Audio/Video Transport Working Group G. Hunt
Internet-Draft Unaffiliated
Intended status: Standards Track A. Clark
Expires: March 29, 2012 Telchemy
Q. Wu
Huawei
September 26, 2011
RTCP Source Description (SDES) items for Measurement Identity
draft-ietf-xrblock-rtcp-xr-meas-identity-00.txt
Abstract
This document defines RTCP SDES items carrying parameters which
identify a measurement, to which one or more other RTCP XR Report
Blocks may refer.
Status of this Memo
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Measurement Identity SDES Items . . . . . . . . . . . . . . . 4
2.1. APSI: Application Specific Identifier SDES Item . . . . . 4
2.2. EXFS: extended first sequence number SDES Item . . . . . . 4
2.3. EXLS: extended last sequence number SDES Item . . . . . . 5
2.4. CUMD: Cumulative Measurement Duration SDES Item . . . . . 5
2.5. INMD: Interval Measurement Duration SDES Item . . . . . . 5
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
3.1. New RTCP SDES Type value . . . . . . . . . . . . . . . . . 6
3.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 6
3.3. Contact information for registrations . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Normative References . . . . . . . . . . . . . . . . . . . 8
5.2. Informative References . . . . . . . . . . . . . . . . . . 8
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 9
A.1. draft-ietf-xrblock-rtcp-sdes-meas-identity-00 . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
This draft defines new RTCP SDES items to carry parameters which
identify a measurement for use in a range of RTP applications. These
SDES items do not itself contain any measurement results (metrics).
However, they provide information relevant to a measurement reported
in one or more other block types, including
o a field for incorporation of an application-specific auxiliary
identifier,
o the sequence number of the first packet of the RTP session,
o the extended sequence numbers of the first packet of the current
measurement interval, and the last packet included in the
measurement,
o the duration of the most recent measurement interval and
o the duration of the interval applicable to cumulative measurements
(which may be the duration of the RTP session to date).
The method for calculation of the extended RTP sequence number is
provide in [RFC3550].
The RTCP SDES packet containing these item is intended to provide a
single copy of the information necessary to relate measurement data
in the RTCP XR blocks to the stream, and measurement period, to which
they refer. Commonly, multiple other small metric blocks contain
measurement data for the same stream and period, and it would be a
large overhead if all of these metric blocks carried duplicated data
for measurement identification. Other blocks make a reference to
this block (by SSRC). A Measurement Identity SDES packet is
associated with the set of RTCP XR metrics blocks which share the
same SSRC value. There MAY be several such sets in an RTCP packet,
up to a limit of 8 arising from the use of 3-bit tags. There MAY
also be RTCP XR blocks in the packet which are not associated with a
Measurement Identity block, for example blocks which were defined
before the Measurement Identity mechanism was introduced by this
document.
1.1. Applicability
The RTPC SDES items provide identification information for members of
a family of RTCP XR metrics blocks which are designed to use it. To
use the mechanism defined here, a metrics block must be in the same
RTCP packet as the SDES packet for Measurement Identity.
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2. Measurement Identity SDES Items
This section defines the format of Measurement Identity SDES items.
These SDES items are carried in the RTCP SDES packet. The packet
format for the RTCP SDES is defined in Section 6.5 of [RFC3550].
Each SDES packet has a fixed-length field for version,source count,
parcket type (PT), length as well as a variable-length field for SDES
items. In the SDES packets, the PT field is set to SDES (202).
2.1. APSI: Application Specific Identifier SDES Item
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| APSI=TBD | length |application specific identifier
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ....
+-+-+-+-+-+-+-+-+
Application specific identifier is an additional identifier which is
useful in the context of a specific application, e.g. an MPEG-2
transport identifier [MPEG2]. Where the identifier is less than 32
bits, the identifier SHOULD be mapped into the most significant bits
of the field. If no additional identifier is provided, all bits of
the field MUST be set to zero. This field MUST be ignored by
applications which are not configured to make use of it.
2.2. EXFS: extended first sequence number SDES Item
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| APSI=TBD | length | extended first sequence number
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| of interval ....
+-+-+-+-+-+-+-+-+
The RTP sequence number of the first received RTP packet of the
session, used to determine the number of packets contributing to
cumulative measurements.
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2.3. EXLS: extended last sequence number SDES Item
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| APSI=TBD | length | extended last sequence number
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ....
+-+-+-+-+-+-+-+-+
The extended RTP sequence number of the last received RTP packet
which contributed to this measurement.
2.4. CUMD: Cumulative Measurement Duration SDES Item
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| APSI=TBD | length | Measurement Duration (Cumulative)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (ms) ....
+-+-+-+-+-+-+-+-+
The duration in ms of the reporting interval applicable to Cumulative
reports which use this Measurement Identity block.
2.5. INMD: Interval Measurement Duration SDES Item
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| APSI=TBD | length | Measurement Duration (Interval)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (ms) ....
+-+-+-+-+-+-+-+-+
The duration in ms of the reporting interval applicable to Interval
reports which use this Measurement Identity block.
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3. IANA Considerations
New SDES types for RTCP SDES are subject to IANA registration. For
general guidelines on IANA considerations for RTCP SDES, refer to
[RFC3550].
3.1. New RTCP SDES Type value
This document assigns additional five SDES types in the IANA "RTCP XR
Block Type Registry" to the Measurement Identity SDES items as
follow:
abbrev. name value
APSI: Application Specific Identifier TBD
EXFS: extended first sequence number TBD
EXLS: extended last sequence number TBD
CUMD: Cumulative Measurement Duration TBD
INMD: Interval Measurement Duration TBD
[Note to RFC Editor: please replace APSI,EXF,EXLS,CUMD,INMD with the
IANA provided RTCP SDES type for these SDES items.]
3.2. New RTCP XR SDP Parameter
This document also registers a new parameter "jitter-bfr" in the
"RTCP XR SDP Parameters Registry".
3.3. 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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4. Security Considerations
RTCP reports can contain sensitive information since they can provide
information about the nature and duration of a session established
between two or more endpoints.Therefore, the use of security
mechanisms with RTP documented in Section 9 of [RFC3550] should
apply.
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5. References
5.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003.
5.2. Informative References
[MONARCH] Wu, Q., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-04, August 2011.
[MPEG2] "ISO/IEC, "Standard 13818-1"", December 2000.
[PMOLFRAME]
Clark, A. and B. Claise, "Framework for Performance Metric
Development", ID draft-ietf-pmol-metrics-framework-12,
July 2011.
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Appendix A. Change Log
Note to the RFC-Editor: please remove this section prior to
publication as an RFC.
A.1. draft-ietf-xrblock-rtcp-sdes-meas-identity-00
The following are the major changes to
draft-ietf-avt-rtcp-xr-meas-identity-02:
o Change the use of SDES item to convey measurement identity instead
of XR Block in section 2.
o Update references.
o Update security section and remove SDP signaling section.
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Authors' Addresses
Geoff Hunt
Unaffiliated
Email: r.geoff.hunt@gmail.com
Alan Clark
Telchemy Incorporated
2905 Premiere Parkway, Suite 280
Duluth, GA 30097
USA
Email: alan.d.clark@telchemy.com
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: sunseawq@huawei.com
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