draft-ietf-xrblock-rtcp-xr-synchronization-02.txt   draft-ietf-xrblock-rtcp-xr-synchronization-03.txt 
Network Working Group H. Asaeda Network Working Group H. Asaeda
Internet-Draft NICT Internet-Draft NICT
Intended status: Standards Track R. Huang Intended status: Standards Track R. Huang
Expires: August 5, 2013 Q. Wu Expires: October 3, 2013 Q. Wu
Huawei Huawei
February 1, 2013 April 1, 2013
RTP Control Protocol (RTCP) Extended Report (XR) Blocks for RTP Control Protocol (RTCP) Extended Report (XR) Blocks for
Synchronization Delay and Offset Metrics Reporting Synchronization Delay and Offset Metrics Reporting
draft-ietf-xrblock-rtcp-xr-synchronization-02 draft-ietf-xrblock-rtcp-xr-synchronization-03
Abstract Abstract
This document defines two RTP Control Protocol (RTCP) Extended Report This document defines two RTP Control Protocol (RTCP) Extended Report
(XR) Blocks that allow the reporting of synchronization delay and (XR) Blocks that allow the reporting of synchronization delay and
offset metrics for use in a range of RTP applications. offset metrics for use in a range of RTP applications.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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 August 5, 2013. This Internet-Draft will expire on October 3, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 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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1.1. Synchronization Delay and Offset Metrics Reporting 1.1. Synchronization Delay and Offset Metrics Reporting
Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . 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. RTP Flows Initial Synchronization Delay Report Block . . . . . 5 3. RTP Flows Initial Synchronization Delay Report Block . . . . . 5
3.1. Metric Block Structure . . . . . . . . . . . . . . . . . . 5 3.1. Metric Block Structure . . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in RTP Flow Initial 3.2. Definition of Fields in RTP Flow Initial
Synchronization Delay Metrics Block . . . . . . . . . . . 5 Synchronization Delay Metrics Block . . . . . . . . . . . 6
4. RTP Flows Synchronization Offset Metrics Block . . . . . . . . 6 4. RTP Flows Synchronization Offset Metrics Block . . . . . . . . 7
4.1. Metric Block Structure . . . . . . . . . . . . . . . . . . 7 4.1. Metric Block Structure . . . . . . . . . . . . . . . . . . 7
4.2. Definition of Fields in RTP Flow General 4.2. Definition of Fields in RTP Flow General
Synchronization Offset Metrics Block . . . . . . . . . . . 7 Synchronization Offset Metrics Block . . . . . . . . . . . 8
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 8 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 9
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 9 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . . 11 9.2. Informative References . . . . . . . . . . . . . . . . . . 12
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 11 Appendix A. Metrics represented using RFC6390 Template . . . . . 12
A.1. draft-ietf-xrblock-rtcp-xr-syncronization-02 . . . . . . . 11 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 B.1. draft-ietf-xrblock-rtcp-xr-syncronization-03 . . . . . . . 13
B.2. draft-ietf-xrblock-rtcp-xr-syncronization-02 . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
1.1. Synchronization Delay and Offset Metrics Reporting Blocks 1.1. Synchronization Delay and Offset Metrics Reporting Blocks
This draft defines two new block types to augment those defined in This draft defines two new block types to augment those defined in
[RFC3611], for use in a range of RTP applications. [RFC3611], for use in a range of RTP applications.
The first new block type supports reporting of Initial The first new block type supports reporting of Initial
Synchronization Delay to establish multimedia session. Information Synchronization Delay to establish multimedia session. Information
is recorded about time difference between the start of RTP sessions is recorded about time difference between the start of RTP sessions
and the time the RTP receiver acquires all components of RTP sessions and the time the RTP receiver acquires all components of RTP sessions
in the multimedia session [RFC6051]. in the multimedia session [RFC6051].
The second new block type supports reporting of the relative The second new block type supports reporting of the relative
synchronization offset time of two arbitrary streams (e.g., between synchronization offset time of two arbitrary streams (e.g., between
audio and video streams), with the same RTCP CNAME included in RTCP audio and video streams), with the same RTCP CNAME included in RTCP
SDES packets [RFC3550]. Information is recorded about the SDES packets [RFC3550].
synchronization offset time of each RTP stream relative to the
reference RTP stream with the same CNAME and General Synchronization
Offset of zero.
These metrics belong to the class of transport level metrics defined These metrics belong to the class of transport level metrics defined
in [RFC6792]. in [RFC6792].
1.2. RTCP and RTCP XR Reports 1.2. RTCP and RTCP XR Reports
The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] The use of RTCP for reporting is defined in [RFC3550]. [RFC3611]
defined an extensible structure for reporting using an RTCP Extended defined an extensible structure for reporting using an RTCP Extended
Report (XR). This document defines a new Extended Report block for Report (XR). This document defines a new Extended Report block for
use with [RFC3550] and [RFC3611]. use with [RFC3550] and [RFC3611].
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Agreement or thresholds of the system) to help ensure the quality of Agreement or thresholds of the system) to help ensure the quality of
real-time application performance. real-time application performance.
In an RTP multimedia session, there can be an arbitrary number of In an RTP multimedia session, there can be an arbitrary number of
streams carried in different RTP sessions, with the same RTCP CNAME. streams carried in different RTP sessions, with the same RTCP CNAME.
These streams may be not synchronized with each other. For example, These streams may be not synchronized with each other. For example,
one audio stream and one video stream belong to the same session, and one audio stream and one video stream belong to the same session, and
the audio stream is transmitted lagging behind video stream for the audio stream is transmitted lagging behind video stream for
multiple tens of milliseconds [TR-126]. The RTP Flows multiple tens of milliseconds [TR-126]. The RTP Flows
Synchronization Offset block can be used to report such Synchronization Offset block can be used to report such
synchronization offset between video stream and audio stream. The synchronization offset between video stream and audio stream. This
metrics defined in the RTP flows synchronization Offset block can be block is also applied to the case where an RTP session can contain
used by network manager for trouble shooting and dealing with user media streams with media from multiple media types. The metrics
experience issues. defined in the RTP flows synchronization Offset block can be used by
network manager for trouble shooting and dealing with user experience
issues.
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:
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A multimedia session comprises a set of concurrent RTP sessions A multimedia session comprises a set of concurrent RTP sessions
among a common group of participants, using one RTP session for among a common group of participants, using one RTP session for
each media type. The initial synchronization Delay is the average each media type. The initial synchronization Delay is the average
time for receiver to synchronize all components of a multimedia time for receiver to synchronize all components of a multimedia
session [RFC6051]. session [RFC6051].
Synchronization Offset: Synchronization Offset:
Synchronization between two media streams must be maintained to Synchronization between two media streams must be maintained to
ensure satisfactory QoE. Two media streams can be of the same ensure satisfactory QoE. Two media streams can be of the same or
media type belonging to one RTP session or in different media different media type belonging to one RTP session or in different
types belonging to one multimedia session. The Synchronization media types belonging to one multimedia session. The
Offset is the relative time difference of the two media streams Synchronization Offset is the relative time difference of the two
that need to be synchronized. media streams that need to be synchronized.
3. RTP Flows Initial Synchronization Delay Report Block 3. RTP Flows Initial Synchronization Delay Report Block
This block is sent by RTP receivers and reports Initial This block is sent by RTP receivers and reports Initial
synchronization delay beyond the information carried in the standard synchronization delay beyond the information carried in the standard
RTCP packet format. Information is recorded about time difference RTCP packet format. Information is recorded about time difference
between the start of multimedia session and the time when the RTP between the start of multimedia session and the time when the RTP
receiver acquires all components of RTP sessions [RFC6051]. receiver acquires all components of RTP sessions [RFC6051] measured
at the receiving end of RTP stream.
Instances of this Block refer by Synchronization source (SSRC) to the
separate auxiliary Measurement Information block [RFC6776] which
describes measurement periods in use (see [RFC6776] section 4.2).
This metrics block relies on the measurement period in the
Measurement Information block indicating the span of the report and
SHOULD be sent in the same compound RTCP packet as the measurement
information block. If the measurement period is not received in the
same compound RTCP packet as this Block, this Block MUST be
discarded.
3.1. Metric Block Structure 3.1. Metric Block Structure
The RTP Flows Initial Synchronization Delay Report Block has the The RTP Flows Initial Synchronization Delay Report Block has the
following format: following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=RFISD | Reserved | Block length=2 | | BT=RFISD | I | Reserved | Block length=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source | | SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Initial Synchronization Delay | | Initial Synchronization Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2. Definition of Fields in RTP Flow Initial Synchronization Delay 3.2. Definition of Fields in RTP Flow Initial Synchronization Delay
Metrics Block Metrics Block
Block type (BT): 8 bits Block type (BT): 8 bits
The RTP Flows Initial Synchronization Delay Report Block is The RTP Flows Initial Synchronization Delay Report Block is
identified by the constant <RFISD>. identified by the constant <RFISD>.
Reserved: 8 bits Interval Metric Flag (I): 2 bits
This field is used to indicate whether the Burst/Gap Discard
Summary Statistics metrics are Sampled, Interval or Cumulative
metrics:
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 value I=00 is the reserved value and MUST
NOT be used.
Reserved: 6 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 MUST be set to zero and
MUST be ignored by the receiver. MUST be ignored by the receiver.
Block length: 16 bits Block length: 16 bits
The constant 2, in accordance with the definition of this field in The constant 2, in accordance with the definition of this field in
Section 3 of RFC 3611 [RFC3611]. Section 3 of RFC 3611 [RFC3611].
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taken to receive the first RTCP packet in the RTP session with the taken to receive the first RTCP packet in the RTP session with the
longest RTCP reporting interval or the average time taken to longest RTCP reporting interval or the average time taken to
receive the first RTP header extension containing in-band mapping receive the first RTP header extension containing in-band mapping
of RTP and NTP- format timestamps. of RTP and NTP- format timestamps.
If the measurement is unavailable, the value of this field with If the measurement is unavailable, the value of this field with
all bits set to 1 MUST be reported. all bits set to 1 MUST be reported.
4. RTP Flows Synchronization Offset Metrics Block 4. RTP Flows Synchronization Offset Metrics Block
In the RTP multimedia sessions, there can be an arbitrary number of In the RTP multimedia sessions or one RTP session, there can be an
Media streams and each media stream (e.g., audio stream or video arbitrary number of Media streams and each media stream (e.g., audio
stream) is sent in a separate RTP stream. The receiver associates stream or video stream) is sent in a separate RTP stream. In case of
RTP streams to be synchronized by means of RTCP CNAME contained in one RTP session, each media stream or each medium uses different
the RTCP Source Description (SDES) packets [RFC3550]. SSRC. The receiver associates RTP streams to be synchronized by
means of RTCP CNAME contained in the RTCP Source Description (SDES)
packets [RFC3550].
This block is sent by RTP receivers and reports synchronization This block is sent by RTP receivers and reports synchronization
offset of the arbitrary two RTP streams that needs to be synchronized offset of two arbitrary RTP streams that needs to be synchronized in
in the RTP multimedia session. Information is recorded about the the RTP multimedia session. Information is recorded about the
relative average time difference between the reporting stream and the relative average time difference between two arbitrary RTP streams
reference stream with the same CNAME. For multimedia session with with the same CNAME and measured at the receiving end of RTP stream.
multiple media types (e.g., audio and video), it is recommended to
choose the stream with the lower bandwidth as the reference stream. Instances of this Block refer by Synchronization source (SSRC) to the
For layered video sessions, it is recommended to use the base layer separate auxiliary Measurement Information block [RFC6776] which
stream as the reference stream. describes measurement periods in use (see [RFC6776] section 4.2).
This metrics block relies on the measurement period in the
Measurement Information block indicating the span of the report and
SHOULD be sent in the same compound RTCP packet as the measurement
information block. If the measurement period is not received in the
same compound RTCP packet as this Block, this Block MUST be
discarded.
4.1. Metric Block Structure 4.1. Metric Block Structure
The RTP Flow General Synchronization Offset Report Block has the The RTP Flow General Synchronization Offset Report Block has the
following format: following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=RFSO | Reserved | Block length=4 | | BT=RFSO | I | Reserved | Block length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source | | SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of reference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Synchronization Offset, most significant word | | Synchronization Offset, most significant word |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Synchronization Offset, least significant word | | Synchronization Offset, least significant word |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.2. Definition of Fields in RTP Flow General Synchronization Offset 4.2. Definition of Fields in RTP Flow General Synchronization Offset
Metrics Block Metrics Block
Block type (BT): 8 bits Block type (BT): 8 bits
The RTP Flow General Synchronization Offset Report Block is The RTP Flow General Synchronization Offset Report Block is
identified by the constant <RFSO>. identified by the constant <RFSO>.
Reserved: 8 bits Interval Metric Flag (I): 2 bits
This field is used to indicate whether the Burst/Gap Discard
Summary Statistics metrics are Sampled, Interval or Cumulative
metrics:
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 value I=00 is the reserved value and MUST
NOT be used.
Reserved: 6 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 MUST be set to zero and
MUST be ignored by the receiver. MUST be ignored by the receiver.
Block length: 16 bits Block length: 16 bits
The constant 4, in accordance with the definition of this field in The constant 3, in accordance with the definition of this field in
Section 3 of RFC 3611 [RFC3611]. Section 3 of RFC 3611 [RFC3611].
SSRC of Source: 32 bits SSRC of Source: 32 bits
The SSRC of the media source SHALL be set to the value of the SSRC The SSRC of the media source SHALL be set to the value of the SSRC
identifier of the reporting RTP stream to which the XR relates. identifier of the reporting RTP stream to which the XR relates.
SSRC of Reference: 32 bits
The SSRC of the reference stream SHALL be set to the value of the
SSRC identifier of the reference RTP stream to which the XR
relates.
Synchronization Offset: 64 bits Synchronization Offset: 64 bits
The synchronization offset of the reporting RTP stream relative to The synchronization offset of two arbitrary RTP streams with the
the reference RTP stream with the same CNAME. The calculation of common CNAME. The calculation of Synchronization Offset is
Synchronization Offset is similar to Difference D calculation in similar to Difference D calculation in the RFC3550. That is to
the RFC3550. That is to say, if Si is the NTP timestamp from the say, if Si is the NTP timestamp from the reporting RTP packet i,
reporting RTP packet i, and Ri is the time of arrival in NTP and Ri is the time of arrival in NTP timestamp units for reporting
timestamp units for reporting RTP packet i, Sj is the NTP RTP packet i, Sj is the NTP timestamp from the reference RTP
timestamp from the reference RTP packet j, and Rj is the time of packet j, and Rj is the time of arrival in NTP timestamp units for
arrival in NTP timestamp units for reference RTP packet j, then reference RTP packet j, then the value of the synchronization
the value of the synchronization offset D may be expressed as offset D may be expressed as
D(i,j) = (Rj - Ri) - (Sj - Si) = (Rj - Sj) - (Ri - Si) D(i,j) = (Rj - Ri) - (Sj - Si) = (Rj - Sj) - (Ri - Si)
If in-band delivery of NTP-format timestamps is supported If in-band delivery of NTP-format timestamps is supported
[RFC6051], Si and Sj should be obtained directly from the RTP [RFC6051], Si and Sj should be obtained directly from the RTP
packets where NTP timestamps are available. If not, Si and Sj packets where NTP timestamps are available. If not, Si and Sj
should be calculated from their corresponding RTP timestamps. The should be calculated from their corresponding RTP timestamps. The
value of the synchronization offset is represented using a 64- bit value of the synchronization offset is represented using a 64-bit
signed NTP-format timestamp as defined in [RFC5905], which is 64- unsigned NTP-format timestamp as defined in [RFC5905], which is
bit signed fixed-point number with the integer part in the first 64-bit unsigned fixed-point number with the integer part in the
32 bits and the fractional part in the last 32 bits. A positive first 32 bits and the fractional part in the last 32 bits.
value of the synchronization offset means that the reporting
stream leads before the reference stream, while a negative value
means that the reporting stream lags behind the reference stream.
If the measurement is unavailable, the value of this field with If the measurement is unavailable, the value of this field with
all bits set to 1 MUST be reported. all bits set to 1 MUST be reported.
5. SDP Signaling 5. 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.
5.1. SDP rtcp-xr-attrib Attribute Extension 5.1. SDP rtcp-xr-attrib Attribute Extension
Two new parameters are defined for the two report blocks defined in Two new parameters are defined for the two report blocks defined in
this document to be used with Session Description Protocol (SDP) this document to be used with Session Description Protocol (SDP)
[RFC4566] using the Augmented Backus-Naur Form (ABNF) [RFC5234]. [RFC4566] using the Augmented Backus-Naur Form (ABNF) [RFC5234].
They have the following syntax within the "rtcp-xr" attribute
They have the following syntax within the "rtcp-xr" attribute
[RFC3611]: [RFC3611]:
xr-format = xr-rfisd-block xr-format = xr-rfisd-block
/ xr-rfso-block / xr-rfso-block
xr-rfisd-block = " init-syn-delay" xr-rfisd-block = " init-syn-delay"
xr-rfso-block = " syn-offset" xr-rfso-block = " syn-offset"
Refer to Section 5.1 of RFC 3611 [RFC3611] for a detailed description Refer to Section 5.1 of RFC 3611 [RFC3611] for a detailed description
and the full syntax of the "rtcp-xr" attribute. and the full syntax of the "rtcp-xr" attribute.
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7. Security Considerations 7. Security Considerations
The new RTCP XR report blocks proposed in this document introduces no The new RTCP XR report blocks proposed in this document introduces no
new security considerations beyond those described in [RFC3611]. new security considerations beyond those described in [RFC3611].
8. Acknowledgements 8. Acknowledgements
The authors would like to thank Bill Ver Steeg, David R Oran, Ali The authors would like to thank Bill Ver Steeg, David R Oran, Ali
Begen, Colin Perkins, Roni Even, Kevin Gross, Jing Zhao, Fernando Begen, Colin Perkins, Roni Even, Kevin Gross, Jing Zhao, Fernando
Boronat Segui, Mario Montagud Climent, Youqing Yang, Wenxiao Yu and Boronat Segui, Mario Montagud Climent, Youqing Yang, Wenxiao Yu and
Yinliang Hu for their valuable comments and suggestions on this Yinliang Hu,Jonathan Lennox for their valuable comments and
document. suggestions on this document.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
skipping to change at page 11, line 9 skipping to change at page 12, line 9
Time Protocol Version 4: Protocol and Algorithms Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010. Specification", RFC 5905, June 2010.
[RFC6051] Perkins, C. and T. Schierl, "Rapid Synchronisation of RTP [RFC6051] Perkins, C. and T. Schierl, "Rapid Synchronisation of RTP
Flows", RFC 6051, November 2010. Flows", RFC 6051, November 2010.
[RFC6190] Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis, [RFC6190] Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis,
"RTP Payload Format for Scalable Video Coding", RFC 6190, "RTP Payload Format for Scalable Video Coding", RFC 6190,
May 2011. May 2011.
[TR-126] BBF Forum, "Triple-play Services Quality of Experience [RFC6776] Wu, Q., "Measurement Identity and information Reporting
(QoE) Requirements", December 2006. using SDES item and XR Block", RFC 6776, August 2012.
9.2. Informative References 9.2. Informative References
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New
Performance Metric Development", RFC 6390, October 2011.
[RFC6792] Wu, Q., "Guidelines for Use of the RTP Monitoring [RFC6792] Wu, Q., "Guidelines for Use of the RTP Monitoring
Framework", RFC 6792, November 2012. Framework", RFC 6792, November 2012.
[TR-126] BBF Forum, "Triple-play Services Quality of Experience
(QoE) Requirements", December 2006.
[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.
Appendix A. Change Log Appendix A. Metrics represented using RFC6390 Template
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC
number, when assigned.
a. Initial Synchronization Delay Metric
* Metric Name: RTP Initial Synchronization Delay
* Metric Description: See Section 2.1,Initial Synchronization
Delay term [RFCXXXX].
* Method of Measurement or Calculation: See section 3.2, Initial
Synchronization Delay definition [RFCXXXX].
* Units of Measurement: See section 3.2, Initial Synchronization
Delay definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 3, 1st paragraph [RFCXXXX].
* Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for
measurement timing and section 3.2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
b. Synchronization Offset Metric
* Metric Name: RTP Synchronization Offset Delay
* Metric Description: See Section 2.1, Synchronization Offset
term [RFCXXXX].
* Method of Measurement or Calculation: See section 4.2, Initial
Synchronization Delay definition definition [RFCXXXX].
* Units of Measurement: See section 4.2, Initial Synchronization
Delay definition definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See
section 4, 2nd paragraph [RFCXXXX].
* Measurement Timing: See section 4, 3rd paragraph [RFCXXXX] for
measurement timing and section 4.2 [RFCXXXX] for Interval
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611.
Appendix B. Change Log
Note to the RFC-Editor: please remove this section prior to Note to the RFC-Editor: please remove this section prior to
publication as an RFC. publication as an RFC.
A.1. draft-ietf-xrblock-rtcp-xr-syncronization-02 B.1. draft-ietf-xrblock-rtcp-xr-syncronization-03
The following are the major changes compared to previous version:
Remove the need to signal the reference source in the
synchronisation offset metrics RTCP XR report.
Apply RFC6390 template to metrics in the appendix.
Other editorial changes to get inline with other XRBLOCK drafts.
B.2. draft-ietf-xrblock-rtcp-xr-syncronization-02
The following are the major changes compared to previous version: The following are the major changes compared to previous version:
Editorial change based on comments raised on the list and in the Editorial change based on comments raised on the list and in the
IETF85 meeting IETF85 meeting
Authors' Addresses Authors' Addresses
Hitoshi Asaeda Hitoshi Asaeda
National Institute of Information and Communications Technology National Institute of Information and Communications Technology
 End of changes. 29 change blocks. 
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