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   IPFIX working group
   Internet Draft                               EDITOR:      B. Claise
   draft-ietf-ipfix-protocol-07.txt                       Cisco Systems
   Expires: June 2005                                     December 2004





                       IPFIX Protocol Specification



 Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of RFC 3668.

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.  Internet-Drafts are draft documents valid for a maximum of
   six months and may be updated, replaced, or obsolete by other
   documents at any time.  It is inappropriate to use Internet-Drafts
   as reference material or to cite them other than as "work in
   progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt
   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

 Abstract

   This document specifies the IPFIX protocol that provides network
   operators with access to IP flow information.  In order to export
   IP flow information to the IPFIX collecting process, a common method
   of representing the flow data and a standard means of communicating
   them from an exporter to a collector is required.  This document
   describes how the IPFIX flow record data, options record data and



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   templates are carried over a congestion-aware transport protocol
   from an IPFIX exporting process to an IPFIX collecting process.

 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.

 Table of Contents

     1. Points of Discussion.........................................4
     2. Introduction.................................................5
      2.1 IPFIX Documents Overview...................................6
     3. Terminology..................................................6
      3.1 Terminology Summary Table.................................11
     4. Criteria for Flow Expiration and Export.....................12
      4.1 Flow Expiration...........................................12
      4.2 Flow Export...............................................12
     5. Message Format..............................................13
     6. IPFIX Message Format........................................15
      6.1 Header Format.............................................15
      6.2 Field Type Format.........................................16
      6.3 Template Set Format.......................................17
      6.4 Data Set Format...........................................19
      6.5 Options Template Set......................................21
     6.5.1   Scope..................................................21
     6.5.2   Options Template Set Format............................22
     6.5.3   Options Data Record Format.............................24
     7. Specific Reporting Requirements.............................26
      7.1 The Metering Process Statistics Option Template...........26
      7.2 The Metering Process Reliability Statistics Option Template27
      7.3 The Exporting Process Reliability Statistics Option Template28
      7.4 The Flow Keys Option Template.............................28
     8. "Export Time" Computation and Flow Record Time..............29
      8.1 Microsecond Precision.....................................29
      8.2 Millisecond Precision.....................................30
      8.3 Nanosecond Precision......................................31
      8.4 Multiple Precisions.......................................31
     9. Linkage with the Information Model..........................31
      9.1 Reduced Size Encoding of Integer Types....................31
     10. Variable Length Information Element........................32
     11. Template Management........................................33
     12. The Collecting Process's Side..............................36
     13. Transport Protocol.........................................38
      13.1 Transport Compliance and Transport Usage.................38
      13.2 TCP......................................................39
     13.2.1  Congestion Avoidance...................................39


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     13.2.2  Reliability............................................39
     13.2.3  MTU....................................................39
     13.2.4  Exporting Process......................................39
     13.2.4.1 Connection Establishment..............................39
     13.2.4.2 Connection Release....................................40
     13.2.4.3 IPFIX Message Encoding................................40
     13.2.5  Template Management....................................40
     13.2.6  Fail-over..............................................41
      13.3 SCTP.....................................................41
     13.3.1  Congestion Avoidance...................................41
     13.3.2  Reliability............................................41
     13.3.3  MTU....................................................42
     13.3.4  Exporting Process......................................42
     13.3.4.1 Association Establishment.............................42
     13.3.4.2 Association Shutdown..................................42
     13.3.4.3 Source ID.............................................43
     13.3.4.4 Stream................................................43
     13.3.4.5 Template Management...................................44
     13.3.5  Collecting Process.....................................44
     13.3.6  Failover...............................................44
      13.4 UDP......................................................44
     13.4.1  Congestion Avoidance...................................44
     13.4.2  Reliability............................................44
     13.4.3  MTU....................................................45
     13.4.4  Port Numbers...........................................45
     13.4.5  Exporting Process......................................45
     13.4.6  Template Management....................................45
     13.4.7  Collecting Process.....................................46
     13.4.8  Failover...............................................47
     14. Security Considerations....................................47
      14.1 IPsec Usage..............................................47
     14.1.1  Selectors..............................................48
     14.1.2  Mode...................................................48
     14.1.3  Key Management.........................................48
     14.1.4  Security Policy........................................48
     14.1.5  Authentication.........................................48
     14.1.6  Availability...........................................49
      14.2 TLS Usage................................................49
      14.3 Protection against DoS attacks...........................49
      14.4 When IPsec or TLS is not an option.......................50
      14.5 Logging an IPFIX Attack..................................50
     15. IANA Considerations........................................51
      15.1 Numbers used in the Protocol.............................51
      15.2 Numbers used in the Information Model....................51
     16. Examples...................................................52
      16.1 Message Header Example...................................52
      16.2 Template Set Examples....................................53
     16.2.1  Template Set using IETF specified Information Elements53



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     16.2.2  Template Set using Enterprise Specific Information
     Elements 53
      16.3 Data Set Example.........................................54
      16.4 Options Template Set Examples............................55
     16.4.1  Options Template Set using IETF specified Information
     Elements 55
     16.4.2  Options Template Set using Enterprise Specific
     Information Elements...........................................56
     16.4.3  Options Template Set using an Enterprise Specific scope57
      16.5 Data Set with Options Data Records Example...............57
     17. References.................................................58
      17.1 Normative References.....................................58
      17.2 Informative References...................................59
     18. Acknowledgments............................................60

 1.     Points of Discussion

   This section covers the open issues, still to be resolved/updated in
   this draft.  Note that the issues starting with PROTO-31 have been
   added to this draft version.

   PROTO-23: Finalize the time details. The time-related Information
   Elements are not defined in [IPFIX-INFO]. We agree that the
   definition of timer semantics should be moved to the info model
   document (see the http://ipfix.doit.wisc.edu/archive/2588.html email
   thread). Now we need:
   - to insert some new text in the section 9 of this document
   - to insert the timing Information Element in [IFPIX-INFO]
   Note: see http://ipfix.doit.wisc.edu/archive/2580.html for a way to
   improve the timing-related Information Elements.

   PROTO-30: review RFC 3917, to see if we miss any requirements

   PROTO-34: Need a security expert to review the security section:
          - [TBD] in the security section
          - [EDITOR NOTE: the security section may need be adapted to
          the revised transport section], [XXX-REFERENCE]
          - [XXX-SCTP-BLIND-SPOOFING-REFERENCE] not defined
          - TCP Security
          1. Handshake: should we introduce a handshake sequence at the
          start of the connection? A simple ASCII-based handshake could
          be used to request TLS.
          2. It would make sense to add TLS support even in the absence
          of a handshake. It would be the responsibility of the



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          collector (connection initiator) to know whether TLS setup is
          required.

   PROTO-38: [IPFIX-INFO] consistency issue:
          - the ipfixOption, time, droppedFUPacketCount,
          droppedFUByteCount, droppedFlows, keyList,
          timeFirstFUDropped, timeLastFUDropped, droppedFAPacketCount,
          droppedFAByteCount, timeFirstFADropped, timeLastFADropped,
          and Exporter ID, Source ID Information Elements are not used
          in this document but not yet specified in [IPFIX-INFO].
          - Review the Options Template example once the Source ID is
          defined as an information element (currently the ID 141 is
          used)
   PROTO-44: UDP, TCP, and SCTP ports XXXX should be replaced once
   assigned by IANA. Proposal: 4739

   PROTO-46: TCP section update, waiting text for Simon Leinen. See the
   thread starting with http://ipfix.doit.wisc.edu/archive/2569.html

   PROTO-47: Some ææEDITORÆS NOTEÆÆ in the draft.

   PROTO-48: Should the ææsequence numberÆÆ be improved to contains the
   number of flow records, like proposed in
   http://ipfix.doit.wisc.edu/archive/2587.html?


 2.     Introduction

   A data network with IP traffic, primarily consists of IP Flows
   passing through the network elements of the network.  It is often
   interesting, useful or even a requirement to have access to
   information about these flows that pass through the network elements
   for administrative or other purposes.  The IPFIX collecting process
   should be able to receive the flow information passing through
   multiple network elements within the data network.  This requires
   uniformity in the method of representing the flow information and
   the means of communicating the flows from the network elements to
   the collection point.  This document specifies the protocol to
   achieve these aforementioned requirements.  This document specifies
   in detail the representation of different flows, the additional data
   required for flow interpretation, packet format, transport
   mechanisms used, security concerns, etc.




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 2.1      IPFIX Documents Overview

   The IPFIX protocol 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 [IPFIX-ARCH], per the requirements defined in
   [IPFIX-REQ].  This document specifies how IPFIX flow record data,
   options record data, and templates are carried via a congestion-
   aware transport protocol from IPFIX exporting process to IPFIX
   collecting process.  IPFIX has a formal description of IPFIX
   information elements (fields), their name, type and additional
   semantic information, as specified in [IPFIX-INFO].  Finally [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.

 3.    Terminology

   The definitions of the basic terms like IP Traffic Flow, Exporting
   Process, Collecting Process, Observation Points, etc. are
   semantically identical with that found in the IPFIX requirements
   document [IPFIX-REQ].  Some of the terms have been expanded for more
   clarity when defining the protocol.  Additional terms required for
   the protocol has also been defined.  Definitions in this document
   and in [IPFIX-ARCH] are equivalent, except that definitions which
   are only relevant to the IPFIX protocol only appear here.  Should
   there be any apparent discrepancy in definitions between these two
   documents, the definitions defined in this document take precedence.

   The terminology summary table in Section 3.1 gives a quick overview
   of the relationships between some of the different terms defined.

 Observation Point

   An Observation Point is a location in the network where IP packets
   can be observed.  Examples include: a line to which a probe is
   attached, a shared medium, such as an Ethernet-based LAN, a single
   port of a router, or a set of interfaces (physical or logical) of a
   router.

   Note that one Observation Point may be a superset of several
   other Observation Points.  For example, one Observation Point can be



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   an entire line card.  This would be the superset of the
   individual Observation Points at the line card's interfaces.

 Observation Domain

   An Observation Domain is the largest set of Observation Points for
   which Flow information can be aggregated by a Metering Process.
   Each Observation Domain presents itself using a unique ID to the
   Collecting Process to identify the IPFIX Messages it generates.  For
   example, a router line card may be an observation domain if it is
   composed of several interfaces: each of which is  an Observation
   Point.  Every Observation Point is associated with an Observation
   Domain.

 IP Traffic Flow or Flow

   There are several definitions of the term 'flow' being used by the
   Internet community.  Within the context of IPFIX we use the
   following definition:

   A Flow is defined as a set of IP packets passing an Observation
   Point in the network during a certain time interval.  All packets
   belonging to a particular Flow have a set of common properties.
   Each property is defined as the result of applying a function to the
   values of:

      1. one or more packet header field (e.g. destination IP address),
      transport header field (e.g. destination port number), or
      application header field (e.g. RTP header fields [RFC1889])

      2. one or more characteristics of the packet itself (e.g. number
      of MPLS labels, etc...)

      3. one or more of fields derived from packet treatment (e.g. next
      hop IP address, the output interface, etc...)

   A packet is defined to belong to a Flow if it completely satisfies
   all the defined properties of the Flow.

   This definition covers the range from a Flow containing all packets
   observed at a network interface to a Flow consisting of just a
   single packet between two applications.  It includes packets
   selected by a sampling mechanism.


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 Flow Key

   Each of the fields which

   1.  Belong to the packet header (e.g. destination IP address)

   2.  Are a property of the packet itself (e.g. packet length)

   3.  Are derived from packet treatment (e.g. AS number)

   and which are used to define a Flow are termed Flow Keys.

 Flow Record

   A Flow Record contains information about a specific Flow that was
   observed at an Observation Point.  A Flow Record contains measured
   properties of the Flow (e.g. the total number of bytes of all
   packets of the Flow) and usually characteristic properties of the
   Flow (e.g. source IP address).

 Metering Process

   The Metering Process generates Flow Records.  Input to the process
   are packet headers observed at an Observation Point and packet
   treatment at the Observation Point (for example the selected output
   interface).

   The Metering Process consists of a set of functions that includes
   packet header capturing, timestamping, sampling, classifying, and
   maintaining Flow Records.

   The maintenance of Flow Records may include creating new records,
   updating existing ones, computing Flow statistics, deriving further
   Flow properties, detecting Flow expiration, passing Flow Records to
   the Exporting Process, and deleting Flow Records.

 Exporting Process

   The Exporting Process sends Flow Records to one or more Collecting
   Processes.  The Flow Records are generated by one or more Metering
   Processes.



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 IPFIX Device

   An IPFIX Device hosts at least one Observation Point, a Metering
   Process and an Exporting Process.  Typically, corresponding
   Observation Point(s), Metering Process(es) and Exporting Process(es)
   are co-located at such a device, for example at a router.

 Exporter

   A device which hosts one or more Exporting Processes is termed an
   Exporter.

 Collecting Process

   A Collecting Process receives Flow Records from one or more
   Exporting Processes.  The Collecting Process might process or store
   received Flow Records, but such actions are out of scope for this
   document.

 Collector

   A device which hosts one or more Collecting Processes is termed a
   Collector.

 Template

   Template is an ordered sequence of pairs (<type,length>), used to
   completely identify the structure and semantics of a particular
   information that needs to be communicated from the IPFIX Device to
   the Collector.  Each Template is uniquely identifiable by means of a
   Template ID.

 IPFIX Message

   An IPFIX Message is a message originating at the Exporting Process
   that carries the IPFIX records of this Exporting Process and whose
   destination is the Collecting Process.  An IPFIX Message is
   encapsulated within a transport layer.

 Message Header






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   The Message Header is the first part of an IPFIX Message, which
   provides basic information about the message such as the IPFIX
   version, length of the message, message sequence number, etc.

 Template Record

   A Template Record defines the structure and interpretation of fields
   in a Flow Data Record.

 Flow Data Record

   A Flow Data Record is a data record that contains values of the Flow
   parameters corresponding to a Template Record.

 Options Template Record

   An Options Template Record defines the structure and interpretation
   of fields in an Options Data Record, including defining how to scope
   the applicability of the Options Data Record.

 Options Data Record
   The Options Data Record is a data record that contains values and
   scope information of the Flow measurement parameters, corresponding
   to an Options Template Record.

 Set

   Set is a generic term for a collection of records that have a
   similar structure.  In an IPFIX Message, one or more Sets follow the
   Message Header.

   There are three different types of Sets: Template Set, Options
   Template Set, and Data Set.

 Template Set

   A Template Set is a collection of one or more Template Records that
   have been grouped together in an IPFIX Message.

 Options Template Set





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   An Options Template Set is a collection of one or more Options
   Template Records that have been grouped together in an IPFIX
   Message.

 Data Set

   A Data Set is one or more records, of the same type, that are
   grouped together in an IPFIX Message.  Each record is either a Flow
   Data Record or an Options Data Record previously defined by a
   Template Record or an Options Template Record.

 Information Element

   An Information Element is a protocol and encoding independent
   description of an attribute which may appear in an IPFIX Flow
   Record.  The IPFIX information model [IPFIX-INFO] defines the base
   set of Information Elements for IPFIX.  The type associated with an
   Information Element indicates constraints on what it may contain and
   also determine the valid encoding mechanisms for use in IPFIX.

 3.1      Terminology Summary Table

    +------------------+---------------------------------------------+
    |                  |                    Contents                 |
    |                  +--------------------+------------------------+
    |       Set        | Template  Record   |      data record       |
    +------------------+--------------------+------------------------+
    |                  |                    |  Flow Data Record(s)   |
    |   Data Set       |          /         |          or            |
    |                  |                    | Options Data Record(s) |
    +------------------+--------------------+------------------------+
    |   Template Set   | Template Record(s) |           /            |
    +------------------+--------------------+------------------------+
    | Options Template | Options Template   |           /            |
    |       Set        | Record(s)          |                        |
    +------------------+--------------------+------------------------+

      Figure A: Terminology Summary Table

   A Data Set is composed of an Options Data Record(s) or Flow Data
   Record(s).  No Template Record is included.  A Template Record
   defines the Flow Data Record, and an Options Template Record defines
   the Options Data Record.


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   A Template Set is composed of Template Record(s).  No Flow or
   Options Data Record is included.

   An Options Template Set is composed of Options Template Record(s).
   No Flow or Options Data Record is included.

 4.     Criteria for Flow Expiration and Export

 4.1      Flow Expiration

   A Flow is considered as expired under the following conditions:

   1. If the Metering Process can deduce the end of a Flow, that
   Flow Record should be exported when the end of the Flow is
   detected.  For example, a Flow generated by TCP [TCP] traffic where
   the FIN or RST bits indicate the end of the Flow Record.

   2. If no packets belonging to the Flow have been observed for a
   certain period of time.  This time period should be configurable at
   the Metering Process, with a minimum value of 0 seconds for
   immediate expiration.  Note that a zero timeout would report a Flow
   as a sequence of single-packet Flows.

   3. If the IPFIX Device experiences resource constraints, a Flow
   Record may be prematurely expired (e.g. lack of memory to store Flow
   Records).

   4. For long-running Flows, the Metering Process should expire the
   Flow Record on a regular basis or based on some expiration policy.
   This periodicity or expiration policy should be configurable at the
   Metering Process. When the Record of a long-running Flow is expired,
   that Flow Record may still be maintained by the Metering Process so
   that, for further observed packets of the same Flow Record, the
   Metering Process does not need to create a new Flow Record.

 4.2      Flow Export

   The Exporting Process decides when and whether to export an expired
   Flow.  A Flow can be exported because it expired due to the reasons
   mentioned in Flow Expiration section.  For example: the Exporting
   Process exports a portion of the expired Flows every 'x' seconds.




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   For long-lasting Flows, the Exporting Process should export the Flow
   Records on a regular basis or based on some export policy.  This
   periodicity or export policy should be configurable at the Metering
   Process.

 5.     Message Format

   An IPFIX Message consists of a Message Header followed by one or
   more Sets.  The Sets can be any of the possible three types:
   Template, Data, or Options Template.

   The format of the IPFIX Message is shown in Figure B.

   +--------+-------------------------------------------+
   |        | +----------+ +---------+ +----------+     |
   |Message | | Template | |  Data   | | Options  |     |
   | Header | |   Set    | |   Set   | | Template | ... |
   |        | |          | |         | |    Set   |     |
   |        | +----------+ +---------+ +----------+     |
   +--------+-------------------------------------------+

      Figure B: IPFIX Message format

   A Set ID is used to distinguish the different types of Sets.  Set
   IDs lower than 256 are reserved for special Sets, such as the
   Template Set (ID 2) and the Options Template Set (ID 3).  The Data
   Sets have a Set ID greater than 255.  The Set ID value of 0 and 1
   are not used for historical reasons [NETFLOW9].

   The format of the Template, Data, and Options Template Sets will be
   discussed later in this document.  The Exporter MUST code all binary
   integers of the Message Header and the different Sets in network
   byte order (also known as the big-endian byte ordering).

   Following are some examples of IPFIX Messages:

   1. An IPFIX Message consisting of interleaved Template, Data, and
   Options Template Sets-A newly created Template is exported as soon
   as possible.  So if there is already an IPFIX Message with a Data
   Set that is being prepared for export, the Template and Option Sets
   are also interleaved with this information, subject to availability
   of space.



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   +--------+--------------------------------------------------------+
   |        | +----------+ +---------+     +-----------+ +---------+ |
   |Message | | Template | | Data    |     | Options   | | Data    | |
   | Header | | Set      | | Set     | ... | Template  | | Set     | |
   |        | |          | |         |     | Set       | |         | |
   |        | +----------+ +---------+     +-----------+ +---------+ |
   +--------+--------------------------------------------------------+

      Figure C: IPFIX Message example 1

   2. An IPFIX Message consisting entirely of Data Sets-After the
   appropriate Template Records have been defined and transmitted to
   the Collecting Process, the majority of IPFIX Messages consist
   solely of Data Sets.

   +--------+----------------------------------------------+
   |        | +---------+     +---------+      +---------+ |
   |Message | | Data    | ... | Data    | ...  | Data    | |
   | Header | | Set     | ... | Set     | ...  | Set     | |
   |        | +---------+     +---------+      +---------+ |
   +--------+----------------------------------------------+

      Figure D: IPFIX Message example 2

   3. An IPFIX Message consisting entirely of Template and Options
   Template Sets-When UDP is used as the transport protocol, Templates
   Sets and Option Template Sets MUST be sent periodically to help
   ensure that the Collecting Process has the correct Template Records
   and Options Template Records when the corresponding Flow Data
   Records are received.

   +--------+-------------------------------------------------+
   |        | +----------+     +----------+      +----------+ |
   |Message | | Template |     | Template |      | Options  | |
   | Header | | Set      | ... | Set      | ...  | Template | |
   |        | |          |     |          |      | Set      | |
   |        | +----------+     +----------+      +----------+ |
   +--------+-------------------------------------------------+

      Figure E: IPFIX Message example 3





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 6.     IPFIX Message Format

 6.1      Header Format

   The format of the IPFIX Message Header format is shown in Figure F.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Version Number          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Export Time                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Sequence Number                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Source ID                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure F: IPFIX Message Header format

   Message Header Field Descriptions

   Version
           Version of Flow Record format exported in this message.  The
           value of this field is 0x000a for the current version.

   Length
           Total Length is the length of the IPFIX Message, measured in
           octets, including message Header and Set(s).

   Export Time
           Time in seconds since 0000 UTC 1970, at which the IPFIX
           Message Header leaves the Exporter.

   Sequence Number
           Incremental sequence counter modulo 2exp32  of all IPFIX
           Messages sent on this stream from the current Observation
           Domain by the Exporting Process. This value SHOULD be used
           by the Collecting Process to identify whether any IPFIX
           Messages have been missed.

   Source ID




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           A 32-bit value that identifies the Exporter Process
           Observation Domain.  Collecting Process SHOULD use the
           combination of the source IP address and the Source ID field
           to separate different export streams originating from the
           same Exporting Process.

 6.2      Field Type Format

   Vendors need the ability to define proprietary Information Elements,
   because, for example, they are delivering pre-standards product, or
   the Information Element is in some way commercially sensitive.  This
   section describes the Field Type format for both IETF specified
   Information Elements [IPFIX-INFO] and Enterprise Specific
   Information Elements, both the Template Set and the Option Template
   Set.

   The Field Ids used to identify Information Elements are represented
   by the Field Type.  When the Enterprise Field Type bit is set to 0,
   the corresponding Field Type will report an IETF specified
   Information Elements.  When the Enterprise Field Type bit is set to
   1, the corresponding Field Type will report an Enterprise Specific
   Information Element.  An example of this is shown in section 16.


   The Field Type format is shown in Figure G.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |E|      Field Type             |        Field Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Enterprise Number                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure G: Field Type format

        Where:

       E
          Enterprise Field Type.  This is the first bit of the Field
          Type. If this bit is zero, the Field Type identifies an IETF
          specified Information Element, and the four octet Enterprise
          Number field MUST NOT be present.  If this bit is one, the


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          Field Type identifies an Enterprise Specific Information
          Element, and the Enterprise Number filed MUST be present.

      Field Type
         A numeric value that represents the type of the field.  Refer
         to [IPFIX-INFO].

      Field Length
         The length of the corresponding Field Type, in bytes.  Refer
         to [IPFIX-INFO].

      Enterprise Number
         IANA enterprise number [PEN] of the authority defining the
         Field Type in this Template Record.

 6.3      Template Set Format

   One of the essential elements in the IPFIX format is the Template
   Set.  Templates greatly enhance the flexibility of the Flow Record
   format because they allow the Collecting Process to process Flow
   Records without necessarily knowing the interpretation of all the
   data in the Flow Record.  A Template Set MAY exclusively contain
   IETF defined Field Types.  A Template Set MAY contain Enterprise
   Specific Information Elements from one or more vendors.

   The format of the Template Set is shown in Figure H.

       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               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID 256          |         Field Count 1         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Type 1.1          |        Field Length 1.1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  1.1                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Type 1.2          |        Field Length 1.2       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Type 1.N          |        Field Length 1.N       |


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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  1.N                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID 257          |         Field Count 2         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Type 2.1          |        Field Length 2.1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Type 2.2          |        Field Length 2.2       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  2.2                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Type 2.M          |        Field Length 2.M       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  2.M                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Padding (opt)                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure H: Template Set Format

   Field Types 1.2 and 2.1 are defined by the IETF (bit 0 = 0) and
   therefore do not need and Enterprise Number to identify them.

   The Template Set Field Definitions are as follows:

     Set ID
           Set ID value of 2 is reserved for the Template Set.

     Length
           Total length of this Set.  Because an individual Template
           Set MAY contain multiple Template Records, the Length value
           MUST be used to determine the position of the next Set
           record, which could be any type of Set.  Length is the sum
           of the lengths of the Set ID, the Length itself, and all
           Template Records within this Set.

     Template ID
           Each of the newly generated Template Records is given a
           unique Template ID.  This uniqueness is local to the
           Observation Domain that generated the Template ID.



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           Template IDs 0-255 are reserved for Template Sets, Options
           Sets, and other reserved Sets yet to be created.  Template
           IDs of Data Sets are numbered from 256 to 65535.

     Field Count
           Number of fields in this Template Record.  Because a
           Template Set usually contains multiple Template Records,
           this field allows the Collecting Process to determine the
           end of the current Template Record and the start of the
           next.

     Field Type
           A numeric value that represents the type of the field.
           Refer to [IPFIX-INFO].

     Field Length
           The length of the corresponding Field Type, in bytes.  Refer
           to [IPFIX-INFO].

      Enterprise Number
           IANA enterprise number [PEN] of the authority defining the
           Field Type.

      Padding
           The Exporting Process MAY insert some padding bytes, so that
           the subsequent Set starts at an aligned boundary.  Padding
           MUST be composed of zero (0) bytes.  The padding length MUST
           be shorter than any allowable Template Record in this
           Template Set.  It is important to note that the Length field
           includes the padding bytes.  Because Template Sets are
           always 4-byte aligned by definition padding is only needed
           in case of other alignments e.g. on 8-byte boundaries.

   The Set ID value of 0 and 1 are not used for historical reasons
   [NETFLOW9].

 6.4      Data Set Format

   The format of the Data Set is shown in Figure I.

    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 = Template ID        |          Length               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 1 - Field Value 1    |   Record 1 - Field Value 2    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 1 - Field Value 3    |             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 2 - Field Value 1    |   Record 2 - Field Value 2    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 2 - Field Value 3    |             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 3 - Field Value 1    |             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |        Padding (opt)          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure I: Data Set Format

   Note that not all Field Values do necessarily have a length of 16
   bit.

   Data Set Field Descriptions are as follows:

   Set ID = Template ID
           Each Data Set is associated with a Set ID.  The Set ID maps
           to a (previously generated) Template ID.  The Collecting
           Process MUST use the Set ID to find the corresponding
           Template Record and decode the Flow Records from the Set.

   Length
           The length of this Set.
           Length is the sum total of lengths of Set ID, Length itself,
           all Flow Records within this Set, and the padding bytes, if
           any.

   Record N - Field Value M
           The remainder of the Data Set is a collection of Flow Data
           Record(s), each containing a set of Field Types and values.
           The Type and Length of the fields have been previously
           defined in the Template Record referenced by the Set ID or
           Template ID.

   Padding



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           The Exporting Process MAY insert some padding bytes, so that
           the subsequent Set starts at an aligned boundary.  Padding
           MUST be composed of zero (0) bytes.  The padding length MUST
           be shorter than any allowable Flow Data Record in this Data
           Set.  It is important to note that the Length field includes
           the padding bytes.

   Interpretation of the Data Set format can be done only if the
   Template Set corresponding to the Template ID is available at the
   Collecting Process.

 6.5      Options Template Set

   The Options Template Record (and its corresponding Options Data
   Record) is used to supply information about the Metering Process
   configuration or Metering Process specific data, rather than
   supplying information about IP Flows.

   For example, the Options Template Set can report the sample rate of
   a specific interface, if sampling is supported, along with the
   sampling method used.

 6.5.1   Scope

   The Options Template Set gives the Exporter the ability to provide
   additional information to the Collector which would not be possible
   with only Flow Records. The scope, which is only available in the
   Options Template Set, gives the context of the reported Information
   Elements.  One Options Template Set example is the "Metering Process
   statistics", which reports the statistics for the Observation
   Domain, which is defined as the scope.  Another example is the
   "Template configuration", which reports the configuration sampling
   parameter(s) for the template, which is defined as the scope.

   Multiple scope fields MAY be present in the Options Template Set, in
   which, the composite scope is the combination of the scopes. For
   example, if the two scopes are defined as "cache" and "template",
   the combined scope is this template in this cache.  The order of the
   scope, as defined in the Options Template Set, is in this case
   irrelevant. However, if the order of the scopes fields in the Option
   Template Set is relevant, the order of the scope fields MUST be
   used.  For example, if the first scope defines the filtering
   function, while the second scope defines the sampling function, the


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   order of the scope is important. Applying first the sampling
   function, followed by the filtering function, would lead to
   potential different Flow Records than applying first the filtering
   function, followed by the filtering function.  In this case, the
   Collector deduces the function order by looking at the order of the
   scope in the Options Template Set.

   Finally, note that the scope length MAY NOT be zero.

 6.5.2   Options Template Set Format

   An Options Template MAY exclusively contain IETF defined Field
   Types.  An Options Template MAY contain Enterprise Specific
   Information Elements from multiple vendors.  An Options Template MAY
   contain IETF defined Field Types and Enterprise Specific Information
   Elements.

   The format of the Options Template Set is shown in Figure J.

       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 = 3           |          Length               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Template ID           |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Scope Field Count        |      Scope 1 Field Type       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope 1 Field Length      |      Scope 2 Field Type       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope 2 Field Length      |             ...               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            ...                |      Scope N Field Type       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope N Field Length      |   Scope N Entreprise Number ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ...  Scope N Enterprise Number   |      Option 1 Field Type      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Option 1 Field Length      |  Option 1 Entreprise Number ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ... Option 1 Enterprise Number   |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |       Option M Field Type     |


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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Option M Field Length     |         Padding (opt)         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure J: Option Template Set Format

   The Options Template Set Field Definitions are as follows:

   Set ID = 3
           A Set ID value of 3 is reserved for the Options Template.

   Length
           Total length of this Set, including the padding bytes, if
           any.  Each Options Template Set MAY contain multiple Options
           Template Records.  Thus, the Length value MUST be used to
           determine the position of the next Set record, which could
           be either a Template Set or Data Set.
           Length is the sum total of lengths of Set ID, the Length
           itself, and all Options Template Records within this Set
           Template ID.

   Template ID
           Template ID of this Options Template.  This value is greater
           than 255.

   Field Count
           Number of all fields in this Option Template Record,
           including the Scope Fields.  Because a Option Template Set
           usually contains multiple Template Records, this field
           allows the Collecting Process to determine the end of the
           current Option Template Record and the start of the next.

   Scope Field Count
           Number of scope fields in this Option Template Record.

   Scope Field Type
           A numeric value that represents the type of the field.
           Refer to [IPFIX-INFO].

   Scope Field Length
           The length (in bytes) of the Scope field, as it would appear
           in an Options Data Record.



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   Scope N Enterprise Number
           IANA enterprise number [PEN] of the authority defining
           Scope N Field Type. This is 4 bytes long.

   Option Field Type
           A numeric value that represents the type of field.  Refer to
           [IPFIX-INFO].

   Option Field Length
           The length of the corresponding Option Field Type, in bytes.
           Refer to [IPFIX-INFO].

    Option M Enterprise Number
           IANA enterprise number [PEN] of the authority defining the
           Option M Field Type. This is 4 bytes long.

   Padding
           The Exporting Process MAY insert some padding bytes, so that
           the subsequent Set starts at an aligned boundary.  Padding
           MUST be composed of zero (0) bytes.  The padding length MUST
           be shorter than any allowable Options Template Record in
           this Options Template Set.  It is important to note that the
           Length field includes the padding bytes.

   The Set ID value of 0 and 1 are not used for historical reasons
   [NETFLOW9].

 6.5.3   Options Data Record Format

   The Options Data Records are sent in Data Sets.

   The format of the Data Set, containing Options Data Records, is
   shown in Figure K.

    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 = Template ID     |          Length               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 1 - Scope 1 Value    |   Record 1 - Scope 2 Value    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |Record 1 - Option Field 1 Value|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


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   |Record 1 - Option Field 2 Value|             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 2 - Scope 1 Value    |   Record 2 - Scope 2 Value    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |Record 2 - Option Field 1 Value|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Record 2 - Option Field 2 Value|             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 3 - Scope 1 Value    |   Record 3 - Scope 2 Value    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |Record 3 - Option Field 1 Value|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Record 3 - Option Field 2 Value|             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |         Padding (opt)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure K: Data Set format, containing Options Data Records

   Options Data Records of the Data Set Field Descriptions

   Set ID = Template ID
           A Set ID precedes each group of Options Data Records within
           a Data Set.  The Set ID maps to a previously generated
           Template ID corresponding to this Options Template Record.
           The Collecting Process MUST use the Set ID to map the
           appropriate type and length to any field values that follow.

   Length
           The length of this Set.
           Length is the sum of the lengths of the Set ID, Length
           itself, all the Options Data Records within this Set, and
           the padding bytes, if any.

   Record N - Option Field M Value
           The remainder of the Data Set is a collection of Flow
           Records, each containing a set of Scope and Field Values.
           The type and length of the fields were previously defined in
           the Options Template Record referenced by the Set ID or
           Template ID.

   Padding



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           The Exporting Process MAY insert some padding bytes, so that
           the subsequent Set starts at an aligned boundary.  Padding
           MUST be composed of zero (0) bytes.  The padding length MUST
           be shorter than any allowable Options Data Record in this
           Data Set.  It is important to note that the Length field
           includes the padding bytes.

   The Data Set format can be interpreted only if the Options Template
   Set corresponding to the Template ID is available at the Collecting
   Process.

 7.     Specific Reporting Requirements

   Some specific Options Templates and Options Templates Records are
   necessary to provide extra information about the Flow Records and
   about the Metering Process.

   The ipfixOption Field [IPFIX-INFO], always included in these
   specific Options Templates, defines the type of information sent in
   the Option Template / Option Template Record pair.  For example, if
   the ipfixOption [IPFIX-INFO] value is METER_STATS, then the Option
   Template will specify information about the Metering Process
   statistics.

   The Option Template and Option Template Records defined in these
   sub-sections are not mandatory to implement as they impose some
   constraints about the Metering Process implementation: this document
   specifies the protocol to export the records, not the Metering
   Process implementation.  However, if the specific Option Templates
   are implemented, they should ideally be implemented as specified in
   these sub-sections.  In any case, if the ipfixOption Information
   Element is present, it MUST always be the first Information Element
   in the Option Template so that the Collector can quickly determine
   which specific Option Template Record is received.

   The minimum set of Information Elements is always specified in these
   Specific IPFIX Options Templates.  Nevertheless, extra Information
   Elements may be used in these specific Options Templates.

 7.1      The Metering Process Statistics Option Template






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   The Metering Process Statistics Option Template specifies the
   Metering Process Statistics. It contains the following Information
   Elements [IPFIX-INFO]:
        ipfixOption             The value is METERING_STATS
        exportedOctetCount      The number of all octets reported
                                by the Exporting Process to the
                                Collecting Process.
        exportedPacketCount     The number of all packets reported
                                by the exporting process to the
                                Collecting Process.
        exportedFlowCount       The number of all flows records
                                reported by the Exporting Process
                                to the Collecting Process.
        time                    The time at which the record was
                                generated

   The Exporting Process should export the Metering Process Statistics
   Option Template Record on a regular basis or based on some export
   policy.  This periodicity or export policy should be configurable.
   The Metering Process Statistics Option Template could be extended
   with other Information Elements.

   The Scope Field specified in the Metering Process Statistics Option
   Template Record is the Source ID.

 7.2      The Metering Process Reliability Statistics Option Template

   The Metering Process Reliability Option Template specifies
   information about lack of reliability in the Metering process.  It
   contains the following Information Elements [IPFIX-INFO]:

        ipfixOption             The value is METERING_RELIABILITY_STATS
        droppedFUPacketCount    Packets dropped by Metering Process
        droppedFUOctetCount     Bytes dropped by Metering Process
        timeFirstFUDropped      Time of the first packet dropped at the
                                Specified scope ID
        timeLastFUDropped       Time of the last packet dropped at the
                                Specified scope ID
        time                    The time at which the record was
                                generated

   The Exporting Process should export the Metering Process Reliability
   Statistics Option Template Record on a regular basis or based on


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   some export policy.  This periodicity or export policy should be
   configurable. The Metering Process Reliability Statistics Option
   Template could be extended with other Information Elements.

   The Scope Field specified in the Metering Process Reliability
   Statistics Option Template Record is the Source ID.

 7.3      The Exporting Process Reliability Statistics Option Template

   The Exporting Process Reliability Option Template specifies
   information about lack of reliability in the Exporting process.  It
   contains the following Information Elements [IPFIX-INFO]:

        ipfixOption             The value is
                                EXPORTING_RELIABILITY_STATS
        droppedFlows            Number of flow records not exported
                                (due to resources starvation at
                                Exporting Process or due to some
                                flow records export policies)
        droppedFAPacketCount    Packets in the dropped flows
        droppedFAByteCount      Bytes in the dropped flows
        timeFirstFADropped      Time of the first packet within the
                                dropped flows
        timeLastFADropped       Time of the last packet within the
                                dropped flows
        time                    The time at which the record was
                                generated

   The Exporting Process should export the Exporting Process
   Reliability Statistics Option Template Record on a regular basis or
   based on some export policy.  This periodicity or export policy
   should be configurable. The Exporting Process Reliability Statistics
   Option Template could be extended with other Information Elements.

   The Scope Field specified in the Exporter Reliability Statistics
   Option Template Record is the Exporter ID.

 7.4      The Flow Keys Option Template

   The Flow Keys Option Template specifies the flow keys used by the
   Metering Process for the Template ID definition. It contains the
   following Information Elements [IPFIX-INFO]:



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        ipfixOption             The value is FLOW_KEY
        keyList                 Bitmap with the positions of the flow
                                keys in the template
        time                    The time at which the record was
                                generated

   The Scope Field specified in the Flow Keys Option Template Record is
   the Template ID with which the flow keys are associated.

 8.     "Export Time" Computation and Flow Record Time

 8.1      Microsecond Precision

   For a Data Set with Flow Records requiring microsecond precision,
   the IPFIX Message Header "Export Time" field MUST be calculated so
   that each Flow Records flowStartUsec [IPFIX-INFO] and flowEndUsec
   [IPFIX-INFO] would contain a 32 bit signed microsecond offset from
   the "Export Time" base timestamp.  Hereafter some pseudo code to
   calculate the Export Time in one pass, which would return an
   absolute duration of 35 minutes for all Flow Records contained in
   the Data Set.  Flow Records MUST be exported in different IPFIX
   Message Header if the absolute durations can not fit in those 35
   minutes.

   //  pseudo code for microsecond offset in IPFIX encoded Flow
   Records.
   //

   struct flow{
      uint32  tv_sec;
      uint32  tv_usec;
      uint32  numbytes;
      ...  // other Information Elements...
   };

   struct flow flowtable [MAX_TABLE_SIZE];
   int lastflowindex = -1;

   writeflows() {
      if (lastflowindex < 0) return;
      // simply take the second field from the first available flow
      // and make this the base time for this collection of flows.
      uint32  base_sec = flowtable[0].tv_sec;



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      writeheaderToSocket(base_sec); // put 32-bit second value in
                                        header
      for (int i=0; i<=lastflowindex; i++){
         int32 offset = (flowtable[i].tv_sec - base_sec) * 1000000
                        + flowtable[i].tv_usec;
         writeint32ToSocket(offset);  // put the 32-bit time offset
                                         in the record.
         // write other Information Elements...
       }
   }

   A two pass approach calculation for the optimum (center) "Export
   Time" base timestamp would allow an absolute duration of 71 minutes
   for all Flow Records contained in the Data Set.  The two pass
   approach MAY be used.  The "Export Time" base timestamp calculation
   requires that at the IPFIX Message Header exporting time the
   Exporting Process MUST run down the list of Flow Records in the Data
   Set message and adjust the Flow start and Flow end timestamps.

 8.2      Millisecond Precision

   For a Data Set with Flow Records requiring a millisecond precision,
   the same principles as in section 9.1 "Microsecond Precision" will
   be used.

   The only difference will be that the Flow start and the Flow end
   SHOULD now be represented respectively by the flowStartMsec [IPFIX-
   INFO] and flowEndMsec [IPFIX-INFO].  As a consequence of the
   millisecond precision, the absolute duration of all Flow Records is
   now of about 49 days.  The Export header "Export Time" base time
   SHOULD be calculated with the algorithm described in the Section 9.1
   "Microsecond Precision".  In order to reduce the load on the
   Exporter, the Export header "Export Time" MAY be the time in seconds
   since 0000 UTC 1970 at which the IPFIX Message Header leaves the
   Exporter and not the calculated optimum value anymore as described
   in section 9.1 "Microsecond Precision".

   Alternatively, for a Data Set with Flow Records requiring a
   millisecond precision, the microsecond mechanism as described in
   section 9.1 MAY be used as such.  The Flow Record MAY use the
   flowStartUsec [IPFIX-INFO] and flowEndUsec [IPFIX-INFO] rounded at a
   millisecond precision.



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 8.3      Nanosecond Precision

   For a Data Set with Flow Records requiring a nanosecond precision,
   all Flow Records will contain Flow start flowStartNsec [IPFIX-INFO]
   and flowEndNsec [IPFIX-INFO].  The Export header "Export Time" will
   be of no use on the Collector side in this case as the flowStartNsec
   [IPFIX-INFO] and flowEndNsec [IPFIX-INFO] both have a nanosecond
   precision already.  Both flowStartNsec [IPFIX-INFO] and flowEndNsec
   [IPFIX-INFO] use the NTP time format which is represented as a 64-
   bit value which contains a 32-bit specification of seconds since
   1900 and a 32-bit "fraction" field.   Refer to the NTP
   specification, RFC1305, section 3.1 "Data Formats".

 8.4      Multiple Precisions

   When Flow Records requiring different precisions must be exported,
   the Exporting Process SHOULD split the Flow Records in different
   Data Set according to the precision: millisecond, microsecond or
   nanosecond.

 9.     Linkage with the Information Model

   The Information Elements [IPFIX-INFO] MUST be sent in canonical
   format in network byte order.

 9.1      Reduced Size Encoding of Integer Types

   Information Elements containing integer types in the information
   model MAY be encoded using fewer bytes than those implied by their
   type in the information model definition [IPFIX-INFO], based on the
   assumption that the smaller type is sufficient to carry any value
   the Exporter may need to deliver.  This reduces the network
   bandwidth requirement between the Exporter and the Collector.  Note
   that the Information Elements definition [IPFIX-INFO] will always
   define the maximum encoding size.

   For instance the information model [IPFIX-INFO] defines byteCount as
   an unsignedLong type, which would require 64-bits.  However if the
   Exporter will never locally encounter the need to send a value
   larger than 4294967295, it may chose to send the value instead as an
   unsignedInt.  For example, a core router would require an
   unsignedLong byteCount while an unsignedInt might be sufficient for
   an access router.



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   This behavior is indicated by the Exporter by specifying a type size
   smaller than that associated with the assigned type of the field.
   In the example above the Exporter would place a length of 4 versus 8
   in the template.

   If reduced sizing is used, it MUST be applied only to following
   integer types: unsignedLong, long, unsignedInt, int, unsignedShort,
   short.  In each case the downcasting MUST be to a smaller integer
   type.  The same signed versus unsigned properties MUST be preserved.
   Specifically unsignedLong may be downcast to unsignedInt,
   unsignedShort or unsignedByte.  A long may be downcast to an int, a
   short or a byte.  The other downcasts follow the same pattern.

 10.      Variable Length Information Element

   The IPFIX template mechanism is optimized for fixed length
   Information Elements [IPFIX-INFO].  Where an Information Element has
   a variable length the following mechanism MUST used to carry the
   length information, for both the IETF and proprietary Information
   Elements.

   In the Template Set the length is recorded as 65535.  This reserved
   length value notifies the Collecting Process that length of the
   Information Element will be carried in the Information Element
   content itself.

   In most cases the length of the Information Element will be less
   than 256 bytes.  The following length encoding mechanism optimizes
   the overhead of carrying the Information Element length in this
   majority case.

   If the length of the Information Element is less than 255 bytes, the
   length is carried in the first byte of the Information Element, as
   shown on Figure L.
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Length (< 255)|          Information element                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     Figure L: Variable Length Information Element (length < 255 bytes)


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   If the length of the Information Element is greater or equal than
   255 bytes, the first byte of the Information Element is 255, and the
   length is carried in the second and third bytes of the Information
   Element, as shown in Figure M.
       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |        Length (255 to 65535)       |   IE     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure M: Variable Length Information Element
               (length 255 to 65535) bytes

 11.      Template Management


   This section describes Template management when using SCTP and SCTP-
   PR as the transport protocol. Any necessary changes to Template
   management specifically related to TCP or UDP transport protocols
   are specified in section 13.

   The Exporting Process assigns and maintains the Template IDs for the
   ExporterÆs Observations Domains. A newly created Template Record is
   assigned an unused Template ID by the Exporting Process.

   Templates Sets and Option Template Sets MUST be only sent once on
   SCTP stream zero with full reliability.  As such, the Collecting
   Process MUST store the Template Record information for the duration
   of the association so that it can interpret the corresponding Flow
   Data Records that are received in subsequent Data Sets.

   New Template Records SHOULD be transmitted as soon as they are
   created. The Exporting Process MAY transmit the Template Set and
   Options Template in advance of any Data Sets that use that (Options)
   Template ID, to ensure that the Collector has the Template Record
   before receiving the first Flow or Options Data Record.  Flow and
   Options Data Records that correspond to a Template Record MAY appear
   in the same and/or subsequent IPFIX Message(s).





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   A Template ID MUST be unique per Observation Domain. Different
   Observation Domains from the same Exporter may use the same Template
   ID value to refer to different Templates.

   Disused Templates SHOULD be deleted. Prior to reuse a Template ID
   the disused Template MUST be deleted.  In order to delete an
   allocated Template, the Template is withdrawn through the use of a
   Template Withdraw Message.

   The Template Withdraw Message MUST not be sent until sufficient time
   has elapsed to allow the Collecting Process to receive and process
   the last data record using this Template information.

   The Template ID from a withdrawn Template MUST NOT be reused until
   sufficient time has elapsed to allow for the Collecting Process to
   receive and process the Template withdraw message.

   A Template Withdraw Message is Template Record for that Template ID
   with a Field Count of 0. The format of the Template Withdrawal
   Message is shown in figure O.

      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 or 3)       |          Length = 8           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Template ID          |        Field Count = 0        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure O: Template Withdrawal Message format

   The Set ID field MUST contain the value 2 for Template Set
   withdrawal, and the value 3 for Options Template Set.  Multiple
   Template ID MAY be withdrawn with a single Template Withdrawal
   Message: in that case, padding MAY be used.
   The Template Withdraw Message withdraws the Template ID for the
   Source ID specified in the IPFIX Message header.

   If the measurement parameters change, the Template MUST be withdrawn
   using a Template Withdraw Message or an unused Template ID MUST be
   used. Examples of the measurement changes are: a new sampling rate,
   a new flow expiration process, a new filtering definition, etc. If a



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   Template is changed, a Template Withdraw Message MUST be sent to
   delete the Template.

   If the Exporting Process restarts, the SCTP association MUST be
   shutdown and restarted. When the Exporting Process restarts, all
   Template assignments are lost and Template IDs MUST be re-assigned.
   If the Metering Process restarts, the Exporting Process MUST either
   reuse the previously assigned Template ID for each Template, or it
   MUST withdraw the previously issued Template IDs by sending Template
   Withdraw Message(s) before reusing them.  A Template Withdrawal
   Message to withdraw all Data Templates for the Source ID specified
   in the IPFIX message header MAY be used. Its format is shown in
   figure P. A Template Withdrawal Message to withdraw all Options
   Templates for the Source ID specified in the IPFIX message header
   MAY be used. Its format is shown in figure Q.

      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 = 8           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Template ID = 2       |        Field Count = 0        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure P: All Data Templates Withdrawal Message format

      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 = 3        |          Length = 8           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Template ID = 3       |        Field Count = 0        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure Q: All Options Templates Withdrawal Message format

   When the SCTP association restarts, the Exporting Process MUST
   resend all the Template Records.

   The Exporting Process MUST NOT transmit IPFIX Messages with more
   than one Source ID value inside any single stream.

   More that one (Option) Template Set MAY be sent in an IPFIX Message.


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 12.      The Collecting Process's Side

   This section describes the Collecting Process when using SCTP and
   SCTP-PR as the transport protocol. Any necessary changes to the
   Collecting Process specifically related to TCP or UDP transport
   protocols are specified in section 13.

   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.  A Collecting Process MUST
   support at least two inbound streams per association.  An Exporting
   Process MAY ask for and support more than two streams.

   The Collecting Process MUST verify that only one Source ID value is
   used inside each stream. If the Collecting Process detects that more
   than one Source ID has been received within a stream, it MUST
   discard the IPFIX Message, reset the SCTP association, and SHOULD
   log the error

   If the Collecting Process receives a malformed IPFIX Message, it
   MUST reset the SCTP association, discard the IPFIX Message, and
   SHOULD log the error.

   Templates Sets and Option Template Sets are only sent once.  The
   Collecting Process MUST store the Template Record information for
   the duration of the association so that it can interpret the
   corresponding Flow Data Records that are received in subsequent Data
   Sets.

   Template IDs are unique per Exporting Process and per Observation
   Domain.  If the Collecting Process receives a Template which has
   already been received but which has not previously been withdrawn
   (i.e. a Template Record from the same Exporter Observation Domain
   with the same Template ID), then the Collecting Process MUST
   shutdown the association.

   When an SCTP association is closed, the Collecting Process MUST
   discard all templates received over that association and stop
   decoding IPFIX Messages that use those templates.

   The Collecting Process normally receives Template Records from the
   Exporting Process, before receiving Flow or Options Data Records.


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   The Flow Data Records (or Options Data Records) are then decoded and
   stored by the Collector. If the Template Records have not been
   received at the time Flow Data Records (or Options Data Records) are
   received, the Collecting Process MAY store the Flow Data Records (or
   Options Data Records) for a short period of time and decode them
   after the Template Records are received.  A Collecting Process MUST
   NOT assume that the Data Set and the associated Template Set (or
   Options Template Set) are exported in the same IPFIX Message.

   The Collecting Process MUST note the Field ID of any Information
   Element that it does not understand and MAY discard that Information
   Element from the Flow Record.  The Collecting Process MUST note the
   size and position of any Vendor Specified Information Element that
   it does not understand and discard that Information Element from the
   Flow Record.

   More that one (Options) Template Set MAY be received in an IPFIX
   Message.

   The Collector MUST accept padding in Flow Data Records, Options Data
   Records and Template Records.

   The IPFIX protocol has a Sequence Number field in the Export header
   which increases with each IPFIX Message.  A Collector may detect out
   of sequence, dropped, or duplicate IPFIX Messages by tracking the
   Sequence Number.  EDITORÆS NOTE: THIS MIGHT CHANGE IF THE SEQUENCE
   NUMBER IS PER STREAM AND IF THIS IS THE NUMBER OF FLOW RECORDS. A
   collector SHOULD provide a logging mechanism for tracking out of
   sequence IPFIX Messages.  Such out of sequence IPFIX Messages may be
   due to Exporter resource exhaustion where it can not transmit
   messages at their creation rate, an Exporting Process reset,
   congestion on the network link between the Exporter and Collector,
   Collector resource exhaustion where it can not process the IPFIX
   Messages at their arrival rate, out of order packet reception,
   duplicate packet reception, or an attacker injecting false messages.

   If a Collecting Process receives a Template Withdraw Message, the
   Collecting Process MUST delete the corresponding Template Record
   associated with the specific Exporter and specific Observation
   Domain, and stop decoding IPFIX Messages that use those Templates.

   A Collecting Process that receives IPFIX Messages from several
   Observation Domains from the same Exporter MUST be aware that the


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   uniqueness of the Template ID is not guaranteed across Observation
   Domains.

   IPFIX Messages with a Source ID of zero MUST be discarded by the
   Collecting Process.

 13.      Transport Protocol

   The IPFIX Protocol Specification has been designed to be transport
   protocol independent.  Note that the Exporter can export to multiple
   Collecting Processes, using independent transport protocols.

   The IPFIX Message Header 16-bit LENGTH field limits the length of a
   IPFIX Message to 65536 octets including the header.  A Collecting
   Process MUST be able to handle IPFIX Message lengths of up to 65536
   octets.

 13.1       Transport Compliance and Transport Usage

   We need to differentiate between what must be implemented (so that
   operators can interoperably deploy compliant implementations from
   different vendors) and what should or could be used in various
   operational environments. We must also make sure that ALL
   implementations can operate in a congestion-aware and congestion
   avoiding mode.

   SCTP [RFC2960] and SCTP-PR [RFC3758] MUST be implemented by all
   compliant implementations.  UDP [UDP] MAY also be implemented by
   compliant implementations.  TCP [TCP] MAY also be implemented by
   compliant implementations.

   SCTP-PR SHOULD be used in deployments where Exporters and Collectors
   are communicating over links that are susceptible to congestion.
   SCTP-PR is capable of providing any required degree of reliability.

   TCP MAY be used in deployments where Exporters and Collectors
   communicate over links that are susceptible to congestion, but SCTP-
   PR is preferred, due to its ability to limit back pressure on
   Exporters and its message versus stream orientation.

   UDP MAY be used although it is not a congestion aware protocol.
   However, the IPFIX traffic between Exporter and Collector MUST
   remain wholly within the administrative domains of the operators.



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 13.2      TCP

   This section describes how IPFIX can be transported over TCP [TCP].

 13.2.1  Congestion Avoidance

   TCP will detect congestion in the end-to-end path between the IPFIX
   Exporting Process and the IPFIX Collecting Process, and limit the
   transfer rate accordingly.  When an IPFIX Exporting Process has
   records to export, but detects that transmission by TCP is
   temporarily impossible, it can either wait until sending is possible
   again, or it can decide to drop the record.  In the latter case, the
   dropped export data MUST be accounted for, so that the amount of
   dropped export data can be reported.

 13.2.2  Reliability

   TCP provides an intrinsically reliable delivery service from the
   IPFIX Exporting Process to the IPFIX Collecting Process.

 13.2.3  MTU

   TCP provides the required IPFIX Message fragmentation service based
   on path MTU discovery.

 13.2.4  Exporting Process

   The following sections describe how an IPFIX-over-TCP connection is
   created, how IPFIX data is transferred over it, and how a connection
   is to be terminated.

 13.2.4.1 Connection Establishment

   The IPFIX Exporting Process initiates a TCP connection to the IPFIX
   Collecting Process.  By default, the Collecting Process listens for
   connections on TCP port XXXX (to be assigned by IANA).  It MUST be
   possible to configure both the Exporting and Collecting Processes to
   use a different TCP port.

   An Exporting Process MAY support more than one active connection to
   different Collecting Processes (including the case of different
   Collecting Processes on the same host).



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 13.2.4.2 Connection Release

   When an Exporting Process has no more IPFIX Messages to send, it
   SHOULD close the TCP connection.

   When a Collecting Process no longer wants to receive IPFIX messages,
   it SHOULD close the TCP connection, but SHOULD continue to receive
   and process IPFIX messages until the Exporting Process has closed
   its end.

   When an Collecting Process detects that the TCP connection to the
   Exporting Process is abnormally terminated, it MUST continue to
   listen for a new connection.

   When an Exporting Process detects that the TCP connection is
   abnormally terminated, it SHOULD try to re-establish the connection.

   Connection timeouts SHOULD be configurable.

 13.2.4.3 IPFIX Message Encoding

   TCP provides message boundary marking marking mechanism. When IPFIX
   Message are sent over a TCP connection, the LENGTH field in the
   IPFIX Message header defines the end of each message and the start
   of the next message.

   If an Exporting Process exports data from multiple Observation
   Domains, it should be careful to choose the IPFIX Message lengths
   appropriately to avoid head-of-line blocking between different
   Observation Domains.

 13.2.5  Template Management

   New Template Records SHOULD be transmitted as soon as they are
   created on the Metering Process, and preferably before any
   associated Flow or  Options Data Record is transmitted.  The
   Collecting Process SHOULD accept Flow and Options Data Records
   without the associated Template Record.

   A Collecting Process MUST record all Template and Option Template
   Records for the duration of the connection, as an Exporting Process
   is not required to re-export Template Records.



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 13.2.6  Fail-over

   If the Collecting Process does not acknowledge the attempt by the
   Exporting Process to establish a connection, the Exporting Process
   should retry. The retry schedule SHOULD be configurable.  In the
   default configuration, an Exporting Process MUST NOT attempt to
   establish a connection more frequently than once per minute.

   The Exporter MAY log an alarm if the time to establish the
   association exceeds a specified threshold.

   If Collecting Process fail-over is supported by the Exporting
   Process a second TCP connection MAY be opened in advance.

 13.3       SCTP

   This section describes how IPFIX can be transported over SCTP
   [RFC2960] using the PR-SCTP [RFC3758] extension.

 13.3.1  Congestion Avoidance

   The SCTP transport protocol provides the required level of
   congestion avoidance by design.

   SCTP will detect congestion in the end-to-end path between
   the IPFIX Exporting Process and the IPFIX Collecting Process,
   and limit the transfer rate accordingly.  When an IPFIX
   Exporting Process has records to export, but detects that
   transmission by SCTP is temporarily impossible, it can either
   wait until sending is possible again, or it can decide to drop the
   record.  In the latter case, the dropped export data MUST
   be accounted for, so that the amount of dropped export data can be
   reported.

 13.3.2  Reliability

   The SCTP transport protocol is by default reliable, but has the
   capability to operate in unreliable and partially reliable modes
   [RFC3758].

   Using reliable SCTP streams (referred to hereafter as "streams") for
   the IPFIX export is not in itself a guarantee that all data records
   are delivered.  If there is congestion on the link from the


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   Exporting Process to the Collecting Process, or if a significant
   number of retransmissions are required, the send queues on the
   Exporting Process may fill up: the Exporting Process MAY either
   suspend export or discard IPFIX Messages.  If data records are
   discarded the sequence numbers used for export MUST reflect the loss
   of data.

 13.3.3  MTU

   SCTP provides the required IPFIX Message fragmentation service based
   on path MTU discovery.

 13.3.4  Exporting Process

 13.3.4.1 Association Establishment

   The IPFIX Exporting Process SHOULD initiate an SCTP association with
   the IPFIX Collecting Process.  By default, the Collecting Process
   listens for connections on SCTP port XXXX (to be assigned by
   IANA).  It MUST be possible to configure both the Exporting
   and Collecting Processes to use a different SCTP port.

   The Exporting Process MAY establish more than one associations
   (connection "bundle" in SCTP terminology) to the Collecting Process.

   An Exporting Process MAY support more than one active association
   to different Collecting Processes (including the case of different
   Collecting Processes on the same host).


 13.3.4.2 Association Shutdown

   When an Exporting Process has no more IPFIX Messages to send, it
   SHOULD shutdown the SCTP association.

   When a Collecting Process no longer wants to receive IPFIX
   Messages, it SHOULD shutdown its end of the association.  The
   Collecting Process SHOULD continue to receive and process
   IPFIX Messages until the Exporting Process has closed its end.

   When a Collecting Process detects that the SCTP association has been
   abnormally terminated, it MUST continue to listen for a new
   association establishment.


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   When an Exporting Process detects that the SCTP association to the
   Collecting Process is abnormally terminated, it SHOULD try to re-
   establish the association.

   Association timeouts SHOULD be configurable.


 13.3.4.3 Source ID

   The IPFIX Message MUST contain a Message Header, which includes a
   Source ID.  The Exporting Process uses the Source ID to uniquely
   identify to the Collecting Process the Observation Domain that
   metered the Flows.

 13.3.4.4 Stream

   An Exporting Process MUST request at least two outbound streams per
   association.  The first stream (referred to as stream zero in the
   rest of this document), is used to send the Template Set and the
   Options Template Set.  Stream zero MUST be fully reliable.  Data
   Sets MUST NOT be sent on stream zero.

   Depending on the application requirement, the Exporting Process
   selects the mode (unreliable, partially reliable, or fully reliable
   mode) of the stream, used to send the Data Sets.  Unreliable mode
   MAY be used where the application does not require reliable
   transmission and the use of a retransmission queue is impractical.

   An Exporter MAY use multiple streams to export Data Sets, in some
   cases different applications will have different requirements in
   terms of reliability.  In such a case, the Observation Domain MUST
   use the same Source ID value on all of the multiple streams it uses.
   Data Sets from multiple Observation Domains MUST NOT be transmitted
   over the same stream; the Collecting Process should however verify
   that the Source ID values are the expected values.

   When Data Sets are exported over a partially reliable stream, they
   SHOULD be marked for retransmission as long as there is room in the
   SCTP send queues.  However during times of congestion or other
   retransmission events, if the queue overflows, the oldest data
   record that has been transmitted and marked as partially reliable
   should be freed and marked to be skipped per the PR-SCTP [RFC3758]


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   specification.  The freed buffer space should then be re-used for
   the new Data Sets being exported.

 13.3.4.5 Template Management

   When the transport protocol is SCTP the default Template Management
   described in Section 12 is used.

 13.3.5  Collecting Process

   When the transport protocol is SCTP, the default Collector
   processing described in Section 13 is used.

 13.3.6  Failover

   If the Collecting Process does not acknowledge the attempt by the
   Exporting Process to establish an association it will retry using
   the SCTP exponential backoff feature.  The Exporter MAY log an alarm
   if the time to establish the association exceeds a specified
   threshold.

   If Collecting Process failover is supported by the Exporting Process
   a second SCTP association MAY be opened in advance.

 13.4       UDP

   This section describes how IPFIX can be transported over UDP
   [RFC768]

 13.4.1  Congestion Avoidance

   UDP has no integral congestion avoidance mechanism.  Its use
   over congestion sensitive network paths is therefore deprecated.
   UDP MAY be used in deployments where Exporters and Collectors
   always communicate over dedicated links that are not susceptible
   to congestion.

 13.4.2  Reliability

   UDP is not a reliable transport protocol, and cannot guarantee
   delivery of messages.  IPFIX Messages sent from the Exporting
   Process to the Collecting Process using UDP may therefore be lost.



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   UDP MUST NOT be used unless the application can tolerate some
   loss of Messages.

   The Collecting Process could deduce the loss and reordering of IPFIX
   Messages by looking at the discontinuities in the IPFIX Message
   sequence number.  These conditions SHOULD be logged.

   Templates sent from the Exporting Process to the Collecting
   Process using UDP as a transport MUST be resent at regular
   intervals in case previous copies were lost.  Implementations
   MAY send templates using a reliable transport protocol, and
   send IPFIX Flow and Option Data Records using UDP as the
   transport protocol.

 13.4.3  MTU

   The maximum size of exported messages MUST be configured such that
   the total packet size does not exceed the path MTU.

 13.4.4  Port Numbers

   By default, the Collecting Process listens on the UDP port XXXX (to
   be assigned by IANA).  It MUST be possible to configure both the
   Exporting and Collecting Processes to use a different UDP port.

 13.4.5  Exporting Process

   The Exporting Process MAY duplicate the IPFIX Message
   to the several Collecting Process.

 13.4.6  Template Management
   When IPFIX uses UDP as the transport protocol, Template Sets and
   Option Template Sets MUST be re-sent at regular intervals.  The
   frequency of (Options) Template transmission MUST be configurable.
   New Template Records SHOULD be transmitted as soon as they are
   created, and SHOULD be transmitted before any associated Data
   Record is transmitted.

   In the event of configuration changes, the Exporting Process SHOULD
   send the new template definitions at an accelerated rate.  In such a
   case, it MAY transmit the changed Template Record(s) and Options
   Template Record(s), without any data, in advance to help ensure that



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   the Collector will have the correct template information before
   receiving the first data.

   If the Option Template scope is defined in another Template, then
   both Templates SHOULD be sent in the same IPFIX Message. For
   example: if a Flow Key Option Template (see section 8.3) is sent in
   an Option Template, then the associated Template SHOULD be sent in
   the same IPFIX Message.

   Note that following a configuration change a new Template ID should
   be used and the old Template ID SHOULD NOT be reused until its
   lifetime has expired.

   Template Withdraw Messages SHOULD NOT be sent over UDP.

 13.4.7   Collecting Process

   The Collecting Process SHOULD accept Flow and Options Data Records
   without the associated Template Record. If the Template Records have
   not been received at the time Flow Data Records (or Options Data
   Records) are received, the Collecting Process SHOULD store the Flow
   Data Records (or Options Data Records) for a short period of time
   and decode them after the (Options) Template Records are received.
   The short period of time MUST be lower than the Template lifetime.

   The lifetime of a template at the Collecting Process is limited to a
   fixed refresh timeout.  The Collecting Process MUST associate a
   lifetime with each Template received via UDP.  Templates not
   refreshed by the Exporting Process within the timeout are expired at
   the Collecting Process.  If the template is not refreshed by the
   Exporting Process before that lifetime has expired, the Collecting
   Process MUST discard the Template, and any current and future
   associated Flow or Option Data Records.  The Collecting Process MUST
   NOT decode any further Flow or Option Data Records which are
   associated with that expired Template.

   At any given time the Collecting Process SHOULD maintain the
   following for all the current Template Records and Options Template
   Records: <Exporting Process, Observation Domain, Template ID,
   Template Definition, Last Received>.





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 13.4.8  Failover

   Because UDP is not a connection oriented protocol, the Exporting
   Process is unable to determine from the transport protocol that the
   Collecting Process is no longer able to receive the IFPIX Messages.
   Therefore, it can not invoke a failover mechanism.  However, the
   Exporting Process MAY duplicate the IPFIX Message to several
   Collecting Processes.

 14.      Security Considerations

   Because IPFIX can be used to collect billing information and network
   forensics, confusing or blinding IPFIX must be seen as a prime
   objective during a sophisticated network attack.

   If an attacker is in a position to inject false messages into an
   IPFIX Message stream this will allow them to send forged Flow Data
   Records, Options Data Records, or Templates.  Forged Templates may
   impair the Collectors ability to process any further Flow Records.
   Forged Flow Records would have a direct effect on the application
   using the Flows, for example a billing system may generate incorrect
   billing information.  Forged options may be able to alter the
   meaning of Flow Records, for example if the sample rate is changed.

   The IPFIX Messages themselves may contain information of value to an
   attacker, and thus care must be taken to confine their visibility to
   authorized users.

   IPFIX Messages can be secured using IPsec.  Alternatively if IPFIX
   runs on top of SCTP or TCP, TLS [TLS] can be used.

   When an Information Element containing end-user payload information
   is exported, it SHOULD be transmitted to the Collecting Process
   using a means that secures its contents against eavesdropping.
   Suitable mechanisms include the use of either a direct point-to-
   point connection or the use of an encryption mechanism. It is the
   responsibility of the Collecting Process to provide a satisfactory
   degree of security for this collected data, including, if necessary,
   anonymization of any reported data.

 14.1       IPsec Usage

   To secure messages between the Exporter and the Collector an IPFIX


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   implementation MAY use IPsec.  To ensure interworking between
   Exporters and Collectors from different vendors, the following IPsec
   profile MUST be supported.  This profile is derived from [USEIPSEC].

 14.1.1  Selectors

   IPFIX runs between manually configured pairs of hosts on the
   following transport ports (TBD).  The appropriate selector would be
   Exporter-Collector pairs and port number.

   Note that, if the Exporter is a router, a non-interface ("loopback")
   address should be used.

 14.1.2  Mode

   IPsec MUST be run in transport mode.  The AH and ESP MUST be
   supported by an IPFIX implementation of IPsec.

   The Authentication Header (AH) [RFC2402] MUST be used if
   authentication is required.  The Security Protocol (ESP) [RFC2406]
   must be used if there is a threat to the IPFIX Message content, or
   if that content is confidential.

   Normally in situations where the ESP was required the AH would also
   be required.  If ESP only is used, the sender's IP address MUST be
   checked against the IP address asserted in the key management
   exchange.

 14.1.3  Key Management

   In many networks, manual key management will be sufficient, and this
   reduces the complexity of the Exporter, albeit at a cost of greater
   configuration complexity.  Manual key management MUST be supported.
   If a replay attack is considered likely, an automated key management
   such as IKE [IKE] key management system SHOULD be used.

 14.1.4  Security Policy

   Connections should be accepted only from the designated peer.

 14.1.5  Authentication




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   Given the number of IPFIX capable Exporters that are likely to be
   deployed by large ISPs, there will be circumstances where shared key
   mechanisms are not adequate.  Where an automated key management
   system is used, certificate-based IKE SHOULD be supported.

 14.1.6  Availability

   It is accepted that IPsec will not be universally available in IPFIX
   Exporters, and that where it is available, there may be issues of
   throughput, which may itself raise security issues.  In such
   circumstances the other security measures described in this document
   provide some threat mitigation.

 14.2       TLS Usage

   The IPFIX Exporter initiating a connection acts as a TLS client
   according to [TLS], and an IPFIX Collector that accepts a connection
   acts as a TLS server.  If mutual authentication is required the
   IPFIX Device acting as TLS server MUST request a certificate from
   the IPFIX Device acting as TLS client, and the IPFIX Device acting
   as TLS client MUST be prepared to supply a certificate on request.

 14.3       Protection against DoS attacks

   An attacker may directly mount a DoS attack by generating large
   amounts of traffic.   If TCP is used for transport, then the Flow to
   the Collector would back off due to congestion and eventually stall,
   blinding the IPFIX system.  An attack could then proceed without
   further observation.  SCTP-PR will have a different pathology under
   such an attack.  Stale data at the head of the queue will get
   flushed giving some visibility of the attack.  In case of UDP, IPFIX
   would reduce to some sort of sampling, meaning that some forensics
   may be left.

   To avoid blinding of the IPFIX system some mechanism for service
   differentiation can be used to prioritize IPFIX traffic over user
   traffic.  An alternative is to use a dedicated network for the
   transport of IPFIX Messages.  By sending the IPFIX Messages over a
   dedicated network, IPFIX Message loss induced by user traffic
   congestion is minimized.  However an attacker may trigger the
   generation of excessive IPFIX Messages, and to avoid information
   loss during such an attack the IPFIX network must be adequately
   sized.


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 14.4       When IPsec or TLS is not an option

   The use of IPsec or TLS might not be an option because of
   performance issues.

   Without IPsec or TLS an IPFIX entity has no means to authenticate an
   IPFIX entity other than the Source IP address.  Useful protection is
   gained by allocating Exporter and Collector IP addresses from ranges
   that are excluded from use by user traffic and preventing spoofing
   attacks by proper ingress filtering.  Where large numbers of
   Exporters, proxies and Collectors are used in a network, it may be
   tempting for the administrator to not impose source IP address
   restrictions but this leaves a proxy or Collector open to the
   reception of invalid information.  Using an open proxy or Collector
   is therefore discouraged.

   If IP address spoofing can not be prevented some level of protection
   against an insertion attack is required.  With a modern
   implementation of TCP with good ISN randomization [XXX-REFERENCE] or
   SCTP insertion such attacks are difficult without the ability to
   snoop the packet Flow [XXX-SCTP-BLIND-SPOOFING-REFERENCE].  UDP is
   vulnerable to insertion attacks, however, randomization of the IPFIX
   Sequence Number might mitigate this problem.  In all these cases,
   the Sequence Number space is relatively small giving only limited
   protection.  Therefore a 64 bit cookie [L2TPv3] SHOULD be included
   as an element within all messages.

   The use of a dedicated network prevents IPFIX Messages from being
   inspected by an attacker.

 14.5       Logging an IPFIX Attack

   A Collector may detect problems by tracking the IPFIX Sequence
   Number and therefore SHOULD provide a logging mechanism for tracking
   out of sequence messages.  Such out of sequence messages may not
   only be caused by network congestion or Exporter/Collector resource
   exhaustion but also by an attacker injecting false messages.

   Note that an attacker may be able to exploit the behavior of the
   Collector when it receives an out of sequence message.  For example
   a Collector that simply reset the expected Sequence Number upon
   receipt of a later message would easily be temporarily blinded by



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   deliberately injecting messages with a much larger Sequence Number.

   [EDITOR NOTE: the security section may need be adapted to the
   revised transport section]

 15.      IANA Considerations

   The IPFIX Protocol, as set out in this document, has two sets of
   assigned numbers.  Considerations for assigning them are discussed
   in this section, using the example policies as set out in the
   "Guidelines for IANA Considerations" document IANA-RFC [RFC2434].

 15.1       Numbers used in the Protocol

   IPFIX Messages use two fields with assigned values.  These are the
   IPFIX Version Number, indicating which version of the IPFIX Protocol
   was used to export an IPFIX Message, and the IPFIX Set ID,
   indicating the type for each set of information within an IPFIX
   Message.

   Changes in either IPFIX Version Number or IPFIX Set ID assignments
   require an IETF Consensus, i.e. they are to be made via RFCs
   approved by the IESG.

 15.2       Numbers used in the Information Model

   Fields of the IPFIX protocol carry information about traffic
   measurement. They are modeled as elements of the IPFIX information
   model [IPFIX-INFO]. Each Information Element describes a field which
   may appear in an IPFIX Message. Within an IPFIX Message the field
   type is indicated by its Field Type.

   New assignments for IPFIX Field Types will be administered by IANA,
   on First Come First Serve basis [RFC 2434] , subject to Expert
   Review [RFC 2434], i.e. review by one of a group of experts
   designated by an IETF Operations and Management Area Director. The
   group of experts must double check the Information Elements
   definitions for completeness, accuracy and redundancy with already
   defined Information Elements. Those experts will initially be drawn
   from the Working Group Chairs and document editors of the IPFIX and
   PSAMP Working Groups. The IANA assignments for IPFIX Field Types
   will range from 128 to 32767; the values below 128 are reserved or




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   assigned already; the values ranging from 32768 to 65535 are
   allocated for private use by vendors.

 16.      Examples

   Let's consider the example of an IPFIX Message composed of a
   Template Set, a Data Set (which contains three Flow Data Records),
   an Options Template Set and a Data Set (which contains 2 Options
   Data Records).

   IPFIX Message:

   +--------+---------------------------------------------. . .
   |        | +--------------+ +-----------------------+
   |Message | | Template     | | Data                  |
   | Header | | Set          | | Set                   |   . . .
   |        | | (1 Template) | | (3 Flow Data Records) |
   |        | +--------------+ +-----------------------+
   +--------+---------------------------------------------. . .

        . . .+-------------------------------------------------+
             +------------------+ +--------------------------+ |
             | Options          | | Data                     | |
        . . .| Template Set     | | Set                      | |
             | (1 Template)     | | (2 Options Data Records) | |
             +------------------+ +--------------------------+ |
        . . .--------------------------------------------------+

 16.1       Message Header Example

   The Message Header is composed of:
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Version = 0x000a          |         Length = 152          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Export Time                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Sequence Number                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Source ID                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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 16.2       Template Set Examples

 16.2.1  Template Set using IETF specified Information Elements

   We want to report the following Field Types:
   - The source IP address (IPv4), so the length is 4
   - The destination IP address (IPv4), so the length is 4
   - The next-hop IP address (IPv4), so the length is 4
   - The number of bytes of the Flow
   - The number of packets of the Flow

   Therefore, the Template Set will be composed of the following:

    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 = 28 bytes        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Template ID 256         |       Field Count = 5         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     IP_SRC_ADDR = 0x0008      |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     IP_DST_ADDR = 0x000C      |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     IP_NEXT_HOP = 0x000F      |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       IN_PKTS = 0x0002        |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       IN_BYTES = 0x0001       |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 16.2.2  Template Set using Enterprise Specific Information Elements

      We want to report the following Field Types:
      - The source IP address (IPv4), so the length is 4
      - The destination IP address (IPv4), so the length is 4
      - An Enterprise Specific Field representing proprietary
        information, with a type of 0x000F and a length of 4
      - The number of bytes of the Flow
      - The number of packets of the Flow

      Therefore, the Template Set will be composed of the following:


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       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 = 28 bytes        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID 256         |       Field Count = 5         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     IP_SRC_ADDR = 0x0008      |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     IP_DST_ADDR = 0x000C      |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1| Enterprise Field Type=0x000F|       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Enterprise number                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       IN_PKTS = 0x0002        |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       IN_BYTES = 0x0001       |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 16.3       Data Set Example

   In this example, we report the following three Flow Records:
   Src IP addr. | Dst IP addr.  | Next Hop addr. | Packet | Bytes
                |               |                | Number | Number
   ------------------------------------------------------------------
   192.168.1.12 | 192.168.2.254 | 192.168.1.1    | 5009   | 5344385
   192.168.1.27 | 192.168.2.23  | 192.168.1.2    | 748    | 388934
   192.168.1.56 | 192.168.2.65  | 192.168.1.3    | 5      | 6534

    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 = 256         |          Length = 64          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.12                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.2.254                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.1                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             5009                              |


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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            5344385                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.27                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.2.23                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.2                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              748                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             388934                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.56                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.2.65                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.3                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               5                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              6534                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Note that padding is not necessary in this example.

 16.4       Options Template Set Examples

 16.4.1  Options Template Set using IETF specified Information Elements

   Per line card (the router being composed of two line cards), we want
   to report the following Field Types:
      - Total number of IPFIX Messages
      - Total number of exported Flows

   Each line card is characterized by an unique Observation Domain,
   represented by the unique Source ID Information Elements [IPFIX-
   INFO]. As a consequence, the Scope Field is the Source ID
   Information Element.

   Therefore, the Options Template Set will be:

    0                   1                   2                   3


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    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 = 3            |          Length = 24          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Template ID 257         |        Field Count = 3        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Scope Field Count = 1     | Scope 1 Field Type = 141      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Scope 1 Field Length = 4    |    TOTAL_EXP_PKTS_SENT = 41   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |     TOTAL_FLOWS_EXP = 42      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 16.4.2  Options Template Set using Enterprise Specific Information
     Elements
   Per line card (the router being composed of two line cards), we want
   to report the following Field Types:
      - Total number of IPFIX Messages
      - An Enterprise Specific number of exported Flows,
        with a type of 42 and a length of 4

   Each line card is characterized by an unique Observation Domain,
   represented by the unique Source ID Information Elements [IPFIX-
   INFO]. As a consequence, the Scope Field is the Source ID
   Information Element.

   The format of the Options Template Set is as follows:

    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 = 3            |          Length = 24          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Template ID 257         |        Field Count = 3        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Scope Field Count = 1     |   Scope 1 Field Type = 141    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Scope 1 Field Length = 4    |    TOTAL_EXP_PKTS_SENT = 41   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |1| Enterprise Field Type = 42  |


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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |       Enterprise number      ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ...      Enterprise number       |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 16.4.3  Options Template Set using an Enterprise Specific scope
   In this example, we want to export the same information as in the
  example in section 16.4.2:
      - Total number of IPFIX Messages
      - Total number of exported Flows

   But this time, the information pertains to a proprietary scope,
   identified by Enterprise Specific Information Element number 123.

   The format of the Options Template Set is now as follows:

    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 = 3            |          Length = 28          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Template ID 257         |        Field Count = 3        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Scope Field Count = 1     |1|  Scope 1 Field Type = 123   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Enterprise Number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Scope 1 Field Length = 4    |    TOTAL_EXP_PKTS_SENT = 41   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |     TOTAL_FLOWS_EXP = 42      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 16.5       Data Set with Options Data Records Example

   In this example, we report the following two Options Data Records:
   Line Card ID             | IPFIX Message   | Exported Flow Records
   ------------------------------------------------------------------
   Line Card 1 (SourceID=1) | 345             | 10201
   Line Card 2 (SourceID=2) | 690             | 20402


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   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 = 257             |         Length = 20           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                               1                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |             345               |            10201              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                               2                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |             690               |            20402              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 17.     References

 17.1       Normative References

   [IPFIX-ARCH] Sadasivan, G, Brownlee, N. "Architecture Model for IP
   Flow Information Export" draft-ietf-ipfix-arch-02.txt", October 2003

   [IPFIX-INFO] Calato, P, Meyer, J, Quittek, J, "Information Model for
   IP Flow Information Export" draft-ietf-ipfix-info-02, November 2003

   [UDP]  Postel, J., "User Datagram Protocol" RFC 768, August 1980

   [TCP]  "TRANSMISSION CONTROL PROTOCOL DARPA INTERNET PROGRAM
   PROTOCOL SPECIFICATION" RFC 793, September 1981

   [RFC1889] Schulzrinne, H., Casner, S., Frederick, R., Jacobson, V.,
   "RTP: A Transport Protocol for Real-Time Applications ", RFC 1889,
   January 1996

   [RFC2434] Alvestrand, H. and T. Narten, "Guidelines for Writing an
   IANA Considerations Section in RFCs", RFC 2434, October 1998.

   [RFC2402] Kent, S., Atkinson, R., "IP Authentication Header ", RFC
   2402, November 1998

   [RFC2406] Kent, S., Atkinson, R., "IP Encapsulating Security Payload
   (ESP)", RFC 2406, November 1998



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   [RFC2960] Stewart, R. (ed.) "Stream Control Transmission Protocol",
   RFC 2960, October 2000

   [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., Conrad, P.
   "Stream Control Transmission Protocol (SCTP) Partial Reliability
   Extension", RFC 3758, May 2004

 17.2       Informative References

   [IPFIX-REQ] Quittek, J, Zseby, T, Claise, B, Zander, S,
   "Requirements for IP Flow Information Export" draft-ietf-ipfix-reqs-
   15.txt, June 2003

   [IPFIX-AS] Zseby, T, Penno, R, Brownlee, N, Claise, B, "IPFIX
   Applicability", draft-ietf-ipfix-as-01.txt, October 2003

   [IPFIX-EVAL] Leinen, S, "Evaluation of Candidate Protocols for IP
   Flow Information Export (IPFIX)", draft-leinen-ipfix-eval-contrib-
   02.txt, January 2003

   [NETFLOW9] Claise, B, et al "Cisco Systems NetFlow Services Export
   Version 9", draft-claise-netflow-9-07.txt, December 2003

   [PEN] IANA Private Enterprise Numbers registry
         http://www.iana.org/assignments/enterprise-numbers

   [USEIPSEC] S. Bellovin, Guidelines for Mandating the Use of IPsec,
              draft-bellovin-useipsec-02.txt, October 2003, work
              in progress.

   [IKE]      Harkins, D. and D. Carrel, "The Internet Key Exchange
              (IKE)", RFC 2409, November 1998.

   [TLS]      Dierks, T. and C. Allen, "The TLS Protocol Version
              1.0", RFC 2246, January 1999.

   [L2TPv3]   J. Lau et al. Layer Two Tunneling Protocol (Version 3)
              draft-ietf-l2tpext-l2tp-base-11.txt, October 2003, work
              in progress.

   [XXX-REFERENCE]

   [XXX-SCTP-BLIND-SPOOFING-REFERENCE]


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 18.      Acknowledgments

   We would like to thank the following persons: Juergen Quittek for
   the coordination job; Nevil Brownlee and Dave Plonka for the
   thorough reviews; Randall Stewart and Peter Lei for their SCTP
   expertise;  Martin Djernaes for the first essay on the SCTP section;
   Simon Leinen for the first essay on the TCP section Sebastian
   Zander, Jeff Meyer, Maurizio Molina, Carter Bullard, Tal Givoly, and
   many more, for the technical feedback.

 Authors Addresses

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

   Stewart Bryant
   Cisco Systems, Inc.
   250, Longwater,
   Green Park,
   Reading, RG2 6GB,
   United Kingdom
   Phone: +44 (0)20 8824-8828
   Email: stbryant@cisco.com

   Ganesh Sadasivan
   Cisco Systems, Inc.
   170 W. Tasman Dr.
   San Jose, CA 95134
   USA
   Phone: +1 (408) 527-0251
   Email: gsadasiv@cisco.com

   Mark Fullmer
   OARnet
   2455 North Star Rd.
   Columbus, Ohio 43221
   Phone: +1 (614) 728-8100



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   Email: maf@eng.oar.net

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Copyright Statement


  Claise, et. al            Standard Track                   [Page 61]

                   IPFIX Protocol Specification          December 2004



Copyright (C) The Internet Society (2004).  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.














































  Claise, et. al            Standard Track                   [Page 62]


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