draft-ietf-xrblock-rtcp-xr-pdv-02.txt   draft-ietf-xrblock-rtcp-xr-pdv-03.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: June 9, 2012 Telchemy Expires: November 29, 2012 Telchemy
Q. Wu Q. Wu
Huawei Huawei
December 7, 2011 May 28, 2012
RTCP XR Report Block for Packet Delay Variation Metric Reporting RTCP XR Report Block for Packet Delay Variation Metric Reporting
draft-ietf-xrblock-rtcp-xr-pdv-02.txt draft-ietf-xrblock-rtcp-xr-pdv-03.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 Packet Delay Variation metrics for a range of RTP reporting of Packet Delay Variation metrics for 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
skipping to change at page 1, line 35 skipping to change at page 1, line 35
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 June 9, 2012. This Internet-Draft will expire on November 29, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 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.
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Packet Delay Variation Metrics Block . . . . . . . . . . . 3 1.1. Packet Delay Variation Metrics 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. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 4
2.2. Notations . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Packet Delay Variation Metrics Block . . . . . . . . . . . . . 5 3. Packet Delay Variation Metrics Block . . . . . . . . . . . . . 5
3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in PDV Metrics Block . . . . . . . . 5 3.2. Definition of Fields in PDV Metrics Block . . . . . . . . 5
3.3. Guidance on use of PDV metrics . . . . . . . . . . . . . . 9 3.3. Guidance on use of PDV metrics . . . . . . . . . . . . . . 8
3.4. Examples of use . . . . . . . . . . . . . . . . . . . . . 9 3.4. Examples of use . . . . . . . . . . . . . . . . . . . . . 9
4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 11 4. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 12 5.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 12
5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 12 5.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 12
5.3. Contact information for registrations . . . . . . . . . . 12 5.3. Contact information for registrations . . . . . . . . . . 12
5.4. New registry of PDV types . . . . . . . . . . . . . . . . 12 5.4. New registry of PDV types . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.1. Normative References . . . . . . . . . . . . . . . . . . . 15 7.1. Normative References . . . . . . . . . . . . . . . . . . . 15
7.2. Informative References . . . . . . . . . . . . . . . . . . 15 7.2. Informative References . . . . . . . . . . . . . . . . . . 15
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 16 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 16
A.1. draft-ietf-avt-rtcp-xr-pdv-03 . . . . . . . . . . . . . . 16 A.1. draft-ietf-xrblock-rtcp-xr-pdv-03 . . . . . . . . . . . . 16
A.2. draft-ietf-xrblock-rtcp-xr-pdv-00 . . . . . . . . . . . . 16 A.2. draft-ietf-xrblock-rtcp-xr-pdv-02 . . . . . . . . . . . . 16
A.3. draft-ietf-xrblock-rtcp-xr-pdv-01 . . . . . . . . . . . . 16 A.3. draft-ietf-xrblock-rtcp-xr-pdv-01 . . . . . . . . . . . . 16
A.4. draft-ietf-xrblock-rtcp-xr-pdv-02 . . . . . . . . . . . . 16 A.4. draft-ietf-xrblock-rtcp-xr-pdv-00 . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 A.5. draft-ietf-avt-rtcp-xr-pdv-03 . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
1.1. Packet Delay Variation Metrics Block 1.1. Packet Delay Variation Metrics Block
This draft defines a new block type to augment those defined in This draft defines a new block type to augment those defined in
[RFC3611], for use in a range of RTP applications. [RFC3611], for use in a range of RTP applications.
The new block type provides information on Packet Delay Variation The new block type provides information on Packet Delay Variation
using one of several standard metrics. using one of several standard metrics.
The metrics belong to the class of transport metrics defined in The metrics belong to the class of transport metrics defined in
[MONARCH] (work in progress). [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 draft defines a new Extended Report block that
MUST be used in accordance with [RFC3550] and [RFC3611]. must be used in accordance 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. Metrics definition and specification of performance metrics. The RTP
described in this draft either reference external definitions or Monitoring Architectures [MONARCH] provides guideline for reporting
define metrics generally in accordance with the guidelines in block format using RTCP XR. The XR Block described in this document
[RFC6390]. are in accordance with the guidelines in [RFC6390] and [MONARCH].
1.4. Applicability 1.4. Applicability
These metrics are applicable to a range of RTP applications. These metrics are applicable to a wide range of RTP applications in
which the application streams are sensitive to delay variation
[RFC5481].
2. Definitions 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].
2.2. Notations
This report block makes use of binary fractions. The terminology This report block makes use of binary fractions. The terminology
used is used is
Numeric formats S X:Y Numeric formats S X:Y
where S indicates a two's complement signed representation, X where S indicates a two's complement signed representation, X
the number of bits prior to the decimal place and Y the number the number of bits prior to the decimal place and Y the number
of bits after the decimal place. of bits after the decimal place.
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range slightly reduces this upper limit. For example, if the range slightly reduces this upper limit. For example, if the
16- bit values 0xfffe and 0xffff are used as flags for "over- 16- bit values 0xfffe and 0xffff are used as flags for "over-
range" and "unavailable" conditions, a 0:16 quantity has range range" and "unavailable" conditions, a 0:16 quantity has range
0.0 to 1 - 3/65536 = 0.9999542 0.0 to 1 - 3/65536 = 0.9999542
3. Packet Delay Variation Metrics Block 3. Packet Delay Variation Metrics Block
Metrics in this block report on packet delay variation in the stream Metrics in this block report on packet delay variation in the stream
arriving at the RTP system. Instances of this Metrics Block refer by arriving at the RTP system. Instances of this Metrics Block refer by
SSRC to the separate auxiliary Measurement Information block [MEASI] Synchronization source (SSRC) to the separate auxiliary Measurement
which contains measurement intervals. This metric block relies on Information block [MEASI] which contains measurement intervals. This
the measurement interval in the Measurement Information block metric block relies on the measurement interval in the Measurement
indicating the span of the report. If the measurement interval is Information block indicating the span of the report and SHOULD be
not received for this metric block, this metric block should be sent in the same compound RTCP packet as the measurement information
discarded. block. If the measurement interval is not received for this metric
block, this metric block SHOULD be discarded.
3.1. Report Block Structure 3.1. Report Block Structure
PDV metrics block PDV 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=NPDV | I |pdvtyp |Rsv| block length=3 | | BT=NPDV | I |pdvtyp |Rsv| block length=3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Block type (BT): 8 bits Block type (BT): 8 bits
A Packet Delay Variation Metrics Report Block is identified by the A Packet Delay Variation Metrics Report Block is identified by the
constant NPDV. constant NPDV.
[Note to RFC Editor: please replace NPDV with the IANA provided [Note to RFC Editor: please replace NPDV with the IANA provided
RTCP XR block type for this block.] RTCP XR block type for this block.]
Interval Metric flag (I): 2 bit Interval Metric flag (I): 2 bit
This field is used to indicate whether the Basic Loss/Discard This field is used to indicate whether the Packet Delay variation
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 to the cumulative measurements (I=11) (the Cumulative Duration) or is a
value of a continuously measured or calculated that has been sampled instantaneous value (I=01) (Sampled Value).
sampled at end of the interval (I=01) (Sampled Value).
Packet Delay Variation Metric Type (pdvtyp): 4 bits Packet Delay Variation Metric Type (pdvtyp): 4 bits
This field is used to identify the Packet Delay Variation Metric Packet Delay Variation Metric Type is of type enumerated and
Type used in this report block, according to the following code: should be interpreted as Integer. This field is used to identify
the Packet Delay Variation Metric Type used in this report block,
bits 014-017 according to the following code:
0: interarrival jitter, Section 6.4.1 of [RFC3550], bits 014-011
1: MAPDV2, Clause 6.2.3.2 of [G.1020], 0: MAPDV2, Clause 6.2.3.2 of [G.1020],
2: 2-point PDV, Clause 6.2.4 of [Y.1540]. 1: 2-point PDV, Clause 6.2.4 of [Y.1540].
Rsv.: 2 bits Rsv.: 2 bits
This field is reserved for future definition. In the absence of This field is reserved for future definition. In the absence of
such a definition, the bits in this field MUST be set to zero and such a definition, the bits in this field SHOULD be set to zero
MUST be ignored by the receiver. and MUST be ignored by the receiver.
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 Packet Delay Variation Metrics block, the block length is the Packet Delay Variation Metrics block, the block length is
equal to 3. equal to 4.
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].
Positive PDV Threshold/Peak: 16 bits Positive PDV Threshold/Peak: 16 bits
This field is associated with the Positive PDV percentile and This field is associated with the Positive PDV percentile and
expressed in Milliseconds with numeric format S11:4. The term expressed in Milliseconds with numeric format S11:4. The term
Positive represents that the packets are arriving later than the Positive represents that the packets are arriving later than the
expected time. expected time.
If the measured value is more negative than -2047.9375 (the value If the measured value is more negative than -2047.9375 (the value
which would be coded as 0x8001), the value 0x8000 SHOULD be which would be coded as 0x8001), the value 0x8000 SHOULD be
reported to indicate an over-range negative measurement. If the reported to indicate an over-range negative measurement. If the
measured value is more positive than +2047.8125 (the value which measured value is more positive than +2047.8125 (the value which
would be coded as 0x7FFD), the value 0x7FFE SHOULD be reported to would be coded as 0x7FFD), the value 0x7FFE SHOULD be reported to
indicate an over-range positive measurement. If the measurement indicate an over-range positive measurement. If the measurement
is unavailable, the value 0x7FFF SHOULD be reported. is unavailable, the value 0x7FFF MUST be reported.
Positive PDV Percentile: 16 bits Positive PDV Percentile: 16 bits
The percentages of packets in the RTP stream for which individual The percentages of packets in the RTP stream for which individual
packet delays were less than the Positive PDV Threshold. It is packet delays were less than the Positive PDV Threshold. It is
expressed in numeric format 8:8 with values from 0 to 100th expressed in numeric format 8:8 with values from 0 to 100th
percentile. percentile.
If the measurement is unavailable, the value 0xFFFF SHOULD be If the measurement is unavailable, the value 0xFFFF MUST be
reported. reported.
Negative PDV Threshold/Peak: 16 bits Negative PDV Threshold/Peak: 16 bits
This field is associated with the Negative PDV percentile and This field is associated with the Negative PDV percentile and
expressed in Milliseconds with numeric format S11:4. The term expressed in Milliseconds with numeric format S11:4. The term
Negative represents that the packets are arriving earlier than the Negative represents that the packets are arriving earlier than the
expected time. expected time.
If the measured value is more negative than -2047.9375 (the value If the measured value is more negative than -2047.9375 (the value
which would be coded as 0x8001), the value 0x8000 SHOULD be which would be coded as 0x8001), the value 0x8000 SHOULD be
reported to indicate an over-range negative measurement. If the reported to indicate an over-range negative measurement. If the
measured value is more positive than +2047.8125 (the value which measured value is more positive than +2047.8125 (the value which
would be coded as 0x7FFD), the value 0x7FFE SHOULD be reported to would be coded as 0x7FFD), the value 0x7FFE SHOULD be reported to
indicate an over-range positive measurement. If the measurement indicate an over-range positive measurement. If the measurement
is unavailable, the value 0x7FFF SHOULD be reported. is unavailable, the value 0x7FFF MUST be reported.
Negative PDV Percentile: 16 bits Negative PDV Percentile: 16 bits
The percentages of packets in the RTP stream for which individual The percentages of packets in the RTP stream for which individual
packet delays were more than the Negative PDV Threshold. It is packet delays were more than the Negative PDV Threshold. It is
expressed in numeric format 8:8 with values from 0 to 100th expressed in numeric format 8:8 with values from 0 to 100th
percentile. percentile.
If the measurement is unavailable, the value 0xFFFF SHOULD be If the measurement is unavailable, the value 0xFFFF MUST be
reported. reported.
If the PDV Type indicated is 2-point PDV and the Positive and If the PDV Type indicated is 2-point PDV and the Positive and
Negative PDV Percentiles are set to 100.0 then the Positive and Negative PDV Percentiles are set to 100.0 then the Positive and
Negative Threshold/Peak PDV values are the peak values measured Negative Threshold/Peak PDV values are the peak values measured
during the reporting interval (which may be from the start of the during the reporting interval (which may be from the start of the
call for cumulative reports). In this case, the difference call for cumulative reports). In this case, the difference
between the Positive and Negative Threshold/Peak values defines between the Positive and Negative Threshold/Peak values defines
the range of 2-point PDV. the range of 2-point PDV.
Mean PDV: 16 bits Mean PDV: 16 bits
The mean PDV value of data packets is expressed in milliseconds The mean PDV value of data packets is expressed in milliseconds
with Numeric format S11:4 format. with Numeric format S11:4 format.
For MAPDV2 this value is generated according to Clause 6.2.3.2 of For MAPDV2 this value is generated according to Clause 6.2.3.2 of
[G.1020]. For interval reports the MAPDV2 value is reset at the [G.1020]. For interval reports the MAPDV2 value is reset at the
start of the interval. start of the interval.
For interarrival jitter, the value reported is the value of J(i)
calculated according to [RFC3550] at the time the report is
generated.
For 2-point PDV, the value reported is the mean of per-packet For 2-point PDV, the value reported is the mean of per-packet
2-point PDV values. This metric indicates the arrival time of the 2-point PDV values. This metric indicates the arrival time of the
first media packet of the session with respect to the mean of the first media packet of the session with respect to the mean of the
arrival times of every packet of the session. A single value of arrival times of every packet of the session. A single value of
the metric (for a single session) may not be useful by itself, but the metric (for a single session) may not be useful by itself, but
its average over a number of sessions may be useful in diagnosing its average over a number of sessions may be useful in diagnosing
media delay at session startup. For example, this might occur if media delay at session startup. For example, this might occur if
media packets are often delayed behind signalling packets due to media packets are often delayed behind signalling packets due to
head-of-line blocking. head-of-line blocking.
If the measured value is more negative than -2047.9375 (the value If the measured value is more negative than -2047.9375 (the value
which would be coded as 0x8001), the value 0x8000 SHOULD be which would be coded as 0x8001), the value 0x8000 SHOULD be
reported to indicate an over-range negative measurement. If the reported to indicate an over-range negative measurement. If the
measured value is more positive than +2047.8125 (the value which measured value is more positive than +2047.8125 (the value which
would be coded as 0x7FFD), the value 0x7FFE SHOULD be reported to would be coded as 0x7FFD), the value 0x7FFE SHOULD be reported to
indicate an over-range positive measurement. If the measurement indicate an over-range positive measurement. If the measurement
is unavailable, the value 0x7FFF SHOULD be reported. is unavailable, the value 0x7FFF MUST be reported.
Unused: 16 bits Reserved: 16 bits
These bits are unused. They SHOULD be set to zero by the sender These bits are reserved for future definition. They SHOULD be set
and MUST be ignored by the receiver. to zero by the sender and MUST be ignored by the receiver.
3.3. Guidance on use of PDV metrics 3.3. Guidance on use of PDV metrics
This subsection provides informative guidance on when it might be This subsection provides informative guidance on when it might be
appropriate to use each of the PDV metric types. appropriate to use each of the PDV metric types.
Interarrival jitter (Section 6.4.1 of [RFC3550]) allows comparison of MAPDV2 (Clause 6.2.3.2 of [G.1020]) is the envelope of instantaneous
results with those from RTP end systems which support only RTCP as (per-packet) delay when compared to the short term moving average
defined in [RFC3550]. delay. This metric could be useful in determining residual
impairment when an RTP end system uses an adaptive de-jitter buffer
MAPDV2 (Clause 6.2.3.2 of [G.1020]) compares instantaneous (per- which tracks the average delay variation, provided the adaptive de-
packet) delay variation against a moving average delay variation. jitter buffer have similar averaging behaviour as the MAPDV2
This metric could be useful in determining residual impairment when algorithm.
an RTP end system uses an adaptive de-jitter buffer which tracks the
average delay variation, provided the adaptive de-jitter buffer have
similar averaging behaviour as the MAPDV2 algorithm.
2-point PDV (Clause 6.2.4 of [Y.1540]) reports absolute packet delay 2-point PDV (Clause 6.2.4 of [Y.1540]) reports absolute packet delay
variation with respect to the time of arrival of the first packet of variation with respect to a defined reference packet transfer delay .
the connection. In an RTP context, the two "points" are at the Note that the reference packet is generally selected as the packet
sender (the synchronization source which applies RTP timestamps) and with minimum delay based on the most common criterion (See section 1
at the receiver. The value of this metric for the packet with index and section 5.1 of [RFC5481] ). In an RTP context, the two "points"
j is identical to the quantity D(i,j) defined in Section 6.4.1 of are at the sender (the synchronization source which applies RTP
[RFC3550] if the packet index i is set equal to 1, that is, the timestamps) and at the receiver. The value of this metric for the
reference packet for the metric is the first packet of the packet with index j is identical to the quantity D(i,j) defined in
connection. The metric includes the effect of the frequency offsets Section 6.4.1 of [RFC3550] and the packet index i should be set equal
of clocks in both the sender and receiver end systems, so it is to the index of the reference packet for the metric in practice. The
useful mainly in network where synchronisation is distributed. As metric includes the effect of the frequency offsets of clocks in both
well as measuring packet delay variation in such networks, it may be the sender and receiver end systems, so it is useful mainly in
used to ensure that synchronisation is effective, for example where network where synchronisation is distributed. As well as measuring
the network carries ISDN data traffic over RTP [RFC4040]. The metric packet delay variation in such networks, it may be used to ensure
is likely to be useful in networks which use fixed de-jitter that synchronisation is effective, for example where the network
buffering, because it may be used to determine the length of the carries ISDN data traffic over RTP [RFC4040]. The metric is likely
required de-jitter buffer, or to determine if network performance has to be useful in networks which use fixed de-jitter buffering, because
deteriorated such that existing de-jitter buffers are too small to it may be used to determine the length of the required de-jitter
accommodate the observed delay variation. buffer, or to determine if network performance has deteriorated such
that existing de-jitter buffers are too small to accommodate the
observed delay variation.
3.4. Examples of use 3.4. Examples of use
(a) To report interarrival jitter [RFC3550]:
PDV Threshold = FFFF (Undefined); PDV Percentile = FFFF
(Undefined); PDV type = 0 (interarrival jitter)
causes interarrival jitter to be reported in the Mean PDV
field.
(b) To report MAPDV2 [G.1020]: (b) To report MAPDV2 [G.1020]:
Pos PDV Threshold = 50.0; Pos PDV Percentile = 95.3; Neg PDV Pos PDV Threshold = 50.0; Pos PDV Percentile = 95.3; Neg PDV
Threshold = 50.0 (note this implies -50ms); Neg PDV Percentile Threshold = 50.0 (note this implies -50ms); Neg PDV Percentile
= 98.4; PDV type = 1 (MAPDV2) = 98.4; PDV type = 1 (MAPDV2)
causes average MAPDV2 to be reported in the Mean PDV field. causes average MAPDV2 to be reported in the Mean PDV field.
Note that implementations may either fix the reported Note that implementations may either fix the reported
percentile and calculate the associated PDV level or may fix a percentile and calculate the associated PDV level or may fix a
threshold PDV level and calculate the associated percentile. threshold PDV level and calculate the associated percentile.
From a practical implementation perspective it is simpler to From a practical implementation perspective it is simpler to
use the second of these approaches (except of course in the use the second of these approaches (except of course in the
extreme case of a 100% percentile). extreme case of a 100% percentile).
(b) To report 2-point PDV [Y.1540]:
Pos PDV Threshold = 60 (note this implies +60ms); Pos PDV
Percentile = 96.3; Neg PDV Threshold = 0; Neg PDV Percentile =
0; PDV type = 1 (2-point PDV)
causes 2-point PDV to be reported in the Mean PDV field.
2-point PDV, according to [Y.1540] is the difference in delay 2-point PDV, according to [Y.1540] is the difference in delay
between the current packet and the first packet of the stream. between the current packet and the referenced packet of the
If the sending and receiving clocks are not synchronized, this stream. If the sending and receiving clocks are not
metric includes the effect of relative timing drift. synchronized, this metric includes the effect of relative
timing drift.
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.
rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF
(defined in [RFC3611]) (defined in [RFC3611])
xr-format =/ xr-pdv-block xr-format =/ xr-pdv-block
xr-pdv-block = "pkt-dly-var" [ "," pdvtype ] [ "," nspec "," pspec ] xr-pdv-block = "pkt-dly-var" [ "," pdvtype ] [ "," nspec "," pspec ]
pdvtype = "pdv=" 0 ; interarrival jitter RFC 3550 pdvtype = "pdv=" 0 ; MAPDV2 ITU-T G.1020
/ 1 ; MAPDV2 ITU-T G.1020 / 1 ; 2-point PDV ITU-T Y.1540
/ 2 ; 2-point PDV ITU-T Y.1540
nspec = "nthr=" fixpoint ; negative PDV threshold (ms) nspec = "nthr=" fixpoint ; negative PDV threshold (ms)
/ "npc=" fixpoint ; negative PDV percentile / "npc=" fixpoint ; negative PDV percentile
pspec = "pthr=" fixpoint ; positive PDV threshold (ms) pspec = "pthr=" fixpoint ; positive PDV threshold (ms)
/ "ppc=" fixpoint ; positive PDV percentile / "ppc=" fixpoint ; positive PDV percentile
fixpoint = 1*DIGIT "." 1*DIGIT ; fixed point decimal fixpoint = 1*DIGIT "." 1*DIGIT ; fixed point decimal
DIGIT = %x30-39 DIGIT = %x30-39
When SDP is used in offer-answer, a system sending SDP may request a When SDP is used in offer-answer, a system sending SDP may request a
specific type of PDV measurement. In addition, they may state a specific type of PDV measurement. In addition, they may state a
specific percentile or threshold value, and expect to receive the specific percentile or threshold value, and expect to receive the
corresponding threshold or percentile metric, respectively. The corresponding threshold or percentile metric, respectively. The
system receiving the SDP SHOULD send the PDV metrics requested, but system receiving the SDP SHOULD send the PDV metrics requested, but
if the metric is not available, the system receiving the SDP SHOULD if the metric is not available, the system receiving the SDP MUST
send the metric block with the flag value indicating that the metric send the metric block with the flag value indicating that the metric
is unavailable. is unavailable.
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
skipping to change at page 13, line 14 skipping to change at page 13, line 14
o The review process for the registry is "Specification Required" as o The review process for the registry is "Specification Required" as
described in Section 4.1 of [RFC5226]. described in Section 4.1 of [RFC5226].
o Entries in the registry are integers. The valid range is 0 to 15 o Entries in the registry are integers. The valid range is 0 to 15
corresponding to the 4-bit field "pdvtyp" in the block. Values corresponding to the 4-bit field "pdvtyp" in the block. Values
are to be recorded in decimal. are to be recorded in decimal.
o Initial assignments are as follows: o Initial assignments are as follows:
1. interarrival jitter, Section 6.4.1 of [RFC3550], * 0: MAPDV2, Clause 6.2.3.2 of [G.1020],
2. MAPDV2, Clause 6.2.3.2 of [G.1020],
3. 2-point PDV, Clause 6.2.4 of [Y.1540] * 1: 2-point PDV, Clause 6.2.4 of [Y.1540]
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. References 7. References
skipping to change at page 15, line 40 skipping to change at page 15, line 40
BCP 26 BCP 26
[Y.1540] ITU-T, "ITU-T Rec. Y.1540, IP packet transfer and [Y.1540] ITU-T, "ITU-T Rec. Y.1540, IP packet transfer and
availability performance parameters", November 2007. availability performance parameters", November 2007.
7.2. Informative References 7.2. Informative References
[MEASI] Hunt, G., "Measurement Identity and information Reporting [MEASI] Hunt, G., "Measurement Identity and information Reporting
using SDES item and XR Block", using SDES item and XR Block",
ID draft-ietf-xrblock-rtcp-xr-measu-identity-01, ID draft-ietf-xrblock-rtcp-xr-meas-identity-06,
October 2011. April 2012.
[MONARCH] Hunt, G., "Monitoring Architectures for RTP", [MONARCH] Hunt, G., "Monitoring Architectures for RTP",
ID draft-ietf-avtcore-monarch-04, August 2011. ID draft-ietf-avtcore-monarch-13, May 2012.
[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation
Applicability Statement", RFC 5481, March 2009.
[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.
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-avt-rtcp-xr-pdv-03 A.1. draft-ietf-xrblock-rtcp-xr-pdv-03
The following are the major changes to previous version : The following are the major changes to previous version
draft-ietf-xrblock-rtcp-xr-pdv-02:
o Changed BNF for SDP following Christian Groves' and Tom Taylor's o Make definition of pdvtype get alignment with IANA section.
comments (4th and 5th May 2009).
o Updated references. o Make Guidance on use of PDV metrics get alignment with RFC5481.
A.2. draft-ietf-xrblock-rtcp-xr-pdv-00 o Other Editorial changes.
A.2. draft-ietf-xrblock-rtcp-xr-pdv-02
The following are the major changes to previous version The following are the major changes to previous version
draft-ietf-avt-rtcp-xr-pdv-03 : draft-ietf-xrblock-rtcp-xr-pdv-01:
o Updated references. o Updated references.
o Allocate one more bit for Interval metric flag to indicate sampled
metric can be used.
o Add a few clarification text for failure mode.
A.3. draft-ietf-xrblock-rtcp-xr-pdv-01 A.3. draft-ietf-xrblock-rtcp-xr-pdv-01
The following are the major changes to previous version The following are the major changes to previous version
draft-ietf-xrblock-rtcp-xr-pdv-00 : draft-ietf-xrblock-rtcp-xr-pdv-00:
o Fix typos or nits in the definition of Negative PDV Threshold/ o Fix typos or nits in the definition of Negative PDV Threshold/
Peak. Peak.
o Fix nits in Numeric format S7:8. o Fix nits in Numeric format S7:8.
o remove the text that is relevant to tag field. o remove the text that is relevant to tag field.
o Add text in SDP signaling section to clarify indicationof metric o Add text in SDP signaling section to clarify indicationof metric
unavailable. unavailable.
A.4. draft-ietf-xrblock-rtcp-xr-pdv-02 A.4. draft-ietf-xrblock-rtcp-xr-pdv-00
The following are the major changes to previous version The following are the major changes to previous version
draft-ietf-xrblock-rtcp-xr-pdv-00 : draft-ietf-avt-rtcp-xr-pdv-03:
o Updated references. o Updated references.
o Allocate one more bit for Interval metric flag to indicate sampled A.5. draft-ietf-avt-rtcp-xr-pdv-03
metric can be used.
o Add a few clarification text for failure mode. The following are the major changes to previous version :
o Changed BNF for SDP following Christian Groves' and Tom Taylor's
comments (4th and 5th May 2009).
o Updated references.
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
 End of changes. 54 change blocks. 
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