IPFIX working group                                                  
   Internet Draft                               EDITOR:      B. Claise 
   draft-ietf-ipfix-protocol-07.txt                       Cisco Systems 
   Expires: June 2005                                     December 2004 
                                                                        
                                                                        
    
    
    
                       IPFIX Protocol Specification  
 
                                      
    
 Status of this Memo 
  
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   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026.  
    
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 Abstract 
  
   This document specifies the IPFIX protocol that provides network 
   operators with access to IP flow information.  In order to export 
   IP flow information to the IPFIX collecting process, a common method 
   of representing the flow data and a standard means of communicating 
   them from an exporter to a collector is required.  This document 
   describes how the IPFIX flow record data, options record data and 

 
 
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   templates are carried over a congestion-aware transport protocol 
   from an IPFIX exporting process to an IPFIX collecting process. 
    
 Conventions used in this document 
  
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 
   document are to be interpreted as described in RFC 2119. 
    
 Table of Contents 
  
     1. Points of Discussion.........................................4 
     2. Introduction.................................................5 
      2.1 IPFIX Documents Overview...................................6 
     3. Terminology..................................................6 
      3.1 Terminology Summary Table.................................11 
     4. Criteria for Flow Expiration and Export.....................12 
      4.1 Flow Expiration...........................................12 
      4.2 Flow Export...............................................12 
     5. Message Format..............................................13 
     6. IPFIX Message Format........................................15 
      6.1 Header Format.............................................15 
      6.2 Field Type Format.........................................16 
      6.3 Template Set Format.......................................17 
      6.4 Data Set Format...........................................19 
      6.5 Options Template Set......................................21 
     6.5.1   Scope..................................................21 
     6.5.2   Options Template Set Format............................22 
     6.5.3   Options Data Record Format.............................24 
     7. Specific Reporting Requirements.............................26 
      7.1 The Metering Process Statistics Option Template...........26 
      7.2 The Metering Process Reliability Statistics Option Template27 
      7.3 The Exporting Process Reliability Statistics Option Template28 
      7.4 The Flow Keys Option Template.............................28 
     8. "Export Time" Computation and Flow Record Time..............29 
      8.1 Microsecond Precision.....................................29 
      8.2 Millisecond Precision.....................................30 
      8.3 Nanosecond Precision......................................31 
      8.4 Multiple Precisions.......................................31 
     9. Linkage with the Information Model..........................31 
      9.1 Reduced Size Encoding of Integer Types....................31 
     10. Variable Length Information Element........................32 
     11. Template Management........................................33 
     12. The Collecting Process's Side..............................36 
     13. Transport Protocol.........................................38 
      13.1 Transport Compliance and Transport Usage.................38 
      13.2 TCP......................................................39 
     13.2.1  Congestion Avoidance...................................39 
 
 
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     13.2.2  Reliability............................................39 
     13.2.3  MTU....................................................39 
     13.2.4  Exporting Process......................................39 
     13.2.4.1 Connection Establishment..............................39 
     13.2.4.2 Connection Release....................................40 
     13.2.4.3 IPFIX Message Encoding................................40 
     13.2.5  Template Management....................................40 
     13.2.6  Fail-over..............................................41 
      13.3 SCTP.....................................................41 
     13.3.1  Congestion Avoidance...................................41 
     13.3.2  Reliability............................................41 
     13.3.3  MTU....................................................42 
     13.3.4  Exporting Process......................................42 
     13.3.4.1 Association Establishment.............................42 
     13.3.4.2 Association Shutdown..................................42 
     13.3.4.3 Source ID.............................................43 
     13.3.4.4 Stream................................................43 
     13.3.4.5 Template Management...................................44 
     13.3.5  Collecting Process.....................................44 
     13.3.6  Failover...............................................44 
      13.4 UDP......................................................44 
     13.4.1  Congestion Avoidance...................................44 
     13.4.2  Reliability............................................44 
     13.4.3  MTU....................................................45 
     13.4.4  Port Numbers...........................................45 
     13.4.5  Exporting Process......................................45 
     13.4.6  Template Management....................................45 
     13.4.7  Collecting Process.....................................46 
     13.4.8  Failover...............................................47 
     14. Security Considerations....................................47 
      14.1 IPsec Usage..............................................47 
     14.1.1  Selectors..............................................48 
     14.1.2  Mode...................................................48 
     14.1.3  Key Management.........................................48 
     14.1.4  Security Policy........................................48 
     14.1.5  Authentication.........................................48 
     14.1.6  Availability...........................................49 
      14.2 TLS Usage................................................49 
      14.3 Protection against DoS attacks...........................49 
      14.4 When IPsec or TLS is not an option.......................50 
      14.5 Logging an IPFIX Attack..................................50 
     15. IANA Considerations........................................51 
      15.1 Numbers used in the Protocol.............................51 
      15.2 Numbers used in the Information Model....................51 
     16. Examples...................................................52 
      16.1 Message Header Example...................................52 
      16.2 Template Set Examples....................................53 
     16.2.1  Template Set using IETF specified Information Elements53 

 
 
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     16.2.2  Template Set using Enterprise Specific Information 
     Elements 53 
      16.3 Data Set Example.........................................54 
      16.4 Options Template Set Examples............................55 
     16.4.1  Options Template Set using IETF specified Information 
     Elements 55 
     16.4.2  Options Template Set using Enterprise Specific 
     Information Elements...........................................56 
     16.4.3  Options Template Set using an Enterprise Specific scope57 
      16.5 Data Set with Options Data Records Example...............57 
     17. References.................................................58 
      17.1 Normative References.....................................58 
      17.2 Informative References...................................59 
     18. Acknowledgments............................................60 
  
 1.     Points of Discussion 
    
   This section covers the open issues, still to be resolved/updated in 
   this draft.  Note that the issues starting with PROTO-31 have been 
   added to this draft version.  
    
   PROTO-23: Finalize the time details. The time-related Information 
   Elements are not defined in [IPFIX-INFO]. We agree that the 
   definition of timer semantics should be moved to the info model 
   document (see the http://ipfix.doit.wisc.edu/archive/2588.html email 
   thread). Now we need: 
   - to insert some new text in the section 9 of this document 
   - to insert the timing Information Element in [IFPIX-INFO] 
   Note: see http://ipfix.doit.wisc.edu/archive/2580.html for a way to 
   improve the timing-related Information Elements. 
 
   PROTO-30: review RFC 3917, to see if we miss any requirements 
 
   PROTO-34: Need a security expert to review the security section: 
          - [TBD] in the security section 
          - [EDITOR NOTE: the security section may need be adapted to 
          the revised transport section], [XXX-REFERENCE] 
          - [XXX-SCTP-BLIND-SPOOFING-REFERENCE] not defined 
          - TCP Security 
          1. Handshake: should we introduce a handshake sequence at the 
          start of the connection? A simple ASCII-based handshake could 
          be used to request TLS.  
          2. It would make sense to add TLS support even in the absence 
          of a handshake. It would be the responsibility of the 

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

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

   PROTO-47: Some ææEDITORÆS NOTEÆÆ in the draft. 

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

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

 
 
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 2.1      IPFIX Documents Overview 
    
   The IPFIX protocol provides network administrators with access to IP 
   flow information.  The architecture for the export of measured IP 
   flow information out of an IPFIX exporting process to a collecting 
   process is defined in [IPFIX-ARCH], per the requirements defined in 
   [IPFIX-REQ].  This document specifies how IPFIX flow record data, 
   options record data, and templates are carried via a congestion-
   aware transport protocol from IPFIX exporting process to IPFIX 
   collecting process.  IPFIX has a formal description of IPFIX 
   information elements (fields), their name, type and additional 
   semantic information, as specified in [IPFIX-INFO].  Finally [IPFIX-
   AS] describes what type of applications can use the IPFIX protocol 
   and how they can use the information provided.  It furthermore shows 
   how the IPFIX framework relates to other architectures and 
   frameworks.  
    
 3.    Terminology 
 
   The definitions of the basic terms like IP Traffic Flow, Exporting 
   Process, Collecting Process, Observation Points, etc. are 
   semantically identical with that found in the IPFIX requirements 
   document [IPFIX-REQ].  Some of the terms have been expanded for more 
   clarity when defining the protocol.  Additional terms required for 
   the protocol has also been defined.  Definitions in this document 
   and in [IPFIX-ARCH] are equivalent, except that definitions which 
   are only relevant to the IPFIX protocol only appear here.  Should 
   there be any apparent discrepancy in definitions between these two 
   documents, the definitions defined in this document take precedence. 
    
   The terminology summary table in Section 3.1 gives a quick overview 
   of the relationships between some of the different terms defined. 
  
 Observation Point 
 
   An Observation Point is a location in the network where IP packets 
   can be observed.  Examples include: a line to which a probe is 
   attached, a shared medium, such as an Ethernet-based LAN, a single 
   port of a router, or a set of interfaces (physical or logical) of a 
   router. 
    
   Note that one Observation Point may be a superset of several 
   other Observation Points.  For example, one Observation Point can be 

 
 
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   an entire line card.  This would be the superset of the 
   individual Observation Points at the line card's interfaces.  
 
 Observation Domain 
    
   An Observation Domain is the largest set of Observation Points for 
   which Flow information can be aggregated by a Metering Process.  
   Each Observation Domain presents itself using a unique ID to the 
   Collecting Process to identify the IPFIX Messages it generates.  For 
   example, a router line card may be an observation domain if it is 
   composed of several interfaces: each of which is  an Observation 
   Point.  Every Observation Point is associated with an Observation 
   Domain. 
 
 IP Traffic Flow or Flow 
 
   There are several definitions of the term 'flow' being used by the 
   Internet community.  Within the context of IPFIX we use the 
   following definition: 
    
   A Flow is defined as a set of IP packets passing an Observation 
   Point in the network during a certain time interval.  All packets 
   belonging to a particular Flow have a set of common properties.  
   Each property is defined as the result of applying a function to the 
   values of: 
    
      1. one or more packet header field (e.g. destination IP address),    
      transport header field (e.g. destination port number), or  
      application header field (e.g. RTP header fields [RFC1889]) 
    
      2. one or more characteristics of the packet itself (e.g. number  
      of MPLS labels, etc...) 
    
      3. one or more of fields derived from packet treatment (e.g. next  
      hop IP address, the output interface, etc...) 
    
   A packet is defined to belong to a Flow if it completely satisfies 
   all the defined properties of the Flow. 
    
   This definition covers the range from a Flow containing all packets 
   observed at a network interface to a Flow consisting of just a 
   single packet between two applications.  It includes packets 
   selected by a sampling mechanism. 
 
 
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 Flow Key 
  
   Each of the fields which 
    
   1.  Belong to the packet header (e.g. destination IP address) 
    
   2.  Are a property of the packet itself (e.g. packet length) 
    
   3.  Are derived from packet treatment (e.g. AS number) 
    
   and which are used to define a Flow are termed Flow Keys. 
    
 Flow Record 
 
   A Flow Record contains information about a specific Flow that was 
   observed at an Observation Point.  A Flow Record contains measured 
   properties of the Flow (e.g. the total number of bytes of all 
   packets of the Flow) and usually characteristic properties of the 
   Flow (e.g. source IP address).  
    
 Metering Process 
 
   The Metering Process generates Flow Records.  Input to the process 
   are packet headers observed at an Observation Point and packet 
   treatment at the Observation Point (for example the selected output 
   interface). 
    
   The Metering Process consists of a set of functions that includes 
   packet header capturing, timestamping, sampling, classifying, and 
   maintaining Flow Records. 
    
   The maintenance of Flow Records may include creating new records, 
   updating existing ones, computing Flow statistics, deriving further 
   Flow properties, detecting Flow expiration, passing Flow Records to 
   the Exporting Process, and deleting Flow Records. 
    
 Exporting Process 
 
   The Exporting Process sends Flow Records to one or more Collecting 
   Processes.  The Flow Records are generated by one or more Metering 
   Processes. 
    
 
 
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 IPFIX Device 
    
   An IPFIX Device hosts at least one Observation Point, a Metering 
   Process and an Exporting Process.  Typically, corresponding 
   Observation Point(s), Metering Process(es) and Exporting Process(es) 
   are co-located at such a device, for example at a router. 
    
 Exporter 
 
   A device which hosts one or more Exporting Processes is termed an 
   Exporter.  
    
 Collecting Process 
 
   A Collecting Process receives Flow Records from one or more 
   Exporting Processes.  The Collecting Process might process or store 
   received Flow Records, but such actions are out of scope for this 
   document. 
    
 Collector 
 
   A device which hosts one or more Collecting Processes is termed a 
   Collector. 
    
 Template 
 
   Template is an ordered sequence of pairs (<type,length>), used to 
   completely identify the structure and semantics of a particular 
   information that needs to be communicated from the IPFIX Device to 
   the Collector.  Each Template is uniquely identifiable by means of a 
   Template ID. 
    
 IPFIX Message 
 
   An IPFIX Message is a message originating at the Exporting Process 
   that carries the IPFIX records of this Exporting Process and whose 
   destination is the Collecting Process.  An IPFIX Message is 
   encapsulated within a transport layer. 
    
 Message Header 
 



 
 
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   The Message Header is the first part of an IPFIX Message, which 
   provides basic information about the message such as the IPFIX 
   version, length of the message, message sequence number, etc. 
    
 Template Record 
 
   A Template Record defines the structure and interpretation of fields 
   in a Flow Data Record. 
    
 Flow Data Record 
 
   A Flow Data Record is a data record that contains values of the Flow 
   parameters corresponding to a Template Record.  
    
 Options Template Record 
 
   An Options Template Record defines the structure and interpretation 
   of fields in an Options Data Record, including defining how to scope 
   the applicability of the Options Data Record. 
    
 Options Data Record 
   The Options Data Record is a data record that contains values and 
   scope information of the Flow measurement parameters, corresponding 
   to an Options Template Record. 
    
 Set 
 
   Set is a generic term for a collection of records that have a 
   similar structure.  In an IPFIX Message, one or more Sets follow the 
   Message Header. 
    
   There are three different types of Sets: Template Set, Options 
   Template Set, and Data Set.  
     
 Template Set 
 
   A Template Set is a collection of one or more Template Records that 
   have been grouped together in an IPFIX Message.  
     
 Options Template Set 
 


 
 
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   An Options Template Set is a collection of one or more Options 
   Template Records that have been grouped together in an IPFIX 
   Message. 
    
 Data Set 
 
   A Data Set is one or more records, of the same type, that are 
   grouped together in an IPFIX Message.  Each record is either a Flow 
   Data Record or an Options Data Record previously defined by a 
   Template Record or an Options Template Record. 
    
 Information Element 
    
   An Information Element is a protocol and encoding independent 
   description of an attribute which may appear in an IPFIX Flow 
   Record.  The IPFIX information model [IPFIX-INFO] defines the base 
   set of Information Elements for IPFIX.  The type associated with an 
   Information Element indicates constraints on what it may contain and 
   also determine the valid encoding mechanisms for use in IPFIX. 
 
 3.1      Terminology Summary Table 
 
    +------------------+---------------------------------------------+ 
    |                  |                    Contents                 | 
    |                  +--------------------+------------------------+ 
    |       Set        | Template  Record   |      data record       | 
    +------------------+--------------------+------------------------+ 
    |                  |                    |  Flow Data Record(s)   | 
    |   Data Set       |          /         |          or            | 
    |                  |                    | Options Data Record(s) | 
    +------------------+--------------------+------------------------+ 
    |   Template Set   | Template Record(s) |           /            | 
    +------------------+--------------------+------------------------+ 
    | Options Template | Options Template   |           /            | 
    |       Set        | Record(s)          |                        | 
    +------------------+--------------------+------------------------+ 
 
      Figure A: Terminology Summary Table 
    
   A Data Set is composed of an Options Data Record(s) or Flow Data 
   Record(s).  No Template Record is included.  A Template Record 
   defines the Flow Data Record, and an Options Template Record defines 
   the Options Data Record.  
 
 
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   A Template Set is composed of Template Record(s).  No Flow or 
   Options Data Record is included. 
     
   An Options Template Set is composed of Options Template Record(s).  
   No Flow or Options Data Record is included.  
 
 4.     Criteria for Flow Expiration and Export  
    
 4.1      Flow Expiration 
     
   A Flow is considered as expired under the following conditions:  
    
   1. If the Metering Process can deduce the end of a Flow, that 
   Flow Record should be exported when the end of the Flow is 
   detected.  For example, a Flow generated by TCP [TCP] traffic where 
   the FIN or RST bits indicate the end of the Flow Record.  
    
   2. If no packets belonging to the Flow have been observed for a 
   certain period of time.  This time period should be configurable at 
   the Metering Process, with a minimum value of 0 seconds for 
   immediate expiration.  Note that a zero timeout would report a Flow 
   as a sequence of single-packet Flows. 
    
   3. If the IPFIX Device experiences resource constraints, a Flow 
   Record may be prematurely expired (e.g. lack of memory to store Flow 
   Records). 
    
   4. For long-running Flows, the Metering Process should expire the  
   Flow Record on a regular basis or based on some expiration policy.  
   This periodicity or expiration policy should be configurable at the 
   Metering Process. When the Record of a long-running Flow is expired, 
   that Flow Record may still be maintained by the Metering Process so 
   that, for further observed packets of the same Flow Record, the 
   Metering Process does not need to create a new Flow Record. 
     
 4.2      Flow Export 
    
   The Exporting Process decides when and whether to export an expired 
   Flow.  A Flow can be exported because it expired due to the reasons 
   mentioned in Flow Expiration section.  For example: the Exporting 
   Process exports a portion of the expired Flows every 'x' seconds.  
    

 
 
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   For long-lasting Flows, the Exporting Process should export the Flow 
   Records on a regular basis or based on some export policy.  This 
   periodicity or export policy should be configurable at the Metering 
   Process. 
    
 5.     Message Format  
    
   An IPFIX Message consists of a Message Header followed by one or 
   more Sets.  The Sets can be any of the possible three types: 
   Template, Data, or Options Template.   
    
   The format of the IPFIX Message is shown in Figure B. 
    
   +--------+-------------------------------------------+ 
   |        | +----------+ +---------+ +----------+     | 
   |Message | | Template | |  Data   | | Options  |     | 
   | Header | |   Set    | |   Set   | | Template | ... | 
   |        | |          | |         | |    Set   |     | 
   |        | +----------+ +---------+ +----------+     | 
   +--------+-------------------------------------------+ 
    
      Figure B: IPFIX Message format 
 
   A Set ID is used to distinguish the different types of Sets.  Set 
   IDs lower than 256 are reserved for special Sets, such as the 
   Template Set (ID 2) and the Options Template Set (ID 3).  The Data 
   Sets have a Set ID greater than 255.  The Set ID value of 0 and 1 
   are not used for historical reasons [NETFLOW9]. 
    
   The format of the Template, Data, and Options Template Sets will be 
   discussed later in this document.  The Exporter MUST code all binary 
   integers of the Message Header and the different Sets in network 
   byte order (also known as the big-endian byte ordering). 
    
   Following are some examples of IPFIX Messages: 
    
   1. An IPFIX Message consisting of interleaved Template, Data, and 
   Options Template Sets-A newly created Template is exported as soon 
   as possible.  So if there is already an IPFIX Message with a Data 
   Set that is being prepared for export, the Template and Option Sets 
   are also interleaved with this information, subject to availability 
   of space. 
    
 
 
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   +--------+--------------------------------------------------------+ 
   |        | +----------+ +---------+     +-----------+ +---------+ | 
   |Message | | Template | | Data    |     | Options   | | Data    | | 
   | Header | | Set      | | Set     | ... | Template  | | Set     | | 
   |        | |          | |         |     | Set       | |         | | 
   |        | +----------+ +---------+     +-----------+ +---------+ | 
   +--------+--------------------------------------------------------+  
    
      Figure C: IPFIX Message example 1 
    
   2. An IPFIX Message consisting entirely of Data Sets-After the 
   appropriate Template Records have been defined and transmitted to 
   the Collecting Process, the majority of IPFIX Messages consist 
   solely of Data Sets.   
    
   +--------+----------------------------------------------+ 
   |        | +---------+     +---------+      +---------+ | 
   |Message | | Data    | ... | Data    | ...  | Data    | | 
   | Header | | Set     | ... | Set     | ...  | Set     | | 
   |        | +---------+     +---------+      +---------+ | 
   +--------+----------------------------------------------+   
    
      Figure D: IPFIX Message example 2 
 
   3. An IPFIX Message consisting entirely of Template and Options 
   Template Sets-When UDP is used as the transport protocol, Templates 
   Sets and Option Template Sets MUST be sent periodically to help 
   ensure that the Collecting Process has the correct Template Records 
   and Options Template Records when the corresponding Flow Data 
   Records are received.   
    
   +--------+-------------------------------------------------+ 
   |        | +----------+     +----------+      +----------+ | 
   |Message | | Template |     | Template |      | Options  | | 
   | Header | | Set      | ... | Set      | ...  | Template | | 
   |        | |          |     |          |      | Set      | | 
   |        | +----------+     +----------+      +----------+ | 
   +--------+-------------------------------------------------+ 
    
      Figure E: IPFIX Message example 3 
    
    

 
 
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 6.     IPFIX Message Format 
    
 6.1      Header Format 
    
   The format of the IPFIX Message Header format is shown in Figure F. 
    
    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |       Version Number          |            Length             | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                           Export Time                         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                       Sequence Number                         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          Source ID                            | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
      Figure F: IPFIX Message Header format 
    
   Message Header Field Descriptions  
    
   Version 
           Version of Flow Record format exported in this message.  The 
           value of this field is 0x000a for the current version. 
            
   Length 
           Total Length is the length of the IPFIX Message, measured in 
           octets, including message Header and Set(s). 
             
   Export Time 
           Time in seconds since 0000 UTC 1970, at which the IPFIX 
           Message Header leaves the Exporter. 
            
   Sequence Number                                        
           Incremental sequence counter modulo 2exp32  of all IPFIX  
           Messages sent on this stream from the current Observation  
           Domain by the Exporting Process. This value SHOULD be used  
           by the Collecting Process to identify whether any IPFIX  
           Messages have been missed. 
            
   Source ID 


 
 
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           A 32-bit value that identifies the Exporter Process 
           Observation Domain.  Collecting Process SHOULD use the 
           combination of the source IP address and the Source ID field 
           to separate different export streams originating from the 
           same Exporting Process. 
            
 6.2      Field Type Format 
            
   Vendors need the ability to define proprietary Information Elements, 
   because, for example, they are delivering pre-standards product, or 
   the Information Element is in some way commercially sensitive.  This 
   section describes the Field Type format for both IETF specified 
   Information Elements [IPFIX-INFO] and Enterprise Specific 
   Information Elements, both the Template Set and the Option Template 
   Set.   
    
   The Field Ids used to identify Information Elements are represented 
   by the Field Type.  When the Enterprise Field Type bit is set to 0, 
   the corresponding Field Type will report an IETF specified 
   Information Elements.  When the Enterprise Field Type bit is set to 
   1, the corresponding Field Type will report an Enterprise Specific 
   Information Element.  An example of this is shown in section 16. 
    
    
   The Field Type format is shown in Figure G. 
     
        0                   1                   2                   3  
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |E|      Field Type             |        Field Length           |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |                      Enterprise Number                        |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      
          Figure G: Field Type format 
      
        Where: 
      
       E  
          Enterprise Field Type.  This is the first bit of the Field  
          Type. If this bit is zero, the Field Type identifies an IETF  
          specified Information Element, and the four octet Enterprise  
          Number field MUST NOT be present.  If this bit is one, the  
 
 
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          Field Type identifies an Enterprise Specific Information  
          Element, and the Enterprise Number filed MUST be present.   
      
      Field Type  
         A numeric value that represents the type of the field.  Refer    
         to [IPFIX-INFO].   
    
      Field Length  
         The length of the corresponding Field Type, in bytes.  Refer    
         to [IPFIX-INFO].   
    
      Enterprise Number  
         IANA enterprise number [PEN] of the authority defining the  
         Field Type in this Template Record. 
 
 6.3      Template Set Format 
    
   One of the essential elements in the IPFIX format is the Template 
   Set.  Templates greatly enhance the flexibility of the Flow Record 
   format because they allow the Collecting Process to process Flow 
   Records without necessarily knowing the interpretation of all the 
   data in the Flow Record.  A Template Set MAY exclusively contain 
   IETF defined Field Types.  A Template Set MAY contain Enterprise 
   Specific Information Elements from one or more vendors.   
    
   The format of the Template Set is shown in Figure H.   
    
       0                   1                   2                   3 
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |          Set ID = 2           |          Length               |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |      Template ID 256          |         Field Count 1         |   
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       Field Type 1.1          |        Field Length 1.1       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |                    Enterprise Number  1.1                     |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       Field Type 1.2          |        Field Length 1.2       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |             ...               |              ...              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       Field Type 1.N          |        Field Length 1.N       |  
 
 
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |                    Enterprise Number  1.N                     |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |      Template ID 257          |         Field Count 2         |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       Field Type 2.1          |        Field Length 2.1       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       Field Type 2.2          |        Field Length 2.2       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |                    Enterprise Number  2.2                     |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |             ...               |              ...              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       Field Type 2.M          |        Field Length 2.M       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |                    Enterprise Number  2.M                     |       
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |                          Padding (opt)                        |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
            Figure H: Template Set Format 
    
   Field Types 1.2 and 2.1 are defined by the IETF (bit 0 = 0) and  
   therefore do not need and Enterprise Number to identify them. 
    
   The Template Set Field Definitions are as follows: 
    
     Set ID 
           Set ID value of 2 is reserved for the Template Set. 
 
     Length 
           Total length of this Set.  Because an individual Template 
           Set MAY contain multiple Template Records, the Length value 
           MUST be used to determine the position of the next Set 
           record, which could be any type of Set.  Length is the sum 
           of the lengths of the Set ID, the Length itself, and all 
           Template Records within this Set. 
            
     Template ID 
           Each of the newly generated Template Records is given a 
           unique Template ID.  This uniqueness is local to the 
           Observation Domain that generated the Template ID.       

 
 
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           Template IDs 0-255 are reserved for Template Sets, Options 
           Sets, and other reserved Sets yet to be created.  Template 
           IDs of Data Sets are numbered from 256 to 65535. 
            
     Field Count 
           Number of fields in this Template Record.  Because a 
           Template Set usually contains multiple Template Records, 
           this field allows the Collecting Process to determine the 
           end of the current Template Record and the start of the 
           next. 
            
     Field Type 
           A numeric value that represents the type of the field.  
           Refer to [IPFIX-INFO]. 
               
     Field Length 
           The length of the corresponding Field Type, in bytes.  Refer 
           to [IPFIX-INFO]. 
            
      Enterprise Number  
           IANA enterprise number [PEN] of the authority defining the  
           Field Type. 
      
      Padding  
           The Exporting Process MAY insert some padding bytes, so that 
           the subsequent Set starts at an aligned boundary.  Padding 
           MUST be composed of zero (0) bytes.  The padding length MUST 
           be shorter than any allowable Template Record in this 
           Template Set.  It is important to note that the Length field 
           includes the padding bytes.  Because Template Sets are 
           always 4-byte aligned by definition padding is only needed 
           in case of other alignments e.g. on 8-byte boundaries. 
            
   The Set ID value of 0 and 1 are not used for historical reasons 
   [NETFLOW9]. 
    
 6.4      Data Set Format 
    
   The format of the Data Set is shown in Figure I. 
    
    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
 
 
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   |   Set ID = Template ID        |          Length               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 1 - Field Value 1    |   Record 1 - Field Value 2    | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 1 - Field Value 3    |             ...               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 2 - Field Value 1    |   Record 2 - Field Value 2    | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 2 - Field Value 3    |             ...               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 3 - Field Value 1    |             ...               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |              ...              |        Padding (opt)          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   
    
      Figure I: Data Set Format 
    
   Note that not all Field Values do necessarily have a length of 16 
   bit. 
    
   Data Set Field Descriptions are as follows: 
    
   Set ID = Template ID 
           Each Data Set is associated with a Set ID.  The Set ID maps 
           to a (previously generated) Template ID.  The Collecting 
           Process MUST use the Set ID to find the corresponding 
           Template Record and decode the Flow Records from the Set. 
            
   Length 
           The length of this Set.   
           Length is the sum total of lengths of Set ID, Length itself, 
           all Flow Records within this Set, and the padding bytes, if 
           any. 
                  
   Record N - Field Value M 
           The remainder of the Data Set is a collection of Flow Data 
           Record(s), each containing a set of Field Types and values.  
           The Type and Length of the fields have been previously 
           defined in the Template Record referenced by the Set ID or 
           Template ID. 
            
   Padding  

 
 
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           The Exporting Process MAY insert some padding bytes, so that 
           the subsequent Set starts at an aligned boundary.  Padding 
           MUST be composed of zero (0) bytes.  The padding length MUST 
           be shorter than any allowable Flow Data Record in this Data 
           Set.  It is important to note that the Length field includes 
           the padding bytes. 
    
   Interpretation of the Data Set format can be done only if the 
   Template Set corresponding to the Template ID is available at the 
   Collecting Process.    
    
 6.5      Options Template Set 
    
   The Options Template Record (and its corresponding Options Data 
   Record) is used to supply information about the Metering Process 
   configuration or Metering Process specific data, rather than 
   supplying information about IP Flows. 
    
   For example, the Options Template Set can report the sample rate of 
   a specific interface, if sampling is supported, along with the 
   sampling method used.   

 6.5.1   Scope 
    
   The Options Template Set gives the Exporter the ability to provide 
   additional information to the Collector which would not be possible 
   with only Flow Records. The scope, which is only available in the 
   Options Template Set, gives the context of the reported Information 
   Elements.  One Options Template Set example is the "Metering Process 
   statistics", which reports the statistics for the Observation 
   Domain, which is defined as the scope.  Another example is the 
   "Template configuration", which reports the configuration sampling 
   parameter(s) for the template, which is defined as the scope.   
    
   Multiple scope fields MAY be present in the Options Template Set, in 
   which, the composite scope is the combination of the scopes. For 
   example, if the two scopes are defined as "cache" and "template", 
   the combined scope is this template in this cache.  The order of the 
   scope, as defined in the Options Template Set, is in this case 
   irrelevant. However, if the order of the scopes fields in the Option 
   Template Set is relevant, the order of the scope fields MUST be 
   used.  For example, if the first scope defines the filtering 
   function, while the second scope defines the sampling function, the 
 
 
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   order of the scope is important. Applying first the sampling 
   function, followed by the filtering function, would lead to 
   potential different Flow Records than applying first the filtering 
   function, followed by the filtering function.  In this case, the 
   Collector deduces the function order by looking at the order of the 
   scope in the Options Template Set.  
    
   Finally, note that the scope length MAY NOT be zero. 

 6.5.2   Options Template Set Format 
    
   An Options Template MAY exclusively contain IETF defined Field 
   Types.  An Options Template MAY contain Enterprise Specific 
   Information Elements from multiple vendors.  An Options Template MAY 
   contain IETF defined Field Types and Enterprise Specific Information 
   Elements. 
    
   The format of the Options Template Set is shown in Figure J.   
    
       0                   1                   2                   3  
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |          Set ID = 3           |          Length               |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |         Template ID           |         Field Count           |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |      Scope Field Count        |      Scope 1 Field Type       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |     Scope 1 Field Length      |      Scope 2 Field Type       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |     Scope 2 Field Length      |             ...               |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |            ...                |      Scope N Field Type       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     Scope N Field Length      |   Scope N Entreprise Number ... 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
     ...  Scope N Enterprise Number   |      Option 1 Field Type      |       
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |    Option 1 Field Length      |  Option 1 Entreprise Number ... 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
     ... Option 1 Enterprise Number   |              ...              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |             ...               |       Option M Field Type     |  
 
 
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |     Option M Field Length     |         Padding (opt)         |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    
      Figure J: Option Template Set Format 
    
   The Options Template Set Field Definitions are as follows: 
    
   Set ID = 3 
           A Set ID value of 3 is reserved for the Options Template. 
    
   Length 
           Total length of this Set, including the padding bytes, if 
           any.  Each Options Template Set MAY contain multiple Options 
           Template Records.  Thus, the Length value MUST be used to 
           determine the position of the next Set record, which could 
           be either a Template Set or Data Set.                 
           Length is the sum total of lengths of Set ID, the Length 
           itself, and all Options Template Records within this Set 
           Template ID. 
    
   Template ID 
           Template ID of this Options Template.  This value is greater 
           than 255. 
     
   Field Count  
           Number of all fields in this Option Template Record, 
           including the Scope Fields.  Because a Option Template Set 
           usually contains multiple Template Records, this field 
           allows the Collecting Process to determine the end of the 
           current Option Template Record and the start of the next.  
 
   Scope Field Count  
           Number of scope fields in this Option Template Record.  
    
   Scope Field Type 
           A numeric value that represents the type of the field.  
           Refer to [IPFIX-INFO]. 
            
   Scope Field Length 
           The length (in bytes) of the Scope field, as it would appear 
           in an Options Data Record. 
            
 
 
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   Scope N Enterprise Number  
           IANA enterprise number [PEN] of the authority defining  
           Scope N Field Type. This is 4 bytes long. 
    
   Option Field Type 
           A numeric value that represents the type of field.  Refer to 
           [IPFIX-INFO]. 
            
   Option Field Length 
           The length of the corresponding Option Field Type, in bytes.  
           Refer to [IPFIX-INFO]. 
            
    Option M Enterprise Number  
           IANA enterprise number [PEN] of the authority defining the 
           Option M Field Type. This is 4 bytes long. 
            
   Padding  
           The Exporting Process MAY insert some padding bytes, so that 
           the subsequent Set starts at an aligned boundary.  Padding 
           MUST be composed of zero (0) bytes.  The padding length MUST 
           be shorter than any allowable Options Template Record in 
           this Options Template Set.  It is important to note that the 
           Length field includes the padding bytes. 
    
   The Set ID value of 0 and 1 are not used for historical reasons 
   [NETFLOW9]. 

 6.5.3   Options Data Record Format 
    
   The Options Data Records are sent in Data Sets. 
    
   The format of the Data Set, containing Options Data Records, is 
   shown in Figure K.   
    
    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |      Set ID = Template ID     |          Length               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 1 - Scope 1 Value    |   Record 1 - Scope 2 Value    | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |              ...              |Record 1 - Option Field 1 Value| 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
 
 
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   |Record 1 - Option Field 2 Value|             ...               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 2 - Scope 1 Value    |   Record 2 - Scope 2 Value    | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |              ...              |Record 2 - Option Field 1 Value| 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |Record 2 - Option Field 2 Value|             ...               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Record 3 - Scope 1 Value    |   Record 3 - Scope 2 Value    | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |              ...              |Record 3 - Option Field 1 Value| 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |Record 3 - Option Field 2 Value|             ...               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |              ...              |         Padding (opt)         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
      Figure K: Data Set format, containing Options Data Records  
    
   Options Data Records of the Data Set Field Descriptions  
    
   Set ID = Template ID 
           A Set ID precedes each group of Options Data Records within 
           a Data Set.  The Set ID maps to a previously generated 
           Template ID corresponding to this Options Template Record.  
           The Collecting Process MUST use the Set ID to map the 
           appropriate type and length to any field values that follow. 
            
   Length 
           The length of this Set.    
           Length is the sum of the lengths of the Set ID, Length 
           itself, all the Options Data Records within this Set, and 
           the padding bytes, if any. 
            
   Record N - Option Field M Value 
           The remainder of the Data Set is a collection of Flow 
           Records, each containing a set of Scope and Field Values.  
           The type and length of the fields were previously defined in 
           the Options Template Record referenced by the Set ID or 
           Template ID. 
            
   Padding  

 
 
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           The Exporting Process MAY insert some padding bytes, so that 
           the subsequent Set starts at an aligned boundary.  Padding 
           MUST be composed of zero (0) bytes.  The padding length MUST 
           be shorter than any allowable Options Data Record in this 
           Data Set.  It is important to note that the Length field 
           includes the padding bytes. 
            
   The Data Set format can be interpreted only if the Options Template 
   Set corresponding to the Template ID is available at the Collecting 
   Process. 
    
 7.     Specific Reporting Requirements 
 
   Some specific Options Templates and Options Templates Records are 
   necessary to provide extra information about the Flow Records and 
   about the Metering Process.    
        
   The ipfixOption Field [IPFIX-INFO], always included in these 
   specific Options Templates, defines the type of information sent in 
   the Option Template / Option Template Record pair.  For example, if 
   the ipfixOption [IPFIX-INFO] value is METER_STATS, then the Option 
   Template will specify information about the Metering Process 
   statistics.  
    
   The Option Template and Option Template Records defined in these 
   sub-sections are not mandatory to implement as they impose some 
   constraints about the Metering Process implementation: this document 
   specifies the protocol to export the records, not the Metering 
   Process implementation.  However, if the specific Option Templates 
   are implemented, they should ideally be implemented as specified in 
   these sub-sections.  In any case, if the ipfixOption Information 
   Element is present, it MUST always be the first Information Element 
   in the Option Template so that the Collector can quickly determine 
   which specific Option Template Record is received. 
         
   The minimum set of Information Elements is always specified in these 
   Specific IPFIX Options Templates.  Nevertheless, extra Information 
   Elements may be used in these specific Options Templates.     
    
 7.1      The Metering Process Statistics Option Template 
  



 
 
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   The Metering Process Statistics Option Template specifies the 
   Metering Process Statistics. It contains the following Information 
   Elements [IPFIX-INFO]:  
        ipfixOption             The value is METERING_STATS  
        exportedOctetCount      The number of all octets reported  
                                by the Exporting Process to the 
                                Collecting Process. 
        exportedPacketCount     The number of all packets reported  
                                by the exporting process to the 
                                Collecting Process. 
        exportedFlowCount       The number of all flows records  
                                reported by the Exporting Process 
                                to the Collecting Process.  
        time                    The time at which the record was 
                                generated  
     
   The Exporting Process should export the Metering Process Statistics 
   Option Template Record on a regular basis or based on some export 
   policy.  This periodicity or export policy should be configurable. 
   The Metering Process Statistics Option Template could be extended 
   with other Information Elements. 
    
   The Scope Field specified in the Metering Process Statistics Option 
   Template Record is the Source ID. 
    
 7.2      The Metering Process Reliability Statistics Option Template 
  
   The Metering Process Reliability Option Template specifies 
   information about lack of reliability in the Metering process.  It 
   contains the following Information Elements [IPFIX-INFO]: 
    
        ipfixOption             The value is METERING_RELIABILITY_STATS 
        droppedFUPacketCount    Packets dropped by Metering Process 
        droppedFUOctetCount     Bytes dropped by Metering Process  
        timeFirstFUDropped      Time of the first packet dropped at the  
                                Specified scope ID 
        timeLastFUDropped       Time of the last packet dropped at the  
                                Specified scope ID 
        time                    The time at which the record was  
                                generated  
    
   The Exporting Process should export the Metering Process Reliability 
   Statistics Option Template Record on a regular basis or based on 
 
 
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   some export policy.  This periodicity or export policy should be 
   configurable. The Metering Process Reliability Statistics Option 
   Template could be extended with other Information Elements. 
    
   The Scope Field specified in the Metering Process Reliability 
   Statistics Option Template Record is the Source ID. 
    
 7.3      The Exporting Process Reliability Statistics Option Template 
  
   The Exporting Process Reliability Option Template specifies 
   information about lack of reliability in the Exporting process.  It 
   contains the following Information Elements [IPFIX-INFO]: 
    
        ipfixOption             The value is  
                                EXPORTING_RELIABILITY_STATS 
        droppedFlows            Number of flow records not exported  
                                (due to resources starvation at  
                                Exporting Process or due to some 
                                flow records export policies) 
        droppedFAPacketCount    Packets in the dropped flows 
        droppedFAByteCount      Bytes in the dropped flows 
        timeFirstFADropped      Time of the first packet within the  
                                dropped flows 
        timeLastFADropped       Time of the last packet within the  
                                dropped flows 
        time                    The time at which the record was  
                                generated  
    
   The Exporting Process should export the Exporting Process 
   Reliability Statistics Option Template Record on a regular basis or 
   based on some export policy.  This periodicity or export policy 
   should be configurable. The Exporting Process Reliability Statistics 
   Option Template could be extended with other Information Elements. 
    
   The Scope Field specified in the Exporter Reliability Statistics 
   Option Template Record is the Exporter ID. 
    
 7.4      The Flow Keys Option Template 
    
   The Flow Keys Option Template specifies the flow keys used by the 
   Metering Process for the Template ID definition. It contains the 
   following Information Elements [IPFIX-INFO]: 
    
 
 
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        ipfixOption             The value is FLOW_KEY 
        keyList                 Bitmap with the positions of the flow  
                                keys in the template 
        time                    The time at which the record was  
                                generated  
    
   The Scope Field specified in the Flow Keys Option Template Record is 
   the Template ID with which the flow keys are associated. 
 
 8.     "Export Time" Computation and Flow Record Time 
    
 8.1      Microsecond Precision 
    
   For a Data Set with Flow Records requiring microsecond precision, 
   the IPFIX Message Header "Export Time" field MUST be calculated so 
   that each Flow Records flowStartUsec [IPFIX-INFO] and flowEndUsec 
   [IPFIX-INFO] would contain a 32 bit signed microsecond offset from 
   the "Export Time" base timestamp.  Hereafter some pseudo code to 
   calculate the Export Time in one pass, which would return an 
   absolute duration of 35 minutes for all Flow Records contained in 
   the Data Set.  Flow Records MUST be exported in different IPFIX 
   Message Header if the absolute durations can not fit in those 35 
   minutes. 
    
   //  pseudo code for microsecond offset in IPFIX encoded Flow 
   Records. 
   // 
    
   struct flow{ 
      uint32  tv_sec; 
      uint32  tv_usec; 
      uint32  numbytes; 
      ...  // other Information Elements... 
   }; 
    
   struct flow flowtable [MAX_TABLE_SIZE]; 
   int lastflowindex = -1; 
    
   writeflows() { 
      if (lastflowindex < 0) return; 
      // simply take the second field from the first available flow    
      // and make this the base time for this collection of flows.     
      uint32  base_sec = flowtable[0].tv_sec; 

 
 
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      writeheaderToSocket(base_sec); // put 32-bit second value in   
                                        header 
      for (int i=0; i<=lastflowindex; i++){ 
         int32 offset = (flowtable[i].tv_sec - base_sec) * 1000000  
                        + flowtable[i].tv_usec; 
         writeint32ToSocket(offset);  // put the 32-bit time offset  
                                         in the record. 
         // write other Information Elements... 
       } 
   } 
    
   A two pass approach calculation for the optimum (center) "Export 
   Time" base timestamp would allow an absolute duration of 71 minutes 
   for all Flow Records contained in the Data Set.  The two pass 
   approach MAY be used.  The "Export Time" base timestamp calculation 
   requires that at the IPFIX Message Header exporting time the 
   Exporting Process MUST run down the list of Flow Records in the Data 
   Set message and adjust the Flow start and Flow end timestamps. 
    
 8.2      Millisecond Precision 
    
   For a Data Set with Flow Records requiring a millisecond precision, 
   the same principles as in section 9.1 "Microsecond Precision" will 
   be used. 
    
   The only difference will be that the Flow start and the Flow end 
   SHOULD now be represented respectively by the flowStartMsec [IPFIX-
   INFO] and flowEndMsec [IPFIX-INFO].  As a consequence of the 
   millisecond precision, the absolute duration of all Flow Records is 
   now of about 49 days.  The Export header "Export Time" base time 
   SHOULD be calculated with the algorithm described in the Section 9.1 
   "Microsecond Precision".  In order to reduce the load on the 
   Exporter, the Export header "Export Time" MAY be the time in seconds 
   since 0000 UTC 1970 at which the IPFIX Message Header leaves the 
   Exporter and not the calculated optimum value anymore as described 
   in section 9.1 "Microsecond Precision". 
    
   Alternatively, for a Data Set with Flow Records requiring a 
   millisecond precision, the microsecond mechanism as described in 
   section 9.1 MAY be used as such.  The Flow Record MAY use the 
   flowStartUsec [IPFIX-INFO] and flowEndUsec [IPFIX-INFO] rounded at a 
   millisecond precision.   
    
 
 
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 8.3      Nanosecond Precision 
    
   For a Data Set with Flow Records requiring a nanosecond precision, 
   all Flow Records will contain Flow start flowStartNsec [IPFIX-INFO] 
   and flowEndNsec [IPFIX-INFO].  The Export header "Export Time" will 
   be of no use on the Collector side in this case as the flowStartNsec 
   [IPFIX-INFO] and flowEndNsec [IPFIX-INFO] both have a nanosecond 
   precision already.  Both flowStartNsec [IPFIX-INFO] and flowEndNsec 
   [IPFIX-INFO] use the NTP time format which is represented as a 64-
   bit value which contains a 32-bit specification of seconds since 
   1900 and a 32-bit "fraction" field.   Refer to the NTP 
   specification, RFC1305, section 3.1 "Data Formats". 
    
 8.4      Multiple Precisions 
     
   When Flow Records requiring different precisions must be exported, 
   the Exporting Process SHOULD split the Flow Records in different 
   Data Set according to the precision: millisecond, microsecond or 
   nanosecond. 
    
 9.     Linkage with the Information Model 
 
   The Information Elements [IPFIX-INFO] MUST be sent in canonical 
   format in network byte order. 
    
 9.1      Reduced Size Encoding of Integer Types 
 
   Information Elements containing integer types in the information 
   model MAY be encoded using fewer bytes than those implied by their 
   type in the information model definition [IPFIX-INFO], based on the 
   assumption that the smaller type is sufficient to carry any value 
   the Exporter may need to deliver.  This reduces the network 
   bandwidth requirement between the Exporter and the Collector.  Note 
   that the Information Elements definition [IPFIX-INFO] will always 
   define the maximum encoding size. 
    
   For instance the information model [IPFIX-INFO] defines byteCount as 
   an unsignedLong type, which would require 64-bits.  However if the 
   Exporter will never locally encounter the need to send a value 
   larger than 4294967295, it may chose to send the value instead as an 
   unsignedInt.  For example, a core router would require an 
   unsignedLong byteCount while an unsignedInt might be sufficient for 
   an access router. 
    
 
 
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   This behavior is indicated by the Exporter by specifying a type size 
   smaller than that associated with the assigned type of the field.  
   In the example above the Exporter would place a length of 4 versus 8 
   in the template. 
    
   If reduced sizing is used, it MUST be applied only to following 
   integer types: unsignedLong, long, unsignedInt, int, unsignedShort, 
   short.  In each case the downcasting MUST be to a smaller integer 
   type.  The same signed versus unsigned properties MUST be preserved. 
   Specifically unsignedLong may be downcast to unsignedInt, 
   unsignedShort or unsignedByte.  A long may be downcast to an int, a 
   short or a byte.  The other downcasts follow the same pattern. 
    
 10.      Variable Length Information Element 
 
   The IPFIX template mechanism is optimized for fixed length 
   Information Elements [IPFIX-INFO].  Where an Information Element has 
   a variable length the following mechanism MUST used to carry the 
   length information, for both the IETF and proprietary Information 
   Elements. 
    
   In the Template Set the length is recorded as 65535.  This reserved 
   length value notifies the Collecting Process that length of the 
   Information Element will be carried in the Information Element 
   content itself. 
    
   In most cases the length of the Information Element will be less 
   than 256 bytes.  The following length encoding mechanism optimizes 
   the overhead of carrying the Information Element length in this 
   majority case. 
    
   If the length of the Information Element is less than 255 bytes, the 
   length is carried in the first byte of the Information Element, as 
   shown on Figure L. 
       0                   1                   2                   3 
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | Length (< 255)|          Information element                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                      ... continuing as needed                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
     Figure L: Variable Length Information Element (length < 255 bytes) 
 
 
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   If the length of the Information Element is greater or equal than 
   255 bytes, the first byte of the Information Element is 255, and the 
   length is carried in the second and third bytes of the Information 
   Element, as shown in Figure M. 
       0                   1                   2                   3 
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |        Length (255 to 65535)       |   IE     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                      ... continuing as needed                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
      Figure M: Variable Length Information Element  
               (length 255 to 65535) bytes 
    
 11.      Template Management 
  
              
   This section describes Template management when using SCTP and SCTP-
   PR as the transport protocol. Any necessary changes to Template 
   management specifically related to TCP or UDP transport protocols 
   are specified in section 13.  
                     
   The Exporting Process assigns and maintains the Template IDs for the 
   ExporterÆs Observations Domains. A newly created Template Record is 
   assigned an unused Template ID by the Exporting Process.   
                     
   Templates Sets and Option Template Sets MUST be only sent once on 
   SCTP stream zero with full reliability.  As such, the Collecting 
   Process MUST store the Template Record information for the duration 
   of the association so that it can interpret the corresponding Flow 
   Data Records that are received in subsequent Data Sets.  
                     
   New Template Records SHOULD be transmitted as soon as they are 
   created. The Exporting Process MAY transmit the Template Set and 
   Options Template in advance of any Data Sets that use that (Options) 
   Template ID, to ensure that the Collector has the Template Record 
   before receiving the first Flow or Options Data Record.  Flow and 
   Options Data Records that correspond to a Template Record MAY appear 
   in the same and/or subsequent IPFIX Message(s).    
                 


 
 
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   A Template ID MUST be unique per Observation Domain. Different 
   Observation Domains from the same Exporter may use the same Template 
   ID value to refer to different Templates.  
    
   Disused Templates SHOULD be deleted. Prior to reuse a Template ID 
   the disused Template MUST be deleted.  In order to delete an 
   allocated Template, the Template is withdrawn through the use of a 
   Template Withdraw Message.  
    
   The Template Withdraw Message MUST not be sent until sufficient time 
   has elapsed to allow the Collecting Process to receive and process 
   the last data record using this Template information.  
    
   The Template ID from a withdrawn Template MUST NOT be reused until 
   sufficient time has elapsed to allow for the Collecting Process to 
   receive and process the Template withdraw message.  
    
   A Template Withdraw Message is Template Record for that Template ID 
   with a Field Count of 0. The format of the Template Withdrawal 
   Message is shown in figure O.  
    
      0                   1                   2                   3     
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
     |       Set ID = (2 or 3)       |          Length = 8           |  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
     |          Template ID          |        Field Count = 0        |  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    
           Figure O: Template Withdrawal Message format  
    
   The Set ID field MUST contain the value 2 for Template Set 
   withdrawal, and the value 3 for Options Template Set.  Multiple 
   Template ID MAY be withdrawn with a single Template Withdrawal 
   Message: in that case, padding MAY be used. 
   The Template Withdraw Message withdraws the Template ID for the 
   Source ID specified in the IPFIX Message header. 
              
   If the measurement parameters change, the Template MUST be withdrawn 
   using a Template Withdraw Message or an unused Template ID MUST be 
   used. Examples of the measurement changes are: a new sampling rate, 
   a new flow expiration process, a new filtering definition, etc. If a 

 
 
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   Template is changed, a Template Withdraw Message MUST be sent to 
   delete the Template.   
                     
   If the Exporting Process restarts, the SCTP association MUST be 
   shutdown and restarted. When the Exporting Process restarts, all 
   Template assignments are lost and Template IDs MUST be re-assigned. 
   If the Metering Process restarts, the Exporting Process MUST either 
   reuse the previously assigned Template ID for each Template, or it 
   MUST withdraw the previously issued Template IDs by sending Template 
   Withdraw Message(s) before reusing them.  A Template Withdrawal 
   Message to withdraw all Data Templates for the Source ID specified 
   in the IPFIX message header MAY be used. Its format is shown in 
   figure P. A Template Withdrawal Message to withdraw all Options 
   Templates for the Source ID specified in the IPFIX message header 
   MAY be used. Its format is shown in figure Q. 
    
      0                   1                   2                   3     
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |             Set ID = 2        |          Length = 8           | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
     |         Template ID = 2       |        Field Count = 0        |  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
           Figure P: All Data Templates Withdrawal Message format  
    
      0                   1                   2                   3     
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |             Set ID = 3        |          Length = 8           | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
     |         Template ID = 3       |        Field Count = 0        |  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
           Figure Q: All Options Templates Withdrawal Message format  
    
   When the SCTP association restarts, the Exporting Process MUST 
   resend all the Template Records.  
                     
   The Exporting Process MUST NOT transmit IPFIX Messages with more 
   than one Source ID value inside any single stream.  
                     
   More that one (Option) Template Set MAY be sent in an IPFIX Message.   
 
 
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 12.      The Collecting Process's Side 
    
   This section describes the Collecting Process when using SCTP and 
   SCTP-PR as the transport protocol. Any necessary changes to the 
   Collecting Process specifically related to TCP or UDP transport 
   protocols are specified in section 13.  
                     
   The Collecting Process SHOULD listen for a new association request 
   from the Exporting Process.  The Exporting Process will request a 
   number of streams to use for export.  A Collecting Process MUST 
   support at least two inbound streams per association.  An Exporting 
   Process MAY ask for and support more than two streams.  
                     
   The Collecting Process MUST verify that only one Source ID value is 
   used inside each stream. If the Collecting Process detects that more 
   than one Source ID has been received within a stream, it MUST 
   discard the IPFIX Message, reset the SCTP association, and SHOULD 
   log the error  
                     
   If the Collecting Process receives a malformed IPFIX Message, it 
   MUST reset the SCTP association, discard the IPFIX Message, and 
   SHOULD log the error.   
                     
   Templates Sets and Option Template Sets are only sent once.  The 
   Collecting Process MUST store the Template Record information for 
   the duration of the association so that it can interpret the 
   corresponding Flow Data Records that are received in subsequent Data 
   Sets.  
                     
   Template IDs are unique per Exporting Process and per Observation 
   Domain.  If the Collecting Process receives a Template which has 
   already been received but which has not previously been withdrawn 
   (i.e. a Template Record from the same Exporter Observation Domain 
   with the same Template ID), then the Collecting Process MUST 
   shutdown the association.  
                      
   When an SCTP association is closed, the Collecting Process MUST 
   discard all templates received over that association and stop 
   decoding IPFIX Messages that use those templates.  
                     
   The Collecting Process normally receives Template Records from the 
   Exporting Process, before receiving Flow or Options Data Records.  
 
 
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   The Flow Data Records (or Options Data Records) are then decoded and 
   stored by the Collector. If the Template Records have not been 
   received at the time Flow Data Records (or Options Data Records) are 
   received, the Collecting Process MAY store the Flow Data Records (or 
   Options Data Records) for a short period of time and decode them 
   after the Template Records are received.  A Collecting Process MUST 
   NOT assume that the Data Set and the associated Template Set (or 
   Options Template Set) are exported in the same IPFIX Message.  
                     
   The Collecting Process MUST note the Field ID of any Information 
   Element that it does not understand and MAY discard that Information 
   Element from the Flow Record.  The Collecting Process MUST note the 
   size and position of any Vendor Specified Information Element that 
   it does not understand and discard that Information Element from the 
   Flow Record.  
                     
   More that one (Options) Template Set MAY be received in an IPFIX 
   Message.  
                 
   The Collector MUST accept padding in Flow Data Records, Options Data 
   Records and Template Records.  
                     
   The IPFIX protocol has a Sequence Number field in the Export header 
   which increases with each IPFIX Message.  A Collector may detect out 
   of sequence, dropped, or duplicate IPFIX Messages by tracking the 
   Sequence Number.  EDITORÆS NOTE: THIS MIGHT CHANGE IF THE SEQUENCE 
   NUMBER IS PER STREAM AND IF THIS IS THE NUMBER OF FLOW RECORDS. A 
   collector SHOULD provide a logging mechanism for tracking out of 
   sequence IPFIX Messages.  Such out of sequence IPFIX Messages may be 
   due to Exporter resource exhaustion where it can not transmit 
   messages at their creation rate, an Exporting Process reset, 
   congestion on the network link between the Exporter and Collector, 
   Collector resource exhaustion where it can not process the IPFIX 
   Messages at their arrival rate, out of order packet reception, 
   duplicate packet reception, or an attacker injecting false messages.  
                     
   If a Collecting Process receives a Template Withdraw Message, the 
   Collecting Process MUST delete the corresponding Template Record 
   associated with the specific Exporter and specific Observation 
   Domain, and stop decoding IPFIX Messages that use those Templates.   
                 
   A Collecting Process that receives IPFIX Messages from several 
   Observation Domains from the same Exporter MUST be aware that the 
 
 
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   uniqueness of the Template ID is not guaranteed across Observation 
   Domains.  
    
   IPFIX Messages with a Source ID of zero MUST be discarded by the  
   Collecting Process. 
 
 13.      Transport Protocol 
    
   The IPFIX Protocol Specification has been designed to be transport 
   protocol independent.  Note that the Exporter can export to multiple 
   Collecting Processes, using independent transport protocols. 
    
   The IPFIX Message Header 16-bit LENGTH field limits the length of a 
   IPFIX Message to 65536 octets including the header.  A Collecting 
   Process MUST be able to handle IPFIX Message lengths of up to 65536 
   octets. 
    
 13.1       Transport Compliance and Transport Usage 
 
   We need to differentiate between what must be implemented (so that 
   operators can interoperably deploy compliant implementations from 
   different vendors) and what should or could be used in various 
   operational environments. We must also make sure that ALL 
   implementations can operate in a congestion-aware and congestion 
   avoiding mode. 
    
   SCTP [RFC2960] and SCTP-PR [RFC3758] MUST be implemented by all 
   compliant implementations.  UDP [UDP] MAY also be implemented by 
   compliant implementations.  TCP [TCP] MAY also be implemented by 
   compliant implementations.  
    
   SCTP-PR SHOULD be used in deployments where Exporters and Collectors 
   are communicating over links that are susceptible to congestion.  
   SCTP-PR is capable of providing any required degree of reliability. 
    
   TCP MAY be used in deployments where Exporters and Collectors 
   communicate over links that are susceptible to congestion, but SCTP-
   PR is preferred, due to its ability to limit back pressure on 
   Exporters and its message versus stream orientation.  
    
   UDP MAY be used although it is not a congestion aware protocol.  
   However, the IPFIX traffic between Exporter and Collector MUST 
   remain wholly within the administrative domains of the operators. 
    
 
 
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 13.2      TCP 
    
   This section describes how IPFIX can be transported over TCP [TCP].  

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

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

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

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

 13.2.4.1 Connection Establishment 
    
   The IPFIX Exporting Process initiates a TCP connection to the IPFIX 
   Collecting Process.  By default, the Collecting Process listens for 
   connections on TCP port XXXX (to be assigned by IANA).  It MUST be 
   possible to configure both the Exporting and Collecting Processes to 
   use a different TCP port.  
    
   An Exporting Process MAY support more than one active connection to 
   different Collecting Processes (including the case of different 
   Collecting Processes on the same host).  

 
 
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 13.2.4.2 Connection Release 
    
   When an Exporting Process has no more IPFIX Messages to send, it 
   SHOULD close the TCP connection.  
    
   When a Collecting Process no longer wants to receive IPFIX messages, 
   it SHOULD close the TCP connection, but SHOULD continue to receive 
   and process IPFIX messages until the Exporting Process has closed 
   its end.  
    
   When an Collecting Process detects that the TCP connection to the 
   Exporting Process is abnormally terminated, it MUST continue to 
   listen for a new connection.  
    
   When an Exporting Process detects that the TCP connection is 
   abnormally terminated, it SHOULD try to re-establish the connection.  
    
   Connection timeouts SHOULD be configurable.  

 13.2.4.3 IPFIX Message Encoding 
    
   TCP provides message boundary marking marking mechanism. When IPFIX 
   Message are sent over a TCP connection, the LENGTH field in the 
   IPFIX Message header defines the end of each message and the start 
   of the next message.  
    
   If an Exporting Process exports data from multiple Observation 
   Domains, it should be careful to choose the IPFIX Message lengths 
   appropriately to avoid head-of-line blocking between different 
   Observation Domains. 

 13.2.5  Template Management 
    
   New Template Records SHOULD be transmitted as soon as they are 
   created on the Metering Process, and preferably before any 
   associated Flow or  Options Data Record is transmitted.  The 
   Collecting Process SHOULD accept Flow and Options Data Records 
   without the associated Template Record.   
                     
   A Collecting Process MUST record all Template and Option Template 
   Records for the duration of the connection, as an Exporting Process 
   is not required to re-export Template Records.   

 
 
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 13.2.6  Fail-over 
    
   If the Collecting Process does not acknowledge the attempt by the 
   Exporting Process to establish a connection, the Exporting Process 
   should retry. The retry schedule SHOULD be configurable.  In the 
   default configuration, an Exporting Process MUST NOT attempt to 
   establish a connection more frequently than once per minute.  
    
   The Exporter MAY log an alarm if the time to establish the 
   association exceeds a specified threshold.  
    
   If Collecting Process fail-over is supported by the Exporting 
   Process a second TCP connection MAY be opened in advance. 
    
 13.3       SCTP 
 
   This section describes how IPFIX can be transported over SCTP 
   [RFC2960] using the PR-SCTP [RFC3758] extension.    

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

 13.3.2  Reliability 
 
   The SCTP transport protocol is by default reliable, but has the 
   capability to operate in unreliable and partially reliable modes 
   [RFC3758]. 
    
   Using reliable SCTP streams (referred to hereafter as "streams") for 
   the IPFIX export is not in itself a guarantee that all data records 
   are delivered.  If there is congestion on the link from the 
 
 
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   Exporting Process to the Collecting Process, or if a significant 
   number of retransmissions are required, the send queues on the 
   Exporting Process may fill up: the Exporting Process MAY either 
   suspend export or discard IPFIX Messages.  If data records are 
   discarded the sequence numbers used for export MUST reflect the loss 
   of data.   

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

 13.3.4  Exporting Process 

 13.3.4.1 Association Establishment 
    
   The IPFIX Exporting Process SHOULD initiate an SCTP association with 
   the IPFIX Collecting Process.  By default, the Collecting Process 
   listens for connections on SCTP port XXXX (to be assigned by 
   IANA).  It MUST be possible to configure both the Exporting 
   and Collecting Processes to use a different SCTP port. 
    
   The Exporting Process MAY establish more than one associations 
   (connection "bundle" in SCTP terminology) to the Collecting Process. 
    
   An Exporting Process MAY support more than one active association 
   to different Collecting Processes (including the case of different 
   Collecting Processes on the same host). 
    

 13.3.4.2 Association Shutdown 
    
   When an Exporting Process has no more IPFIX Messages to send, it 
   SHOULD shutdown the SCTP association. 
    
   When a Collecting Process no longer wants to receive IPFIX 
   Messages, it SHOULD shutdown its end of the association.  The 
   Collecting Process SHOULD continue to receive and process 
   IPFIX Messages until the Exporting Process has closed its end. 
    
   When a Collecting Process detects that the SCTP association has been 
   abnormally terminated, it MUST continue to listen for a new 
   association establishment. 
 
 
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   When an Exporting Process detects that the SCTP association to the 
   Collecting Process is abnormally terminated, it SHOULD try to re-
   establish the association.  
    
   Association timeouts SHOULD be configurable. 
    

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

 13.3.4.4 Stream 
 
   An Exporting Process MUST request at least two outbound streams per 
   association.  The first stream (referred to as stream zero in the 
   rest of this document), is used to send the Template Set and the 
   Options Template Set.  Stream zero MUST be fully reliable.  Data 
   Sets MUST NOT be sent on stream zero. 
    
   Depending on the application requirement, the Exporting Process 
   selects the mode (unreliable, partially reliable, or fully reliable 
   mode) of the stream, used to send the Data Sets.  Unreliable mode 
   MAY be used where the application does not require reliable 
   transmission and the use of a retransmission queue is impractical. 
    
   An Exporter MAY use multiple streams to export Data Sets, in some 
   cases different applications will have different requirements in 
   terms of reliability.  In such a case, the Observation Domain MUST 
   use the same Source ID value on all of the multiple streams it uses.  
   Data Sets from multiple Observation Domains MUST NOT be transmitted 
   over the same stream; the Collecting Process should however verify 
   that the Source ID values are the expected values.   
    
   When Data Sets are exported over a partially reliable stream, they 
   SHOULD be marked for retransmission as long as there is room in the 
   SCTP send queues.  However during times of congestion or other 
   retransmission events, if the queue overflows, the oldest data 
   record that has been transmitted and marked as partially reliable 
   should be freed and marked to be skipped per the PR-SCTP [RFC3758] 
 
 
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   specification.  The freed buffer space should then be re-used for 
   the new Data Sets being exported.   

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

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

 13.3.6  Failover 
 
   If the Collecting Process does not acknowledge the attempt by the 
   Exporting Process to establish an association it will retry using 
   the SCTP exponential backoff feature.  The Exporter MAY log an alarm 
   if the time to establish the association exceeds a specified 
   threshold. 
    
   If Collecting Process failover is supported by the Exporting Process 
   a second SCTP association MAY be opened in advance. 
    
 13.4       UDP 
    
   This section describes how IPFIX can be transported over UDP  
   [RFC768] 

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

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

 
 
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   UDP MUST NOT be used unless the application can tolerate some  
   loss of Messages. 
    
   The Collecting Process could deduce the loss and reordering of IPFIX 
   Messages by looking at the discontinuities in the IPFIX Message 
   sequence number.  These conditions SHOULD be logged. 
    
   Templates sent from the Exporting Process to the Collecting  
   Process using UDP as a transport MUST be resent at regular  
   intervals in case previous copies were lost.  Implementations  
   MAY send templates using a reliable transport protocol, and  
   send IPFIX Flow and Option Data Records using UDP as the  
   transport protocol. 

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

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

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

 13.4.6  Template Management 
   When IPFIX uses UDP as the transport protocol, Template Sets and 
   Option Template Sets MUST be re-sent at regular intervals.  The 
   frequency of (Options) Template transmission MUST be configurable.  
   New Template Records SHOULD be transmitted as soon as they are 
   created, and SHOULD be transmitted before any associated Data  
   Record is transmitted.  
                 
   In the event of configuration changes, the Exporting Process SHOULD 
   send the new template definitions at an accelerated rate.  In such a 
   case, it MAY transmit the changed Template Record(s) and Options 
   Template Record(s), without any data, in advance to help ensure that 

 
 
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   the Collector will have the correct template information before 
   receiving the first data.  
                     
   If the Option Template scope is defined in another Template, then 
   both Templates SHOULD be sent in the same IPFIX Message. For 
   example: if a Flow Key Option Template (see section 8.3) is sent in 
   an Option Template, then the associated Template SHOULD be sent in 
   the same IPFIX Message.  
                     
   Note that following a configuration change a new Template ID should 
   be used and the old Template ID SHOULD NOT be reused until its 
   lifetime has expired.  
                     
   Template Withdraw Messages SHOULD NOT be sent over UDP.             

 13.4.7   Collecting Process 
    
   The Collecting Process SHOULD accept Flow and Options Data Records 
   without the associated Template Record. If the Template Records have 
   not been received at the time Flow Data Records (or Options Data 
   Records) are received, the Collecting Process SHOULD store the Flow 
   Data Records (or Options Data Records) for a short period of time 
   and decode them after the (Options) Template Records are received.  
   The short period of time MUST be lower than the Template lifetime.  
                     
   The lifetime of a template at the Collecting Process is limited to a 
   fixed refresh timeout.  The Collecting Process MUST associate a 
   lifetime with each Template received via UDP.  Templates not 
   refreshed by the Exporting Process within the timeout are expired at 
   the Collecting Process.  If the template is not refreshed by the 
   Exporting Process before that lifetime has expired, the Collecting 
   Process MUST discard the Template, and any current and future 
   associated Flow or Option Data Records.  The Collecting Process MUST 
   NOT decode any further Flow or Option Data Records which are 
   associated with that expired Template.   
                      
   At any given time the Collecting Process SHOULD maintain the 
   following for all the current Template Records and Options Template 
   Records: <Exporting Process, Observation Domain, Template ID, 
   Template Definition, Last Received>.  
    


 
 
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 13.4.8  Failover 
    
   Because UDP is not a connection oriented protocol, the Exporting 
   Process is unable to determine from the transport protocol that the 
   Collecting Process is no longer able to receive the IFPIX Messages.  
   Therefore, it can not invoke a failover mechanism.  However, the 
   Exporting Process MAY duplicate the IPFIX Message to several 
   Collecting Processes. 
    
 14.      Security Considerations 
 
   Because IPFIX can be used to collect billing information and network 
   forensics, confusing or blinding IPFIX must be seen as a prime  
   objective during a sophisticated network attack.   
    
   If an attacker is in a position to inject false messages into an 
   IPFIX Message stream this will allow them to send forged Flow Data 
   Records, Options Data Records, or Templates.  Forged Templates may 
   impair the Collectors ability to process any further Flow Records.  
   Forged Flow Records would have a direct effect on the application 
   using the Flows, for example a billing system may generate incorrect 
   billing information.  Forged options may be able to alter the 
   meaning of Flow Records, for example if the sample rate is changed.   
    
   The IPFIX Messages themselves may contain information of value to an 
   attacker, and thus care must be taken to confine their visibility to 
   authorized users.   
    
   IPFIX Messages can be secured using IPsec.  Alternatively if IPFIX 
   runs on top of SCTP or TCP, TLS [TLS] can be used. 
    
   When an Information Element containing end-user payload information 
   is exported, it SHOULD be transmitted to the Collecting Process 
   using a means that secures its contents against eavesdropping. 
   Suitable mechanisms include the use of either a direct point-to-
   point connection or the use of an encryption mechanism. It is the 
   responsibility of the Collecting Process to provide a satisfactory 
   degree of security for this collected data, including, if necessary, 
   anonymization of any reported data. 
    
 14.1       IPsec Usage 
    
   To secure messages between the Exporter and the Collector an IPFIX 
 
 
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   implementation MAY use IPsec.  To ensure interworking between 
   Exporters and Collectors from different vendors, the following IPsec 
   profile MUST be supported.  This profile is derived from [USEIPSEC]. 

 14.1.1  Selectors 
    
   IPFIX runs between manually configured pairs of hosts on the 
   following transport ports (TBD).  The appropriate selector would be 
   Exporter-Collector pairs and port number.   
    
   Note that, if the Exporter is a router, a non-interface ("loopback") 
   address should be used.    

 14.1.2  Mode 
    
   IPsec MUST be run in transport mode.  The AH and ESP MUST be 
   supported by an IPFIX implementation of IPsec.   
    
   The Authentication Header (AH) [RFC2402] MUST be used if 
   authentication is required.  The Security Protocol (ESP) [RFC2406] 
   must be used if there is a threat to the IPFIX Message content, or 
   if that content is confidential.   
    
   Normally in situations where the ESP was required the AH would also 
   be required.  If ESP only is used, the sender's IP address MUST be 
   checked against the IP address asserted in the key management 
   exchange. 

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

 14.1.4  Security Policy 
 
   Connections should be accepted only from the designated peer. 

 14.1.5  Authentication 
 

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

 14.1.6  Availability 
    
   It is accepted that IPsec will not be universally available in IPFIX 
   Exporters, and that where it is available, there may be issues of 
   throughput, which may itself raise security issues.  In such 
   circumstances the other security measures described in this document 
   provide some threat mitigation.   
    
 14.2       TLS Usage 
     
   The IPFIX Exporter initiating a connection acts as a TLS client 
   according to [TLS], and an IPFIX Collector that accepts a connection 
   acts as a TLS server.  If mutual authentication is required the 
   IPFIX Device acting as TLS server MUST request a certificate from 
   the IPFIX Device acting as TLS client, and the IPFIX Device acting 
   as TLS client MUST be prepared to supply a certificate on request. 
    
 14.3       Protection against DoS attacks 
    
   An attacker may directly mount a DoS attack by generating large 
   amounts of traffic.   If TCP is used for transport, then the Flow to 
   the Collector would back off due to congestion and eventually stall, 
   blinding the IPFIX system.  An attack could then proceed without 
   further observation.  SCTP-PR will have a different pathology under 
   such an attack.  Stale data at the head of the queue will get 
   flushed giving some visibility of the attack.  In case of UDP, IPFIX 
   would reduce to some sort of sampling, meaning that some forensics 
   may be left.   
    
   To avoid blinding of the IPFIX system some mechanism for service 
   differentiation can be used to prioritize IPFIX traffic over user 
   traffic.  An alternative is to use a dedicated network for the 
   transport of IPFIX Messages.  By sending the IPFIX Messages over a 
   dedicated network, IPFIX Message loss induced by user traffic 
   congestion is minimized.  However an attacker may trigger the 
   generation of excessive IPFIX Messages, and to avoid information 
   loss during such an attack the IPFIX network must be adequately 
   sized. 
 
 
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 14.4       When IPsec or TLS is not an option 
    
   The use of IPsec or TLS might not be an option because of 
   performance issues. 
    
   Without IPsec or TLS an IPFIX entity has no means to authenticate an 
   IPFIX entity other than the Source IP address.  Useful protection is 
   gained by allocating Exporter and Collector IP addresses from ranges 
   that are excluded from use by user traffic and preventing spoofing 
   attacks by proper ingress filtering.  Where large numbers of 
   Exporters, proxies and Collectors are used in a network, it may be 
   tempting for the administrator to not impose source IP address 
   restrictions but this leaves a proxy or Collector open to the 
   reception of invalid information.  Using an open proxy or Collector 
   is therefore discouraged.   
    
   If IP address spoofing can not be prevented some level of protection 
   against an insertion attack is required.  With a modern 
   implementation of TCP with good ISN randomization [XXX-REFERENCE] or 
   SCTP insertion such attacks are difficult without the ability to 
   snoop the packet Flow [XXX-SCTP-BLIND-SPOOFING-REFERENCE].  UDP is 
   vulnerable to insertion attacks, however, randomization of the IPFIX 
   Sequence Number might mitigate this problem.  In all these cases, 
   the Sequence Number space is relatively small giving only limited 
   protection.  Therefore a 64 bit cookie [L2TPv3] SHOULD be included 
   as an element within all messages.   
    
   The use of a dedicated network prevents IPFIX Messages from being 
   inspected by an attacker. 
    
 14.5       Logging an IPFIX Attack 
 
   A Collector may detect problems by tracking the IPFIX Sequence 
   Number and therefore SHOULD provide a logging mechanism for tracking 
   out of sequence messages.  Such out of sequence messages may not 
   only be caused by network congestion or Exporter/Collector resource 
   exhaustion but also by an attacker injecting false messages.   
    
   Note that an attacker may be able to exploit the behavior of the 
   Collector when it receives an out of sequence message.  For example 
   a Collector that simply reset the expected Sequence Number upon 
   receipt of a later message would easily be temporarily blinded by 

 
 
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   deliberately injecting messages with a much larger Sequence Number.   
    
   [EDITOR NOTE: the security section may need be adapted to the 
   revised transport section]   
    
 15.      IANA Considerations 
    
   The IPFIX Protocol, as set out in this document, has two sets of 
   assigned numbers.  Considerations for assigning them are discussed 
   in this section, using the example policies as set out in the 
   "Guidelines for IANA Considerations" document IANA-RFC [RFC2434]. 
    
 15.1       Numbers used in the Protocol 
    
   IPFIX Messages use two fields with assigned values.  These are the 
   IPFIX Version Number, indicating which version of the IPFIX Protocol 
   was used to export an IPFIX Message, and the IPFIX Set ID, 
   indicating the type for each set of information within an IPFIX 
   Message. 
    
   Changes in either IPFIX Version Number or IPFIX Set ID assignments 
   require an IETF Consensus, i.e. they are to be made via RFCs 
   approved by the IESG. 
    
 15.2       Numbers used in the Information Model 
    
   Fields of the IPFIX protocol carry information about traffic 
   measurement. They are modeled as elements of the IPFIX information 
   model [IPFIX-INFO]. Each Information Element describes a field which 
   may appear in an IPFIX Message. Within an IPFIX Message the field 
   type is indicated by its Field Type. 
    
   New assignments for IPFIX Field Types will be administered by IANA, 
   on First Come First Serve basis [RFC 2434] , subject to Expert 
   Review [RFC 2434], i.e. review by one of a group of experts 
   designated by an IETF Operations and Management Area Director. The 
   group of experts must double check the Information Elements 
   definitions for completeness, accuracy and redundancy with already 
   defined Information Elements. Those experts will initially be drawn 
   from the Working Group Chairs and document editors of the IPFIX and 
   PSAMP Working Groups. The IANA assignments for IPFIX Field Types 
   will range from 128 to 32767; the values below 128 are reserved or 


 
 
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   assigned already; the values ranging from 32768 to 65535 are 
   allocated for private use by vendors. 
    
 16.      Examples 
    
   Let's consider the example of an IPFIX Message composed of a  
   Template Set, a Data Set (which contains three Flow Data Records), 
   an Options Template Set and a Data Set (which contains 2 Options 
   Data Records).   
    
   IPFIX Message: 
    
   +--------+---------------------------------------------. . . 
   |        | +--------------+ +-----------------------+  
   |Message | | Template     | | Data                  |  
   | Header | | Set          | | Set                   |   . . . 
   |        | | (1 Template) | | (3 Flow Data Records) |  
   |        | +--------------+ +-----------------------+  
   +--------+---------------------------------------------. . . 
 
        . . .+-------------------------------------------------+ 
             +------------------+ +--------------------------+ | 
             | Options          | | Data                     | | 
        . . .| Template Set     | | Set                      | | 
             | (1 Template)     | | (2 Options Data Records) | | 
             +------------------+ +--------------------------+ | 
        . . .--------------------------------------------------+ 
    
 16.1       Message Header Example 
    
   The Message Header is composed of: 
    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     Version = 0x000a          |         Length = 152          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          Export Time                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                       Sequence Number                         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                           Source ID                           | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

 
 
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 16.2       Template Set Examples 

 16.2.1  Template Set using IETF specified Information Elements  
    
   We want to report the following Field Types: 
   - The source IP address (IPv4), so the length is 4 
   - The destination IP address (IPv4), so the length is 4 
   - The next-hop IP address (IPv4), so the length is 4 
   - The number of bytes of the Flow 
   - The number of packets of the Flow 
    
   Therefore, the Template Set will be composed of the following: 
    
    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |         Set ID = 2            |      Length = 28 bytes        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |       Template ID 256         |       Field Count = 5         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     IP_SRC_ADDR = 0x0008      |       Field Length = 4        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     IP_DST_ADDR = 0x000C      |       Field Length = 4        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     IP_NEXT_HOP = 0x000F      |       Field Length = 4        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |       IN_PKTS = 0x0002        |       Field Length = 4        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |       IN_BYTES = 0x0001       |       Field Length = 4        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
 

 16.2.2  Template Set using Enterprise Specific Information Elements  
    
      We want to report the following Field Types:  
      - The source IP address (IPv4), so the length is 4  
      - The destination IP address (IPv4), so the length is 4  
      - An Enterprise Specific Field representing proprietary  
        information, with a type of 0x000F and a length of 4  
      - The number of bytes of the Flow  
      - The number of packets of the Flow  
    
      Therefore, the Template Set will be composed of the following:  
 
 
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       0                   1                   2                   3  
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |         Set ID = 2            |      Length = 28 bytes        |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       Template ID 256         |       Field Count = 5         |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |     IP_SRC_ADDR = 0x0008      |       Field Length = 4        |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |     IP_DST_ADDR = 0x000C      |       Field Length = 4        |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |1| Enterprise Field Type=0x000F|       Field Length = 4        |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |                       Enterprise number                       |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       IN_PKTS = 0x0002        |       Field Length = 4        |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
      |       IN_BYTES = 0x0001       |       Field Length = 4        |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
 16.3       Data Set Example 
 
   In this example, we report the following three Flow Records: 
   Src IP addr. | Dst IP addr.  | Next Hop addr. | Packet | Bytes  
                |               |                | Number | Number 
   ------------------------------------------------------------------ 
   192.168.1.12 | 192.168.2.254 | 192.168.1.1    | 5009   | 5344385 
   192.168.1.27 | 192.168.2.23  | 192.168.1.2    | 748    | 388934 
   192.168.1.56 | 192.168.2.65  | 192.168.1.3    | 5      | 6534 
    
    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |          Set ID = 256         |          Length = 64          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.1.12                         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.2.254                        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.1.1                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                             5009                              | 
 
 
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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                            5344385                            |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.1.27                         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.2.23                         |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.1.2                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                              748                              | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                             388934                            | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.1.56                         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.2.65                         | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                          192.168.1.3                          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                               5                               | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                              6534                             | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
   Note that padding is not necessary in this example. 
    
 16.4       Options Template Set Examples 

 16.4.1  Options Template Set using IETF specified Information Elements   
    
   Per line card (the router being composed of two line cards), we want 
   to report the following Field Types:  
      - Total number of IPFIX Messages  
      - Total number of exported Flows  
    
   Each line card is characterized by an unique Observation Domain, 
   represented by the unique Source ID Information Elements [IPFIX- 
   INFO]. As a consequence, the Scope Field is the Source ID 
   Information Element. 
    
   Therefore, the Options Template Set will be: 
    
    0                   1                   2                   3 
 
 
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    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |         Set ID = 3            |          Length = 24          | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |       Template ID 257         |        Field Count = 3        | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |     Scope Field Count = 1     | Scope 1 Field Type = 141      | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Scope 1 Field Length = 4    |    TOTAL_EXP_PKTS_SENT = 41   | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |       Field Length = 4        |     TOTAL_FLOWS_EXP = 42      | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |       Field Length = 4        |           Padding             | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

 16.4.2  Options Template Set using Enterprise Specific Information 
     Elements 
   Per line card (the router being composed of two line cards), we want  
   to report the following Field Types:  
      - Total number of IPFIX Messages  
      - An Enterprise Specific number of exported Flows,  
        with a type of 42 and a length of 4  
 
   Each line card is characterized by an unique Observation Domain,  
   represented by the unique Source ID Information Elements [IPFIX-  
   INFO]. As a consequence, the Scope Field is the Source ID  
   Information Element.  
 
   The format of the Options Template Set is as follows:  
 
    0                   1                   2                   3  
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |         Set ID = 3            |          Length = 24          |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |       Template ID 257         |        Field Count = 3        |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |     Scope Field Count = 1     |   Scope 1 Field Type = 141    |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |   Scope 1 Field Length = 4    |    TOTAL_EXP_PKTS_SENT = 41   |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |       Field Length = 4        |1| Enterprise Field Type = 42  |  
 
 
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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |       Field Length = 4        |       Enterprise number      ...  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
  ...      Enterprise number       |           Padding             |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

 16.4.3  Options Template Set using an Enterprise Specific scope 
   In this example, we want to export the same information as in the  
  example in section 16.4.2:  
      - Total number of IPFIX Messages  
      - Total number of exported Flows  
 
   But this time, the information pertains to a proprietary scope,  
   identified by Enterprise Specific Information Element number 123.  
 
   The format of the Options Template Set is now as follows:  
 
    0                   1                   2                   3  
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |         Set ID = 3            |          Length = 28          |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |       Template ID 257         |        Field Count = 3        |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |     Scope Field Count = 1     |1|  Scope 1 Field Type = 123   |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |                      Enterprise Number                        |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |   Scope 1 Field Length = 4    |    TOTAL_EXP_PKTS_SENT = 41   |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |       Field Length = 4        |     TOTAL_FLOWS_EXP = 42      |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
   |       Field Length = 4        |           Padding             |  
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    
 16.5       Data Set with Options Data Records Example 
    
   In this example, we report the following two Options Data Records: 
   Line Card ID             | IPFIX Message   | Exported Flow Records 
   ------------------------------------------------------------------ 
   Line Card 1 (SourceID=1) | 345             | 10201     
   Line Card 2 (SourceID=2) | 690             | 20402 
 
 
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   0                   1                   2                   3  
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    |      Set ID = 257             |         Length = 20           |  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    |                               1                               | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |             345               |            10201              | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    |                               2                               |  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    |             690               |            20402              |  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    
 17.     References 
    
 17.1       Normative References 
    
   [IPFIX-ARCH] Sadasivan, G, Brownlee, N. "Architecture Model for IP 
   Flow Information Export" draft-ietf-ipfix-arch-02.txt", October 2003 
    
   [IPFIX-INFO] Calato, P, Meyer, J, Quittek, J, "Information Model for 
   IP Flow Information Export" draft-ietf-ipfix-info-02, November 2003 
    
   [UDP]  Postel, J., "User Datagram Protocol" RFC 768, August 1980 
    
   [TCP]  "TRANSMISSION CONTROL PROTOCOL DARPA INTERNET PROGRAM 
   PROTOCOL SPECIFICATION" RFC 793, September 1981 
    
   [RFC1889] Schulzrinne, H., Casner, S., Frederick, R., Jacobson, V., 
   "RTP: A Transport Protocol for Real-Time Applications ", RFC 1889, 
   January 1996 
    
   [RFC2434] Alvestrand, H. and T. Narten, "Guidelines for Writing an 
   IANA Considerations Section in RFCs", RFC 2434, October 1998. 
    
   [RFC2402] Kent, S., Atkinson, R., "IP Authentication Header ", RFC 
   2402, November 1998  
    
   [RFC2406] Kent, S., Atkinson, R., "IP Encapsulating Security Payload 
   (ESP)", RFC 2406, November 1998  
    
 
 
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   [RFC2960] Stewart, R. (ed.) "Stream Control Transmission Protocol", 
   RFC 2960, October 2000 
    
   [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., Conrad, P.  
   "Stream Control Transmission Protocol (SCTP) Partial Reliability 
   Extension", RFC 3758, May 2004 
 
 17.2       Informative References 
 
   [IPFIX-REQ] Quittek, J, Zseby, T, Claise, B, Zander, S,  
   "Requirements for IP Flow Information Export" draft-ietf-ipfix-reqs-
   15.txt, June 2003 
    
   [IPFIX-AS] Zseby, T, Penno, R, Brownlee, N, Claise, B, "IPFIX 
   Applicability", draft-ietf-ipfix-as-01.txt, October 2003      
              
   [IPFIX-EVAL] Leinen, S, "Evaluation of Candidate Protocols for IP 
   Flow Information Export (IPFIX)", draft-leinen-ipfix-eval-contrib-
   02.txt, January 2003 
    
   [NETFLOW9] Claise, B, et al "Cisco Systems NetFlow Services Export 
   Version 9", draft-claise-netflow-9-07.txt, December 2003 
    
   [PEN] IANA Private Enterprise Numbers registry 
         http://www.iana.org/assignments/enterprise-numbers  
    
   [USEIPSEC] S. Bellovin, Guidelines for Mandating the Use of IPsec,  
              draft-bellovin-useipsec-02.txt, October 2003, work  
              in progress.  
    
   [IKE]      Harkins, D. and D. Carrel, "The Internet Key Exchange  
              (IKE)", RFC 2409, November 1998. 
    
   [TLS]      Dierks, T. and C. Allen, "The TLS Protocol Version  
              1.0", RFC 2246, January 1999. 
    
   [L2TPv3]   J. Lau et al. Layer Two Tunneling Protocol (Version 3)  
              draft-ietf-l2tpext-l2tp-base-11.txt, October 2003, work  
              in progress.  
    
   [XXX-REFERENCE]  
    
   [XXX-SCTP-BLIND-SPOOFING-REFERENCE] 
 
 
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 18.      Acknowledgments 
    
   We would like to thank the following persons: Juergen Quittek for 
   the coordination job; Nevil Brownlee and Dave Plonka for the 
   thorough reviews; Randall Stewart and Peter Lei for their SCTP 
   expertise;  Martin Djernaes for the first essay on the SCTP section; 
   Simon Leinen for the first essay on the TCP section Sebastian 
   Zander, Jeff Meyer, Maurizio Molina, Carter Bullard, Tal Givoly, and 
   many more, for the technical feedback. 
    
 Authors Addresses 
 
   Benoit Claise 
   Cisco Systems 
   De Kleetlaan 6a b1 
   1831 Diegem 
   Belgium 
   Phone: +32 2 704 5622 
   E-mail: bclaise@cisco.com 
 
   Stewart Bryant 
   Cisco Systems, Inc. 
   250, Longwater, 
   Green Park, 
   Reading, RG2 6GB, 
   United Kingdom 
   Phone: +44 (0)20 8824-8828             
   Email: stbryant@cisco.com 
    
   Ganesh Sadasivan 
   Cisco Systems, Inc. 
   170 W. Tasman Dr. 
   San Jose, CA 95134 
   USA 
   Phone: +1 (408) 527-0251 
   Email: gsadasiv@cisco.com 
    
   Mark Fullmer 
   OARnet 
   2455 North Star Rd. 
   Columbus, Ohio 43221 
   Phone: +1 (614) 728-8100 

 
 
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                   IPFIX Protocol Specification          December 2004 
 
 
   Email: maf@eng.oar.net 
    
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