Network Working Group Q. Wu
Internet-Draft F. Xia
Intended status: Standards Track R. Even
Expires: June 1, 2012 Huawei
November 29, 2011
RTCP Extension for Third-party Loss Report
draft-ietf-avtcore-feedback-supression-rtp-09
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
feedback target is aware of some loss event, allowing them to
suppress feedback. Associated SDP signalling is also defined.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 1, 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
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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 . . . . . . . . . . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . . 12
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
A.8. draft-ietf-avtcore-feedback-suppression-rtp-08 . . . . . . 16
A.9. draft-ietf-avtcore-feedback-suppression-rtp-09 . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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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, sending feedback using RTCP NACK
messages [RFC4585] without proper dithering of the retransmission
requests (e.g., not 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 where
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.
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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
(TPLR) message is generated by a RTP system that may not seen the
actual packet loss. It is sent following the same timing rule as
sending NACK defined in [RFC4585]. The TPLR feedback message may be
sent in a regular full compound RTCP packet or in an early RTCP
packet, as per the RTP/AVPF rules. RTP Systems in the network that
receive a Third Party Loss Report SHOULD NOT send 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
follow the rules for NACK suppression in RFC 4585 and refrain from
sending a feedback request (e.g., NACK or FIR) for the missing
packets reported in the message,which is dealt with in the same way
as receiving NACK.
To increase the robustness to the loss of a TPLR or of a transmission
RTP data packet, TPLR or the RTP packet for the same missing Packet
may be retransmitted when RTP systems are aware that the same packet
loss occurs again. If the additional TPLR arrives at receiver, the
receiver should deal with the additional TPLR in the same way as
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receiving the first TPLR for the same packet and no additional
behavior for receiver is required. When the retransmitted packet is
received by the receiver,it should take its normal behavior as if
there is no current feedback 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 SHOULD be suppressed for a period of time after
receiving the TPLR. 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 be certain 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 media source. When the loss was detected and repair initiated
much closer to the media 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
section 6.1 of [RFC4585]), the "SSRC of packet sender" field
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indicates the source of the request, and the "SSRC of media source"
denotes the media sender of the flow for which the indicated losses
are being suppressed .
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 length of the TLLEI
feedback message MUST be set to 2+1*N, where N is the number of FCI
entries.
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: Syntax of an FCI Entry in the TLLEI Feedback Message
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 Feedback Control Information (FCI) for a Payload Specific Third
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Party Loss Early Indication (PSLEI) consists one or more FCI entries.
Each entry applies to a different media Source, identified by its
SSRC. the content of which is depicted in Figure 2. The length of
the PSLEI feedback message MUST be set to 2+1*N, where N is the
number of FCI entries.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Syntax of an FCI Entry in the PSLEI Feedback Message
Synchronization source (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.
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:
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 [RFC5234] 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).
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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
token = <as defined in section 9 of [RFC4566]>
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
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
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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 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 BRS that is sending the message.
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 from multicast to unicast for domains that do
not support multicast. The translator may suffer a loss of important
video packets. In this case, the translator may forward TPLR message
received from upstream in the same way as forwarding other RTCP
traffic. If the translator acting as quality monitor [Monarch]is
aware of packet loss, it may use the SSRC of monitor as packet sender
SSRC to create NACK 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
receive FIR from some participants it can suppress the remaining
session participants from sending FIR by sending out a Third party
Loss report message.
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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 may initiate 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. Alternatively, 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 forwarding the FIR/PLI from one session participant to others.
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
causes missing RTP packets to not be repaired in a timely fashion.
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.
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
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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 [RFC5226]. In addition, they are
required to indicate any additional RTCP feedback types, such as
"nack" and "ack".
The following value have been registered as one FMT value 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 TBA1 [RFCXXXX]
Loss Early Indication
The following value have been registered as one FMT value 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 TBA2 [RFCXXXX]
Loss Early Indication
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
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comments and suggestions on this document.
10. References
10.1. Normative References
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[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.
[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.
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.
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[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.
[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.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, 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.
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.
o Modify the SSM use case and RAMS use case to focus on uses.
o Other Editorial changes.
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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:
o Reference Update.
o Clarify the use of the third party loss report in section 3 and
section 6.1.1.
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Internet-Draft Third Party Loss Report November 2011
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.
o Editorial changes to the abstract, introduction, message format,
use cases and IANA sections.
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o References update
A.8. draft-ietf-avtcore-feedback-suppression-rtp-08
The following are the major changes compared to previous version:
o Clarify which RTT is used and how timer is refreshed in the
section 3.
o Editorial changes to the Introduction, Protocol Overview, SDP
Signaling, Message Format, Use case,Security Consideration and
IANA sections.
o Remove Seq Nr field in the figure 2 for payload specific feedback.
o References reorganizing.
A.9. draft-ietf-avtcore-feedback-suppression-rtp-09
The following are the major changes compared to previous version:
o Clarify to suppression interval with regard to how long to receive
the retransmitted packet. Treating TPLR in the same way as
receiving NACK .Replace timer based approach with timeless based
approach
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
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Internet-Draft Third Party Loss Report November 2011
Roni Even
Huawei
14 David Hamelech
Tel Aviv 64953
Israel
Email: even.roni@huawei.com
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