Internet DRAFT - draft-wu-xrblock-rtcp-xr-one-way-delay
draft-wu-xrblock-rtcp-xr-one-way-delay
Audio/Video Transport Working Group R. Brandenburg
Internet-Draft TNO
Intended status: Standards Track K. Gross
Expires: January 14, 2013 AVA Networks
Q. Wu
Huawei
F. Boronat
M. Montagud
UPVLC
July 13, 2012
RTCP XR Report Block for One Way Delay metric Reporting
draft-wu-xrblock-rtcp-xr-one-way-delay-02.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.
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 4
3. One Way Delay Block . . . . . . . . . . . . . . . . . . . . . 5
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in One Way Delay Metrics Report
Block . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Clock synchronization for one way delay metrics . . . . . . . 7
5. One way delay calculation based on measurement method in
RFC2679 . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 10
7.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10
7.3. Contact information for registrations . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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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 the
other way around. 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 and
even symmetric 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 network delay between RTP interfaces in peer RTP end systems, as
measured, for example, using the method described in [RFC2679].
This metrics belong to the class of transport metrics defined in
[MONARCH].
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. The
use of Extended Report blocks is defined by [RFC3611].
1.3. Performance Metrics Framework
The Performance Metrics Framework [RFC6390] provides guidance on the
definition and specification of performance metrics. The RTP
Monitoring Architectures [MONARCH] provides guideline for reporting
block format using RTCP XR. The Metrics Block described in this
document are in accordance with the guidelines in [RFC6390] and
[MONARCH].
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
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 one way packet delay in the stream
arriving at the RTP system.
3.1. Report Block Structure
One Way 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=OWD | I | resv. | block length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Median-One-way-Network-Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max-One-way-Network-Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Min-One-way-Network-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 OWD.
[Note to RFC Editor: please replace OWD with the IANA provided
RTCP XR block type for this block.]
Interval Metric flag (I): 2 bits
This field is used to indicate whether the One Way 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 4.
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.
Median-One-way-Network-Delay: 32 bits
The Mean One way Delay is the mean value of the RTP-to- RTP
interface one way delay in units of 1/65536 seconds over the
measurement period. It can be calculated using RTCP SR/RR or RTP
media packet according to section 3.6 of [RFC2679]. For details
on one way delay calculation, see Section 5.
Max-One-way-Network-Delay: 32 bits
The Max One Way Delay is the maximum value of the RTP- to-RTP
interface one way delay in units of 1/65536 seconds over the
measurement period. It can be calculated using RTCP SR/RR or RTP
media packet according to section 3.6 of [RFC2679]. For details
on one way delay calculation, see Section 5.
Min-One-way-Network-Delay: 32 bits
The Max One Way Delay is the minimum value of the RTP- to-RTP
interface one way delay in units of 1/65536 seconds over the
measurement period. It can be calculated using RTCP SR/RR or RTP
media packet according to section 3.6 of [RFC2679]. For details
on one way delay calculation, see Section 5.
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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, 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. One way delay calculation based on measurement method in RFC2679
TBC.
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6. 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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7. 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].
7.1. New RTCP XR Block Type value
This document assigns the block type value OWD in the IANA "RTCP XR
Block Type Registry" to the "One Way Delay Metrics Block".
[Note to RFC Editor: please replace OWD with the IANA provided RTCP
XR block type for this block.]
7.2. New RTCP XR SDP Parameter
This document also registers a new parameter "one way delay" in the
"RTCP XR SDP Parameters Registry".
7.3. 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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8. 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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9. References
9.1. 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.
9.2. 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-06, May 2012.
[IDMS] Brandenburg, R., Stokking, H., and M. Deventer, "RTCP for
inter-destination media synchronization",
ID draft-ietf-avtcore-idms-05, June 2012.
[MONARCH] Hunt, G., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-17, June 2012.
[RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric
Development", RFC 6390, October 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
Fernando Boronat Segu
Universitat Politecnica de Valencia
IGIC Institute, Campus de Gandia, C/ Paraninfo, 1, Grao de Gandia
Valencia 46730
Spain
Email: fboronat@dcom.upv.es
M. Montagud
Universitat Politecnica de Valencia
IGIC Institute, Campus de Gandia, C/ Paraninfo, 1, Grao de Gandia
Valencia 46730
Spain
Email: mamontor@posgrado.upv.es
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