Network Working Group H. Scholz
Internet-Draft VOIPFUTURE GmbH
Intended status: Informational July 9, 2012
Expires: January 10, 2013
RTP Stream Quality Information Export using IPFIX
draft-scholz-ipfix-rtp-audio-quality-00
Abstract
This draft defines a set of Information Elements and matching
Templates to convey RTP media stream quality information in IPFIX
packets. The Information Elements describe the RTP quality using the
R-factor and Mean Opinion score (MOS) for the entire duration of a
monitored stream or for a smaller time slice thereof.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1. Quality of Service (QoS) Monitoring . . . . . . . . . 3
1.1.2. Service Level Agreement (SLA) . . . . . . . . . . . . 3
1.1.3. Troubleshooting . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. MOS measurement . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. rtpMOSCAlg . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. rtpMOSClass1 . . . . . . . . . . . . . . . . . . . . . . . 5
3.3. rtpMOSClass2 . . . . . . . . . . . . . . . . . . . . . . . 5
3.4. rtpMOSClass3 . . . . . . . . . . . . . . . . . . . . . . . 5
3.5. rtpMOSClass4 . . . . . . . . . . . . . . . . . . . . . . . 6
3.6. rtpMOSClass5 . . . . . . . . . . . . . . . . . . . . . . . 6
3.7. rtpMinMOS . . . . . . . . . . . . . . . . . . . . . . . . 6
3.8. rtpAvgMOS . . . . . . . . . . . . . . . . . . . . . . . . 7
3.9. rtpMaxMOS . . . . . . . . . . . . . . . . . . . . . . . . 7
3.10. rtpMinRFactor . . . . . . . . . . . . . . . . . . . . . . 7
3.11. rtpAvgRFactor . . . . . . . . . . . . . . . . . . . . . . 7
3.12. rtpMaxRFactor . . . . . . . . . . . . . . . . . . . . . . 8
4. Recommended Templates . . . . . . . . . . . . . . . . . . . . 8
4.1. Entire stream . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Time slice . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
IPFIX [RFC5101] and [RFC5102] define a framework allowing to export
arbitrary data from so called IPFIX exporters. One type of IPFIX
exporter may be co-located with Session Initiation Protocol (SIP)
[RFC3261] based VoIP entities or passively observe SIP based VoIP
calls. The signaling messages can be exported using
[I-D.trammell-ipfix-sip-msg] and Real Time Protocol (RTP) [RFC3550]
media streams are covered in [I-D.akhter-ipfix-perfmon]. Media
quality is out of the scope of both these documents. This document
defines a set of additional IPFIX Information Elements (IEs) to
describe RTP audio stream quality.
1.1. Use Cases
RTP stream flow information contained in IPFIX flow records can be
used for various tasks such as Quality of Service (QoS) monitoring,
Service Level Agreement (SLA) validation and general troubleshooting
of VoIP networks.
1.1.1. Quality of Service (QoS) Monitoring
Aggregated to higher-level metrics the in-depth information provided
by the RTP (and optionally SIP) flow records allow service providers
to gauge the overall quality of their network in terms of the quality
of experience (QoE). On this level an individual call is less
important but the overall quality (e.g. amount of minutes meeting
certain quality standards) can be used to get a quick overview on the
network and service performance.
1.1.2. Service Level Agreement (SLA)
SLAs are typically used as part of contracts between two network
operators. The requirements on the reliability of the data may be
higher compared to QoS Monitoring as the failure to meet
contractually agreed quality standards often has a direct commercial
impact.
1.1.3. Troubleshooting
An active network component (SIP proxy, B2BUA, media server) may not
have the capabilities to store session related information for a long
time to facilitate troubleshooting capabilities (e.g. due to missing
hard-disk). Such a system or a group of systems may run the metering
process and export the data to a collector for processing or
troubleshooting purposes.
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2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. MOS measurement
A multitude of Mean Opinion Score (MOS) assessment algorithms have
been defined of which only one or few may be available to an IPFIX
Metering Process. The quality (i.e. accuracy) of these algorithms
varies and has to be noted when transporting MOS values.
An IPFIX Metering Process may use these Information Elements to
convey information on the duration of the stream in which the quality
fell into the respective category as well as the measurement
algorithm used to obtain the information.
3.1. rtpMOSCAlg
The values carried in this IE are taken from the "RTCP XR QoE metric
block - Calculation Algorithm" sub-registry of the "RTP Control
Protocol Extended Reports (RTCP XR) Block Type Registry" as defined
in [I-D.wu-xrblock-rtcp-xr-quality-monitoring].
Even when an algorithm other than G.107 is used the rtpMOSClassN
Information Elements use the R-Factor based classes as defined in the
G.107 documentation.
Description: The calculation algorithm (CAlg) used by the Metering
Process to calculate the MOS value.
0: undefined: The algorithm is not known/specified.
1: ITU-T P.564
2: G.107
3: G.107 / ETSI TS 101 329-5 Annex E
4: ITU-T P.NAMS
5: ITU-T P.NBAMS
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6: RTCP - Real Time Control Protocol (not fefined in registry!)
Data Type: unsigned8
Data Type Semantics: identifier
PEN (provisional): tbd
ElementId (provisional): tbd
The MOS values calculated are separated into MOS classes based on the
ITU-T G.107 classes.
3.2. rtpMOSClass1
Description: Number of seconds the monitored stream had a MOS
quality lower than 3.10
Data Type: float32
Data Type Semantics: deltaCounter
PEN (provisional): tbd
ElementId (provisional): tbd
3.3. rtpMOSClass2
Description: Number of seconds the monitored stream had a MOS
quality larger than or equal 3.10 and lower than 3.60
Data Type: float32
Data Type Semantics: deltaCounter
PEN (provisional): tbd
ElementId (provisional): tbd
3.4. rtpMOSClass3
Description: Number of seconds the monitored stream had a MOS
quality larger than or equal 3.60 and lower than 4.03
Data Type: float32
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Data Type Semantics: deltaCounter
PEN (provisional): tbd
ElementId (provisional): tbd
3.5. rtpMOSClass4
Description: Number of seconds the monitored stream had a MOS
quality larger than or equal 4.03 and lower than 4.34
Data Type: float32
Data Type Semantics: deltaCounter
PEN (provisional): tbd
ElementId (provisional): tbd
3.6. rtpMOSClass5
Description: Number of seconds the monitored stream had a MOS
quality larger than or equal 4.34
Data Type: float32
Data Type Semantics: deltaCounter
PEN (provisional): tbd
ElementId (provisional): tbd
3.7. rtpMinMOS
Description: Minimum MOS value measured in the monitoring interval.
Data Type: float32
Data Type Semantics: quantity
PEN (provisional): tbd
ElementId (provisional): tbd
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3.8. rtpAvgMOS
Description: Average MOS value measured in the monitoring interval.
Data Type: float32
Data Type Semantics: quantity
PEN (provisional): tbd
ElementId (provisional): tbd
3.9. rtpMaxMOS
Description: Maximum MOS value measured in the monitoring interval.
Data Type: float32
Data Type Semantics: quantity
PEN (provisional): tbd
ElementId (provisional): tbd
3.10. rtpMinRFactor
Description: Minimum R-Factor measured in the monitoring interval.
Data Type: float32
Data Type Semantics: quantity
PEN (provisional): tbd
ElementId (provisional): tbd
3.11. rtpAvgRFactor
Description: Average R-Factor measured in the monitoring interval.
Data Type: float32
Data Type Semantics: quantity
PEN (provisional): tbd
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ElementId (provisional): tbd
3.12. rtpMaxRFactor
Description: Maximum R-Factor measured in the monitoring interval.
Data Type: float32
Data Type Semantics: quantity
PEN (provisional): tbd
ElementId (provisional): tbd
4. Recommended Templates
The defined RTP stream IPFIX templates must support both IPv4 and
IPv6 transport. They need to carry either flow information regarding
the entire duration of an RTP stream or specific to a shorter
observation interval.
The template incorporates IEs from [I-D.akhter-ipfix-perfmon] to
describe the RTP stream.
In order to correlate the RTP quality information with signaling
information (e.g. subscriber IDs) a correlation ID may be added to
the template. Note that this ID has yet to be defined and is outside
the scope of this document.
4.1. Entire stream
tbd
4.2. Time slice
tbd, based on previous template. Split a single RTP stream in three
flow records as example including (empty) 'RTP stream ended' flow
record.
5. Examples
tbd
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6. Acknowledgements
tbd
7. IANA Considerations
tbd
8. Security Considerations
tbd
9. References
9.1. Normative References
[I-D.wu-xrblock-rtcp-xr-quality-monitoring]
Hunt, G., Clark, A., Wu, W., Schott, R., and G. Zorn,
"RTCP XR Blocks for QoE metric reporting",
draft-wu-xrblock-rtcp-xr-quality-monitoring-06 (work in
progress), December 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5101] Claise, B., "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", RFC 5101, January 2008.
[RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J.
Meyer, "Information Model for IP Flow Information Export",
RFC 5102, January 2008.
9.2. Informative References
[I-D.akhter-ipfix-perfmon]
Akhter, A., "Information Elements for Flow Performance
Measurement", draft-akhter-ipfix-perfmon-00 (work in
progress), October 2010.
[I-D.trammell-ipfix-sip-msg]
Claise, B., Trammell, B., Kaplan, H., and S. Niccolini,
"SIP Message Information Export using IPFIX",
draft-trammell-ipfix-sip-msg-02 (work in progress),
October 2011.
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[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
Author's Address
Hendrik Scholz
VOIPFUTURE GmbH
Wendenstrasse 4
Hamburg 20097
Germany
Phone: +49 40 688 900 100
Email: hscholz@voipfuture.com
URI: http://www.voipfuture.com/
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