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Versions: 00 01 02                                                      
Network Working Group                                         Y. Kikuchi
Internet-Draft                            Kochi University of Technology
Intended status: Informational                             S. Matsushima
Expires: May 15, 2008                             Softbank Telecom Corp.
                                                               K. Nagami
                                                      Intec Netcore Inc.
                                                                  S. Uda
                                             Japan Advanced Institute of
                                                  Science and Technology
                                                            Nov 12, 2007


        Quality Measurement Requirements for Tunneling Protocols
                draft-kikuchi-tunnel-measure-req-02.txt

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   Copyright (C) The IETF Trust (2007).








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Abstract

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


Table of Contents

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

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

   3.  Motivations  . . . . . . . . . . . . . . . . . . . . . . . . .  6

   4.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Active vs. Passive . . . . . . . . . . . . . . . . . . . .  7
     4.2.  Quality Evaluation . . . . . . . . . . . . . . . . . . . .  7
     4.3.  Getting Quality Information  . . . . . . . . . . . . . . .  8
     4.4.  Overhead Consideration . . . . . . . . . . . . . . . . . .  8
     4.5.  Header Information . . . . . . . . . . . . . . . . . . . .  8
       4.5.1.  Sequence Numbering . . . . . . . . . . . . . . . . . .  9
       4.5.2.  Time Stamping  . . . . . . . . . . . . . . . . . . . .  9

   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10

   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 11

   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 12

   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
   Intellectual Property and Copyright Statements . . . . . . . . . . 14















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1.  Introduction

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

   In this document, ``tunnel'' refers to the various technologies used
   to provide networks or datalinks virtually over real networks.
   Examples of tunneling are GRE [2], IP Encapsulation within IP (IPIP)
   [3], and Pseudo Wire Emulation Edge-to-Edge (PWE3) [4].

   Measuring end-to-end quality of tunnels is necessary for Transport
   Service Providers (TSPs) who provide transport to users using
   tunnels.  However, the standards do not define the measurement and
   monitoring of a network, which is helpful when TSPs want to know the
   quality of their traffic through tunnels.  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 [1].




























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2.  Service Model

   Figure 1 shows that TSP X provides a transport between user A and
   user B using a tunnel.  The users construct an application over the
   transport.  The TSP may apply two or more tunnels to provide one
   transport.

   USER A                                                USER B
      |  \                                              /   |
      |   \--SLA A                              SLA B--/    |
      |           \                            /            |
      + ................... Application ................... +
      |              \                       /              |
      |               -------------         /               |
      |                            \       /                |
      |                             \     /                 |
    LAN A ............. Transport by TSP X  ............. LAN B
           |                                           |
           *-- 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: A Service Model of TSP

   TSPs provide a reachability of IP datagrams or layer 2 frames to
   users.  Typically, users are not able to identify the path details
   under the transport, which is the sequence of transit ISPs, because
   the tunnel eliminates the path information so that the users must
   recognize that both ends of the transport as a neighbor.

   TSPs provide simplified and virtual transports by hiding the
   underlying layers from the users.  The users are able to reduce the
   cost of operation and management because they need not maintain the
   underlying layers.  The reachability maintenance and the quality
   management are served as TSPs' communication services.

   There must be a Service Level Agreement (SLA) in the contract between
   a TSP and its user.  The SLA specifies the level that the TSP must
   maintain, which is a set of measurable characteristics such as the
   total unavailable time in a month, maximum out-of-sequence rates and
   some qualities for real time applications.

   In addition, TSPs may be able to provide better transports when the
   TSPs have several tunnels via different paths.  Furthermore, TSPs may
   be able to provide protocols needed by the users even if there are no



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   such protocols served by the ISPs.


















































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3.  Motivations

   TSPs need to know the quality of their tunnels in order to know
   whether the tunnels are 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 TSP itself, or the ISPs.

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

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
































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4.  Requirements

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

   The quality should be measured for tunnel traffic in operation
   because the measured quality is used to maintain the tunnel, to
   report regarding to the SLA and to select the best tunnel.  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 a tunnel, one is active
   and the other is passive.  Active measurement uses additional probing
   packets to determine the quality of the channel.  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' packets, the measurement
   should be determined passively rather than actively.

   On the other hand, it is not necessary to let the protocol have a
   quality measurement function with active measurement.  TSPs can
   construct the active measurement method independently from the target
   protocol.  A typical example is PING, which uses Internet Control
   Message Protocol (ICMP) [5].

4.2.  Quality Evaluation

   The standard that define a passive measurement of a tunneling
   protocol must contain two items, 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 tunnel
   are in-sequence or out-of-sequence.  Measurements of out-of-sequence
   packets are also basic metrics, such as loss, duplication and
   reordering.  Additionally, it may support to measure delay and/or
   jitter when the packets are in-sequence.

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

   Note that the tunnel quality discussed in this document shall not
   refer any specific application, so that the metrics must be



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   independent from the payload information.  See also the discussion in
   the Section 4.5.

4.3.  Getting Quality Information

   Tunneling protocols must support monitoring when the protocols have
   quality measurement functions.  The protocol must define how to
   monitor the result of the quality measurement of tunnels, such as
   SNMP [6].

   The parameters used in the measurement mechanisms might be modified
   by TSPs' operators.  Moreover, it may notify exceptional situations
   and illegal operations to the operators.

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.

   The types of overheads are as follows.

   o  the space of additional information in protocol header,

   o  the time of sending and receiving the information above, and

   o  the computing resources for quality measurement implemented in
      routers.

   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.

4.5.  Header Information

   The target tunneling protocol must provide information to measure the
   quality.  This means that the protocol header has enough information
   because the measurement must be passive and must not refer to the
   payload, according to the Section 4.1 and the Section 4.2.

   For example, in an extreme case, IPIP [3] does not have any extra
   field in the outer header on encapsulation, so that it is difficult
   to define passive metrics for IPIP.  However many tunneling protocols



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   have some information in their headers, which allows to detect some
   quality passively.

4.5.1.  Sequence Numbering

   If a protocol has a sequence number field, it is easy for egress
   router to determine the tunnel is in-sequence or not.  Moreover, it
   can recognize how the irregular is, such as loss, duplication and
   reordering.

   The original GRE [2] does not have much information but the extended
   GRE [7] has a sequence number field, therefore it can detect out-of-
   sequence and how irregular.

4.5.2.  Time Stamping

   If there is a timestamp in the header of a tunneling protocol, even
   the timestamps might be synchronized to a reference clock, it can
   measure delay and jitter.  Such kinds of metrics provide the tunnel
   quality when the packets are in-sequence rather than out-of-sequence.































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5.  Security Considerations

   Fraud header information, such as sequence numbers and time stamps,
   causes the measurement process to become disorganized.  This
   discussion boils down to the issues of the header protection.














































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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

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

6.2.  Informative References

   [2]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. Traina,
        "Generic Routing Encapsulation (GRE)", RFC 2784, March 2000.

   [3]  Perkins, C., "IP Encapsulation within IP", RFC 2003,
        October 1996.

   [4]  Bryant, S. and P. Pate, "Pseudo Wire Emulation Edge-to-Edge
        (PWE3) Architecture", RFC 3985, March 2005.

   [5]  Postel, J., "Internet Control Message Protocol", STD 5, RFC 792,
        September 1981.

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

   [7]  Dommety, G., "Key and Sequence Number Extensions to GRE",
        RFC 2890, September 2000.
























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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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