draft-ietf-xrblock-rtcp-xr-synchronization-03.txt   draft-ietf-xrblock-rtcp-xr-synchronization-04.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: October 3, 2013 Q. Wu Expires: October 5, 2013 Q. Wu
Huawei Huawei
April 1, 2013 April 3, 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-03 draft-ietf-xrblock-rtcp-xr-synchronization-04
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
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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 October 3, 2013. This Internet-Draft will expire on October 5, 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 . . . . . . . . . . . 6 Synchronization Delay Metrics Block . . . . . . . . . . . 5
4. RTP Flows Synchronization Offset Metrics Block . . . . . . . . 7 4. RTP Flows Synchronization Offset Metrics Block . . . . . . . . 6
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 . . . . . . . . . . . 8 Synchronization Offset Metrics Block . . . . . . . . . . . 7
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 9 5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . . 9
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 10 5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
9.1. Normative References . . . . . . . . . . . . . . . . . . . 11 9.1. Normative References . . . . . . . . . . . . . . . . . . . 11
9.2. Informative References . . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . . 11
Appendix A. Metrics represented using RFC6390 Template . . . . . 12 Appendix A. Metrics represented using RFC6390 Template . . . . . 12
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 13 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 13
B.1. draft-ietf-xrblock-rtcp-xr-syncronization-03 . . . . . . . 13 B.1. draft-ietf-xrblock-rtcp-xr-syncronization-04 . . . . . . . 13
B.2. draft-ietf-xrblock-rtcp-xr-syncronization-02 . . . . . . . 13 B.2. draft-ietf-xrblock-rtcp-xr-syncronization-03 . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 B.3. draft-ietf-xrblock-rtcp-xr-syncronization-02 . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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
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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] measured receiver acquires all components of RTP sessions [RFC6051] measured
at the receiving end of RTP stream. at the receiving end of RTP stream.
Instances of this Block refer by Synchronization source (SSRC) to the This block needs only be exchanged occasionally, for example sent
separate auxiliary Measurement Information block [RFC6776] which once at the start of RTP session.
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 | I | Reserved | Block length=2 | | BT=RFISD | 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>.
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 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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stream or video stream) is sent in a separate RTP stream. In case of stream or video stream) is sent in a separate RTP stream. In case of
one RTP session, each media stream or each medium uses different one RTP session, each media stream or each medium uses different
SSRC. The receiver associates RTP streams to be synchronized by SSRC. The receiver associates RTP streams to be synchronized by
means of RTCP CNAME contained in the RTCP Source Description (SDES) means of RTCP CNAME contained in the RTCP Source Description (SDES)
packets [RFC3550]. packets [RFC3550].
This block is sent by RTP receivers and reports synchronization This block is sent by RTP receivers and reports synchronization
offset of two arbitrary RTP streams that needs to be synchronized in offset of two arbitrary RTP streams that needs to be synchronized in
the RTP multimedia session. Information is recorded about the the RTP multimedia session. Information is recorded about the
relative average time difference between two arbitrary RTP streams relative average time difference between two arbitrary RTP streams
with the same CNAME and measured at the receiving end of RTP stream. (one is reporting stream, the other is reference stream) with the
same CNAME and measured at the receiving end of RTP stream. In order
to tell what the offset of reporting stream is relative to, the block
for reference stream with synchronization offset of zero should be
reported.
Instances of this Block refer by Synchronization source (SSRC) to the Instances of this Block refer by Synchronization source (SSRC) to the
separate auxiliary Measurement Information block [RFC6776] which separate auxiliary Measurement Information block [RFC6776] which
describes measurement periods in use (see [RFC6776] section 4.2). describes measurement periods in use (see [RFC6776] section 4.2).
This metrics block relies on the measurement period in the This metrics block relies on the measurement period in the
Measurement Information block indicating the span of the report and Measurement Information block indicating the span of the report and
SHOULD be sent in the same compound RTCP packet as the measurement SHOULD be sent in the same compound RTCP packet as the measurement
information block. If the measurement period is not received in the information block. If the measurement period is not received in the
same compound RTCP packet as this Block, this Block MUST be same compound RTCP packet as this Block, this Block MUST be
discarded. discarded.
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The constant 3, 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.
Synchronization Offset: 64 bits Synchronization Offset: 64 bits
The synchronization offset of two arbitrary RTP streams with the The synchronization offset of the reporting RTP stream relative to
common CNAME. The calculation of Synchronization Offset is the reference stream with the same CNAME. The calculation of
similar to Difference D calculation in the RFC3550. That is to Synchronization Offset is similar to Difference D calculation in
say, if Si is the NTP timestamp from the reporting RTP packet i, the RFC3550. That is to say, if Si is the NTP timestamp from the
and Ri is the time of arrival in NTP timestamp units for reporting reporting RTP packet i, and Ri is the time of arrival in NTP
RTP packet i, Sj is the NTP timestamp from the reference RTP timestamp units for reporting RTP packet i, Sj is the NTP
packet j, and Rj is the time of arrival in NTP timestamp units for timestamp from the reference RTP packet j, and Rj is the time of
reference RTP packet j, then the value of the synchronization arrival in NTP timestamp units for reference RTP packet j, then
offset D may be expressed as the value of the synchronization 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
unsigned NTP-format timestamp as defined in [RFC5905], which is signed NTP-format timestamp as defined in [RFC5905], which is 64-
64-bit unsigned fixed-point number with the integer part in the bit signed fixed-point number with the integer part in the first
first 32 bits and the fractional part in the last 32 bits. 32 bits and the fractional part in the last 32 bits. . A positive
value of the synchronization offset means that the reporting
stream leads before the reference stream, while a negative one
means the reporting stream lags behind the reference stream. The
synchronization offset of zero means the stream is 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.
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* Method of Measurement or Calculation: See section 3.2, Initial * Method of Measurement or Calculation: See section 3.2, Initial
Synchronization Delay definition [RFCXXXX]. Synchronization Delay definition [RFCXXXX].
* Units of Measurement: See section 3.2, Initial Synchronization * Units of Measurement: See section 3.2, Initial Synchronization
Delay definition [RFCXXXX]. Delay definition [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 3, 1st paragraph [RFCXXXX]. section 3, 1st paragraph [RFCXXXX].
* Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for * Measurement Timing: See section 3, 2nd paragraph [RFCXXXX] for
measurement timing and section 3.2 [RFCXXXX] for Interval measurement timing.
Metric flag.
* Use and applications: See section 1.4 [RFCXXXX]. * Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611. * Reporting model: See RFC3611.
b. Synchronization Offset Metric b. Synchronization Offset Metric
* Metric Name: RTP Synchronization Offset Delay * Metric Name: RTP Synchronization Offset Delay
* Metric Description: See Section 2.1, Synchronization Offset * Metric Description: See Section 2.1, Synchronization Offset
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* Use and applications: See section 1.4 [RFCXXXX]. * Use and applications: See section 1.4 [RFCXXXX].
* Reporting model: See RFC3611. * Reporting model: See RFC3611.
Appendix B. Change Log 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.
B.1. draft-ietf-xrblock-rtcp-xr-syncronization-03 B.1. draft-ietf-xrblock-rtcp-xr-syncronization-04
The following are the major changes compared to previous version:
Additional text to clarify on how to distinguish report stream
from reference stream.
Other Editorial changes.
B.2. draft-ietf-xrblock-rtcp-xr-syncronization-03
The following are the major changes compared to previous version: The following are the major changes compared to previous version:
Remove the need to signal the reference source in the Remove the need to signal the reference source in the
synchronisation offset metrics RTCP XR report. synchronisation offset metrics RTCP XR report.
Apply RFC6390 template to metrics in the appendix. Apply RFC6390 template to metrics in the appendix.
Other editorial changes to get inline with other XRBLOCK drafts. Other editorial changes to get inline with other XRBLOCK drafts.
B.2. draft-ietf-xrblock-rtcp-xr-syncronization-02 B.3. 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. 19 change blocks. 
59 lines changed or deleted 51 lines changed or added

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