|
|     Alice marks both the video streams as bundle-only     |
|                                                           |
|                                                           |
|                  Answer(Audio:Opus)                       |
|<----------------------------------------------------------|
|                                                           |Bob
|                                                           |accepts
|                                                           |audio
|                                                           |stream,
|                                                           |since he
|                                                           |doesn't
|                                                           |recognize
|                                                           |bundle-only
|                                                           |
|                   Two way Opus Audio                      |
|...........................................................|
|                                                           |
|                                                           |


   +-------------------------------------+-----------------------------+
   | Offer SDP Contents                  | RFC#/Notes                  |
   +-------------------------------------+-----------------------------+
   | v=0                                 | [RFC4566]                   |
   | o=- 20519 0 IN IP4 0.0.0.0          | [RFC4566]                   |
   | s=-                                 | [RFC4566]                   |
   | t=0 0                               | [RFC4566]                   |
   | a=group:BUNDLE m0 m1 m2             | [I-D.ietf-mmusic-sdp-bundle |



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   |                                     | -negotiation] Alice         |
   |                                     | supports grouping of        |
   |                                     | m=lines under BUNDLE        |
   |                                     | semantics                   |
   | a=group:LS m0 m1                    | [RFC5888]                   |
   | a=ice-options:trickle               | [I-D.ietf-mmusic-trickle-ic |
   |                                     | e]                          |
   | ****** Audio m=line *********       | *************************** |
   |                                     | **                          |
   | m=audio 54609 UDP/TLS/RTP/SAVPF 109 | [RFC4566]                   |
   | c=IN IP4 24.23.204.141              | [RFC4566]                   |
   | a=mid:m0                            | [RFC5888] Audio m=line part |
   |                                     | of BUNDLE group with a      |
   |                                     | unique port number          |
   | a=msid:ma ta                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (ta) |
   | a=sendrecv                          | [RFC3264]                   |
   | a=rtpmap:109 opus/48000/2           | [I-D.ietf-payload-rtp-opus] |
   | a=rtcp-fb:109 nack                  | [RFC5104]                   |
   | a=maxptime:120                      | [RFC4566]                   |
   | a=ice-ufrag:074c6550                | [RFC5245]                   |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474 | [RFC5245]                   |
   | af08a068                            |                             |
   | a=fingerprint:sha-256 19:E2:1C:3B:4 | [RFC5245]                   |
   | B:9F:81:E6:B8:5C:F4:A5:A8:D8:73:04  |                             |
   | :BB:05:2F:70:9F:04:A9:0E:05:E9:26:3 |                             |
   | 3:E8:70:88:A2                       |                             |
   | a=setup:actpass                     | [RFC4145]                   |
   | a=dtls-id:1                         | [I-D.ietf-mmusic-dtls-sdp]  |
   | a=rtcp-mux                          | [RFC5761]                   |
   | a=rtcp:64678 IN IP4 24.23.204.141   | [RFC3605]                   |
   | a=rtcp-rsize                        | [RFC5506]                   |
   | a=extmap:1 urn:ietf:params:rtp-     | [RFC6464]                   |
   | hdrext:ssrc-audio-level             |                             |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | a=candidate:0 1 UDP  2113667327     | [RFC5245]                   |
   | 192.168.1.4 61665 typ host          |                             |
   | a=candidate:1 1 UDP  694302207      | [RFC5245]                   |
   | 24.23.204.141 54609 typ srflx raddr |                             |
   | 192.168.1.4 rport 61665             |                             |
   | a=candidate:0 1 UDP 2113667326      | [RFC5245]                   |
   | 192.168.1.4 61667 typ host          |                             |
   | a=candidate:1 1 UDP  1694302206     | [RFC5245]                   |
   | 24.23.204.141 64678 typ srflx raddr |                             |
   | 192.168.1.4 rport 61667             |                             |
   | ****** Video-1 m=line *********     | *************************** |



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   |                                     | **                          |
   | m=video 0 UDP/TLS/RTP/SAVPF 98 100  | bundle-only video line with |
   |                                     | port number set to zero     |
   | c=IN IP4 24.23.204.141              | [RFC4566]                   |
   | a=bundle-only                       | [I-D.ietf-mmusic-sdp-bundle |
   |                                     | -negotiation]               |
   | a=mid:m1                            | [RFC5888] Video m=line part |
   |                                     | of BUNDLE group             |
   | a=msid:ma tb                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (tb) |
   | a=sendrecv                          | [RFC3264]                   |
   | a=rtpmap:98 VP8/90000               | [I-D.ietf-payload-vp8]      |
   | a=imageattr:98 [x=1280,y=720]       | [RFC6236]                   |
   | a=fmtp:98 max-fr=30                 | [RFC4566]                   |
   | a=rtcp-fb:* nack                    | [RFC5104]                   |
   | a=rtcp-fb:* nack pli                | [RFC5104]                   |
   | a=rtcp-fb:* ccm fir                 | [RFC5104]                   |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   | ****** Video-2 m=line *********     | *************************** |
   |                                     | **                          |
   | m=video 0 UDP/TLS/RTP/SAVPF 101 103 | bundle-only video line with |
   |                                     | port number set to zero     |
   | c=IN IP4 24.23.204.141              | [RFC4566]                   |
   | a=bundle-only                       | [I-D.ietf-mmusic-sdp-bundle |
   |                                     | -negotiation]               |
   | a=mid:m2                            | [RFC5888] Video m=line part |
   |                                     | of BUNDLE group             |
   | a=msid:ma tc                        | Identifies RTCMediaStream   |
   |                                     | ID (ma) and                 |
   |                                     | RTCMediaStreamTrack ID (tc) |
   | a=sendrecv                          | [RFC3264]                   |
   | a=rtpmap:101 H264/90000             | [RFC3984]                   |
   | a=rtpmap:103 H264/90000             | [RFC3984]                   |
   | a=fmtp:101 profile-level-id=4d0028  | [RFC3984]Camera-2,Encoding- |
   | ;packetization-mode=1;max-fr=30     | 1 Resolution                |
   | a=rtcp-fb:* nack                    | [RFC5104]                   |
   | a=rtcp-fb:* nack pli                | [RFC5104]                   |
   | a=rtcp-fb:* ccm fir                 | [RFC5104]                   |
   | a=extmap:2 urn:ietf:params:rtp-     | [I-D.ietf-mmusic-sdp-bundle |
   | hdrext:sdes:mid                     | -negotiation]               |
   +-------------------------------------+-----------------------------+

                 Table 39: 5.4.3 SDP Simulcast bundle-only


   +----------------------------------------+--------------------------+



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   | Answer SDP Contents                    | RFC#/Notes               |
   +----------------------------------------+--------------------------+
   | v=0                                    | [RFC4566]                |
   | o=- 20519 0 IN IP4 0.0.0.0             | [RFC4566]                |
   | s=-                                    | [RFC4566]                |
   | t=0 0                                  | [RFC4566]                |
   | ****** Audio m=line *********          | ************************ |
   |                                        | *****                    |
   | m=audio 49203 UDP/TLS/RTP/SAVPF 109    | [RFC4566]                |
   | c=IN IP4 24.23.204.141                 | [RFC4566]                |
   | a=rtcp:60065 IN IP4 24.23.204.141      | [RFC3605]                |
   | a=sendrecv                             | [RFC3264]                |
   | a=rtpmap:109 opus/48000/2              | [I-D.ietf-payload-rtp-op |
   |                                        | us]                      |
   | a=maxptime:120                         | [RFC4566]                |
   | a=ice-ufrag:ufrag:c300d85b             | [RFC5245]                |
   | a=ice-                                 | [RFC5245]                |
   | pwd:de4e99bd291c325921d5d47efbabd9a2   |                          |
   | a=fingerprint:sha-256 6B:8B:F0:65:5F:7 | [RFC5245]                |
   | 8:E2:51:3B:AC:6F:F3:3F:46:1B:35 :DC:B8 |                          |
   | :5F:64:1A:24:C2:43:F0:A1:58:D0:A1:2C:1 |                          |
   | 9:08                                   |                          |
   | a=setup:active                         | [RFC4145]                |
   | a=rtcp-rsize                           | [RFC5506]                |
   | a=rtcp-fb:109 nack                     | [RFC5104]                |
   | a=extmap:1 urn:ietf:params:rtp-hdrext  | [RFC6464]                |
   | :ssrc-audio-level                      |                          |
   | a=candidate:0 1 UDP  2113667327        | [RFC5245]                |
   | 192.168.1.7 51556 typ host             |                          |
   | a=candidate:1 1 UDP  694302207         | [RFC5245]                |
   | 98.248.92.77 49203 typ srflx raddr     |                          |
   | 192.168.1.7 rport 51556                |                          |
   | a=candidate:0 2 UDP 2113667326         | [RFC5245]                |
   | 192.168.1.7 51558 typ host             |                          |
   | a=candidate:1 2 UDP  1694302206        | [RFC5245]                |
   | 98.248.92.77 60065 typ srflx raddr     |                          |
   | 192.168.1.7 rport 51558                |                          |
   | ****** Video m=line *********          | ************************ |
   |                                        | *****                    |
   | m=video 0 UDP/TLS/RTP/SAVPF 98 100     | Bob doesn't recognize    |
   |                                        | bundle-only and hence    |
   |                                        | the m=line is rejected   |
   |                                        | implicitly due to port 0 |
   | ****** Video m=line *********          | ************************ |
   |                                        | *****                    |
   | m=video 0 UDP/TLS/RTP/SAVPF 98 100     | Bob doesn't recognize    |
   |                                        | bundle-only and hence    |
   |                                        | the m=line is rejected   |



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   |                                        | implicitly due to port 0 |
   +----------------------------------------+--------------------------+

                        Table 40: 5.4.3 SDP Answer


5.4.4.  Legacy Interop with RTP/AVP profile

   In the scenario desribed below, Alice is a legacy end-point which
   sends [RFC3264] Offer with RTP/AVP based audio and video descriptions
   along with DTLS fingerprint and RTCP feedback information.

   On the other hand, Bob being a WebRTC end-point follows the
   procedures in section 5.1.2 of [I-D.ietf-rtcweb-jsep] and accepts the
   Alice's offer for DTLS-SRTP based session with RTCP feedback.


           Successful 2-Way WebRTC <-> VOIP Interop

Alice                                                          Bob
|                                                               |
|                                                               |
|  Alice is a legacy VOIP End-point & Bob is a WebRTC End-Point |
|                                                               |
|                                                               |
|                                                               |
|              Offer(Audio:Opus Video:H.264)                    |
|-------------------------------------------------------------->|
|                                                               |
|                                                               |
|Alice includes :                                               |
|Legacy compliant media description (RTP/AVP) with dtls         |
|fingerprint and rtcp feedback support                          |
|                                                               |
|             Answer(Audio:Opus, Video:H.264)                   |
|<--------------------------------------------------------------|
|                                                               |Bob
|                                                               |accepts
|                                                               |"legacy
|                                                               |compliant"
|                                                               |m=line
|                                                               |
|                                                               |
|             Two way Opus Audio, H.264 Video                   |
|...............................................................|
|       Session also suports RTP/RTCP Mux, RTCP Feedback        |
|                                                               |




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   +----------------------------------------+--------------------------+
   | Offer SDP Contents                     | RFC#/Notes               |
   +----------------------------------------+--------------------------+
   | v=0                                    | [RFC4566]                |
   | o=- 20518 0 IN IP4 0.0.0.0             | [RFC4566]                |
   | s=-                                    | [RFC4566]                |
   | t=0 0                                  | [RFC4566]                |
   | a=ice-ufrag:074c6550                   | [RFC5245]                |
   | a=ice-                                 | [RFC5245]                |
   | pwd:a28a397a4c3f31747d1ee3474af08a068  |                          |
   | a=rtcp-rsize                           | [RFC5506]                |
   | ****** Audio m=line *********          | ************************ |
   |                                        | *****                    |
   | m=audio 54732 RTP/AVP 109              | [RFC4566]Alice includes  |
   |                                        | RTP/AVP audio stream     |
   |                                        | description              |
   | c=IN IP4 24.23.204.141                 | [RFC4566]                |
   | a=fingerprint:sha-256 19:E2:1C:3B:4B:9 | [RFC5245]                |
   | F:81:E6:B8:5C:F4:A5:A8:D8:73:04 :BB:05 |                          |
   | :2F:70:9F:04:A9:0E:05:E9:26:33:E8:70:8 |                          |
   | 8:A2                                   |                          |
   | a=rtpmap:109 opus/48000                |                          |
   | a=ptime:20                             |                          |
   | a=sendrecv                             | [RFC3264]                |
   | a=rtcp-mux                             | [RFC5761]Alice still     |
   |                                        | includes RTP/RTCP Mux    |
   |                                        | support                  |
   | a=candidate:0 1 UDP  2113667327        | [RFC5245]                |
   | 192.168.1.4 54732 typ host             |                          |
   | a=candidate:1 1 UDP  694302207         | [RFC5245]                |
   | 24.23.204.141 54732 typ srflx raddr    |                          |
   | 192.168.1.4 rport 54732                |                          |
   | a=candidate:0 2 UDP 2113667326         | [RFC5245]                |
   | 192.168.1.4 64678 typ host             |                          |
   | a=candidate:1 2 UDP  1694302206        | [RFC5245]                |
   | 24.23.204.141 64678 typ srflx raddr    |                          |
   | 192.168.1.4 rport 64678                |                          |
   | a=rtcp-fb:109 nack                     | [RFC5104]She adds her    |
   |                                        | intent for NACK RTCP     |
   |                                        | feedback support         |
   | ****** Video m=line *********          | ************************ |
   |                                        | *****                    |
   | m=video 62445 RTP/AVP 120              | [RFC4566]Alice includes  |
   |                                        | RTP/AVP video stream     |
   |                                        | description              |
   | c=IN IP4 24.23.204.141                 | [RFC4566]                |
   | a=fingerprint:sha-256 DC:B8:5F:64:1A:2 | [RFC5245]                |
   | 4:C2:43:F0:A1:58:D0:A1:2C:19:08 :6B:8B |                          |



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   | :F0:65:5F:78:E2:51:3B:AC:6F:F3:3F:46:1 |                          |
   | B:35                                   |                          |
   | a=rtpmap:120 VP8/90000                 | [I-D.ietf-payload-vp8]   |
   | a=sendrecv                             | [RFC3264]                |
   | a=rtcp-mux                             | [RFC5761]Alice intends   |
   |                                        | to perform RTP/RTCP Mux  |
   | a=candidate:0 1 UDP  2113667327        | [RFC5245]                |
   | 192.168.1.4 62445 typ host             |                          |
   | a=candidate:1 1 UDP  1694302207        | [RFC5245]                |
   | 24.23.204.141 62537 typ srflx raddr    |                          |
   | 192.168.1.4 rport 62445                |                          |
   | a=candidate:0 2 2113667326 192.168.1.4 | [RFC5245]                |
   | 54721 typ host                         |                          |
   | a=candidate:1 2 UDP 1694302206         | [RFC5245]                |
   | 24.23.204.141 54721 typ srflx raddr    |                          |
   | 192.168.1.4 rport 54721                |                          |
   | a=rtcp-fb:120 nack pli                 | [RFC5104] Alice          |
   |                                        | indicates support for    |
   |                                        | Picture loss Indication  |
   |                                        | and NACK RTCP feedback   |
   | a=rtcp-fb:120 ccm fir                  | [RFC5104]                |
   +----------------------------------------+--------------------------+

                         Table 41: 5.4.5 SDP Offer


   +----------------------------------------+--------------------------+
   | Answer SDP Contents                    | RFC#/Notes               |
   +----------------------------------------+--------------------------+
   | v=0                                    | [RFC4566]                |
   | o=-  16833 0 IN IP4 0.0.0.0            | [RFC4566]                |
   | s=-                                    | [RFC4566]                |
   | t=0 0                                  | [RFC4566]                |
   | ****** Audio m=line *********          | ************************ |
   |                                        | *****                    |
   | m=audio 49203 RTP/AVP 109              | [RFC4566] Bob accepts    |
   |                                        | RTP/AVP based audio      |
   |                                        | stream                   |
   | c=IN IP4 98.248.92.77                  | [RFC4566]                |
   | a=rtpmap:109 opus/48000                |                          |
   | a=ptime:20                             |                          |
   | a=sendrecv                             | [RFC3264]                |
   | a=ice-ufrag:c300d85b                   | [RFC5245]                |
   | a=ice-                                 | [RFC5245]                |
   | pwd:de4e99bd291c325921d5d47efbabd9a2   |                          |
   | a=fingerprint:sha-256 BB:05:2F:70:9F:0 | [RFC5245]                |
   | 4:A9:0E:05:E9:26:33:E8:70:88:A2 :19:E2 |                          |
   | :1C:3B:4B:9F:81:E6:B8:5C:F4:A5:A8:D8:7 |                          |



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   | 3:04                                   |                          |
   | a=rtcp-mux                             | [RFC5761]                |
   | a=candidate:0 1 UDP 2113667327         | [RFC5245]                |
   | 192.168.1.7 49203 typ host             |                          |
   | a=candidate:1 1 UDP 1694302207         | [RFC5245]                |
   | 98.248.92.77 49203 typ srflx raddr     |                          |
   | 192.168.1.7 rport 49203                |                          |
   | a=candidate:0 2 UDP 2113667326         | [RFC5245]                |
   | 192.168.1.7 60065 typ host             |                          |
   | a=candidate:1 2 UDP 1694302206         | [RFC5245]                |
   | 98.248.92.77 60065 typ srflx raddr     |                          |
   | 192.168.1.7 rport 60065                |                          |
   | a=rtcp-fb:109 nack                     | [RFC5104]                |
   | ****** Video m=line *********          | ************************ |
   |                                        | *****                    |
   | m=video  63130 RTP/SAVP 120            | [RFC4566] Bob accepts    |
   |                                        | RTP/AVP based video      |
   |                                        | stram                    |
   | c=IN IP4 98.248.92.77                  | [RFC4566]                |
   | a=rtpmap:120 VP8/90000                 | [I-D.ietf-payload-vp8]   |
   | a=sendrecv                             | [RFC3264]                |
   | a=ice-ufrag:e39091na                   | [RFC5245]                |
   | a=ice-                                 | [RFC5245]                |
   | pwd:dbc325921d5dd29e4e99147efbabd9a2   |                          |
   | a=fingerprint:sha-256 BB:0A9:0E:05:E9: | [RFC5245]                |
   | 26:33:E8:70:88:A25:2F:70:9F:04: :19:E2 |                          |
   | :1C:3B:4B:9F:81:5:2F:70:9F:04::F4:A5:A |                          |
   | 8:D8:                                  |                          |
   | a=rtcp-mux                             | [RFC5761]                |
   | a=candidate:0 1 UDP 2113667327         | [RFC5245]                |
   | 192.168.1.7 63130 typ host             |                          |
   | a=candidate:1 1 UDP 1694302207         | [RFC5245]                |
   | 98.248.92.77 63130 typ srflx raddr     |                          |
   | 192.168.1.7 rport 63130                |                          |
   | a=candidate:0 2 UDP 2113667326         | [RFC5245]                |
   | 192.168.1.7 56607 typ host             |                          |
   | a=candidate:1 2 UDP 1694302206         | [RFC5245]                |
   | 98.248.92.77 56607 typ srflx raddr     |                          |
   | 192.168.1.7 rport 56607                |                          |
   | a=rtcp-fb:120 nack pli                 | [RFC5104]                |
   | a=rtcp-fb:120 ccm fir                  | [RFC5104]                |
   +----------------------------------------+--------------------------+

                        Table 42: 5.4.5 SDP Answer







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6.  IANA Considerations

   This document requires no actions from IANA.

7.  Acknowledgments

   We would like to thank Justin Uberti, Chris Flo, Paul Kyzivat for
   their detailed review and inputs.

8.  Change Log

   [RFC EDITOR NOTE: Please remove this section when publishing]

   Changes from draft-ietf-rtcweb-sdp-02 to draft-ietf-rtcweb-sdp-04

   o  Alignment with JSEP-19.

   o  Added a=identity example.

   o  Added a=dtls-id, a=group:LS in the examples.

   o  Added Appendix section to capture list of checklists for the
      attributes.

   o  Removed SSRC lines to match JSEP-19.

   o  Closed open issues on a=fingerprint, a=rtcp and a=rtcp-mux-only
      from ietf96 to reflect JSEP-19.

   o  Simplied Inter-op example

   Changes from draft-ietf-rtcweb-sdp-02

   o  Version increment to avoid expiry

   Changes from draft-ietf-rtcweb-sdp-01

   o  Complete face-lift

   o  Added visual markers around m=lines to indicate their type, added
      spacing between tables for aiding readers

   o  Updated table names to indicate offer vs answer

   o  Attempted to align to latest versions of SCTP, BUNDLE, MSID drafts

   o  Added mid header extensions to all the lines




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   o  Harmonized BUNDLE semantics and conventions updated.

   Changes from draft-ietf-rtcweb-sdp-00

   o  Updated Simulcast/FEC/RTX examples to use RID framework

   o  Fixed BUNDLE references for a=bundle-only

   Changes from draft-nandakumar-rtcweb-sdp-08

   o  Fixed typos

   o  Moved to a WG version

   Changes from draft-nandakumar-rtcweb-sdp-06 and draft-nandakumar-
   rtcweb-sdp-07

   o  Added clarification on Call-Flow diagram usage

   o  More cleanups

   Changes from draft-nandakumar-rtcweb-sdp-05

   o  Added Ascii chart for all the SDP Eaxamples

   o  Improved text and updated SDP Examples for Simulcast and FEC

   o  Fixed MediaStream ID Semantics SDP Errors

   Changes from draft-nandakumar-rtcweb-sdp-04

   o  Interim version of the draft to avert expiry

   o  Corrected placement of c= line as per RFC4566

   o  Updated simulcast SDP to reflect draft-westerlund-avtcore-rtp-
      simulcast-04

   Changes from draft-nandakumar-rtcweb-sdp-03

   o  Aligned more closely with JSEP version -05

   o  Added Conventions to help readability

   o  Add more examples to clarify BUNDLE use-cases

   Changes from draft-nandakumar-rtcweb-sdp-02




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   o  Major refactoring was done to group the examples in to categories

   o  SDP was updated through out to reflect JSEP-04 style of defining
      attributes per m=line than at the session level.

   o  Added 8 new examples.

   o  Updated references for Trickle, Unified Plan

   o  Add section to explain the syntax conventions followed in the
      examples.

   Changes from draft-nandakumar-rtcweb-sdp-01

   o  Updated references to OPUS RTP Payload Specification.

   o  Updated BUNDLE examples based on the latest draft-ietf-mmusic-sdp-
      bundle-negotiation.

   o  Added examples for multiple audio and video flows based on Unified
      Plan.

   o  Added new examples for RTX and FEC streams

   o  Updated Simulcast and SVC examples

   Changes from draft-nandakumar-rtcweb-sdp-00

   o  Fixed editorial comments on the mailing list.

   o  Updated Data-channel SDP information based on draft-ietf-mmusic-
      sctp-sdp.

   o  Updated BUNDLE examples based on draft-ietf-mmusic-sdp-bundle-
      negotiation.

   o  Added examples for few more BUNDLE variants

   o  Added new examples for Simulcast and SVC

9.  Informative References

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264, DOI
              10.17487/RFC3264, June 2002,
              <http://www.rfc-editor.org/info/rfc3264>.





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   [RFC4145]  Yon, D. and G. Camarillo, "TCP-Based Media Transport in
              the Session Description Protocol (SDP)", RFC 4145, DOI
              10.17487/RFC4145, September 2005,
              <http://www.rfc-editor.org/info/rfc4145>.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
              July 2006, <http://www.rfc-editor.org/info/rfc4566>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
              RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245, DOI
              10.17487/RFC5245, April 2010,
              <http://www.rfc-editor.org/info/rfc5245>.

   [RFC5506]  Johansson, I. and M. Westerlund, "Support for Reduced-Size
              Real-Time Transport Control Protocol (RTCP): Opportunities
              and Consequences", RFC 5506, DOI 10.17487/RFC5506, April
              2009, <http://www.rfc-editor.org/info/rfc5506>.

   [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
              Video Conferences with Minimal Control", STD 65, RFC 3551,
              DOI 10.17487/RFC3551, July 2003,
              <http://www.rfc-editor.org/info/rfc3551>.

   [RFC3952]  Duric, A. and S. Andersen, "Real-time Transport Protocol
              (RTP) Payload Format for internet Low Bit Rate Codec
              (iLBC) Speech", RFC 3952, DOI 10.17487/RFC3952, December
              2004, <http://www.rfc-editor.org/info/rfc3952>.

   [RFC4796]  Hautakorpi, J. and G. Camarillo, "The Session Description
              Protocol (SDP) Content Attribute", RFC 4796, DOI 10.17487/
              RFC4796, February 2007,
              <http://www.rfc-editor.org/info/rfc4796>.

   [RFC5761]  Perkins, C. and M. Westerlund, "Multiplexing RTP Data and
              Control Packets on a Single Port", RFC 5761, DOI 10.17487/
              RFC5761, April 2010,
              <http://www.rfc-editor.org/info/rfc5761>.







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   [RFC3556]  Casner, S., "Session Description Protocol (SDP) Bandwidth
              Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC
              3556, DOI 10.17487/RFC3556, July 2003,
              <http://www.rfc-editor.org/info/rfc3556>.

   [RFC5104]  Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
              "Codec Control Messages in the RTP Audio-Visual Profile
              with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
              February 2008, <http://www.rfc-editor.org/info/rfc5104>.

   [RFC4588]  Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
              Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
              DOI 10.17487/RFC4588, July 2006,
              <http://www.rfc-editor.org/info/rfc4588>.

   [RFC5956]  Begen, A., "Forward Error Correction Grouping Semantics in
              the Session Description Protocol", RFC 5956, DOI 10.17487/
              RFC5956, September 2010,
              <http://www.rfc-editor.org/info/rfc5956>.

   [RFC5888]  Camarillo, G. and H. Schulzrinne, "The Session Description
              Protocol (SDP) Grouping Framework", RFC 5888, DOI
              10.17487/RFC5888, June 2010,
              <http://www.rfc-editor.org/info/rfc5888>.

   [RFC6236]  Johansson, I. and K. Jung, "Negotiation of Generic Image
              Attributes in the Session Description Protocol (SDP)", RFC
              6236, DOI 10.17487/RFC6236, May 2011,
              <http://www.rfc-editor.org/info/rfc6236>.

   [RFC3984]  Wenger, S., Hannuksela, M., Stockhammer, T., Westerlund,
              M., and D. Singer, "RTP Payload Format for H.264 Video",
              RFC 3984, DOI 10.17487/RFC3984, February 2005,
              <http://www.rfc-editor.org/info/rfc3984>.

   [RFC5583]  Schierl, T. and S. Wenger, "Signaling Media Decoding
              Dependency in the Session Description Protocol (SDP)", RFC
              5583, DOI 10.17487/RFC5583, July 2009,
              <http://www.rfc-editor.org/info/rfc5583>.

   [RFC5576]  Lennox, J., Ott, J., and T. Schierl, "Source-Specific
              Media Attributes in the Session Description Protocol
              (SDP)", RFC 5576, DOI 10.17487/RFC5576, June 2009,
              <http://www.rfc-editor.org/info/rfc5576>.







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   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.
              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
              July 2003, <http://www.rfc-editor.org/info/rfc3550>.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              DOI 10.17487/RFC3261, June 2002,
              <http://www.rfc-editor.org/info/rfc3261>.

   [RFC2326]  Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time
              Streaming Protocol (RTSP)", RFC 2326, DOI 10.17487/
              RFC2326, April 1998,
              <http://www.rfc-editor.org/info/rfc2326>.

   [RFC3605]  Huitema, C., "Real Time Control Protocol (RTCP) attribute
              in Session Description Protocol (SDP)", RFC 3605, DOI
              10.17487/RFC3605, October 2003,
              <http://www.rfc-editor.org/info/rfc3605>.

   [RFC2833]  Schulzrinne, H. and S. Petrack, "RTP Payload for DTMF
              Digits, Telephony Tones and Telephony Signals", RFC 2833,
              DOI 10.17487/RFC2833, May 2000,
              <http://www.rfc-editor.org/info/rfc2833>.

   [RFC6464]  Lennox, J., Ed., Ivov, E., and E. Marocco, "A Real-time
              Transport Protocol (RTP) Header Extension for Client-to-
              Mixer Audio Level Indication", RFC 6464, DOI 10.17487/
              RFC6464, December 2011,
              <http://www.rfc-editor.org/info/rfc6464>.

   [RFC6465]  Ivov, E., Ed., Marocco, E., Ed., and J. Lennox, "A Real-
              time Transport Protocol (RTP) Header Extension for Mixer-
              to-Client Audio Level Indication", RFC 6465, DOI 10.17487/
              RFC6465, December 2011,
              <http://www.rfc-editor.org/info/rfc6465>.

   [RFC7022]  Begen, A., Perkins, C., Wing, D., and E. Rescorla,
              "Guidelines for Choosing RTP Control Protocol (RTCP)
              Canonical Names (CNAMEs)", RFC 7022, DOI 10.17487/RFC7022,
              September 2013, <http://www.rfc-editor.org/info/rfc7022>.

   [I-D.ietf-mmusic-sdp-bundle-negotiation]
              Holmberg, C., Alvestrand, H., and C. Jennings,
              "Negotiating Media Multiplexing Using the Session
              Description Protocol (SDP)", draft-ietf-mmusic-sdp-bundle-
              negotiation-24 (work in progress), January 2016.



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   [I-D.ietf-mmusic-sdp-simulcast]
              Burman, B., Westerlund, M., Nandakumar, S., and M. Zanaty,
              "Using Simulcast in SDP and RTP Sessions", draft-ietf-
              mmusic-sdp-simulcast-03 (work in progress), October 2015.

   [I-D.ietf-mmusic-rid]
              Thatcher, P., Zanaty, M., Nandakumar, S., Burman, B.,
              Roach, A., and B. Campen, "RTP Payload Format
              Constraints", draft-ietf-mmusic-rid-04 (work in progress),
              February 2016.

   [I-D.ietf-payload-rtp-opus]
              Spittka, J., Vos, K., and J. Valin, "RTP Payload Format
              for the Opus Speech and Audio Codec", draft-ietf-payload-
              rtp-opus-11 (work in progress), April 2015.

   [I-D.ietf-payload-vp8]
              Westin, P., Lundin, H., Glover, M., Uberti, J., and F.
              Galligan, "RTP Payload Format for VP8 Video", draft-ietf-
              payload-vp8-17 (work in progress), September 2015.

   [I-D.ietf-rtcweb-jsep]
              Uberti, J., Jennings, C., and E. Rescorla, "Javascript
              Session Establishment Protocol", draft-ietf-rtcweb-jsep-12
              (work in progress), October 2015.

   [I-D.ietf-mmusic-trickle-ice]
              Ivov, E., Rescorla, E., and J. Uberti, "Trickle ICE:
              Incremental Provisioning of Candidates for the Interactive
              Connectivity Establishment (ICE) Protocol", draft-ietf-
              mmusic-trickle-ice-02 (work in progress), January 2015.

   [I-D.ietf-mmusic-msid]
              Alvestrand, H., "WebRTC MediaStream Identification in the
              Session Description Protocol", draft-ietf-mmusic-msid-11
              (work in progress), October 2015.

   [I-D.ietf-mmusic-sctp-sdp]
              Holmberg, C., Loreto, S., and G. Camarillo, "Stream
              Control Transmission Protocol (SCTP)-Based Media Transport
              in the Session Description Protocol (SDP)", draft-ietf-
              mmusic-sctp-sdp-15 (work in progress), September 2015.

   [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.




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   [I-D.ietf-payload-flexible-fec-scheme]
              Singh, V., Begen, A., Zanaty, M., and G. Mandyam, "RTP
              Payload Format for Flexible Forward Error Correction
              (FEC)", draft-ietf-payload-flexible-fec-scheme-01 (work in
              progress), October 2015.

   [I-D.ietf-mmusic-mux-exclusive]
              Holmberg, C., "Indicating Exclusive Support of RTP/RTCP
              Multiplexing using SDP", draft-ietf-mmusic-mux-
              exclusive-08 (work in progress), June 2016.

   [I-D.ietf-mmusic-dtls-sdp]
              Holmberg, C. and R. Shpount, "Using the SDP Offer/Answer
              Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-22 (work
              in progress), March 2017.

   [I-D.ietf-rtcweb-security-arch]
              Rescorla, E., "WebRTC Security Architecture", draft-ietf-
              rtcweb-security-arch-11 (work in progress), March 2015.

   [WebRTC]   W3C, "WebRTC 1.0: Real-time Communication Between
              Browsers",
              <http://dev.w3.org/2011/webrtc/editor/webrtc.html> , .

Appendix A.  Appendix

A.1.  JSEP SDP Attributes Checklist

   This section compiles a high-level checklist of required SDP
   attributes to be verified against the examples defined in this
   specification.  The goal here is to ensure that the examples are
   compliant to the rules defined in section 5 of the
   [I-D.ietf-rtcweb-jsep] specification.

A.1.1.  Common Checklist

   This subsection lists SDP attributes that mostly apply at the session
   level.

   o  v=0 MUST be the first SDP line

   o  o= line MUST follow with values '-' for username, 64 bit value for
      session id and dummy values for 'nettype', 'addrtype' and
      'unicast-address' (such as IN IP4 0.0.0.0)

   o  o= line MUST have the session version incremented in the cases of
      subsequent offers.




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   o  s= MUST be the third line with value '-'.

   o  t= line MUST follow with values for 'start-time' and 'stop-time'
      set to zeroes.

   o  a=identity line MUST be included at the session level if WEBRTC
      Identity is being used.

   o  a=ice-options:trickle MUST be present at the session level in all
      offers and answers when supported.

A.1.2.  RTP Media Description Checklist

   Following set of checklist items apply to RTP audio and video media
   descriptions.

   o  The media description's port value MUST either be set to dummy
      value of '9' or MUST use the port from the default candidate, if
      available.

   o  The media description's proto value MUST be 'UDP/TLS/RTP/SAVPF'
      for JSEP offers.

   o  JSEP answerer MUST support any combination of RTP/[S]AVP[F] for
      interoperability scenarios as defined in section 5 of
      [I-D.ietf-rtcweb-jsep]

   o  c= line MUST be the first line in a media description.  A dummy
      value of 'IN IP 0.0.0.0' is set if there are no candidates
      gathered or its value MUST match the default candidate.

   o  a=mid attribute MUST be in included.

   o  One of a=sendrecv/a=sendonly/a=recvonly/a=inactive SDP direction
      attributes MUST be present.

   o  a=rtpmap and a=fmtp attributes per primary, retransmission and
      forward error correction media format MUST be included.

   o  a=rtcp-fb lines for each supported feedback mechanism MUST be
      included when using RTP with feedback

   o  a=imageattr can be optionally present for video media
      descriptions.

   o  a=msid line MUST be included for all the media senders identifying
      the MediaStreamTrack (i.e when a=sendonly/a=sendrecv attribute is
      present).



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   o  a=extmap line identifying the BUNDLE header extension MUST be
      present.

   o  a=extmap lines for other supported RTP header extensions MUST be
      included.

   o  a=rid line 'per encoding' with the direction of 'send' MUST be
      included when further constraining the media format or multiple
      encodings per media format is needed.

   o  a=simulcast line MUST be present if there exists more than one
      'a=rid' lines for the media senders.

   o  a=bundle-only attribute MUST be present for media descriptions
      that are impacted by various bundle policies (such as max-bundle/
      balanced)

   o  For media descriptions that aren't "a=bundle-only" and that have
      unique address, following attributes MUST be present:

      *  a=ice-ufrag and a=ice-pwd

      *  a=fingerprint

      *  a=setup with value 'actpass' in the offers and a value of
         'active'/'passive' in the answerer.

      *  a=dtls-id

      *  a=rtcp

      *  a=rtcp-mux

      *  For offerers requiring RTCP to be multiplexed, 'a=rtcp-mux-
         only' line

      *  a=rtcp-rsize

   o  a=group:BUNDLE line with all the 'mid' identifiers part of BUNDLE
      is included at the session level.

   o  a=group:LS session level attribute MUST be included wth 'mid'
      identifiers that are part of the lip same sync group.








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A.1.3.  DataChannel Media Description checklist

   If a datachannel is required, an 'application' type media description
   MUST be included with the following properties:

   o  Media description's proto value MUST be 'UDP/DTLS/SCTP' in the
      JSEP offers.

   o  An JSEP answerer MUST support reception of
      'UDP/DTLS/SCTP'/'TCP/DTLS/SCTP'/'DTLS/SCTP' for backward
      compatibility reasons.

   o  A value of 'webrtc-datachannel' MUST be used for the media
      description 'fmt' value.

   o  a=mid line MUST be present.

   o  a=sctp-port with SCTP port number MUST be included.

   o  a=max-message-size MAY be included, if appropriate.

Authors' Addresses

   Suhas Nandakumar
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Email: snandaku@cisco.com


   Cullen Jennings
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Phone: +1 408 421-9990
   Email: fluffy@cisco.com











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