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Versions: 00                                                            
Network Working Group                                         Y. Kikuchi
Internet-Draft                            Kochi University of Technology
Intended status: Informational                             S. Matsushima
Expires: January 9, 2009                          Softbank Telecom Corp.
                                                               K. Nagami
                                                      Intec Netcore Inc.
                                                                  S. Uda
                                             Japan Advanced Institute of
                                                  Science and Technology
                                                            Jul 08, 2008


   Requirements of One-way Passive Measurement for End-to-End Quality
               draft-kikuchi-passive-measure-reqs-00.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
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Abstract

   This draft describes the necessary requirements to passively measure
   end-to-end quality and to monitor them via applicable ways.  This
   feature is crucial for Service Providers (SPs), especially who
   provide transports with Service Level Agreements (SLAs).


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements notation  . . . . . . . . . . . . . . . . . .  3

   2.  Service Model  . . . . . . . . . . . . . . . . . . . . . . . .  4

   3.  Motivations  . . . . . . . . . . . . . . . . . . . . . . . . .  5

   4.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  Active vs. Passive . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Quality Evaluation . . . . . . . . . . . . . . . . . . . .  6
     4.3.  Getting Quality Information  . . . . . . . . . . . . . . .  6
     4.4.  Overhead Consideration . . . . . . . . . . . . . . . . . .  7

   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8

   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . .  9

   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 10

   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
   Intellectual Property and Copyright Statements . . . . . . . . . . 12


















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1.  Introduction

   This draft describes the necessary requirements to passively measure
   end-to-end quality and to monitor them via applicable ways.

   Measuring end-to-end quality in passive ways is necessary for Service
   Providers (SPs) who provide transport to users.  However, the
   standards do not define the measurement and monitoring of a network,
   which is helpful when the SPs want to know the quality of their end-
   to-end traffic.  Therefore, measurement and monitoring standards need
   to be defined.

1.1.  Requirements notation

   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 [RFC2119].


































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2.  Service Model

   Figure 1 shows that SP X and SP Y provide a transport between user A
   and user B using some ISPs.  Let SP X and SP Y "Transport Service
   Providers" (TSPs) here because they should be distinguished from the
   intermediate ISPs.  The users construct an application over the
   transport.  The TSPs may apply two or more routes to provide one
   transport.

   USER A ................. Application ................ USER B
      |                                                     |
    (SLA)                                                 (SLA)
      |                                                     |
    TSP X >>................ Transport ................>> TSP Y
           |                                           |
           *-> ISP 1_1 -> ISP 1_2 -> ... -> ISP 1_n1 ->*
           |                                           |
           *-> ISP 2_1 -> ISP 2_2 -> ... -> ISP 2_n2 ->*
           :                                           :
           *-> ISP m_1 -> ISP m_2 -> ... -> ISP m_nm ->*


                          Figure 1: Service Model

   The TSPs maintain reachability and some required quality of the
   transport of IP datagrams to users.  There must be Service Level
   Agreements (SLAs) in the contract between the TSPs and thier users.
   The SLAs specify the level that the TSPs must maintain, which are
   sets of measurable characteristics such as total unavailable time in
   a month, loss of packets and some qualities for real time
   applications.




















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3.  Motivations

   TSPs need to know the quality of their traffic in order to know
   whether the traffic in a normal state or not.  The measured quality
   could be important information to trace down the cause of the trouble
   when an application is not working properly.  Without the necessary
   information, it is difficult for TSPs to determine whether problems
   come from the user, the TSPs, or the intermediate ISPs.

   The quality measurement is specially required by TSPs when they have
   SLAs to their customers.  They must be aware of the status of
   underlying traffic well and must report it as an evidence of quality
   to the users.

   TSPs also need to know the quality of a transport when they have
   multiple paths to serve the transport.  TSPs may be able to serve an
   appropriate transport to users by selecting a better quality path.
   In addition, the TSPs may be able to distribute the load of a
   transport to different paths.
































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4.  Requirements

   This section describes each requirement necessary to measure one-way
   end-to-end quality for TSPs.

   The quality should be measured for transports in operation because
   the measured quality is used to maintain the transports to report
   regarding to the SLA and to select the best path.  The measurement
   would be used not only for testing and benchmarking but also for the
   daily operational tool.  Therefore, the requirements are from
   operational points of view.

4.1.  Active vs. Passive

   There are two ways to measure the quality of transports, one is
   active and the other is passive.  Active measurement uses additional
   probing packets to determine the quality of the tranports.  Passive
   measurement uses the traffic packets to measure quality.

   From the TSPs point of view, passive measurement should be supported.
   Because SLAs should refer to the users' transports, the measurement
   should be determined passively rather than actively.

4.2.  Quality Evaluation

   The standard that define a passive measurement of transports must
   contain two elements, one is `WHAT' type of quality the protocol
   measure, or `metrics', and the other is `HOW' the protocol evaluate
   the quality.

   The most basic metric is to detect whether the packets in a transport
   are in-sequence or out-of-sequence.  Measurement of types of out-of-
   sequence packets are also basic metrics, such as lost, duplication
   and reordering in a transport.

   It is required to disable the measurement function for avoiding the
   measurement overhead in case when TSPs need not to measure the
   quality.  See also the discussion in the Section 4.4.

4.3.  Getting Quality Information

   The measurement mechanisms must define how to monitor the result of
   the quality of transports, such as SNMP [RFC3411].  The parameters
   used in the measurement mechanisms might be modified by TSPs'
   operators.  Moreover, they may notify exceptional situations and
   illegal operations to the operators.





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4.4.  Overhead Consideration

   Protocol designers should take into account the computing and space
   costs of the implementations where the standard defines the
   measurement and monitoring.  This includes overhead of traffic
   transmission, which may reflect the cost of equipment introductions
   and operational expenses.  The designers should not adopt non-
   scalable mechanisms and should pay particular attention to resource
   consumption sensitive protocols such as mobile protocols.

   We should adopt a simplified determination in some cases when both a
   precise complex determination and a simpler one exist.  Sometimes it
   is sufficient for operators to show an approximate degree different
   from the normal operation rather than a precise state.





































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5.  Security Considerations

   Not yet.
















































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Appendix A.  Acknowledgements

   The authors would like to thank for helpful discussions in TEReCo 2.0
   research project sponsored in part by the ministry of internal
   affairs and communications Japan (SCOPE 072309007).














































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6.  References

6.1.  Normative References

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

6.2.  Informative References

   [RFC3411]  Harrington, D., Presuhn, R., and B. Wijnen, "An
              Architecture for Describing Simple Network Management
              Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
              December 2002.






































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Authors' Addresses

   Yutaka Kikuchi
   Kochi University of Technology
   306B Research Collaboration Center
   185 Miyanokuchi, Tosayamada-cho
   Kami-shi, Kochi  782-0003
   JP

   Phone: +81-887-57-2068
   Email: yu@kikuken.org


   Satoru Matsushima
   Softbank Telecom Corp.
   1-9-1 Higashi-Shinbashi
   Minato-ku, Tokyo
   JP

   Email: satoru@ft.solteria.net


   Ken-ichi Nagami
   Intec Netcore Inc.
   1-3-3 Shin-suna
   Koto-ku, Tokyo
   JP

   Phone: +81-3-5565-5069
   Email: nagami@inetcore.com


   Satoshi Uda
   Japan Advanced Institute of Science and Technology
   1-1 Asahi-dai
   Nomi-shi, Ishikawa-ken  923-1292
   JP

   Email: zin@jaist.ac.jp












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