wdiff rfc7002.original rfc7002.txt

Audio/Video Transport Working Group
Internet Engineering Task Force (IETF) A. Clark
Internet-Draft
Request for Comments: 7002 Telchemy
Intended status:
Category: Standards Track G. Zorn
Expires: December 30, 2013
ISSN: 2070-1721 Network Zen
Q. Wu
Huawei
June 28,
September 2013

RTP Control Protocol (RTCP) Extended Report (XR) Block
for Discard Count
metric Metric Reporting
draft-ietf-xrblock-rtcp-xr-discard-15.txt

Abstract

This document defines an RTP Control Protocol(RTCP) Protocol (RTCP) Extended Report
(XR) Block block that allows the reporting of a simple discard count metric
for use in a range of RTP applications.

Status of this This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
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Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of six months this document, any errata,
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material or to cite them other than as "work in progress."

This Internet-Draft will expire on December 30, 2013.
http://www.rfc-editor.org/info/rfc7002.

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Provisions Relating to IETF Documents
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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2
1.1. Discard Count Report Block . . . . . . . . . . . . . . . . 3 2
1.2. RTCP and RTCP XR Extended Reports . . . . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 5 3
3. Discard Count Metric Report Metrics Block . . . . . . . . . . . . . . 6 . . . 4
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 6 5
3.2. Definition of Fields in the Discard Count Metric Report Metrics Block . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5
4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9 7
4.1. SDP rtcp-xr-attrib rtcp-xr Attribute Extension . . . . . . . . . . 9 . . . 7
4.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 9 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 7
5.1. New RTCP XR Block Type value . Value . . . . . . . . . . . . . . 10 8
5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 10 8
5.3. Contact information Information for registrations Registrations . . . . . . . . . . 10 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 8
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12 8
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9
9.1. Normative References . . . . . . . . . . . . . . . . . . . 14 9
9.2. Informative References . . . . . . . . . . . . . . . . . . 14 10
Appendix A. Metrics represented using RFC6390 Represented Using the Template . . . . . 15
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 16
B.1. draft-ietf-xrblock-rtcp-xr-discard-14 . . . . . . . . . . 16
B.2. draft-ietf-xrblock-rtcp-xr-discard-13 . . . . . . . . . . 16
B.3. draft-ietf-xrblock-rtcp-xr-discard-12 . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 from RFC 6390 11

1. Introduction

1.1. Discard Count Report Block

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
supports the reporting of the number of packets which that are received
correctly but are never played out, typically because they arrive too
late to be played out (buffer underflow) or too early (buffer
overflow). overflow) to be played
out. The metric is applicable both to systems which that use packet loss
repair techniques (such as forward error correction [RFC5109] or
retransmission [RFC4588]) and to those which that do not.

This metric is useful for identifying the existence, and
characterizing the severity, of a packet transport problem which problems that may
affect users' perception perceptions of a service delivered over RTP.

This block may be used in conjunction with [BGDISCARD] [RFC7003], which provides
additional information on the pattern of discarded packets. However However,
the metric in [BGDISCARD] [RFC7003] may be used independently of the metrics in
this block.

When a Discard Count Metrics Block is sent together with a Burst Gap Burst/Gap
Discard Metrics Block (defined in [BGDISCARD] ) [RFC7003]) to the media sender or RTP based
RTP-based network management system, the information carried in the
Discard Count Metrics Block and the Burst Gap Burst/Gap Discard Metrics Block
allows systems receiving the blocks to calculate burst gap burst/gap summary
statistics (e.g., the gap discard rate).

The metric belongs to the class of transport-related end system end-system
metrics defined in [RFC6792].

1.2. RTCP and RTCP XR Extended 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 document defines a new Extended Report block for
use with [RFC3550] and [RFC3611].

1.3. Performance Metrics Framework

The

"Guidelines for Considering New Performance Metrics Framework Metric Development"
[RFC6390] provides guidance on the definition and specification of
performance metrics. The "Guidelines for Use of the RTP Monitoring Architectures
Framework" [RFC6792] provides guideline guidance for reporting block format
using RTCP XR. The metrics block described in this document are is in
accordance with the guidelines in [RFC6390] and [RFC6792].

1.4. Applicability

This metric is believed to be applicable to a large class of RTP
applications which that use a de-jitter buffer [RFC5481].

Discards due to late or early arriving packets affects affect user
experience. The reporting of discards alerts senders and other
receivers to the need to adjust their transmission or reception
strategies. The reports allow network managers to diagnose these
user experience problems.

The ability to detect duplicate packets can be used by managers to
detect network layer or sender behavior behavior, which may indicate network
or device issues. Based on the reports, these issues may be
addressed prior to any impact on user experience.

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].

In addition, the following terms are defined:

Received, Lost Lost, and Discarded

A packet shall be regarded as lost if it fails to arrive within an
implementation-specific time window. A packet that arrives within
this time window but is either too early to be played out or too late to be played
out or is thrown away before playout due to packet duplication or
redundancy shall be regarded as discarded. A packet shall not be
regarded as discarded if it arrives within this time window but is
dropped during decoding by some higher layer decoder, e.g., due to
a decoding error. A packet shall be classified as one of the
following: received (or OK), discarded discarded, or lost. The
Discard Count Metric discard
count metric counts only discarded packets. The metric
"cumulative number of packets lost" defined in [RFC3550] reports a
count of packets lost from the media stream (single
Synchronization
synchronization source (SSRC) within a single RTP session).
Similarly
Similarly, the metric "number of packets discarded" reports a
count of packets discarded from the media stream (single SSRC
within a single RTP session) arriving at the receiver. Another
metric defined in [RFC5725] is available to report on packets which that
are not recovered by any repair techniques which that may be in use.

3. Discard Count Metric Report Metrics 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 use the SSRC to refer to the separate auxiliary
Measurement Information Block [RFC6776] [RFC6776], which describes measurement
Intervals
periods in use. use (see [RFC6776], Section 4.2). This metrics block
relies on the measurement interval in the Measurement Information
Block indicating the span of the report and MUST be sent in the same
compound RTCP packet as the
measurement information block. Measurement Information Block. If the
measurement interval is not received in the same compound RTCP packet
as this metrics block, this metrics block MUST be discarded.

3.1. Report Block Structure

The structure of the Discard Count Metrics Block is as follows.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=PDC BT=24 | I |DT | resv.| block length resv | Block Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| discard count Discard Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 1: Report Block Structure

3.2. Definition of Fields in the Discard Count Metric Report Metrics Block

Block type Type (BT): 8 bits

A Discard Count Metric Report Metrics Block is identified by the constant
PDC.

[Note to RFC Editor: please replace PDC with the IANA provided
RTCP XR block type for this block.] 24.

Interval Metric Flag flag (I): 2 bits

This field indicates whether the reported metric is an interval,
cumulative, Interval,
Cumulative, or sampled Sampled metric [RFC6792]:

I=10: Interval Duration - the reported value applies to the
most recent measurement interval duration between successive
metrics reports.

I=11: Cumulative Duration - the reported value applies to the
accumulation period characteristic of cumulative measurements.

I=01: Sampled Value - the reported value is a sampled
instantaneous value.

In this document, the Discard Count Metric discard count metric can only be measured
over definite intervals, intervals and cannot be sampled. Accordingly, the
value I=01, indicating a sampled value, MUST NOT be sent, and MUST
be discarded when received. In addition, the value I=00 is
reserved and also MUST NOT be sent, and MUST be discarded when
received.

Discard Type (DT): 2bits 2 bits

This field is used to identify the discard type used in this
report block. The discard type is defined as follows:

00: Report packet discarded or being thrown away before playout
due to packets packet duplication.

01: Report packet discarded due to too early to be played out.

10: Report packet discarded due to too late to be played out.

The value DT=11 is reserved for future definition and MUST NOT be
Sent,and
sent, and MUST be discarded when received.

An endpoint MAY report any combination of discard types in each
reporting interval by including several Discard Count Metric
Report Metrics
Blocks in a single RTCP XR packet.

Some systems send duplicate RTP packets for robustness or error
resilience. This is NOT RECOMMENDED since it breaks RTCP packet
statistics. If duplication is desired for error resilience, the
mechanism described in [RTPDUP] can be used, since this will not
cause breakage of RTP streams or RTCP statistics.

Reserved (resv): 4 bits

These bits are reserved. They MUST be set to zero by senders and
ignored by receivers (See RFC6709 section (see [RFC6709], Section 4.2).

block length:

Block Length: 16 bits

The length of this report block in 32-bit words, minus one, in
accordance with the definition in [RFC3611]. This field MUST be
set to 2 to match the fixed length of the report block. The block
MUST be discarded if the block length is set to a different value.

SSRC of source: Source: 32 bits

As defined in Section 4.1 of [RFC3611].

discard count

Discard Count

Number of packets discarded over the period (Interval or
Cumulative) covered by this report.

The measured value is an unsigned value. If the measured value
exceeds 0xFFFFFFFD, the value 0xFFFFFFFE MUST be reported to
indicate an over-range measurement. If the measurement is
unavailable, the value 0xFFFFFFFF MUST be reported.

Note that the number of packets expected in the period associated
with this metric (whether interval Interval or cumulative) Cumulative) is available
from the difference between a pair of extended sequence numbers in
the Measurement Information block Block [RFC6776], so it need not be
repeated in this block.

4. SDP Signaling

[RFC3611] defines the use of SDP (Session the Session Description Protocol) Protocol (SDP)
[RFC4566] for signaling the use of XR blocks. However However, XR blocks MAY
be used without prior signaling (see section Section 5 of RFC3611). RFC 3611).

4.1. SDP rtcp-xr-attrib rtcp-xr Attribute Extension

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. The
ABNF [RFC5234] syntax is as follows.

xr-format =/ xr-pdc-block
xr-pdc-block = "pkt-discard-count"

4.2. Offer/Answer Usage

When SDP is used in offer-answer Offer/Answer context, the SDP Offer/Answer usage
defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters
applies. For detailed usage of Offer/Answer for unilateral
parameter,
parameters, refer to section Section 5.2 of [RFC3611].

5. 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].

5.1. New RTCP XR Block Type value Value

This document assigns the block type value PDC 24 in the IANA " RTP "RTP
Control Protocol Extended Reports (RTCP XR) Block Type Registry " Registry" to
the "Discard Count Metrics Block".

[Note to RFC Editor: please replace PDC with the IANA provided RTCP
XR block type for this block.]

5.2. New RTCP XR SDP Parameter

This document also registers a new parameter "pkt-discard-count" in
the " RTP "RTP Control Protocol Extended Reports (RTCP XR) Session
Description Protocol (SDP) Parameters Registry ". Registry".

5.3. Contact information Information for registrations Registrations

The following contact information is provided for all registrations
in this document:

Qin Wu (sunseawq@huawei.com)
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China

6. Security Considerations

In some situations, returning very detailed error information
(e.g.,over-range (e.g.,
over-range measurement or measurement unavailable) using this report
block can provide an attacker with insight into the security
processing. Where this is a concern, the implementation should apply
encryption and authentication to this report block. This For example,
this can be achieved by using the AVPF Audio-Visual Profile with Feedback
(AVPF) profile together with the Secure RTP profile profile, as defined in
[RFC3711]; as a prerequisite, an appropriate combination of those two profiles (an "SAVPF") ("SAVPF")
is being specified in [RFC5124].

Besides this, 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 statistics, so the risk to
confidentiality documented in Section 7, paragraph 3 of [RFC3611]
does not apply.

7. Contributors

Geoff Hunt wrote the initial draft of this document.

8. Acknowledgments

The authors gratefully acknowledge reviews and feedback provided by
Bruce Adams, Philip Arden, Amit Arora, Claire Bi, Bob Biskner,
Gonzalo Camarillo, Benoit Claise, Kevin Connor, Claus Dahm, Spencer
Dawkins, Randy Ethier, Roni Even, Stephen Farrel, Jim Frauenthal,
Kevin Gross, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones,
Rajesh Kumar, Keith Lantz, Jonathan Lennox, Mohamed Mostafa, Amy
Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Dan Romascanu,
Albrecht Schwarz, Tom Taylor, and Hideaki Yamada, Kevin
Gross, Varun Singh, Claire Bi, Roni Even, Tom Taylor, Dan Romascanu Wing, and Jonathan
Lennox. Hideaki
Yamada.

9. References

9.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.

[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", RFC 3611, November
2003.

[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.

[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.

[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, February 2008.

[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.

[RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design
Considerations for Protocol Extensions", RFC 6709,
September 2012.

[RFC6776] Hunt, G., Clark, A. and Q. Wu, "Measurement Identity and information Information
Reporting
using SDES item Using a Source Description (SDES) Item and XR an
RTCP Extended Report (XR) Block", RFC 6776, October 2012.

9.2. Informative References

[BGDISCARD]
Hunt, G., "RTCP XR Report Block for Burst Gap Discard
metric Reporting",
ID draft-ietf-xrblock-rtcp-xr-burst-gap-discard-14,
April 2013.

[RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R.
Hakenberg, "RTP Retransmission Payload Format", RFC 4588,
July 2006.

[RFC5109] Li, A., "RTP Payload Format for Generic Forward Error
Correction", RFC 5109, July 2006. December 2007.

[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation
Applicability Statement", RFC 5481, March 2009.

[RFC5725] Begen, A., "RTCP XR Hsu, D., and M. Lague, "Post-Repair Loss RLE
Report Block Type for Post-Repair Loss
metric Reporting", RTP Control Protocol (RTCP) Extended
Reports (XRs)", RFC 5725, February 2010.

[RFC6390] Clark, A. and B. Claise, "Framework "Guidelines for Considering New
Performance Metric Development", BCP 170, RFC 6390,
October 2011.

[RFC6792] Wu, Q., "Monitoring Architectures Hunt, G., and P. Arden, "Guidelines for RTP", Use of the
RTP Monitoring Framework", RFC 6792, November 2012.

[RFC7003] Clark, A., Huang, R., and Q. Wu, Ed., "RTP Control
Protocol(RTCP) Extended Report (XR) Block for Burst/Gap
Discard Metric Reporting", RFC 7003, September 2013.

[RTPDUP] Begen, A. and C. Perkins, "Duplicating RTP Streams",
ID draft-ietf-avtext-rtp-duplication-02, Work
in Progress, March 2013.

Appendix A. Metrics represented using RFC6390 Template

RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by Represented Using the new Template from RFC
number, when assigned. 6390

a. Number of packets discarded Packets Discarded Metric

* Metric Name: Number of RTP packets discarded Metric discarded.

* Metric Description: Number of RTP packets discarded over the
period covered by this report.

* Method of Measurement or Calculation: See section Section 3.2, number
of packets discarded definition [RFCXXXX]. Discard
Count definition.

* Units of Measurement: See section Section 3.2, number of packets
discarded definition [RFCXXXX]. Discard Count
definition.

* Measurement Point(s) with Potential Measurement Domain: See
section
Section 3, 1st paragraph [RFCXXXX]. paragraph.

* Measurement Timing: See section Section 3, 1st paragraph [RFCXXXX] for
measurement timing and section Section 3.2 [RFCXXXX] for Interval Metric flag.

* Use and applications: Applications: See section 1.4 [RFCXXXX]. Section 1.4.

* Reporting model: Model: See RFC3611.

Appendix B. Change Log

Note to the RFC-Editor: please remove this section prior to
publication as an RFC.

B.1. draft-ietf-xrblock-rtcp-xr-discard-14

The following are the major changes compared to previous version:

o Editorial changes to paragraph 4 of section 1.1.

B.2. draft-ietf-xrblock-rtcp-xr-discard-13

The following are the major changes compared to previous version:

o Some editorial changes to get in line with burst gap drafts.

B.3. draft-ietf-xrblock-rtcp-xr-discard-12

The following are the major changes compared to previous version:

o Incorporate some changes to burst gap draft that applies to this
document.

o Use RFC6390 template to the metrics in the appendix. RFC 3611.

Authors' Addresses

Alan Clark
Telchemy Incorporated
2905 Premiere Parkway, Suite 280
Duluth, GA 30097
USA

Email:

EMail: alan.d.clark@telchemy.com

Glen Zorn
Network Zen
77/440 Soi Phoomjit, Rama IV Road
Phra Khanong, Khlong Toie
227/358 Thanon Sanphawut
Bang Na, Bangkok 10110 10260
Thailand

Phone: +66 (0) 87 502 4274
Email: gwz@net-zen.net 8-1000-4155
EMail: glenzorn@gmail.com

Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China

Email:

EMail: sunseawq@huawei.com