draft-ietf-mmusic-media-loopback-24.txt   draft-ietf-mmusic-media-loopback-25.txt 
MMUSIC Working Group H. Kaplan (ed.) MMUSIC Working Group H. Kaplan (ed.)
Internet-Draft Acme Packet Internet-Draft Acme Packet
Intended status: Proposed Standard K. Hedayat Intended status: Proposed Standard K. Hedayat
Expires: May 6, 2013 EXFO Expires: June 17, 2013 EXFO
N. Venna N. Venna
Saperix Saperix
P. Jones P. Jones
Cisco Systems, Inc. Cisco Systems, Inc.
N. Stratton N. Stratton
BlinkMind, Inc. BlinkMind, Inc.
November 6, 2012 December 17, 2012
An Extension to the Session Description Protocol (SDP) An Extension to the Session Description Protocol (SDP)
and Real-time Transport Protocol (RTP) for Media Loopback and Real-time Transport Protocol (RTP) for Media Loopback
draft-ietf-mmusic-media-loopback-24 draft-ietf-mmusic-media-loopback-25
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with This Internet-Draft is submitted to IETF in full conformance with
the provisions of BCP 78 and BCP 79. the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
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documents at any time. It is inappropriate to use Internet-Drafts documents at any time. It is inappropriate to use Internet-Drafts
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progress". progress".
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on May 6, 2013. This Internet-Draft will expire on June 17, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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respect to this document. Code Components extracted from this respect to this document. Code Components extracted from this
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10, 2008. The person(s) controlling the copyright in some of this 10, 2008. The person(s) controlling the copyright in some of this
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except to format it for publication as an RFC or to translate it except to format it for publication as an RFC or to translate it
into languages other than English. into languages other than English.
Abstract Abstract
The wide deployment of Voice over IP (VoIP), Text and Video over IP The wide deployment of Voice over IP (VoIP), Text and Video over IP
services has introduced new challenges in managing and maintaining services has introduced new challenges in managing and maintaining
real-time voice/text/video quality, reliability, and overall real-time voice/text/video quality, reliability, and overall
performance. In particular, media delivery is an area that needs performance. In particular, media delivery is an area that needs
attention. One method of meeting these challenges is monitoring attention. One method of meeting these challenges is monitoring
the media delivery performance by looping media back to the the media delivery performance by looping media back to the
transmitter. This is typically referred to as "active monitoring" transmitter. This is typically referred to as "active monitoring"
of services. Media loopback is especially popular in ensuring the of services. Media loopback is especially popular in ensuring the
quality of transport to the edge of a given VoIP, Real-time Text or quality of transport to the edge of a given VoIP, Real-time Text or
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media, short of running 'ping' and 'traceroute' to the edge, media, short of running 'ping' and 'traceroute' to the edge,
administrators are left without the necessary tools to actively administrators are left without the necessary tools to actively
monitor, manage, and diagnose quality issues with their service. monitor, manage, and diagnose quality issues with their service.
The extension defined herein adds new SDP media types and The extension defined herein adds new SDP media types and
attributes, which enable establishment of media sessions where the attributes, which enable establishment of media sessions where the
media is looped back to the transmitter. Such media sessions will media is looped back to the transmitter. Such media sessions will
serve as monitoring and troubleshooting tools by providing the serve as monitoring and troubleshooting tools by providing the
means for measurement of more advanced VoIP, Real-time Text and means for measurement of more advanced VoIP, Real-time Text and
Video over IP performance metrics. Video over IP performance metrics.
Table of Contents Table of Contents
1. Introduction..................................................3 1. Introduction..................................................3
1.1 Use Cases Supported.......................................4 1.1 Use Cases Supported.......................................4
2. Terminology...................................................6 2. Terminology...................................................6
3. Overview of Operation.........................................6 3. Overview of Operation.........................................6
3.1 SDP Offerer Behavior......................................6 3.1 SDP Offerer Behavior......................................6
3.2 SDP Answerer Behavior.....................................7 3.2 SDP Answerer Behavior.....................................7
4. New SDP Attributes............................................7 4. New SDP Attributes............................................7
4.1 Loopback Type Attribute...................................7 4.1 Loopback Type Attribute...................................8
4.2 Loopback Role Attributes: loopback-source and loopback- 4.2 Loopback Role Attributes: loopback-source and loopback-
mirror........................................................8 mirror........................................................9
5. Rules for Generating the SDP offer/answer.....................9 5. Rules for Generating the SDP offer/answer....................10
5.1 Generating the SDP Offer for Loopback Session.............9 5.1 Generating the SDP Offer for Loopback Session............10
5.2 Generating the SDP Answer for Loopback Session...........10 5.2 Generating the SDP Answer for Loopback Session...........11
5.3 Offerer Processing of the SDP Answer.....................12 5.3 Offerer Processing of the SDP Answer.....................13
5.4 Modifying the Session....................................12 5.4 Modifying the Session....................................13
5.5 Establishing Sessions Between Entities Behind NAT........12 5.5 Establishing Sessions Between Entities Behind NAT........13
6. RTP Requirements.............................................13 6. RTP Requirements.............................................13
7. Payload formats for Packet loopback..........................13 7. Payload formats for Packet loopback..........................14
7.1 Encapsulated Payload format..............................14 7.1 Encapsulated Payload format..............................14
7.2 Direct loopback RTP payload format.......................16 7.2 Direct loopback RTP payload format.......................17
8. SRTP Behavior................................................17 8. SRTP Behavior................................................18
9. RTCP Requirements............................................18 9. RTCP Requirements............................................18
10. Congestion Control..........................................18 10. Congestion Control..........................................19
11. Examples....................................................18 11. Examples....................................................19
11.1 Offer for specific media loopback type..................18 11.1 Offer for specific media loopback type..................19
11.2 Offer for choice of media loopback type.................19 11.2 Offer for choice of media loopback type.................20
11.3 Answerer rejecting loopback media.......................20 11.3 Answerer rejecting loopback media.......................21
12. Security Considerations.....................................21 12. Security Considerations.....................................21
13. Implementation Considerations...............................22 13. Implementation Considerations...............................22
14. IANA Considerations.........................................22 14. IANA Considerations.........................................23
14.1 SDP Attributes..........................................22 14.1 SDP Attributes..........................................23
14.2 Media Types.............................................23 14.2 Media Types.............................................24
15. Acknowledgements............................................31 15. Acknowledgements............................................32
16. Normative References........................................31 16. Normative References........................................32
17. Informative References......................................32 17. Informative References......................................33
1. Introduction 1. Introduction
The overall quality, reliability, and performance of VoIP, The overall quality, reliability, and performance of VoIP,
Real-time Text and Video over IP services rely on the performance Real-time Text and Video over IP services rely on the performance
and quality of the media path. In order to assure the quality of and quality of the media path. In order to assure the quality of
the delivered media there is a need to monitor the performance of the delivered media there is a need to monitor the performance of
the media transport. One method of monitoring and managing the the media transport. One method of monitoring and managing the
overall quality of real-time VoIP, Text and Video over IP Services overall quality of real-time VoIP, Text and Video over IP Services
is through monitoring the quality of the media in an active is through monitoring the quality of the media in an active
session. This type of "active monitoring" of services is a method session. This type of "active monitoring" of services is a method
of proactively managing the performance and quality of VoIP based of proactively managing the performance and quality of VoIP based
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format: whatever is indicated for normal media, since the "looping" format: whatever is indicated for normal media, since the "looping"
is performed at the codec level. When packet-level looping is is performed at the codec level. When packet-level looping is
performed, however, the mirror can either send back RTP in an performed, however, the mirror can either send back RTP in an
encapsulated format or direct-loopback format. The rest of this encapsulated format or direct-loopback format. The rest of this
document describes these loopback types, roles, and encoding document describes these loopback types, roles, and encoding
formats, and the SDP offer/answer rules for indicating them. formats, and the SDP offer/answer rules for indicating them.
3.1 SDP Offerer Behavior 3.1 SDP Offerer Behavior
An SDP offerer compliant to this specification and attempting to An SDP offerer compliant to this specification and attempting to
establish a media session with media loopback MUST include establish a media session with media loopback will include
"loopback" media attributes for each individual media description "loopback" media attributes for each individual media description
in the offer message. The offerer will look for the "loopback" in the offer message that it wishes to have looped back. Note that
media attributes in the media description(s) of the response from the offerer may choose to only request loop back for some media
the answer for confirmation that the request is accepted. descriptions/streams but not others. For example it might wish to
request loopback for a video stream but not audio, or vice-versa.
The offerer will look for the "loopback" media attributes in the
media description(s) of the response from the SDP answer for
confirmation that the request is accepted.
3.2 SDP Answerer Behavior 3.2 SDP Answerer Behavior
If an SDP answerer compliant to this specification receives an If an SDP answerer compliant to this specification receives an
offer containing media descriptions with the "loopback" media offer containing media descriptions with the "loopback" media
attributes and it wants to accept such for the purposes of media- attributes and it wants to accept such for the purposes of media-
loopback, MUST acknowledge the request by including the received loopback, it MUST acknowledge the request by including the received
"loopback" media attributes for each media description in its "loopback" media attribute(s) for each media description in its
answer. If the answerer does not want to do loopback or wants to answer that it accepts looping back for. If the answerer does not
reject the "loopback" request for specific media descriptions, it want to do loopback or wants to reject the "loopback" request for
MUST do so as defined in this section. specific media descriptions, it MUST do so as defined in this
section.
An answerer can reject an offered stream (either with loopback- An answerer can reject an offered stream (either with loopback-
source or loopback-mirror) if the loopback-type is not specified, source or loopback-mirror) if the loopback-type is not specified,
the specified loopback-type is not supported, or the endpoint the specified loopback-type is not supported, or the endpoint
cannot honor the offer for any other reason. The loopback request cannot honor the offer for any other reason. The loopback request
is rejected by setting the stream's media port number to zero in is rejected by setting the stream's media port number to zero in
the answer as defined in RFC 3264 [RFC3264], or by rejecting the the answer as defined in RFC 3264 [RFC3264], or by rejecting the
entire offer (i.e., by rejecting the session request entirely). entire offer (i.e., by rejecting the session request entirely).
Note that an answerer that is not compliant to this specification Note that an answerer that is not compliant to this specification
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