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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 5472

 Internet Draft                                              Tanja Zseby
 Document: <draft-ietf-ipfix-as-04.txt>                     Elisa Boschi
 Expires: August 2005                                   Fraunhofer FOKUS
                                                          Nevil Brownlee
                                                                   CAIDA
                                                           Benoit Claise
                                                           Cisco Systems

                                                           February 2005


                           IPFIX Applicability
                        draft-ietf-ipfix-as-04.txt

    Status of this Memo

    This document is an Internet-Draft and is subject to all
    provisions of section 3 of RFC 3667. By submitting this
    Internet-Draft, each author represents that any applicable
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    will be disclosed, in accordance with RFC 3668.

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    Copyright Notice

    Copyright (C) The Internet Society (2005).










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    Abstract

    This document describes what type of applications can use the IP
    Flow Information Export (IPFIX) protocol and how they can use
    the information provided by IPFIX. It furthermore shows how the
    IPFIX framework relates to other architectures and frameworks.















































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 Table of Contents
    1.   Introduction.............................................3
    2.   Applications of IPFIX....................................4
    2.1  Accounting...............................................4
    2.1.1 Example.................................................5
    2.2  Security Analysis and Intrusion Detection with IPFIX.....6
    2.3  Network Planning.........................................7
    2.4  Peering Agreements.......................................7
    2.5  Traffic Engineering......................................7
    2.6  Data Warehousing and Mining..............................8
    2.7  SLA validation...........................................8
    2.8  Traffic Monitoring.......................................8
    2.8.1 Measurement of Round-trip-time (RTT)....................9
    2.8.2 Measurement of One-way-delay (OWD)......................9
    2.8.3 Measurement of One-way-loss (OWL)......................10
    2.8.4 Measurement of IP delay variation (IPDV)...............10
    3.   Relation of IPFIX to other frameworks and protocols.....10
    3.1  IPFIX and AAA...........................................10
    3.1.1 Connecting via an AAA Client...........................11
    3.1.2 Connecting via an Application Specific Module (ASM)....12
    3.2  IPFIX and RTFM..........................................13
    3.2.1 Flow Definition........................................13
    3.2.2 Configuration and Management...........................13
    3.2.3 Data Model Details.....................................14
    3.2.4 Application/Transport Protocol.........................14
    3.2.5 RTFM Summary...........................................15
    3.3  IPFIX and IPPM..........................................15
    3.4  IPFIX and PSAMP.........................................15
    3.5  IPFIX and RMON..........................................15
    3.6  IPFIX and IDMEF.........................................16
    4.   Limitations.............................................16
    4.1  IPFIX and IPv6..........................................17
    5.   Security Considerations.................................17
    6.   Normative References....................................17
    7.   Informative References..................................17
    8.   Acknowledgements........................................19
    9.   Author's Addresses......................................19
    10.  Full Copyright Statement................................20
    11.  Intellectual Property Statement.........................20
    12.  Copyright Statement.....................................21
    13.  Disclaimer..............................................21


 1. Introduction

    The IPFIX protocol defines how IP Flow information can be
    exported from routers, measurement probes or other devices. It
    is intended to provide this information as input for various





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    applications. IPFIX is a general data transport protocol, easily
    extensible to suit the needs of different applications. This
    document describes what applications can use the IPFIX protocol
    and how they can use it. Furthermore, the relationship of IPFIX
    to other frameworks and architectures is described.

 2. Applications of IPFIX

    IPFIX data enables several critical customer applications. This
    section describes how different applications can use IPFIX.

 2.1 Accounting

    Usage based accounting is one of the major applications for
    which the IPFIX protocol has been developed. IPFIX data provide
    fine-grained metering (for example, flow records include details
    such as IP addresses, packet and byte counts, timestamps, Type
    of Service (ToS), application ports, etc.) for highly flexible
    and detailed resource usage accounting. ISPs can use this
    information to migrate from single fee, flat-rate billing to
    more flexible charging mechanisms based on time of day,
    bandwidth usage, application usage, quality of service, etc.
    Enterprise customers can use this information for departmental
    chargeback or cost allocation for resource usage.

    In order to realize usage-based accounting with IPFIX the flow
    definition has to be chosen in accordance to the tariff model. A
    tariff can, for instance, be based on individual end-to-end
    streams. In that case accounting can be realized with a flow
    definition determined by the quintuple that consists of source
    address, destination address, protocol and port numbers. Another
    example is a class-dependent tariff (e.g. in a DiffServ
    network). For this flows could be distinguished just by DiffServ
    codepoint (DSCP) and source address.

    The essential elements needed for accounting are the number of
    transferred packets and bytes per flow which are contained in
    IPFIX flow records. Furthermore IPFIX provides a very flexible
    definition of flows, so arbitrary flow-based accounting models
    can be realized without any extensions to the IPFIX protocol.
    Nevertheless the configuration of flow definitions is out of
    scope of the IPFIX definition.

    For accounting purposes, it would be advantageous to have the
    ability to use IPFIX flow records as accounting input in an AAA
    infrastructure. AAA servers then could provide the mapping
    between user and flow information.






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 2.1.1 Example

    Letªs suppose someone has a Service Level Agreement (SLA) in a
    DiffServ network and has to be accounted based on the traffic
    volume. The information to export in this case is:
       - The source IP address (IPv4), so the length is 4
       - Type of Service
       - The number of bytes of the Flow

    The template set (in case we use only IETF specified Information
    Elements) will look like:


        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       Set ID = 2              |      Length = 17 bytes        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       Template ID 256         |       Field Count = 3         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     IP_SRC_ADDR = 0x0008      |       Field Length = 4        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | CLASS_OF_SERVICEIPv4 = 0x0005 |       Field Length = 1        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       IN_BYTES = 0x0001       |       Field Length = 4        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    The information to be exported is listed in the following table:


       Source IP address    |   Type of service   |   Bytes Number
                            |                     |
       ---------------------------------------------------------------
       192.181.17.0         |    101110          |   8987410
       192.180.17.8         |    101110          |   170205
       192.129.9.2          |    101110          |   33113

    The field ªªType of serviceªª contains the DiffServ Codepoint in
    the first six bits while the last two are currently unused. In
    the example we use Codepoint 101110, recommended for the EF PHB
    (Expedited Forwarding Per Hop Behavior)[RFC2598]


    The Flow Records will then look like:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+





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       |          Set ID = 256         |          Length = 32          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          192.181.17.0                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   101110 00   |                 8987410                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |               |               192.180.17.8                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |               |   101110 00   |                 170205        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               |         192.129.9.2           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                               |   101110 00   |               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   33113                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 2.2 Security Analysis and Intrusion Detection with IPFIX

    Intrusion detection systems (IDS) monitor and control security
    incidents. A typical IDS system includes components like sensor,
    event collector, and management stations. Sensors monitor
    network and system traffic for attacks and other security-
    related events. Sensors respond to and notify the administrator
    about these events as they occur. Event collectors are a middle-
    tier component responsible for transmitting events from sensors
    to the console and database. The management component serves the
    following purposes:

    - visually monitors events (with a console)
    - collects data from sensors (with one or more event collectors)
    - stores data from sensors (in a database)

    IPFIX can report events of interest to the sensor either by the
    collecting process or directly by the exporting process. Which
    approach is best depends on the scenario and the events of
    interest. Getting information directly from the exporting
    process has the advantage that the sensor gets the information
    faster. It does not need to wait for collector processing time
    or until the collector has all relevant data. Getting the
    information from a collector allows correlating data from
    different exporting processes (e.g. from different routers) to
    get a better picture of what is going on in the network.

    IPFIX provides useful input data for basic intrusion detection
    functions (e.g. detecting unusually high loads) such as details
    on source and destination addresses, along with the start time





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    of flows, TCP flags, application ports and flow volume. This
    data can be used to analyze network security incidents and
    identify attacks. Nevertheless, for some scenarios intrusion
    detection may require further insight into packet content. Since
    IPFIX allows a flexible report definition, the metering process
    and the IPFIX report format could be extended to support other
    data needed for intrusion detection systems.

    Detecting security incidents in real-time would require the pre-
    processing of data already at the measurement device and
    immediate data export in case a possible incident has been
    identified. This means that IPFIX reports must be generated upon
    incident detection events and not only upon flow end or fixed
    time intervals.

 2.3 Network Planning

    IPFIX data captured over a long period of time can be used to
    track and anticipate network growth and plan upgrades to
    increase the number of routing devices, ports, or higher-
    bandwidth interfaces. IPFIX data optimizes both strategic
    network planning (peering, backbone upgrade planning, and
    routing policy planning) as well as tactical network engineering
    decisions (upgrading the router or link capacity). This helps to
    minimize the total cost of network operations while maximizing
    network performance, capacity, and reliability.

 2.4 Peering Agreements

    IPFIX data enables ISP peering partners to measure the volume
    and characteristics of traffic exchanged with other ISP peers.
    ISP peering partners, consortia, or business coalitions can use
    IPFIX to exchange data between different domains. Having a means
    to share measurement data allows for more accurate end-to-end
    measurements. Through IPFIX data measured with different (often
    domain specific) tools can be exchanged and compared with data
    belonging to other domains.
    This is especially useful for inter-domain SLA validation where,
    in order to be able to provide accurate data, an ISP has to
    obtain measurements from other ISPs crossed in the end-to-end
    path.


 2.5 Traffic Engineering

    IPIFX data provides traffic engineering details for a set of
    prefixes. This data can be used in network optimization for load






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    balancing traffic across alternate paths, or for forwarding
    traffic of a certain set of prefixes on a preferred route.

 2.6 Data Warehousing and Mining

    IPFIX data (or derived information) can be stored for later
    retrieval and analysis to support proactive marketing and
    customer service programs. An example of this would be to
    determine which applications and services are being used by
    internal and external users and then target them for improved
    services such as advertising. This is especially useful for ISPs
    because IPFIX data enables them to create better service
    packaging.

 2.7 SLA validation

    Performing QoS monitoring is one target application of the IPFIX
    protocol. QoS monitoring is the passive observation of
    transmission quality for single flows or traffic aggregates in
    the network. One example of its usefulness is the validation of
    QoS guarantees in service level agreements (SLAs). Some QoS
    metrics require the correlation of data from multiple
    measurement points. For this the clocks of the involved
    exporting devices must be synchronized. Furthermore, such
    measurements would benefit from post-processing functions (e.g.
    packet ID generation and mapping) at the exporter and/or
    collector.

 2.8 Traffic Monitoring

    IPFIX data can be used for extensive near real-time traffic
    monitoring. Traffic patterns associated with routing devices and
    switches on an individual or network wide basis can be displayed
    enabling proactive problem detection, efficient troubleshooting,
    and rapid problem resolution.

    IPFIX data enables content and service providers to perform a
    detailed, time-based, and application-based usage analysis of a
    network. They also provide detailed information for
    understanding customer or end-user usage of network and
    application resources. This information can then be used to
    efficiently plan and allocate access, backbone, and application
    resources, as well as to detect and resolve potential security
    and policy violations.


    This section describes how the monitoring of different metrics
    can be performed with IPFIX. All of the metrics require at least





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    an extension of the IPFIX information model because the
    necessary information such as round-trip-time, packet Ids, etc.,
    is currently not part of the model. However given the
    extensibility and flexibility of IPFIX the missing attributes
    can be easily defined.

 2.8.1   Measurement of Round-trip-time (RTT)

    The passive measurement of round-trip-times (RTT) can be
    performed by using packet pair matching techniques as described
    in [Brow00]. For the measurements, request/response packet pairs
    from protocols such as DNS, ICMP, SNMP or TCP (syn/syn-ack,
    data/ack) are utilized to passively observe the RTT [Brow00]. As
    always, this only works for passive measurements if the required
    traffic of interest is actually present in the network.
    Furthermore, if the observed protocol supports retransmissions
    (e.g. TCP) the RTT is not the network RTT but rather the RTT of
    the network and the protocol stack of the receiver. In case the
    reply packet is lost or can not be observed the RTT can not be
    calculated.

    In order to use this measurement technique, the IPFIX metering
    process needs to measure in both directions. A classification of
    the protocols mentioned above has to be done. That means parts
    of the transport header are used for the classification. Since a
    differentiation of flows in accordance to the transport header
    is one of the requirements for IPFIX, such classification can be
    performed without extensions. Nevertheless, the meter needs to
    recognize request and response packets for the given protocols
    and therefore needs to look further into the packets. The
    capability to do this analysis is not part of the IPFIX
    requirements but can be achieved by optional extensions to the
    classification process. The exporting device needs to assign a
    timestamp for the arrival of the packets. The calculation of the
    RTT can be done directly at the exporter or at the collector. In
    the first case IPFIX would transfer the calculated RTT to the
    collector. In the second case IPFIX needs to send the observed
    packet types and the timestamps to the collector. The round-
    trip-time-delay metric is defined in [RFC2681].

 2.8.2   Measurement of One-way-delay (OWD)

    Passive one-way-delay measurements require the collection of
    data at two measurement points. It is necessary to recognize
    packets at the second measurement point to correlate packet
    arrival events from both points. This can be done by capturing
    packet header and parts of the packet that can be used to
    recognize the same packet at the subsequent measurement point.





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    To reduce the amount of measurement data a unique packet ID can
    be calculated from the header and part and/of the content e.g.
    by using a CRC or hash function [GrDM98, DuGr00, ZsZC01]. The
    capability of using content information is out of scope of IPFIX
    but can be achieved by an optional extension. Nevertheless, in
    some scenarios it might even be sufficient to calculate a packet
    ID based on header fields (including datagram ID and maybe
    sequence numbers from transport protocols) without looking at
    parts of the packet content. If packet IDs need to be unique
    only for a certain time interval or a certain amount of packet
    ID collisions is tolerable this is a sufficient solution. The
    second issue is the export of packet IDs. IPFIX exports per flow
    information. However, it is possible to extend IPFIX with a
    scheme to export per-packet information by providing special
    templates for that purpose. The one way delay metric is defined
    in [RFC2679].

 2.8.3   Measurement of One-way-loss (OWL)

    Passive loss measurements for single flows can be performed at
    one measurement point by using sequence numbers that are present
    in protocols (e.g. IP identification, TCP sequence numbers)
    similar to the approach described in section 2.8.1. This
    requires the capturing of the sequence numbers of subsequent
    packets of the observed flow by the IPFIX metering process.

    An alternative to this is to perform a two-point measurement as
    described in section 2.8.2 and consider packets as lost that do
    not arrive at the second measurement point in a given time
    frame. This approach assumes that a packet observed at the first
    point should also be observed at the second point (known
    routing).

    The one-way loss metric is defined in [RFC2680].

 2.8.4 Measurement of IP delay variation (IPDV)

    IP Delay variation is defined as the difference of one-way-delay
    values for selected packets [RFC3393]. Therefore, this metric
    can be calculated by performing passive measurement of one-way-
    delay for subsequent packets (e.g. of a flow) and then
    calculating the differences.

 3. Relation of IPFIX to other frameworks and protocols

 3.1 IPFIX and AAA

    AAA defines a protocol and architecture for authentication,
    authorization and accounting for service usage. The DIAMETER





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    protocol is used for AAA communication for network access
    services (Mobile IP, NASREQ, and ROAMOPS). The AAA architecture
    [RFC2903] provides a framework for extending the AAA support
    also for other services. DIAMETER defines the exchange of
    messages between AAA entities, e.g. between AAA clients at
    access devices and AAA servers and among AAA servers. It is used
    also for the transfer of accounting records. Usage-based
    accounting requires measurement data from the network. IPFIX
    defines a protocol to export such data from routers, measurement
    probes and other devices.

    The provisioning of accounting with IPFIX can be realized
    without an AAA infrastructure. The collector can directly
    forward the measurement information to an accounting
    application. Nevertheless, if an AAA infrastructure is in place,
    IPFIX can provide the input for the generation of accounting
    records and several features of the AAA architecture can be
    used. Features include the mapping of a user ID to the flow
    information (by using authentication information), the
    generation of DIAMETER accounting records and the secure
    exchange of accounting records between domains with DIAMETER.
    Two possibilities to connect IPFIX and AAA can be distinguished:

 3.1.1 Connecting via an AAA Client

    One possibility means of connecting IPFIX and AAA is to run an
    AAA client on the IPFIX collector. This client can generate
    DIAMETER accounting messages and send them to an AAA server. The
    mapping of the flow information to a user ID can be done in the
    AAA server by using data from the authentication process.
    DIAMETER accounting messages can be sent to the accounting
    application or to other AAA servers (e.g. in roaming scenarios).





















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           +---------+  DIAMETER    +---------+
           |  AAA-S  |------------->|  AAA-S  |
           +---------+              +---------+
                ^
                | DIAMETER
                |
                |
         +--+--------+--+
         |  |  AAA-C |  |
         +  +--------+  |
         |              |
         |  Collector   |
         +--------------+
                ^
                | IPFIX
                |
          +------------+
          |  Exporter  |
          +------------+

    Figure 2: IPFIX collector connects to AAA server via AAA client

 3.1.2 Connecting via an Application Specific Module (ASM)

    Another possibility is to directly connect the IPFIX collector
    with the AAA server via an application specific module (ASM).
    Application specific modules have been proposed by the IRTF AAA
    architecture research group (AAARCH) in [RFC2903]. They act as
    an interface between AAA server and service equipment. In this
    case the IPFIX collector is part of the ASM. The ASM acts as an
    interface between the IPFIX protocol and the input interface of
    the AAA server. The ASM translates the received IPFIX data into
    an appropriate format for the AAA server. The AAA server then
    can add information about the user ID and generate a DIAMETER
    accounting record. This accounting record can be sent to an
    accounting application or to other AAA servers.
















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           +---------+  DIAMETER    +---------+
           |  AAA-S  |------------->|  AAA-S  |
           +---------+              +---------+
                ^
                |
        +------------------+
        |     ASM          |
        |  +------------+  |
        |  |  Collector |  |
        +------------------+
                ^
                | IPFIX
                |
          +------------+
          |  Exporter  |
          +------------+

    Figure 3: IPFIX connects to AAA server via ASM

 3.2 IPFIX and RTFM


    This section compares the Real-time Traffic Flow Measurement
    (RTFM) framework with the IPFIX framework.

 3.2.1    Flow Definition





    RTFM and IPFIX both use the same definition of flow; a flow is a
    set of packets which share a common set of end-point address
    attribute values. A flow is therefore completely specified by
    that set of values, together with an inactivity timeout.  A flow
    is considered to have ended when no packets are seen for at
    least the inactivity time.

    RTFM flows, however, are bidirectional, i.e. an RTFM meter
    matches packets from B to A and A to B as separate parts of a
    single flow, and maintains two sets of packet and byte counters,
    one for each direction. IPFIX flow are unidirectional; users
    needing bidirectional flows will need to match the two
    directions in post-processing.

 3.2.2   Configuration and Management

    In RTFM, remote configuration (using an SNMP MIB) is the only
    way to configure a meter.  IPFIX, however, makes no provision
    for remote configuration - meters must be configured locally by





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    a System Administrator. IPFIX meters export their configuration,
    i.e. the layout of data within their templates, from time to
    time.
    IPFIX collectors use that template information to determine how
    they should interpret the IPFIX flow data they receive.

    An IPFIX meter must normally be configured to export data to a
    specified list of IPFIX collectors, i.e. data is pushed out by
    the meter.  In contrast, an RTFM meter reader pulls data from a
    meter; SNMP security (data view) on the meter determines whether
    a reader is allowed to pull data from it.

 3.2.3    Data Model Details

    RTFM defines all its attributes in the RTFM Meter MIB [RFC
    2720], and IPFIX defines its information elements in the IPFIX
    Information Model document.





    In IPFIX, fields such as ToPDUs and FromPDUs are stored in 64-
    bit counters.  Exported flows carry such counter values as they
    were after the flow's last packet.  Long-running flows may be
    broken into a sequence of shorter flows; in that case the flow
    counters are zeroed when the flow is exported.

    RTFM uses continuously-incrementing 64-bit counters, which are
    never reset.  Instead, flows can be read at any time; the
    difference between counter readings gives the counts for
    activity in the interval between readings.






 3.2.4   Application/Transport Protocol

    RTFM has a standards-track Meter MIB [RFC 2720], which can be
    used both to configure a meter and to read flow data from it.
    The MIB provides a way to read lists of attributes with a single
    Object Identifier (called a 'package'), which dramatically
    reduces the SNMP overhead for flow data collection. SNMP, of
    course, normally uses UDP as its transport protocol. Since RTFM
    requires a reliable flow data transport system, an RTFM meter
    reader must time out and resend unanswered SNMP requests. Apart
    from being clumsy, this can limit the maximum data transfer rate
    from meter to meter reader.

    IPFIX is designed to work over a variety of different transport
    protocols.  The preferred protocol is SCTP (either reliable or
    partially reliable) or TCP.  In addition, the IPFIX protocol


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    encodes data much more efficiently than does SNMP, hence IPFIX
    will have lower data transport overheads than RTFM.

    A need for high flow data rates highlights the need for careful
    systems design when building a flow data collection system.
    When data rates are high, and it is not possible to use a high
    level of aggregation, then it makes sense to have the collectors
    very close to their exporters.  Once the data is safely on a
    dedicated host machine, large volumes of it can be moved using
    'background' techniques such as FTP.

 3.2.5   RTFM Summary

    IPFIX is designed to be a simple, high-performance system for
    exporting flow data from a meter, making it highly suitable for
    that purpose.  RTFM provides bi-directional flows, dynamic
    configuration, and the ability to work with much more general
    definitions of flow end-points.  It may continue to be more
    suitable in 'research' situations which need those features.
    Another difference between the two systems is that while RTFM
    works in ªpullª mode, IPFIX uses ªpushª mode.

 3.3 IPFIX and IPPM

    The IPFIX protocol can be used to carry IPPM network performance
    metrics or information that can be used to calculate those
    metrics (see section 2.8).

 3.4 IPFIX and PSAMP

    There is currently a very dynamic relation between IPFIX and
    PSAMP. PSAMP defines, between others, the information to be
    reported on sampled packets, describes the protocol by which
    this information is reported and the protocol by which the
    packet reporting is configured. The major difference between
    IPFIX and PSAMP protocols is that while the former exports flow
    records, the latter exports packet records.
    The Working Group describes in [PSAMP-FM] a set of requirements
    that affect directly the export protocol. In [PSAMP-PROTOCOL]
    the requirements have been analyzed with respect to IPFIX and
    the conclusion is that IPFIX is an exporting protocol general
    enough to be suitable for PSAMP. If needed, the information
    model can be easily extended.


 3.5 IPFIX and RMON






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    RMON [RFC 3577] is a widely used monitoring system that gathers
    traffic data from RMON Agents in network devices in a general
    way using SNMP. The RMON MIB is divided into sections, each
    section providing different monitoring functions.  For example,
    the 'Hosts' section gathers statistics for hosts which are
    active on the network being monitored.

    RMON does not cover flow measurement at all. To do so, one would
    need to extend RMON by adding a MIB module to handle flows.
    Further, one would need to devise a scheme for exporting high
    volumes of flow data. In short, IPFIX is designed to provide
    effective flow export: RMON is not.


 3.6 IPFIX and IDMEF

    The Intrusion Detection Message Exchange Format (IDMEF) [CuDF04]
    is a standard data format developed within the IDWG Working
    Group to exchange data alerts between automated Intrusion
    Detection Systems (IDS). IDMEF provides a standard
    representation of the alert information that an Intrusion
    Detection analyzer reports when a suspicious event is detected.
    These alerts may be simple or complex depending on analyzers
    capabilities, commercial vendor objectives, and intrusion
    detection environments. IDMEF messages are implemented in XML
    and composed by a basic schema and extension modules to define
    alerts that are more complex. Once the kind of alert that should
    be sent has been determined by the analyzer, it must be
    formatted following the IDMEF rules.
    Generally, alerts are sent when analyzers detect an event that
    they have been configured to look for.
    The IPFIX protocol can be used complementarily to IDMEF for
    providing detailed information of intrusions traffic, suspect
    events or anomalous traffic that differs from normal network
    behavior.


 4. Limitations

    The goal of this section is to give recommendations where not to
    use IPFIX. While the protocol is general enough to be adequate
    for exporting flow data in many applications, it still has
    limitations.

    SCTP is the preferred protocol for IPFIX, i.e. a conforming
    implementation must work over SCTP. Although IPFIX can also work






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    over TCP or UDP -
                    - users make sure they have good reasons for
    using protocols other than SCTP.

    IPFIX works in ªpushª mode that is data are automatically
    exported without waiting for a request. It is therefore a sub-
    optimal solution when the monitoring configuration needs to be
    changed often. ªPullª modewould be in that case more
    appropriate.

    In case of many exports, requiring many different templates, the
    Template IDs could not be enough


 4.1 IPFIX and IPv6
    There is no problem in reporting IPv6 data with IPFIX, provided
    only that the transport protocol being used to carry IPFIX (SCTP
    is preferred) is running on the IPv6 network.


 5. Security Considerations

    This document describes the usage of IPFIX in various scenarios.
    The security requirements for the IPFIX target applications are
    addressed in the IPFIX requirements draft. These requirements
    must be considered for the specification of the IPFIX protocol.
    The IPFIX extensions proposed in this document do not induce
    further security hazards.

    Section 3 of this document describes how IPFIX can be used in
    combination with other frameworks. New security hazards can
    arise when two individually secure frameworks are combined. For
    the combination of AAA with IPFIX an ASM or an IPFIX collector
    can function as transit point for the messages. It has to be
    ensured that at this point the applied security mechanisms (e.g.
    encryption of messages) are maintained.

 6. Normative References

    [RFC3917]    J. Quittek, T. Zseby, B. Claise, S. Zander,
                  ªªRequirements for IP Flow Information Export ",
                  October 2004

 7. Informative References

    [Awdu02]     Daniel O. Awduche, et. al.," Overview and
                  Principles of Internet Traffic Engineering", (work
                  in progress), Internet Draft, Internet Engineering






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                  Task Force, draft-ietf-tewg-principles-02.txt, May
                  2002

    [Brow00]     Nevil Brownlee: Packet Matching for NeTraMet
                  Distributions,http://www2.auckland.ac.nz/net//Inter
                  net/rtfm/meetings/47-adelaide/pp-dist/

    [CuDF04]     D.Curry, H. Debar, H. Feinstein: ªªThe Intrusion
                  Detection Message Exchange Formatªª,(work in
                  progress), Internet Draft, Internet Engineering
                  Task Force, <draft-ietf-idwg-idmef-xml-11.txt>,
                  January 2004

    [DuGr00]     Nick Duffield, Matthias Grossglauser: "Trajectory
                  Sampling for Direct Traffic Observation",
                  Proceedings of ACM SIGCOMM 2000, Stockholm, Sweden,
                  August 28 - September 1, 2000.

    [GrDM98]     Ian D. GRAHAM, Stephen F. DONNELLY, Stele MARTIN,
                  Jed MARTENS, John G. CLEARY: Nonintrusive and
                  Accurate Measurement of Unidirectional Delay and
                  Delay Variation on the Internet, INET'98, Geneva,
                  Switzerland,  21-24 July, 1998

    [PSAMP-FW]   Nick Duffield (Ed.): A Framework for Packet
                  Selection and Reporting, Internet Draft draft-ietf-
                  psamp-framework-08, work in progress, January 2005

    [RFC2598]    V. Jacobson, K. Nichols, K. Poduri, An Expedited
                  Forwarding PHB, Request for Comments: 2598, June
                  1999

    [RFC2679]    G. Almes, S. Kalidindi, M. Zekauskas: A One-way
                  Delay Metric for IPPM, Request for Comments: 2679,
                  September 1999

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

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

    [RFC2903]    C. de Laat, G. Gross, L. Gommans, J. Vollbrecht, D.
                  Spence, "Generic AAA Architecture", RFC 2903,
                  August 2000

    [RFC3393]    C. Demichelis, P. Cimento: IP Packet Delay
                  Variation Metric for IPPM, RFC 3393, November 2002





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    [RFC3577]    S. Waldbusser, R. Cole, C. Kalbfleisch,
                  D.Romascanu: Introduction to the Remote Monitoring
                  (RMON) Family of MIB Module, RFC 3577,

    [ZsZC01]     Tanja Zseby, Sebastian Zander, Georg Carle:
                  Evaluation of Building Blocks for Passive One-way-
                  delay Measurements, Proceedings of Passive and
                  Active Measurement Workshop (PAM 2001), Amsterdam,
                  The Netherlands, April 23-24, 2001


 8. Acknowledgements

    We would like to thank the following persons for their
    contribution, discussion on the mailing list and valuable
    comments:

    Sebastian Zander
    Robert Loewe
    Reinaldo Penno

    Part of the work has been developed in the research project 6QM
    co-funded with support from the European Commission.

 9. Author's Addresses

    Tanja Zseby
    Fraunhofer Institute for Open Communication Systems (FOKUS)
    Kaiserin-Augusta-Allee 31
    10589 Berlin, Germany
    Phone: +49 30 3463 7153
    Email: zseby@fokus.fhg.de

    Elisa Boschi
    Fraunhofer Institute for Open Communication Systems (FOKUS)
    Kaiserin-Augusta-Allee 31
    10589 Berlin, Germany
    Phone: +49 30 3463 7366
    Email: boschi@fokus.fhg.de

    Nevil Brownlee
    CAIDA (UCSD/SDSC)
    9500 Gilman Drive
    La Jolla, CA 92093-0505
    Phone : +1 858 534 8338
    Email : nevil@caida.org






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    Benoit Claise
    Cisco Systems
    De Kleetlaan 6a b1
    1831 Diegem
    Belgium
    Phone: +32 2 704 5622
    Email: bclaise@cisco.com

 10.Full Copyright Statement

    "Copyright (C) The Internet Society (2005). All Rights Reserved.
    This document and translations of it may be copied and furnished
    to others, and derivative works that comment on or otherwise
    explain it or assist in its implementation may be prepared,
    copied, published and distributed, in whole or in part, without
    restriction of any kind, provided that the above copyright
    notice and this paragraph are included on all such copies and
    derivative works. However, this document itself may not be
    modified in any way, such as by removing the copyright notice or
    references to the Internet Society or other Internet
    organizations, except as needed for the purpose of developing
    Internet standards in which case the procedures for copyrights
    defined in the Internet Standards process must be followed, or
    as required to translate it into.


 11. Intellectual Property Statement

    The IETF has been notified by Cisco of intellectual property
    rights claimed in regard to some or all of the specification
    contained in this document. For more information, see
    http://www.ietf.org/ietf/IPR/cisco-ipr-draft-ietf-ipfix-as-
    02.txt

    The IETF takes no position regarding the validity or scope of
    any Intellectual Property Rights or other rights that might be
    claimed to pertain to the implementation or use of the
    technology described in this document or the extent to which any
    license under such rights might or might not be available; nor
    does it represent that it has made any independent effort to
    identify any such rights.  Information on the procedures with
    respect to rights in RFC documents can be found in BCP 78 and
    BCP 79.

    Copies of IPR disclosures made to the IETF Secretariat and any
    assurances of licenses to be made available, or the result of an
    attempt made to obtain a general license or permission for the
    use of such proprietary rights by implementers or users of this





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    specification can be obtained from the IETF on-line IPR
    repository at http://www.ietf.org/ipr.

    The IETF invites any interested party to bring to its attention
    any copyrights, patents or patent applications, or other
    proprietary rights that may cover technology that may be
    required to implement this standard.  Please address the
    information to the IETF at ietf-ipr@ietf.org.

 12. Copyright Statement

    Copyright (C) The Internet Society (2005).  This document is
    subject to the rights, licenses and restrictions contained in
    BCP 78, and except as set forth therein, the authors retain all
    their rights.

 13. Disclaimer

    This document and the information contained herein are provided
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    REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND
    THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY
    THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY
    RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
    FOR A PARTICULAR PURPOSE.



























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