RTCP XR Report Block for One Way Delay metric Reporting
draft-wu-xrblock-rtcp-xr-one-way-delay-00
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| Authors | Kevin Gross , Mario Montagud | ||
| Last updated | 2012-01-05 | ||
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draft-wu-xrblock-rtcp-xr-one-way-delay-00
Audio/Video Transport Working Group R. Brandenburg
Internet-Draft TNO
Intended status: Standards Track K. Gross
Expires: July 8, 2012 AVA Networks
Q. Wu
Huawei
F. Boronat
M. Montagud
Universidad Politecnica de
Valencia
January 5, 2012
RTCP XR Report Block for One Way Delay metric Reporting
draft-wu-xrblock-rtcp-xr-one-way-delay-00.txt
Abstract
This document defines an RTCP XR Report Block that allows the
reporting of One Way Delay metrics for use in a range of RTP
applications.
Status of this Memo
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Packet One Way Delay Metrics Block . . . . . . . . . . . . 3
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5
3. One Way Delay Block . . . . . . . . . . . . . . . . . . . . . 6
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6
3.2. Definition of Fields in One Way Delay Metrics Report
Block . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Clock synchronization for one way delay metrics . . . . . . . 9
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 11
6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 11
6.3. Contact information for registrations . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
1.1. Packet One Way Delay Metrics Block
[I-D.ietf-xrblock-rtcp-xr-delay] defines the new block type
supporting the reporting of the mean, minimum and maximum values of
the network round-trip delay between media source(source) and media
receiver(destination). However none of these metrics allow a
receiver to report one way delay from source to destination or from
destination to source. As described in [RFC2679], the path from a
source to a destination may be different than the path from the
destination back to the source. Even when the two paths are
symmetric, they may have radically different performance
characteristics. Therefore the measurement of one-way delay can not
be roughly estimated by the round-trip delay for many applications in
the asymmetric network.
This draft defines a new block type to augment those defined in
[RFC3611] for use in a range of RTP applications. The new block type
supports the reporting of the mean, minimum, maximum values of one
way delay between RTP interfaces in peer RTP end systems, as well as
the percentile and inverse-percentile (regarding a threshold value),
already defined in RFC 2679, as measured, for example, using the RTCP
method described in [RFC3550].
This metrics belong to the class of transport metrics defined in
[MONARCH] (work in progress).
1.2. RTCP and RTCP XR Reports
The use of RTCP for reporting is defined in [RFC3550]. [RFC3611]
defined an extensible structure for reporting using an RTCP Extended
Report (XR). This draft defines a new Extended Report block that
MUST be used as defined in [RFC3550] and [RFC3611].
1.3. Performance Metrics Framework
The Performance Metrics Framework [PMOLFRAME] provides guidance on
the definition and specification of performance metrics. Metrics
described in this draft either reference external definitions or
define metrics generally in accordance with the guidelines in
[PMOLFRAME].
1.4. Applicability
These metrics are applicable to a range of delay-sensitive RTP
applications in which this report block would be useful, such as some
IDMS use cases (e.g., video wall, network games, networked
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loudspeakers, etc., see Draft IDMS [IDMS]).
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2. Terminology
2.1. Standards Language
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 [RFC2119].
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3. One Way Delay Block
Metrics in this block report on packet one way delay in the stream
arriving at the RTP system.
3.1. Report Block Structure
Delay metrics block
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=OWDEL | I | resv. | block length = 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time Duration Threshold |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| One-way-Delay-Percentile. | One-way-Delay-Inver-Percentile |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| One-way-Delay-Median |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max-One-way-Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Min-One-way-Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure
3.2. Definition of Fields in One Way Delay Metrics Report Block
Block type (BT): 8 bits
A One way Delay Report Block is identified by the constant NOWDEL.
[Note to RFC Editor: please replace NOWDEL with the IANA provided
RTCP XR block type for this block.]
Interval Metric flag (I): 2 bit
This field is used to indicate whether the QoE Metrics are
Sampled, Interval or Cumulative metrics [MONARCH], that is,
whether the reported values applies to the most recent measurement
interval duration between successive metrics reports (I=10) (the
Interval Duration), to the accumulation period characteristic of
cumulative measurements (I=11) (the Cumulative Duration) or is a
sampled instantaneous value (I=01).
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Reserved (resv): 6 bits
These bits are reserved. They SHOULD be set to zero by senders
and MUST be ignored by receivers.
block length: 16 bits
The length of this report block in 32-bit words, minus one. For
the Delay block, the block length is equal to 6.
SSRC of source: 32 bits
The SSRC of the media source shall be set to the value of the SSRC
identifier carried in the RTP header [RFC3550] of the RTP packet
to which the XR relates.
Time Duration Threshold: 32 bits
This field is associated with the one-way-delay-percentile and
one-way-delay-inver-percentile and expressed in Milliseconds or
microseconds depending on which clock source is used and the
requirement for synchronization accuracy (see section 4).
One-way-Delay-Percentile: 16 bits
The percentages of packets in the RTP stream for which individual
packet one way delays were less than the Threshold.
One-way-Delay-Inver-Percentile: 16 bits
The percentages of packets in the RTP stream for which individual
packet one way delays were more than the Threshold.
One-way-Delay-Median: 32 bits
The Mean One way Delay is the mean value of the RTP-to- RTP
interface one way delay in ms or us over the measurement period,
typically determined using RTCP SR/RR. This value is generated
according to section 3.6 of [RFC2679].
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Max-One-way-Delay: 32 bits
The Max One Way Delay is the maximum value of the RTP- to-RTP
interface one way delay in ms or us over the measurement period,
typically determined using RTCP SR/RR. This value is generated
according to section 3.6 of [RFC2679].
Min-One-way-Delay: 32 bits
The Max One Way Delay is the minimum value of the RTP- to-RTP
interface one way delay in ms or us over the measurement period,
typically determined using RTCP SR/RR. This value is generated
according to section 3.6 of [RFC2679].
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4. Clock synchronization for one way delay metrics
This subsection provides informative guidance on use of methodology
for one way delay metrics measurement.
As specified in the methodology of [RFC2679], it is important for
media source (Src) and media receiver (Dst) to synchronize very
closely since one way delay values will often be as low as the 100
usec to 10 msec range. In order to arrange Src and Des synchronized
before measurement method is applied, clock synchronization SDP
attribute defined in [I-D.brandenburg-mmusic-clock-synchronization],
[IDMS] is used to signal the clock synchronization source or sources
used or able to be used. A participant at the Dst can indicate which
synchronization source is being used at the moment. A participant
can also indicate any other synchronization sources available to it.
This allows multiple participants in an RTP session to use the same
or a similar clock synchronization source for their session.
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5. SDP Signaling
[RFC3611] defines the use of SDP (Session Description Protocol)
[RFC4566] for signaling the use of XR blocks. XR blocks MAY be used
without prior signaling.
This section augments the SDP [RFC4566] attribute "rtcp-xr" defined
in [RFC3611] by providing an additional value of "xr-format" to
signal the use of the report block defined in this document.
rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF
(defined in [RFC3611])
xr-format =/ xr-one-way-delay-block
xr-one-way-delay-block ="one way delay"
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6. IANA Considerations
New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to
[RFC3611].
6.1. New RTCP XR Block Type value
This document assigns the block type value NOWDEL in the IANA "RTCP
XR Block Type Registry" to the "One Way Delay Metrics Block".
[Note to RFC Editor: please replace NOWDEL with the IANA provided
RTCP XR block type for this block.]
6.2. New RTCP XR SDP Parameter
This document also registers a new parameter "one way delay" in the
"RTCP XR SDP Parameters Registry".
6.3. Contact information for registrations
The contact information for the registrations is:
Qin Wu (sunseawq@huawei.com)
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
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7. Security Considerations
It is believed that this proposed RTCP XR report block introduces no
new security considerations beyond those described in [RFC3611].
This block does not provide per-packet statistics so the risk to
confidentiality documented in Section 7, paragraph 3 of [RFC3611]
does not apply.
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8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
Delay Metric for IPPM", RFC 2679, September 1999.
[RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", November 2003.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", July 2006.
8.2. Informative References
[I-D.ietf-xrblock-rtcp-xr-delay]
Hunt, G., Clark, A., Gross, K., and Q. Wu, "RTCP XR Report
Block for Delay metric Reporting",
ID draft-ietf-xrblock-rtcp-xr-delay-01, December 2011.
[IDMS] Brandenburg, R., Stokking, H., and M. Deventer, "RTCP for
inter-destination media synchronization",
ID draft-ietf-avtcore-idms-02, October 2011.
[MONARCH] Hunt, G., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-04, August 2011.
[PMOLFRAME]
Clark, A. and B. Claise, "Framework for Performance Metric
Development", ID draft-ietf-pmol-metrics-framework-12,
July 2011.
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Authors' Addresses
R.van Brandenburg
TNO
Email: ray.vanbrandenburg@tno.nl
Kevin Gross
AVA Networks
Email: kevin.gross@avanw.com
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
F.Boronat
Universidad Politecnica de Valencia
Email: fboronat@dcom.upv.es
M. Montagud
Universidad Politecnica de Valencia
Email: mamontor@posgrado.upv.es
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