draft-ietf-xrblock-rtcp-xr-burst-gap-discard-04.txt   draft-ietf-xrblock-rtcp-xr-burst-gap-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: January 11, 2013 Telchemy Expires: January 31, 2013 Telchemy
R. Huang R. Huang
Q. Wu, Ed. Q. Wu, Ed.
Huawei Huawei
July 10, 2012 July 30, 2012
RTCP XR Report Block for Burst/Gap Discard metric Reporting RTCP XR Report Block for Burst/Gap Discard metric Reporting
draft-ietf-xrblock-rtcp-xr-burst-gap-discard-04.txt draft-ietf-xrblock-rtcp-xr-burst-gap-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 Burst and Gap Discard metrics for use in a range of RTP reporting of Burst and Gap Discard metrics 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-
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 January 11, 2013. This Internet-Draft will expire on January 31, 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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However the metric in [DISCARD] may be used independently of the However the metric in [DISCARD] may be used independently of the
metrics in this block. metrics in this block.
This block provides information on transient IP problems. Burst/Gap This block provides information on transient IP problems. Burst/Gap
metrics are typically used in Cumulative reports however MAY be used metrics are typically used in Cumulative reports however MAY be used
in Interval reports. The burstiness of packet discard affects user in Interval reports. The burstiness of packet discard affects user
experience, may influence any sender strategies to mitigate the experience, may influence any sender strategies to mitigate the
problem, and may also have diagnostic value. problem, and may also have diagnostic value.
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] . defined in [MONARCH].
The definitions of Burst, Gap, Loss and Discard are consistent with The definitions of Burst, Gap, Loss and Discard are consistent with
definitions in [RFC3611]. To accommodate the range of jitter buffer definitions in [RFC3611]. To accommodate the range of jitter buffer
algorithms and packet discard logic that may be used by implementors, algorithms and packet discard logic that may be used by implementors,
the method used to distinguish between bursts and gaps may be an the method used to distinguish between bursts and gaps may be an
equivalent method to that defined in[RFC3611] . equivalent method to that defined in[RFC3611].
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. The Report (XR). This document defines a new Extended Report block. The
use of Extended Report blocks is defined by [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. Metrics definition and specification of performance metrics. Metrics
described in this draft either reference external definitions or described in this draft either reference external definitions or
define metrics generally in accordance with the guidelines in define metrics generally in accordance with the guidelines in
[RFC6390]. [RFC6390].
1.4. Applicability 1.4. Applicability
These metrics are applicable to a range of RTP applications. These metrics are applicable to a range of RTP applications which
don't use stream repair means.
2. Terminology 2. Terminology
2.1. Standards Language 2.1. Standards Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"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. one of received (or OK), discarded or lost. The metric
"cumulative number of packets lost" defined in [RFC3550] reports a
count of packets lost from the media stream (single SSRC within
single RTP session). Similarly the metric "number of packets
discarded" defined in [DISCARD] reports a count of packets
discarded from the media stream (single SSRC within single RTP
session) arriving at the receiver. Another metric defined in
[RFC5725] is available to report on packets which are not
recovered by any repair techniques which may be in use.
Bursts and Gaps Bursts and Gaps
The terms Burst and Gap are used in a manner consistent with that The terms Burst and Gap are used in a manner consistent with that
of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided of RTCP XR [RFC3611]. RTCP XR views a RTP stream as being divided
into bursts, which are periods during which the discard rate is into bursts, which are periods during which the discard rate is
high enough to cause noticeable quality degradation (generally high enough to cause noticeable quality degradation (generally
over 5 percent discard rate), and gaps, which are periods during over 5 percent discard rate), and gaps, which are periods during
which discarded packets are infrequent and hence quality is which discarded packets are infrequent and hence quality is
generally acceptable. generally acceptable.
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Burst/Gap Discard metrics block Burst/Gap Discard metrics block
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=NBGD | I | resv. | block length = 3 | | BT=NBGD | I | resv. | block length = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source | | SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Threshold | Packets Discarded in Bursts | | Threshold | Packets Discarded in Bursts |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Total Packets expected in bursts | Reserved. | | Total Packets expected in bursts | Reserved. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure Figure 1: Report Block Structure
3.2. Definition of Fields in Burst/Gap Discard Report Block 3.2. Definition of Fields in Burst/Gap Discard Report Block
Block type (BT): 8 bits Block type (BT): 8 bits
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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 Burst/Gap Discard This field is used to indicate whether the Burst/Gap Discard
metrics are Sampled, Interval or Cumulative metrics, that is, metrics are Sampled, Interval or Cumulative metrics, that is,
whether 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). sampled instantaneous value (I=01) (Sampled Value). In this
document, Burst/Gap Discard Metric is not measured at a particular
time instant but over one or several reporting intervals.
Therefore Burst/Gap Discard Metric MUST NOT be chosen as Sampled
Metric.
Reserved (resv): 6 bits Reserved (resv): 6 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 3. the Burst/Gap discard block, the block length is equal to 3.
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].
Threshold: 8 bits Threshold: 8 bits
The Threshold is equivalent to Gmin in [RFC3611], i.e. the number The Threshold is equivalent to Gmin in [RFC3611], i.e. the number
of successive packets that must not be discarded prior to and of successive packets that must not be discarded prior to and
following a discard packet in order for this discarded packet to following a discard packet in order for this discarded packet to
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o The fraction of packets discarded during gaps (gap discard rate in o The fraction of packets discarded during gaps (gap discard rate in
[SUMSTAT]) [SUMSTAT])
The details on calculation these parameters in the metrics are The details on calculation these parameters in the metrics are
described in [SUMSTAT]. described in [SUMSTAT].
4. Considerations for Voice-over-IP applications 4. Considerations for Voice-over-IP applications
This metric block is applicable to a broad range of RTP applications. This metric block is applicable to a broad range of RTP applications.
Where the metric is used with a Voice-overIP (VoIP) application, the Where the metric is used with a Voice-overIP (VoIP) application and
following considerations apply. the stream repair means is not available, the following
considerations apply.
RTCP XR views a call as being divided into bursts, which are periods RTCP XR views a call as being divided into bursts, which are periods
during which the discard rate is high enough to cause noticeable call during which the discard rate is high enough to cause noticeable call
quality degradation (generally over 5 percent discard rate), and quality degradation (generally over 5 percent discard rate), and
gaps, which are periods during which discarded packets are infrequent gaps, which are periods during which discarded packets are infrequent
and hence call quality is generally acceptable. and hence call quality is generally acceptable.
If Voice Activity Detection is used the Burst and Gap Duration shall If Voice Activity Detection is used the Burst and Gap Duration shall
be determined as if silence packets had been sent, i.e. a period of be determined as if silence packets had been sent, i.e. a period of
silence in excess of Gmin packets MUST terminate a burst condition. silence in excess of Gmin packets MUST terminate a burst condition.
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[RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003. Applications", RFC 3550, July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", November 2003. Protocol Extended Reports (RTCP XR)", November 2003.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", July 2006. Description Protocol", July 2006.
[RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE
Report Block Type for RTP Control Protocol (RTCP) Extended
Reports (XRs)", RFC 5725, February 2020.
9.2. Informative References 9.2. Informative References
[DISCARD] Hunt, G., "RTCP XR Report Block for Discard metric [DISCARD] Hunt, G., "RTCP XR Report Block for Discard metric
Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-02, Reporting", ID draft-ietf-xrblock-rtcp-xr-discard-05,
April 2012. July 2012.
[MEASID] Wu, Q., "Measurement Identity and information Reporting [MEASID] Wu, Q., "Measurement Identity and information Reporting
using SDES item and XR Block", using SDES item and XR Block",
ID draft-ietf-xrblock-rtcp-xr-meas-identity-05, ID draft-ietf-xrblock-rtcp-xr-meas-identity-09, July 2012.
April 2012.
[MONARCH] Hunt, G., "Monitoring Architectures for RTP", [MONARCH] Hunt, G., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-12, April 2012. ID draft-ietf-avtcore-monarch-12, June 2012.
[PSES] "URL", http://www.its.bldrdoc.gov/projects/devglossary/ [PSES] "URL", http://www.its.bldrdoc.gov/projects/devglossary/
_severely_errored_second.html, October 2011. _severely_errored_second.html, October 2011.
[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.
[SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics [SUMSTAT] Zorn, G., "RTCP XR for Summary Statistics Metrics
Reporting", ID draft-zorn-xrblock-rtcp-xr-al-stat-05, Reporting", ID draft-zorn-xrblock-rtcp-xr-al-stat-06,
February 2012. July 2012.
Authors' Addresses Authors' Addresses
Geoff Hunt Geoff Hunt
Unaffiliated Unaffiliated
Email: r.geoff.hunt@gmail.com Email: r.geoff.hunt@gmail.com
Alan Clark Alan Clark
Telchemy Incorporated Telchemy Incorporated
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