IPFIX Working Group                                    B. Claise
     Internet-Draft                                         P. Aitken
     Intended Status: Informational                        A. Johnson
     Expires: August 25, 2008                     Cisco Systems, Inc.
                                                             G. Muenz
                                              University of Tuebingen
                                                    February 25, 2008
     
                       IPFIX Export per SCTP Stream
               draft-claise-ipfix-export-per-sctp-stream-03
     
     
     Status of this Memo
     
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     Copyright Notice
     
        Copyright (C) The IETF Trust (2008).
     
     
     
     
     
     
     
     
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     Abstract
     
        This document specifies an improvement to the use of SCTP
        as specified in the IPFIX specifications in order to be
        able to deduce the data record loss per template record in
        case of partially-reliable SCTP export.  This specification
        offers several extra advantages: immediate export of the
        template withdrawal message, immediate reuse of template ID
        within a stream, and the collecting process's job is
        easier.
     
     Conventions used in this document
     
        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].
     
     
     Table of Contents
     
     
        1. Terminology...............................................4
           1.1. IPFIX Documents Overview.............................4
           1.2. PSAMP Documents Overview.............................4
        2. Introduction..............................................5
           2.1. Applicability........................................6
        3. IPFIX Protocol Specifications Limitations and Improvements6
           3.1. Data Record Loss per Template........................6
              3.1.1. IPFIX Protocol Specifications Limitation........6
              3.1.2. IPFIX Export per SCTP Stream Advantage..........7
           3.2. Transmission Order within a Stream...................7
              3.2.1. IPFIX Protocol Specifications Limitation........7
              3.2.2. IPFIX Export per SCTP Stream Advantages.........8
           3.3. No Transmission Order across SCTP Streams............8
              3.3.1. IPFIX Protocol Specifications Limitation........8
              3.3.2. IPFIX Export per SCTP Stream Advantages.........9
        4. Specifications............................................9
           4.1. Template Management..................................9
           4.2. Template Withdrawal Message.........................10
           4.3. SCTP................................................11
           4.4. The Collecting Process's Side.......................12
        5. Examples.................................................12
        6. IANA Considerations......................................15
        7. Security Considerations..................................15
        8. References...............................................15
     
     
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           8.1. Normative References................................15
           8.2. Informative References..............................16
        9. Acknowledgements.........................................17
        10. Author's Addresses......................................18
        11. Intellectual Property Statement.........................19
        12. Copyright Statement.....................................19
        13. Disclaimer..............................................19
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     1. Terminology
     
        IPFIX-specific terminology used in this document is defined
        in section 2 of [RFC5101].  As in [RFC5101], these IPFIX-
        specific terms have the first letter of a word capitalized
        when used in this document.
     
        Template Reuse Delay
     
           The configurable timeout to allow the Collecting Process
           to receive and process the last Data Record using this
           Template information before which the Template Withdrawal
           Message MUST NOT be sent.  [RFC5101] specifies a default
           value of 5 seconds.
     
     
     1.1. IPFIX Documents Overview
     
        The IPFIX Protocol [RFC5101] provides network administrators
        with access to IP flow information.
     
        The architecture for the export of measured IP flow
        information out of an IPFIX exporting process to a collecting
        process is defined in the IPFIX Architecture [IPFIX-ARCH],
        per the requirements defined in RFC 3917 [RFC3917].
     
        The IPFIX Architecture [IPFIX-ARCH] specifies how IPFIX Data
        Records and Templates are carried via a congestion-aware
        transport protocol from IPFIX Exporting Processes to IPFIX
        Collecting Processes.
     
        IPFIX has a formal description of IPFIX Information Elements,
        their name, type and additional semantic information, as
        specified in the IPFIX Information Model [RFC5102].
     
        Finally the IPFIX Applicability Statement [IPFIX-AS]
        describes what type of applications can use the IPFIX
        protocol and how they can use the information provided.  It
        furthermore shows how the IPFIX framework relates to other
        architectures and frameworks.
     
     1.2. PSAMP Documents Overview
     
        The document "A Framework for Packet Selection and Reporting"
        [PSAMP-FMWK], describes the PSAMP framework for network
        elements to select subsets of packets by statistical and
     
     
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        other methods, and to export a stream of reports on the
        selected packets to a collector.
     
        The set of packet selection techniques (sampling, filtering,
        and hashing) supported by PSAMP are described in "Sampling
        and Filtering Techniques for IP Packet Selection" [PSAMP-
        TECH].
     
        The PSAMP protocol [PSAMP-PROTO] specifies the export of
        packet information from a PSAMP Exporting Process to a PSAMP
        Collecting Process.  Like IPFIX, PSAMP has a formal
        description of its information elements, their name, type and
        additional semantic information.  The PSAMP information model
        is defined in [PSAMP-INFO].
     
        Finally [PSAMP-MIB] describes the PSAMP Management
        Information Base.
     
     
     2. Introduction
     
        The IPFIX working group has specified a protocol to export IP
        Flow information [RFC5101].  This protocol is designed to
        export information about IP traffic flows and related
        measurement data, where a flow is defined by a set of key
        attributes (e.g. source and destination IP address, source
        and destination port, etc.). However, thanks to its template
        mechanism, the IPFIX protocol can export any type of
        information, as long as the relevant Information Element is
        specified in the IPFIX Information Model [RFC5102],
        registered with IANA, or specified as an enterprise-specific
        Information Element.
     
        The IPFIX protocol [RFC5101] specifies that IP traffic
        measurements for flows are exported using a TLV (type,
        length, value) format.  The information is exported using a
        Template Record that is sent once to export the {type,
        length} pairs that define the data format for one or more
        Data Records that are sent for a flow.  The Data Records
        specify values for each flow.
     
        The IPFIX protocol [RFC5101] is flexible: it foresees the usage
        of the multiple SCTP streams per association; allows the
        transmission of Data Sets, Template Sets, and/or Options
        Template Sets on any stream; it offers the full or partial
        reliability export of Data Sets; it proposes the ordered or out-
        of-order delivery of Data Sets.  However, due the resource
     
     
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        constraints on the Exporter, it is not always possible to export
        all Data Sets in a reliable way.
     
        The specification in this document offers several advantages
        such as: the data records loss per template record in case of
        partially-reliable SCTP export, immediate export of the Template
        Withdrawal Message, immediate reuse of template ID within a
        stream, reduce the likelihood of losing data record, and the
        collecting process's job is easier.
     
     
     2.1. Applicability
     
        The specification in this document applies to the IPFIX
        protocol specifications [RFC5101].  However, it only applies
        to the SCTP transport [RFC4960] and [RFC3758] protocol option
        of the IPFIX protocol specifications.  All specifications
        from [RFC5101] apply unless specified otherwise in this
        document.
     
        As the Packet Sampling (PSAMP) protocol specifications
        [PSAMP-PROTO] are based on the IPFIX protocol specifications,
        the specifications in this document are also valid for the
        PSAMP protocol.  Therefore, the advantages specified by this
        document also apply to PSAMP.
     
     
     3. IPFIX Protocol Specifications Limitations and Improvements
     
     3.1. Data Record Loss per Template
     
     3.1.1. IPFIX Protocol Specifications Limitation
     
        Section 6.3.2 of the Requirements for IP Flow Information
        Export [RFC3917] discusses the data transfer reliability
        issues.  "Loss of flow records during the data transfer from
        the exporting process to the collecting process must be
        indicated at the collecting process." is clearly mentioned.
        However, in some cases, it may be important to know how many
        Data Records of a certain type were lost (e.g., in the case
        of billing), but conventionally IPFIX does not provide this
        information.
     
        A Collector can detect out-of-sequence, dropped, or duplicate
        IPFIX Messages by tracking the Sequence Number [RFC5101].
        However, the Sequence Number field in the Export header
     
     
     
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        increases with the number of IPFIX Data Records with the PR-
        SCTP stream.
     
        The IPFIX protocol specification [RFC5101] specifies that Data
        Records associated with any Template ID may be sent on any SCTP
        stream.  As such, if there is more than one Template IDs defined
        within the whole SCTP association then there is no way of
        knowing the which Template ID any lost Data Records are
        associated with.  This is true, now matter what convention
        the Exporting Process uses to send Data Records on different
        SCTP streams, as the protocol makes no guarantees.
     
        Using the specification in this document, it is guaranteed that
        any lost Data Records will be associated only with the Templates
        that are defined on that stream and by defining only one
        Template on a stream it is ensured that any loss is associated
        with that single Template.
     
     
     3.1.2. IPFIX Export per SCTP Stream Advantage
     
        By exporting each Template ID and the corresponding Data Records
        within a different stream, the loss pertaining to each specific
        Template ID can be deduced from Sequence Number field in the
        Export headers.
     
     
     3.2. Transmission Order within a Stream
     
     3.2.1. IPFIX Protocol Specifications Limitation
     
        A Collecting Process must have received the Template Record
        associated with the Data Records to be able to decode the
        information in the Data Records.  The IPFIX protocol
        specification foresees:
     
           "The Exporting Process SHOULD transmit the Template Set
           and Options Template Set in advance of any Data Sets that
           use that (Options) Template ID, to help ensure that the
           Collector has the Template Record before receiving the
           first Data Record.",
     
        The fact that the Collecting Process cannot decode the Data
        Records without the Template Record may result in the Data
        Records being discarded by the Collector, as specified in
        [RFC5101]:
     
     
     
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           "The Collecting Process normally receives Template Records
           from the Exporting Process before receiving Data Records.
           The Data Records are then decoded and stored by the
           Collector.  If the Template Records have not been received
           at the time Data Records are received, the Collecting
           Process MAY store the Data Records for a short period of
           time and decode them after the Template Records are
           received."
     
        In practice, Data Records without associated (Options)
        Template Records will probably be discarded by the Collecting
        Process.
     
     
     3.2.2. IPFIX Export per SCTP Stream Advantages
     
        By exporting each Template Record and the corresponding Data
        Records within a single stream and imposing in-order
        transmission, the Template will always arrive before the
        associated Data Records.  Therefore, there is no risk that
        the Collecting Process discards Data Records while waiting
        for the Template to arrive.
     
        Furthermore, when reusing a Template ID within a stream, the
        Template Withdrawal Message will be guaranteed to arrive
        before the new definition of the Template and therefore the
        Template Record may be sent directly after the Template
        Withdrawal Message.  Therefore the Template Reuse Delay
        restriction can be removed for Template ID reuse with a
        stream.
     
        Another advantage with the new specifications in this
        document is that the Collecting Process's job is now easier.
        Indeed, the Collecting Process doesn't have to store the Data
        Records while waiting for the Template Records, as the
        transmission order is always guaranteed.  This way, extra
        reliability of the Data Records is achieved without extra
        burden on the Collecting Process.
     
     
     3.3. No Transmission Order across SCTP Streams
     
     3.3.1. IPFIX Protocol Specifications Limitation
     
        The fact that the protocol specifications [RFC5101] are
        flexible in terms of stream(s) on which the Template Set,
        Options Template Set, and corresponding Data Sets are
     
     
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        exported, implies that the (Options) Template Set might be
        exported on a different stream than the corresponding Data
        Sets.  This might cause Data Record loss in the Collecting
        Process as the ordered transmission across SCTP streams is
        not guaranteed.
     
        For example, a Template may be blocked pending reliable
        transmission on one stream while the associated Data Records
        may be transmitted immediately in another stream.  Also, due
        to different stream congestion, it is possible that even if
        the Template and Data Records are both sent reliably, Data
        Records sent on a different stream than the associated
        Template might still arrive before the associated Template.
     
     
     3.3.2. IPFIX Export per SCTP Stream Advantages
     
        By exporting each Template Record and the corresponding Data
        Records within a single stream, imposing in-order
        transmission, and limiting the Template ID to a single
        stream, the issue of ordered transmission across multiple
        streams is avoided.
     
        By exporting all corresponding Data Records within the same
        ordered stream as the Template Definition then each stream is
        independent and self-contained and the interaction between
        streams is limited to that of Options Data interactions.  This
        has several advantageous consequences, including order
        preservation does not result in the blocking of unrelated data
        and that the Collector's job is simplified as the Template
        Records are guaranteed to be delivered before the associated
        Data Records.
     
     
     4. Specifications
     
     4.1. Template Management
     
        This section introduces modifications compared to the Template
        Management section 8 in [RFC5101].
     
        As specified in [RFC5101], Template Sets and Options Template
        Sets MUST be sent reliably.   In other words, any IPFIX Message
        containing an (Options) Template Set MUST be sent reliably.
     
        Any Data Sets associated with a Template Record MUST be sent on
        the same stream on which the Template Record was sent.
     
     
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        By sending only a single Template ID and associated Data Sets
        within a single stream, any Data Record loss can be calculated
        on a per Template basis.
     
        If there is some Options Data Records required to interpret the
        Data Records, the Options Data Records MUST be sent reliably
        within the same stream.  If not sent reliably, the Collector
        could consider that any loss might be associated with the
        Options Template Record, even if the Exporter is always sending
        them reliably.
     
        The Option Data Record SHOULD be sent before the Data Record
        that needs it so that it arrives first and is available for the
        Collector to use.  By sending the Options Data reliably, any
        loss will be limited to the non-option Data Record and loss can
        still be calculated on a per
        Template basis.
     
        Furthermore, the Exporter MAY group related Template IDs and
        their associated Data Sets within a single stream so loss
        statistics are calculated for the group.  This may be suitable
        in cases where there is insufficient SCTP streams to send each
        Template on its own stream and/or the case where there are
        slight variations on a single Template to show that some fields
        were unavailable at the time of monitoring.
     
     
     
     4.2. Template Withdrawal Message
     
        This section introduces Template Withdrawal Message-related
        modifications compared to the Template Management section 8 in
        [RFC5101].
     
        Templates that are not used anymore SHOULD be deleted.  Before
        reusing a Template ID, the Template MUST be deleted.  In order
        to delete an allocated Template, the Template is withdrawn
        through the use of a Template Withdrawal Message.  The Template
        Withdrawal Message MUST be sent on the same stream as the
        Template ID to be removed.
     
        As all IPFIX Messages are sent in order within a stream and
        reliably per [RFC5101], the IPFIX Message containing the
        Template Withdrawal Message will not arrive at the Collecting
        Process before any associated and previously sent Data Record.
     
     
     
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        As a consequence, no Data Records will be lost due to delayed
        arrival at the Collector.
     
        The Template ID from a withdrawn Template MAY be reused on the
        same stream immediately after the Template Withdrawal Message is
        sent. This case is equivalent to the use of a Template Reuse
        Delay value of 0.
     
        If the new definition of the Template ID is to be reused on a
        different stream, the Template Withdrawal Message MUST NOT be
        sent before the Template Reuse Delay.
     
        A Template Withdrawal Message to withdraw all Templates for the
        Observation Domain ID specified in the IPFIX Message header MUST
        NOT be used.
     
        Multiple Template IDs MAY be withdrawn with a single Template
        Withdrawal Message at the condition that all the Template IDs in
        the Template Withdrawal Message are used on the same SCTP
        stream.
     
     4.3. SCTP
     
        This section introduces modifications compared to the "SCTP"
        section 10.2 (and subsections) in [RFC5101].  More specifically
        the "Stream" section 10.2.4.3
     
        PR-SCTP [RFC3758] MUST be implemented by all compliant
        implementations.
     
        All IPFIX Messages MUST be sent in order within a stream.
     
        Depending on the application requirement, the Exporting Process
        MAY send Data Sets with full or partial reliability. Unreliable
        data transfer MAY be used where the application does not require
        reliable transmission and the use of a retransmission queue is
        impractical.
     
        If the Exporting Process requires to export a new Template but
        there are no more free SCTP streams available, it SHOULD attempt
        to increase the number of outbound streams it is able to send
        to, per [SCTP-RESET].  Alternatively, the Exporting Process MAY
        add the Template Set and Data Records to an existing stream at
        the cost of diluting the granularity of Data Records loss.
     
     
     
     
     
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     4.4. The Collecting Process's Side
     
        This refers to the Collecting Process's Side section 9 in
        [RFC5101].
     
        The Collecting Process SHOULD listen for a new association
        request from the Exporting Process.  The Exporting Process will
        request a number of streams to use for export: the number of
        streams SHOULD be equivalent to the number of simultaneous
        Template IDs used in the association.
     
        A Collecting process SHOULD support the procedure for the
        addition of a SCTP stream [SCTP-RESET].
     
        The IPFIX protocol has a Sequence Number field in the Message
        header that increases with the number of IPFIX Data Records in
        the IPFIX Message.  A Collector may detect out-of-sequence,
        dropped, or duplicate IPFIX Messages by tracking the Sequence
        Number.  As this Sequence Number is per SCTP stream, the loss
        for the Data Records sent in that stream can be calculated in
        case of partially-reliable export.  If the SCTP stream only
        contains Data Records from a single Template ID, the Data
        Records for that Template ID can be calculated.
     
        If the Collecting Process receives a Template Withdrawal Message
        on a different stream than the one on which the Template ID is
        used, then the Collecting Process MUST reset the association and
        SHOULD log an error message.
     
        The following sentence from [RFC5101] is not applicable in this
        specification:
     
           "The Collecting Process normally receives Template Records
           from the Exporting Process before receiving Data Records.
           The Data Records are then decoded and stored by the
           Collector.  If the Template Records have not been received at
           the time Data Records are received, the Collecting Process
           MAY store the Data Records for a short period of time and
           decode them after the Template Records are received."
     
     
     5. Examples
     
        Figure 1 shows an example where the stream 10 carries a Template
        with the Template ID 256 transmitted with full reliability (FR),
        together with associated Data Records transmitted with partial
        reliability (PR).  Note that, because all IPFIX Messages are
     
     
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        sent in order within a stream, the Template 256 will always be
        processed before the Data Records by the Collecting Process.
        Therefore, the Collecting Process job is simplified.
        Furthermore, the Data Record loss for the Template 256 can
        easily be calculated on the Collecting Process.
     
                      +--------+       +---------+   +----------+
                      |        |       |         |   |          |
        stream 10 ----| Data   | . . . |  Data   |---| Template |--->
                      |   256  |       |    256  |   |     256  |
                      |      PR|       |       PR|   |        FR|
                      +--------+       +---------+   +----------+
                                     Figure 1
     
        If an Options Template is necessary to understand the content of
        a Data Record (i.e. the scope in the Options Template Record is
        an Information Element contained in the Data Record), the
        Options Template Record may be sent in the same stream, as
        displayed in figure 2.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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                         +--------+   +--------+     +----------+
                         |        |   |        |     |          |
        stream 20 ... ---| Data   |...| Data   |-----| Template |---
                         |   258  |   |   258  |     |     258  |
                         |      PR|   |      PR|     |        FR|
                         +--------+   +--------+     +----------+
     
                                +--------+       +----------+
                                |        |       | Options  |
                          ...---| Data   |-------| Template |------>
                                |   257  |       |     257  |
                                |      FR|       |        FR|
                                +--------+       +----------+
                                     Figure 2
     
        Figure 2 shows an example where stream 20 carries an Options
        Template with Template ID 257 transmitted with full reliability
        (FR), an associated Data Record transmitted with full
        reliability (FR), a Template with Template ID 258 transmitted
        with full reliability (FR), and associated Data Records
        transmitted with partial reliability (PR).  In this example the
        Option Template Record contains information required to decode
        the latter Data Records, such as Common Properties information
        [IPFIX-RED-RED]. So it makes sense to export the Data Sets 257
        reliably.  If some Data Record loss is observed from the
        Sequence Number , the loss can only stem from the Data Sets with
        the Template ID 258, as these are the only Sets not exported
        reliably.  Therefore, the calculation of loss per Template ID
        258 is possible.
     
        Note that, because all IPFIX Message must be sent in order
        within a stream, the Options Template 257 will always arrive
        before its associated Data Records, and that the Template 259
        will always arrive before the its associated Data Records.
     
        Figure 3 show an example where stream 30 carries an Template
        with Template ID 259 transmitted with full reliability (FR), an
        associated Data Record transmitted with partial reliability
        (PR), a Template Withdrawal Message, followed by a redefinition
        of the Template ID 259, and finally the new definition of Data
        Record transmitted with partial reliability. The Template
        Withdrawal Message and the new definition of the Template ID 259
        are sent immediately, without waiting for the Template Reuse
        Delay.
     
     
     
     
     
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                         +--------+   +----------+     +----------+
                         |        |   |          |     | Template |
        stream 30 ... ---| Data   |...| Template |-----| Withdraw.|---
                         |   259  |   |   259    |     |    259   |
                         |      PR|   |        FR|     |        FR|
                         +--------+   +----------+     +----------+
     
                                +--------+       +----------+
                                |        |       |          |
                          ...---| Data   |-------| Template |------>
                                |   259  |       |     259  |
                                |      PR|       |        FR|
                                +--------+       +----------+
     
                                     Figure 3
     
     6. IANA Considerations
     
        This document has no actions for IANA.
     
     
     7. Security Considerations
     
     
        The same security considerations as for the IPFIX Protocol
        [RFC5101] apply.
     
     8. References
     
     8.1. Normative References
     
        [RFC2119] S. Bradner, Key words for use in RFCs to Indicate
                Requirement Levels, BCP 14, RFC 2119, March 1997
     
        [RFC3758] Stewart, R., Ramalho, M, Xie, Q., Tuexen, M., Conrad,
                P., "Stream Control Transmission Protocol (SCTP),
                Partial Reliability Extension", May 2004
     
        [RFC4960] Stewart, R., Ed., "Stream Control Transmission
                Protocol", RFC 4960, September 2007.
     
        [RFC5101] Claise, B., Ed., "Specification of the IP Flow
                Information Export (IPFIX) Protocol for the Exchange of
                IP Traffic Flow Information", RFC 5101, January 2008.
     
     
     
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        [PSAMP-TECH] T. Zseby, M. Molina, N. Duffield, S. Niccolini, F.
                Raspall, "Sampling and Filtering Techniques for IP
                Packet Selection" draft-ietf-psamp-sample-tech-10.txt,
                Internet-Draft work in progress, June 2007
     
        [SCTP-RESET] Stewart, R., Lei, P., Tuexen, M, "Stream Control
                Transmission Protocol (SCTP) Stream Reset", draft-
                stewart-sctpstrrst-05.txt, Internet-Draft work in
                progress, June 2007
     
     8.2. Informative References
     
     
        [RFC3917] Quittek, J., Zseby, T., Claise, B. Zander, S,
                Requirements for IP Flow Information Export, RFC 3917,
                October 2004
     
        [IPFIX-ARCH] Sadasivan, G., Brownlee, N., Claise, B., Quittek,
                J., "Architecture Model for IP Flow Information Export"
                draft-ietf-ipfix-architecture-12, Internet-Draft work
                in progress, September 2006
     
        [IPFIX-AS] Zseby, T., Boschi, E., Brownlee, N., Claise, B.,
                "IPFIX Applicability", draft-ietf-ipfix-as-12.txt,
                Internet-Draft work in progress, February 2007
     
        [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and
                J. Meyer, "Information Model for IP Flow Information
                Export", RFC 5102, January 2008.
     
     
        [PSAMP-INFO] T. Dietz, F. Dressler, G. Carle, B. Claise,
                "Information Model for Packet Sampling Exports", draft-
                ietf-psamp-info-07.txt, Internet-Draft work in
                progress, October 2007
     
        [PSAMP-PROTO] Claise, B., Quittek, J., and A. Johnson, "Packet
                Sampling (PSAMP) Protocol Specifications", draft-ietf-
                psamp-protocol-09, Internet-Draft work in progress,
                December 2007.
     
        [PSAMP-FMWK] D. Chiou, B. Claise, N. Duffield, A. Greenberg, M.
                Grossglauser, P. Marimuthu, J. Rexford, G. Sadasivan,
                "A Framework for Passive Packet Measurement" draft-
                ietf-psamp-framework-12.txt, Internet-Draft work in
                progress, June 2007
     
     
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        [IPFIX-RED-RED] Boschi, E., Mark, L., Claise, B. "Reducing
                Redundancy in IPFIX and PSAMP Reports", Internet-Draft
                work in progress, draft-ietf-ipfix-reducing-redundancy-
                04.txt, May 2007
     
        [PSAMP-MIB] Dietz, T., Claise, B. "Definitions of Managed
                Objects for Packet Sampling", Internet-Draft work in
                progress, June 2006
     
     
     9. Acknowledgements
     
        The authors would like to thank Brian Trammell for expert
        feedback, Randall Stewart and Peter Lei for their SCTP-related
        feedback.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     10. Author's Addresses
     
        Benoit Claise
        Cisco Systems Inc.
        De Kleetlaan 6a b1
        Diegem 1813
        Belgium
     
        Phone: +32 2 704 5622
        Email: bclaise@cisco.com
     
     
        Paul Aitken
        Cisco Systems (Scotland) Ltd.
        96 Commercial Quay
        Commercial Street
        Edinburgh, EH6 6LX, United Kingdom
     
        Phone: +44 131 561 3616
        Email: paitken@cisco.com
     
     
        Andrew Johnson
        Cisco Systems (Scotland) Ltd.
        96 Commercial Quay
        Commercial Street
        Edinburgh, EH6 6LX, United Kingdom
     
        Phone: +44 131 561 3641
        Email: andrjohn@cisco.com
     
     
        Gerhard Muenz
        University of Tuebingen
        Computer Networks and Internet
        Sand 13
        Tuebingen  D-72076
        DE
     
        Phone: +49 7071 29-70534
        Email: muenz@informatik.uni-tuebingen.de
        URI:   http://net.informatik.uni-tuebingen.de/~muenz
     
     
     
     
     
     
     
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     11. Intellectual Property Statement
     
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