--- 1/draft-ietf-mmusic-duplication-grouping-02.txt 2013-07-11 07:14:33.958304888 -0700 +++ 2/draft-ietf-mmusic-duplication-grouping-03.txt 2013-07-11 07:14:33.978305381 -0700 @@ -1,53 +1,53 @@ MMUSIC A. Begen Internet-Draft Cisco Intended status: Standards Track Y. Cai -Expires: November 28, 2013 Microsoft +Expires: January 12, 2014 Microsoft H. Ou Cisco - May 27, 2013 + July 11, 2013 Duplication Grouping Semantics in the Session Description Protocol - draft-ietf-mmusic-duplication-grouping-02 + draft-ietf-mmusic-duplication-grouping-03 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. + Grouping Framework. SSRC-level (Synchronization Source) grouping + semantics are also defined in this document for RTP streams using + SSRC multiplexing. 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 November 28, 2013. + This Internet-Draft will expire on January 12, 2014. 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 @@ -113,22 +113,22 @@ [RFC2119]. 3. Duplication Grouping 3.1. "DUP" Grouping Semantics Each "a=group" line is used to indicate an association relationship between the redundant streams. The streams included in one "a=group" line are called a Duplication Group. - Using the framework in [RFC5888], this document defines "DUP" as the - grouping semantics for redundant streams. + Using the SDP Grouping Framework in [RFC5888], this document defines + "DUP" as the grouping semantics for redundant streams. The "a=group:DUP" semantics MUST be used to group the redundant streams except when the streams are specified in the same media description, i.e., in the same "m" line (See Section 3.2). In an "a=group:DUP" line, the order of the listed redundant streams does not strictly indicate the order of transmission, although it is RECOMMENDED that the stream listed first is sent first, with the other stream(s) being the (time-delayed) duplicate(s). 3.2. Duplication Grouping for SSRC-Multiplexed RTP Streams @@ -183,22 +183,22 @@ 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 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 + c=IN IP4 233.252.0.1/127 + a=source-filter:incl IN IP4 233.252.0.1 198.51.100.1 198.51.100.2 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]) @@ -318,28 +318,28 @@ Media Attributes in the Session Description Protocol (SDP)", RFC 5576, June 2009. [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description Protocol (SDP) Grouping Framework", RFC 5888, June 2010. 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. + draft-ietf-avtext-rtp-duplication-02 (work in progress), + March 2013. [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-01 (work in progress), - March 2013. + ietf-mmusic-delayed-duplication-02 (work in progress), May + 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.