draft-ietf-mmusic-duplication-grouping-03.txt   draft-ietf-mmusic-duplication-grouping-04.txt 
MMUSIC A. Begen MMUSIC A. Begen
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track Y. Cai Intended status: Standards Track Y. Cai
Expires: January 12, 2014 Microsoft Expires: May 25, 2014 Microsoft
H. Ou H. Ou
Cisco Cisco
July 11, 2013 November 21, 2013
Duplication Grouping Semantics in the Session Description Protocol Duplication Grouping Semantics in the Session Description Protocol
draft-ietf-mmusic-duplication-grouping-03 draft-ietf-mmusic-duplication-grouping-04
Abstract Abstract
Packet loss is undesirable for real-time multimedia sessions, but can Packet loss is undesirable for real-time multimedia sessions, but can
occur due to congestion, or other unplanned network outages. This is occur due to congestion, or other unplanned network outages. This is
especially true for IP multicast networks, where packet loss patterns especially true for IP multicast networks, where packet loss patterns
can vary greatly between receivers. One technique that can be used can vary greatly between receivers. One technique that can be used
to recover from packet loss without incurring unbounded delay for all to recover from packet loss without incurring unbounded delay for all
the receivers is to duplicate the packets and send them in separate the receivers is to duplicate the packets and send them in separate
redundant streams. This document defines the semantics for grouping redundant streams. This document defines the semantics for grouping
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 12, 2014. This Internet-Draft will expire on May 25, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
3. Duplication Grouping . . . . . . . . . . . . . . . . . . . . 3 3. Duplication Grouping . . . . . . . . . . . . . . . . . . . . 3
3.1. "DUP" Grouping Semantics . . . . . . . . . . . . . . . . 3 3.1. "DUP" Grouping Semantics . . . . . . . . . . . . . . . . 3
3.2. Duplication Grouping for SSRC-Multiplexed RTP Streams . . 3 3.2. Duplication Grouping for SSRC-Multiplexed RTP Streams . . 3
3.3. SDP Offer/Answer Model Considerations . . . . . . . . . . 4 3.3. SDP Offer/Answer Model Considerations . . . . . . . . . . 4
4. SDP Examples . . . . . . . . . . . . . . . . . . . . . . . . 4 4. SDP Examples . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Separate Source Addresses . . . . . . . . . . . . . . . . 4 4.1. Separate Source Addresses . . . . . . . . . . . . . . . . 4
4.2. Separate Destination Addresses . . . . . . . . . . . . . 5 4.2. Separate Destination Addresses . . . . . . . . . . . . . 5
4.3. Temporal Redundancy . . . . . . . . . . . . . . . . . . . 5 4.3. Temporal Redundancy . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
The Real-time Transport Protocol (RTP) [RFC3550] is widely used today The Real-time Transport Protocol (RTP) [RFC3550] is widely used today
for delivering IPTV traffic, and other real-time multimedia sessions. for delivering IPTV traffic, and other real-time multimedia sessions.
Many of these applications support very large numbers of receivers, Many of these applications support very large numbers of receivers,
and rely on intra-domain UDP/IP multicast for efficient distribution and rely on intra-domain UDP/IP multicast for efficient distribution
of traffic within the network. of traffic within the network.
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A node that is receiving an offer from a sender may or may not A node that is receiving an offer from a sender may or may not
understand line grouping. It is also possible that the node understand line grouping. It is also possible that the node
understands line grouping but it does not understand the "DUP" understands line grouping but it does not understand the "DUP"
semantics. From the viewpoint of the sender of the offer, these semantics. From the viewpoint of the sender of the offer, these
cases are indistinguishable. cases are indistinguishable.
When a node is offered a session with the "DUP" grouping semantics When a node is offered a session with the "DUP" grouping semantics
but it does not support line grouping or the duplication grouping but it does not support line grouping or the duplication grouping
semantics, as per [RFC5888], the node responds to the offer either semantics, as per [RFC5888], the node responds to the offer either
(1) with an answer that ignores the grouping attribute or (2) with a (1) with an answer that omits the grouping attribute or (2) with a
refusal to the request (e.g., 488 Not Acceptable Here or 606 Not refusal to the request (e.g., 488 Not Acceptable Here or 606 Not
Acceptable in SIP). Acceptable in SIP).
In the first case, the original sender of the offer must send a new In the first case, the original sender of the offer must send a new
offer without any duplication grouping. In the second case, if the offer without any duplication grouping. In the second case, if the
sender of the offer still wishes to establish the session, it should sender of the offer still wishes to establish the session, it should
retry the request with an offer without the duplication grouping. retry the request with an offer without the duplication grouping.
This behavior is specified in [RFC5888]. This behavior is specified in [RFC5888].
4. SDP Examples 4. SDP Examples
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a=source-filter:incl IN IP4 233.252.0.1 198.51.100.1 a=source-filter:incl IN IP4 233.252.0.1 198.51.100.1
a=rtpmap:100 MP2T/90000 a=rtpmap:100 MP2T/90000
a=ssrc:1000 cname:ch1a@example.com a=ssrc:1000 cname:ch1a@example.com
a=ssrc:1010 cname:ch1a@example.com a=ssrc:1010 cname:ch1a@example.com
a=ssrc-group:DUP 1000 1010 a=ssrc-group:DUP 1000 1010
a=duplication-delay:50 a=duplication-delay:50
a=mid:Ch1 a=mid:Ch1
5. Security Considerations 5. Security Considerations
In general, the security considerations of [RFC4566] apply to this
document as well.
There is a weak threat for the receiver that the duplication grouping There is a weak threat for the receiver that the duplication grouping
can be modified to indicate relationships that do not exist. Such can be modified to indicate relationships that do not exist. Such
attacks might result in failure of the duplication mechanisms, and/or attacks might result in failure of the duplication mechanisms, and/or
mishandling of the media streams by the receivers. mishandling of the media streams by the receivers.
In order to avoid attacks of this sort, the SDP description needs to In order to avoid attacks of this sort, the SDP description needs to
be integrity protected and provided with source authentication. This be integrity protected and provided with source authentication. This
can, for example, be achieved on an end-to-end basis using S/MIME can, for example, be achieved on an end-to-end basis using S/MIME
[RFC5652] [RFC5751] when the SDP is used in a signaling packet using [RFC5652] [RFC5751] when the SDP is used in a signaling packet using
MIME types (application/sdp). Alternatively, HTTPS [RFC2818] or the MIME types (application/sdp). Alternatively, HTTPS [RFC2818] or the
authentication method in the Session Announcement Protocol (SAP) authentication method in the Session Announcement Protocol (SAP)
[RFC2974] could be used as well. [RFC2974] could be used as well. As for the confidentiality, if it
is desired, it can be useful to use a secure, encrypted transport
method to carry the SDP description.
6. IANA Considerations 6. IANA Considerations
This document registers the following semantics with IANA in This document registers the following semantics with IANA in
Semantics for the 'group' SDP Attribute under SDP Parameters: Semantics for the 'group' SDP Attribute under SDP Parameters:
Note to the RFC Editor: In the following registrations, please Note to the RFC Editor: In the following registrations, please
replace "XXXX" with the number of this document prior to publication replace "XXXX" with the number of this document prior to publication
as an RFC. as an RFC.
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Media Attributes in the Session Description Protocol Media Attributes in the Session Description Protocol
(SDP)", RFC 5576, June 2009. (SDP)", RFC 5576, June 2009.
[RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description [RFC5888] Camarillo, G. and H. Schulzrinne, "The Session Description
Protocol (SDP) Grouping Framework", RFC 5888, June 2010. Protocol (SDP) Grouping Framework", RFC 5888, June 2010.
8.2. Informative References 8.2. Informative References
[I-D.ietf-avtext-rtp-duplication] [I-D.ietf-avtext-rtp-duplication]
Begen, A. and C. Perkins, "Duplicating RTP Streams", Begen, A. and C. Perkins, "Duplicating RTP Streams",
draft-ietf-avtext-rtp-duplication-02 (work in progress), draft-ietf-avtext-rtp-duplication-04 (work in progress),
March 2013. October 2013.
[I-D.ietf-mmusic-delayed-duplication] [I-D.ietf-mmusic-delayed-duplication]
Begen, A., Cai, Y., and H. Ou, "Delayed Duplication Begen, A., Cai, Y., and H. Ou, "Delayed Duplication
Attribute in the Session Description Protocol", draft- Attribute in the Session Description Protocol", draft-
ietf-mmusic-delayed-duplication-02 (work in progress), May ietf-mmusic-delayed-duplication-02 (work in progress), May
2013. 2013.
[IC2011] Evans, J., Begen, A., Greengrass, J., and C. Filsfils, [IC2011] Evans, J., Begen, A., Greengrass, J., and C. Filsfils,
"Toward Lossless Video Transport (to appear in IEEE "Toward Lossless Video Transport, IEEE Internet Computing,
Internet Computing)", November 2011. vol. 15/6, pp. 48-57", November 2011.
[RFC2354] Perkins, C. and O. Hodson, "Options for Repair of [RFC2354] Perkins, C. and O. Hodson, "Options for Repair of
Streaming Media", RFC 2354, June 1998. Streaming Media", RFC 2354, June 1998.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC2974] Handley, M., Perkins, C., and E. Whelan, "Session [RFC2974] Handley, M., Perkins, C., and E. Whelan, "Session
Announcement Protocol", RFC 2974, October 2000. Announcement Protocol", RFC 2974, October 2000.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
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