Network Working Group Q. Wu
Internet-Draft F. Xia
Intended status: Standards Track R. Even
Expires: March 29, 2012 Huawei
September 26, 2011
RTCP Extension for Third-party Loss Report
draft-ietf-avtcore-feedback-supression-rtp-07
Abstract
In a large RTP session using the RTCP feedback mechanism defined in
RFC 4585, a feedback target may experience transient overload if some
event causes a large number of receivers to send feedback at once.
This overload is usually avoided by ensuring that feedback reports
are forwarded to all receivers, allowing them to avoid sending
duplicate feedback reports. However, there are cases where it is not
recommended to forward feedback reports, and this may allow feedback
implosion. This memo discusses these cases and defines a new RTCP
third-party loss report that can be used to inform receivers that the
network is aware of some loss event, allowing them to suppress
feedback. Associated SDP signalling is also defined.
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 March 29, 2012.
Copyright Notice
Copyright (c) 2011 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
Wu, et al. Expires March 29, 2012 [Page 1]
Internet-Draft Third Party Loss Report September 2011
(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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 4
4. Format of RTCP Feedback Messages . . . . . . . . . . . . . . . 5
4.1. Transport Layer Feedback: Third-party Loss Report . . . . 5
4.2. Payload Specific Feedback: Third-party Loss Report . . . . 6
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Example Use Cases . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Source Specific Multicast (SSM) use case . . . . . . . . . 8
6.2. Unicast based Rapid Acquisition of Multicast Stream
(RAMS) use case . . . . . . . . . . . . . . . . . . . . . 9
6.3. RTP transport translator use case . . . . . . . . . . . . 9
6.4. Multipoint Control Unit (MCU) use case . . . . . . . . . . 9
6.5. Mixer use Case . . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Consideration . . . . . . . . . . . . . . . . . . . . . . 11
9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 12
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . . 13
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 13
A.1. draft-ietf-avtcore-feedback-suppression-rtp-01 . . . . . . 13
A.2. draft-ietf-avtcore-feedback-suppression-rtp-02 . . . . . . 14
A.3. draft-ietf-avtcore-feedback-suppression-rtp-03 . . . . . . 14
A.4. draft-ietf-avtcore-feedback-suppression-rtp-04 . . . . . . 14
A.5. draft-ietf-avtcore-feedback-suppression-rtp-05 . . . . . . 15
A.6. draft-ietf-avtcore-feedback-suppression-rtp-06 . . . . . . 15
A.7. draft-ietf-avtcore-feedback-suppression-rtp-07 . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
Wu, et al. Expires March 29, 2012 [Page 2]
Internet-Draft Third Party Loss Report September 2011
1. Introduction
RTCP feedback messages [RFC4585] allow the receivers in an RTP
session to report events and ask for action from the media source (or
a delegated feedback target when using unicast RTCP feedback with SSM
[RFC5760]). There are cases where multiple receivers may initiate
the same, or an equivalent message towards the same media source.
When the receiver count is large, this behavior may cause transient
overload of the media source, the network or both. This is known as
a "feedback storm" or a "NACK storm". One common cause of such a
feedback storm is receivers utilizing RTP retransmission [RFC4588] as
a packet loss recovery technique based, sending feedback using RTCP
NACK messages [RFC4585] without proper dithering of the
retransmission requests (e.g., implementing the RFC 4585 dithering
rules or sending NACKs to a middlebox that doesn't redistribute them
to other receivers).
Another use case involves video Fast Update requests. A storm of
these feedback messages can occur in conversational multimedia
scenarios like multipoint video switching conference [RFC4587]. In
this scenario, the receiver may lose synchronization with the video
stream when speaker is changed in the middle of session. Poorly
designed receivers that blindly issue fast update requests (i.e.,
Full Intra Request (FIR) described in [RFC5104]), can cause an
implosion of FIR requests from receivers to the same media source.
RTCP feedback storms may cause short term overload, and in extreme
cases to pose a possible risk of increasing network congestion on the
control channel (e.g. RTCP feedback), the data channel, or both. It
is therefore desirable to provide a way of suppressing unneeded
feedback.
One approach to this, suggested in [DVB-IPTV], involves sending a
NACK message to the other clients (or receiver) in the same group as
the sender of NACK. However NACK is defined as a receiver report
sent from a receiver observing a packet loss, therefore it only
inform others that sender of NACK detected loss while the case the
sender of the feedback has received reports that the indicated
packets were lost is not covered. This document specifies a new
third-party loss report for this function. It supplements the
existing the use of RTCP NACK packet and further is more precise in
the uses where the network is active to suppress feedback. It tells
receivers explicitly that feedback for a particular packet or frame
loss is not needed for a period of time and can provide an early
indication before the receiver reacts to the loss and invokes its
packet loss repair machinery. Section 6 provides some examples of
when to send the Third Party Loss Report message. Section 6 provides
some examples of when to send the Third Party Loss Report message.
Wu, et al. Expires March 29, 2012 [Page 3]
Internet-Draft Third Party Loss Report September 2011
2. Terminology
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Protocol Overview
This document extends the RTCP feedback messages defined in the
Audio-Visual Profile with feedback (RTP/AVPF) [RFC4585] defining a
Third Party Loss Report message. The Third Party Loss Report message
can be used by the intermediaries to inform the receiver that the
sender of the Third Party Loss Report has received reports that the
indicated packets were lost, and asks the receiver not to send
feedback to it regarding these packets.
RTCP Third Party Loss Report follows the similar format of message
type as RTCP NACK or Full Intra Request Command. However, the Third
Party Loss Report is defined as an indication that the sender of the
feedback has received reports that the indicated packets were lost,
while NACK [RFC4585] just indicates that the sender of the NACK
observed that these packets were lost. The Third Party Loss Report
message is generated by a RTP system that has not seen the actual
packet loss and sent following the same timing rule as sending NACK
defined in [RFC4585], e.g., The TPLR message may be sent in a regular
full compound RTCP packet or in an early RTCP packet, as per AVPF.
RTP Systems in the network that receive a Third Party Loss Report
SHOULD NOT initiate their own additional Third Party Loss Report
messages for the same packet sequence numbers. They should simply
forward the Third Party Loss Report message received from upstream
direction, additionally, they may generate their own Third Party Loss
Report that reports a set of the losses they see, which are different
from ones reported in the Third Party Loss report they received. The
Third Party Loss Report does not have the retransmission request
[RFC4588] semantics.
When a receiver gets a Third Party Loss Report message, it should
start a timer for this message and refrain from sending a feedback
request (e.g., NACK or FIR) for the missing packets reported in the
message during the lifetime of the timer. The timer value shall be
based on the observed round-trip time. A receiver should compute an
estimate of the round-trip time (RTT) to the sender of TPLR from RTCP
report round-trip time if available, or its reception time of the
reflected RTCP FB message (e.g.,NACK), or any other means.
To increase the robustness to the loss of a TPLR or of a transmission
packet, a receiver is allowed to receive additional TPLR for the same
Wu, et al. Expires March 29, 2012 [Page 4]
Internet-Draft Third Party Loss Report September 2011
packet. In the case the first TPLR is lost and the additional TPLR
arrives at the receiver, the receiver should immediately refresh the
timer. When the timer for this message expires and there is no
retransmitted packet or a new Third Party Loss Report message, the
receiver should take its normal behavior as if there is no current
retransmission suppression.
A receiver may still have sent a Feedback message according to the
RTP/AVPF scheduling algorithm of [RFC4585] before receiving a Third
Party Loss Report message, but further feedback messages for those
sequence numbers will be suppressed by this technique for a certain
period of time. Nodes that do not understand the Third Party Loss
Report message will ignore it, and might therefore still send
feedback according to the AVPF scheduling algorithm of [RFC4585].
The media source or intermediate nodes cannot assume that the use of
a Third Party Loss Report message actually reduces the amount of
feedback it receives.
Since Third Party Loss Report interacts strongly with repair timing,
it has to work together with feedback to not adversely impact the
repair of lost source packets. In order not to incur a lot of NACK
requests due to additional TPLR described above, it is recommended
that the RTP system sending TPLR should be implemented more closer to
the source. Also when the loss was detected and repair initiated
much closer to the source, the delay for the receiver to recover from
packet loss can be reduced through the combination of intermediary
feedback to the source and Third Party Loss Report downstream.
4. Format of RTCP Feedback Messages
This document registers two new RTCP Feedback messages for Third
Party Loss Report. Applications that are employing one or more loss-
repair methods MAY use the Third Party Loss Report together with
their existing loss-repair methods either for every packet they
expect to receive, or for an application-specific subset of the RTP
packets in a session. In other words, receivers MAY ignore Third
Party Loss Report messages, but SHOULD react to them unless they have
good reason to still send feedback messages despite having been
requested to suppress them.
4.1. Transport Layer Feedback: Third-party Loss Report
This Third Party Loss Report message is an extension to the RTCP
Transport Layer Feedback Report and identified by RTCP packet type
value PT=RTPFB and FMT=TBD.
Within the common packet header for feedback messages (as defined in
Wu, et al. Expires March 29, 2012 [Page 5]
Internet-Draft Third Party Loss Report September 2011
section 6.1 of [RFC4585]), the "SSRC of packet sender" field
indicates the source of the request, and the "SSRC of media source"
denotes the media sender.
The FCI field MUST contain one or more entries of transport layer
third party loss Early Indication (TLLEI). Each entry applies to the
same media source identified by the SSRC contained in the SSRC of
media source field of Feedback header.
The Feedback Control Information (FCI) for TLLEI uses the similar
format of message Types defined in the section 6.2.1 of [RFC4585].
The format is shown in Figure 1.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PID | BLP |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Message Format for the Third Party Loss Report
Packet ID (PID): 16 bits
The PID field is used to specify a lost packet. The PID field
refers to the RTP sequence number of the lost packet.
bitmask of proceeding lost packets (BLP): 16 bits
The BLP allows for reporting losses of any of the 16 RTP packets
immediately following the RTP packet indicated by the PID. The
BLP's definition is identical to that given in [RFC4585].
4.2. Payload Specific Feedback: Third-party Loss Report
This message is an extension to the RTCP Payload Specific Feedback
report and identified by RTCP packet type value PT=PSFB and FMT=TBD,
which is used to suppress FIR [RFC5104]or PLI [RFC4585].
Within the common packet header for feedback messages (as defined in
section 6.1 of [RFC4585]), the "SSRC of packet sender" field
indicates the source of the request, and the "SSRC of media source"
is not used and SHALL be set to 0. The SSRCs of the media senders to
which this message applies are in the corresponding FCI entries.
The FCI field MUST contain a Payload Specific Third Party Loss Early
Indication (PSLEI) entry. Each entry applies to a different media
Source that is requested to send a decoder refresh point or that is
Wu, et al. Expires March 29, 2012 [Page 6]
Internet-Draft Third Party Loss Report September 2011
indicated that it lost synchronization with the video stream,
identified by its SSRC.
The Feedback Control Information (FCI) for PSLEI uses the similar
format of message Types defined in the section 4.3.1.1 of [RFC5104].
The format is shown in Figure 2.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seq nr. | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Message Format for the Third Party Loss Report
SSRC (32 bits):
The SSRC value of the media source that is requested to send a
decoder refresh point or that is indicated that it lost
synchronization with the video stream.
Seq nr:8bits Command sequence number. It is used by the Command
receiver to check if the Command is repeated. The sequence number
space is unique for each pairing of the SSRC of command sender and
the SSRC of the command receiver. The sequence number SHALL
increase by 1 modulo 256 for each new Command. A repetition SHALL
NOT increase the sequence number. The initial value is arbitrary.
Reserved: 24 bits
All bits SHALL be set to 0 by the media source and SHALL be
ignored on reception.
5. SDP Signaling
A new feedback value "tplr" needs to be defined for the Third Party
Loss Report message to be used with Session Description Protocol
(SDP) [RFC4566] using the Augmented Backus-Naur Form (ABNF)
[RFC4585].
The "tplr" feedback value SHOULD be used with parameters that
indicate the third party loss supported. In this document, we define
two such parameter, namely:
Wu, et al. Expires March 29, 2012 [Page 7]
Internet-Draft Third Party Loss Report September 2011
o "tllei" denotes support of transport layer third party loss early
indication.
o "pslei" denotes support of payload specific third party loss early
indication.
In the ABNF for rtcp-fb-val defined in [RFC4585], there is a
placeholder called rtcp-fb-id to define new feedback types. "tplr" is
defined as a new feedback type in this document, and the ABNF for the
parameters for tplr is defined here (please refer to section 4.2 of
[RFC4585] for complete ABNF syntax).
rtcp-fb-val =/ "tplr" rtcp-fb-tplr-param
rtcp-fb-tplr-param = SP "tllei";transport layer third party loss early indication
/ SP "pslei";payload specific third party loss early indication
/ SP token [SP byte-string]
; for future commands/indications
byte-string = <as defined in section 4.2 of [RFC4585] >
Refer to Section 4.2 of [RFC4585] for a detailed description and the
full syntax of the "rtcp-fb" attribute.
6. Example Use Cases
The operation of feedback suppression is similar for all types of RTP
sessions and topologies [RFC5117], however the exact messages used
and the scenarios in which suppression is employed differ for various
use cases. The following sections outline some of the intended use
cases for using the Third Party Loss Report for feedback suppression
and give an overview of the particular mechanisms.
6.1. Source Specific Multicast (SSM) use case
In SSM RTP sessions as described in [RFC5760], one or more Media
Sources send RTP packets to a Distribution Source. The Distribution
Source relays the RTP packets to the receivers using a source-
specific multicast group.
As outlined in the [RFC5760], there are two Unicast Feedback models
that may be used for reporting, the Simple Feedback model and the
Distribution Source Feedback Summary Model. In the simple Feedback
Model, there's no need for distribution source to create the Third
Party Loss Report, instead, NACKs are reflected by the distribution
source to the other Receivers. However in the Distribution Source
Feedback Summary model, the distribution source will not redistribute
the NACK for some reason(e.g., to prevent revealing the identity or
existence of a system sending NACK)and may send a Third Party Loss
Wu, et al. Expires March 29, 2012 [Page 8]
Internet-Draft Third Party Loss Report September 2011
Report to the systems that were unable to receive the NACK, and won't
receive the NACK via other means. since the summary feedback does not
mandate the forwarding of NACK downstream. The Third Party Loss
Report can be generated at the distribution source when downstream
loss is told (e.g., downstream loss report is received), which
indicates to the receivers that they should not transmit feedback
messages for the same loss event for a certain time. Therefore the
distribution source in the feedback summary model can be reasonably
certain that it will help the situation by sending this Third Party
Loss Report message to all the relevant receivers impacted by the
packet loss.
6.2. Unicast based Rapid Acquisition of Multicast Stream (RAMS) use
case
The typical RAMS architecture [RFC6285] may have several Burst/
Retransmission Sources(BRS) behind the multicast source (MS) placed
at the same level. These BRSes will receive the primary multicast
RTP stream from the media source and cache most recent packets after
joining multicast session. If packet loss happens at the upstream of
all the BRSs or the downstream of one or more BRSes. one of the BRSes
or all the BRSes may send a NACK or TPLR message to the DS, where the
SSRC in this NACK or TPLR message is the one of the BRS. The DS
forwards/reflects this message down on the primary SSM. The details
on how DS deal with this message is specified in
[RETRANSMISSION-FOR-SSM].
6.3. RTP transport translator use case
A Transport Translator (Topo-Trn-Translator), as defined in [RFC5117]
is typically forwarding the RTP and RTCP traffic between RTP clients,
for example converting between multicast and unicast for domains that
do not support multicast. The translator acting as quality
monitoring [Monarch] may suffer a loss of important video packets.
In this case, the translator may trigger repair by the media sender
and at the same time,use it's own SSRC as packet sender SSRC to
create a new Third Party Loss Report message and send it to the
receivers that is not aware of packet loss.
6.4. Multipoint Control Unit (MCU) use case
When the speaker is changed in a voice-activated multipoint video
switching conference [RFC4587], an RTP mixer can be used to select
the available input streams and forward them to each participants.
If the MCU is doing a blind switch without waiting for a
synchronization point on the new stream it can send a FIR to the new
video source. In this case the MCU should send a FIR suppression
message to the new receivers. e.g.,when the RTP Mixer starts to
Wu, et al. Expires March 29, 2012 [Page 9]
Internet-Draft Third Party Loss Report September 2011
receive FIR from some participants it can suppress the remaining
session participants from sending FIR by sending out a Third party
Loss report message.
6.5. Mixer use Case
A Mixer, in accordance with [RFC5117], aggregates multiple RTP
streams from other session participants and generates a new RTP
stream sent to the session participants. In some cases, the video
frames may get badly screwed up between media source and the mixer.
In such case, the mixer need to check if the packet loss will result
in PLI or FIR transmissions from most of the group by analyzing the
received video. If so the mixer initiates FIR or PLI towards the
media source on behalf of all the session participants and send out a
Third party Loss report message to these session participants that
may or are expected to send a PLI or FIR Another possible way for
mixer to deal with, is when the mixer starts to receive FIR or PLI
from some participants and like to suppress the remaining session
participants from sending FIR or PLI by sending out a Third party
Loss report message.
7. Security Considerations
The defined messages have certain properties that have security
implications. These must be addressed and taken into account by
users of this protocol.
Spoofed or maliciously created feedback messages of the type defined
in this specification can have the following implications:
Sending the spurious Third Party Loss Report (e.g., the Third Party
Loss Report with the wrong sequence number of lost packet) that makes
missing RTP packets can not be compensated.
To prevent these attacks, there is a need to apply authentication and
integrity protection of the feedback messages. This can be
accomplished against threats external to the current RTP session
using the RTP profile that combines Secure RTP [RFC3711] and AVPF
into SAVPF [RFC5124].
Note that middleboxes that are not visible at the RTP layer that wish
to send the Third Party Loss Reports on behalf of the media source
can only do so if they spoof the SSRC of the media source. This is
difficult in case SRTP is in use. If the middlebox is visible at the
RTP layer, this is not an issue, provided the middlebox is part of
the security context for the session.
Wu, et al. Expires March 29, 2012 [Page 10]
Internet-Draft Third Party Loss Report September 2011
Also note that endpoints that receive a Third Party Loss Report would
be well-advised to ignore it, unless the security is in place to
authenticate the sender of the Third Party Loss Report. Accepting
Third Party Loss Report from un-authenticated sender can lead to a
denial of service attack, where the endpoint accepts poor quality
media that could be repaired.
8. IANA Consideration
The new value "TPLR" has been registered with IANA in the "rtcp-fb"
Attribute Values registry located at the time of publication at:
http://www.iana.org/assignments/sdp-parameters
Value name: tplr
Long Name: Third Party Loss Reports
Reference: This document
A new registry " Third Party Loss Report Messages" has been created
to hold "tplr" parameters located at time of publication at:
http://www.iana.org/assignments/sdp-parameters
New registration in this registry follows the "Specification
required" policy as defined by [RFC2434]. In addition, they are
required to indicate any additional RTCP feedback types, such as
"nack" and "ack".
The following values have been registered as FMT values in the "FMT
Values for RTPFB Payload Types" registry located at the time of
publication at: http://www.iana.org/assignments/rtp-parameters
RTPFB range
Name Long Name Value Reference
-------------- --------------------------------- ----- ---------
TLLEI Transport Layer Third Party X [RFCXXXX]
Loss Early Indication
The following values have been registered as FMT values in the "FMT
Values for PSFB Payload Types" registry located at the time of
publication at: http://www.iana.org/assignments/rtp-parameters
PSFB range
Name Long Name Value Reference
-------------- --------------------------------- ----- ---------
PSLEI Payload Specific Third Party X [RFCXXXX]
Loss Early Indication
Wu, et al. Expires March 29, 2012 [Page 11]
Internet-Draft Third Party Loss Report September 2011
9. Acknowledgement
The authors would like to thank David R Oran, Magnus Westerlund,
Colin Perkins, Ali C. Begen, Tom VAN CAENEGEM, Ingemar Johansson S,
Bill Ver Steeg, Jonathan Lennox, WeeSan Lee for their valuable
comments and suggestions on this document.
10. References
10.1. Normative References
[RFC5760] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control
Protocol (RTCP) Extensions for Single-Source Multicast
Sessions with Unicast Feedback", RFC 5760, February 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
July 2006.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
July 2006.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
"Codec Control Messages in the RTP Audio-Visual Profile
with Feedback (AVPF)", RFC 5104, February 2008.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback
Wu, et al. Expires March 29, 2012 [Page 12]
Internet-Draft Third Party Loss Report September 2011
(RTP/SAVPF)", RFC 5124, February 2008.
10.2. Informative References
[RFC5740] Adamson, B., Bormann, C., Handley, M., and J. Macker,
"NACK-Oriented Reliable Multicast (NORM) Transport
Protocol", November 2009.
[DVB-IPTV]
ETSI Standard, "Digital Video Broadcasting(DVB); Transport
of MPEG-2 TS Based DVB Services over IP Based Networks",
ETSI TS 102 034, V1.4.1 , August 2009.
[RFC6285] Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast-
Based Rapid Acquisition of Multicast RTP Sessions",
June 2011.
[Monarch] Wu, Q., Hunt, G., and P. Arden, "Monitoring Architectures
for RTP", June 2011.
[RETRANSMISSION-FOR-SSM]
Caenegem, T., Steeg, B., and A. Begen, "Retransmission for
Source-Specific Multicast (SSM) Sessions", May 2011.
[RFC5117] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117,
January 2008.
[RFC4587] Even, R., "RTP Payload Format for H.261 Video Streams",
RFC 4587, August 2006.
Appendix A. Change Log
Note to the RFC-Editor: please remove this section prior to
publication as an RFC.
A.1. draft-ietf-avtcore-feedback-suppression-rtp-01
The following are the major changes compared to previous version:
o Remove the merge report from SSM use case and additional text to
address report merging issue.
o Revise section 3 and section 6 to address FEC packet dealing issue
and Leave how to repair packet loss beyond the scope.
Wu, et al. Expires March 29, 2012 [Page 13]
Internet-Draft Third Party Loss Report September 2011
o Modify the SSM use case and RAMS use case to focus on uses.
o Other Editorial changes.
A.2. draft-ietf-avtcore-feedback-suppression-rtp-02
The following are the major changes compared to previous version:
o In Section 4.1, fix typo: Section 4.3.1.1 of section [RFC5104]->
section 6.2.1 of [RFC4585].
o In Section 3: Clarify how to deal with downstream loss using Third
party loss report and upstream loss using NACK.
o Update title and abstract to focus on third party loss report.
o In Section 6.1: Update this section to explain how third party
loss report is used to deal with downstream loss.
o In section 6.1.2: Update this section to explain how third party
loss report is used to deal with downstream loss.
o In section 6.2: Rephrase the text to discuss how BRS deal with the
third party loss report.
A.3. draft-ietf-avtcore-feedback-suppression-rtp-03
The following are the major changes compared to previous version:
o In Appendix A, fix typo: Appendix A. Appendix A. -> Appendix A.
o Update abstract to clarify when third-party loss reports should be
sent instead of NACKs.
o Update section 3 Paragraph 2 to differentiate when a third-party
loss report should be used compared to a NACK.
o Update section 3 Paragraph 3 to explain when media source to send
a third-party loss.
o Move specific rules for section 6.1.1 and section 6.1.2 to section
6.1 as generic rules and delete section 6.1.1.
A.4. draft-ietf-avtcore-feedback-suppression-rtp-04
The following are the major changes compared to previous version:
Wu, et al. Expires March 29, 2012 [Page 14]
Internet-Draft Third Party Loss Report September 2011
o Reference Update.
o Clarify the use of the third party loss report in section 3 and
section 6.1.1.
A.5. draft-ietf-avtcore-feedback-suppression-rtp-05
The following are the major changes compared to previous version:
o Remove 3rd and 4th paragraphs of section 6.1 and replaced them
with 2nd and 3rd paragraphs of section 3.
o Remove section 6.1.1.1.
o Revise the last paragraph of section 1 to clarify the rationale of
using new message.
o Update RTP transport translator case in section 6.3 to correct the
use of the third party loss report.
o Update MCU case in section 6.4 to correct the use of the third
party loss report.
o Revise SSM use case to address multiple DS issue.
o References Update.
o Move one rationale on preventing sending unicast NACK in
introduction section to SSM case section.
o Other Editorial changes to section 6.1, 6.1.1, 6.2.
A.6. draft-ietf-avtcore-feedback-suppression-rtp-06
The following are the major changes compared to previous version:
o A few Editorial changes to the whole document.
A.7. draft-ietf-avtcore-feedback-suppression-rtp-07
The following are the major changes compared to previous version:
o Restructuring the protocol overview section to clarify the round
trip time calculation and receiver behavior to the additional
TPLR.
o Restructuring the SSM use case section to focus on the use of
TPLR.
Wu, et al. Expires March 29, 2012 [Page 15]
Internet-Draft Third Party Loss Report September 2011
o Editorial changes to the abstract, introduction, message format,
use cases and IANA sections.
o References update
Authors' Addresses
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
Frank Xia
Huawei
1700 Alma Dr. Suite 500
Plano, TX 75075
USA
Phone: +1 972-509-5599
Email: xiayangsong@huawei.com
Roni Even
Huawei
14 David Hamelech
Tel Aviv 64953
Israel
Email: even.roni@huawei.com
Wu, et al. Expires March 29, 2012 [Page 16]