draft-ietf-avtcore-monarch-01.txt   draft-ietf-avtcore-monarch-02.txt 
Audio/Video Transport Working Group Q. Wu Audio/Video Transport Working Group Q. Wu, Ed.
Internet-Draft Huawei Internet-Draft Huawei
Intended status: Informational May 5, 2011 Intended status: Informational G. Hunt
Expires: November 6, 2011 Expires: November 28, 2011 Unaffiliated
P. Arden
BT
May 27, 2011
Monitoring Architectures for RTP Monitoring Architectures for RTP
draft-ietf-avtcore-monarch-01.txt draft-ietf-avtcore-monarch-02.txt
Abstract Abstract
This memo proposes an architecture for extending RTCP with a new RTCP This memo proposes an architecture for extending RTCP with a new RTCP
XR (RFC3611) block type to report new metrics regarding media XR (RFC3611) block type to report new metrics regarding media
transmission or reception quality, as proposed in RFC5968. This memo transmission or reception quality, as proposed in RFC5968. This memo
suggests that a new block should contain a single metric or a small suggests that a new block should contain a single metric or a small
number of metrics relevant to a single parameter of interest or number of metrics relevant to a single parameter of interest or
concern, rather than containing a number of metrics which attempt to concern, rather than containing a number of metrics which attempt to
provide full coverage of all those parameters of concern to a provide full coverage of all those parameters of concern to a
skipping to change at page 1, line 41 skipping to change at page 1, line 44
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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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 November 6, 2011. This Internet-Draft will expire on November 28, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements notation . . . . . . . . . . . . . . . . . . . . 4 2. Requirements notation . . . . . . . . . . . . . . . . . . . . 4
3. RTP monitoring architecture . . . . . . . . . . . . . . . . . 5 3. RTP monitoring architecture . . . . . . . . . . . . . . . . . 5
3.1. Interaction with Management Application . . . . . . . . . 7 3.1. RTCP Metric Block Report and associated parameters . . . . 7
3.2. RTCP Metric Block Report and associated parameters . . . . 7
4. Issues with reporting metric block using RTCP XR extension . . 9 4. Issues with reporting metric block using RTCP XR extension . . 9
5. Guideline for reporting block format using RTCP XR . . . . . . 10 5. Guideline for reporting block format using RTCP XR . . . . . . 10
5.1. Using small blocks . . . . . . . . . . . . . . . . . . . . 10 5.1. Using small blocks . . . . . . . . . . . . . . . . . . . . 10
5.2. Sharing the identity block . . . . . . . . . . . . . . . . 10 5.2. Sharing the identity information . . . . . . . . . . . . . 10
6. An example of a metric block . . . . . . . . . . . . . . . . . 15 5.3. Correlating identity information with the data . . . . . . 12
7. Application to RFC 5117 topologies . . . . . . . . . . . . . . 16 6. An example of a metric block . . . . . . . . . . . . . . . . . 13
7.1. Applicability to MCU . . . . . . . . . . . . . . . . . . . 16 7. Application to RFC 5117 topologies . . . . . . . . . . . . . . 14
7.2. Applicability to Translators . . . . . . . . . . . . . . . 16 7.1. Applicability to MCU . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 7.2. Applicability to Translators . . . . . . . . . . . . . . . 14
9. Security Considerations . . . . . . . . . . . . . . . . . . . 19 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 20 9. Security Considerations . . . . . . . . . . . . . . . . . . . 17
11. Informative References . . . . . . . . . . . . . . . . . . . . 21 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 18
Appendix A. Appendix A. Change Log . . . . . . . . . . . . . . . 22 11. Informative References . . . . . . . . . . . . . . . . . . . . 19
A.1. draft-ietf-avtcore-monarch-00 . . . . . . . . . . . . . . 22 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 20
A.2. draft-ietf-avtcore-monarch-01 . . . . . . . . . . . . . . 22 A.1. draft-ietf-avtcore-monarch-00 . . . . . . . . . . . . . . 20
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 23 A.2. draft-ietf-avtcore-monarch-01 . . . . . . . . . . . . . . 20
A.3. draft-ietf-avtcore-monarch-02 . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
Service providers and network providers today suffer from lack of
good service that can monitor the performance at the user's home,
handset or remote office. Without service performance metrics, it is
difficult for network operators to properly locate the problem and
solve service issues before problems impact subscriber/end user. The
resolution generally involves deploying costly field network
technician to conduct on-site troubleshooting and diagnostics. By
reducing the expensive deployments with more automated remote
monitoring capabilities, network operators can save significant
costs, reduce mean time to repair and provide a better service
offering.
As more users and subscribers rely on real time application services, As more users and subscribers rely on real time application services,
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 RTCP XR [RFC3611]and other RTCP extension to
Sender Reports(SR), Receiver Reports (RR) [RFC3550]are being Sender Reports(SR), Receiver Reports (RR) [RFC3550]are being
developed for the purpose of collecting and reporting performance developed for the purpose of collecting and reporting performance
metrics from endpoint devices that can be used to correlate the metrics from endpoint devices that can be used to correlate the
metrics, provide end to end service visibility and measure and metrics, provide end to end service visibility and measure and
monitor QoE. monitor QoE.
skipping to change at page 5, line 29 skipping to change at page 5, line 29
of monitor in RFC3550, the end system that source RTP streams, an of monitor in RFC3550, the end system that source RTP streams, an
intermediate-system that forwards RTP packets to End-devices or a intermediate-system that forwards RTP packets to End-devices or a
third party that does not participate RTP session (i.e., the third third party that does not participate RTP session (i.e., the third
party monitor depicted in figure 1) can be envisioned to act as party monitor depicted in figure 1) can be envisioned to act as
Monitor within the RTP monitoring architecture. Monitor within the RTP monitoring architecture.
The Metric Block exposes real time Application Quality information in The Metric Block exposes real time Application Quality information in
the appropriate report block format to monitor within the RTP the appropriate report block format to monitor within the RTP
monitoring architecture. Both the RTCP or RTCP XR can be extended to monitoring architecture. Both the RTCP or RTCP XR can be extended to
convey such information. The details on transport protocol for convey such information. The details on transport protocol for
metric block is described in Section 3.2. metric block is described in Section 3.1.
|---------------+ |---------------+
| Management | | Management |
+-------------------+ | System | +-------------------+ | System |
| RTP Sender | | +----------+ | | RTP Sender | | +----------+ |
| +-----------+ | | | | | | +-----------+ | | | | |
---------------->| Monitor |---------5------->| Monitor | | ---------------->| Monitor |---------5------->| Monitor | |
| | | | | | | | | | | | | | | | | |
| | +-----------+ | | +----\-----+ | | | +-----------+ | | +----\-----+ |
| |+-----------------+| | | | | |+-----------------+| | | |
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1. RTP communication between real time applications 1. RTP communication between real time applications
2. Application level metrics 2. Application level metrics
3. Transport level metrics 3. Transport level metrics
4. End System metrics 4. End System metrics
5. Reporting Session- metrics transmitted over specified interfaces 5. Reporting Session- metrics transmitted over specified interfaces
3.1. Interaction with Management Application 3.1. RTCP Metric Block Report and associated parameters
The full solution may include Management application which interacts
with monitor. The Monitor outputs reports to the management
application. The management application collects raw data from
monitor, organizes database, conducts data analysis and creates
alerts to the users. However Management application interaction with
Monitor is out of scope of this document.
3.2. RTCP Metric Block Report and associated parameters
The basic RTCP Reception Report (RR) conveys reception statistics in The basic RTCP Reception Report (RR) conveys reception statistics in
metric block report format for multiple RTP media streams including metric block report format for multiple RTP media streams including
o transport level statistics o transport level statistics
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
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specific application. For example, RFC 3611 [RFC3611] defines specific application. For example, RFC 3611 [RFC3611] defines
seven report block formats for network management and quality seven report block formats for network management and quality
monitoring. However some of these block types defined in monitoring. However some of these block types defined in
[RFC3611] are only specifically designed for conveying multicast [RFC3611] are only specifically designed for conveying multicast
inference of network characteristics(MINC) or voice over IP (VoIP) inference of network characteristics(MINC) or voice over IP (VoIP)
monitoring. However different applications layered on RTP may monitoring. However different applications layered on RTP may
have some monitoring requirements in common, design large block have some monitoring requirements in common, design large block
only for specific applications may increase implementation cost only for specific applications may increase implementation cost
and minimize interoperability. and minimize interoperability.
o Identity Information duplication. When multiple small blocks in o Identity Information duplication. There may be situations where
the same RTCP XR packet contain measurement data for the same an RTCP XR packet containing more than two metrics blocks, reports
stream and period, it bring inefficiency to Repeat the information on the same streams from the same source. In such case, each
in a number of metrics blocks within the same RTCP packet. metric block should have the same measurement identity, if each
metric block carry such duplicated data for the measurement,it
leads to redundant information in this design since equivalent
information is provided multiple times, once in *every*
identification packet. Though this ensures immunity to packet
loss, the design bring more complexity and the overhead is not
completely trivial.
o Metric Blocks association. When an RTCP XR packet containing four o Metric Blocks association. There may be situations where an RTCP
metrics blocks, reporting on streams from two sources, two XR packet containing four metrics blocks, reports on streams from
identity blocks need to be added into the RTCP XR packet to two sources. In such case, two identity blocks need to be added
correlate two sources if identity information is allowed separate into the RTCP XR packet to correlate two sources if identity
from each metric block as one independent block. However how to information is allowed separate from each metric block as one
associate identity block with relevant metric block is a problem, independent block. However how to associate identity block with
relevant metric block data or other identity data is a problem,
e.g., all identity blocks are following all the metric block or e.g., all identity blocks are following all the metric block or
vice versa make one receiving RTCP XR packet hard to distinguish vice versa make one receiving RTCP XR packet hard to distinguish
from which metric block belong to which source. from which metric block belong to which source.
5. Guideline for reporting block format using RTCP XR 5. Guideline for reporting block format using RTCP XR
5.1. Using small blocks 5.1. Using small blocks
Different applications using RTP for media transport certainly have Different applications using RTP for media transport certainly have
differing requirements for metrics transported in RTCP to support differing requirements for metrics transported in RTCP to support
skipping to change at page 10, line 40 skipping to change at page 10, line 40
To avoid this pitfall, this memo proposes the use of small RTCP XR To avoid this pitfall, this memo proposes the use of small RTCP XR
metrics blocks each containing a very small number of individual metrics blocks each containing a very small number of individual
metrics characterizing only one parameter of interest to an metrics characterizing only one parameter of interest to an
application running over RTP. For example, at the RTP transport application running over RTP. For example, at the RTP transport
layer, the parameter of interest might be packet delay variation, and layer, the parameter of interest might be packet delay variation, and
specifically the metric "IPDV" defined by [Y1540]. See Section 6 for specifically the metric "IPDV" defined by [Y1540]. See Section 6 for
architectural considerations for a metrics block, using as an example architectural considerations for a metrics block, using as an example
a metrics block to report packet delay variation. a metrics block to report packet delay variation.
5.2. Sharing the identity block 5.2. Sharing the identity information
Any measurement must be identified. However if metrics are delivered Any measurement must be identified. However if metrics are delivered
in small blocks there is a danger of inefficiency arising from in small blocks there is a danger of inefficiency arising from
repeating this information in a number of metrics blocks within the repeating this information in a number of metrics blocks within the
same RTCP packet, in cases where the same identification information same RTCP packet, in cases where the same identification information
applies to multiple metrics blocks. applies to multiple metrics blocks.
An instance of a metric must be identified using information which is An instance of a metric must be identified using information which is
likely to include most of the following: likely to include most of the following:
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information in this design since equivalent information is provided information in this design since equivalent information is provided
multiple times, once in *every* identification packet. Though this multiple times, once in *every* identification packet. Though this
ensures immunity to packet loss, the design bring more complexity and ensures immunity to packet loss, the design bring more complexity and
the overhead is not completely trivial. the overhead is not completely trivial.
This section proposes an approach to minimise the inefficiency of This section proposes an approach to minimise the inefficiency of
providing this identification information, assuming that an providing this identification information, assuming that an
architecture based on small blocks means that a typical RTCP packet architecture based on small blocks means that a typical RTCP packet
will contain more than one metrics block needing the same will contain more than one metrics block needing the same
identification. The choice of identification information to be identification. The choice of identification information to be
provided is discussed in [IDENTITY] . provided is discussed in [IDENTITY]. The approach is to define a
stand-alone block containing only identification information within
The approach is to define a stand-alone block containing only the scope of the containing RTCP XR packet. The "containing RTCP XR
identification information, and to tag this identification block with packet" is defined here as the RTCP XR header with PT=XR=207 defined
a number which is unique within the scope of the containing RTCP XR in Section 2 of [RFC3611] and the associated payload defined by the
packet. The "containing RTCP XR packet" is defined here as the RTCP length field of this RTCP XR header. The RTCP XR header itself
XR header with PT=XR=207 defined in Section 2 of [RFC3611] and the includes the SSRC of the node at which all of the contained metrics
associated payload defined by the length field of this RTCP XR were measured, hence this SSRC need not be repeated in the stand-
header. The RTCP XR header itself includes the SSRC of the node at alone identification block. A single containing RTCP XR packet may
which all of the contained metrics were measured, hence this SSRC contain multiple identification blocks limited by the range of the
need not be repeated in the stand-alone identification block. A tag field. Typically there will be one identification block per
single containing RTCP XR packet may contain multiple identification monitored source SSRC, but the use of more than one identification
blocks limited by the range of the tag field. Typically there will block for a single monitored source SSRC within a single containing
be one identification block per monitored source SSRC, but the use of RTCP XR packet is not ruled out. In order to reduce overhead of the
more than one identification block for a single monitored source SSRC payload, This stand-alone block need only be exchanged occasionally,
within a single containing RTCP XR packet is not ruled out. for example sent once at the start of a session.
There will be zero or more metrics blocks dependent on each
identification block. The dependence of an instance of a metrics
block on an identification block is established by the metrics
block's having the same numeric value of the tag field as its
identification block (in the same containing RTCP XR packet).
Figure 2 below illustrates this principle using as an example an RTCP
XR packet containing four metrics blocks, reporting on streams from
two sources. The measurement identity information is provided in two
blocks with Block Type NMI, and tag values 0 and 1 respectively.
Note: in this example, RTCP XR block type values for four proposed
new block types (work in progress) are given as NMI, NPDV, NBGL and
NDEL.
Each of these two identity blocks will specify the SSRC of one of the
monitored streams, as well as information about the span of the
measurement. There are two metrics blocks with tag=0 indicating
their association with the measurement identity block which also has
tag=0. These are the two blocks following the identity block with
tag=0, though this positioning is not mandatory. There are also two
metrics blocks with tag=1 indicating their association with the
measurement identity block which also has tag=1, and these are the
two blocks following the identity block with tag=1.
Note that if metrics blocks associated with an identity block must
always follow the identity block, we could save the tag field and
possibly simplify processing. However depending on ordering of
metric block and identity block may bring inefficiency since you do
not know which block is the last metric block associated with
identity block unless you identify the next identity block. Hence it
is more desirable to to do cross-referencing with a numeric tag,i.e.,
using tag field to associated metric block with identity block.
In the example, the block types of the metrics blocks associated with
tag=0 are BT=NPDV (a PDV metrics block) and BT=NBGL (a burst and gap
loss metrics block). The block types of the metrics blocks
associated with tag=1 are BT=NPDV (a second PDV metrics block) and
BT=NDEL (a delay metrics block). This illustrates that:
o multiple instances of the same metrics block may occur within a
containing RTCP XR packet, associated with different
identification information, and
o differing measurements may be made, and reported, for the 5.3. Correlating identity information with the data
different streams arriving at an RTP system.
0 1 2 3 This section proposes an approach to facilitate the correlation of
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 the metrics report blocks with other session-related data or identity
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ data, i.e., using correlation tag to associate identity information
|V=2|P|reserved | PT=XR=207 | length | with the data.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of RTCP XR packet sender |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NMI |0|tag=0| resv | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of stream source 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...measurement identity information, source 1... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NPDV |I|tag=0|pdvtyp | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...PDV information for source 1... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NBGL |I|tag=0| resv | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...burst-gap-loss information for source 1... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NMI |0|tag=1| resv | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of stream source 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...measurement identity information, source 2... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NPDV |I|tag=1|pdvtyp | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...PDV information for source 2... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=NDEL |I|tag=1| resv | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...delay information for source 2... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: RTCP XR block with identity blocks For example, there will be zero or more metrics blocks dependent on
the same set of identity information. The dependence of an instance
of a metrics block on such identity information can be established by
the metrics block's having the same numeric value of the tag field.
This approach of separating the identification information is more Also there will be an identity data dependent on the same set of
costly than providing identification in each metrics block if only a identity information. If the set of identity information is formed
single metrics block is sent in an RTCP packet, but becomes as an independent block, then the dependence of an instance of a
beneficial as soon as more than one metrics block shares common identity block on identity data can be established by the identity
identification. block's having the tag field to indicate the relationship between
identity blocks and a specific application. An example use case is
for an endpoint may convey a call identifier or a global call
identifier associated with identity information. A flow measurement
tool that is not call-aware can then forward the metric reports along
with this correlation tag to network management. Network management
can then use this tag to correlate this report with other diagnostic
information such as call detail records.
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] (work in progress) is a block to convey information The example [PDV] (work in progress) is a block to convey information
about packet delay variation (PDV) only, consistent with the about packet delay variation (PDV) only, consistent with the
principle that a metrics block should address only one parameter of principle that a metrics block should address only one parameter of
interest. One simple metric of PDV is available in the RTCP RR interest. One simple metric of PDV is available in the RTCP RR
packet as the "jit" field. There are other PDV metrics which may be packet as the "jit" field. There are other PDV metrics which may be
more useful to certain applications. Two such metrics are the IPDV more useful to certain applications. Two such metrics are the IPDV
metric ([Y1540], [RFC3393]) and the MAPDV2 metric [G1020]. Use of metric ([Y1540], [RFC3393]) and the MAPDV2 metric [G1020]. Use of
these metrics is consistent with the principle in Section 5 of these metrics is consistent with the principle in Section 5 of
[RFC5968] that metrics should usually be defined elsewhere, so that [RFC5968] that metrics should usually be defined elsewhere, so that
RTCP standards define only the transport of the metric rather than RTCP standards define only the transport of the metric rather than
its nature. The purpose of this section is to illustrate the its nature. The purpose of this section is to illustrate the
architecure using the example of [PDV] (work in progress) rather than architecture using the example of [PDV] (work in progress) rather
to document the design of the PDV metrics block or to provide a than to document the design of the PDV metrics block or to provide a
tutorial on PDV in general. 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
skipping to change at page 16, line 13 skipping to change at page 14, line 13
discussed further in [PDV] (work in progress). discussed further in [PDV] (work in progress).
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 [RFC3550]. The second category mixers and RTP translators defined in [RFC3550]. For purposes of
relates to deployed system models used in many H.323 [H323] video reporting connection quality to other RTP systems, RTP mixers and RTP
conferences. The topologies in this category are Topo-Video-Switch- end systems are very similar. Mixers resynchronize audio packets and
MCU and Topo-RTCP-terminating-MCU. Such topologies based on systems do not relay RTCP reports received from one cloud towards other
do not behave according to [RFC3550]. As for the first category, the cloud(s). Translators do not resynchronize packets and SHOULD
forward certain RTCP reports between clouds. In this category, the
RTP system (end system, mixer or translator) which originates, RTP system (end system, mixer or translator) which originates,
terminates or forwards RTCP XR blocks is expected to handle RTCP, terminates or forwards RTCP XR blocks is expected to handle RTCP,
including RTCP XR, according to [RFC3550]. Provided this expectation including RTCP XR, according to [RFC3550]. Provided this expectation
is met, an RTP system using RTCP XR is architecturally no different is met, an RTP system using RTCP XR is architecturally no different
from an RTP system of the same class (end system, mixer, or from an RTP system of the same class (end system, mixer, or
translator) which does not use RTCP XR. Considering the translator translator) which does not use RTCP XR. The second category relates
and MCU are two typical topologies in thetwo categories mentioned to deployed system models used in many H.323 [H323] video
above, this document will take them as two typical examples to conferences. The topologies in this category are Topo-Video-Switch-
explain how RTCP XR report works in different RFC5117 topologies. MCU and Topo-RTCP-terminating-MCU. Such topologies based on systems
do not behave according to [RFC3550].
7.1. Applicability to MCU 7.1. Applicability to MCU
Topo-Video-Switch-MCU and Topo-RTCP-terminating-MCU, suffer from the Topo-Video-Switch-MCU and Topo-RTCP-terminating-MCU, suffer from the
difficulties described in [RFC5117]. These difficulties apply to difficulties described in [RFC5117]. These difficulties apply to
systems sending, and expecting to receive, RTCP XR blocks as much as systems sending, and expecting to receive, RTCP XR blocks as much as
to systems using other RTCP packet types. For example, a participant to systems using other RTCP packet types. For example, a participant
RTP end system may send media to a video switch MCU. If the media RTP end system may send media to a video switch MCU. If the media
stream is not selected for forwarding by the switch, neither RTCP RR stream is not selected for forwarding by the switch, neither RTCP RR
packets nor RTCP XR blocks referring to the end system's generated packets nor RTCP XR blocks referring to the end system's generated
skipping to change at page 17, line 23 skipping to change at page 15, line 25
For bidirectional unicast, an RTP system may usually detect RTCP XR For bidirectional unicast, an RTP system may usually detect RTCP XR
from a translator by noting that the sending SSRC is not present in from a translator by noting that the sending SSRC is not present in
any RTP media packet. However even for bidirectional unicast there any RTP media packet. However even for bidirectional unicast there
is a possibility of a source sending RTCP XR before it has sent any is a possibility of a source sending RTCP XR before it has sent any
RTP media (leading to transient mis-categorisation of an RTP end RTP media (leading to transient mis-categorisation of an RTP end
system or RTP mixer as a translator), and for multicast sessions - or system or RTP mixer as a translator), and for multicast sessions - or
unidirectional/streaming unicast - there is a possibility of a unidirectional/streaming unicast - there is a possibility of a
receive-only end system being permanently mis-categorised as a receive-only end system being permanently mis-categorised as a
translator sending XR report, i.e.,monitor collocated with translator sending XR report, i.e.,monitor collocated with
transaltor. Hence it is desirable for a translator that send XR to transaltor. Hence it is desirable for a translator that sends XR to
have a way to declare itself explicitly. have a way to declare itself explicitly.
8. IANA Considerations 8. IANA Considerations
None. None.
9. Security Considerations 9. Security Considerations
This document itself contains no normative text and hence should not This document itself contains no normative text and hence should not
give rise to any new security considerations, to be confirmed. give rise to any new security considerations, to be confirmed.
10. Acknowledgement 10. Acknowledgement
Geoff Hunt and Philip Arden wrote the initial draft for this document The authors would also like to thank Colin Perkins, Graeme Gibbs,
and provided useful reviews. Many thanks to them. The authors would Debbie Greenstreet, Keith Drage,Dan Romascanu, Ali C. Begen, Roni
also like to thank Colin Perkins, Graeme Gibbs, Debbie Greenstreet, Even for their valuable comments and suggestions on the early version
Keith Drage,Dan Romascanu, Ali C. Begen, Roni Even for their valuable of this document.
comments and suggestions on the early version of this document.
11. Informative References 11. Informative References
[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.
skipping to change at page 22, line 5 skipping to change at page 20, line 5
AVPF)", RFC 4585, July 2006. AVPF)", RFC 4585, July 2006.
[RFC5117] Westerlund, M., "RTP Topologies", RFC 5117, January 2008. [RFC5117] Westerlund, M., "RTP Topologies", RFC 5117, January 2008.
[RFC5968] Ott, J. and C. Perkins, "Guidelines for Extending the RTP [RFC5968] Ott, J. and C. Perkins, "Guidelines for Extending the RTP
Control Protocol (RTCP)", RFC 5968, September 2010. Control Protocol (RTCP)", RFC 5968, September 2010.
[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. 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
The following are the major changes compared to The following are the major changes compared to
draft-hunt-avtcore-monarch-02: draft-hunt-avtcore-monarch-02:
o Move Geoff Hunt and Philip Arden to acknowledgement section. o Move Geoff Hunt and Philip Arden to acknowledgement section.
skipping to change at page 23, line 5 skipping to change at page 20, line 39
o Update figure 1 and related text in section 3 according to the o Update figure 1 and related text in section 3 according to the
monitor definition in RFC3550. monitor definition in RFC3550.
o Revise section 9 to address monitor declaration issue. o Revise section 9 to address monitor declaration issue.
o Merge the first two bullet in section 6. o Merge the first two bullet in section 6.
o Add one new bullet to discuss metric block association in section o Add one new bullet to discuss metric block association in section
6. 6.
Author's Address A.3. draft-ietf-avtcore-monarch-02
Qin Wu The following are the major changes compared to 01:
o Deleting first paragraph of Section 1.
o Deleting Section 3.1, since the interaction with the management
application is out of scope of this draft.
o Separeate identity information correlation from section 5.2 as new
section 5.3.
o Remove figure 2 and related text from section 5.2.
o Editorial changes in the section 4 and the first paragraph of
section 7.
Authors' Addresses
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
Geoff Hunt
Unaffiliated
Email: r.geoff.hunt@gmail.com
Philip Arden
BT
Orion 3/7 PP4
Adastral Park
Martlesham Heath
Ipswich, Suffolk IP5 3RE
United Kingdom
Phone: +44 1473 644192
Email: philip.arden@bt.com
 End of changes. 26 change blocks. 
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