--- 1/draft-ietf-mmusic-duplication-grouping-01.txt 2013-05-27 12:14:20.058157674 +0100 +++ 2/draft-ietf-mmusic-duplication-grouping-02.txt 2013-05-27 12:14:20.078158170 +0100 @@ -1,88 +1,88 @@ MMUSIC A. Begen Internet-Draft Cisco Intended status: Standards Track Y. Cai -Expires: September 21, 2013 Microsoft +Expires: November 28, 2013 Microsoft H. Ou Cisco - March 20, 2013 + May 27, 2013 Duplication Grouping Semantics in the Session Description Protocol - draft-ietf-mmusic-duplication-grouping-01 + draft-ietf-mmusic-duplication-grouping-02 Abstract Packet loss is undesirable for real-time multimedia sessions, but can occur due to congestion, or other unplanned network outages. This is especially true for IP multicast networks, where packet loss patterns can vary greatly between receivers. One technique that can be used to recover from packet loss without incurring unbounded delay for all the receivers is to duplicate the packets and send them in separate redundant streams. This document defines the semantics for grouping redundant streams in the Session Description Protocol (SDP). The semantics defined in this document are to be used with the SDP Grouping Framework [RFC5888]. SSRC-level (Synchronization Source) grouping semantics are also defined in this document for RTP streams using SSRC multiplexing. -Status of this Memo +Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on September 21, 2013. + This Internet-Draft will expire on November 28, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . . 3 - 3. Duplication Grouping . . . . . . . . . . . . . . . . . . . . . 3 - 3.1. "DUP" Grouping Semantics . . . . . . . . . . . . . . . . . 3 - 3.2. Duplication Grouping for SSRC-Multiplexed RTP Streams . . . 4 - 3.3. SDP Offer/Answer Model Considerations . . . . . . . . . . . 4 - 4. SDP Examples . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 4.1. Separate Source Addresses . . . . . . . . . . . . . . . . . 5 - 4.2. Separate Destination Addresses . . . . . . . . . . . . . . 5 - 4.3. Temporal Redundancy . . . . . . . . . . . . . . . . . . . . 6 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 - 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 8.1. Normative References . . . . . . . . . . . . . . . . . . . 8 - 8.2. Informative References . . . . . . . . . . . . . . . . . . 8 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 + 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3 + 3. Duplication Grouping . . . . . . . . . . . . . . . . . . . . 3 + 3.1. "DUP" Grouping Semantics . . . . . . . . . . . . . . . . 3 + 3.2. Duplication Grouping for SSRC-Multiplexed RTP Streams . . 3 + 3.3. SDP Offer/Answer Model Considerations . . . . . . . . . . 4 + 4. SDP Examples . . . . . . . . . . . . . . . . . . . . . . . . 4 + 4.1. Separate Source Addresses . . . . . . . . . . . . . . . . 4 + 4.2. Separate Destination Addresses . . . . . . . . . . . . . 5 + 4.3. Temporal Redundancy . . . . . . . . . . . . . . . . . . . 5 + 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 + 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 7 + 8.2. Informative References . . . . . . . . . . . . . . . . . 8 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction The Real-time Transport Protocol (RTP) [RFC3550] is widely used today for delivering IPTV traffic, and other real-time multimedia sessions. Many of these applications support very large numbers of receivers, and rely on intra-domain UDP/IP multicast for efficient distribution of traffic within the network. While this combination has proved successful, there does exist a @@ -176,43 +176,43 @@ retry the request with an offer without the duplication grouping. This behavior is specified in [RFC5888]. 4. SDP Examples 4.1. Separate Source Addresses In this example, the redundant streams use the same IP destination address (232.252.0.1) but they are sourced from different addresses (198.51.100.1 and 198.51.100.2). Thus, the receiving host needs to - join both SSM sessions separately. + join both source-specific multicast (SSM) sessions separately. v=0 o=ali 1122334455 1122334466 IN IP4 dup.example.com s=DUP Grouping Semantics t=0 0 m=video 30000 RTP/AVP 100 c=IN IP4 232.252.0.1/127 a=source-filter:incl IN IP4 232.252.0.1 198.51.100.1 198.51.100.2 a=rtpmap:100 MP2T/90000 a=ssrc:1000 cname:ch1@example.com a=ssrc:1010 cname:ch1@example.com a=ssrc-group:DUP 1000 1010 a=mid:Ch1 Note that in actual use, SSRC values, which are random 32-bit numbers, can be much larger than the ones shown in this example. Also note that this SDP description does not use the 'duplication- delay' attribute (defined in [I-D.ietf-mmusic-delayed-duplication]) since the sender does not apply any delay between the redundant - streams upon transmission. Alternatively, one could be more explicit - and insert an "a=duplication-delay:0" line before the "a=mid:Ch1" - line. + streams upon transmission. Alternatively, one MAY explicitly insert + an "a=duplication-delay:0" line before the "a=mid:Ch1" line for + informational purposes. 4.2. Separate Destination Addresses In this example, the redundant streams have different IP destination addresses. The example shows the same UDP port number and IP source address for each stream, but either or both could have been different for the two streams. v=0 o=ali 1122334455 1122334466 IN IP4 dup.example.com @@ -291,28 +290,29 @@ Token Semantics Reference ------- ----------------------------- --------- DUP Duplication [RFCXXXX] 7. Acknowledgments The authors would like to thank Colin Perkins, Bill Ver Steeg, Dave Oran and Toerless Eckert for their inputs and suggestions. 8. References + 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model - with Session Description Protocol (SDP)", RFC 3264, - June 2002. + with Session Description Protocol (SDP)", RFC 3264, June + 2002. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006. [RFC5576] Lennox, J., Ott, J., and T. Schierl, "Source-Specific Media Attributes in the Session Description Protocol @@ -323,23 +323,23 @@ 8.2. Informative References [I-D.ietf-avtext-rtp-duplication] Begen, A. and C. Perkins, "Duplicating RTP Streams", draft-ietf-avtext-rtp-duplication-01 (work in progress), December 2012. [I-D.ietf-mmusic-delayed-duplication] Begen, A., Cai, Y., and H. Ou, "Delayed Duplication - Attribute in the Session Description Protocol", - draft-ietf-mmusic-delayed-duplication-00 (work in - progress), October 2012. + Attribute in the Session Description Protocol", draft- + ietf-mmusic-delayed-duplication-01 (work in progress), + March 2013. [IC2011] Evans, J., Begen, A., Greengrass, J., and C. Filsfils, "Toward Lossless Video Transport (to appear in IEEE Internet Computing)", November 2011. [RFC2354] Perkins, C. and O. Hodson, "Options for Repair of Streaming Media", RFC 2354, June 1998. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.