XR Block Working Group V. Singh
Internet-Draft Aalto University
Intended status: Standards Track R. Huang
Expires: April 20, 2014 R. Even
Huawei
October 17, 2013
Additional RTP Control Protocol (RTCP) Extended Report (XR) Metrics for
WebRTC Statistics API
draft-singh-xrblock-webrtc-additional-stats-01
Abstract
This document describes a list of additional identifiers used in
WebRTC's Javascript statistics API. These identifiers are a set of
RTCP XR metrics related to the transport of multimedia flows.
Status of This Memo
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Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Candidate XR Block Metrics for WebRTC Statistics API . . . 3
2.1. Variables from XR Blocks . . . . . . . . . . . . . . . . 3
2.1.1. Packets and Octets Discarded . . . . . . . . . . . . 3
2.1.2. Cumulative Number of Retransmitted Packets Received . 4
2.1.3. Cumulative Number of Packets Repaired . . . . . . . . 4
2.1.4. Frame Impairment Metrics . . . . . . . . . . . . . . 4
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Metrics represented using RFC6390 Template . . . . . 6
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 7
B.1. changes in draft-singh-xrblock-webrtc-additional-stats-00 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Web-based real-time communication (WebRTC) deployments are emerging
and applications need to be able to estimate the service quality. If
sufficient information (metrics or statistics) are provided to the
applications, it can attempt to improve the media quality.
[I-D.ietf-rtcweb-use-cases-and-requirements] specifies a requirement
for statistics:
F38 The browser must be able to collect statistics, related to the
transport of audio and video between peers, needed to estimate
quality of experience.
RTCWEB-STATS [I-D.alvestrand-rtcweb-stats-registry] describes a
registration procedure for metrics reported by the Javascript API.
It currently lists basic metrics reported in the RTCP Sender and
Receiver Report (SR/RR) to fulfill this requirement. However, the
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basic metrics from RTCP SR/RR are not sufficient for precise quality
monitoring or troubleshooting. This document proposes to expose the
RTCP XR metrics to better complement the identifiers already in the
statistics registry. In depth discussion about the XR metrics
candidates is carried out in
[I-D.huang-xrblock-rtcweb-rtcp-xr-metrics].
The Javascript application on the receiving endpoint extracts the
statistics for the remote (incoming) media stream from the browser's
RTP using the Stats API [W3C.WD-webrtc-20130910]. There are multiple
ways to exchange these observed identifiers with the remote party,
one of which is to use corresponding RTCP Extension Reports (XRs)
[RFC3611] and query the statistic identifiers for the local
(outgoing) media stream. However, the exchange of statistics of the
local stream are currently outside the scope of WebRTC.
2. Candidate XR Block Metrics for WebRTC Statistics API
This document describes a list of additional identifiers to
complement the identifiers in Section 4.1 of
[I-D.alvestrand-rtcweb-stats-registry] and the group of identifiers
are well defined on a ReportGroup corresponding to an SSRC. In
practice the application MUST be able to query the statistic
identifiers on an incoming media stream (remote stream). Depending
on the support of the corresponding XR report the endpoint MAY be
able to query the statistic identifier for the outgoing media stream
(local stream).
The following contact information is used for all registrations in
this document:
Contact: Varun Singh
mailto:varun.singh@iki.fi
tel:+358-9-470-24785
2.1. Variables from XR Blocks
2.1.1. Packets and Octets Discarded
Name: PacketsDiscarded
Definition: Cumulative Number of RTP packets discarded, Appendix A of
[RFC7002]
Name: OctetsDiscarded
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Definition: Cumulative Number of octets discarded, Appendix A of
[I-D.ietf-xrblock-rtcp-xr-bytes-discarded-metric]
2.1.2. Cumulative Number of Retransmitted Packets Received
Name: PacketsRetx
Definition: See Appendix A of this document, [RFCXXXX].
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC
number, when assigned and remove this note.
2.1.3. Cumulative Number of Packets Repaired
Name: PacketsRepaired
Definition: Appendix A (b) of
[I-D.huang-xrblock-post-repair-loss-count]
2.1.4. Frame Impairment Metrics
Name: FullFramesLostCount
Definition: Number of full frames lost, Appendix A (i) of [RFC7004]
Name: PartialFramesLostCount
Definition: Number of frames partially lost, Appendix A (j) of
[RFC7004]
Name: FramesDiscardedCount
Definition: Number of full frames discarded, Appendix A (g) of
[RFC7004]
3. IANA Considerations
This document requests IANA to update the registry described in
[I-D.alvestrand-rtcweb-stats-registry] with the identifiers defined
in Section 2.
4. Security Considerations
The security considerations of
[I-D.alvestrand-rtcweb-stats-registry], apply.
5. Acknowledgements
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This document is a product of discussion in XRBLOCK WG, initial
motivation for this documented is discussed in
[I-D.huang-xrblock-rtcweb-rtcp-xr-metrics]
The authors would like to thank Al Morton, Colin Perkins, Dan
Romascanu, and Shida Schubert for their valuable comments and
suggestions on earlier version of this document.
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[I-D.alvestrand-rtcweb-stats-registry]
Alvestrand, H., "A Registry for WebRTC statistics
identifiers", draft-alvestrand-rtcweb-stats-registry-00
(work in progress), September 2012.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", RFC 3611, November
2003.
[RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
July 2006.
[RFC7002] Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol
(RTCP) Extended Report (XR) Block for Discard Count Metric
Reporting", RFC 7002, September 2013.
[I-D.ietf-xrblock-rtcp-xr-bytes-discarded-metric]
Singh, V., Ott, J., and I. Curcio, "RTP Control Protocol
(RTCP) Extended Report (XR) for Bytes Discarded Metric",
draft-ietf-xrblock-rtcp-xr-bytes-discarded-metric-00 (work
in progress), October 2013.
[I-D.huang-xrblock-post-repair-loss-count]
Huang, R. and V. Singh, "RTP Control Protocol (RTCP)
Extended Report (XR) for Post-Repair Non-Run Length
Encoding (RLE) Loss Count Metrics", draft-huang-xrblock-
post-repair-loss-count-00 (work in progress), September
2013.
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[RFC7004] Zorn, G., Schott, R., Wu, Q., and R. Huang, "RTP Control
Protocol (RTCP) Extended Report (XR) Blocks for Summary
Statistics Metrics Reporting", RFC 7004, September 2013.
6.2. Informative References
[I-D.ietf-rtcweb-use-cases-and-requirements]
Holmberg, C., Hakansson, S., and G. Eriksson, "Web Real-
Time Communication Use-cases and Requirements", draft-
ietf-rtcweb-use-cases-and-requirements-10 (work in
progress), December 2012.
[I-D.huang-xrblock-rtcweb-rtcp-xr-metrics]
Huang, R., Even, R., and V. Singh, "Consideration for
Selecting RTCP Extended Report (XR) Metrics for RTCWEB
Statistics API", draft-huang-xrblock-rtcweb-rtcp-xr-
metrics-01 (work in progress), July 2013.
[W3C.WD-webrtc-20130910]
Bergkvist, A., Burnett, D., Jennings, C., and A.
Narayanan, "WebRTC 1.0: Real-time Communication Between
Browsers", World Wide Web Consortium WD WD-
webrtc-20130910, September 2013,
<http://www.w3.org/TR/2013/WD-webrtc-20130910>.
Appendix A. Metrics represented using RFC6390 Template
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC
number, when assigned and remove this note.
a. Number of Packets Retransmitted Metric
* Metric Name: Cumulative number of RTP Packets retransmitted
* Metric Description: Total number of packets retransmitted from
the beginning of the session.
* Method of Measurement or Calculation: Cumulative number of
retransmitted packets received from the beginning of the
session. The measured value is an unsigned value. If the
measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE MUST
be reported to indicate an over-range measurement. If the
measurement is unavailable, the value 0xFFFFFFFF MUST be
reported.
* Units of Measurement: The counter is increased by one for
every retransmitted RTP packet that is received.
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* Measurement Point(s) with Potential Measurement Domain: This
metric reports the number of retransmitted RTP packets
received by the receiver. The measurement of these metrics
are made at the receiving end of the retransmission stream and
the association of the retransmission and original streams
should refer to section 5.3 of [RFC4588].
* Measurement Timing: This metric is applicable to cumulative
measurements, which may be the duration of the ongoing RTP
session.
* Use and applications: See section 1 of [RFCXXXX].
* Reporting model: Queried periodically by the WebRTC Statistics
API.
Appendix B. Change Log
Note to the RFC-Editor: please remove this section prior to
publication as an RFC.
B.1. changes in draft-singh-xrblock-webrtc-additional-stats-00
o Clarified measurement points for remote (incoming) media stream
and local (outgoing) media stream.
o Added this section.
Authors' Addresses
Varun Singh
Aalto University
School of Electrical Engineering
Otakaari 5 A
Espoo, FIN 02150
Finland
Email: varun@comnet.tkk.fi
URI: http://www.netlab.tkk.fi/~varun/
Rachel Huang
Huawei
101 Software Avenue, Yuhua District
Nanjing, CN 210012
China
Email: rachel.huang@huawei.com
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Roni Even
Huawei
14 David Hamelech
Tel Aviv 64953
Israel
Email: roni.even@mail01.huawei.com
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