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   IPFIX working group
   Internet Draft                               EDITORS:      B. Claise
   draft-ietf-ipfix-protocol-02.txt                       Cisco Systems
   Expires: July 2004                                      Mark Fullmer
                                                                 OARnet
                                                            Paul Calato
                                                    Riverstone Networks
                                                         Reinaldo Penno
                                                        Nortel Networks
                                                           January 2003


                       IPFIX Protocol Specifications



 Status of this Memo

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

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

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

 Abstract

   This document discusses the IPFIX protocol that provides network
   administrators with access to IP flows information. This document
   focuses on how IPFIX flow record data, options record data and
   control information is carried (via a congestion-aware transport
   protocol) from IPFIX exporting process to IPFIX collecting process.


 Conventions used in this document





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   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.

 Table of Contents

     1. Points of Discussion.........................................3
      1.1 Open Issues................................................3
      1.2 Action Items...............................................5
     2. Introduction.................................................5
      2.1 Overview...................................................5
     3. Terminology..................................................6
      3.1 Terminology Summary Table.................................10
     4. The Metering Process........................................11
      4.1 Flow Expiration...........................................11
     5. Transport Protocol..........................................12
      5.1 TCP.......................................................12
      5.2 STCP......................................................12
     5.2.1   Congestion Avoidance...................................12
     5.2.2   Reliability............................................12
     5.2.3   Exporting Process......................................13
     5.2.3.1  MTU size..............................................13
     5.2.3.2  Source ID.............................................13
     5.2.3.3  Association...........................................13
     5.2.3.4  Stream................................................14
     5.2.3.5  Template..............................................14
     5.2.4   Collecting Process.....................................14
     5.2.5   SCTP Partially Reliable................................15
     6. Failover....................................................16
      6.1 Simple Failover based on the transport protocol...........16
      6.2 Something else?...........................................16
     7. Message Layout..............................................16
     8. IPFIX Message Format........................................18
      8.1 Header Format.............................................18
      8.2 Field Type Format.........................................19
      8.3 Template FlowSet Format...................................20
     8.3.1   IETF Exclusive Template FlowSet Format.................20
     8.3.2   Vendor Specified Template FlowSet Format...............22
      8.4 Data FlowSet Format.......................................24
     9. Options.....................................................25
      9.1 Options Template FlowSet Format...........................25
     9.1.1   IETF Exclusive Options Template FlowSet Format.........25
     9.1.2   Vendor Specified Options Template FlowSet Format.......27
      9.2 Options Data Record Format................................29
      9.3 Specific IPFIX Options Templates..........................30
     9.3.1   The Metering Process Statistics Option Template........31
     10. Export Packet UNIX Secs Computation and Flow Record Times..31
      10.1 Microsecond Precision....................................31
      10.2 Millisecond Precision....................................32


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      10.3 Nanosecond Precision.....................................33
      10.4 Multiple Precisions......................................33
     11. Linkage with the Information Model.........................33
      11.1 Boolean..................................................33
      11.2 Byte.....................................................34
      11.3 UnsignedByte.............................................34
      11.4 Short....................................................34
      11.5 Reduced Size Encoding of Integral Types..................34
     12. Variable Length Data Type..................................35
     13. Template Management........................................36
     14. The Collecting Process's Side..............................37
     15. Security Considerations....................................39
     16. IANA Considerations........................................43
     17. Examples...................................................43
      17.1 Message Header Example...................................44
      17.2 Template FlowSet Example.................................44
      17.3 Data FlowSet Example.....................................45
      17.4 Options Template FlowSet Example.........................46
      17.5 Data FlowSet with Options Data Records Example...........46
     18. References.................................................47
      18.1 Normative References.....................................47
      18.2 Informative References...................................47
     19. Acknowledgments............................................48


 1.  Points of Discussion

 1.1 Open Issues

   This section covers the open issues, still to be resolved/updated in
   this draft:

   - The proposal on the table is to send a IPFIX Sync (this would be
   an Options Data Records) message periodically (periodicity is
   configurable), with the following information (aside the standard
   IPFix header)
           * Number of flow records sent (for each template?)
           * Packets and bytes sent (for each template?)
     Question: Per observation domain?
     Question: Do we need a specific FlowSet ID?
   - Template don't need lifetimes with connection oriented protocol.
   We guess this is the consensus from the Working Group.
   The section 11 "Template Management" will have to updated according
   to the transport protocol. For example, the point 2 of the section
   11 "Template Management"




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   - No periodic retransmission of templates is needed, with a reliable
   transport protocol.
   Remark: the template management will vary with TCP, SCTP, etcà
   Must have both sections updated: transport updated and template
   management sections (BTW, this is the same for the failover
   section).
   - Export ID (ie IP address of exporter) sent to the collector. This
   can be done once with an options template.
   - Metering process stats: for example packets / flows dropped at the
   metering process due to resource exhaustion, etcà This can be done
   with an options template.
   - Error recovery, for example what to do if a collector receives a
   message it can't decode. Per protocol issue, ie TCP reset the
   session because it's a stream protocol and can't recover.
   - If we tackle reliability a state diagram is needed.
   - Talk a little bit about extensibility, for example make some
   decisions now about the reserved template ID's 2-254 for future
   work.
   - Abstract. This document "specifies" + expand it
   - Must develop a Security Section
   - IANA considerations section to be expanded.
   - Potentially some discrepancies between data types, field type and
   Information Element terminology.
   - Need an example with the Vendor Specified Information Element
   - Review the requirements draft to see what we miss, once it's an I-
   RFC
   - Templates identified by FLowset IDs, 0 => 'template,' 1 =>
   'options template,' [2,255] => reserved,  [256 ) => 'data template.'
   Need to specify this (and mechanism for defined other 'well-known'
   values in IANA Considerations section (not yet written).
   - Section 5.2.3.3, Association: What happens if the Exporter gets no
   response from any Collector?  I think we should specify a (not-too-
   aggressive) retry algorithm.
   - æætransport protocolÆÆ section to be updated.
   Note: each transport protocol (TCP/SCTP) should have at least the
   following subsections: Reliability, Failover, Template Management
   Bert Wijnen is currently working on this issue:
   http://
       ipfix.doit
             .wisc.edu/archive/2336.html
   - Nevil comment: Section 10: Variable Length Data Type: Surely this
   really belongs in the Info Model I-D? The Info Model I-D defines the
   'string' data type as "finite length string of valid characters .."
   It needs to say something about whether the length is fixed or



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   variable.  Seems to me that making all strings be variable-length
   would be fine.
   - IANI considerations section to be updated: have a look at RFC
   2434, which sets out guidelines for IANA Considerations. Also,
   searching the RFCs for 'IANA Considerations' brings up quite a few
   RFCs to look at as models.
   - Flow Sampling.  This is mentioned in both the Requirements I-D and
   the AS I-D.  We need to decide how it should be covered in the IPFIX
   drafts.
   - Section 11.4 must be completed with type used in [IPFIX-INFO]
   - Protocol Extensions must be discussed in the draft
   - Need a consensus/discussion on section 9.3.1 "The Metering Process
   Statistics Option Template". The [IPFIX-INFO] needs also the
   appropriate data types

 1.2 Action Items

   This section covers the action items for this draft
   -  4.1 Flow Expiration -> add the notion of integers versus
   counters, after minneapolis WG consensus
   - Use of MUST/SHOULD vs must/should: this is a Standards Track
   draft, there are lots of places I think RFC 2119 (upper case) would
   be more appropriate, starting with section 5.2.3.1. (Most of these
   would be simple 'editing' changes).
   -  9.2 Options Data Record Format
   The Options Data Records are sent in Data FlowSets, on a regular
   basis, but not with every Flow Data Record. How frequently these
   Options Data Records are exported is configurable. See the Templates
   Management" section for more details.
          -> not the right section + expand


    - check the examples with the information model
   - I received the comment to number all the figures

 2. Introduction

 2.1 Overview

   The IPFIX protocol provides network administrators with access to IP
   flows information. The architecture for the export of measured IP
   flow information out of an IPFIX exporting process to a collecting
   processing is defined in [IPFIX-ARCH], per the requirements defined
   in [IPFIX-REQ]. [IPFIX-PROTO] specifies how IPFIX flow record data,
   options record data and control information is carried via a



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   congestion-aware transport protocol from IPFIX exporting process to
   IPFIX collecting process. IPFIX has a formal description of IPFIX
   information elements (fields), their name, type and additional
   semantic information, as specified in [IPFIX-INFO]. Finally [IPFIX-
   AS] describes what type of applications can use the IPFIX protocol
   and how they can use the information provided. It furthermore shows
   how the IPFIX framework relates to other architectures and
   frameworks.

 3. Terminology

   The definitions of IP Traffic Flow, Metering Process, Exporting
   Process and Collecting Process are the definitions as found in the
   IPFIX requirement document [IPFIX-REQ]. Note nevertheless that,
   even if the Observation Point definition has been also been
   completely copied over from the IPFIX requirement document [IPFIX-
   REQ], this definition has been expanded.

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

 Observation Point

   The Observation Point is a location in the network where IP packets
   can be observed. Examples are 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.
   An Observation Domain is associated with every Observation Point.

   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

   The set of Observation Points, which is the largest aggregatable set
   of Flow information at the Metering Process is termed an Observation
   Domain. Each Observation Domain presents itself as a unique ID to
   the Collecting Process for identifying the IPFIX Messages it
   generates.
   For example, a router line card composed of several interfaces with
   each interface being an Observation Point.



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 IP Traffic Flow or Flow

   There are several definitions of the term 'flow' being used by the
   Internet community. Within this document we use the following one:

   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 with a specific sequence
   number. Please note that the Flow definition does not necessarily
   match a general application-level end-to-end stream. However, an
   application may derive properties of application-level streams by
   processing measured Flow data. Also, please note that although
   packet properties may depend on application headers, there is no
   requirement defined in this document related to application headers.

 Flow Record

   A Flow Record provides information about an IP Traffic Flow observed
   at an Observation Point.

 Metering Process

   The Metering Process generates Flow Records. Input to the process
   are packet headers observed at an Observation Point and packet


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   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.

   The sampling function and the classifying function may be applied
   more than once with different parameters. Figure 1 shows the
   sequence in which the functions are applied. Sampling is not
   illustrated in the figure, it may be applied before any other
   function.

                              packet header capturing
                                        |
                                   timestamping
                                        |
                                        v
                                 +----->+
                                 |      |
                                 | classifying
                                 |      |
                                 +------+
                                        |
                             maintaining Flow Records
                                        |
                                        v


                    Figure 1: Functions of the Metering Process

 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.

 Collecting Process



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   The Collecting Process receives Flow Records from one or more
   Exporting Processes. The Collecting Process might store received
   Flow Records or further process them, but these actions are out of
   the scope of this document.

 IPFIX Message

   An IPFIX Message is a message originating at the Exporting Process
   that carries the Flow Records of this Exporting Process and whose
   destination is the Collecting Process.

 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 Flow Data Record.

 Flow Data Record

   A Flow Data Record is a data record that contains values of the Flow
   parameters corresponding to a Template Record. In this document, the
   Flow Data Record is also referred to as Flow Record.

 Options Template Record

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

 Options Data Record

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

 FlowSet





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   FlowSet is a generic term for a collection of records that have a
   similar structure. In an IPFIX Message, one or more FlowSets follow
   the Message Header.
   There are three different types of FlowSets: Template FlowSet,
   Options Template FlowSet, and Data FlowSet.

 Template FlowSet

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

 Options Template FlowSet

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

 Data FlowSet

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

 Information Element

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


 3.1 Terminology Summary Table

         FlowSet        Template  Record        Data Record
   +----------------------------------------------------------------+
   |                  |                    |  Flow Data Record(s)   |
   | Data FlowSet     |          /         |          or            |
   |                  |                    | Options Data Record(s) |
   +----------------------------------------------------------------+
   | Template FlowSet | Template Record(s) |           /            |



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   +----------------------------------------------------------------+
   | Options Template | Options Template   |           /            |
   | FlowSet          | Record(s)          |                        |
   +----------------------------------------------------------------+

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

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

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

 4. The Metering Process

   The description of the Metering Process (for example, sampled or
   not, aggregation or not), which is the way in which Flows are
   created from the observed IP packets, is beyond the scope of this
   document. Nevertheless, some aspects of the Metering Process have
   some influences on the IPFIX protocol

 4.1 Flow Expiration

   A Flow is considered to be inactive if no packets belonging to the
   Flow have been observed at the Observation Point for a given
   timeout. If any packet is seen within the timeout, the flow is
   considered an active Flow.
   A Flow can be exported under the following conditions:

      1. If the Metering Process can detect the end of a Flow. For
      example, if the FIN or RST bit is detected in a TCP [TCP]
      connection, the Flow Record is exported.

      2. If the Flow has been inactive for a certain period of time.
      This inactivity timeout SHOULD be configurable at the Metering
      Process, with a minimum value of 0 for an immediate expiration.

      3. For long-lasting Flows, the Exporting Process SHOULD export
      the Flow Records on a regular basis. This timeout SHOULD be
      configurable at the Metering Process.



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      4. If the Metering Process experiences internal constraints, a
      Flow MAY be forced to expire prematurely; for example, counters
      wrapping or low memory.

 5. Transport Protocol

   The IPFIX Protocol Specifications have been designed to be transport
   protocol independent. It can operate over congestion-aware protocols
   such as TCP [TCP] or SCTP [RFC2960].

   Note that the Exporter can export to multiple Collecting Processes,
   using independent transport protocols.

 5.1 TCP

   To be completed.
   TCP [TCP]

 5.2 STCP

   This section describes how IPFIX can be transported over SCTP
   [RFC2960] using traditional reliable mode.

   IPFIX can also be transported over the partial reliable or
   unreliable mode [PR-SCTP]. These last 2 modes will be briefly
   discussed, while waiting for [PR-SCTP] to become a standard.

 5.2.1    Congestion Avoidance

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

 5.2.2    Reliability

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

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



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   amount of retransmissions are needed, the send queues on the
   Exporting Process may fill up. In that case it's up to the Exporting
   Process to decide what to do. It may either halt export (buffer the
   data until there is space in the send queues again) or discard IPFIX
   Messages away instead of inserting them into the send queue. If any
   data is not inserted into the send queues, the sequence numbers used
   for export must reflect the loss of data.

 5.2.3    Exporting Process

 5.2.3.1  MTU size

   Each IPFIX Message should be equal to or less than the local MTU in
   size. When an IPFIX Message is transmitted over a network with an
   MTU smaller than the local MTU, IP fragmentation may be used.

 5.2.3.2 Source ID

   The IPFIX Message must contain a Message Header, which includes a
   source id (SID). The SID indicates from which Observation Domain the
   data is being exported, and should be kept unique for each such
   Observation Domain.

   If a Metering Process consists of a single Observation Domain, a
   single SID value must be used for all IPFIX Messages. The Exporting
   Process will typically open one association to the collector, but
   more are possible, in which one or more streams can be used. The
   Exporting Process has the choice of transmitting parts of the export
   data in separate streams or all data in one stream.

   If a Metering Process consists of multiple Observation Domains, one
   SID value for each Observation Domain must be used. The Exporting
   Process will typically open one association, but more are possible,
   in which at least one stream per Observation Domain is used.

   The Exporting Process has the choice of using more than one stream
   per Observation Domain, but data from multiple Observation Domains
   should not be transmitted over the same stream.

 5.2.3.3  Association

   The Exporting Process may create one or more associations



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   (connection "bundle" in SCTP terminology) to the Collecting Process.
   The Collecting Process may not initiate the connection. Inside each
   association one or more streams may be requested by the Exporting
   Process. If the Collecting Process can not support the requested
   number of streams, it may choose to refuse the connection and the
   Exporting Process should try to reduce, if possible, the number of
   streams needed to perform the export.

 5.2.3.4  Stream

   An Observation Domain must use at least one stream, but may use
   multiple streams, to export data records. The Observation Domain
   must use the same SID value for all streams used.

   An Exporting Process must not transmit messages with different SID
   values in one stream, the Collecting Process should however verify
   that the SID values are the expected values.

 5.2.3.5  Template

   Since the SCTP association is connection oriented the available
   Template Records must be transmitted from each Observation Domain to
   the Collecting Process immediately after the association is
   established.

   As a minimum the Template Records must be transmitted immediately
   after they start to exist on the Metering Process and should
   preferably be transmitted before any data, using the new Template
   Record, have been transmitted. The Collecting Process should however
   accept data without a Template Record.

   When using a reliable mode for Template Record export, or if the
   exporter knows that the IPFIX Message containing the templates was
   positively acknowledged by the SCTP layer, it is not necessary to
   periodically export the Template Records.

 5.2.4    Collecting Process

   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. If the Collecting Process
   doesn't support the number of streams inside the association, the



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   Collecting Process must refuse the connection and continue listen
   for a new request.

   When data is received from an association, the Collecting Process
   must correlate data, with the same SID (Source ID) value, from
   multiple streams into one export Flow from an Observation Domain.
   This allows the Observation Domain to use separate streams for
   different types of
   information.

   The Collecting Process should verify that the received IPFIX
   Messages inside one stream does not have differing SID values. The
   Exporting Process must not transmit messages inside one stream with
   multiple SID values. The correlated Flow Records are then treated
   like a normal export Flow.

 5.2.5    SCTP Partially Reliable

   This mode will not be discussed any further until [PR-SCTP] becomes
   a standard, even if this mode offers a few advantages:
   freedom to use SCTP as a reliable, single stream transport, as well
   as multiple streams with different properties, for example in terms
   of reliability, carrying different data types dependant on their
   importance for the system.
   Unreliable or partial reliability may be chosen for one or more
   streams inside an association. Unreliable transport may be preferred
   where large amount of data is to be exported and keeping send queues
   is either an unnecessary overhead or impractical. Partial
   reliability may be chosen where a small amount of queuing is
   possible.

   Naturally it is better to send templates over a reliable stream and
   send the data on an unreliable (or partial reliable) stream. When an
   exporter handles data with different properties it might even be
   preferable to send them over different streams according to those
   properties.

   Example: an Exporting Process can use two streams per Observation
   Domain. A reliable stream could be used for exporting templates, to
   reduce the likelihood of loss and to remove the need for blind
   retransmissions, and a partial or unreliable stream for data, to
   avoid buffering of large amounts of data.



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 6. Failover

   When to fail over?
   How to fail back?
   How to ensure stability of the failover mechanism (prevent
   oscillations)?
   Does the exporter open connections to all the potential collectors
   and keep them primed with template info?

 6.1 Simple Failover based on the transport protocol

   In case the transport protocol is connection oriented.
   So in case of TCP [TCP] or SCTP [RFC2960].
   To be completed.

 6.2 Something else?

   Potentially based on some application level ACK from the exporter?

 7. Message Layout

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

   IPFIX Message:
   +--------+-------------------------------------------+
   |        | +----------+ +---------+ +----------+     |
   |Message | | Template | | Data    | | Options  |     |
   | Header | | FlowSet  | | FlowSet | | Template | ... |
   |        | |          | |         | | FlowSet  |     |
   |        | +----------+ +---------+ +----------+     |
   +--------+-------------------------------------------+

   A FlowSet ID is used to distinguish the different types of FlowSets.
   FlowSet IDs lower than 256 are reserved for special FlowSets, such
   as the Template FlowSet (ID 0) and the Options Template FlowSet (ID
   1). The Data FlowSets have a FlowSet ID greater than 255.

   The format of the Template, Data, and Options Template FlowSets will
   be discussed later in this document. The Exporter MUST code all
   fields of the different FlowSets in network byte order (big-endian).



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   Following are some examples of IPFIX Messages:

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

   IPFIX Message:
   +--------+--------------------------------------------------------+
   |        | +----------+ +---------+     +-----------+ +---------+ |
   |Message | | Template | | Data    |     | Options   | | Data    | |
   | Header | | FlowSet  | | FlowSet | ... | Template  | | FlowSet | |
   |        | |          | |         |     | FlowSet   | |         | |
   |        | +----------+ +---------+     +-----------+ +---------+ |
   +--------+--------------------------------------------------------+

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

   IPFIX Message:
   +--------+----------------------------------------------+
   |        | +---------+     +---------+      +---------+ |
   |Message | | Data    | ... | Data    | ...  | Data    | |
   | Header | | FlowSet | ... | FlowSet | ...  | FlowSet | |
   |        | +---------+     +---------+      +---------+ |
   +--------+----------------------------------------------+

   3. An IPFIX Message consisting entirely of Template and Options
   Template FlowSets-The Exporter MAY transmit a message containing
   Template and Options Template FlowSets periodically to help ensure
   that the Collecting Process has the correct Template Records and
   Options Template Records when the corresponding Flow Data records
   are received.

   IPFIX Message:
   +--------+-------------------------------------------------+
   |        | +----------+     +----------+      +----------+ |
   |Message | | Template |     | Template |      | Options  | |
   | Header | | FlowSet  | ... | FlowSet  | ...  | Template | |


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   |        | |          |     |          |      | FlowSet  | |
   |        | +----------+     +----------+      +----------+ |
   +--------+-------------------------------------------------+

 8. IPFIX Message Format

 8.1 Header Format

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Version Number          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           sysUpTime                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           UNIX Secs                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Sequence Number                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Source ID                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   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 FlowSet(s).

   sysUpTime
           Time in milliseconds since this device was first booted.

   UNIX Secs
           Time in seconds  since 0000 UTC 1970, at which the Export
           Packet leaves the Exporter.

   Sequence Number
           Incremental sequence counter of all IPFIX Messages sent from
           the current Observation Domain by the Exporting Process.
           This value MUST be cumulative, and SHOULD be used by the


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           Collector to identify whether any IPFIX Messages have been
           missed.

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


 8.2 Field Type Format

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

   The Field Ids used to identify Information Elements are divided into
   two non-overlapping ranges: the IETF specified range and the vendor
   specified range. This partitioning of the identifiers into two
   ranges allows the Collecting Process to discriminate between an IETF
   specified Information Element and a Vendor Specified Information
   Element. The vendor specified range is shared by all vendors, and
   thus needs an accompanying vendor identifier to uniquely identify
   it.

   The format of an IETF defined Field Type is shown in Fig A.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Field Type            |         Field Length          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Fig A: IETF defined Field Type

      Where:

      Field Type
         A numeric value that represents the type of the field. Refer


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         to [IPFIX-INFO].

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

   The format of the Vendor Specified Field Type is shown in Fig B.

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

      Fig B: Vendor Specified Field Type

      Where:

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

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

      Enterprise Number
         IANA enterprise number [PEN] of the authority defining the
         field type in this template record.

 8.3 Template FlowSet Format

   One of the essential elements in the IPFIX format is the Template
   FlowSet. Templates greatly enhance the flexibility of the Flow
   Record format because they allow the Collecting Process to process
   Flow Records without necessarily knowing the interpretation of all
   the data in the Flow Record.

 8.3.1    IETF Exclusive Template FlowSet Format




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   The IETF exclusive Template FlowSet MAY be used when the template
   contains only IETF defined Information Elements. This format is
   provided for backwards compatibility [NETFLOW9]. The format of the
   IETF exclusive Template FlowSet is shown in Figure C.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       FlowSet ID = 0          |          Length               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID 1           |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 1           |         Field Length 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 2           |         Field Length 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type N           |         Field Length N        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID 2           |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 1           |         Field Length 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 2           |         Field Length 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type M           |         Field Length M        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Template ID K          |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure C: IETF Exclusive Template FlowSet Format
                     Field Descriptions

     FlowSet ID
           FlowSet ID value of 0 is reserved for the Template FlowSet.



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

     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 FlowSets,
           Options FlowSets, and other reserved FlowSets yet to be
           created. Template IDs of Data FlowSets are numbered from 256
           to 65535.

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

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

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

 8.3.2    Vendor Specified Template FlowSet Format

   A vendor specified Template FlowSet MUST be used when the template
   contains one or more Vendor Specified Information Elements. A vendor
   specified template MAY exclusively contain IETF defined Field Types.
   A vendor specified template MAY contain Vendor Specified Information
   Elements from multiple vendors.

   The format of the Vendor Specified Template FlowSet is shown in
   Figure D.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       FlowSet ID = 2          |          Length               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID 1           |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 1           |         Field Length 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  1.1                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 2           |         Field Length 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type N           |         Field Length N        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  1.N                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID 2           |         Field Count           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 1           |         Field Length 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type 2           |         Field Length 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  2.2                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             ...               |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Field Type M           |         Field Length M        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Enterprise Number  2.M                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure D: Vendor Specified Template Flowset

   The definition of the fields in the Vendor Specified Template
   FlowSet is identical to those described IETF exclusive Template
   FlowSet Format Field Descriptions except:

      FlowSet ID
         FlowSet ID value of 2 is reserved for the Vendor Specified
         Template FlowSet



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      Enterprise Number
         IANA enterprise number [PEN] of the authority defining the
         field type in this template record.

 8.4 Data FlowSet Format

   The format of the Data FlowSet is as follows:

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

   Data FlowSet Field Descriptions

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

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

   Record N - Field Value M



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           The remainder of the Data FlowSet is a collection of Flow
           Data Record(s), each containing a set of field types and
           values. The Type and Length of the fields have been
           previously defined in the Template Record referenced by the
           FlowSet ID or Template ID.

   Padding
           The Exporting Process SHOULD insert some padding bytes so
           that the subsequent FlowSet starts at a 4-byte aligned
           boundary. It is important to note that the Length field
           includes the padding bits.

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

 9. Options

 9.1 Options Template FlowSet Format

   The Options Template Record (and its corresponding Options Data
   Record) is used to supply information about the Metering Process
   configuration or Metering Process specific data, rather than
   supplying information about IP Flows.
   For example, the Options Template FlowSet can report the sample rate
   of a specific interface, if sampling is supported, along with the
   sampling method used.

 9.1.1    IETF Exclusive Options Template FlowSet Format

   The IETF exclusive Options Template FlowSet Format MAY be used
   when the template contains only IETF defined options. This format
   is provided for backwards compatibility [NETFLOW9]. The format of
   the IETF exclusive Options Template FlowSet Format is shown in
   Figure E.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       FlowSet ID = 1          |          Length               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Template ID           |      Option Scope Length      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


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   |        Option Length          |       Scope 1 Field Type      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Scope 1 Field Length      |               ...             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Scope N Field Length      |      Option 1 Field Type      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Option 1 Field Length     |             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Option M Field Length     |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure E: IETF Exclusive Options Template FlowSet

   The IETF Exclusive Options Template FlowSet Field Definitions are
   as follows:

   FlowSet ID = 1
           A FlowSet ID value of 1 is reserved for the Options
           Template.

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

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

   Option Scope Length
           The length in bytes of any Scope fields definition contained
           in the Options Template Record (The use of "Scope" is
           described below).

   Option Length
           The length (in bytes) of any options field definitions
           contained in this Options Template Record.



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   Scope 1 Field Type
           The relevant portion of the Exporting Process/Metering
           Process to which the Options Template Record refers.
           Currently defined values are:
               1 System
               2 Interface
               3 Line Card
               4 Cache
               5 Template
           For example, the Metering Process can be implemented on a
           per-interface basis, so if the Options Template Record were
           reporting on how the Metering Process is configured, the
           Scope for the report would be 2 (interface). The associated
           interface ID would then be carried in the associated Options
           Data FlowSet. The Scope can be limited further by listing
           multiple scopes that all must match at the same time. Note
           that the Scope fields always precede the Option fields.

   Scope 1 Field Length
           The length (in bytes) of the Scope field, as it would appear
           in an Options Data Record.

   Option 1 Field Type
           A numeric value that represents the type of field that would
           appear in the Options Template Record. Refer to [IPFIX-
           INFO].

   Option 1 Field Length
           The length (in bytes) of the Option Field.

   Padding
           The Exporting Process SHOULD insert some padding bytes so
           that the subsequent FlowSet starts at a 4-byte aligned
           boundary. It is important to note that the Length field
           includes the padding bits.

 9.1.2    Vendor Specified Options Template FlowSet Format

   A vendor specified Options Template MUST be used when the template
   contains one or more vendor specified options. A vendor specified
   Options Template MAY exclusively contain IETF defined Field Types. A
   vendor specified template MAY contain Vendor Specified Information
   Elements from multiple vendors.


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   The format of the Vendor Specified Options Template FlowSet is shown
   in Figure E.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       FlowSet ID = 3          |          Length               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Template ID           |      Option Scope Length      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Option Length          |    Reserved must be zero      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Scope 1 Field Type       |     Scope 1 Field Length      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Scope N Field Type       |     Scope N Field Length      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Scope N Enterprise Number                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Option 1 Field Type       |    Option 1 Field Length      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Option 1 Enterprise Number                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Option N Field Type       |    Option N Field Length      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure E: Vendor Specified Option Template FlowSet

   The definition of the fields in the vendor specified Options
   Template FlowSet is identical to those described IETF Exclusive
   Options Template FlowSet Format Field Descriptions except:

      FlowSet ID = 3
         A FlowSet ID value of 3 is reserved for a VI Qualified
         Options Template.

      Scope N Enterprise Number
         IANA enterprise number [PEN] of the authority defining
         Scope N.


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      Option N Enterprise Number
         IANA enterprise number [PEN] of the authority defining the
         Option N field type.

 9.2 Options Data Record Format

   The Options Data Records are sent in Data FlowSets, on a regular
   basis, but not with every Flow Data Record. How frequently these
   Options Data Records are exported is configurable. See the Templates
   Management" section for more details.

   The format of the Data FlowSet containing Options Data Records
   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    FlowSet ID = Template ID   |          Length               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 1 - Scope 1 Value    |Record 1 - Option Field 1 Value|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Record 1 - Option Field 2 Value|             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 2 - Scope 1 Value    |Record 2 - Option Field 1 Value|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Record 2 - Option Field 2 Value|             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Record 3 - Scope 1 Value    |Record 3 - Option Field 1 Value|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Record 3 - Option Field 2 Value|             ...               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              ...              |            Padding            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Options Data Records of the Data FlowSet Field Descriptions

   FlowSet ID = Template ID
           A FlowSet ID precedes each group of Options Data Records
           within a Data FlowSet. The FlowSet ID maps to a previously
           generated Template ID corresponding to this Options Template
           Record. The Collecting Process MUST use the FlowSet ID to



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           map the appropriate type and length to any field values that
           follow.

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

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

   Padding
           The Exporting Process SHOULD insert some padding bytes so
           that the subsequent FlowSet starts at a 4-byte aligned
           boundary. It is important to note that the Length field
           includes the padding bits.

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

 9.3 Specific IPFIX Options Templates

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

 The ipfixOption [IPFIX-INFO], always included in these specific
 Options Templates, defines the type of information sent in the Option
 Template / Option Template Record pair. For example, if the
 ipfixOption [IPFIX-INFO] value is METER_STATS, then the Option
 Template will specify information about the Metering Process
 statistics. The ipfixOption [IPFIX-INFO] MUST always be the first Data
 Type in the Option Template so that the Collector could quickly
 determine whether or not a specific Option Template is described. And
 if the ipfixOption [IPFIX-INFO] is present, which specific Option
 Template type it defines.



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 The minimum set of Data Types is always specified in these Specific
 IPFIX Options Templates. Nevertheless, extra Data Types MAY be used in
 these specific Options Templates.


 9.3.1   The Metering Process Statistics Option Template

 The Metering Process Statistics Option Template defines the Metering
 Process Statistics with the export of the following Data Types [IPFIX-
 INFO]:
     ipfixOption             The value MUST be METER_STATS
     observationDomain       Source ID
     lostFlows               flows not exported due to resource
                             starvation(**)
     lostFlowsPacket         Packets in the lost flows (**)
     lostFlowsBytes          Bytes in the lost flows (**)
     droppedPacketCount      Packets dropped by Metering Process
                            at the Observation Point
     droppedByteCount        Bytes dropped by Metering Process at the
                             Observation Domain
     time;                   When this record was generated

The minimum set of Data Type in the Metering Process Statistics Option
Template is: ipfixOption, observationDomain, lostFlows, time

 10. Export Packet UNIX Secs Computation and Flow Record Times

 10.1 Microsecond Precision

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

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

      struct flow{


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         uint32  tv_sec;
         uint32  tv_usec;
         uint32  numbytes;
         ...  // other information elements...
      };

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

      writeflows() {

         if (lastflowindex < 0) return;

         // simply take the second field from the first available flow
         // and make this the base time for this collection of flows.
         uint32  base_sec = flowtable[0].tv_sec;

         writeheaderToSocket(base_sec); // put 32-bit second value in header

         for (int i=0; i<=lastflowindex; i++){

            int32 offset = (flowtable[i].tv_sec - base_sec) * 1000000 +
   flowtable[i].tv_usec;
            writeint32ToSocket(offset);  // put the 32-bit time offset in the
   record.

            // write other information elements...
         }
      }

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

 10.2 Millisecond Precision

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

   The only difference will be that the Flow start and the Flow end
   SHOULD now be represented respectively by the flowStartMsec [IPFIX-
   INFO] and flowEndMsec [IPFIX-INFO]. As a consequence of the


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   millisecond precision, the absolute duration of all Flow Records is
   now of about 49 days. The Export Header UNIX Secs base time SHOULD
   be calculated with the algorithm described in the Section 9.1
   "Microsecond Precision". In order to reduce the load on the
   Exporter, the Export Header UNIX Secs MAY be the time in seconds
   since 0000 UTC 1970 at which the Export Packet leaves the Exporter
   and not the calculated optimum value anymore as described in section
   9.1 "Microsecond Precision".

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

 10.3 Nanosecond Precision

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

 10.4 Multiple Precisions

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

 11. Linkage with the Information Model

   The information model associates each IPFIX Data Type with a well
   defined type, such as hexBinary, long, unsignedInt, etc.

   This document defines how fields of a given type are encoded.

 11.1 Boolean



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   A boolean field shall be encoded in a single byte with the value of
   0 indicating false and any other value indicating true.

 11.2 Byte

   A byte value shall be encoded as a single byte representing a value
   between -128 and 127. The value is represented in two's complement
   notation.

 11.3 UnsignedByte

   An unsigned byte value shall be encoded as a single byte
   representing a value between 0 and 255.

 11.4 Short

   A short is a 16-bit datum that encodes an integer in the range [-
   32768,32767].  The short is represented in two's complement
   notation.  The most and least significant bytes are 0 and 1,
   respectively


   EDITOR NOTE: this section 11 must be completed with types used in
   [IPFIX-INFO], taking the descriptions from XDR RFC1832, sections 3.x

 11.5 Reduced Size Encoding of Integral Types

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

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




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   an access router.

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

   Reduced sizing MAY only be applied to the following integral types:
   short, unsignedShort, int, unsignedInt, long, unsignedLong. In each
   case the downcasting must be to a smaller integral type which MUST
   have the same signed vs. unsigned properties.

   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.

 12. Variable Length Data Type

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

   In the Template FlowSet 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
   itself.

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

   If the length of the Information Element is less than 255 bytes, the
   length is carried in the first byte of the Information Element. This
   is shown on Figure A.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Length (< 255)|          Information element                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |



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

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

   If the length of the Information Element is greater or equal than
   256 bytes, the first byte of the Information Element is 255, and the
   length is carried in the second and third bytes of the Information
   Element. This is shown in Figure B.

       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 (256 to 65535)       |   IE     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure B: Variable Length Information Element
               (length 256 to 65535) bytes

 13. Template Management

   Flow Data records that correspond to a Template Record MAY appear in
   the same and/or subsequent IPFIX Messages. The Template Record is
   not necessarily carried in every IPFIX Message. As such, the
   Collecting Process MUST store the Template Record to interpret the
   corresponding Flow Data Records that are received in subsequent data
   messages.

   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.

   The Template IDs must remain constant for the life of the Metering
   Process and the Exporting Process. If the Exporting Process or the
   Metering Process restarts for any reason, all information about
   Templates will be lost and new Template IDs will be created.
   Template IDs are thus not guaranteed to be consistent across an
   Exporting Process or Metering Process restart.

   A newly created Template record is assigned an unused Template ID
   from the Exporter. If the template configuration is changed, the


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   current Template ID is abandoned and SHOULD NOT be reused until the
   Metering Process. If a Collecting Process should receive a new
   definition for an already existing Template ID, it MUST discard the
   previous template definition and use the new one.

   If a configured Template Record on the Exporting Process is deleted,
   and re-configured with exactly the same parameters, the same
   Template ID COULD be reused.

   The Exporting Process sends the Template FlowSet and Options
   Template FlowSet under the following conditions:

    1. After a Metering Process restarts, the Exporting Process MUST
       NOT send any Data FlowSet without sending the corresponding
       Template FlowSet and the required Options Template FlowSet in a
       previous message or including it in the same IPFIX Message. It
       MAY transmit the Template FlowSet and Options Template FlowSet,
       without any Data FlowSets, in advance to help ensure that the
       Collector will have the correct Template Record before receiving
       the first Flow or Options Data Record.

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

    3. On a regular basis, the Exporting Process MUST send all the
       Template Records and Options Template Records to refresh the
       Collecting Process. Template IDs have a limited lifetime at the
       Collecting Process and MUST be periodically refreshed.
       Two approaches are taken to make sure that Templates get
       refreshed at the Collecting Process:
          * Every N number of IPFIX Messages.
          * On a time basis, so every N number of minutes.
       Both options MUST be configurable by the user on the Exporting
       Porcess.
       When one of these expiry conditions is met, the Exporting
       Process MUST send the Template FlowSet and Options Template.

 14. The Collecting Process's Side



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   The Collecting Process receives Template Records from the Exporting
   Process, normally before receiving Flow Data Records (or Options
   Data Records). The Flow Data Records (or Options Data Records) can
   then be decoded and stored locally on the devices. If the Template
   Records have not been received at the time Flow Data Records (or
   Options Data Records) are received, the Collecting Process SHOULD
   store the Flow Data Records (or Options Data Records) and decode
   them after the Template Records are received. A Collecting Process
   device MUST NOT assume that the Data FlowSet and the associated
   Template FlowSet (or Options Template FlowSet) are exported in the
   same IPFIX Message.

   The Collecting Process MUST NOT assume that one and only one
   Template FlowSet is present in an IPFIX Message.

   The life of a template at the Collecting Process is limited to a
   fixed refresh timeout. Templates not refreshed from the Exporting
   Process within the timeout are expired at the Collecting Process.
   The Collecting Process MUST NOT attempt to decode the Flow or
   Options Data Records with an expired Template. At any given time the
   Collecting Process SHOULD maintain the following for all the current
   Template Records and Options Template Records: <Exporting Process,
   Observation Domain, Template ID, Template Definition, Last Received>
   Note that the Observation Domain is identified by the Source ID
   field from the IPFIX Message.

   Template IDs are unique per Exporting Process and per Observation
   Domain.

   If the Collecting Process receives a new Template Record (for
   example, in the case of an Exporter restart) it MUST immediately
   override the existing Template Record.

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

   The Collector MUST accept padding in the Data FlowSet and Options
   Template FlowSet, which means for the Flow Data Records, the Options
   Data Records and the Template Records.


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   Refer to the terminology summary table in Section 3.1.

   The IPFIX protocol has a sequence number field in the Export Header
   which increases with each message. A Collector may detect out of
   sequence, dropped, or duplicate messages by tracking the sequence
   number.  A collector SHOULD provide a logging mechanism for tracking
   out of sequence messages.  Such out of sequence messages may be due
   to 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, Exporter
   resource exhaustion where it can not transmit messages at their
   creation rate, out of order packet reception, duplicate packet
   reception, an Exporting Process reset, or an attacker injecting
   false messages.

 15. Security Considerations

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

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

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

   The IPFIX protocol runs over IP and hence the messages sent to the
   collector by the exporter may be secured using IPsec. However this
   does not address all of the security issues in an IPsec deployment.

 15.1 IPsec Profile

   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].





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 15.1.1  Selectors

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

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

 15.1.2  Mode

   IPsec MUST be run in transport mode.

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

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

   The AH MUST be supported by an IPFIX implementation of IPsec.


 15.1.3  Key Management

   In many networks, manual key management will be sufficient, and
   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 the
   IKE key management system SHOULD be used.

 15.1.4  Security Policy

   Connections should be accepted only from the designated peer.

 15.1.5  Authentication

   Given the number of IPFIX capable Exporters are likely to be deployed
   by a 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.






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 15.1.6  Availability

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

 15.2 Network Architecture

   Ideally messages from the IPFIX Exporter to the IPFIX Collector
   should travel over a dedicated network such as a dedicated point to
   point link. In all cases, useful protection is gained by allocating
   Exporter and Collector IP addresses from ranges that are excluded
   from use for user traffic. By sending the IPFIX messages over a
   dedicated network, message 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.

   The use of a dedicated network also prevents the IPFIX messages from
   being inspected by an attacker.

 15.3 When IPsec is not an option

   When IPsec is not an option, perhaps due to performance issues, but
   some level of protection against an insertion attack is required, it
   is recommended that a 64 bit cookie [L2TPv3] be included as a
   mandatory element within all messages.

   Without IPsec the IPFIX Collector has no means to authenticate an
   exporter other than the Exporters Source IP address. 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, this leaves the Collector open to reception of
   invalid flows. The use proxies using an open collector is therefore
   to be deprecated.

 15.4 Transport Issues

   Some IPFIX security issues are dependent on the transport. For
   example with UDP unsolicited messages may be received and not
   detected, with a modern implementation of TCP with good ISN
   randomization [XXX-REFERENCE] or SCTP these types of attacks are much
   more difficult without an attacker with access to snoop the packet
   flow [XXX-SCTP-BLIND-SPOOFING-REFERENCE]. Randomization of the IPFIX
   sequence number might mitigate the in case of UDP problem. However in
   all these cases, the sequence number space is relatively small giving


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   limited protection.

   An attacker may take advantage of the pathology of the transport
   protocol or its common implementations to mount and attack on IPFIX.
   This might be either as an assault on IPFIX in its own right or
   intended to blind IPFIX to prevent the recording of network forensics
   as part of another attack.

   Under conditions where the attacker saturated IPFIX, for example by
   initiating the generating enormous numbers of short lived flows, the
   behavior of the IPFIX transport would determine the amount of
   evidence that was recorded.

   If the transport protocol were UDP, then under network overload
   conditions IPFIX would reduce to some sort of sampling. This means
   that the attacked could never be quite sure that IPFIX was blinded,
   and that they may hence be leaving forensics.

   If the transport were TCP, then the flow to the collector would back
   off due to congestion discard and eventually stall blinding the IPFIX
   system. An attack could then proceed without further observation. The
   extent and duration of the blindness would depend on the detail of
   the TCP implementation.

   SCTP-PR will have a different pathology under such a saturation
   attack. Stale data at the head of the queue will get flushed giving
   some visibility of the attack.

   Whilst the use of a congestion aware transport protocol is highly
   desirable to protect the network from overload by excessive IPFIX
   traffic, this is exactly wrong behavior when IPFIX is being to
   diagnose a DoS attack, or an attack proceeding under cover of a DoS
   attack. Under these circumstance you want the IPFIX transport needs
   to be congestion neutral (as is UDP), or congestion aggressive.

 15.5 Logging an IPFIX Attack

   The IPFIX protocol has a sequence number field in the Export Header
   which increases with each message. A Collector may detect out of
   sequence, dropped, or duplicate messages by tracking the sequence
   number. A Collector SHOULD provide a logging mechanism for tracking
   out of sequence messages. Such out of sequence messages may be due
   to 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, Exporter resource
   exhaustion where it can not transmit messages at their creation
   rate, out of order packet reception, duplicate packet reception, an
   Exporting Process reset, or an attacker injecting false messages.



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   Note that an attacker may be able to exploit the behavior of the
   Collector when it receives an out of sequence message. For example a
   Collector that simply reset the expected sequence number upon
   receipt of a later message would easily be temporarily blinded by
   deliberately injecting messages with a much larger sequence number.

 16. IANA Considerations

   IANA will need to set up a registry of Flowset IDs, field types,
   scope and option codepoints.

   In compiling the registry of field types IANA must set asside a
   range value for vendor use. It is proposed that the range <0..32767>
   be administered by IANA for IETF defined IEs, and that the range
   <32768..65535> be allocated for private use by vendors.

   Similarly the scope and option codepoints need to be split between
   IANA administered and private ranges.

 17. Examples

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

   IPFIX Message:
   +--------+---------------------------------------------. . .
   |        | +--------------+ +-----------------------+
   |Message | | Template     | | Data                  |
   | Header | | FlowSet      | | FlowSet               |   . . .
   |        | | (1 Template) | | (3 Flow Data Records) |
   |        | +--------------+ +-----------------------+
   +--------+---------------------------------------------. . .

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




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 17.1 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 = 0x0009          |         Length = 152          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           UNIX Secs                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Sequence Number                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Source ID                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 17.2 Template FlowSet Example

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

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



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

 17.3 Data FlowSet Example

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

   Src IP addr. | Dst IP addr. | Next Hop addr. | Packet | Bytes
                |              |                | Number | Number
   ---------------------------------------------------------------
   198.168.1.12 | 10.5.12.254  | 192.168.1.1    | 5009   | 5344385
   192.168.1.27 | 10.5.12.23   | 192.168.1.1    | 748    | 388934
   192.168.1.56 | 10.5.12.65   | 192.168.1.1    | 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       FlowSet ID = 256        |          Length = 64          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          198.168.1.12                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          10.5.12.254                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.1                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             5009                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                            5344385                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.27                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           10.5.12.23                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.1                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              748                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             388934                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          192.168.1.56                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           10.5.12.65                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           192.168.1.1                         |


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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               5                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              6534                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Note that padding was not necessary in this example.

 17.4 Options Template FlowSet Example

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

   The format of the Options Template FlowSet is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       FlowSet ID = 1          |          Length = 24          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Template ID 257         |    Option Scope Length = 4    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Option Length = 8       |  Scope 1 Field Type = 0x0003  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Scope 1 Field Length = 2    |   TOTAL_EXP_PKTS_SENT = 41    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |     TOTAL_FLOWS_EXP = 42      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Field Length = 4        |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 17.5 Data FlowSet with Options Data Records Example

   In this example, we report the following two records:

   Line Card ID | IPFIX Message| Export Flow
   ------------------------------------------
   Line Card 1  | 345           | 10201
   Line Card 2  | 690           | 20402

    0                   1                   2                   3



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                   IPFIX Protocol Specifications          January 2004


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    FlowSet ID = 257           |         Length = 14           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             1                 |             345               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           10201               |              2                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             2                 |             690               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           20402               |           Padding             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 18. References


 18.1 Normative References

   [IPFIX-ARCH] Sadasivan, G, Brownlee, N. "Architecture Model for IP
   Flow Information Export" draft-ietf-ipfix-arch-01.txt", June 2003

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

   [IPFIX-AS] Claise, B, Fullmer, M, Calato, P, Penno, R, "IPFIX
   Protocol Specifications", draft-ietf-ipfix-protocol-00.txt, June
   2003

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

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

   [PR-SCTP] Stewart, R, Ramalho, M, Xie, Q, Tuexen, M, Conrad, P.
   "SCTP Partial Reliability Extension", draft-ietf-tswg-prsctp-02.txt

   [NETFLOW9] Claise, B, et al "Cisco Systems NetFlow Services Export
   Version 9", draft-claise-netflow-9-06.txt, October 2003

 18.2 Informative References





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                   IPFIX Protocol Specifications          January 2004


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

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

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

   [NETFLOW9] Claise, B, et al "Cisco Systems NetFlow Services Export
   Version 9", draft-claise-netflow-9-06.txt, October 2003

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

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

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

   [XXX-REFERENCE]

   [XXX-SCTP-BLIND-SPOOFING-REFERENCE]

 19. Acknowledgments

   To be completed.

 Authors Addresses

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




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                   IPFIX Protocol Specifications          January 2004


   Mark Fullmer
   OARnet
   2455 North Star Rd.
   Columbus, Ohio 43221
   Phone: +1 (614) 728-8100
   Email: maf@eng.oar.net

   Reinaldo Penno
   Nortel Networks
   2305 Mission College Blvd
   Santa Clara, CA 95054
   Phone: +1 408.565.3023
   Email: rpenno@nortelnetworks.com

   Paul Calato
   Riverstone Networks, Inc.
   5200 Great America Parkway
   Santa Clara, CA 95054  USA
   Phone:  +1 (603) 557-6913
   Email: calato@riverstonenet.com

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

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









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