--- 1/draft-ietf-mmusic-offer-answer-examples-00.txt 2006-02-05 00:26:45.000000000 +0100 +++ 2/draft-ietf-mmusic-offer-answer-examples-01.txt 2006-02-05 00:26:45.000000000 +0100 @@ -1,19 +1,19 @@ MMUSIC Working Group A. Johnston -Internet-Draft WorldCom -Expires: October 6, 2003 R. Sparks +Internet-Draft MCI +Expires: December 27, 2003 R. Sparks dynamicsoft - April 7, 2003 + June 28, 2003 Session Description Protocol Offer Answer Examples - draft-ietf-mmusic-offer-answer-examples-00 + draft-ietf-mmusic-offer-answer-examples-01 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. @@ -21,62 +21,66 @@ 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." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on October 6, 2003. + This Internet-Draft will expire on December 27, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document gives examples of Session Description Protocol (SDP) offer answer exchanges. Examples include codec negotiation and selection, hold and resume, and addition and deletion of media streams. The examples show multiple media types, bidirectional, unidirectional, inactive streams and dynamic payload types. Common Third Party Call Control (3pcc) examples are also given. Table of Contents - 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Codec Negotiation and Selection . . . . . . . . . . . . . . . 3 - 2.1 Audio and Video 1 . . . . . . . . . . . . . . . . . . . . . . 3 - 2.2 Audio and Video 2 . . . . . . . . . . . . . . . . . . . . . . 4 - 2.3 Audio and Video 3 . . . . . . . . . . . . . . . . . . . . . . 6 - 2.4 Two Audio Steams . . . . . . . . . . . . . . . . . . . . . . . 6 - 2.5 Audio and Video 4 . . . . . . . . . . . . . . . . . . . . . . 7 - 2.6 Audio Only 1 . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 2.7 Audio and Video 5 . . . . . . . . . . . . . . . . . . . . . . 9 - 2.8 Audio and Video 6 . . . . . . . . . . . . . . . . . . . . . . 11 - 3. Hold and Resume Scenarios . . . . . . . . . . . . . . . . . . 11 - 3.1 Hold and Unhold 1 . . . . . . . . . . . . . . . . . . . . . . 11 - 3.2 Hold with Two Streams . . . . . . . . . . . . . . . . . . . . 13 - 4. Addition and Deletion of Media Streams . . . . . . . . . . . . 14 - 4.1 Second Audio Stream Added . . . . . . . . . . . . . . . . . . 14 - 4.2 Audio then Video Added . . . . . . . . . . . . . . . . . . . . 15 - 4.3 Audio and Video, then Video Deleted . . . . . . . . . . . . . 16 - 5. Third Party Call Control (3pcc) . . . . . . . . . . . . . . . 18 - 5.1 No Media, then Audio Added . . . . . . . . . . . . . . . . . . 18 - 5.2 Hold and Unhold 2 . . . . . . . . . . . . . . . . . . . . . . 19 - 5.3 Hold and Unhold 3 . . . . . . . . . . . . . . . . . . . . . . 20 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21 - Informative References . . . . . . . . . . . . . . . . . . . . 21 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 21 - Intellectual Property and Copyright Statements . . . . . . . . 23 + 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 + 2. Codec Negotiation and Selection . . . . . . . . . . . . . . 3 + 2.1 Audio and Video 1 . . . . . . . . . . . . . . . . . . . . . 3 + 2.2 Audio and Video 2 . . . . . . . . . . . . . . . . . . . . . 4 + 2.3 Audio and Video 3 . . . . . . . . . . . . . . . . . . . . . 5 + 2.4 Two Audio Steams . . . . . . . . . . . . . . . . . . . . . . 6 + 2.5 Audio and Video 4 . . . . . . . . . . . . . . . . . . . . . 7 + 2.6 Audio Only 1 . . . . . . . . . . . . . . . . . . . . . . . . 8 + 2.7 Audio and Video 5 . . . . . . . . . . . . . . . . . . . . . 9 + 2.8 Audio and Video 6 . . . . . . . . . . . . . . . . . . . . . 10 + 2.9 Asymmetric Codec Types . . . . . . . . . . . . . . . . . . . 11 + 2.10 Asymmetric Attribute Values . . . . . . . . . . . . . . . . 12 + 3. Hold and Resume Scenarios . . . . . . . . . . . . . . . . . 13 + 3.1 Hold and Unhold 1 . . . . . . . . . . . . . . . . . . . . . 13 + 3.2 Hold with Two Streams . . . . . . . . . . . . . . . . . . . 14 + 4. Addition and Deletion of Media Streams . . . . . . . . . . . 16 + 4.1 Second Audio Stream Added . . . . . . . . . . . . . . . . . 16 + 4.2 Audio then Video Added . . . . . . . . . . . . . . . . . . . 17 + 4.3 Audio and Video, then Video Deleted . . . . . . . . . . . . 18 + 5. Third Party Call Control (3pcc) . . . . . . . . . . . . . . 19 + 5.1 No Media, then Audio Added . . . . . . . . . . . . . . . . . 20 + 5.2 Hold and Unhold 2 . . . . . . . . . . . . . . . . . . . . . 20 + 5.3 Hold and Unhold 3 . . . . . . . . . . . . . . . . . . . . . 22 + 6. Security Considerations . . . . . . . . . . . . . . . . . . 23 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23 + 8. Changes since -00 . . . . . . . . . . . . . . . . . . . . . 23 + Informative References . . . . . . . . . . . . . . . . . . . 23 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 24 + Intellectual Property and Copyright Statements . . . . . . . 25 1. Overview This document describes offer answer examples of Session Description Protocol (SDP) based on RFC 3264 [1]. The SDP in these examples are defined by RFC 2327 [2]. The offers and answers are assumed to be transported using a protocol such as Session Initiation Protocol (SIP) [3]. Examples include codec negotiation and selection, hold and resume, @@ -441,20 +440,130 @@ o=bob 2808844564 2808844564 IN IP4 host.biloxi.example.com s= c=IN IP4 host.biloxi.example.com t=0 0 m=audio 49174 RTP/AVP 0 a=rtpmap:0 PCMU/8000 m=video 49172 RTP/AVP 32 c=IN IP4 otherhost.biloxi.example.com a=rtpmap:32 MPV/90000 +2.9 Asymmetric Codec Types + + This scenario shows a video and audio session where it is desired to + agree on different audio and video codecs in each direction. An + example for the need to establish an asymmetric session is when + running over asymmetric bandwidth links such as ADSL. + + In this simplest case the logical association between the send-only + and the receive-only streams is expressed by specifying the same port + number in both m-lines. Because no explicit RTCP attribute [7] is + included, usage of the port number in sendonly direction, which + equals to the port number in recvonly direction, unambiguously hints + that the two m-lines share the same RTCP bidirectional stream and + belong to the same RTP session. + + Note: When the RTCP attribute needs to be used, alternative means for + association between the m-lines will be used [8]. + + [Offer] + + v=0 + o=alice 2890844526 2890844526 IN IP4 host.atlanta.example.com + s= + c=IN IP4 host.atlanta.example.com + t=0 0 + m=audio 49170 RTP/AVP 95 + a=rtpmap:95 iLBC + a=sendonly + m=audio 49170 RTP/AVP 0 8 + a=rtpmap:0 PCMU/8000 + a=rtpmap:8 PCMA/8000 + a=recvonly + m=video 51372 RTP/AVP 31 32 + a=rtpmap:31 H261/90000 + a=rtpmap:32 MPV/90000 + a=sendonly + m=video 51372 RTP/AVP 34 + a=rtpmap:34 H263/90000 + a=recvonly + + [Answer] + + v=0 + o=bob 2808844564 2808844564 IN IP4 host.biloxi.example.com + s= + c=IN IP4 host.biloxi.example.com + t=0 0 + m=audio 49178 RTP/AVP 95 + a=rtpmap:iLBC + a=recvonly + m=audio 49178 RTP/AVP 0 + a=rtpmap:0 PCMU/8000 + a=sendonly + m=video 51374 RTP/AVP 31 + a=rtpmap:31 H261/90000 + a=recvonly + m=video 51374 RTP/AVP 34 + a=rtpmap:34 H263/90000 + a=sendonly + +2.10 Asymmetric Attribute Values + + This scenario shows an audio session where it is desired to agree on + audio codecs with different parameters (attributes) in each + direction. An example for the need to establish an asymmetric session + is when running over asymmetric bandwidth links such as ADSL. + + In this simplest case the logical association between the send-only + and the receive-only streams is expressed by specifying the same port + number in both m-lines. Because no explicit RTCP attribute [7] is + included, usage of the port number in sendonly direction, which + equals to the port number in recvonly direction, unambiguously hints + that the two m-lines share the same RTCP bidirectional stream and + belong to the same RTP session. + + Note: When the RTCP attribute needs to be used, alternative means for + association between the m-lines will be used [8]. + + [Offer] + + v=0 + o=alice 2890844526 2890844526 IN IP4 host.atlanta.example.com + s= + c=IN IP4 host.atlanta.example.com + t=0 0 + m=audio 49170 RTP/AVP 97 + a=rtpmap:97 MPA + a=fmtp: 97 layer=3 bitrate=10 + a=sendonly + m=audio 49170 RTP/AVP 97 + a=rtpmap:97 MPA + a=fmtp:97 layer=3 bitrate=60 + a=recvonly + + [Answer] + + v=0 + o=bob 2808844564 2808844564 IN IP4 host.biloxi.example.com + s= + c=IN IP4 host.biloxi.example.com + t=0 0 + m=audio 49178 RTP/AVP 97 + a=rtpmap:MPA + a=fmtp:97 layer=3 bitrate=10 + a=recvonly + m=audio 49178 RTP/AVP 97 + a=rtpmap:MPA + a=fmtp:97 layer=3 bitrate=60 + a=sendonly + 3. Hold and Resume Scenarios 3.1 Hold and Unhold 1 Alice calls Bob, but Bob answers placing Alice on hold. Bob then takes Alice off hold in the second offer. Alice changes port number in the second exchange. The media session between Alice and Bob is now active after Alice's second answer. Note that a=sendrecv could be present in both second offer and answer exchange. This is a common flow in 3pcc [5] scenarios. @@ -874,51 +981,68 @@ 6. Security Considerations SDP offer and answer messages can contain private information about addresses and sessions to be established between parties. If this information needs to be kept private, some security mechanism in the protocol used to carry the offers and answers must be used. For SIP, this means using TLS transport and/or S/MIME encryption of the SDP message body. +7. Acknowledgements + + Thanks to Orit Levin for the asymmetrical codec and attribute + examples. + +8. Changes since -00 + + - Added asymmetrical codec and attribute examples + Informative References [1] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. [2] Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998. [3] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [4] Schulzrinne, H. and S. Petrack, "RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals", RFC 2833, May 2000. - [5] Rosenberg, J., Schulzrinne, H., Camarillo, G. and J. Peterson, + [5] Rosenberg, J., Peterson, J., Schulzrinne, H. and G. Camarillo, "Best Current Practices for Third Party Call Control in the Session Initiation Protocol", draft-ietf-sipping-3pcc-03 (work in progress), March 2003. [6] Duric, A. and S. Andersen, "RTP Payload Format for iLBC Speech", draft-ietf-avt-rtp-ilbc-01 (work in progress), March 2003. + [7] Huitema, C., "RTCP attribute in SDP", + draft-ietf-mmusic-sdp4nat-05 (work in progress), June 2003. + + [8] Camarillo, G., Eriksson, G., Holler, J. and H. Schulzrinne, + "Grouping of Media Lines in the Session Description Protocol + (SDP)", RFC 3388, December 2002. + Authors' Addresses Alan Johnston - WorldCom + MCI 100 South 4th Street St. Louis, MO 63102 - EMail: alan.johnston@wcom.com + EMail: alan.johnston@mci.com + Robert J. Sparks dynamicsoft 5100 Tennyson Parkway Suite 1200 Plano, TX 75024 EMail: rsparks@dynamicsoft.com Intellectual Property Statement @@ -963,14 +1087,14 @@ The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assignees. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. -Acknowledgement +Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society.