Internet DRAFT - draft-zheng-ippm-passive-gap-analysis

draft-zheng-ippm-passive-gap-analysis







Network Working Group                                           L. Zheng
Internet-Draft                                                 S. Aldrin
Intended status: Informational                       Huawei Technologies
Expires: April 21, 2014                                 October 18, 2013


               Gap Analysis of IPPM Passive Measurements
              draft-zheng-ippm-passive-gap-analysis-00.txt

Abstract

   This document performs a gap analysis of the current state of IPPM WG
   and ongoing work, in terms of passive measurements, according to the
   new charter of the IPPM WG.

Requirements Language

   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].

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
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   This Internet-Draft will expire on April 21, 2014.

Copyright Notice

   Copyright (c) 2013 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
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   to this document.  Code Components extracted from this document must
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Passive Measurements VS Active Measurements . . . . . . . . .   2
   3.  Gap Analysis for Passive Measurements . . . . . . . . . . . .   3
     3.1.  Framework for IP Performance Metrics  . . . . . . . . . .   3
     3.2.  IP Performance Metrics  . . . . . . . . . . . . . . . . .   4
     3.3.  Registry  . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Future Work for Passive Measurement . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   The IPPM working group has been recently re-chartered.  According to
   the new charter, passive measurement and hybrid measurement methods
   are now included.  This document performs a gap analysis of the
   current status of work in the IPPM WG in terms of passive
   measurements.  Section 2 of the document gives a brief introduction
   of passive measurement.  Section 3 summarizes the current status of
   the IPPM, and gives an analysis on what is missing or was not
   considered, for passive measurements, in terms of framework of
   metrics, measurement of metrics, registry, etc.  Section 4 lists the
   future work required for passive measurements based on the gap
   analysis.  The analysis for hybrid measurements is out of the scope
   of this document.

2.  Passive Measurements VS Active Measurements

   Passive and active measurements are two common approaches for
   monitoring the network.  The passive approach measures real traffic
   and does not increase the traffic on the network for the
   measurements.  This makes it attractive for in-service monitoring,
   network trouble-shooting and fault location.  Since the passive
   approach may require viewing packets on the network, there can be
   privacy or security issues.  The active approach relies on the
   capability to inject test packets into the network, but as such it
   creates extra traffic.  The benefit of active measurements is that



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   they can be run from virtually anywhere in the network.  One
   difficulty, though, is that the discrete nature of active probing
   limits the resolution of the measurements.  There is also evidence of
   limitations of probe-based packet loss measurement in low-loss
   environments.  Both passive and active measurements have their
   strengths and should be regarded as complementary.

3.  Gap Analysis for Passive Measurements

   This section gives an analysis on what is missing for passive
   measurements in relation to IPPM, in terms of framework of metrics,
   measurement of metrics and registry.

3.1.  Framework for IP Performance Metrics

   The IETF IP Performance Metrics (IPPM) working group first created a
   framework for metric development in [RFC2330], which enabled
   development of many fundamental metrics.  [RFC2330] has been updated
   once by [RFC5835], which describes a detailed framework for composing
   and aggregating metrics originally defined in [RFC2330].

   The ongoing work [I-D.ietf-ippm-2330-update] proposes to update the
   IPPM Framework with advanced considerations for measurement
   methodology and testing.  It describes new stream parameters for both
   network characterization and support of application design using IPPM
   metrics.  All the previous work done for IP performance metrics
   framework and the ongoing update for the framework has the
   assumption, which is not explicitly stated, that the measurement
   method of the metrics is active measurement.

   The result of this is, while many of the current framework aspects
   are still applicable to passive measurement, some of them are not
   applicable.  In one example, section 11 of [RFC2330] introduces a
   separation between three distinct notions: singletons, samples, and
   statistics, which are not applicable to passive measurements, since
   the test packet is not required for passive measurements, nor is the
   sampling.














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   But there are certainly equivalent concepts in passive measurements.
   For example, consider using TCP traffic to determine the two-way
   delay between two hosts.  A singleton would be the timing of a single
   sequence number - acknowledgement pairing, a sample would be a
   collection of these, and the statistical metric would take the
   minimum, over a short time interval (in order to reduce or eliminate
   think-time and delayed-ACK effects).  In another example, the concept
   of a packet of type "P", while still applicable in principle, will
   have to be specified differently.  An updated or new passive
   framework document is needed, while equivalent concepts need to be
   carried over as much as possible with passive-friendly definitions.

3.2.  IP Performance Metrics

   The IPPM WG has defined more than 30 metrics, the most recently
   published document that defines metrics is [RFC6049].  The commonly
   used metrics include IPPM Metrics for Measuring Connectivity
   [RFC2678], One-way Delay Metrics[RFC2679], One-way Packet Loss
   Metrics [RFC2680], Round-trip Delay Metrics [RFC2681], One-way Loss
   Pattern Sample Metrics[RFC3357], IP Packet Delay Variation Metric
   [RFC3393], IPPM Metrics for periodic streams [RFC3432] etc.

   All the existing metrics defined follow the framework for IP
   performance metrics [RFC2330] , which has the implicit assumption
   that the measurement method of the metrics is active measurement.
   Passive methodologies for existing [RFC2330] based active metrics
   need to be defined, which would require loosening some of the
   constraints as well as changes to the guidelines.  For example, the
   measurement methodologies for One-way Delay Metrics [RFC2679] and
   One-way Packet Loss Metrics [RFC2680] call for, amongst other things,
   selection of the Src and Dst addresses at the Src host.  This will be
   difficult to achieve for passive measurement.

   Careful examination and thorough analysis needs to be made, in order
   to decide, which aspects of current metrics need to be redefined for
   passive measurements, and which aspects could be reused by passive
   measurements as is.

3.3.  Registry

   [RFC4148] defines an initial registry of the metrics defined in the
   IPPM WG and the rules to manage the registry.  However, [RFC4148] was
   obsoleted by [RFC6248] because it was "not believed to be feasible or
   even useful to register every possible combination of Type P, metric
   parameters, and Stream parameters using the current structure of the
   IPPM Metrics Registry".  This led to the [RFC4148] registry having
   "very few users, if any".




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   The ongoing work [I-D.bagnulo-ippm-new-registry-independent] and
   [I-D.bagnulo-ippm-new-registry] creates, a registry for commonly used
   metrics, defines the rules for assignments in the new registry and
   performs initial allocations, respectively.
   [I-D.bagnulo-ippm-new-registry-independent] proposes one particular
   registry structure with independent registries for each of the fields
   involved, while [I-D.bagnulo-ippm-new-registry] explores an
   alternative structure with a single registry with multiple sub-
   registries.  The metrics for passive measurement should be taken into
   consideration for both registry structure designs.

4.  Future Work for Passive Measurement

   Based on the above gap analysis, it could be concluded that the
   following new work needs to be done in the IPPM working group:

   1.  Framework for metrics: An passive-friendly updated framework
   document is needed for passive measurement.

   2.  Metrics: Careful examination on currently defined metrics,
   particularly the measurement aspects, needs to be made by the working
   group.  Some metrics need to be updated for passive measurement, some
   metrics may be reused by passive measurements as is.  New metrics may
   also need to be defined for passive measurement.

   3.  Registry: The passive measurement should be taken into
   consideration for the ongoing registry structure design work.

5.  Security Considerations

   This document does not bring new security issue to IPPM.

6.  IANA Considerations

   This document makes no request to IANA.

7.  Acknowledgements

   The authors would like to thank Brain Trammell, Paul Coverdale for
   their valuable comments.

8.  References









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8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

8.2.  Informative References

   [I-D.bagnulo-ippm-new-registry-independent]
              Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and
              A. Morton, "A registry for commonly used metrics.
              Independent registries", draft-bagnulo-ippm-new-registry-
              independent-01 (work in progress), July 2013.

   [I-D.bagnulo-ippm-new-registry]
              Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and
              A. Morton, "A registry for commonly used metrics", draft-
              bagnulo-ippm-new-registry-01 (work in progress), July
              2013.

   [I-D.ietf-ippm-2330-update]
              Fabini, J. and A. Morton, "Advanced Stream and Sampling
              Framework for IPPM", draft-ietf-ippm-2330-update-01 (work
              in progress), October 2013.

   [RFC2330]  Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
              "Framework for IP Performance Metrics", RFC 2330, May
              1998.

   [RFC2678]  Mahdavi, J. and V. Paxson, "IPPM Metrics for Measuring
              Connectivity", RFC 2678, September 1999.

   [RFC2679]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Delay Metric for IPPM", RFC 2679, September 1999.

   [RFC2680]  Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
              Packet Loss Metric for IPPM", RFC 2680, September 1999.

   [RFC2681]  Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
              Delay Metric for IPPM", RFC 2681, September 1999.

   [RFC3357]  Koodli, R. and R. Ravikanth, "One-way Loss Pattern Sample
              Metrics", RFC 3357, August 2002.

   [RFC3393]  Demichelis, C. and P. Chimento, "IP Packet Delay Variation
              Metric for IP Performance Metrics (IPPM)", RFC 3393,
              November 2002.





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   [RFC3432]  Raisanen, V., Grotefeld, G., and A. Morton, "Network
              performance measurement with periodic streams", RFC 3432,
              November 2002.

   [RFC4148]  Stephan, E., "IP Performance Metrics (IPPM) Metrics
              Registry", BCP 108, RFC 4148, August 2005.

   [RFC5835]  Morton, A. and S. Van den Berghe, "Framework for Metric
              Composition", RFC 5835, April 2010.

   [RFC6049]  Morton, A. and E. Stephan, "Spatial Composition of
              Metrics", RFC 6049, January 2011.

   [RFC6248]  Morton, A., "RFC 4148 and the IP Performance Metrics
              (IPPM) Registry of Metrics Are Obsolete", RFC 6248, April
              2011.

Authors' Addresses

   Lianshu Zheng
   Huawei Technologies
   China

   Email: vero.zheng@huawei.com


   Sam K. Aldrin
   Huawei Technologies

   Email: aldrin.ietf@gmail.com





















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