| 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
This document defines RTCP SDES items carrying parameters which identify a measurement, to which one or more other RTCP XR Report Blocks may refer.
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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
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.
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.
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).
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.
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.
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.
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.
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.
New SDES types for RTCP SDES are subject to IANA registration. For general guidelines on IANA considerations for RTCP SDES, refer to [RFC3550].
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
This document assigns additional five SDES types in the IANA "RTCP XR Block Type Registry" to the Measurement Identity SDES items as follow:
[Note to RFC Editor: please replace APSI,EXF,EXLS,CUMD,INMD with the IANA provided RTCP SDES type for these SDES items.]
This document also registers a new parameter "jitter-bfr" in the "RTCP XR SDP Parameters Registry".
The contact information for the registrations is: Qin Wu (sunseawq@huawei.com) 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China
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.
| [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. |
| [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. |
Note to the RFC-Editor: please remove this section prior to publication as an RFC.
The following are the major changes to draft-ietf-avt-rtcp-xr-meas-identity-02: