[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-wu-avt-retransmission-supression-rtp) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 RFC 6642

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]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/