draft-ietf-xrblock-rtcp-xr-discard-09.txt   draft-ietf-xrblock-rtcp-xr-discard-10.txt 
Audio/Video Transport Working Group A. Clark Audio/Video Transport Working Group A. Clark
Internet-Draft Telchemy Internet-Draft Telchemy
Intended status: Standards Track G. Zorn Intended status: Standards Track G. Zorn
Expires: April 15, 2013 Network Zen Expires: June 17, 2013 Network Zen
Q. Wu Q. Wu
Huawei Huawei
October 12, 2012 December 14, 2012
RTP Control Protocol (RTCP) Extended Report (XR) Block for Discard Count RTP Control Protocol (RTCP) Extended Report (XR) Block for Discard Count
metric Reporting metric Reporting
draft-ietf-xrblock-rtcp-xr-discard-09.txt draft-ietf-xrblock-rtcp-xr-discard-10.txt
Abstract Abstract
This document defines an RTP Control Protocol(RTCP) Extended Report This document defines an RTP Control Protocol(RTCP) Extended Report
(XR) Block that allows the reporting of a simple discard count metric (XR) Block that allows the reporting of a simple discard count metric
for use in a range of RTP applications. for use in a range of RTP applications.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 15, 2013. This Internet-Draft will expire on June 17, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 10 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 10
5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10
5.3. Contact information for registrations . . . . . . . . . . 10 5.3. Contact information for registrations . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . . 14 9.1. Normative References . . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . . 14 9.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 15 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 15
A.1. draft-ietf-xrblock-rtcp-xr-discard-09 . . . . . . . . . . 15 A.1. draft-ietf-xrblock-rtcp-xr-discard-10 . . . . . . . . . . 15
A.2. draft-ietf-xrblock-rtcp-xr-discard-08 . . . . . . . . . . 15 A.2. draft-ietf-xrblock-rtcp-xr-discard-09 . . . . . . . . . . 15
A.3. draft-ietf-xrblock-rtcp-xr-discard-08 . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
1.1. Discard Count Report Block 1.1. Discard Count Report Block
This document defines a new block type to augment those defined in This document defines a new block type to augment those defined in
[RFC3611] for use in a range of RTP applications. The new block type [RFC3611] for use in a range of RTP applications. The new block type
supports the reporting of the number of packets which are received supports the reporting of the number of packets which are received
correctly but are never played out, typically because they arrive too correctly but are never played out, typically because they arrive too
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this block. this block.
In case of Discard count metric block sent together with Burst gap In case of Discard count metric block sent together with Burst gap
discard metric block defined in [BGDISCARD] to the media sender or discard metric block defined in [BGDISCARD] to the media sender or
RTP based network management system, information carried in the RTP based network management system, information carried in the
discard count metric block and Burst gap discard metric block allows discard count metric block and Burst gap discard metric block allows
them calculate the some bust gap summary statistics, e.g., gap them calculate the some bust gap summary statistics, e.g., gap
discard rate. discard rate.
The metric belongs to the class of transport-related end system The metric belongs to the class of transport-related end system
metrics defined in [MONARCH]. metrics defined in [RFC6792].
1.2. RTCP and RTCP XR Reports 1.2. RTCP and RTCP XR Reports
The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] The use of RTCP for reporting is defined in [RFC3550]. [RFC3611]
defined an extensible structure for reporting using an RTCP Extended defined an extensible structure for reporting using an RTCP Extended
Report (XR). This document defines a new Extended Report block for Report (XR). This document defines a new Extended Report block for
use with [RFC3550] and [RFC3611]. use with [RFC3550] and [RFC3611].
1.3. Performance Metrics Framework 1.3. Performance Metrics Framework
The Performance Metrics Framework [RFC6390] provides guidance on the The Performance Metrics Framework [RFC6390] provides guidance on the
definition and specification of performance metrics. The RTP definition and specification of performance metrics. The RTP
Monitoring Architectures [MONARCH] provides guideline for reporting Monitoring Architectures [RFC6792] provides guideline for reporting
block format using RTCP XR. The Metrics Block described in this block format using RTCP XR. The Metrics Block described in this
document are in accordance with the guidelines in [RFC6390] and document are in accordance with the guidelines in [RFC6390] and
[MONARCH]. [RFC6792].
1.4. Applicability 1.4. Applicability
This metric is believed to be applicable to a large class of RTP This metric is believed to be applicable to a large class of RTP
applications which use a jitter buffer. applications which use a jitter buffer.
Discards due to late or early arriving packets affects user Discards due to late or early arriving packets affects user
experience. The reporting of discards alerts senders and other experience. The reporting of discards alerts senders and other
receivers to the need to adjust their transmission or reception receivers to the need to adjust their transmission or reception
strategies. The reports allow network managers to diagnose these strategies. The reports allow network managers to diagnose these
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packets lost from the media stream (single SSRC within single RTP packets lost from the media stream (single SSRC within single RTP
session). Similarly the metric "number of packets discarded" session). Similarly the metric "number of packets discarded"
reports a count of packets discarded from the media stream (single reports a count of packets discarded from the media stream (single
SSRC within single RTP session) arriving at the receiver. Another SSRC within single RTP session) arriving at the receiver. Another
metric defined in [RFC5725] is available to report on packets metric defined in [RFC5725] is available to report on packets
which are not recovered by any repair techniques which may be in which are not recovered by any repair techniques which may be in
use. use.
3. Discard Count Metric Report Block 3. Discard Count Metric Report Block
Metrics in this block report on the number of packets discarded in
the stream arriving at the RTP end system. The measurement of these
metrics is made at the receiving end of the RTP stream. Instances of
this Metrics Block refer by SSRC to the separate auxiliary
Measurement Information block [RFC6776] which contains measurement
intervals. This metric block relies on the measurement interval in
the Measurement Information block indicating the span of the report
and should be sent in the same compound RTCP packet as the
measurement information block. If the measurement interval is not
received in the same compound RTCP packet as this metric block, this
metric block should be discarded.
3.1. Report Block Structure 3.1. Report Block Structure
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=PDC | I |DT | resv.| block length = 2 | | BT=PDC | I |DT | resv.| block length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source | | SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| number of packets discarded | | number of packets discarded |
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3.2. Definition of Fields in Discard Count Metric Report Block 3.2. Definition of Fields in Discard Count Metric Report Block
Block type (BT): 8 bits Block type (BT): 8 bits
A Discard Count Metric Report Block is identified by the constant A Discard Count Metric Report Block is identified by the constant
PDC. PDC.
[Note to RFC Editor: please replace PDC with the IANA provided [Note to RFC Editor: please replace PDC with the IANA provided
RTCP XR block type for this block.] RTCP XR block type for this block.]
Interval Metric flag (I): 2 bits Interval Metric Flag (I): 2 bits
This field indicates whether the reported metric is an interval, This field indicates whether the reported metric is an interval,
cumulative, or sampled metric [MONARCH]. The Discard Count Metric cumulative, or sampled metric [RFC6792]. The Discard Count Metric
value can be reported as either an interval metric (I=10) or a can only be measured over definite intervals, and cannot be
cumulative metric (I=11). It does not make sense to report the sampled. Accordingly, the value I=01, indicating a sampled value,
Discard Count Metric as a sampled metric, so the value I=01 MUST MUST NOT be used. The value I=00 is reserved for future
NOT be used. The value I=00 is reserved, and MUST NOT be used. definition, and MUST NOT be used.
Discard Type (DT): 2bits Discard Type (DT): 2bits
This field is used to identify the discard type used in this This field is used to identify the discard type used in this
report block. The discard type is defined as follows: report block. The discard type is defined as follows:
00: Report packet discarded or being thrown away before playout 00: Report packet discarded or being thrown away before playout
due to packets duplication. due to packets duplication.
01: Report packet discarded due to too early to be played out. 01: Report packet discarded due to too early to be played out.
10: Report packet discarded due to too late to be played out. 10: Report packet discarded due to too late to be played out.
11: Report the total number of discarded packets due to both The value DT=11 is reserved for future definition and MUST NOT be
early and late to be played out. used.
An endpoint MAY report only one of the above four discard types An endpoint MAY report only one of the above three discard types
blocks in an compound RTCP report in a reporting interval. It MAY blocks in an compound RTCP report in a reporting interval. It MAY
also report a combination of discard types in a compound RTCP also report a combination of any two discard types in a compound
report but not all combinations are valid. The endpoint MAY RTCP report. The endpoint MAY report duplicate packet discard
report duplicate packet discard (DT=0) block with any other (DT=0) block with the other two discard (DT=1, 2) blocks.
discard (DT=1, 2, or 3) block. Additionally, an endpoint MUST NOT
report combined discard (DT=3) block with early discard (DT=1) or
late discard (DT=2) report block.
Some systems send duplicate RTP packets for robustness or error Some systems send duplicate RTP packets for robustness or error
resilience. This is NOT RECOMMENDED since it breaks RTCP packet resilience. This is NOT RECOMMENDED since it breaks RTCP packet
statistics. If duplication is desired for error resilience, the statistics. If duplication is desired for error resilience, the
mechanism described in [RTPDUP] can be used, since this will not mechanism described in [RTPDUP] can be used, since this will not
cause breakage of RTP streams or RTCP statistics. cause breakage of RTP streams or RTCP statistics.
Reserved (resv): 4 bits Reserved (resv): 4 bits
These bits are reserved. They MUST be set to zero by senders and These bits are reserved. They MUST be set to zero by senders and
ignored by receivers. ignored by receivers.
block length: 16 bits block length: 16 bits
The length of this report block in 32-bit words, minus one. For The length of this report block in 32-bit words, minus one and
the Discard Count block, the block length is equal to 2. MUST be set to 2,, in accordance with the definition of this field
in [RFC3611]. The block MUST be discarded if the block length is
set to a different value.
SSRC of source: 32 bits SSRC of source: 32 bits
As defined in Section 4.1 of [RFC3611]. As defined in Section 4.1 of [RFC3611].
number of packets discarded: 32 bits number of packets discarded: 32 bits
Number of packets discarded over the period (Interval or Number of packets discarded over the period (Interval or
Cumulative) covered by this report. Cumulative) covered by this report.
If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE If the measured value exceeds 0xFFFFFFFD, the value 0xFFFFFFFE
MUST be reported to indicate an over-range measurement. If the MUST be reported to indicate an over-range measurement. If the
measurement is unavailable, the value 0xFFFFFFFF MUST be reported. measurement is unavailable, the value 0xFFFFFFFF MUST be reported.
Note that the number of packets expected in the period associated Note that the number of packets expected in the period associated
with this metric (whether interval or cumulative) is available with this metric (whether interval or cumulative) is available
from the difference between a pair of extended sequence numbers in from the difference between a pair of extended sequence numbers in
the Measurement Information block [MEASI], so need not be repeated the Measurement Information block [RFC6776], so need not be
in this block. repeated in this block.
4. SDP Signaling 4. SDP Signaling
[RFC3611] defines the use of SDP (Session Description Protocol) [RFC3611] defines the use of SDP (Session Description Protocol)
[RFC4566] for signaling the use of XR blocks. XR blocks MAY be used [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used
without prior signaling. without prior signaling.
4.1. SDP rtcp-xr-attrib Attribute Extension 4.1. SDP rtcp-xr-attrib Attribute Extension
This section augments the SDP [RFC4566] attribute "rtcp-xr" defined This section augments the SDP [RFC4566] attribute "rtcp-xr" defined
in [RFC3611] by providing an additional value of "xr-format" to in [RFC3611] by providing an additional value of "xr-format" to
signal the use of the report block defined in this document. signal the use of the report block defined in this document.
xr-format =/ xr-pdc-block xr-format =/ xr-pdc-block
xr-pdc-block = "pkt-dscrd-count" xr-pdc-block = "pkt-dscrd-count"
4.2. Offer/Answer Usage 4.2. Offer/Answer Usage
When SDP is used in offer-answer context, the SDP Offer/Answer usage When SDP is used in offer-answer context, the SDP Offer/Answer usage
defined in [RFC3611] applies. defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters
applies. For detailed usage in Offer/Answer for unilateral
parameter, refer to section 5.2 of [RFC3611].
5. IANA Considerations 5. IANA Considerations
New block types for RTCP XR are subject to IANA registration. For New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to general guidelines on IANA considerations for RTCP XR, refer to
[RFC3611]. [RFC3611].
5.1. New RTCP XR Block Type value 5.1. New RTCP XR Block Type value
This document assigns the block type value PDC in the IANA "RTCP XR This document assigns the block type value PDC in the IANA "RTCP XR
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Description Protocol", July 2006. Description Protocol", July 2006.
9.2. Informative References 9.2. Informative References
[BGDISCARD] [BGDISCARD]
Hunt, G., "RTCP XR Report Block for Burst Gap Discard Hunt, G., "RTCP XR Report Block for Burst Gap Discard
metric Reporting", metric Reporting",
ID draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06, ID draft-ietf-xrblock-rtcp-xr-burst-gap-discard-06,
October 2012. October 2012.
[MEASI] Hunt, G., "Measurement Identity and information Reporting
using SDES item and XR Block",
ID draft-ietf-xrblock-rtcp-xr-meas-identity-10,
August 2012.
[MONARCH] Wu, Q., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-22, September 2012.
[RFC4588] Rey, J., "RTP Retransmission Payload Format", RFC 4588, [RFC4588] Rey, J., "RTP Retransmission Payload Format", RFC 4588,
July 2006. July 2006.
[RFC5109] Li, A., "RTP Payload Format for Generic Forward Error [RFC5109] Li, A., "RTP Payload Format for Generic Forward Error
Correction", RFC 5109, July 2006. Correction", RFC 5109, July 2006.
[RFC5725] Begen, A., "RTCP XR Report Block for Post-Repair Loss [RFC5725] Begen, A., "RTCP XR Report Block for Post-Repair Loss
metric Reporting", RFC 5725, February 2010. metric Reporting", RFC 5725, February 2010.
[RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric
Development", RFC 6390, October 2011. Development", RFC 6390, October 2011.
[RFC6776] Hunt, G., "Measurement Identity and information Reporting
using SDES item and XR Block", RFC 6776, October 2012.
[RFC6792] Wu, Q., "Monitoring Architectures for RTP", RFC 6792,
November 2012.
[RTPDUP] Begen, A. and C. Perkins, "Duplicating RTP Streams", [RTPDUP] Begen, A. and C. Perkins, "Duplicating RTP Streams",
ID draft-ietf-avtext-rtp-duplication-00, July 2012. ID draft-ietf-avtext-rtp-duplication-00, July 2012.
Appendix A. Change Log Appendix A. Change Log
Note to the RFC-Editor: please remove this section prior to Note to the RFC-Editor: please remove this section prior to
publication as an RFC. publication as an RFC.
A.1. draft-ietf-xrblock-rtcp-xr-discard-09 A.1. draft-ietf-xrblock-rtcp-xr-discard-10
The following are the major changes compared to previous version:
o Editorial change to get in line with recently discussed drafts.
o Remove DT=3 based on the discussion to summary statistics draft.
A.2. draft-ietf-xrblock-rtcp-xr-discard-09
The following are the major changes compared to previous version: The following are the major changes compared to previous version:
o SDP Duplicated Parameter Deleting. o SDP Duplicated Parameter Deleting.
A.2. draft-ietf-xrblock-rtcp-xr-discard-08 A.3. draft-ietf-xrblock-rtcp-xr-discard-08
The following are the major changes compared to previous version: The following are the major changes compared to previous version:
o Outdated reference update. o Outdated reference update.
o Editorial changes based on comments that applied to PDV and Delay o Editorial changes based on comments that applied to PDV and Delay
drafts. drafts.
Authors' Addresses Authors' Addresses
 End of changes. 21 change blocks. 
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