Re: [IPFIX] review of draft-scholz-ipfix-rtp-audio-quality-00

Michael Krüger <michael.krueger@voipfuture.com> Mon, 06 August 2012 11:06 UTC

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Cc: hscholz@voipfuture.com, IETF IPFIX Working Group <ipfix@ietf.org>
Subject: Re: [IPFIX] review of draft-scholz-ipfix-rtp-audio-quality-00
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Hi Hendrik,

Am 03.08.12 18:15, schrieb Paul Aitken:
> Hendrik,
> 
> 
>>
>> 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
> 
> Remove "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
>>
>>     This Internet-Draft is submitted in full conformance with the
>>     provisions of BCP 78 and BCP 79.
>>
>>     Internet-Drafts are working documents of the Internet Engineering
>>     Task Force (IETF).  Note that other groups may also distribute
>>     working documents as Internet-Drafts.  The list of current Internet-
>>     Drafts is at http://datatracker.ietf.org/drafts/current/.
>>
>>     Internet-Drafts are draft documents valid for a maximum of six months
>>     and may be updated, replaced, or obsoleted by other documents at any
>>     time.  It is inappropriate to use Internet-Drafts as reference
>>     material or to cite them other than as "work in progress."
>>
>>     This Internet-Draft will expire on January 10, 2013.
>>
>> Copyright Notice
>>
>>     Copyright (c) 2012 IETF Trust and the persons identified as the
>>     document authors.  All rights reserved.
>>
>>     This document is subject to BCP 78 and the IETF Trust's Legal
>>     Provisions Relating to IETF Documents
>>     (http://trustee.ietf.org/license-info) in effect on the date of
>>     publication of this document.  Please review these documents
>>     carefully, as they describe your rights and restrictions with respect
>>     to this document.  Code Components extracted from this document must
>>     include Simplified BSD License text as described in Section 4.e of
>>     the Trust Legal Provisions and are provided without warranty as
>>     described in the Simplified BSD License.
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 1]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>>     This document may contain material from IETF Documents or IETF
>>     Contributions published or made publicly available before November
>>     10, 2008.  The person(s) controlling the copyright in some of this
>>     material may not have granted the IETF Trust the right to allow
>>     modifications of such material outside the IETF Standards Process.
>>     Without obtaining an adequate license from the person(s) controlling
>>     the copyright in such materials, this document may not be modified
>>     outside the IETF Standards Process, and derivative works of it may
>>     not be created outside the IETF Standards Process, except to format
>>     it for publication as an RFC or to translate it into languages other
>>     than English.
>>
>>
>> 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
>>
>>
>>
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 2]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>> 1.  Introduction
>>
>>     IPFIX [RFC5101] and [RFC5102] define a framework allowing to export
> 
> NB these references will need to be updated to -bis.
> 
> "the export of arbitrary data".
> 
> 
>>     arbitrary data from so called IPFIX exporters.  One type of IPFIX
> 
> Why "so called"? They *are* IPFIX exporters!
> 
> 
>>     exporter may be co-located with Session Initiation Protocol (SIP)
> 
> At least, the IPFIX Device's Metering Process is co-located with the SIP
> devices / calls. The Exporting Process may be remote; you don't care.
> 
> 
>>     [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
> 
> say "run a Metering Process and export IPFIX to a Collecting Process for
> ...", since MP and CP are 5101 terms.
> 
> 
>>     troubleshooting purposes.
> 
> You might want to have a terminology section here, if only to refer
> readers to 5101. See how the other IPFIX drafts do this.
> 
> 
>>
>>
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 3]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>> 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
> 
> Technically it's not an "IPFIX Metering Process" - it's a SIP Metering
> Process connected to an IPFIX Exporting Process.
> For simplicity, just say "available to the Metering Process".
> 
> 
>>     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
>>
>>
>>
>>
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 4]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>>        6: RTCP - Real Time Control Protocol (not fefined in registry!)
> 
> Typo: "defined".
> 
> 
>>
>>     Data Type:  unsigned8
>>
>>     Data Type Semantics:  identifier
>>
>>     PEN (provisional):  tbd
> 
> Don't specify PEN numbers.
> 
> 
>>
>>     ElementId (provisional):  tbd
> 
> You might want to number these, eg TBD1, TBD2, ...
> 
> 
>>
>>     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
> 
> It's unusual to represent time as a float in IPFIX. Could you pick a
> suitable resolution (eg, milliseconds or microseconds) and export an
> integer?
> 
The purpose of these IE items is to report the amount of full seconds
VoIP streams have been in either one of these 5 MOS classes. So I
suggest to change the type to unsigned64.

Regards,
Michael

> 
>>
>>     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
>>
>>
>>
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 5]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>>     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
>>
>>
>>
>>
>>
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 6]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>> 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
>>
>>
>>
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 7]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>>     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.
> 
> Lots of TBD's from here on...
> 
> P.
> 
>> 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
>>
>>
>>
>>
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 8]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>> 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.
>>
>>
>>
>> Scholz                  Expires January 10, 2013                [Page 9]
>> 
>> Internet-Draft            RTP Streams in IPFIX                 July 2012
>>
>>
>>     [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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>> Scholz                  Expires January 10, 2013               [Page 10]
>> 
>