One document matched: draft-ietf-avtcore-feedback-supression-rtp-16.xml
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<rfc category="std" docName="draft-ietf-avtcore-feedback-supression-rtp-16"
ipr="trust200902">
<front>
<title abbrev="Third-Party Loss Report">RTCP Extension for Third-party
Loss Report</title>
<author fullname="Qin Wu" initials="Q." surname="Wu">
<organization>Huawei</organization>
<address>
<postal>
<street>101 Software Avenue, Yuhua District</street>
<city>Nanjing</city>
<region>Jiangsu</region>
<code>210012</code>
<country>China</country>
</postal>
<email>sunseawq@huawei.com</email>
</address>
</author>
<author fullname="Frank Xia" initials="F." surname="Xia">
<organization>Huawei</organization>
<address>
<postal>
<street>1700 Alma Dr. Suite 500</street>
<city>Plano</city>
<region>TX 75075</region>
<country>USA</country>
</postal>
<phone>+1 972-509-5599</phone>
<email>xiayangsong@huawei.com</email>
</address>
</author>
<author fullname="Roni Even" initials="R." surname="Even">
<organization>Huawei</organization>
<address>
<postal>
<street>14 David Hamelech</street>
<region>Tel Aviv 64953</region>
<country>Israel</country>
</postal>
<email>even.roni@huawei.com</email>
</address>
</author>
<date year="2012" />
<workgroup>Network Working Group</workgroup>
<abstract>
<t>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.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>RTCP feedback messages <xref target="RFC4585"></xref> 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 <xref target="RFC5760"></xref>). There are cases where
multiple receivers may initiate the same, or an equivalent message
towards the same media source or the same feedback target. 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 <xref target="RFC4588"></xref> as
a packet loss recovery technique, sending feedback using RTCP NACK
messages <xref target="RFC4585"></xref> without proper dithering of the
retransmission requests (e.g., not implementing the RFC 4585 dithering
rules or sending NACKs to a feedback target that doesn't redistribute
them to other receivers).</t>
<t>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 <xref
target="RFC4587"></xref>. 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 <xref
target="RFC5104">RFC5104</xref>), can cause an implosion of FIR requests
from receivers to the same media source.</t>
<t>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.
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 and can provide an early indication
before the receiver reacts to the loss and invokes its packet loss
repair machinery. <xref target="Use"></xref> provides some examples of
when to send the Third-Party Loss Report message.</t>
</section>
<section title="Requirements Notation">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119">RFC2119</xref>.</t>
<section title="Glossary">
<t><list hangIndent="6" style="hanging">
<t hangText="TPLR">- Third-Party Loss Report</t>
<t hangText="TLLEI">- Transport Layer Third-Party Loss Early
Indication</t>
<t hangText="PSLEI">- Payload Specific Third-Party Loss Early
Indication</t>
<t hangText="FCI">- Feedback Control Information <xref
target="RFC4585"></xref></t>
<t hangText="AVPF">- The Audio-Visual Profile with RTCP-based
feedback <xref target="RFC4585"></xref></t>
<t hangText="SSRC">- Synchronization Source</t>
<t hangText="BRS">- Burst/Retransmission Sources <xref
target="RFC6285"></xref></t>
<t hangText="FIR">- Full Intra Request <xref
target="RFC5104"></xref></t>
<t hangText="PLI">- Picture Loss Indication <xref
target="RFC4585"></xref></t>
<t hangText="SSM">- Source Specific Multicast <xref
target="RFC5760"></xref></t>
<t hangText="RAMS">- Unicast based Rapid Acquisition of Multicast
Stream <xref target="RFC6285"></xref></t>
<t hangText="MCU">- Multipoint Control Unit <xref
target="RFC5117"></xref></t>
</list></t>
</section>
</section>
<section title="Protocol Overview">
<t>This document extends the RTCP feedback messages defined in the
RTP/AVPF <xref target="RFC4585"></xref> defining a RTCP Third-Party Loss
Report (TPLR) message. The RTCP TPLR message can be used by the
intermediaries to inform the receiver that the sender of the RTCP TPLR
has received reports that the indicated packets were lost, and asks the
receiver not to send feedback to it regarding these packets.
Intermediaries are variously referred to as Distribution source,
Burst/Retransmission Sources (BRS), MCUs, RTP translator, or RTP mixers,
depending on the precise use case described <xref
target="Use"></xref>.</t>
<t>RTCP TPLR follows the similar format of message type as RTCP NACK or
Full Intra Request Command. However, the RTCP TPLR is defined as an
indication that the sender of the feedback has received reports that the
indicated packets were lost, while NACK <xref target="RFC4585"></xref>
just indicates that the sender of the NACK observed that these packets
were lost. The RTCP TPLR message is generated by an intermediary that
may not have seen the actual packet loss. It is sent following the same
timing rule as sending NACK defined in <xref
target="RFC4585">RFC4585</xref>. The RTCP TPLR message may be sent in a
regular full compound RTCP packet or in an early RTCP packet, as per the
RTP/AVPF rules. Intermediaries in the network that receive a RTCP TPLR
SHOULD NOT send their own additional Third-Party Loss Report messages
for the same packet sequence numbers. They SHOULD simply forward the
RTCP TPLR message received from upstream direction to the receiver(s),
additionally, they may generate their own RTCP TPLR that reports a set
of the losses they see, which are different from ones reported in the
RTCP TPLR they received. The RTCP TPLR does not have the retransmission
request <xref target="RFC4588"></xref> semantics.</t>
<t>When a receiver gets a RTCP TPLR message, it MUST follow the rules
for NACK suppression in <xref target="RFC4585">RFC4585</xref>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.</t>
<t>To increase the robustness to the loss of a TPLR, The RTCP TPLR may
be retransmitted. If the additional TPLR arrives at receiver, the
receiver SHOULD deal with the additional TPLR in the same way as
receiving the first TPLR for the same packet and no additional behavior
for receiver is required.</t>
<t>A receiver may have sent a Feedback message according to the RTP/AVPF
scheduling algorithm of <xref target="RFC4585">RFC4585</xref> before
receiving a RTCP TPLR message, but further feedback messages for those
sequence numbers SHOULD be suppressed after receiving the RTCP TPLR.
Nodes that do not understand the RTCP TPLR message will ignore it, and
might therefore still send feedback according to the AVPF scheduling
algorithm of <xref target="RFC4585">RFC4585</xref>. The media source or
intermediate nodes cannot be certain that the use of a RTCP TPLR message
actually reduces the amount of feedback it receives.</t>
</section>
<section anchor="sec4" title="Format of RTCP Feedback Messages">
<t>This document introduces two new RTCP Feedback messages for Third
Party Loss Report. Applications that are employing one or more loss-
repair methods MAY use the RTCP TPLR 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.</t>
<t>The following two sections each define a RTCP TPLR message. Both
messages are feedback messages as defined in section 6.1 of <xref
target="RFC4585">RFC4585</xref>, and use the header format defined
there. Each section defines how to populate the PT, FMT,length SSRC of
packet sender, SSRC of media source, and FCI fields in that header.</t>
<section title="Transport Layer Feedback: Third-Party Loss Report (TPLR)">
<t>This TPLR message is identified by RTCP packet type value PT=RTPFB
and FMT=TBA1.</t>
<t>Within the common packet header for feedback messages (as defined
in section 6.1 of <xref target="RFC4585">RFC4585</xref>), the "SSRC of
packet sender" field 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.</t>
<t>The Feedback Control Information (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 field in the TLLEI feedback message MUST be set to 2+1*N,
where N is the number of FCI entries.</t>
<t>The FCI field for TLLEI uses the similar format of message Types
defined in the section 6.2.1 of <xref target="RFC4585">RFC4585</xref>.
The format is shown in <xref target="fig2"></xref>.</t>
<figure align="center" anchor="fig2"
title="Syntax of an FCI Entry in the TLLEI Feedback Message">
<artwork>
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</artwork>
</figure>
<t><list style="hanging">
<t hangText="Packet ID (PID): 16 bits"><vspace blankLines="1" />
The PID field is used to specify a lost packet. The PID field
refers to the RTP sequence number of the lost packet.<vspace
blankLines="1" /></t>
<t hangText="bitmask of lost packets (BLP): 16 bits"><vspace
blankLines="1" /> 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 the
section 6.2.1 of <xref target="RFC4585"></xref>.<vspace
blankLines="1" /></t>
</list></t>
</section>
<section title="Payload Specific Feedback: Third-Party Loss Report (TPLR)">
<t>This TPLR message is identified by RTCP packet type value PT=PSFB
and FMT=TBA2, which is used to suppress FIR <xref
target="RFC5104"></xref> and PLI <xref target="RFC4585"></xref>.</t>
<t>Within the common packet header for feedback messages (as defined
in section 6.1 of <xref target="RFC4585">RFC4585</xref>), 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.</t>
<t>The FCI field for a Payload Specific Third-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 field in the
PSLEI feedback message MUST be set to 2+1*N, where N is the number of
FCI entries.</t>
<t>The format is shown in <xref target="fig3"></xref>.</t>
<figure align="center" anchor="fig3"
title="Syntax of an FCI Entry in the PSLEI Feedback Message">
<artwork>
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</artwork>
</figure>
<t><list style="hanging">
<t hangText="Synchronization source (SSRC):32 bits"><vspace
blankLines="1" />The SSRC value of the media source that is
already aware, or in the process of being made aware, that some
receiver lost synchronization with the media stream and for which
the PSLEI receiver's own response to any such error is
suppressed.<vspace blankLines="1" /></t>
</list></t>
</section>
</section>
<section title="SDP Signaling">
<t>The Session Description Protocol (SDP) <xref target="RFC4566"></xref>
attribute, rtcp-fb, is defined in the Section 4 of <xref
target="RFC4585">RFC4585</xref> and may be used to negotiate the
capability to handle specific AVPF commands and indications. The ABNF
for rtcp-fb is described in section 4.2 of <xref
target="RFC4585">RFC4585</xref>. In this section, we extend the rtcp-fb
attribute to include the commands and indications that are described for
third-party loss report in the present document.</t>
<t>In the ABNF <xref target="RFC5234"></xref> for rtcp-fb-val defined in
<xref target="RFC4585">RFC4585</xref>, the feedback type "nack", without
parameters, indicates use of the Generic NACK feedback format as defined
in Section 6.2.1of <xref target="RFC4585">RFC4585</xref>. In this
document, we define two parameters that indicate the third-party loss
supported for use with "nack", namely: <vspace blankLines="1" /><list
style="symbols">
<t>"tllei" denotes support of transport layer third-party loss early
indication.<vspace blankLines="1" /></t>
<t>"pslei" denotes support of payload specific third-party loss
early indication.</t>
</list><vspace blankLines="1" />The ABNF for these two parameters for
"nack" is defined here (please refer to section 4.2 of <xref
target="RFC4585">RFC4585</xref> for complete ABNF syntax).</t>
<figure align="center">
<artwork>
rtcp-fb-val =/ "nack" rtcp-fb-nack-param
rtcp-fb-nack-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] >
</artwork>
</figure>
<t>Refer to Section 4.2 of <xref target="RFC4585">RFC4585</xref> for a
detailed description and the full syntax of the "rtcp-fb" attribute.</t>
</section>
<section anchor="Use" title="Example Use Cases">
<t>The operation of feedback suppression is similar for all types of RTP
sessions and topologies <xref target="RFC5117"></xref>, 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.</t>
<section title="Source Specific Multicast (SSM) use case">
<t>In SSM RTP sessions as described in "RTP Control Protocol (RTCP)
Extensions for Single-Source Multicast Sessions with Unicast Feedback"
<xref target="RFC5760"></xref>, 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.</t>
<t>As outlined in the <xref target="RFC5760">RFC5760</xref>, 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 RTCP TPLRs, instead, RTCP 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 RTCP TPLR message to the systems that were unable to receive
the NACK, and won't receive the NACK via other means. The RTCP TPLR
can be generated at the distribution source when downstream loss is
reported (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 (i.e., unable receive the NACK) by sending
this RTCP TPLR message to all the relevant receivers impacted by the
packet loss.</t>
</section>
<section title="Unicast based Rapid Acquisition of Multicast Stream (RAMS) use case">
<t>The typical RAMS architecture <xref target="RFC6285"></xref> 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 RTCP NACK or RTCP TPLR message to
the DS, where the SSRC in this RTCP NACK or RTCP 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 <xref target="RETRANSMISSION-FOR-SSM"></xref>.</t>
</section>
<section title="RTP Transport Translator use case">
<t>A Transport Translator (Topo-Trn-Translator), as defined in <xref
target="RFC5117">RFC5117</xref> 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 RTCP TPLR message received from upstream in
the same way as forwarding other RTCP traffic. If the translator
acting as the monitor <xref target="MONARCH"></xref> 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 are not aware of
packet loss.</t>
</section>
<section title="Multipoint Control Unit (MCU) use case">
<t>When the speaker is changed in a voice-activated multipoint video
switching conference <xref target="RFC4587"></xref>, 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 RTCP TPLR
message.</t>
</section>
<section title="Mixer use case">
<t>A Mixer, in accordance with <xref target="RFC5117">RFC5117</xref>,
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 RTCP TPLR 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.</t>
</section>
</section>
<section title="Security Considerations">
<t>The security considerations documented in <xref target="RFC4585">
</xref> are also applicable for the TPLR messages defined in this
document.</t>
<t>More specifically, spoofed or maliciously created TPLR feedback
messages cause missing RTP packets to not be repaired in a timely
fashion and add risk of (undesired) feedback supression at RTCP
receivers that accept such TPLR messages. Any packet loss detected by a
receiver and where this RTP receiver also receives a TPLR message for
the same missing packet(s), will negatively impact the application that
relies on the (timely) RTP retransmission capabilities. </t>
<t>A solution to prevent such attack with maliciously sent TPLR
messages, is to apply an authentication and integrity protection
framework for the feedback messages. This can be accomplished using the
RTP profile that combines Secure RTP <xref target="RFC3711">
</xref> and AVPF into SAVPF <xref target="RFC5124"></xref>.</t>
<t>Note that intermediaries 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 intermediary is visible at the
RTP layer, this is not an issue, provided the intermediary is part of
the security context for the session.</t>
</section>
<section title="IANA Consideration">
<t>This document instructs IANA to add two values to the '"ack" and
"nack" Attribute Values' sub-registry <xref target="RFC4585"></xref> of
the 'Session Description Protocol (SDP) Parameters' registry.<figure>
<artwork>
The value registration for the attribute value "nack":
Value name: tllei
Long name: Transport Layer Third-Party Loss Early Indication
Usable with: nack
Reference: RFC 4585.
Value name: pslei
Long name: Payload Specific Third-Party Loss Early Indication
Usable with: nack
Reference: RFC 4585.
</artwork>
</figure></t>
<t>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 <figure
align="center">
<artwork>
RTPFB range
Name Long Name Value Reference
-------------- --------------------------------- ----- ---------
TLLEI Transport Layer Third-Party TBA1 [RFCXXXX]
Loss Early Indication
</artwork>
</figure></t>
<t>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 <figure
align="center">
<artwork>
PSFB range
Name Long Name Value Reference
-------------- --------------------------------- ----- --------
PSLEI Payload Specific Third-Party TBA2 [RFCXXXX]
Loss Early Indication
</artwork>
</figure></t>
</section>
<section title="Acknowledgement">
<t>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.</t>
</section>
</middle>
<back>
<references title="Normative References">
<reference anchor="RFC2119">
<front>
<title abbrev="RFC Key Words">Key words for use in RFCs to Indicate
Requirement Levels</title>
<author fullname="Scott Bradner" initials="S." surname="Bradner">
<organization>Harvard University</organization>
<address>
<postal>
<street>1350 Mass. Ave.</street>
<street>Cambridge</street>
<street>MA 02138</street>
</postal>
<phone>- +1 617 495 3864</phone>
<email>sob@harvard.edu</email>
</address>
</author>
<date month="March" year="1997" />
<area>General</area>
<keyword>keyword</keyword>
<abstract>
<t>In many standards track documents several words are used to
signify the requirements in the specification. These words are
often capitalized. This document defines these words as they
should be interpreted in IETF documents. Authors who follow these
guidelines should incorporate this phrase near the beginning of
their document: <list>
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described
in RFC 2119.</t>
</list></t>
<t>Note that the force of these words is modified by the
requirement level of the document in which they are used.</t>
</abstract>
</front>
</reference>
<?rfc include="reference.RFC.4585"?>
<?rfc include="reference.RFC.4588"?>
<?rfc include="reference.RFC.4566"?>
<?rfc include="reference.RFC.5234"?>
<?rfc include="reference.RFC.5104"?>
<?rfc include="reference.RFC.3711"?>
<?rfc include="reference.RFC.5124"?>
</references>
<references title="Informative References">
<reference anchor="RFC6285">
<front>
<title>Unicast- Based Rapid Acquisition of Multicast RTP
Sessions</title>
<author fullname="Bill Steeg" initials="B." surname="Steeg">
<organization>Cisco</organization>
</author>
<author fullname="Ali Begen" initials="A." surname="Begen">
<organization>Cisco</organization>
</author>
<author fullname="Tom Caenegem" initials="T." surname="Caenegem">
<organization>Alcatel-Lucent</organization>
</author>
<author fullname="Zeev Vax" initials="Z." surname="Vax">
<organization>Microsoft</organization>
</author>
<date month="June" year="2011" />
</front>
</reference>
<reference anchor="MONARCH">
<front>
<title>Monitoring Architectures for RTP</title>
<author fullname="Qin Wu" initials="Q." surname="Wu">
<organization>Huawei</organization>
</author>
<author fullname="Geoff Hunt" initials="G." surname="Hunt">
<organization>naffiliated</organization>
</author>
<author fullname="Philip Arden" initials="P." surname="Arden">
<organization>BT</organization>
</author>
<date month="June" year="2011" />
</front>
</reference>
<reference anchor="RETRANSMISSION-FOR-SSM">
<front>
<title>Retransmission for Source-Specific Multicast (SSM)
Sessions</title>
<author fullname="Tom Caenegem" initials="T." surname="Caenegem">
<organization>Alcatel-Lucent</organization>
</author>
<author fullname="Bill Steeg" initials="B." surname="Steeg">
<organization>Cisco</organization>
</author>
<author fullname="Ali Begen" initials="A." surname="Begen">
<organization>Cisco</organization>
</author>
<date month="May" year="2011" />
</front>
</reference>
<?rfc include="reference.RFC.5117"?>
<?rfc include="reference.RFC.4587"?>
<?rfc include="reference.RFC.5760"?>
</references>
<section title="Change Log">
<t>Note to the RFC-Editor: please remove this section prior to
publication as an RFC.</t>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-01">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Remove the merge report from SSM use case and additional text
to address report merging issue.<vspace blankLines="1" /></t>
<t>Revise section 3 and section 6 to address FEC packet dealing
issue and Leave how to repair packet loss beyond the scope.<vspace
blankLines="1" /></t>
<t>Modify the SSM use case and RAMS use case to focus on
uses.<vspace blankLines="1" /></t>
<t>Other Editorial changes.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-02">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>In Section 4.1, fix typo: change Section 4.3.1.1 of section
[RFC5104] to section 6.2.1 of [RFC4585].<vspace
blankLines="1" /></t>
<t>In Section 3: Clarify how to deal with downstream loss using
Third-party loss report and upstream loss using NACK.<vspace
blankLines="1" /></t>
<t>Update title and abstract to focus on third-party loss
report.<vspace blankLines="1" /></t>
<t>In Section 6.1: Update this section to explain how third party
loss report is used to deal with downstream loss.<vspace
blankLines="1" /></t>
<t>In section 6.1.2: Update this section to explain how third
party loss report is used to deal with downstream loss.<vspace
blankLines="1" /></t>
<t>In section 6.2: Rephrase the text to discuss how BRS deal with
the third-party loss report.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-03">
<t>The following are the major changes compared to previous
version:<vspace blankLines="1" /><list style="symbols">
<t>In Appendix A, fix typo: Appendix A. Appendix A. -> Appendix
A.<vspace blankLines="1" /></t>
<t>Update abstract to clarify when third-party loss reports should
be sent instead of NACKs.<vspace blankLines="1" /></t>
<t>Update section 3 Paragraph 2 to differentiate when a
third-party loss report should be used compared to a NACK.<vspace
blankLines="1" /></t>
<t>Update section 3 Paragraph 3 to explain when media source to
send a third-party loss.<vspace blankLines="1" /></t>
<t>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.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-04">
<t>The following are the major changes compared to previous version:
<list style="symbols">
<t>Reference Update.<vspace blankLines="1" /></t>
<t>Clarify the use of the third-party loss report in section 3 and
section 6.1.1.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-05">
<t>The following are the major changes compared to previous version:
<list style="symbols">
<t>Remove 3rd and 4th paragraphs of section 6.1 and replaced them
with 2nd and 3rd paragraphs of section 3.<vspace
blankLines="1" /></t>
<t>Remove section 6.1.1.1.<vspace blankLines="1" /></t>
<t>Revise the last paragraph of section 1 to clarify the rationale
of using new message.<vspace blankLines="1" /></t>
<t>Update RTP transport translator case in section 6.3 to correct
the use of the third-party loss report.<vspace
blankLines="1" /></t>
<t>Update MCU case in section 6.4 to correct the use of the third
party loss report.<vspace blankLines="1" /></t>
<t>Revise SSM use case to address multiple DS issue.<vspace
blankLines="1" /></t>
<t>References Update.<vspace blankLines="1" /></t>
<t>Move one rationale on preventing sending unicast NACK in
introduction section to SSM case section.<vspace
blankLines="1" /></t>
<t>Other Editorial changes to section 6.1, 6.1.1, 6.2.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-06">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>A few Editorial changes to the whole document.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-07">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Restructuring the protocol overview section to clarify the
round trip<vspace blankLines="1" /> time calculation and receiver
behavior to the additional TPLR.<vspace blankLines="1" /></t>
<t>Restructuring the SSM use case section to focus on the use of
TPLR.<vspace blankLines="1" /></t>
<t>Editorial changes to the abstract, introduction, message
format, use cases and IANA sections.<vspace blankLines="1" /></t>
<t>References update</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-08">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Clarify which RTT is used and how timer is refreshed in the
section 3.<vspace blankLines="1" /></t>
<t>Editorial changes to the Introduction, Protocol Overview,
SDP<vspace blankLines="1" />Signaling, Message Format, Use
case,Security Consideration and IANA sections.<vspace
blankLines="1" /></t>
<t>Remove Seq Nr field in the figure 2 for payload specific
feedback.<vspace blankLines="1" /></t>
<t>References reorganizing.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-09">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Clarify to suppression interval with regard to how long to
receive the<vspace blankLines="1" />retransmitted packet. Treating
TPLR in the same way as receiving NACK.<vspace
blankLines="1" /></t>
<t>Replace timer based approach with timeless based approach.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-10">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Fix the definition of Synchronization source for TPLR in
section 4.2.<vspace blankLines="1" /></t>
<t>Associate SDP parameters tllei and pslei with "nack".<vspace
blankLines="1" /></t>
<t>Remove the packet loss recovery from TPLR loss handling
part.<vspace blankLines="1" /></t>
<t>Other typo fixed.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-11">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Additional Editorial changes.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-12">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Additional Editorial changes.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-13">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Additional Editorial changes.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-14">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Two References moving to normative refereces.<vspace
blankLines="1" /></t>
<t>Revise IANA section to clarify whether to create new registry
or add new value to the existing registry.<vspace
blankLines="1" /></t>
<t>Revise Security section to clarify ill effect of accepting
unauthenticated messages.<vspace blankLines="1" /></t>
<t>Add a glossary to fix acronym issue.<vspace
blankLines="1" /></t>
<t>Other Editorial changes.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-15">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Some Editorial changes.</t>
</list></t>
</section>
<section title="draft-ietf-avtcore-feedback-suppression-rtp-16">
<t>The following are the major changes compared to previous version:
<vspace blankLines="1" /><list style="symbols">
<t>Some Editorial changes.</t>
</list></t>
</section>
</section>
</back>
</rfc>
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