draft-ietf-avtcore-monarch-09.txt   draft-ietf-avtcore-monarch-10.txt 
Audio/Video Transport Working Group Q. Wu, Ed. Audio/Video Transport Working Group Q. Wu, Ed.
Internet-Draft Huawei Internet-Draft Huawei
Intended status: Informational G. Hunt Intended status: Informational G. Hunt
Expires: July 15, 2012 Unaffiliated Expires: August 27, 2012 Unaffiliated
P. Arden P. Arden
BT BT
January 12, 2012 February 24, 2012
Monitoring Architectures for RTP Monitoring Architecture for RTP
draft-ietf-avtcore-monarch-09.txt draft-ietf-avtcore-monarch-10.txt
Abstract Abstract
This memo proposes an architecture for extending RTCP with a new RTCP This memo proposes an architecture for extending RTP Control Protocol
XR (RFC3611) block type to report new metrics regarding media (RTCP) with a new RTCP Extended Reports (XR) (RFC3611) block type to
transmission or reception quality, following RTCP guideline report new metrics regarding media transmission or reception quality,
established in RFC5968. This memo suggests that a new block should following RTCP guideline established in RFC5968. This memo suggests
contain a single metric or a small number of metrics relevant to a that a new block should contain a single metric or a small number of
single parameter of interest or concern, rather than containing a metrics relevant to a single parameter of interest or concern, rather
number of metrics which attempt to provide full coverage of all those than containing a number of metrics which attempt to provide full
parameters of concern to a specific application. Applications may coverage of all those parameters of concern to a specific
then "mix and match" to create a set of blocks which covers their set application. Applications may then "mix and match" to create a set
of concerns. Where possible, a specific block should be designed to of blocks which covers their set of concerns. Where possible, a
be re-usable across more than one application, for example, for all specific block should be designed to be re-usable across more than
of voice, streaming audio and video. one application, for example, for all of voice, streaming audio and
video.
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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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 July 15, 2012. This Internet-Draft will expire on August 27, 2012.
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.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. RTP monitoring architecture . . . . . . . . . . . . . . . . . 6 3. RTP monitoring architecture . . . . . . . . . . . . . . . . . 6
3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. RTCP Metric Block Report and associated parameters . . . . 8 3.2. RTCP Metric Block Report and associated parameters . . . . 9
3.3. RTP Sender/Receiver entities located in network nodes . . 9 3.3. RTP Sender/Receiver entities located in network nodes . . 10
4. Issues with reporting metric block using RTCP XR extension . . 10 4. Issues with reporting metric block using RTCP XR extension . . 11
5. Guideline for reporting metric block using RTCP XR . . . . . . 12 5. Guideline for reporting metric block using RTCP XR . . . . . . 13
5.1. Using single metrics blocks . . . . . . . . . . . . . . . 12 5.1. Using single metrics blocks . . . . . . . . . . . . . . . 13
5.2. Correlating RTCP XR with the non-RTP data . . . . . . . . 12 5.2. Correlating RTCP XR with the non-RTP data . . . . . . . . 13
5.3. Reducing Measurement information repetition . . . . . . . 13 5.3. Reducing Measurement information repetition . . . . . . . 14
5.4. Expanding the RTCP XR block namespace . . . . . . . . . . 13 5.4. Expanding the RTCP XR block namespace . . . . . . . . . . 14
6. An example of a metric block . . . . . . . . . . . . . . . . . 15 6. An example of a metric block . . . . . . . . . . . . . . . . . 16
7. Application to RFC 5117 topologies . . . . . . . . . . . . . . 16 7. Application to RFC 5117 topologies . . . . . . . . . . . . . . 17
7.1. Applicability to MCU . . . . . . . . . . . . . . . . . . . 16 7.1. Applicability to MCU . . . . . . . . . . . . . . . . . . . 17
7.2. Applicability to Translators . . . . . . . . . . . . . . . 17 7.2. Applicability to Translators . . . . . . . . . . . . . . . 18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19 9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 20 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 21
11. Informative References . . . . . . . . . . . . . . . . . . . . 21 11. Informative References . . . . . . . . . . . . . . . . . . . . 22
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 23 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 24
A.1. draft-ietf-avtcore-monarch-00 . . . . . . . . . . . . . . 23 A.1. draft-ietf-avtcore-monarch-00 . . . . . . . . . . . . . . 24
A.2. draft-ietf-avtcore-monarch-01 . . . . . . . . . . . . . . 23 A.2. draft-ietf-avtcore-monarch-01 . . . . . . . . . . . . . . 24
A.3. draft-ietf-avtcore-monarch-02 . . . . . . . . . . . . . . 23 A.3. draft-ietf-avtcore-monarch-02 . . . . . . . . . . . . . . 24
A.4. draft-ietf-avtcore-monarch-03 . . . . . . . . . . . . . . 24 A.4. draft-ietf-avtcore-monarch-03 . . . . . . . . . . . . . . 25
A.5. draft-ietf-avtcore-monarch-04 . . . . . . . . . . . . . . 24 A.5. draft-ietf-avtcore-monarch-04 . . . . . . . . . . . . . . 25
A.6. draft-ietf-avtcore-monarch-05 . . . . . . . . . . . . . . 24 A.6. draft-ietf-avtcore-monarch-05 . . . . . . . . . . . . . . 25
A.7. draft-ietf-avtcore-monarch-06 . . . . . . . . . . . . . . 25 A.7. draft-ietf-avtcore-monarch-06 . . . . . . . . . . . . . . 26
A.8. draft-ietf-avtcore-monarch-07 . . . . . . . . . . . . . . 25 A.8. draft-ietf-avtcore-monarch-07 . . . . . . . . . . . . . . 26
A.9. draft-ietf-avtcore-monarch-08 . . . . . . . . . . . . . . 25 A.9. draft-ietf-avtcore-monarch-08 . . . . . . . . . . . . . . 26
A.10. draft-ietf-avtcore-monarch-09 . . . . . . . . . . . . . . 25 A.10. draft-ietf-avtcore-monarch-09 . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26 A.11. draft-ietf-avtcore-monarch-10 . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
As more users and subscribers rely on real time application services, As the delivery of multimedia services using the Real-Time Transport
Protocol (RTP) over IP network is gaining an increasing popularity,
uncertainties in the performance and availability of these services uncertainties in the performance and availability of these services
are driving the need to support new standard methods for gathering are driving the need to support new standard methods for gathering
performance metrics from RTP applications. These rapidly emerging performance metrics from RTP applications. These rapidly emerging
standards, such as RTCP XR [RFC3611] and other RTCP extension to standards, such as RTP Control Protocol Extended Reports (RTCP
Sender Reports (SR), Receiver Reports (RR) [RFC3550] are being XR)[RFC3611] and other RTCP extension to Sender Reports (SR),
developed for the purpose of collecting and reporting performance Receiver Reports (RR) [RFC3550] are being developed for the purpose
metrics from endpoint devices that can be used to correlate the of collecting and reporting performance metrics from endpoint devices
metrics, provide end to end service visibility and measure and that can be used to correlate the metrics, provide end to end service
monitor Quality of Experience (QoE). visibility and measure and monitor Quality of Experience (QoE)
[RFC6390].
However the proliferation of RTP/RTCP specific metrics for transport However the proliferation of RTP/RTCP specific metrics for transport
and application quality monitoring has been identified as a potential and application quality monitoring has been identified as a potential
problem for RTP/RTCP interoperability, which attempt to provide full problem for RTP/RTCP interoperability, which attempt to provide full
coverage of all those parameters of concern to a specific coverage of all those parameters of concern to a specific
application. Since different applications layered on RTP may have application. Given that different applications layered on RTP may
some monitoring requirements in common, therefore these metrics have some monitoring requirements in common, these metrics should be
should be satisfied by a common design. satisfied by a common design.
The objective of this document is to define an extensible RTP The objective of this document is to define an extensible RTP
monitoring framework to provide a small number of re-usable Quality monitoring framework to provide a small number of re-usable Quality
of Service (QoS)/QoE metrics which facilitate reduced implementation of Service (QoS)/QoE metrics which facilitate reduced implementation
costs and help maximize inter-operability. RTCP Guideline [RFC5968] costs and help maximize inter-operability. RTCP Guideline [RFC5968]
has stated that, where RTCP is to be extended with a new metric, the has stated that, where RTCP is to be extended with a new metric, the
preferred mechanism is by the addition of a new RTCP XR [RFC3611] preferred mechanism is by the addition of a new RTCP XR [RFC3611]
block. This memo assumes that any requirement for a new metric to be block. This memo assumes that any requirement for a new metric to be
transported in RTCP will use a new RTCP XR block. transported in RTCP will use a new RTCP XR block.
2. Requirements notation 2. Terminology
This memo is informative and as such contains no normative This memo is informative and as such contains no normative
requirements. requirements.
In addition, the following terms are defined: In addition, the following terms are defined:
Transport level metrics Transport level metrics
A set of metrics which characterise the three transport A set of metrics which characterise the three transport
impairments of packet loss, packet delay, and packet delay impairments of packet loss, packet delay, and packet delay
skipping to change at page 4, line 27 skipping to change at page 4, line 27
which uses RTP transport. which uses RTP transport.
Application level metrics Application level metrics
Metrics relating to application specific parameters or QoE related Metrics relating to application specific parameters or QoE related
parameters. Application specific parameters are measured at the parameters. Application specific parameters are measured at the
application level and focus on quality of content rather than application level and focus on quality of content rather than
network performance. QoE related parameters reflect the end-to- network performance. QoE related parameters reflect the end-to-
end performance at the services level and is ususally measured at end performance at the services level and is ususally measured at
the user endpoint. One example of such metrics is the QoE Metric the user endpoint. One example of such metrics is the QoE Metric
specified in QoE metric reporting Block [MQ]. specified in QoE metric reporting Block [QOE].
End System metrics End System metrics
Metrics relating to the way a terminal deals with transport Metrics relating to the way a terminal deals with transport
impairments affecting the incident RTP stream. These may include impairments affecting the incident RTP stream. These may include
de-jitter buffering, packet loss concealment, and the use of de-jitter buffering, packet loss concealment, and the use of
redundant streams (if any) for correction of error or loss. redundant streams (if any) for correction of error or loss.
Direct metrics Direct metrics
Metrics that can be directly measured or calculated and are not Metrics that can be directly measured or calculated and are not
dependent on other metric. dependent on other metric.
Composed metrics Composed metrics
Metrics that are calculated based on direct metric or combination Metrics that are calculated based on Direct metric that have been
of direct metric and derived metrics. measured or combination of Direct metrics that are identical to
the metric being composed.
Interval metrics Interval metrics
It is referred to as the metrics of which the reported values It is referred to as the metrics of which the reported values
apply to the most recent measurement interval duration between apply to the most recent measurement interval duration between
successive metrics reports successive metrics reports.
Cumulative metrics Cumulative metrics
It is referred to as the metrics of which the reported values It is referred to as the metrics of which the reported values
apply to the accumulation period characteristic of cumulative apply to the accumulation period characteristic of cumulative
measurements measurements.
Sampled metrics Sampled metrics
It is referred to as the metrics of which the reported values only It is referred to as the metrics of which the reported values only
apply to the value of a continuously measured or calculated that apply to the value of a continuously measured or calculated that
has been sampled at end of the interval. has been sampled at end of the interval.
3. RTP monitoring architecture 3. RTP monitoring architecture
There are many ways in which the performance of an RTP session can be
monitored. These include RTP-based mechanisms such as the RTP SNMP
MIB [RFC2959], or the SIP event package for RTCP summary reports
[RFC6035], or non-RTP mechanisms such as generic MIBs, NetFlow,
IPFix, and so on. Together, these provide useful mechanisms for
exporting data on the performance of an RTP session to non-RTP
network management systems. It is desirable to also perform in-
session monitoring of RTP performance. RTCP provides the means to do
this. In the following, we specify an architecture for using and
extending RTCP for monitoring RTP sessions. One major benefit of
such architecture is ease of integration with other RTP/RTCP
mechanism.
3.1. Overview 3.1. Overview
The RTP monitoring architecture comprises the following two key The RTP monitoring architecture comprises the following two key
functional components shown below: functional components shown below:
o Monitor o RTP Monitor
o Metric Block Structure o RTP Metric Block Structure
Monitor is the functional component defined in the Real-time RTP Monitor is the functional component defined in the Real-time
Transport Protocol (RTP) [RFC3550] that acts as a source of Transport Protocol [RFC3550] that acts as a source of information
information gathered for monitoring purposes. It may gather such gathered for monitoring purposes. It may gather such information
information reported by RTCP XR or other RTCP extension and calculate reported by RTCP XR or other RTCP extension and calculate statistics
statistics from multiple source. According to the definition of from multiple source. According to the definition of monitor in the
monitor in the RTP Protocol [RFC3550], the end system that source RTP RTP Protocol [RFC3550], the end system that runs an application
streams, an intermediate-system that forwards RTP packets to End- program that sends or receives RTP data packets, an intermediate-
devices or a third party that does not participate in the RTP session system that forwards RTP packets to End-devices or a third party that
(i.e., the third party monitor depicted in figure 1) can be observes the RTP and RTCP traffic but does not make itself visible to
envisioned to act as the Monitor within the RTP monitoring the RTP Session participants (i.e., the third party monitor depicted
architecture. in figure 1) can be envisioned to act as the monitor within the RTP
monitoring architecture. Note that the third party monitor should be
placed on the RTP/RTCP paths between the sender, intermediate and the
receiver.
The Metric Block exposes real time Application QoS/QoE metric The RTP Metric Block exposes real time Application QoS/QoE metric
information in the appropriate report block format to the management information in the appropriate report block format to the management
system within the RTP monitoring architecture. Such information can system (i.e., report collector) within the RTP monitoring
be formulated as: architecture. Such information can be formulated as:
o The direct metrics o The direct metrics
o or the composed metrics. o or the composed metrics
or formulated as or formulated as
o The Interval metrics o The Interval metrics
o or cumulative metrics o or cumulative metrics
o or sampled metrics. o or sampled metrics
Both the RTCP or RTCP XR can be extended to convey these metrics. Both the RTCP or RTCP XR can be extended to convey these metrics.
The details on transport protocols for metric blocks are described in The details on transport protocols for metric blocks are described in
Section 3.2. Section 3.2.
+-------------------+ +-------------------+
| RTP Sender | +----------+ | RTP Sender | 6 +----------+
| +-----------+ | |Management| | +-----------+ ||------------>|Management|
---------------->| Monitor |---------5------->| System | -------------->| Monitor |----| 6 | System |
| | | | | | | | | | | | |----------->| |
| | +-----------+ | +----------+ | | +-----------+ | | -------->| |
| |+-----------------+| | |+-----------------+| | | +-------/--+
| ||Application || --------------| | ||Application || | | -----------| |
| ||-Streaming video || | | | ||-Streaming video || | | | 1 | |6
| |---------|-VOIP || | +--------V------+ | |---------|-VOIP || | | | +--------V------+
| | ||-Video conference|| ------ Third Party | | | ||-Video conference|| | | --- Third Party |
| | ||-Telepresence || | Monitor | | | ||-Telepresence || | | | Monitor |
| | ||-Ad insertion || +---------------+ | | ||-Ad insertion || | 6| +---------------+
5 | |+-----------------+| 5 | |+-----------------+| | |
| | +-------------------+ | | +-------------------+ | |
| 1 | 1 | |
| | +Intermediate------------+ |-------------- ---- ----+ | | +Intermediate------------+ | | |------------------------+
| | | RTP System Report Block | RTP Receiver >--4-| | | | | RTP System | | | | RTP Receiver >--4-| |
| | | +---------- transported over| +-----------+ | | | | | +----------- | | | | +-----------+ |
| | | | RTCP extension | | Monitor |<-- | | | | | -----------| -------| | | |
|------------- Monitor |<--------5------|----| |<------| | | | | | | | | Monitor |<-- |
| | | | Report Block +----/------+ || |----------- Monitor |<--------5------|----| |<------|
| | +----------+ transported over | || | | | | Report Block | +----/------+ ||
| | RTCP XR | |2 || | | +----------+Transport Over | ||
| | +-----------------+ | | +-------/---------+ || | | RTCP XR or RTCP | |2 ||
| | |Application | | | |Application | || | | +-----------------+ extension | +-------/---------+ ||
| | |-Streaming video | | | |-Streaming video | || | | |Application | | | |Application | ||
| | |-VOIP | | 1 | |-VOIP | 3| | | |-Streaming video | | | |-Streaming video | ||
---->-Video conference|--------------->|-Video conference || | | |-VOIP | | 1 | |-VOIP | 3|
| |-Telepresence | | | |-Telepresence | || ---->-Video conference|--------------->|-Video conference ||
| |-Ad insertion | | | |-Ad insertion | || | |-Telepresence | | | |-Telepresence | ||
| +-----------------+ | | +-----------------+ || | |-Ad insertion | | | |-Ad insertion | ||
| +-----------------+ | | +-----------------+ || | +-----------------+ | | +-----------------+ ||
| |Transport | | | |Transport | || | +-----------------+ | | +-----------------+ ||
| |-IP/UDP/RTP | | | |-IP/UDP/RTP >---|| | |Transport | | | |Transport | ||
| |-IP/TCP/RTP | | | | -IP/TCP/RTP | | | |-IP/UDP/RTP | | | |-IP/UDP/RTP >---||
| |-IP/TCP/RTSP/RTP | | | |-IP/TCP/RTSP/RTP | | | |-IP/TCP/RTP | | | |-IP/TCP/RTP | |
| +-----------------+ | | +-----------------+ | | |-IP/TCP/RTSP/RTP | | | |-IP/TCP/RTSP/RTP | |
+------------------------+ +------------------------+ | +-----------------+ | | +-----------------+ |
+------------------------+ +------------------------+
Figure 1: RTP Monitoring Architecture Figure 1: RTP Monitoring Architecture
1. RTP communication between real time applications. 1. RTP communication between real time applications.
2. Application level metrics collection. 2. Application level metrics collection.
3. Transport level metrics collection. 3. Transport level metrics collection.
4. End System metrics collection. 4. End System metrics collection.
5. Reporting Session- metrics transmitted over specified interfaces. 5. Metrics Reporting over the RTP/RTCP paths
6. RTCP information Export to the network management system.
RTP is used to multicast groups, both ASM and SSM. These groups can
be monitored using RTCP. In the ASM case, the monitor is a member of
the multicast group and listens to RTCP XR reports from all members
of the ASM group. In the SSM case, there is a unicast feedback
target that receives RTCP feedback from receivers and distributes it
to other members of the SSM group (see figure 1 of RFC5760). The
monitor will need to be co-located with the feedback target to
receive all feedback from the receivers (this may also be an
intermediate system). In both ASM and SSM scenarios, receivers can
send RTCP XR reports to enhance the reception quality reporting.
3.2. RTCP Metric Block Report and associated parameters 3.2. RTCP Metric Block Report and associated parameters
The basic RTCP Reception Report (RR) [RFC3550] conveys reception The basic RTCP Reception Report (RR) [RFC3550] conveys reception
statistics (i.e., transport level statistics) in metric block report statistics (i.e., transport level statistics) in metric block report
format for multiple RTP media streams including format for multiple RTP media streams including
o the fraction of packet lost since the last report o the fraction of packet lost since the last report
o the cumulative number of packets lost o the cumulative number of packets lost
skipping to change at page 8, line 30 skipping to change at page 9, line 45
o an estimate of the inter-arrival jitter o an estimate of the inter-arrival jitter
o and information to allow senders to calculate the network round o and information to allow senders to calculate the network round
trip time. trip time.
The RTCP XRs [RFC3611] supplement the existing RTCP packets and The RTCP XRs [RFC3611] supplement the existing RTCP packets and
provide more detailed feedback on reception quality in several provide more detailed feedback on reception quality in several
categories: categories:
o Loss and duplicate RLE reports o Loss and duplicate Run Length Encoding (RLE) reports
o Packet-receipt times reports o Packet-receipt times reports
o Round-trip time reports o Round-trip time reports
o Statistics Summary Reports o Statistics Summary Reports
There are also various other scenarios in which it is desirable to There are also various other scenarios in which it is desirable to
send RTCP Metric reports more frequently. For example, the Audio/ send RTCP Metric reports more frequently. For example, the Audio/
Video Profile with Feedback [RFC4585] extends the standard A/V Video Profile with Feedback [RFC4585] extends the standard Audio/
Profile [RFC3551] to allow RTCP reports to be sent early provided Video Profile [RFC3551] to allow RTCP reports to be sent early
RTCP bandwidth allocation is respected. The following are four use provided RTCP bandwidth allocation is respected. The following are
cases but are not limited to: four use cases but are not limited to:
o RTCP NACK is used to provide feedback on the RTP sequence number o RTCP NACK is used to provide feedback on the RTP sequence number
of the lost packets [RFC4585]. on a subset of the lost packets or the total lost packets
[RFC4585].
o RTCP is extended to convey requests for full intra-coded frames or o RTCP is extended to convey requests for full intra-coded frames or
select the reference picture, and signal changes in the desired select the reference picture, and signal changes in the desired
temporal/spatial trade-off and maximum media bit rate [RFC5104]. temporal/spatial trade-off and maximum media bit rate [RFC5104].
o RTCP or RTCP XR is extended to provide feedback on ECN statistics o RTCP or RTCP XR is extended to provide feedback on Explicit
information [ECN]. Congestion Notification (ECN) statistics information [ECN].
o RTCP XR is extended to provide feedback on multicast acquisition o RTCP XR is extended to provide feedback on multicast acquisition
statistics information and parameters [RFC6332]. statistics information and parameters [RFC6332].
3.3. RTP Sender/Receiver entities located in network nodes 3.3. RTP Sender/Receiver entities located in network nodes
The location of the RTP Sender/Receiver entities may impact a set of The location of the RTP Sender/Receiver entities may impact a set of
meaningful metrics. For instance, application level metrics for QoE meaningful metrics. For instance, application level metrics for QoE
related performance parameters are usually measured at the user related performance parameters are under most conditions measured at
device in the home network. However in some cases, given the factors the user device that receives RTP data packets. However in some
("measurement point location", "measurement model location", cases, given the factors ( "measurement point location", "measurement
"awareness of content information" etc) taken into account, such model location", "awareness of content information", etc [P.NAMS])
metrics may be measured in a network node instead of a user device. taken into account, such metrics may be measured in a network node
instead of a user device.
4. Issues with reporting metric block using RTCP XR extension 4. Issues with reporting metric block using RTCP XR extension
Issues that have come up in the past with reporting metric block Issues that have come up in the past with reporting metric block
using RTCP XR extensions include (but are probably not limited to) using RTCP XR extensions include (but are probably not limited to)
the following: the following:
o Using large block. A single report block or metric is designed to o Using compound metrics block. A single report block
contain a large number of parameters in different classes for a (i.e.,compound metrics block) is designed to contain a large
specific application. For example, the RTCP Extended Reports number of parameters in different classes for a specific
(XRs) [RFC3611] defines seven report block formats for network application. For example, the RTCP Extended Reports (XRs)
[RFC3611] defines seven report block formats for network
management and quality monitoring. Some of these block types management and quality monitoring. Some of these block types
defined in the RTCP XRs [RFC3611] are only specifically designed defined in the RTCP XRs [RFC3611] are only specifically designed
for conveying multicast inference of network characteristics for conveying multicast inference of network characteristics
(MINC) or voice over IP (VoIP) monitoring. However different (MINC) or voice over IP (VoIP) monitoring. However different
applications layered on RTP may have different monitoring applications layered on RTP may have different monitoring
requirements. Design large block only for specific applications requirements. Design compound metrics block only for specific
may increase implementation cost and minimize interoperability. applications may increase implementation cost and minimize
interoperability.
o Correlating RTCP XR with the non-RTP data. CNAME defined in the o Correlating RTCP XR with the non-RTP data. Canonical End-Point
RTP Protocol [RFC3550] is an example of existing tool that allows Identifier SDES Item (CNAME) defined in the RTP Protocol [RFC3550]
to bind an SSRC that may change to a fixed source name in one RTP is an example of existing tool that allows to bind an
session. It may be also fixed across multiple RTP sessions from Synchronization source (SSRC) that may change to a fixed source
the same source. However there may be situations where RTCP name in one RTP session. It may be also fixed across multiple RTP
reports are sent to other participating endpoints using non-RTP sessions from the same source. However there may be situations
protocol in a session. For example, as described in the SIP RTCP where RTCP reports are sent to other participating endpoints using
Summary Report Protocol [RFC6035], the data contained in RTCP XR non-RTP protocol in a session. For example, as described in the
VoIP metrics reports [RFC3611] are forwarded to a central SIP RTCP Summary Report Protocol [RFC6035], the data contained in
RTCP XR VoIP metrics reports [RFC3611] are forwarded to a central
collection server systems using SIP. In such case, there is a collection server systems using SIP. In such case, there is a
large portfolio of quality parameters that can be associated with large portfolio of quality parameters that can be associated with
real time application, e.g., VOIP application, but only a minimal real time application, e.g., VOIP application, but only a minimal
number of parameters are included on the RTCP-XR reports. number of parameters are included on the RTCP-XR reports.
Therefore correlation between RTCP XR and non-RTP data should be Therefore correlation between RTCP XR and non-RTP data should be
concerned if administration or management systems need to rely on concerned if administration or management systems need to rely on
the mapping RTCP statistics to non-RTCP measurements to conducts the mapping RTCP statistics to non-RTCP measurements to conducts
data analysis and creates alerts to the users. Without such data analysis and creates alerts to the users. Without such
correlation, it is hard to provide accurate measures of real time correlation, it is hard to provide accurate measures of real time
application quality with a minimal number of parameters included application quality with a minimal number of parameters included
skipping to change at page 12, line 31 skipping to change at page 13, line 31
conditions. However there are many metrics available. It is likely conditions. However there are many metrics available. It is likely
that different applications or classes of applications will wish to that different applications or classes of applications will wish to
use different metrics. Any one application is likely to require use different metrics. Any one application is likely to require
metrics for more than one parameter but if this is the case, metrics for more than one parameter but if this is the case,
different applications will almost certainly require different different applications will almost certainly require different
combinations of metrics. If larger blocks are defined containing combinations of metrics. If larger blocks are defined containing
multiple metrics to address the needs of each application, it becomes multiple metrics to address the needs of each application, it becomes
likely that many different such larger blocks are defined, which likely that many different such larger blocks are defined, which
becomes a danger to interoperability. becomes a danger to interoperability.
To avoid this pitfall, this memo proposes the use of small RTCP XR To avoid this pitfall, this memo proposes the use of single metrics
metrics blocks each containing a very small number of individual blocks each containing a very small number of individual metrics
metrics characterizing only one parameter of interest to an characterizing only one parameter of interest to an application
application running over RTP. For example, at the RTP transport running over RTP. For example, at the RTP transport layer, the
layer, the parameter of interest might be packet delay variation, and parameter of interest might be packet delay variation, and
specifically the metric "IPDV" defined by [Y1540]. See Section 6 for specifically the metric "IP Packet Delay Variation (IPDV)" defined by
architectural considerations for a metrics block, using as an example [Y1540]. See Section 6 for architectural considerations for a
a metrics block to report packet delay variation. metrics block, using as an example a metrics block to report packet
delay variation.
5.2. Correlating RTCP XR with the non-RTP data 5.2. Correlating RTCP XR with the non-RTP data
There may be situation where more than one media transport protocols There may be situation where more than one media transport protocols
are used by one application to interconnect to the same session in are used by one application to interconnect to the same session in
the gateway. For example, one RTCP XR Packet is sent to the the gateway. For example, one RTCP XR Packet is sent to the
participating endpoints using non- RTP-based media transport (e.g., participating endpoints using non-RTP-based media transport (e.g.,
using SIP) in a VOIP session, one crucial factor lies in how to using SIP) in a VOIP session, one crucial factor lies in how to
handle their different identities that are corresponding to different handle their different identities that are corresponding to different
media transport. media transport.
This memo proposes an approach to facilitate the correlation of the This memo proposes an approach to facilitate the correlation of the
RTCP Session with other session-related non-RTP data. That is to say RTCP Session with other session-related non-RTP data. That is to say
if there is a need to correlate RTP sessions with non-RTP sessions, if there is a need to correlate RTP sessions with non-RTP sessions,
then the correlation information needed should be conveyed in a new then the correlation information needed should be conveyed in a new
RTCP Source Description (SDES) item ,since such correlation RTCP Source Description (SDES) item, since such correlation
information describes the source, rather than providing a quality information describes the source, rather than providing a quality
report. An example use case is for a participant endpoint may convey report. An example use case is for a participant endpoint may convey
a call identifier or a global call identifier associated with the a call identifier or a global call identifier associated with the
SSRC of measured RTP stream . In such case, the participant endpoint SSRC of measured RTP stream. In such case, the participant endpoint
uses the SSRC of source to bind the call identifier using SDES item uses the SSRC of source to bind the call identifier using SDES item
in the SDES RTCP packet and send such correlation to the network in the SDES RTCP packet and send such correlation to the network
management system. A flow measurement tool that is configured with management system. A flow measurement tool that is configured with
the 5-tuple and not call-aware then forward the RTCP XR reports along the 5-tuple and not call-aware then forward the RTCP XR reports along
with the SSRC of the measured RTP stream which is included in the XR with the SSRC of the measured RTP stream which is included in the XR
Block header and 5-tuple to the network management system. Network Block header and 5-tuple to the network management system. Network
management system can then correlate this report using SSRC with management system can then correlate this report using SSRC with
other diagnostic information such as call detail records. other diagnostic information such as call detail records.
5.3. Reducing Measurement information repetition 5.3. Reducing Measurement information repetition
When multiple metric blocks are carried in one RTCP XR packet, When multiple metric blocks are carried in one RTCP XR packet,
reporting on the same stream from the same source for the same time reporting on the same stream from the same source for the same time
period, RTCP should use the SSRC to identify and correlate the period, RTCP should use the SSRC to identify and correlate the
multiple metric blocks between metric blocks. This memo proposes to multiple metric blocks between metric blocks. This memo proposes to
define a new XR Block that will be used to convey the common time define a new XR Block that will be used to convey the common time
period and the number of packets sent during this period [MI]. If period and the number of packets sent during this period. If the
the measurement interval for a metric is different from the RTCP measurement interval for a metric is different from the RTCP
reporting interval, then this measurement duration in the [MI] SHOULD reporting interval, then this measurement duration in the Measurement
be used to specify the interval. When there may be multiple information block [MI] should be used to specify the interval. When
measurements information blocks with the same SSRC in one RTCP XR there may be multiple measurements information blocks with the same
compound packet, the measurement information block should be put in SSRC in one RTCP XR compound packet, the measurement information
order and followed by all the metric blocks associated with this block should be put in order and followed by all the metric blocks
measurement information block. New RTCP XR metric blocks that rely associated with this measurement information block. New RTCP XR
on the Measurement information block [MI] MUST specify the response metric blocks that rely on the Measurement information block [MI]
in case the new RTCP XR metric block is received without an must specify the response in case the new RTCP XR metric block is
associated measurement information block; in most cases, it is received without an associated measurement information block. In
expected that the correct response is to discard the received metric. most cases, it is expected that the correct response is to discard
In order to reduce measurement information repetition in one RTCP XR the received metric. In order to reduce measurement information
compound packet containing multiple metric blocks, the measurement repetition in one RTCP XR compound packet containing multiple metric
information shall be sent before the related metric blocks that are blocks, the measurement information shall be sent before the related
from the same reporting interval. Note that for packet loss metric blocks that are from the same reporting interval. Note that
robustness if the report blocks for the same interval span over more for packet loss robustness if the report blocks for the same interval
than one RTCP packet then each must have the measurement identity span over more than one RTCP packet then each must have the
information even if though they will be the same. measurement identity information even if though they will be the
same.
5.4. Expanding the RTCP XR block namespace 5.4. Expanding the RTCP XR block namespace
The consumption of XR block code points isn't a major issue. However The consumption of XR block code points isn't a major issue. However
if XR block codes points is really close to run out of space, it if XR block codes points is really close to run out of space, it
might be desirable to define new fields in the XR report block or might be desirable to define new fields in the XR report block or
define one XR block type for vendor-specific extensions, with an define one XR block type for vendor-specific extensions, with an
enterprise number included to identify the vendor making the enterprise number included to identify the vendor making the
extension. extension.
6. An example of a metric block 6. An example of a metric block
This section uses the example of an existing proposed metrics block This section uses the example of an existing proposed metrics block
to illustrate the application of the principles set out in to illustrate the application of the principles set out in
Section 5.1. Section 5.1.
The example [PDV] is a block to convey information about packet delay The example [PDV] is a block to convey information about packet delay
variation (PDV) only, consistent with the principle that a metrics variation (PDV) only, consistent with the principle that a metrics
block should address only one parameter of interest. One simple block should address only one parameter of interest. One simple
metric of PDV is available in the RTCP RR packet as the "interarrival metric of PDV is available in the RTCP RR packet as the "interarrival
jitter" field. There are other PDV metrics which may be more useful jitter" field. There are other PDV metrics with a certain similarity
to certain applications. Two such metrics are the IPDV metric in metric structure which may be more useful to certain applications.
([Y1540], [RFC3393]) and the MAPDV2 metric [G1020]. Use of these Two such metrics are the IPDV metric ([Y1540], [RFC3393]) and the
metrics is consistent with the principle in Section 5 of RTCP mean absolute packet delay variation 2 (MAPDV2) metric [G1020]. Use
guideline [RFC5968] that metrics should usually be defined elsewhere, of these metrics is consistent with the principle in Section 5 of
so that RTCP standards define only the transport of the metric rather RTCP guideline [RFC5968] that metrics should usually be defined
than its nature. The purpose of this section is to illustrate the elsewhere, so that RTCP standards define only the transport of the
architecture using the example of [PDV] rather than to document the metric rather than its nature. The purpose of this section is to
design of the PDV metrics block or to provide a tutorial on PDV in illustrate the architecture using the example of [PDV] rather than to
general. document the design of the PDV metrics block or to provide a tutorial
on PDV in general.
Given the availability of at least three metrics for PDV, there are Given the availability of at least three metrics for PDV, there are
design options for the allocation of metrics to RTCP XR blocks: design options for the allocation of metrics to RTCP XR blocks:
o provide an RTCP XR block per metric o provide an RTCP XR block per metric
o provide a single RTCP XR block which contains all three metrics o provide a single RTCP XR block which contains all three metrics
o provide a single RTCP block to convey any one of the three o provide a single RTCP block to convey any one of the three
metrics, together with a identifier to inform the receiving RTP metrics, together with a identifier to inform the receiving RTP
skipping to change at page 15, line 47 skipping to change at page 16, line 48
In choosing between these options, extensibility is important, In choosing between these options, extensibility is important,
because additional metrics of PDV may well be standardized and because additional metrics of PDV may well be standardized and
require inclusion in this framework. The first option is extensible require inclusion in this framework. The first option is extensible
but only by use of additional RTCP XR blocks, which may consume the but only by use of additional RTCP XR blocks, which may consume the
limited namespace for RTCP XR blocks at an unacceptable rate. The limited namespace for RTCP XR blocks at an unacceptable rate. The
second option is not extensible, so could be rejected on that basis, second option is not extensible, so could be rejected on that basis,
but in any case a single application is quite unlikely to require but in any case a single application is quite unlikely to require
transport of more than one metric for PDV. Hence the third option transport of more than one metric for PDV. Hence the third option
was chosen. This implies the creation of a subsidiary namespace to was chosen. This implies the creation of a subsidiary namespace to
enumerate the PDV metrics which may be transported by this block, as enumerate the PDV metrics which may be transported by this block, as
discussed further in [PDV] . discussed further in [PDV].
7. Application to RFC 5117 topologies 7. Application to RFC 5117 topologies
The topologies specified in [RFC5117] fall into two categories. The The topologies specified in [RFC5117] fall into two categories. The
first category relates to the RTP system model utilizing multicast first category relates to the RTP system model utilizing multicast
and/or unicast. The topologies in this category are specifically and/or unicast. The topologies in this category are specifically
Topo-Point-to-Point, Topo- Multicast, Topo-Translator (both variants, Topo-Point-to-Point, Topo- Multicast, Topo-Translator (both variants,
Topo-Trn-Translator and Topo-Media-Translator, and combinations of Topo-Trn-Translator and Topo-Media-Translator, and combinations of
the two), and Topo-Mixer. These topologies use RTP end systems, RTP the two), and Topo-Mixer. These topologies use RTP end systems, RTP
mixers and RTP translators defined in the RTP protocol [RFC3550]. mixers and RTP translators defined in the RTP protocol [RFC3550].
For purposes of reporting connection quality to other RTP systems, For purposes of reporting connection quality to other RTP systems,
RTP mixers and RTP end systems are very similar. Mixers RTP mixers and RTP end systems are very similar. Mixers
resynchronize packets and do not relay RTCP reports received from one resynchronize packets and do not relay RTCP reports received from one
cloud towards other cloud(s). Translators do not resynchronize cloud towards other cloud(s). Translators do not resynchronize
packets and SHOULD forward certain RTCP reports between clouds. In packets and should forward certain RTCP reports between clouds. In
this category, the RTP system (end system, mixer or translator) which this category, the RTP system (end system, mixer or translator) which
originates, terminates or forwards RTCP XR blocks is expected to originates, terminates or forwards RTCP XR blocks is expected to
handle RTCP, including RTCP XR, according to the RTP protocol handle RTCP, including RTCP XR, according to the RTP protocol
[RFC3550]. Provided this expectation is met, an RTP system using [RFC3550]. Provided this expectation is met, an RTP system using
RTCP XR is architecturally no different from an RTP system of the RTCP XR is architecturally no different from an RTP system of the
same class (end system, mixer, or translator) which does not use RTCP same class (end system, mixer, or translator) which does not use RTCP
XR. The second category relates to deployed system models used in XR. The second category relates to deployed system models used in
many H.323 [H323] video conferences. The topologies in this category many H.323 [H323] video conferences. The topologies in this category
are Topo-Video-Switch-MCU and Topo-RTCP-terminating-MCU. Such are Topo-Video-Switch-MCU and Topo-RTCP-terminating-MCU. Such
topologies based on systems do not behave according to the RTP topologies based on systems do not behave according to the RTP
skipping to change at page 20, line 9 skipping to change at page 21, line 9
Also note that the third party monitors are not visible at the RTP Also note that the third party monitors are not visible at the RTP
layer since they do not send any RTCP packets. In order to prevent layer since they do not send any RTCP packets. In order to prevent
any sensitive information leakage, the monitoring from the third any sensitive information leakage, the monitoring from the third
party monitors should be prohibited unless the security is in place party monitors should be prohibited unless the security is in place
to authenticate them. to authenticate them.
10. Acknowledgement 10. Acknowledgement
The authors would also like to thank Colin Perkins, Graeme Gibbs, The authors would also like to thank Colin Perkins, Graeme Gibbs,
Debbie Greenstreet, Keith Drage, Dan Romascanu, Ali C. Begen, Roni Debbie Greenstreet, Keith Drage, Dan Romascanu, Ali C. Begen, Roni
Even, Magnus Westerlundfor their valuable comments and suggestions on Even, Magnus Westerlund for their valuable comments and suggestions
the early version of this document. on the early version of this document.
11. Informative References 11. Informative References
[ECN] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P., [ECN] Westerlund, M., Johansson, I., Perkins, C., O'Hanlon, P.,
and K. Carlberg, "Explicit Congestion Notification (ECN) and K. Carlberg, "Explicit Congestion Notification (ECN)
for RTP over UDP", ID draft-ietf-avtcore-ecn-for-rtp-04, for RTP over UDP", ID draft-ietf-avtcore-ecn-for-rtp-06,
July 2011. February 2012.
[G1020] ITU-T, "ITU-T Rec. G.1020, Performance parameter [G1020] ITU-T, "ITU-T Rec. G.1020, Performance parameter
definitions for quality of speech and other voiceband definitions for quality of speech and other voiceband
applications utilizing IP networks", July 2006. applications utilizing IP networks", July 2006.
[H323] ITU-T, "ITU-T Rec. H.323, Packet-based multimedia [H323] ITU-T, "ITU-T Rec. H.323, Packet-based multimedia
communications systems", June 2006. communications systems", June 2006.
[MI] Wu, Q., "Measurement Identity and information Reporting [MI] 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-01, ID draft-ietf-xrblock-rtcp-xr-meas-identity-02,
October 2011. January 2012.
[MQ] Wu, Q., Zorn, G., Schott, R., and K. Lee, "RTCP XR Blocks [P.NAMS] ITU-T, "Non-intrusive parametric model for the Assessment
for multimedia quality metric reporting", of performance of Multimedia Streaming", ITU-T
ID draft-wu-xrblock-rtcp-xr-quality-monitoring-02, Recommendation P.NAMS, November 2009.
May 2011.
[PDV] Hunt, G., "RTCP XR Report Block for Packet Delay Variation [PDV] Hunt, G., Clark, A., and Q. Wu, "RTCP XR Report Block for
Metric Reporting", ID draft-ietf-xrblock-rtcp-xr-pdv-00, Packet Delay Variation Metric Reporting",
September 2011. ID draft-ietf-xrblock-rtcp-xr-pdv-02, December 2011.
[QOE] Hunt, G., Clark, A., Wu, Q., Schott, R., and G. Zorn,
"RTCP XR Blocks for QoE Metric Reporting",
ID draft-ietf-xrblock-rtcp-xr-qoe-00, February 2012.
[RFC1122] Braden, R., "Requirements for Internet Hosts -- [RFC1122] Braden, R., "Requirements for Internet Hosts --
Communication Layers", RFC 1122, October 1989. Communication Layers", RFC 1122, October 1989.
[RFC2959] Baugher, M., Strahm, B., and I. Suconick, "Real-Time
Transport Protocol Management Information Base", RFC 2959,
October 2000.
[RFC3393] Demichelis, C., "IP Packet Delay Variation Metric for IP [RFC3393] Demichelis, C., "IP Packet Delay Variation Metric for IP
Performance Metrics (IPPM)", RFC 3393, November 2002. Performance Metrics (IPPM)", RFC 3393, November 2002.
[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.
[RFC3551] Schulzrinne , H. and S. Casner, "Extended RTP Profile for [RFC3551] Schulzrinne , H. and S. Casner, "Extended RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/AVPF)", RFC 3551, July 2003. (RTP/AVPF)", RFC 3551, July 2003.
skipping to change at page 22, line 22 skipping to change at page 23, line 29
Control Protocol (RTCP)", RFC 5968, September 2010. Control Protocol (RTCP)", RFC 5968, September 2010.
[RFC6035] Pendleton, A., Clark, A., Johnston, A., and H. Sinnreich, [RFC6035] Pendleton, A., Clark, A., Johnston, A., and H. Sinnreich,
"Session Initiation Protocol Event Package for Voice "Session Initiation Protocol Event Package for Voice
Quality Reporting", RFC 6035, November 2010. Quality Reporting", RFC 6035, November 2010.
[RFC6332] Begen, A. and E. Friedrich, "Multicast Acquisition Report [RFC6332] Begen, A. and E. Friedrich, "Multicast Acquisition Report
Block Type for RTP Control Protocol (RTCP) Extended Block Type for RTP Control Protocol (RTCP) Extended
Reports (XRs)", RFC 6332, July 2011. Reports (XRs)", RFC 6332, July 2011.
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New
Performance Metric Development", RFC 6390, October 2011.
[Y1540] ITU-T, "ITU-T Rec. Y.1540, IP packet transfer and [Y1540] 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. 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-avtcore-monarch-00 A.1. draft-ietf-avtcore-monarch-00
skipping to change at page 26, line 5 skipping to change at page 26, line 43
o Add one new section to clarify where to measure QoE related o Add one new section to clarify where to measure QoE related
parameters. parameters.
o Add text in section 5.3 to clarify the failure case when o Add text in section 5.3 to clarify the failure case when
measurement interval is not sent. measurement interval is not sent.
o Add text in section 5.3 to clarify how to deal with multiple o Add text in section 5.3 to clarify how to deal with multiple
measurements information blocks carried in the same packet. measurements information blocks carried in the same packet.
A.11. draft-ietf-avtcore-monarch-10
The following are the major changes compared to 09:
o Discuss what exist already for monitoring in section 3.1.
o Provide benefit using RTCP XR based monitoring in section 3.1.
o add one new paragraph in section 3.1 to describe how monitoring
architecture is applied to ASM/SSM.
o Other Editorial Changes.
Authors' Addresses Authors' Addresses
Qin Wu (editor) Qin Wu (editor)
Huawei Huawei
101 Software Avenue, Yuhua District 101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012 Nanjing, Jiangsu 210012
China China
Email: sunseawq@huawei.com Email: sunseawq@huawei.com
 End of changes. 50 change blocks. 
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