Internet DRAFT - draft-clark-avt-rtcpxr-video
draft-clark-avt-rtcpxr-video
Internet Engineering Task Force A. Clark
Internet-Draft Telchemy Incorporated
Expires: 22nd December 2006 A. Pendleton
Nortel
June 2006
RTCP XR - IP Video Metrics Report Blocks
draft-clark-avt-rtcpxr-video-02
Status of this Memo
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This Internet-Draft will expire on 22nd December 2006.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines extensions to the RTCP XR extended report
packet type blocks to support video over IP (VoIP) monitoring
for IPTV and video conferencing endpoint reporting.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 2
3. IP Video Metrics Report Block . . . . . . . . . . . . . . . 4
4. IP Video Metrics Configuration Block . . . . . . . . . . . . 10
5. Practical applications . . . . . . . . . . . . . . . . . . 12
6. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 13
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
10. Informative References . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . .
Intellectual Property and Copyright Statements . . . . . . .
1. Introduction
This draft defines several new block types to augment those defined
in RFC3611 for use in Quality of Service reporting for video over IP.
The new block types defined in this draft are the IP Video Metrics
Report Block, and the IP Video Metrics Configuration Block.
2. Definitions
2.1 Local and Remote IP Endpoints
A report block produced per this draft is normally produced by the
endpoint of an RTP stream, and relates to the quality of the received
RTP stream and impairments that may affect the RTP payload. The
diagram below illustrates the potential end and mid points that may
be involved in this process. Within the context of this example,
endpoint "C" is the reporting endpoint and the RTCP XR report relates
to the RTP stream from "B" to "C". The other points "A", "B" and "D"
could also be generating RTCP XR reports.
-----------> --------RTP----------> ------------->
<A> <B> <C> <D>
<----------- <-------RTP----------- | <-------------
|
<------RTCP XR---------|
With respect to RTCP XR report blocks generated by "C" in relation to
the RTP stream from "B" to "C".
(i) The term "External" is used to relate to the network connected to
the other side of "this" endpoint (i.e. to the connection from "C" to
"D").
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(ii) The Local IP Endpoint is "this" endpoint (i.e. "C")
(iii) The Remote IP Endpoint is the source for the RTP stream
terminated at this endpoint, and for which packet/frame related
metrics apply. (i.e. "B")
(iv) The Remote External Endpoint is the remote endpoint on the
"external" side of this endpoint (i.e. "D").
(v) The endpoint on the external side of the Remote IP Endpoint (i.e.
"A") does not have a specific term applied to it, however note that
some metrics may apply to the "A" to "B" connection.
2.2 Cumulative and Interval Metrics
Cumulative metrics relate to the entire duration of the call to the
point at which metrics are determined and reported, and are typically
used to report call quality. Cumulative metrics generally result in
a lower volume of data that may need to be stored, as each report
supersedes earlier reports.
Interval metrics relate to the period since the last Interval report.
Interval data may be easier to correlate with specific network events
for which timing is known, and may also be used as a basis for
threshold crossing alerts.
Note that interval metrics for the start and end of calls may be
unreliable due to factors such as irregular interval length and the
difficulty in knowing when packet transmission started and ended.
2.3 Bursts and Gaps
The terms Burst and Gap are used in a manner consistent with that of
RTCP XR (RFC3611). A Gap is a period of time between Bursts such
that any lost or discarded packets or frames are separated by some
number of "good" packets or frames. A Burst is a period of time that
fails the test for a Gap, and hence corresponds to a degraded quality
period. The recommended value for Gmin in RFC3611 resulted in a
Burst being a period of time during which the packet loss/discard
rate exceeded 5%. As video is generally more sensitive to packet loss
this report block uses a larger value for Gmin.
2.4 Numeric formats
This report block makes use of binary fractions. The terminology
used is
S X:Y, where S indicates a signed representation,
X the number of bits prior to the decimal place and
Y the number of bits after the decimal place.
Hence 8:8 represents an unsigned number in the range 0.0039 to
255.996.
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3 Video Metrics Report Block
3.1 Block Description
This block comprises a header and a series of sub-blocks. The
Map field in the header defines which sub-blocks are present.
Header sub-block
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=N | Map | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP Layer Loss Metrics sub-block
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Pre-FEC Loss Rate | Post-FEC Loss Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of IP packets expected |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RTP Metrics sub-block
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Rate | Discard Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Average Jitter | Jitter Percentile |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Threshold | Burst Duration (ms) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Gap Duration (ms) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Burst Loss/Disc Proportion | Gap Loss/Disc Proportion |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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MPEG Transport Metrics sub-block
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Video Stream PID | Audio Stream PID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Loss Rate | Discard Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Average Jitter | Jitter Percentile |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Threshold | Burst Duration (ms) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Gap Duration (ms) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Burst Loss/Disc Percentage | Gap Loss/Disc Percentage |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Video/Audio Metrics sub-block
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Full Frame Loss Rate | Interpolated Frame Loss Rate |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VSTQ - Transmission Quality | VSPQ - Picture Quality |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VSAQ - Audio Quality | VSMQ - Multimedia Quality |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VSCQ - Control Quality | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Video bit rate (bits/sec) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Audio bit rate (bits/sec) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A-V Delay (Network I/F) | A-V Delay (Video I/F) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Round Trip Delay (media) | Round Trip Delay (control) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Playout Buffer Metrics sub-block
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Playout Interrupt Count | Mean Playout Interrupt Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Playout buffer size | Mean buffer level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2 Header
Implementations MUST send the Header block within each High
Resolution Metrics report.
3.2.1 Block type
Nine Video Performance Reporting Metrics blocks are defined
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mmm = Video Metrics- Cumulative, Locally Generated
mmm+1 = Video Metrics- Cumulative, Relayed from Remote IP Endpoint
mmm+2 = Video Metrics- Cumulative. Relayed from Remote External
Endpoint
mmm+3 = Video Metrics- Interval - Locally Generated
mmm+4 = Video Metrics- Interval - Relayed from Remote IP Endpoint
mmm+5 = Video Metrics- Interval - Relayed from Remote External
Endpoint
mmm+6 = Video Metrics- Alert - Locally Generated
mmm+7 = Video Metrics- Alert - Relayed from Remote IP Endpoint
mmm+8 = Video Metrics- Alert - Relayed from Remote External
Endpoint
The time interval associated with these report blocks is left to the
implementation. Spacing of RTCP reports should be in accordance
with RFC3550 however the specific timing of RTCP XR Video reports may
be determined in response to an internally derived alert such as a
threshold crossing.
3.2.2 Map field
An Map field indicates the optional sub-blocks present in this
report. A 1 indicates that the sub-block is present, and a 0 that
the block is absent. If present, the sub-blocks must be in the
sequence defined in this document.
The bits have the following definitions:
0 RTP Metrics block
1 MPEG Transport Metrics block
2-15 Reserved, set to 0
3.2.3 Block Length
The block length indicates the length of this report in 32 bit
words and includes the header and any extension octets.
3.2.5 Correlation tag
The correlation tag facilitates the correlation of this report
block with other call or session related data or endpoint data.
3.3 IP Layer loss metrics sub-block
The IP Layer loss metrics sub-block MUST be present.
3.3.1 Pre-FEC Loss Rate
The proportion of IP packets lost before the effects of FEC,
expressed as a binary fraction in 0:16 format.
3.3.2 Post-FEC Loss Rate
The effective proportion of IP packets after before the effects of
FEC, expressed as a binary fraction in 0:16 format.
3.3.3 Number of IP Packets Expected
The number of IP packets that the receiving system estimates that
it should have received.
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3.4 RTP Metrics sub-block
If RTP transport is used, the RTP Metrics sub-block MUST be present
and if present MUST be indicated in the Map field.
3.4.1 Source SSRC
The SSRC associated with the RTP stream to which this report block
relates.
3.4.2 Loss Rate
The (post-FEC) proportion of RTP frames lost in the network.
3.4.3 Discard Rate
The proportion of RTP frames discarded due to late or early
arrival.
3.4.4 Average Jitter
The average PPDV, MAPDV or Y.1540 jitter level in milliseconds
3.4.5 Jitter Percentile
The proportion of RTP frames arriving later than the jitter
threshold
3.4.6 Threshold
The Gmin threshold associated with the definition of bursts and
gaps.
3.4.7 Burst duration
The duration of bursts of lost and discarded RTP frames
expressed in milliseconds.
3.4.8 Gap duration
The mean duration of gaps between bursts expressed in milliseconds.
3.4.9 Burst loss/discard proportion
The proportion of frames lost or discarded during burst periods
expressed as a binary fraction.
3.4.10 Gap loss/discard proportion
The proportion of frames lost or discarded during burst periods
expressed as a binary fraction.
3.5 MPEG Transport Metrics sub-block
The MPEG Transport Metrics sub-block MUST be present if MPEG
Transport is used, and if present MUST be indicated in the Map
field.
3.5.1 Video Stream Program ID
The Program ID (PID) associated with the video stream.
3.5.2 Audio Stream Program ID
The Program ID (PID) associated with the audio stream
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3.5.3 Loss Rate
The (post-FEC) proportion of Transport Units lost in the network.
3.5.4 Discard Rate
The proportion of Transport Units discarded due to late or early
arrival.
3.5.5 Average Jitter
The average PPDV, MAPDV or Y.1540 jitter level in milliseconds
3.5.6 Jitter Percentile
The proportion of Transport Units arriving later than the jitter
threshold
3.5.7 Threshold
A threshold associated with the definition of bursts and gaps.
3.5.8 Burst duration
The duration of bursts of lost and discarded Transport Units
expressed in milliseconds.
3.5.9 Gap duration
The mean duration of gaps between bursts expressed in milliseconds.
3.5.10 Burst loss/discard proportion
The proportion of Transport Units lost or discarded during burst
periods expressed as a binary fraction.
3.5.11 Gap loss/discard proportion
The proportion of Transport Units lost or discarded during burst
periods expressed as a binary fraction.
3.6 Video/Audio Metrics sub-block
The Video/Audio Metrics sub-block MUST be present.
3.6.1 Full frame loss rate
The proportion of full or intra-frame encoded video frames lost
3.6.2 Interpolated frame loss rate
The proportion of interpolated video frames lost
3.6.3 VSTQ - Video Service Transmission Quality
The video service transmission quality expressed as a score in the
range 0.0 to 50.0. This is a codec independent measure of the
ability of the bearer channel to support reliable video.
3.6.4 VSPQ - Video Service Picture Quality
The video service picture quality expressed as a score in the range
0.0 to 50.0. This is a codec dependant measure that is related to
the subjective quality of the decoded video stream.
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3.6.5 VSAQ - Video Service Audio Quality
The video service audio quality expressed as a score in the range
0.0 to 50.0. This is an audio codec dependant measure that is
related to the subjective quality of the decoded audio stream(s).
3.6.6 VSMQ - Video Service Multimedia Quality
The video service multimedia quality expressed as a score in the
range 0.0 to 50.0. This is a composite audio/video measure that
is related to the overall subjective user experience and considers
picture quality, audio quality and audio/video synchronization.
3.6.7 VSCQ - Video Service Control Plane Quality
The video service control plane (trick play) quality expressed as
a score in the range 0.0 to 50.0. This is a measure that is related
to the performance of the video stream control channel.
3.6.8 Reserved
3.6.9 Video bit rate
The short term average bit rate of the video codec.
3.6.10 Audio bit rate
The short term average bit rate of the audio codec
3.6.11 Audio-Video Delay (Network Interface)
The relative delay between audio and video measured before the
decoder and expressed in milliseconds
3.6.12 Audio-Video Delay (Video Interface)
The relative delay between audio and video measured after the
decoder and expressed in milliseconds
3.6.13 Round Trip Delay (Media)
The round trip delay for the media path, required only for
interactive video sessions.
3.6.14 Round Trip Delay (Control)
The round trip delay for the video control (trick play) path.
3.7 Playout Buffer Metrics sub-block
The Playour Buffer Metrics sub-block MUST be present.
3.7.1 Playout Interruption Count
The number of interruptions in video playout that have occurred due
to playout buffer starvation or excessive packet loss.
3.7.2 Mean Playout Interruption Size
The mean size of interruptions in playout, expressed in multiples of
100 milliseconds
3.7.3 Playout Buffer Size
The playout buffer size, expressed in multiples of 100 milliseconds
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3.7.4 Mean Buffer Size
The average playout buffer size expressed in multiples of 100
milliseconds
4. RTCP XR Video Metrics Configuration Block
This block type provides a flexible means to describe the algorithms
used for call quality calculation and other data. This block need
only be exchanged occasionally, for example sent once at the start
of a call.
Header sub-block
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=N | Map | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Algorithm sub-block
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Alg type | Descriptor len| Algorithm descriptor... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... Algorithm descriptor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.1 Header
Implementations MUST send the Header block within each Video Metrics
Configuration report.
4.1.1 Block type
One Video Metrics Configuration block is defined
mmm+9 = Video Metric Configuration Block
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The time interval associated with these report blocks is left to the
implementation. Spacing of RTCP reports should be in accordance
with RFC3550 however the specific timing of RTCP XR Video reports may
be determined in response to an internally derived alert such as a
threshold crossing.
4.1.2 Map field
An Map field indicates the optional sub-blocks present in this
report. A 1 indicates that the sub-block is present, and a 0 that
the block is absent. If present, the sub-blocks must be in the
sequence defined in this document.
The bits have the following definitions:
0 Correlation Tag
1 Algorithm Descriptor 1
2 Algorithm Descriptor 2
3 Algorithm Descriptor 3
4 Algorithm Descriptor 4
5 Algorithm Descriptor 5
6 Algorithm Descriptor 6
7 Algorithm Descriptor 7
8 Algorithm Descriptor 8
9 Vendor Specific Extension
10-15 Reserved, set to 0
4.1.3 Block Length
The block length indicates the length of this report in 32 bit
words and includes the header and any extension octets.
4.1.4 SSRC
The SSRC of the stream to which this report relates.
4.2 Correlation Tag
The Correlation Tag sub-block MAY be present and if present
MUST be indicated in the map field. This tag facilitates the
correlation of the high resolution VoIP metrics report blocks
with other call-related data, session-related data or endpoint data.
An example use case is for an endpoint may convey its version of a
call identifier or a global call identifier via this tag. A
flow measurement tool (sniffer) that is not call-aware can then
forward the RTCP XR 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.
The Tag Type indicates the use of the correlation tag. The following
values are defined:
0: IMS Charging Identity (ICID) subfield of the
P-Charging-Vector header specified in RFC 3455.
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1: Globally unique ID as specified in ITU-T H.225.0
(Table 20/H.225.0).
2: Conference Identifier, per ITU-T H.225.0
(Table 20/H.225.0).
3: SIP Call-ID as defined in RFC 3261.
4: PacketCable Billing Call ID (BCID).
5: Text string using the US-ASCII character set.
6: Octet sting.
7-255: Future growth.
Although the intent of this RFC is to list all currently known
values of usable correlation tags, it is possible that new values
may be defined in the future. An IANA registry of correlation
tags is recommended.
The tag length indicates the overall length of the sub-block in
32 bit words and includes the tag type and length fields.
4.3 Algorithm description
The Algorithm Description sub-block MAY be present however if present
MUST be indicated in the MAP field
The Algorithm descriptor is a bit field which indicates which
algorithm is being described. The bits are defined as:-
Bit 0: MOS-LQ Algorithm
Bit 1: MOS-CQ Algorithm
Bit 2: R-LQ Algorithm
Bit 3: R-CQ Algorithm
Bit 4: Video Monitoring Algorithm
Bit 5: Audio Monitoring Algorithm
Bit 6: Transmission Quality Monitoring Algorithm
Bit 7: Reserved and set to 0
The descriptor length gives the overall length of the descriptor in
32 bit words and includes the algorithm descriptor and length fields.
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The algorithm descriptor is a text field that contains the
description or name of the algorithm. If the algorithm name is
shorter than the length of the field then the trailing octets
must be set to 0x00.
For example, an implementation may report:
Algorithm descriptor = 0x10 - Video estimation algorithm
Descriptor length = 3 - 3 words
Descriptor = "Alg X" 0x00 - description
5. Practical Applications
5.1 Overview
The objective of this section is to identify a number of cases in
which there could potentially be some ambiguity in the application
of the report blocks defined above or some exceptions to the
defined operation of the metrics.
6. Summary
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7. IANA Considerations
8. Security Considerations
RTCP reports can contain sensitive information since they can provide
information about the nature and duration of a session established
between two endpoints. As a result, any third party wishing to
obtain this information should be properly authenticated and the
information transferred securely.
9. Contributors
10. Informative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson,
"RTP: A Transport Protocol for Real-Time Applications", STD 64,
RFC 3550, July 2003.
[3] Friedman, T., Caceres, R. and A. Clark, "RTP Control Protocol
Extended Reports (RTCP XR)", RFC 3611, November 2003.
Authors' Addresses
Alan Clark
Telchemy Incorporated
2905 Premiere Parkway, Suite 280
Duluth, GA 30097
Email: alan@telchemy.com
Amy Pendleton
Nortel
2380 Performance Drive
Richardson, TX 75081
Email: aspen@nortel.com
Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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Intellectual Property
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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