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   IPFIX working group
   Internet Draft                               EDITOR:      B. Claise
   draft-ietf-ipfix-protocol-15.txt                       Cisco Systems
   Expires: November 30, 2005                                  May 2005





                       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 BCP 79.

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   This Internet-Draft will expire on November 30, 2005.

 Copyright Notice

   Copyright (C) The Internet Society (2005).

 Abstract

   This document specifies the IPFIX protocol that serves for
   transmitting IP traffic flow information over the network.  In order
   to transmit IP traffic flow information from an exporting process to
   an information collecting process, a common representation of flow


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   data and a standard means of communicating them is required. This
   document describes how the IPFIX data and templates records 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. Introduction...................................................4
      1.1 IPFIX Documents Overview.....................................4
     2. Terminology....................................................5
      2.1 Terminology Summary Table....................................9
     3. IPFIX Message Format..........................................10
      3.1 Message Header Format.......................................12
      3.2 Field Specifier Format......................................13
      3.3 Set and Set Header Format...................................15
     3.3.1   Set Format...............................................15
     3.3.2   Set Header Format........................................16
      3.4 Record Format...............................................16
     3.4.1   Template Record Format...................................16
     3.4.2   Options Template Record Format...........................19
     3.4.2.1  Scope...................................................19
     3.4.2.2  Options Template Record Format..........................20
     3.4.3   Data Record Format.......................................22
     4. Specific Reporting Requirements...............................23
      4.1 The Metering Process Statistics Option Template.............24
      4.2 The Metering Process Reliability Statistics Option Template.25
      4.3 The Exporting Process Reliability Statistics Option Template26
      4.4 The Flow Keys Option Template...............................27
     5. IPFIX Message Header "Export Time" and Flow Record Time.......28
     6. Linkage with the Information Model............................28
      6.1 Encoding of IPFIX Data Types................................28
     6.1.1   Integral Data Types......................................29
     6.1.2   Address Types............................................29
     6.1.3   float32..................................................29
     6.1.4   boolean..................................................29
     6.1.5   string and octetarray....................................29
     6.1.6   dateTimeSeconds..........................................29
     6.1.7   dateTimeMilliSeconds.....................................30
     6.1.8   dateTimeNanoSeconds......................................30
     6.1.9   dateTimeMicroSeconds.....................................30
      6.2 Reduced Size Encoding of Integer Types......................30
     7. Variable Length Information Element...........................31


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     8. Template Management...........................................32
     9. The Collecting Process's Side.................................35
     10. Transport Protocol...........................................37
      10.1 Transport Compliance and Transport Usage...................37
      10.2 SCTP.......................................................38
     10.2.1  Congestion Avoidance.....................................38
     10.2.2  Reliability..............................................38
     10.2.3  MTU......................................................38
     10.2.4  Exporting Process........................................39
     10.2.4.1 Association Establishment...............................39
     10.2.4.2 Association Shutdown....................................39
     10.2.4.3 Stream..................................................39
     10.2.4.4 Template Management.....................................40
     10.2.5  Collecting Process.......................................40
     10.2.6  Failover.................................................40
      10.3 UDP........................................................41
     10.3.1  Congestion Avoidance.....................................41
     10.3.2  Reliability..............................................41
     10.3.3  MTU......................................................42
     10.3.4  Port Numbers.............................................42
     10.3.5  Exporting Process........................................42
     10.3.6  Template Management......................................42
     10.3.7  Collecting Process.......................................43
     10.3.8  Failover.................................................43
      10.4 TCP........................................................44
     10.4.1  Connection Management....................................44
     10.4.1.1 Connection Establishment................................44
     10.4.1.2 Graceful Connection Release.............................44
     10.4.1.3 Restarting Interrupted Connections......................44
     10.4.1.4 Failover................................................45
     10.4.2  Data Transmission........................................45
     10.4.2.1 IPFIX Message Encoding..................................45
     10.4.2.2 Templates...............................................45
     10.4.2.3 Congestion Handling and Reliability.....................46
     11. Security Considerations......................................47
      11.1 IPsec Usage................................................47
     11.1.1  Selectors................................................47
     11.1.2  Mode.....................................................48
     11.1.3  Key Management...........................................48
     11.1.4  Security Policy..........................................48
     11.1.5  Authentication...........................................48
     11.1.6  Availability.............................................48
      11.2 TLS Usage..................................................49
      11.3 Protection against DoS attacks.............................49
      11.4 When IPsec or TLS is not an option.........................49
      11.5 Logging an IPFIX Attack....................................50
     12. IANA Considerations..........................................50
      12.1 Numbers used in the Protocol...............................51
      12.2 Numbers used in the Information Model......................51


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     13. Examples.....................................................51
      13.1 Message Header Example.....................................52
      13.2 Template Set Examples......................................52
     13.2.1  Template Set using IETF specified Information Elements...52
     13.2.2  Template Set using Enterprise Specific Information
     Elements.........................................................53
      13.3 Data Set Example...........................................54
      13.4 Options Template Set Examples..............................55
     13.4.1  Options Template Set using IETF specified Information
     Elements.........................................................55
     13.4.2  Options Template Set using enterprise-specific
     Information Elements.............................................56
     13.4.3  Options Template Set using an enterprise-specific scope..57
     13.4.4  Data Set using an enterprise-specific scope..............58
     14. References...................................................58
      14.1 Normative References.......................................58
      14.2 Informative References.....................................59
     15. Acknowledgments..............................................60


 1.     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.

 1.1      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
   [RFC3917].  This document specifies how IPFIX data record and
   templates are carried via a congestion-aware transport protocol from
   IPFIX exporting processes to IPFIX collecting process.  IPFIX has a


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   formal description of IPFIX information elements, 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.

 2.    Terminology

   The definitions of the basic terms like IP Traffic Flow, Exporting
   Process, Collecting Process, Observation Points, etc. are
   semantically identical with those found in the IPFIX requirements
   document [RFC3917].  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.

   The terminology summary table in Section 2.1 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
   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




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   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.

 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)



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   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 for all the
   Flow's packets) and usually characteristic properties of the Flow
   (e.g. source IP address).

 Metering Process

   The Metering Process generates Flow Records.  Inputs to the process
   are packet headers and characteristics 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.

 Exporter

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

 IPFIX Device

   An IPFIX Device hosts at least one Observation Point, a Metering
   Process and an Exporting Process.

 Collecting Process


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   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 <type, length> pairs, used to
   completely specify the structure and semantics of a particular set
   of information that needs to be communicated from an IPFIX Device to
   a 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 a Collecting Process.  An IPFIX Message is
   encapsulated within a transport layer.

 Message Header

   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 Data Record.

 Data Record

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

 Options Template Record


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

   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 Data Records, of the same type, that are
   grouped together in an IPFIX Message.  Each Data Record is
   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 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 determines the valid encoding mechanisms for use in IPFIX.

 2.1      Terminology Summary Table



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    +------------------+---------------------------------------------+
    |                  |                 Contents                    |
    |                  +--------------------+------------------------+
    |       Set        |      Template      |         Record         |
    +------------------+--------------------+------------------------+
    |   Data Set       |          /         |     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 Data Record(s).  No Template Record is
   included.  A Template Record or an Options Template Record defines
   the Data Record.

   A Template Set contains only Template Record(s).

   An Options Template Set contains only Options Template Record(s).

 3.     IPFIX 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: Data
   Set, Template Set or Options Template Set.

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

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



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         Figure B: IPFIX Message format

   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
   Template Sets are interleaved with this information, subject to
   availability of space.

   +--------+--------------------------------------------------------+
   |        | +----------+ +---------+     +-----------+ +---------+ |
   |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, Template
   Sets and Option Template Sets MUST be sent periodically to ensure




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   that the Collecting Process has the Template Records and Options
   Template Records when the corresponding Data Records are received.

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

      Figure E: IPFIX Message example 3

 3.1      Message 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




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           Time in seconds since 0000 UTC Jan 1st 1970, at which the
           IPFIX Message Header leaves the Exporter.

   Sequence Number
           Incremental sequence counter modulo 2^32 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
           A 32-bit identifier of the Observation Domain that is
           locally unique to the Exporting Process.  The Exporting
           Process uses the Source ID to uniquely identify to the
           Collecting Process the Observation Domain that metered the
           Flows.  Collecting Processes SHOULD use the combination the
           combination of the Exporter (exporterIPv4Address,
           exporterIPv6Address, or exportingProcessId) and the Source
           ID field to separate different export streams originating
           from the same Exporting Process.  The Source ID SHOULD be 0
           when no specific Source ID is relevant for the entire IPFIX
           Message.  For example, when exporting the Exporting Process
           Statistics, or in case of hierarchy of Collector when
           aggregated data records are exported.  The Source ID MUST be
           zero when the IPFIX Message contains data records with
           different Source ID values defined as scopes.

 3.2      Field Specifier Format

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

   The Information Elements are identified by the Information Element
   identifier. When the Enterprise bit is set to 0, the corresponding
   Information Element identifier will report an IETF specified
   Information Element, and the Enterprise Number MUST NOT be present.
   When the Enterprise bit is set to 1, the corresponding Information
   Element identifier will report an enterprise-specific Information



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   Element and the Enterprise Number MUST be present.  An example of
   this is shown in section 13.4.2

   The Field Specifier 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|  Information Element ident. |        Field Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Enterprise Number                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Figure G: Field Specifier format

        Where:

       E
          Enterprise bit.  This is the first bit of the Field
          Specifier. If this bit is zero, the Information Element
          Identifier identifies an IETF specified Information Element,
          and the four octet Enterprise Number field MUST NOT be
          present.  If this bit is one, the Information Element
          identifier identifies an enterprise-specific Information
          Element, and the Enterprise Number filed MUST be present.

       Information Element identifier
           A numeric value that represents the type of the Information
           Element.  Refer to [IPFIX-INFO].

       Field Length
           The length of the corresponding encoded Information Element,
           in octets.  Refer to [IPFIX-INFO].  The field length may be
           smaller than the definition in [IPFIX-INFO] if reduced size
           encoding is used (see section 6.2).  The value 65535 is
           reserved for variable length Information Element (see
           section 7). The Field Length MAY NOT 0.

      Enterprise Number
         IANA enterprise number [PEN] of the authority defining the
         Information Element identifier in this Template Record.




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 3.3      Set and Set Header Format

   A Set is a generic term for a collection of records that have a
   similar structure.  There are three different types of Sets:
   Template Sets, Options Template Sets, and Data Sets. Each of these
   Sets consists of a Set Header and one or more Records. The Set
   Format and the Set Header Format are defined in the following
   sections.

 3.3.1   Set Format

   A Set has the format shown in figure H. The records types can be
   either Template Records, Option Template Records or Data Records.
   The record types MUST NOT be mixed within a Set.

         +--------------------------------------------------+
         | Set Header                                       |
         +--------------------------------------------------+
         | record                                           |
         +--------------------------------------------------+
         | record                                           |
         +--------------------------------------------------+
          ...
         +--------------------------------------------------+
         | record                                           |
         +--------------------------------------------------+
         | Padding (opt.)                                   |
         +--------------------------------------------------+

              Figure H: Set Format

      The Set Field Definitions are as follows:

      Set Header
          The Set Header Format is defined in section 3.3.2.

      Record
         One of the Record Formats: Template Record or Option
         Template Record or Data Record Format.

      Padding
         The Exporting Process MAY insert some padding octets, so that
         the subsequent Set starts at an aligned boundary.  Padding


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         MUST be composed of zero (0) octets.  The padding length MUST
         be shorter than any allowable record in this Set.  Because
         Template Sets are always 4-octet aligned by definition
         padding is only needed in case of other alignments e.g. on 8-
         octet boundaries.

 3.3.2   Set Header Format

   Every Set contains a common header. This header is defined 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Set ID               |          Length               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure I: Set Header Format

   The Set Header Field Definitions are as follows:

      Set ID
         Set ID value identifies the Set. A value of 2 is reserved for
         the Template Set.  A value of 3 is reserved for the Option
         Template Set.  All other values from 4 to 255 are reserved
         for future use.  Values above 255 are used for Data Sets. The
         Set ID values of 0 and 1 are not used for historical reasons
         [RFC3954].

      Length
          Total length of the Set in octets including the Set Header,
          all records and the optional padding.  Because an individual
          Set MAY contain multiple records, the Length value MUST be
          used to determine the position of the next Set.

 3.4      Record Format

   IPFIX defines three record formats, defined in the next sections:
   the Template Record Format, the Option Template Record Format and
   the Data Record Format.

 3.4.1   Template Record Format



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   One of the essential elements in the IPFIX record format is the
   Template Record.  Templates greatly enhance the flexibility of the
   record format because they allow the Collecting Process to process
   IPFIX Messages without necessarily knowing the interpretation of all
   Data Records. A Template Record contains any combination of IANA-
   assigned and/or enterprise-specific Information Elements
   identifiers.

   The format of the Template Record is shown in Figure J.  It consists
   of a Template Record Header and one or more Field Specifiers.  The
   definition of the Field Specifiers is given in figure G above.

         +--------------------------------------------------+
         | Template Record Header                           |
         +--------------------------------------------------+
         | Field Specifier                                  |
         +--------------------------------------------------+
         | Field Specifier                                  |
         +--------------------------------------------------+
          ...
         +--------------------------------------------------+
         | Field Specifier                                  |
         +--------------------------------------------------+

               Figure J: Template Record Format

   The format of the Template Record Header 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID (> 255)      |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure K: Template Record Header Format

   The Template Record Header Field Definitions are as follows:

      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.  Template IDs 0-255 are
         reserved for Template Sets, Options Template Sets, and other


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         reserved Sets yet to be created.  Template IDs of Data Sets
         are numbered from 256 to 65535.  There are no constraints
         regarding the order of the Template ID allocation.

      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.

   The example in Figure L shows a Template Set with mixed standard and
   enterprise-specific Information Elements. It consists of Set Header,
   Template Header and several Field Specifiers.

       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 = N       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1| Information Element id. 1.1 |        Field Length 1.1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  1.1                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| Information Element id. 1.2 |        Field Length 1.2       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1| Information Element id. 1.N |        Field Length 1.N       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  1.N                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID = 257        |         Field Count = M       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| Information Element id. 2.1 |        Field Length 2.1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1| Information Element id. 2.2 |        Field Length 2.2       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  2.2                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


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      |1| Information Element id. 2.M |        Field Length 2.M       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  2.M                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Padding (opt)                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure L: Template Set Example

   Information Element Identifiers 1.2 and 2.1 are defined by the IETF
   (Enterprise bit = 0) and therefore do not need an Enterprise Number
   to identify them.

 3.4.2   Options Template Record Format

   Thanks to the notion of scope, The Options Template Record gives the
   Exporter the ability to provide additional information to the
   Collector which would not be possible with Flow Records alone.

   One Options Template Record example is the "Flow Keys", which
   reports the Flow Keys for a template, 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.

 3.4.2.1 Scope

   The scope, which is only available in the Options Template Set,
   gives the context of the reported Information Elements in the Data
   Records.  Note that the IPFIX Message Header already contains the
   Source ID (the identifier of the Observation Domain). If not zero,
   this Source ID can be considered as an implicit scope for the Data
   Records in the IPFIX Message.

   Multiple scope fields MAY be present in the Options Template Record,
   in which case, the composite scope is the combination of the scopes.
   For example, if the two scopes are defined as "metering process" and
   "template", the combined scope is this template for this metering
   process.  The order of the scope fields, as defined in the Options
   Template Record, is irrelevant in this case. However, if the order
   of the scope fields in the Option Template Record 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


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

   The scope is an Information Element specified in the IPFIX
   Information Model [IPFIX-INFO].  An IPFIX compliant implementation
   of the Collecting Process SHOULD support this minimum set of
   Information Elements as scope: LineCardId, TemplateId,
   exporterIPv4Address, exporterIPv6Address, and ingressInterface.
   Note that other Information Elements such as meteringProcessId,
   exportingProcessId, sourceId, etc. are also valid scopes.  The IPFIX
   protocol doesn't prevent the use of any Information Elements for
   scope.  However some Information Element types don't make sense if
   specifed as scope.  For example: the counter Information Elements.

   Finally, note that the Scope Field Count MAY NOT be zero.

 3.4.2.2 Options Template Record Format

   An Option Template Record contains any combination of IANA-assigned
   and/or enterprise-specific Information Elements identifiers.

   The format of the Option Template Record is shown in Figure M. It
   consists of a Option Template Record Header and one or more Field
   Specifiers. The definition of the Field Specifiers is given in
   figure G above.

         +--------------------------------------------------+
         | Option Template Record Header                    |
         +--------------------------------------------------+
         | Field Specifier                                  |
         +--------------------------------------------------+
         | Field Specifier                                  |
         +--------------------------------------------------+
          ...
         +--------------------------------------------------+
         | Field Specifier                                  |
         +--------------------------------------------------+

             Figure M: Option Template Record Format


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   The format of the Option Template Record Header is shown in Figure
   N.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Template ID (> 255)   |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Scope Field Count        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure N: Option Template Record Header Format

   The Options Template Record Header Field Definitions are as follows:

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

      Field Count
         Number of all fields in this Option Template Record, including
         the Scope Fields.  Because an Option Template Set usually
         contains multiple Option 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.  The
         Scope Fields are normal Fields except that they are
         interpreted as Scope at the Collector.  The Scope Field Count
         MAY NOT be zero.

   The example in Figure O shows an Option Template Set with mixed IETF
   and enterprise-specific Information Elements.  It consists of Set
   Header, Option Template Header and several Field Specifiers.

      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 = 258     |         Field Count = N + M   |


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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope Field Count = N     |0|  Scope 1 Infor. Element Id. |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope 1 Field Length      |0|  Scope 2 Infor. Element Id. |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope 2 Field Length      |             ...               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            ...                |1|  Scope N Infor. Element Id. |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope N Field Length      |   Scope N Enterprise Number ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ...  Scope N Enterprise Number   |1| Option 1 Infor. Element Id. |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Option 1 Field Length      |  Option 1 Enterprise Number ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ... Option 1 Enterprise Number   |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |0| Option M Infor. Element Id. |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Option M Field Length     |      Padding (optional)       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure O: Option Template Set Example

 3.4.3   Data Record Format

   The Data Records are sent in Data Sets. The format of the Data
   Record is shown in Figure P.  It consists only of one or more Field
   Values.  The Template ID to which the Field Values belong is encoded
   in the Set Header field "Set ID" i.e., "Set ID" = "Template ID".

         +--------------------------------------------------+
         | Field Value                                      |
         +--------------------------------------------------+
         | Field Value                                      |
         +--------------------------------------------------+
          ...
         +--------------------------------------------------+
         | Field Value                                      |
         +--------------------------------------------------+

               Figure P: Data Record Format



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   Note that Field Values do not necessarily have a length of 16 bits.
   Field Values are encoded according to their data type specified in
   [IPFIX-INFO].

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

   The example in Figure Q shows a Data Set. It consists of a Set
   Header several Field Values.

       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 - 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 (optional)       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         Figure Q: Data Set, containing Data Records

 4.     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 Option Template and Option Template Records defined in these
   sub-sections, which impose some constraints on the Metering Process
   and Exporting Process implementations, MAY be implemented.  If
   implemented, the specific Option Templates SHOULD be implemented as
   specified in these sub-sections.



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   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.

 4.1      The Metering Process Statistics Option Template

   The Metering Process Statistics Option Template specifies the
   structure of a Data Record for reporting Metering Process
   statistics.  It SHOULD contain the following Information Elements
   that are defined in [IPFIX-INFO]:

        sourceId                An identifier of an Observation Domain
                                that is locally unique to the Exporting
                                Process.  This Information Element MUST
                                be defined as a Scope Field.

        exportedMessageTotalCount
                                The total number of IPFIX Messages
                                that the Exporting Process successfully
                                sent to the Collecting Process since
                                the Exporting Process re-
                                initialization.

        exportedFlowTotalCount  The total number of Flow Records that
                                the Exporting Process successfully sent
                                to the Collecting Process since the
                                Exporting Process re-initialization.

        exportedOctetTotalCount The total number of octets that the
                                Exporting Process successfully sent to
                                the Collecting Process since the
                                Exporting Process re-initialization.

   The Exporting Process SHOULD export the Data Record specified by the
   Metering Process Statistics Option Template on a regular basis or
   based on some export policy.  This periodicity or export policy
   SHOULD be configurable.

   Note that if several Metering Processes are available on the
   Exporter Observation Domain, the Information Element
   meteringProcessId MUST be specified as an additional Scope Field.




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 4.2      The Metering Process Reliability Statistics Option Template

   The Metering Process Reliability Option Template specifies the
   structure of a Data Record for reporting lack of reliability in the
   Metering Process.  It SHOULD contain the following Information
   Elements that are defined in [IPFIX-INFO]:

        sourceId                An identifier of an Observation Domain
                                that is locally unique to the Exporting
                                Process.  This Information Element MUST
                                be defined as a Scope Field.

        ignoredPacketTotalCount The total number of IP packets that the
                                Metering Process did not process.

        ignoredOctetTotalCount  The total number of octets in observed
                                IP packets that the Metering Process
                                did not process.

        time first ignored      The time stamp of the first IP packet
                                that was ignored by the Metering
                                Process.  For this time stamp, any of
                                the æflowStartÆ time stamp Information
                                Elements flowStartMilliSeconds,
                                flowStartMicroSeconds,
                                flowStartNanoSeconds, and
                                flowStartDeltaUseconds can be used.

        time last ignored       The time stamp of the last IP packet
                                that was ignored by the Metering
                                Process.  For this time stamp, any of
                                the æflowEndÆ time stamp Information
                                Elements flowEndMilliSeconds,
                                flowEndMicroSeconds,
                                flowEndNanoSeconds, and
                                flowEndDeltaUseconds can be used.

   The Exporting Process SHOULD export the Data Record specified by the
   Metering Process Reliability Statistics Option Template on a regular
   basis or based on some export policy.  This periodicity or export
   policy SHOULD be configurable.

   Note that if several Metering Processes are available on the


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   Exporter Observation Domain, the Information Element
   meteringProcessId MUST be specified as an additional Scope Field.

 4.3      The Exporting Process Reliability Statistics Option Template

   The Exporting Process Reliability Option Template specifies the
   structure of a Data Record for reporting lack of reliability in the
   Exporting process.  It SHOULD contain the following Information
   Elements that are defined in [IPFIX-INFO]:

        Exporting Process ID    The identifier of the Exporting Process
                                for which lack of reliability is
                                reported.  There are three Information
                                Elements specified in [IPFIX-INFO] that
                                can be used for this purpose:
                                exporterIPv4Address,
                                exporterIPv6Address, or
                                exportingProcessId.  This
                                Information Element MUST be defined
                                as a Scope Field.

         notSentFlowTotalCount   The total number of Flows that were
                                        generated by the Metering Process and
                                 but dropped by the Metering Process or
                                 by the Exporting Process instead of
                                 sending it to the Collecting Process.

         notSentPacketTotalCount The total number of packets in Flow
                                 Records that were generated by the
                                 Metering Process and but dropped by
                                 the Metering Process or by the
                                 Exporting Process instead of sending
                                 it to the Collecting Process.

         notSentOctetTotalCount  The total number of octets in  packets
                                 in Flow Records that were generated by
                                 the Metering Process and but dropped
                                 by the Metering Process or by the
                                 Exporting Process instead of sending
                                 it to the Collecting Process.

        time first flow dropped The time stamp of the first Flow



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                                was dropped by the Metering
                                Process.  For this time stamp, any of
                                the æflowStartÆ time stamp Information
                                Elements flowStartMilliSeconds,
                                flowStartMicroSeconds,
                                flowStartNanoSeconds, and
                                flowStartDeltaUseconds can be used.

        time last flow dropped  The time stamp of the last IP packet
                                that was ignored by the Metering
                                Process.  For this time stamp, any of
                                the æflowEndÆ time stamp Information
                                Elements flowEndMilliSeconds,
                                flowEndMicroSeconds,
                                flowEndNanoSeconds, and
                                flowEndDeltaUseconds can be used.

   The Exporting Process SHOULD export the Data Record specified by the
   Exporting Process Reliability Statistics Option Template on a
   regular basis or based on some export policy.  This periodicity or
   export policy SHOULD be configurable.

 4.4      The Flow Keys Option Template

   The Flow Keys Option Template specifies the structure of a Data
   Record for reporting the Flow Keys of reported Flows.  A Flow Keys
   Data Record extends a particular Template Record that is referenced
   by its templateId identifier.  The Template Record is extended by
   specifying which of the Information Elements contained in the
   corresponding Data Records describe Flow properties that server as
   Flow Keys of the reported Flow.

   The Flow Keys Option Template SHOULD contain the following
   Information Elements that are defined in [IPFIX-INFO]:

        templateId              An identifier of a Template that
                                locally unique to the Exporting
                                Process.  This Information
                                Element MUST be defined as a Scope
                                Field.

        flowKeyIndicator
                                Bitmap with the positions of the Flow
                                 Keys in the Data Records.


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 5.     IPFIX Message Header "Export Time" and Flow Record Time

   The IPFIX Message Header "Export Time" field is the time in seconds
   since 0000 UTC Jan 1st, 1970, at which the IPFIX Message Header
   leaves the Exporter.  The time-related Information Elements
   specified in [IPFIX-INFO] MAY use this "Export Time" as base time
   and specify an offset relative to it, instead of using a common base
   time, such as 0000 UTC Jan 1st, 1970.  All Information Elements that
   do not have their base time defined by their data type, MUST have
   the base time clearly specified in their description.

   For example, Data Records requiring a microsecond precision can
   export the flow start and end times with the flowStartMicroSeconds
   and flowEndMicroSeconds Information Elements [IPFIX-INFO],
   containing the time since 0000 UTC Jan 1st 1970.  An alternate
   solution is to export the flowStartDeltaUSeconds and
   flowEndDeltaUSeconds Information Elements [IPFIX-INFO] in the Data
   Record, which respectively report the flow start and end time
   offsets compared to the IPFIX Message Header "Export Time".  The
   latter solution lowers the export bandwidth requirement while it
   increases the load on the Exporter as the Exporting Process must
   calculate the flowStartDeltaUSeconds and flowEndDeltaUSeconds of
   every single Data Record before exporting the IPFIX Message.

   It must be noted that using time-related Information Elements with
   offset times compared to the IPFIX Message Header "Export Time"
   imposes some time constraints on the Data Records contained in the
   IPFIX Message.  In the example of flowStartDeltaUSeconds and
   flowEndDeltaUSeconds Information Elements [IPFIX-INFO], the Data
   Record must be exported within a maximum of 71 minutes after its
   creation. Otherwise, the 32-bits counter would not be sufficient to
   contain the flow start time offset.

 6.     Linkage with the Information Model

   The Information Elements [IPFIX-INFO] MUST be sent in canonical
   format in network byte order (also known as the big-endian byte
   ordering).

 6.1      Encoding of IPFIX Data Types

   The following sections will define the encoding of the data types
   specified in [IPFIX-INFO].


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 6.1.1   Integral Data Types

   Integral data types - octet, unsigned16, unsigned32 and unsigned64 -
   are encoded using the default canonical format in network byte
   order.

 6.1.2   Address Types

   Address types - macAddress, ipv4Address and ipv6Address - are
   encoded the same way as the integral data types. The macAddress is
   treated as a 6-octet integer, the ipv4Address as a 4-octet integer
   and the ipv6Address as a 16-octet integer.

 6.1.3   float32

   The float32 data type is encoded as an IEEE single-precision 32-bit
   floating point-type.

 6.1.4   boolean

   The boolean data type is specified according to the TruthValue in
   [RFC2579]: that is an integer with the value 1 for true and a value
   2 for false. Every other value is undefined. The boolean data type
   is encoded in a single octet.


 6.1.5   string and octetarray

   The data type string represents a finite length string of valid
   characters of the Unicode character encoding set.  It is expected
   that strings will be encoded in UTF-8 format.  The string is sent as
   an array of octets using an information element of fixed or variable
   length. The length of the information element specifies the length
   of the octetarray.  In case of fixed length Information Element, if
   padding is required, padding MUST be composed of NUL character(s).


 6.1.6   dateTimeSeconds

   The data type dateTimeSeconds represents a time value having a
   precision of seconds and normalised to the GMT timezone. It is




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   encoded in a 32-bit integer containing the number of seconds since
   0000 UTC Jan 1st 1970.

 6.1.7   dateTimeMilliSeconds

   The data type dateTimeMilliSeconds represents a time value having a
   precision of milliseconds and normalized to the GMT timezone.  It is
   encoded in a 64-bit integer containing the number of milliseconds
   since 0000 UTC Jan 1st 1970.

 6.1.8   dateTimeNanoSeconds

   The data type of dateTimeNanoSeconds represents a time value having
   a precision of nanoseconds and normalized to the GMT timezone.  It
   is encoded in a 64-bit integer according to the NTP format given in
   [RFC1305].  The high-order 32-bits represent the number of seconds
   1900 and the low-order 32-bits represent the fractional seconds with
   the fraction ranging from 0 - 2^(32-1) / 2^32.  This gives a maximum
   precision of about 200 picoseconds.

 6.1.9   dateTimeMicroSeconds

   The data type dateTimeMicroSeconds represents a time value having a
   precision of microseconds and normalized to the GMT timezone.  Its
   encoding is the same as that for dateTimeNanoSeconds, but it may use
   fewer bits in the fractional seconds so as to reflect its lesser
   precision.


 6.2      Reduced Size Encoding of Integer Types

   Information Elements containing integer, string, and octetarray
   types in the information model MAY be encoded using fewer octets
   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 Element definitions
   [IPFIX-INFO] will always define the maximum encoding size.

   For instance the information model [IPFIX-INFO] defines byteCount as
   an unsigned64 type, which would require 64-bits.  However if the
   Exporter will never locally encounter the need to send a value


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   larger than 4294967295, it may chose to send the value instead as an
   unsigned32.  For example, a core router would require an unsigned64
   byteCount while an unsigned32 might be sufficient for an access
   router.

   This behavior is indicated by the Exporter by specifying a type size
   with a smaller length than that associated with the assigned type of
   the Information Element.  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.

 7.     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 255 octets.  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 octets,
   the length is carried in the first octet of the Information Element,
   as shown in Figure R.

       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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      | Length (< 255)|          Information element                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure R: Variable Length Information Element (length < 255 octets)

   If the length of the Information Element is greater than or equal to
   255 octets, the first octet of the Information Element is 255, and
   the length is carried in the second and third octets of the
   Information Element, as shown in Figure S.

       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 S: Variable Length Information Element
               (length 255 to 65535) octets

 8.     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 10.

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

   If a specific Information Element is required by a Template but is
   not available in observed packets, the Exporting Process MAY choose
   to export Flow Records without this Information Element in a Data
   Record defined by a new Template.

   Template 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



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   of the association so that it can interpret the corresponding 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 Set 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 Data Record.  Data Records that
   correspond to a Template Record MAY appear in the same and/or
   subsequent IPFIX Message(s).

   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. Before reusing 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. This time MUST
   be configurable.

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

      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 = 16          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Template ID N        |        Field Count = 0        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Template ID ...      |        Field Count = 0        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Template ID M        |        Field Count = 0        |


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     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure T: 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 withdrawal.
   Multiple Template IDs MAY be withdrawn with a single Template
   Withdrawal Message: in that case, padding MAY be used.

   The Template Withdraw Message withdraws the Template IDs 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 and a new Template definition) 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 Template is changed, a Template
   Withdraw Message MUST be sent to delete the Template.

   When the Exporting Process restarts, due to the SCTP association
   shutdown, 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 U.

      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 U: All Data Templates Withdrawal Message format




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   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 V.

      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 V: All Options Templates Withdrawal Message format

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

 9.     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 10.

   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.

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

   Template 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 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


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   (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 Data Records.  The Data Records
   are then decoded and stored by the Collector. If the Template
   Records have not been received at the time Data Records are
   received, the Collecting Process MAY store the Data Records for a
   short period of time and decode them after the Template Records are
   received.  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 Information Element identifier
   of any Information Element that it does not understand and MAY
   discard that Information Element from the Flow Record.

   The Collector MUST accept padding in Data Records and Template
   Records.

   The IPFIX protocol has a Sequence Number field in the Export header
   which increases with the number of IPFIX Data Records in the IPFIX
   Message.  A Collector may detect out of sequence, dropped, or
   duplicate IPFIX Messages by tracking the Sequence Number.  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 Records
   associated with the specific Exporter and specific Observation
   Domain, and stop decoding IPFIX Messages that use the withdrawn
   Templates.


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   A Collecting Process that receives IPFIX Messages from several
   Observation Domains from the same Exporter MUST be aware that the
   uniqueness of the Template ID is not guaranteed across Observation
   Domains.

 10.      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 65535 octets including the header.  A Collecting
   Process MUST be able to handle IPFIX Message lengths of up to 65535
   octets.

 10.1       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
   avoidance 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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 10.2       SCTP

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

 10.2.1  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.

 10.2.2  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
   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 the IPFIX Messages.  If Data Records are
   discarded the sequence numbers used for export MUST reflect the loss
   of data.

 10.2.3  MTU

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





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 10.2.4  Exporting Process

 10.2.4.1 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 (EDITOR NOTE: to be
   assigned by IANA).  By default the Exporting Process tries to
   connect to this port.  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).

 10.2.4.2 Association Shutdown

   When an Exporting Process is shutdown, 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 of the
   association.

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

   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.

 10.2.4.3 Stream





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   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)
   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, if the queue overflows during times of
   congestion or other retransmission events, 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]
   specification.  The freed buffer space should then be re-used for
   the new Data Sets being exported.

 10.2.4.4 Template Management

   When the transport protocol is SCTP the default Template Management
   described in Section 8 is used.

 10.2.5  Collecting Process

   When the transport protocol is SCTP, the default Collector
   processing described in Section 9 is used.

 10.2.6  Failover




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   If the Collecting Process does not acknowledge the attempt by the
   Exporting Process to establish an association the Exporting Process
   should 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.

 10.3       UDP

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

 10.3.1  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.

 10.3.2  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.
   UDP MUST NOT be used unless the application can tolerate some
   loss of IPFIX Messages.

   The Collecting Process could deduce the loss and reordering of IPFIX
   Data Records by looking at the discontinuities in the IPFIX Message
   sequence number. In the case of UDP, the IPFIX Message sequence
   number contains the total number of IPFIX Data Records received for
   the UDP association, prior to the receipt of this IPFIX Message,
   modulo 2^32. IPFIX sequence number discontinuities 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 Data Records using UDP as the transport protocol.


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 10.3.3  MTU

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

 10.3.4  Port Numbers

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

 10.3.5  Exporting Process

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

 10.3.6  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 multiple copies of the new template definitions, in different
   IPFIX Messages, 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 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 4.4) is sent in
   an Option Template, then the associated Template SHOULD be sent in
   the same IPFIX Message.





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   Following a configuration change that can modify the interpretation
   of the Data Records (for example, a sampling rate change) a new
   Template ID MUST be used and the old Template ID MUST NOT be reused
   until its lifetime (see section 10.3.7) has expired.

   Template Withdraw Messages SHOULD NOT be sent over UDP.

 10.3.7   Collecting Process

   The Collecting Process MUST associate a lifetime with each Template
   received via UDP.  Templates not refreshed by the Exporting Process
   within the lifetime 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 Data Records.  In
   which case, an alarm MUST be logged.  The Collecting Process MUST
   NOT decode any further Data Records which are associated with the
   expired Template.  The Template lifetime at the Collecting Process
   MUST be at least 3 times higher that the Template refresh timeout
   configured on the Exporting Process.

   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 Source ID, Template
   ID, Template Definition, Last Received>.



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


 10.3.8  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



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

 10.4      TCP

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

 10.4.1  Connection Management

 10.4.1.1 Connection Establishment

   The IPFIX Exporting Process initiates a TCP connection to the
   Collecting Process.  By default, the Collecting Process listens for
   connections on TCP port XXXX (EDITOR NOTE: to be assigned by IANA).
   By default the Exporting Process tries to connect to this port.  It
   MUST be possible to configure both the Exporting Process and the
   Collecting Process 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).

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

 10.4.1.2 Graceful Connection Release

   When an Exporting Process is shutdown, it SHOULD shutdown the TCP
   connection.  If TLS [TLS] is used, the Exporting Process SHOULD send
   a close_notify alert before closing the TCP connection.

   When a Collecting Process no longer wants to receive IPFIX messages,
   it SHOULD close its end of the connection.  The Collecting Process
   SHOULD continue to read IPFIX Messages until the Exporting Process
   has closed its end.

 10.4.1.3 Restarting Interrupted Connections

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




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   When an Exporting Process detects that the TCP connection to the
   Collecting Process has terminated abnormally, it SHOULD try to re-
   establish the connection.  Connection timeouts and retry schedules
   SHOULD be configurable.  In the default configuration, an Exporting
   Process MUST NOT attempt to establish a connection more frequently
   than once per minute.

 10.4.1.4 Failover

   If the Collecting Process does not acknowledge the attempt by the
   Exporting Process to establish an connection it will retry using the
   TCP exponential backoff feature.

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

 10.4.2  Data Transmission

   Once a TCP connection is established, and, if configured, TLS [TLS]
   usage has been negotiated, the Exporting Process starts sending
   IPFIX Messages to the Collecting Process.

 10.4.2.1 IPFIX Message Encoding

   IPFIX Messages are sent over the TCP connection without any special
   encoding.  The Length field in the IPFIX Message header defines the
   end of each IPFIX Message and thus the start of the next IPFIX
   Message.  This means that IPFIX Messages cannot be interleaved.

   In the case of TCP, the IPFIX Message sequence number contains the
   total number of IPFIX Data Records received for the TCP connection,
   prior to the receipt of this IPFIX Message, modulo 2^32.

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

 10.4.2.2 Templates

   For each template, the Exporting Process MUST send the Template
   Record before exporting Data Records that refer to that template.


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   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.

   When the TCP connection restarts, the Exporting Process MUST resend
   all the Template Records.

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

 10.4.2.3 Congestion Handling and Reliability

   TCP ensures reliable delivery of data from the Exporting Process to
   the Collecting Process.  TCP also controls the rate at which data
   can be sent from the Exporting Process to the Collecting Process,
   using a mechanism that takes into account both congestion in the
   network and the capabilities of the receiver.

   Therefore an IPFIX Exporting Process may not be able to send IPFIX
   Messages at the rate that the Metering Process generates it, either
   because of congestion in the network or because the Collecting
   Process cannot handle IPFIX Messages fast enough.  As long as
   congestion is transient, the Exporting Process can buffer IPFIX
   Messages for transmission.  But such buffering is necessarily
   limited, both because of resource limitations and because of
   timeliness requirements, so ongoing and/or severe congestion may
   lead to a situation where the Exporting Process is blocked.

   When an Exporting Process has Data Records to export but the
   transmission buffer is full, and it wants to avoid blocking, it can
   decide to drop some Data Records.  The dropped Data Records MUST be
   accounted for, so that the amount can later be exported.

   When an Exporting Process finds that the rate at which records
   should be exported is consistently higher than the rate at which TCP
   sending permits, it should provide back pressure to the metering
   processes.  The metering process could then adapt by temporarily
   reducing the amount of data it generates, for example using sampling
   or aggregation.




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 11.      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 Data
   Records or Template Records.  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.

 11.1       IPsec Usage

   To secure messages between the Exporter and the Collector an IPFIX
   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].

 11.1.1  Selectors

   IPFIX runs between manually configured pairs of hosts on the
   following transport ports (EDITOR NOTE: to be assigned by IANA).
   The appropriate selector would be Exporter-Collector pairs and port



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   number.

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

 11.1.2  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 only ESP is used, the sender's IP address MUST be
   checked against the IP address asserted in the key management
   exchange.

 11.1.3  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 the IKE [IKE] key management system SHOULD be used.

 11.1.4  Security Policy

   Connections should be accepted only from designated peers.

 11.1.5  Authentication

   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.

 11.1.6  Availability

   It is accepted that IPsec will not be universally available in IPFIX



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   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.

 11.2       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
   Collector MUST request a certificate from the Exporter, and the
   Exporter MUST be prepared to supply a certificate on request.

 11.3       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.

 11.4       When IPsec or TLS is not an option

   The use of IPsec or TLS might not be possible in certain cases due
   to performance issues.

   Without IPsec or TLS the only way that an IPFIX Exporter, proxy or
   Collector can authenticate each other is by inspecting the IP source
   address of the packets carrying the IPFIX Messages and their



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   transport acknowledgments.  Useful protection is gained by
   allocating Exporter and Collector IP addresses from ranges that are
   excluded from use by user traffic and hence preventing spoofing
   attacks by ingress packet 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.  The use of 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 [RFC1948] or SCTP
   insertion such attacks are difficult without the ability to snoop
   the packet Flow [RFC2960].  UDP is vulnerable to insertion attacks,
   and SHOULD be protected by the use of the address restriction
   mechanism described above.

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

 11.5       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 resets the expected Sequence Number upon
   receipt of a later message would easily be temporarily blinded by
   deliberately injecting messages with a much larger Sequence Number.

 12.      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].





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 12.1       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.

 12.2       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
   Information Element type is indicated by its Information Element
   identifier.

   New assignments for IPFIX Information Elements will be administered
   by IANA, on a First Come First Served 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 with already defined Information Elements for
   completeness, accuracy and redundancy.  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
   Information Elements will range from 128 to 32767; the values below
   128 are reserved or already assigned.

 13.      Examples

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

   IPFIX Message:

   +--------+------------------------------------------. . .



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

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

 13.1       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                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 13.2       Template Set Examples

 13.2.1  Template Set using IETF specified Information Elements

   We want to report the following Information Elements:

   - The IPv4 source IP address: sourceIPv4Address in [IPFIX-INFO],
   with a length of 4 octets
   - The IPv4 destination IP address: destinationIPv4Address in [IPFIX-
   INFO], with a length of 4 octets





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   - The next-hop IP address (IPv4): ipNextHopIPv4Address in [IPFIX-
   INFO], with a length of 4 octets

   - The number of packets of the Flow: inPacketDeltaCount in [IPFIX-
   INFO], with a length of 4 octets

   - The number of octets of the Flow: inOctetDeltaCount in [IPFIX-
   INFO], with a length of 4 octets

   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 octets       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Template ID 256         |       Field Count = 5         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|    sourceIPv4Address = 8    |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0| destinationIPv4Address = 12 |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|  ipNextHopIPv4Address = 15  |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|   inPacketDeltaCount = 2    |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|   inOctetDeltaCount =  1    |       Field Length = 4        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 13.2.2  Template Set using Enterprise Specific Information Elements

      We want to report the following Information Elements:

      - The IPv4 source IP address: sourceIPv4Address in [IPFIX-INFO],
        with a length of 4 octets

      - The IPv4 destination IP address: destinationIPv4Address in
        [IPFIX-INFO], with a length of 4 octets

      - An enterprise-specific Information Element representing
        proprietary information, with a type of 15 and a length of 4



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      - The number of packets of the Flow: inPacketDeltaCount in
        [IPFIX-INFO], with a length of 4 octets

      - The number of octets of the Flow: inOctetDeltaCount in
        [IPFIX-INFO], with a length of 4 octets

    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 = 32 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID 257         |       Field Count = 5         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|    sourceIPv4Address = 8    |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationIPv4Address = 12 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1| Information Element Id. = 15|       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Enterprise number                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   inPacketDeltaCount = 2    |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   inOctetDeltaCount = 1     |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 13.3       Data Set Example

   In this example, we report the following three Flow Records:

   Src IP addr. | Dst IP addr.  | Next Hop addr. | Packet | Octets
                |               |                | Number | Number
   ------------------------------------------------------------------
   198.18.1.12  | 198.18.2.254  | 198.18.1.1     | 5009   | 5344385
   198.18.1.27  | 198.18.2.23   | 198.18.1.2     | 748    | 388934
   198.18.1.56  | 198.18.2.65   | 198.18.1.3     | 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          |


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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.1.12                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.2.254                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.1.1                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             5009                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            5344385                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.1.27                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.2.23                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.1.2                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              748                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             388934                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.1.56                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.2.65                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.18.1.3                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               5                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              6534                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Note that padding is not necessary in this example.

 13.4       Options Template Set Examples

 13.4.1  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 Information Elements:

      - Total number of IPFIX Messages: exportedPacketCount
        [IPFIX-INFO], with a length of 2 octets


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      - Total number of exported Flows: exportedFlowCount [IPFIX-INFO],
        with a length of 2 octets

   The line card, which is represented by the lineCardId Information
   Element [IPFIX-INFO], is used as the Scope Field.

   Therefore, the Options Template Set will be:

    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 258         |        Field Count = 3        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Scope Field Count = 1     |0|     lineCardId = 141        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Scope 1 Field Length = 4    |0|  exportedPacketCount = 41   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 2        |0|   exportedFlowCount = 42    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 2        |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 13.4.2  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 Information Elements:

     - Total number of IPFIX Messages: exportedPacketCount
       [IPFIX-INFO], with a length of 2 octets

     - An enterprise-specific number of exported Flows,
       with a type of 42 and a length of 4 octets

   The line card, which is represented by the lineCardId Information
   Element [IPFIX-INFO], is used as the Scope Field.

   The format of the Options Template Set is as follows:

       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 = 28          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID 259         |        Field Count = 3        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Scope Field Count = 1     |0|     lineCardId = 141        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Scope 1 Field Length = 4    |0|  exportedPacketCount = 41   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Length = 2        |1|Information Element Id. = 42 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Field Length = 4        |       Enterprise number     ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ...      Enterprise number      |           Padding             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 13.4.3  Options Template Set using an enterprise-specific scope

   In this example, we want to export the same information as in the
   example in section 13.4.1:

      - Total number of IPFIX Messages: exportedPacketCount
        [IPFIX-INFO], with a length of 2 octets

      - Total number of exported Flows: exportedFlowCount
        [IPFIX-INFO], with a length of 2 octets

   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 260         |        Field Count = 3        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Scope Field Count = 1     |1|Scope 1 Infor. El. Id. = 123 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


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                   IPFIX Protocol Specification               May 2005


   |                      Enterprise Number                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Scope 1 Field Length = 4    |0|  exportedPacketCount = 41   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 2        |0|   exportedFlowCount = 42    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 2        |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


 13.4.4  Data Set using an enterprise-specific scope

   In this example, we report the following two Data Records:

   Line Card ID               | IPFIX Message  | Exported Flow Records
   -------------------------------------------------------------------
   Line Card 1 (lineCardId=1) | 345            | 10201
   Line Card 2 (lineCardId=2) | 690            | 20402

     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 = 260             |         Length = 20           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                               1                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |             345               |            10201              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                               2                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |             690               |            20402              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 14.     References

 14.1      Normative References

   [IPFIX-ARCH] Sadasivan, G., Brownlee, N., Claise, B., Quittek, J.,
   "Architecture Model for IP Flow Information Export" draft-ietf-
   ipfix-arch-09.txt", May 2005






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                   IPFIX Protocol Specification               May 2005


   [IPFIX-INFO] Quittek, J., Bryant S., Claise, B., Meyer, J.
   "Information Model for IP Flow Information Export" draft-ietf-ipfix-
   info-07, May 2005

   [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

   [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

 14.2      Informative References

   [RFC3917] Quittek, J., Zseby, T., Claise, B., Zander, S.,
   "Requirements for IP Flow Information Export" RFC 3917, October 2004

   [IPFIX-AS] Zseby, T., Boschi, E., Brownlee, N., Claise, B., "IPFIX
   Applicability", draft-ietf-ipfix-as-05.txt, May 2005

   [RFC3955] Leinen, S., "Evaluation of Candidate Protocols for IP Flow
   Information Export (IPFIX)", RFC 3955, October 2004

   [RFC3954] Claise, B., et al "Cisco Systems NetFlow Services Export
   Version 9", RFC 3954, October 2004



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                   IPFIX Protocol Specification               May 2005


   [RFC2579] McCloghrie, K., et al "Textual Conventions for SMIv2", RFC
   2579, April 1999

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

   [USEIPSEC] Bellovin, S., 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.

   [RFC1948]  Bellovin, S., " Defending Against Sequence Number
              Attacks", RFC 1948, May 1996

 15.      Acknowledgments

   We would like to thank the following persons: Juergen Quittek for
   the coordination job within IPFIX and PSAMP; Nevil Brownlee, Dave
   Plonka, and Paul Aitken for the thorough reviews; Randall Stewart
   and Peter Lei for their SCTP expertise; Martin Djernaes for the
   first essay on the SCTP section; Mark Fullmer, Sebastian Zander,
   Jeff Meyer, Maurizio Molina, Carter Bullard, Tal Givoly, Lutz Mark,
   David Moore, Brian Trammell, Robert Lowe, Paul Calato, and many
   more, for the technical review and 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,



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                   IPFIX Protocol Specification               May 2005


   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

   Simon Leinen
   SWITCH
   Limmatquai 138
   P.O. Box
   CH-8021 Zurich
   Switzerland
   Phone: +41 1 268 1536
   EMail: simon@switch.ch

   Thomas Dietz
   NEC Europte Ltd.
   Network Laboratories
   Kurfuersten-Anlage 36
   69115 Heidelberg
   Germany
   Phone: +49 6221 90511-28
   Email: dietz@netlab.nec.de

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  Claise, et. al            Standard Track                   [Page 61]

                   IPFIX Protocol Specification               May 2005


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   except as set forth therein, the authors retain all their rights.

Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.








  Claise, et. al            Standard Track                   [Page 62]


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