draft-ietf-xrblock-rtcp-xr-discard-04.txt   draft-ietf-xrblock-rtcp-xr-discard-05.txt 
Audio/Video Transport Working Group G. Hunt Audio/Video Transport Working Group G. Hunt
Internet-Draft Unaffiliated Internet-Draft Unaffiliated
Intended status: Standards Track A. Clark Intended status: Standards Track A. Clark
Expires: December 31, 2012 Telchemy Expires: January 11, 2013 Telchemy
G. Zorn G. Zorn
Network Zen Network Zen
Q. Wu Q. Wu
Huawei Huawei
June 29, 2012 July 10, 2012
RTCP XR Report Block for Discard Count metric Reporting RTCP XR Report Block for Discard Count metric Reporting
draft-ietf-xrblock-rtcp-xr-discard-04.txt draft-ietf-xrblock-rtcp-xr-discard-05.txt
Abstract Abstract
This document defines an RTCP XR Report Block that allows the This document defines an RTCP XR Report Block that allows the
reporting of a simple discard count metric for use in a range of RTP reporting of a simple discard count metric for use in a range of RTP
applications. 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-
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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 December 31, 2012. This Internet-Draft will expire on January 11, 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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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Discard Count Report Block . . . . . . . . . . . . . . . . 3 1.1. Discard Count Report Block . . . . . . . . . . . . . . . . 3
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 4 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 4
3. Discard Count Metric Report Block . . . . . . . . . . . . . . 5 3. Discard Count Metric Report Block . . . . . . . . . . . . . . 5
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in Discard Metric Report Block . . . 5 3.2. Definition of Fields in Discard Count Metric Report
4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 7 Block . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 8 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 9
5.3. Contact information for registrations . . . . . . . . . . 8 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5.3. Contact information for registrations . . . . . . . . . . 9
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . . 11 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . . 11 8.1. Normative References . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
1.1. Discard Count Report Block 1.1. Discard Count Report Block
This draft 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
late to be played out (buffer underflow) or too early (buffer late to be played out (buffer underflow) or too early (buffer
overflow). The metric is applicable both to systems which use packet overflow). The metric is applicable both to systems which use packet
loss repair techniques (such as forward error correction [RFC5109] or loss repair techniques (such as forward error correction [RFC5109] or
retransmission [RFC4588]) and to those which do not. retransmission [RFC4588]) and to those which do not.
This metric is useful for identifying the existence, and This metric is useful for identifying the existence, and
characterising the severity, of a packet transport problem which may characterising the severity, of a packet transport problem which may
affect users' perception of a service delivered over RTP. affect users' perception of a service delivered over RTP.
The metric belongs to the class of transport-related terminal metrics The metric belongs to the class of transport-related terminal metrics
defined in [MONARCH] (work in progress). defined in [MONARCH].
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 draft defines a new Extended Report block that Report (XR). This document defines a new Extended Report block. The
MUST be used as defined in [RFC3550] and [RFC3611]. use of Extended Report blocks is defined by [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 [MONARCH] 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]. [MONARCH].
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
In addition, the following terms are defined: In addition, the following terms are defined:
Received, Lost and Discarded Received, Lost and Discarded
A packet shall be regarded as lost if it fails to arrive within an A packet shall be regarded as lost if it fails to arrive within an
implementation-specific time window. A packet that arrives within implementation-specific time window. A packet that arrives within
this time window but is too early or late to be played out or this time window but is too early or late to be played out or
thrown away before playout (e.g., packet duplication or thrown away before playout due to packet duplication or redundancy
redundancy) shall be regarded as discarded. A packet shall be shall be regarded as discarded. A packet shall be classified as
classified as one of received (or OK), discarded or lost. The one of received (or OK), discarded or lost. The Discard Count
Discard Count Metric counts only discarded packets. The metric Metric counts only discarded packets. The metric "cumulative
"cumulative number of packets lost" defined in [RFC3550] reports a number of packets lost" defined in [RFC3550] reports a count of
count of packets lost from the media stream (single SSRC within packets lost from the media stream (single SSRC within single RTP
single RTP session). Similarly the metric "number of packets session). Similarly the metric "number of packets discarded"
discarded" reports a count of packets discarded from the media reports a count of packets discarded from the media stream (single
stream (single SSRC within single RTP session) arriving at the SSRC within single RTP session) arriving at the receiver. Another
receiver. Another metric defined in [RFC5725] is available to metric defined in [RFC5725] is available to report on packets
report on packets which are not recovered by any repair techniques which are not recovered by any repair techniques which may be in
which may be in use. use.
3. Discard Count Metric Report Block 3. Discard Count Metric Report Block
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 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 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=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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure Figure 1: Report Block Structure
3.2. Definition of Fields in Discard 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 is used to indicate whether the Discard Count Metric is This field is used to indicate whether the Discard Count Metric is
an Interval or Cumulative metric, Sample metric,that is, whether an Interval or Cumulative metric, Sample metric [MONARCH],that is,
the reported values applies to the most recent measurement whether the reported values applies to the most recent measurement
interval duration between successive metrics reports (I=10) (the interval duration between successive metrics reports (I=10) (the
Interval Duration) or to the accumulation period characteristic of Interval Duration) or to the accumulation period characteristic of
cumulative measurements (I=11) (the Cumulative Duration) or is a cumulative measurements (I=11) (the Cumulative Duration) or is a
sampled instantaneous value (I=01) (Sampled Value). In this sampled instantaneous value (I=01) (Sampled Value). In this
document, Discard Count Metric is not measured at a particular document, Discard Count Metric is not measured at a particular
time instant but over one or several reporting intervals. time instant but over one or several reporting intervals.
Therefore Discard Count Metric MUST not be chosen as Sampled Therefore Discard Count Metric MUST not be chosen as Sampled
Metric. Metric.
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 due to too early to be played out. 00: Report packet discarded or being thrown away before playout
due to packets duplication.
01: Report packet discarded due to too late to be played out. 01: Report packet discarded due to too early to be played out.
10: Report packet discarded due to both early and late to be 10: Report packet discarded due to too late to be played out.
played out.
11: Report the total number of discarded packets in the 11: Report the total number of discarded packets due to both
interval. The reasons to discard packet include too early to early and late to be played out.
be played out, too late to be playout,being thrown away before
playout.
Reserved (resv): 5 bits An endpoint MAY send only one of the discard types (early, late,
duplication packets discard) in one RTCP report or choose to
report early (DT=1) and late (DT=2), duplication packets discard
(DT=0) in separate block. It MAY also send the combined early and
late discard type (DT=2) in one RTCP compound packet, but not any
other combination of the three Discard Types. The endpoint MUST
not report the the total number of discarded packets covering all
three discard types. Instead, two separate report blocks should
be used to carry duplication packets discard and the combined
early and late discard respectively.
Reserved (resv): 4 bits
These bits are reserved. They SHOULD be set to zero by senders These bits are reserved. They SHOULD be set to zero by senders
and MUST be ignored by receivers. and MUST be 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. For
the Delay block, the block length is equal to 2. the Discard Count block, the block length is equal to 2.
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 covered by Note that the number of packets expected in the period associated
the metric (whether interval or cumulative) is available from the with this metric (whether interval or cumulative) is available
difference between a pair of extended sequence numbers in the from the difference between a pair of extended sequence numbers in
Measurement Information block [MEASI], so need not be repeated in the Measurement Information block [MEASI], so need not be repeated
this block. 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.
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.
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5.2. New RTCP XR SDP Parameter 5.2. New RTCP XR SDP Parameter
This document also registers a new parameter "pkt-dscrd" in the "RTCP This document also registers a new parameter "pkt-dscrd" in the "RTCP
XR SDP Parameters Registry". XR SDP Parameters Registry".
5.3. Contact information for registrations 5.3. Contact information for registrations
The following contact information is provided for all The following contact information is provided for all
registrations in this document: registrations in this document:
Geoff Hunt (r.geoff.hunt@gmail.com) Qin Wu (sunseawq@huawei.com)
Orion 2 PP3, Adastral Park, Martlesham Heath, Ipswich IP5 3RE, United 101 Software Avenue, Yuhua District
Kingdom Nanjing, Jiangsu 210012
China
6. Security Considerations 6. Security Considerations
It is believed that this proposed RTCP XR report block introduces no It is believed that this proposed RTCP XR report block introduces no
new security considerations beyond those described in [RFC3611]. new security considerations beyond those described in [RFC3611].
This block does not provide per-packet statistics so the risk to This block does not provide per-packet statistics so the risk to
confidentiality documented in Section 7, paragraph 3 of [RFC3611] confidentiality documented in Section 7, paragraph 3 of [RFC3611]
does not apply. does not apply.
7. Acknowledgments 7. Acknowledgments
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