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Versions: 00 01 02 03 04 05 06 07 08 draft-ietf-rtcweb-sdp

Network Working Group                                      S. Nandakumar
Internet-Draft                                               C. Jennings
Intended status:  Informational                                    Cisco
Expires:  April 18, 2013                                October 15, 2012


                           SDP for the WebRTC
                     draft-nandakumar-rtcweb-sdp-00

Abstract

   The Web Real-Time Communication (WebRTC) [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 negotiataion happens based on the SDP Offer/Answer
   exchange mechanism described in the RFC 3264 [RFC3264].

   This document serves a introductory purpose in describing the role of
   SDP for the most common WebRTC use-cases.

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 April 18, 2013.

Copyright Notice

   Copyright (c) 2012 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



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   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  . . . . . . . . . . . . . . . . .  4
   5.  WebRTC Session Description Examples  . . . . . . . . . . . . .  5
     5.1.  Secure Two-Way Audio,Video and Data with RTCP Feedback . .  5
     5.2.  Secure Two-way Audio,Video,Data and remove data stream . . 11
     5.3.  Secure Two-Way Audio,Video w/Bundle  . . . . . . . . . . . 15
     5.4.  Successful One Way Session with 2 Video Streams  . . . . . 19
     5.5.  Add New Media (video)  . . . . . . . . . . . . . . . . . . 23
   6.  WebRTC <-> Legacy Interop Examples . . . . . . . . . . . . . . 28
     6.1.  Secure Two-Way Audio,Video w/Feedback - WebRTC <->
           Legacy Interop . . . . . . . . . . . . . . . . . . . . . . 28
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 33
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 33
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 33
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 33
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 34
























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1.  Introduction

   Javascript Session Exchange Protocol(JSEP) [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
   multimedia session.  For this purpose, SDP is used to construct
   [RFC3264] offers/answers for describing (media and non-media) streams
   as appropriate for recipients of a session description to participate
   in the session.

   The remainder of this document is organized as follows:  Section 3
   and 4 provide an overview of SDP and the Offer/Answer exchange
   mechanism.  Section 5 and 6 provide sample SDP usages 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 the [RFC4566].

   The Session Description Protocol (SDP) [RFC4566] describes multimedia
   sessions,which can be audio,video, whiteboards,fax,modem, and other
   streams.  It 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.

   As of today SDP is widely used in the context of Session Initiation
   Protocol,Real-time Transport Protocol, and Real-time Streaming
   Protocol.

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

   [WEBRTC] proposes JavaScript application to fully control the
   signaling plane of a multimedia session as described in the JSEP



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   specification [JSEP].  JSEP provides mechanisms to create session
   characterisation and media definition information to conduct the
   session based on SDP exchanges.

   In this context,SDP serves two purposes:
      Provide grammatical structure syntatically
      Semantically convey partipant's intention and capabilities.


4.  Offer/Answer and the WebRTC

   This section introduces SDP Offer/Answer Exchange mechanism mandated
   by WebRTC for negotitating 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 [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 modelled on 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 initial setup stages as well as for eventual
   session updates.  Javascript Session Establishment Protocol
   specification [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.

   The following sections provide samples of SDP message details and
   exchanges for the most common WebRTC usecases.





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5.  WebRTC Session Description Examples

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

      It has zero or more Audio only,Video only or Audio/Video Media
      streams
      MAY contain zero or more non-media data streams
      All the streams are secured with DTLS/SRTP
      ICE processing for NAT Traversal
      Sessions over IPv4-only, IPv6-only, dual-stack based clients.

   As mentioned earlier [WEBRTC] proposes using SDP based Offer/Answer
   model to negotiate multimedia session between peers' browsers
   Building on the concepts from the previous sections, the following
   subsections attempts to describe the usage of SDP for the most common
   WebRTC use-cases.

   In all the use-cases, Alice and Bob are assumed to be the WebRTC
   peers unless mentioned otherwise.  Pointers to appropriate RFCs and
   notes are provided, wherever necessary,agains the SDP lines.

5.1.  Secure Two-Way Audio,Video and Data with RTCP Feedback

   This use-case allows two users to participate in a two-way
   communication session securely on their WebRTC enabled Web browsers.

   title WebRTC Session - 2-Way Secure Audio,Video with RTCP Feedback
   Alice->Bob: Offer(Audio:G.711,Opus,iLBC Video:H.264,VP8)
   Bob->Alice: Answer(Audio:Opus,DTMF Video:H.264)
   Alice->Bob: Two-way Opus Audio, H.264 Video
   note right of Alice
     Session also suports RTP/RTCP Mux, RTCP feedback (nack,pli)
   end note

   More specifically, this use-case demonstrates following aspects of a
   WebRTC session
      SRTP with DTLS based encryption
      RTP and RTCP Muxing
      RTCP based feedback and reduced size support
      ICE processing for NAT Traversal
      Audio Codec Offered :  PCMU, Opus, iLBC
      Audio Codec Answered :  Opus
      Video Codecs Offered:  H.264, VP8
      Video Codecs Answered:  H.264
      Data Channel Support
   The tables (4.1 and 4.2) below capture in detail, the initial SDP
   Offer and Answer messages exchanged.



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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=alice 20518 0 IN IP4 0.0.0.0           | [RFC4566] - Session    |
   |                                          | Origin Information     |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:074c6550                     | [RFC5245] - Session    |
   |                                          | Level ICE parameter    |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474af08a | [RFC5245] - Session    |
   | 068                                      | Level ICE parameter    |
   | a=fingerprint:sha-1                      | [RFC5245] - Session    |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 | DTLS Fingerprint for   |
   | 0:9d:1f:66:79:a8:07                      | SRTP                   |
   | a=rtcp-rsize                             | [RFC5506] - Alice      |
   |                                          | intends to use reduced |
   |                                          | size RTCP for this     |
   |                                          | session                |
   | m=audio 54609 RTP/SAVPF 0 109 98         | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:0 PCMU/8000                     | [RFC3551]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=rtpmap:98 iLBC/8000 a=fmtp:98 mode=20  | [RFC3952]              |
   | a=sendrecv                               | [RFC3264] - Alice can  |
   |                                          | send and recv audio    |
   | a=rtcp-mux                               | [RFC5761] - Alice can  |
   |                                          | perform RTP/RTCP       |
   |                                          | Muxing on port 54609   |
   | b=AS:256                                 | [RFC4566]              |
   | b=RS:0                                   | [RFC3556]              |
   | b=RR:0                                   | [RFC3556]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245] - Host ICE   |
   | 192.168.1.4 54609 typ host               | Candidate              |
   | a=candidate:1 1 UDP 694302207            | [RFC5245] - Server     |
   | 24.23.204.141 54609 typ srflx raddr      | Reflexive ICE          |
   | 192.168.1.4 rport 54609                  | Candidate for the      |
   |                                          | above host candidate   |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245] - Second     |
   | 192.168.1.4 64678 typ host               | Host Candidate         |
   | a=candidate:1 2 UDP 1694302206           | [RFC5245] -Server      |
   | 24.23.204.141 64678 typ srflx raddr      | Reflexive Candidate    |
   | 192.168.1.4 rport 64678                  | for the Second Host    |
   |                                          | Candidate              |




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   | a=rtcp-fb:109 nack                       | [RFC5104] - Indicates  |
   |                                          | NACK RTCP feedback     |
   |                                          | support                |
   | m=video 62537 RTP/SAVPF 99 120           | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:99 H264/90000                   | [RFC3984]              |
   | a=fmtp:99                                | [RFC3984]              |
   | profile-level-id=4d0028;packetization-mo |                        |
   | de=1                                     |                        |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264] - Alice can  |
   |                                          | send and recv video    |
   | a=rtcp-mux                               | [RFC5761] - Alice can  |
   |                                          | perform RTP/RTCP       |
   |                                          | Muxing on port 62537   |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 62537 typ host               |                        |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 24.23.204.141 62537 typ srflx raddr      |                        |
   | 192.168.1.4 rport 62537                  |                        |
   | 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: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=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                |
   | m=application 56966 SCTP/DTLS 5000       | [draft-ietf-rtcweb-dat |
   |                                          | a-channel]             |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=fmtp:5000                              | [draft-ietf-rtcweb-dat |
   | protocol=webrtc-datachannel;streams=16   | a-channel]             |




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   | a=sendrecv                               | [RFC3264] - Alice can  |
   |                                          | send and recv          |
   |                                          | non-media data         |
   | a=rtcp-mux                               | [RFC5761] - Alice can  |
   |                                          | perform RTP/RTCP       |
   |                                          | Muxing on port 56966   |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 56966 typ host               |                        |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 24.23.204.141 56966 typ srflx raddr      |                        |
   | 192.168.1.7 rport 56966                  |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.7 51641 typ host               |                        |
   | a=candidate:1 2 UDP 1694302206           | [RFC5245]              |
   | 24.23.204.141 51641 typ srflx raddr      |                        |
   | 192.168.1.7 rport 51641                  |                        |
   | a=rtcp-fb:5000 nack                      | [RFC5104] - Indicates  |
   |                                          | NACK feedback support  |
   |                                          | for the data-channel   |
   +------------------------------------------+------------------------+

                          Table 1: 4.1 SDP Offer





























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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=bob 16833 0 IN IP4 0.0.0.0             | [RFC4566] - Session    |
   |                                          | Origin Information     |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:c300d85b                     | [RFC5245] - Session    |
   |                                          | Level ICE username     |
   |                                          | frag                   |
   | a=ice-pwd:de4e99bd291c325921d5d47efbabd9 | [RFC5245] - Session    |
   | a2                                       | Level ICE password     |
   | a=fingerprint:sha-1                      | [RFC5245] - Session    |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 | DTLS Fingerprint for   |
   | 0:9d:1f:66:79:a8:07                      | SRTP                   |
   | a=rtcp-rsize                             | [RFC5506] - Alice      |
   |                                          | intends to use reduced |
   |                                          | size RTCP for this     |
   |                                          | session                |
   | m=audio 49203 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 98.248.92.77                   | [RFC4566]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264] - Bob can    |
   |                                          | send and recv audio    |
   | a=rtcp-mux                               | [RFC5761] - Bob can    |
   |                                          | perform RTP/RTCP       |
   |                                          | Muxing on port 49203   |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245] - Host ICE   |
   | 192.168.1.7 49203 typ host               | Candidate for Opus     |
   |                                          | Stream                 |
   | a=ccandidate:1 1 UDP 1694302207          | [RFC5245] - Server     |
   | 98.248.92.77 49203 typ srflx raddr       | Reflexive ICE          |
   | 192.168.1.7 rport 49203                  | Candidate for the      |
   |                                          | above host candidate   |
   | a=candidate:candidate:0 2 UDP 2113667326 | [RFC5245] - Second     |
   | 192.168.1.7 60065 typ host               | Host Candidate         |
   | a=candidate:1 2 UDP 1694302206           | [RFC5245] -Server      |
   | 98.248.92.77 60065 typ srflx raddr       | Reflexive Candidate    |
   | 192.168.1.7 rport 60065                  | for the Second Host    |
   |                                          | Candidate              |
   | m=video 63130 RTP/SAVPF 99               | [RFC4566]              |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=rtpmap:99 H264/90000                   | [RFC3984]              |




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   | a=fmtp:99                                | [RFC3984]              |
   | profile-level-id=4d0028;packetization-mo |                        |
   | de=1                                     |                        |
   | a=sendrecv                               | [RFC3264] - Bob can    |
   |                                          | send and recv video    |
   | a=rtcp-mux                               | [RFC5761] - Bob can    |
   |                                          | perform RTP/RTCP       |
   |                                          | Muxing on port 63130   |
   | 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: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                |
   | m=application 55700 SCTP/DTLS 5000       | [draft-ietf-rtcweb-dat |
   |                                          | a-channel]             |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=fmtp:5000                              | [draft-ietf-rtcweb-dat |
   | protocol=webrtc-datachannel;streams=16   | a-channel]             |
   | a=sendrecv                               | [RFC3264] - Bob can    |
   |                                          | send and recv          |
   |                                          | non-media data         |
   | a=rtcp-mux                               | [RFC5761] - Bob can    |
   |                                          | perform RTP/RTCP       |
   |                                          | Muxing on port 55700   |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245] - Refer 4.1  |
   | 192.168.1.7 55700 typ host               | SDP Offer              |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245] Refer 4.1    |
   | 98.248.92.77 55700 typ srflx raddr       | SDP Offer              |
   | 192.168.1.7 rport 55700                  |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245] Refer 4.1    |
   | 192.168.1.7 58137 typ host               | SDP Offer              |
   | a=candidate:1 2 UDP 1694302206           | [RFC5245] Refer 4.1    |
   | 98.248.92.77 58137 typ srflx raddr       | SDP Offer              |
   | 192.168.1.7 rport 581371                 |                        |




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   | a=rtcp-fb:5000 nack                      | [RFC5104] - Indicates  |
   |                                          | NACK feedback support  |
   |                                          | for the data-channel   |
   +------------------------------------------+------------------------+

                          Table 2: 4.1 SDP Answer

5.2.  Secure Two-way Audio,Video,Data and remove data stream

   This scenario builds upon from the usecase in the section 5.1 It
   extends by Alice removing data-stream once the session is in
   progress.

   title WebRTC Session (Audio,Video,Datachannel) - Drop Datachannel
   note right of Alice
       Alice & Bob are in a two-way audio,video and datachannel session.
      Alice decides to stop the datachannel stream
   end note
   Alice->Bob: Offer(Audio:Opus Video:VP8, Application: Drop)
   Bob->Alice: Answer(Audio:Opus Video:VP8, Application:Drop)
   Alice->Bob: Two-way Opus Audio and VP8 Video

   As a precondition, A Two-Way Audio,Video and Data Session is already
   setup.

   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=alice 20519 0 IN IP4 0.0.0.0           | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:074c6550                     | [RFC5245]              |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474af08a | [RFC5245]              |
   | 068                                      |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 54609 RTP/SAVPF 0 109 98         | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:0 PCMU/8000                     | [RFC3551]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=rtpmap:98 iLBC/8000 a=fmtp:98 mode=20  | [RFC3952]              |
   | a=sendrecv                               | [RFC3264]              |



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   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 54609 typ host               |                        |
   | a=candidate:1 1 UDP 694302207            | [RFC5245]              |
   | 24.23.204.141 54609 typ srflx raddr      |                        |
   | 192.168.1.4 rport 54609                  |                        |
   | 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]              |
   | m=video 62537 RTP/SAVPF 99 120           | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:99 H264/90000                   | [RFC3984]              |
   | a=fmtp:99                                | [RFC3984]              |
   | profile-level-id=4d0028;packetization-mo |                        |
   | de=1                                     |                        |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 62537 typ host               |                        |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 24.23.204.141 62537 typ srflx raddr      |                        |
   | 192.168.1.4 rport 62537                  |                        |
   | 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:99 nack pli                    | [RFC5104]              |
   | a=rtcp-fb:99 ccm fir                     | [RFC5104]              |
   | a=rtcp-fb:120 nack pli                   | [RFC5104]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   | m=application 0 SCTP/DTLS 5000           | [draft-ietf-rtcweb-dat |
   |                                          | a-channel] - Port 0    |
   |                                          |  indicates dropping    |
   |                                          |  data stream           |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=fmtp:5000                              | [draft-ietf-rtcweb-dat |
   | protocol=webrtc-datachannel;streams=16   | a-channel]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 56966 typ host               |                        |




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   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 24.23.204.141 56966 typ srflx raddr      |                        |
   | 192.168.1.7 rport 56966                  |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.7 51641 typ host               |                        |
   | a=candidate:1 2 UDP 1694302206           | [RFC5245]              |
   | 24.23.204.141 51641 typ srflx raddr      |                        |
   | 192.168.1.7 rport 51641                  |                        |
   | a=rtcp-fb:5000 nack                      | [RFC5104]              |
   +------------------------------------------+------------------------+

             Table 3: 4.2 SDP Updated Offer w/DataChannel Drop







































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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=bob 16833 0 IN IP4 0.0.0.0             | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:c300d85b                     | [RFC5245]              |
   | a=ice-pwd:de4e99bd291c325921d5d47efbabd9 | [RFC5245]              |
   | a2                                       |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 49203 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 98.248.92.77                   | [RFC4566]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 49203 typ host               |                        |
   | a=ccandidate:1 1 UDP 1694302207          | [RFC5245]              |
   | 98.248.92.77 49203 typ srflx raddr       |                        |
   | 192.168.1.7 rport 49203                  |                        |
   | a=candidate: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                  |                        |
   | m=video 63130 RTP/SAVPF 99 120           | [RFC4566]              |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=rtpmap:99 H264/90000                   | [RFC3984]              |
   | a=fmtp:99                                | [RFC3984]              |
   | profile-level-id=4d0028;packetization-mo |                        |
   | de=1                                     |                        |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |
   | 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                  |                        |




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   | 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:99 nack pli                    | [RFC5104]              |
   | a=rtcp-fb:99 ccm fir                     | [RFC5104]              |
   | m=application 0 SCTP/DTLS 5000           | [draft-ietf-rtcweb-dat |
   |                                          | a-channel] Bob accepts |
   |                                          |  dropping the data     |
   |                                          |  stream                |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=fmtp:5000                              | [draft-ietf-rtcweb-dat |
   | protocol=webrtc-datachannel;streams=16   | a-channel]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 55700 typ host               |                        |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 98.248.92.77 55700 typ srflx raddr       |                        |
   | 192.168.1.7 rport 55700                  |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.7 58137 typ host               |                        |
   | a=candidate:1 2 UDP 1694302206           | [RFC5245]              |
   | 98.248.92.77 58137 typ srflx raddr       |                        |
   | 192.168.1.7 rport 581371                 |                        |
   | a=rtcp-fb:5000 nack                      | [RFC5104]              |
   +------------------------------------------+------------------------+

                      Table 4: 4.2 SDP Updated Answer

5.3.  Secure Two-Way Audio,Video w/Bundle

   This use-case demonstrates a successfull audio and video multiplexing
   scenario with SDP Bundle negotiation.

   The semantics of group:BUNLDE attribute would be defined for two
   different scenarios as follows
      Receiver Supports Bundle:  In this case, the receiver places a
      group:BUNDLE line in the answer and it sends all the media to the
      mids in the BUNDLE group to the port number identified for the
      m-line corresponding to the first mid in the BUNDLE group.  Thus,
      Alice recieves Audio and Video multiplexed onto the port 54609 as
      as per the example below.
      Receiver Doesn't Support Bundle:  In this case, the receiver
      doesn't include a group:BUNDLE attribute and audio/video RTP
      streams are sent to the appropriate ports specified in the offer.




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   title WebRTC Session - 2-Way Secure Audio,Video with Bundle
   Alice->Bob: Offer(Audio:Opus Video:VP8)
   Bob->Alice: Answer(Audio:Opus Video:VP8)
   Alice->Bob: Two-way Opus Audio, H.264 Video
   note right of Alice
     Session also suports RTP/RTCP Mux, RTCP feedback (nack,pli) with
     multiplexing of audio and video RTP data.
   end note

   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=alice 20518 0 IN IP4 0.0.0.0           | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:074c6550                     | [RFC5245]              |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474af08a | [RFC5245]              |
   | 068                                      |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | a=group:BUNDLE foo bar                   | [RFC5888]Alice         |
   |                                          | supports grouping of   |
   |                                          | m= lines               |
   | m=audio 54609 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=mid:foo                                | [RFC5888]Audio m= line |
   |                                          | part of Bundle group   |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 54609 typ host               |                        |
   | a=candidate:1 1 UDP 694302207            | [RFC5245]              |
   | 24.23.204.141 54609 typ srflx raddr      |                        |
   | 192.168.1.4 rport 54609                  |                        |
   | 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]              |
   | m=video 62537 RTP/SAVPF 120              | [RFC4566]              |



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   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=mid:bar                                | [RFC5888]Video m=line  |
   |                                          | part of the Bundle     |
   |                                          | group                  |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 62537 typ host               |                        |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 24.23.204.141 62537 typ srflx raddr      |                        |
   | 192.168.1.4 rport 62537                  |                        |
   | 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]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   +------------------------------------------+------------------------+

                      Table 5: 4.3 SDP Offer w/Bundle




























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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=bob 16833 0 IN IP4 0.0.0.0             | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:c300d85b                     | [RFC5245]              |
   | a=ice-pwd:de4e99bd291c325921d5d47efbabd9 | [RFC5245]              |
   | a2                                       |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | a=group:BUNDLE foo bar                   | Bob supports grouping  |
   |                                          | of m= lines and        |
   |                                          | indicates his interest |
   |                                          | in the same as well    |
   |                                          | [RFC5888]              |
   | m=audio 49203 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 98.248.92.77                   | [RFC4566]              |
   | a=mid:foo                                | [RFC5888]Audio m=line  |
   |                                          | part of the Bundle     |
   |                                          | group                  |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264]              |
   | 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: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                  |                        |
   | m=video 63130 RTP/SAVPF 120              | [RFC4566]              |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=mid:bar                                | [RFC5888]Video m=line  |
   |                                          | part of the Bundle     |
   |                                          | group                  |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |



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   | 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                  |                        |
   +------------------------------------------+------------------------+

                     Table 6: 4.3 SDP Answer w/Bundle

5.4.  Successful One Way Session with 2 Video Streams

   In this scenario Alice and Bob engage in one-way multimedia session
   with Bob receiving two video streams, one corresponding to Alice's
   video and other corresponding to her presentation slides.

   title 1 Way Audio & Video w/2 Video Streams
   note right of Alice
   Alice offers 2 sendonly video streams
   one for her video feed and other for her presentation slides.
   end note
   Alice->Bob: Offer(Audio:Opus, Video1,2: VP8)
   note right of Bob
   Bob accepts Alice's offer
   end note
   Bob->Alice: Answer(Audio:Opus, Video1,2: VP8)
   Alice->Bob: One-way Opus Audio, VP8 Video
   note right of Alice
   Bob can hear Alice and see her video feed as well
   as her presentation slides.
   end note















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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=alice 20519 0 IN IP4 0.0.0.0           | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:074c6550                     | [RFC5245]              |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474af08a | [RFC5245]              |
   | 068                                      |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 54609 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendonly                               | [RFC3264] - Send only  |
   |                                          | audio stream           |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 54609 typ host               |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.4 64678 typ host               |                        |
   | a=rtcp-fb:109 nack                       | [RFC5104]              |
   | m=video 62537 RTP/SAVPF 120              | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=content:speaker                        | [RFC4796] - Stream 1   |
   |                                          | for Alice's video      |
   | a=sendonly                               | [RFC3264] - Send only  |
   |                                          | video stream           |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 62537 typ host               |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.4 54721 typ host               |                        |
   | a=rtcp-fb:120 nack pli                   | [RFC5104]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   | m=video 62539 RTP/SAVPF 120              | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |




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   | a=content:slides                         | [RFC4796] - Stream 2   |
   |                                          | for Alice's slides     |
   | a=sendonly                               | [RFC3264] - Send only  |
   |                                          | video stream           |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 62539 typ host               |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.4 54723 typ host               |                        |
   | a=rtcp-fb:120 nack pli                   | [RFC5104]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   +------------------------------------------+------------------------+

                          Table 7: 4.4 SDP Offer





































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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=bob 16833 0 IN IP4 0.0.0.0             | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:c300d85b                     | [RFC5245]              |
   | a=ice-pwd:de4e99bd291c325921d5d47efbabd9 | [RFC5245]              |
   | a2                                       |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 49203 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 98.248.92.77                   | [RFC4566]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=recvonly                               | [RFC3264] - Receive    |
   |                                          | only audio stream      |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 49203 typ host               |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.7 60065 typ host               |                        |
   | m=video 63130 RTP/SAVPF 120              | [RFC4566]              |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=content:speaker                        | [RFC4796] - Stream 1   |
   |                                          | for Alice's Video      |
   | a=recvonly                               | [RFC3264] - Receive    |
   |                                          | Only Video Stream 1    |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 63130 typ host               |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.7 56607 typ host               |                        |
   | a=rtcp-fb:120 nack pli                   | [RFC5104]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   | m=video 63133 RTP/SAVPF 120              | [RFC4566]              |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=content:slides                         | [RFC4796] - Stream 2   |
   |                                          | for Alice's Slides     |



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   | a=recvonly                               | [RFC3264] - Receive    |
   |                                          | Only Video Stream 2    |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 63133 typ host               |                        |
   | a=candidate:0 2 UDP 2113667326           | [RFC5245]              |
   | 192.168.1.7 56609 typ host               |                        |
   | a=rtcp-fb:120 nack pli                   | [RFC5104]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   +------------------------------------------+------------------------+

                          Table 8: 4.4 SDP Answer

5.5.  Add New Media (video)

   This scenario describes the message exchanges when Alice decides to
   add video to an existing audio-only session

   title Add New Media(Video)
   Alice->Bob: Offer(Audio:G.711,Opus,iLBC)
   Bob->Alice: Answer(Audio:Opus)
   Alice->Bob: Two-way Opus Audio
   note right of Alice
   Alice decides to add Video
   end note
   Alice->Bob: Offer(Audio:G.711,Opus,iLBC Video:VP8)
   Bob->Alice: Answer(Audio:Opus, Video:VP8)
   Alice->Bob: Two-way Opus Audio, VP8 Video























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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=alice 20519 0 IN IP4 0.0.0.0           | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:074c6550                     | [RFC5245]              |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474af08a | [RFC5245]              |
   | 068                                      |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 54609 RTP/SAVPF 0 109 98         | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:0 PCMU/8000                     | [RFC3551]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=rtpmap:98 iLBC/8000 a=fmtp:98 mode=20  | [RFC3952]              |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | b=AS:256                                 | [RFC4566]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 54609 typ host               |                        |
   | a=candidate:1 1 UDP 694302207            | [RFC5245]              |
   | 24.23.204.141 54609 typ srflx raddr      |                        |
   | 192.168.1.4 rport 54609                  |                        |
   | 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]              |
   +------------------------------------------+------------------------+

                 Table 9: 4.5 SDP Initial Audio Only Offer












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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=bob 16833 0 IN IP4 0.0.0.0             | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:c300d85b                     | [RFC5245]              |
   | a=ice-pwd:de4e99bd291c325921d5d47efbabd9 | [RFC5245]              |
   | a2                                       |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 49203 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 98.248.92.77                   | [RFC4566]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 49203 typ host               |                        |
   | a=ccandidate:1 1 UDP 1694302207          | [RFC5245]              |
   | 98.248.92.77 49203 typ srflx raddr       |                        |
   | 192.168.1.7 rport 49203                  |                        |
   | a=candidate: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                  |                        |
   +------------------------------------------+------------------------+

                   Table 10: 4.5 SDP Answer- Audio Only

   Alice decides to add Video to the current session














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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=alice 20520 0 IN IP4 0.0.0.0           | [RFC4566] - Increased  |
   |                                          | Version Number         |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:074c6550                     | [RFC5245]              |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474af08a | [RFC5245]              |
   | 068                                      |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 54609 RTP/SAVPF 0 109 98         | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:0 PCMU/8000                     | [RFC3551]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=rtpmap:98 iLBC/8000 a=fmtp:98 mode=20  | [RFC3952]              |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 54609 typ host               |                        |
   | a=candidate:1 1 UDP 694302207            | [RFC5245]              |
   | 24.23.204.141 54609 typ srflx raddr      |                        |
   | 192.168.1.4 rport 54609                  |                        |
   | 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]              |
   | m=video 62537 RTP/SAVPF120               | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 62537 typ host               |                        |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 24.23.204.141 62537 typ srflx raddr      |                        |
   | 192.168.1.4 rport 62537                  |                        |




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   | 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]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   +------------------------------------------+------------------------+

                  Table 11: 4.5 SDP Updated Offer w/Video

   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=bob 16833 0 IN IP4 0.0.0.0             | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:c300d85b                     | [RFC5245]              |
   | a=ice-pwd:de4e99bd291c325921d5d47efbabd9 | [RFC5245]              |
   | a2                                       |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 49203 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 98.248.92.77                   | [RFC4566]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 49203 typ host               |                        |
   | a=ccandidate:1 1 UDP 1694302207          | [RFC5245]              |
   | 98.248.92.77 49203 typ srflx raddr       |                        |
   | 192.168.1.7 rport 49203                  |                        |
   | a=candidate: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                  |                        |
   | m=video 63130 RTP/SAVPF 99 120           | [RFC4566]              |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |



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   | 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                  |                        |
   +------------------------------------------+------------------------+

                     Table 12: 4.5 SDP Updated Answer


6.  WebRTC <-> Legacy Interop Examples

   In this section, we attempt to provide session descriptions
   showcasing inter-operability between a WebRTC end-point and a Legacy
   VOIP end-point.  The ideas included in here are not fully baked into
   the standards and might be controversial in nature.  The hope here is
   to demonstrate a plausible SDP composition to enchance seamless
   inter-operability between the aforementioned communication systems.

6.1.  Secure Two-Way Audio,Video w/Feedback - WebRTC <-> Legacy Interop

   In the scenario desribed below, Alice sends [RFC3264] Offer with two
   sets of media descriptions per media type.
      One set that correponds to [WEBRTC] Compliant RTP/SAVPF based
      audio and video descriptions.
      Another set with RTP/AVP based audio and video descriptions for
      the legacy Interop purposes.
      Also to note, Alice includes session level DTLS information and
      media level RTCP feedback information as applicable to both the
      sets of media descriptions

   On the other hand, Bob being a Legacy VOIP end-point, recognizes only
   the media descriptions with RTP/AVP as the application protocol.  The
   security and fedback requirements for the session are either handled
   by a intermediate gateway or with some combination of Bob's
   capabilities and the intermediate gateway.









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   title Successful 2-Way WebRTC <-> VOIP Interop
   note right of Alice
   Alice is on a WebRTC end-point & Bob is behind a legacy VOIP system
   end note
   Alice->Bob: Offer(Audio:Opus Video:VP8)
   note right of Alice
    Alice includes 2 copies of media descriptions
    1. WebRTC compliant media description (RTP/SAVPF)
    2. Legacy compliant media description (RTP/AVP)
   end note
   Bob->Alice: Answer(Audio:Opus Video:VP8)
   note right of Bob
    Bob recognizes"legacy compliant" media description from Alice.
    and accepts the same.
   end note
   Alice->Bob: Two-way Opus Audio, VP8 Video
   note right of Alice
     Session also suports RTP/RTCP Mux, RTCP feedback (nack,pli)
   end note

   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=alice 20518 0 IN IP4 0.0.0.0           | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:074c6550                     | [RFC5245]              |
   | a=ice-pwd:a28a397a4c3f31747d1ee3474af08a | [RFC5245]              |
   | 068                                      |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtcp-rsize                             | [RFC5506]              |
   | m=audio 54609 RTP/SAVPF 109              | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 54609 typ host               |                        |
   | a=candidate:1 1 UDP 694302207            | [RFC5245]              |
   | 24.23.204.141 54609 typ srflx raddr      |                        |
   | 192.168.1.4 rport 54609                  |                        |




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   | 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]              |
   | m=video 62537 RTP/SAVPF 120              | [RFC4566]              |
   | c= IN IP4 24.23.204.141                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |
   | a=rtcp-mux                               | [RFC5761]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.4 62537 typ host               |                        |
   | a=candidate:1 1 UDP 1694302207           | [RFC5245]              |
   | 24.23.204.141 62537 typ srflx raddr      |                        |
   | 192.168.1.4 rport 62537                  |                        |
   | 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]              |
   | a=rtcp-fb:120 ccm fir                    | [RFC5104]              |
   | ---------------                          | These set of media     |
   |                                          | descriptions are for   |
   |                                          | Legacy Inter-op        |
   |                                          | purposes               |
   | 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-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:7f:7d:f9:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtpmap:109 opus/48000                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | 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                  |                        |



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   | 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       |
   | 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-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:7d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | 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 13: 5.1 SDP Offer











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   +------------------------------------------+------------------------+
   | SDP Contents                             | RFC#/Notes             |
   +------------------------------------------+------------------------+
   | v=0                                      | [RFC4566]              |
   | o=bob 16833 0 IN IP4 0.0.0.0             | [RFC4566]              |
   | s=                                       | [RFC4566]              |
   | t=0 0                                    | [RFC4566]              |
   | a=ice-ufrag:c300d85b                     | [RFC5245]              |
   | a=ice-pwd:de4e99bd291c325921d5d47efbabd9 | [RFC5245]              |
   | a2                                       |                        |
   | a=fingerprint:sha-1                      | [RFC5245]              |
   | 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:7 |                        |
   | 0:9d:1f:66:79:a8:07                      |                        |
   | 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                  | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=ptime:20                               | [draft-spittka-payload |
   |                                          | -rtp-opus]             |
   | a=sendrecv                               | [RFC3264]              |
   | a=candidate:0 1 UDP 2113667327           | [RFC5245]              |
   | 192.168.1.7 49203 typ host               |                        |
   | a=ccandidate:1 1 UDP 1694302207          | [RFC5245]              |
   | 98.248.92.77 49203 typ srflx raddr       |                        |
   | 192.168.1.7 rport 49203                  |                        |
   | a=candidate: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                  |                        |
   | m=video 63130 RTP/SAVP 120               | [RFC4566] Bob accepts  |
   |                                          | RTP/AVP based video    |
   |                                          | stram                  |
   | c= IN IP4 98.248.92.771                  | [RFC4566]              |
   | a=rtpmap:120 VP8/90000                   | [draft-ietf-payload-vp |
   |                                          | 8]                     |
   | a=sendrecv                               | [RFC3264]              |
   | 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               |                        |





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   | a=candidate:1 2 UDP 1694302206           | [RFC5245]              |
   | 98.248.92.77 56607 typ srflx raddr       |                        |
   | 192.168.1.7 rport 56607                  |                        |
   +------------------------------------------+------------------------+

                         Table 14: 5.1 SDP Answer


7.  IANA Considerations

   This document requires no actions from IANA.


8.  References

8.1.  Normative References

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264,
              June 2002.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

8.2.  Informative References

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245,
              July 2006.

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

   [JSEP]     Uberti, J. and C. Jennigs, "Javascript Session
              Establishment Protocol", draft-ietf-rtcweb-jsep-01 (work
              in progress), December 2012.

   [RFC5506]  Johansson, I., "Support for Reduced-Size Real-Time
              Transport Control Protocol (RTCP): Opportunities and
              Consequences", RFC 5506, April 2009.

   [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
              Video Conferences with Minimal Control", RFC 3551,



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              July 2003.

   [RFC3952]  Duric, A. and S. Andersen, "Real-time Transport Protocol
              (RTP) Payload Format for internet Low Bit Rate Codec
              (iLBC) Speech", RFC 3952, December 2004.

   [RFC4796]  Hautakorpi, J. and G. Camarillo, "The Session Description
              Protocol (SDP) Content Attribute", RFC 4796,
              February 2007.

   [RFC5761]  Perkins, C. and M. Westerlund, "Multiplexing RTP Data and
              Control Packets on a Single Port", RFC 5761, April 2010.

   [RFC3556]  Casner, S., "Session Description Protocol (SDP) Bandwidth
              Modifiers for RTP Control Protocol (RTCP) Bandwidth",
              RFC 3556, July 2003.

   [RFC5104]  Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
              "Codec Control Messages in the RTP Audio-Visual Profile
              with Feedback (AVPF)", RFC 5104, February 2008.

   [RFC5888]  Camarillo, G. and H. Schulzrinne, "RTP Payload Format for
              H.264 Video", RFC 3984, June 2010.

   [draft-spittka-payload-rtp-opus]
               Spittka, J., Vos, K., and JM. Valin, "RTP Payload Format
              for Opus Speech and Audio Codec",
              draft-spittka-payload-rtp-opus-01 (work in progress),
              July 2012.

   [draft-ietf-payload-vp8]
              Westin, P., Lundin, H., Glover, M., Uberti, J., and F.
              Galligan, "RTP Payload Format for VP8 Video",
              draft-ietf-payload-vp8-05 (work in progress), August 2012.

   [RFC3984]  Wenger, S., Hannuksela, M., Stockhammer, T., Westerlund,
              M., and D. Singer, "RTP Payload Format for H.264 Video",
              RFC 3984, February 2005.

   [draft-ietf-rtcweb-data-channel]
              Jesup, R., Loreto, S., and M. Tuexen, "RTCWeb Datagram
              Connection", draft-ietf-rtcweb-data-channel-01 (work in
              progress), September 2012.








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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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