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Export of Structured Data in IP Flow Information Export (IPFIX)
draft-ietf-ipfix-structured-data-06

The information below is for an old version of the document that is already published as an RFC.
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This is an older version of an Internet-Draft that was ultimately published as RFC 6313.
Authors Benoît Claise , Stan Yates , Gowri Dhandapani , Paul Aitken
Last updated 2020-01-21 (Latest revision 2011-05-03)
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draft-ietf-ipfix-structured-data-06
IPFIX Working Group                                    B. Claise 
     Internet-Draft                                     G. Dhandapani 
     Update: RFC5102                                        P. Aitken 
     Intended Status: Standards Track                        S. Yates   
     Expires: November 3, 2011                    Cisco Systems, Inc. 
                                                          May 3, 2011 
      
                        Export of Structured Data in IPFIX 
                     draft-ietf-ipfix-structured-data-06.txt 

     Status of this Memo 

        This Internet-Draft is submitted to IETF in full conformance 
        with the provisions of BCP 78 and BCP 79.  
         
        Internet-Drafts are working documents of the Internet 
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        This Internet-Draft will expire on September, 2011. 
         

         
         
                                                                         
                             


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     Copyright Notice 
         
        Copyright (c) 2011 IETF Trust and the persons identified as the 
        document authors.  All rights reserved. 
         
        This document is subject to BCP 78 and the IETF Trust's Legal 
        Provisions Relating to IETF Documents 
        (http://trustee.ietf.org/license-info) in effect on the date of 
        publication of this document.  Please review these documents 
        carefully, as they describe your rights and restrictions with 
        respect to this document.  Code Components extracted from this 
        document must include Simplified BSD License text as described 
        in Section 4.e of the Trust Legal Provisions and are provided 
        without warranty as described in the Simplified BSD License. 
                            
      

     Abstract 

        This document specifies an extension to the IP Flow Information 
        eXport (IPFIX) protocol specification in [RFC5101] and the IPFIX 
        information model specified in [RFC5102] to support hierarchical 
        structured data and lists (sequences) of Information Elements in 
        data records.  This extension allows definition of complex data 
        structures such as variable-length lists and specification of 
        hierarchical containment relationships between Templates. 
        Finally, the semantics are provided in order to express the 
        relationship among multiple list elements in a structured data 
        record. 
         
         
     Conventions used in this document 

        The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL 
        NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and 
        "OPTIONAL" in this document are to be interpreted as described 
        in RFC 2119 [RFC2119]. 
      

      
      
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     Table of Contents 

         
        1. Overview...................................................7 
           1.1. IPFIX Documents Overview..............................7 
           1.2. Relationship between IPFIX and PSAMP..................8 
        2. Introduction...............................................8 
           2.1. The IPFIX Track.......................................9 
           2.2. The IPFIX Limitations................................10 
           2.3. Structured Data Use Cases............................10 
           2.4. Specifications Summary...............................12 
        3. Terminology...............................................13 
           3.1. New Terminology......................................13 
        4. Linkage with the IPFIX Information Model..................13 
           4.1. New Abstract Data Types..............................14 
              4.1.1. basicList.......................................14 
              4.1.2. subTemplateList.................................14 
              4.1.3. subTemplateMultiList............................14 
           4.2. New Data Type Semantic...............................14 
              4.2.1. List............................................15 
           4.3. New Information Elements.............................15
              4.3.1. basicList.......................................15 
              4.3.2. subTemplateList.................................15 
              4.3.3. subTemplateMultiList............................15 
           4.4. New Structured Data Type Semantics...................16 
              4.4.1. undefined.......................................16 
              4.4.2. noneOf..........................................16 
              4.4.3. exactlyOneOf....................................17 
              4.4.4. oneOrMoreOf.....................................18 
              4.4.5. allOf...........................................18 
              4.4.6. ordered.........................................19 
           4.5. Encoding of IPFIX Data Types.........................19 
              4.5.1. basicList.......................................19 
              4.5.2. subTemplateList.................................22 
              4.5.3. subTemplateMultiList............................24 
        5. Structured Data Format....................................28 
           5.1. Length Encoding Considerations.......................29 
           5.2. Recursive Structured Data............................29 
           5.3. Structured Data Information Elements Applicability in 
           Options Template Sets.....................................30 
           5.4. Usage Guidelines for Equivalent Data Representations.31 
           5.5. Padding..............................................32 
           5.6. Semantic.............................................32 
        6. Template Management.......................................36 
        7. The Collecting Process's Side.............................37 
        8. Defining New Information Elements Based on the New 
        Abstract Data Types..........................................38 
      
      
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        9. Structured Data Encoding Examples.........................38 
           9.1. Encoding a Multicast Data Record with basicList......38 
           9.2. Encoding a Load-balanced Data Record with a basicList40 
           9.3. Encoding subTemplateList.............................41 
           9.4. Encoding subTemplateMultiList........................44 
           9.5. Encoding an Options Template Set using Structured 
           Data......................................................49 
        10. Relationship with the Other IFPIX Documents..............54 
           10.1. Relationship with Reducing Redundancy...............54 
              10.1.1. Encoding Structured Data Element using Common 
              Properties.............................................54 
              10.1.2. Encoding Common Properties elements With 
              Structured Data Information Element....................54 
           10.2. Relationship with Guidelines for IPFIX Testing......56 
           10.3. Relationship with IPFIX Mediation Function..........57 
        11. IANA Considerations......................................57 
           11.1. New Abstract Data Types.............................58 
              11.1.1. basicList......................................58 
              11.1.2. subTemplateList................................58 
              11.1.3. subTemplateMultiList...........................58 
           11.2. New Data Type Semantics.............................58 
              11.2.1. list...........................................59 
           11.3. New Information Elements............................59 
              11.3.1. basicList......................................59 
              11.3.2. subTemplateList................................59 
              11.3.3. subTemplateMultiList...........................60 
           11.4. New Structured Data Semantics.......................60 
              11.4.1. undefined......................................60 
              11.4.2. noneOf.........................................60 
              11.4.3. exactlyOneOf...................................61 
              11.4.4. oneOrMoreOf....................................61 
              11.4.5. allOf..........................................61 
              11.4.6. ordered........................................61 
        12. Security Considerations..................................62 
        13. References...............................................62 
           13.1. Normative References................................62 
           13.2. Informative References..............................62 
        14. Acknowledgement..........................................63 
        15. Authors' Addresses.......................................64 
        Appendix A.  Additions to XML Specification of IPFIX 
        Information Elements and Abstract Data Types.................65
        Appendix B.  Encoding IPS Alert using Structured Data 
        Information Elements.........................................70 
         
      

      
      
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     Table of Figures 

     Figure A: basicList Encoding...................................19
     Figure B: basicList Encoding with Enterprise Number............21
     Figure C: Variable-Length basicList Encoding (Length < 255 octets)
         ...........................................................21
     Figure D: Variable-Length basicList Encoding (Length 0 to 65535 
        octets) ....................................................22
     Figure E: subTemplateList Encoding.............................22
     Figure F: Variable-Length subTemplateList Encoding (Length < 255 
        octets) ....................................................23
     Figure G: Variable-Length subTemplateList Encoding (Length 0 to 
        65535 octets) ..............................................24
     Figure H: subTemplateMultiList Encoding........................25
     Figure I: Variable-Length subTemplateMultiList Encoding (Length < 
        255 octets) ................................................27
     Figure J: Variable-Length subTemplateMultiList Encoding (Length 0 
        to 65535 octets) ...........................................28
     Figure K: Encoding basicList, Template Record..................39
     Figure L: Encoding basicList, Data Record, Semantic allOf......40
     Figure M: Encoding basicList, Data Record with Variable-Length 
        Elements, Semantic allOf ...................................40
     Figure N: Encoding basicList, Data Record, Semantic ExactlyOneOf
         ...........................................................41
     Figure O: Encoding subTemplateList, Template for One-Way Delay 
        Metrics ....................................................42
     Figure P: Encoding subTemplateList, Template Record............43
     Figure Q: Encoding subTemplateList, Data Set...................44
     Figure R: Encoding subTemplateMultiList, Template for Filtering 
        Attributes .................................................47
     Figure S: Encoding subTemplateMultiList, Template for Sampling 
        Attributes .................................................47
     Figure T: Encoding subTemplateMultiList, Template for Flow Record
         ...........................................................48
     Figure U: Encoding subTemplateMultiList, Data Set..............49
     Note that the example could further be improved with a basicList  
        of selectorId if many Selector IDs have to be reported. ....51
     Figure V: PSAMP SSRI to be encoded.............................51
     Figure W: Options Template Record for PSAMP SSRI using 
        subTemplateMultiList .......................................51
     Figure X: PSAMP SSRI, Template Record for interface............52
     Figure Y: PSAMP SSRI, Template Record for linecard.............52
     Figure Z: PSAMP SSRI, Template Record for linecard and interface
         ...........................................................52
     Figure ZA: Example of a PSAMP SSRI Data Record, Encoded using a 
        subTemplateMultiList .......................................53
     Figure ZB: Common and Specific Properties Exported Together 
        [RFC5473] ..................................................55
     Figure ZC: Common and Specific Properties Exported Separately  
        according to [RFC5473] .....................................55
      
      
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     Figure ZD: Common and Specific Properties Exported with Structured 
        Data Information Element ...................................55
     Figure B0: Encoding IPS Alert, Template for Target.............72
     Figure B1: Encoding IPS Alert, Template for Attacker...........72
     Figure B2: Encoding IPS Alert, Template for Participant........73
     Figure B3: Encoding IPS Alert, Template for IPS Alert..........73
     Figure B4: Encoding IPS Alert, Data Set........................75
                          

      
      
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     1. Overview 

     1.1. IPFIX Documents Overview 

      The IPFIX Protocol [RFC5101] provides network administrators with 
      access to IP Flow information. 
       
      The architecture for the export of measured IP Flow information 
      out of an IPFIX Exporting Process to a Collecting Process is 
      defined in the IPFIX Architecture [RFC5470], per the requirements 
      defined in RFC 3917 [RFC3917]. 
       
      The IPFIX Architecture [RFC5470] specifies how IPFIX Data Records 
      and Templates are carried via a congestion-aware transport 
      protocol from IPFIX Exporting Processes to IPFIX Collecting 
      Processes. 
       
      IPFIX has a formal description of IPFIX Information Elements, 
      their name, type and additional semantic information, as specified 
      in the IPFIX information model [RFC5102]. 
       
      In order to gain a level of confidence in the IPFIX 
      implementation, probe the conformity and robustness, and allow 
      interoperability, the Guidelines for IPFIX Testing [RFC5471] 
      presents a list of tests for implementers of compliant Exporting 
      Processes and Collecting Processes. 
      
      The Bidirectional Flow Export [RFC5103] specifies a method for 
      exporting bidirectional flow (biflow) information using the IP 
      Flow Information Export (IPFIX) protocol, representing each Biflow 
      using a single Flow Record. 
       
      The "Reducing Redundancy in IP Flow Information Export (IPFIX) and 
      Packet Sampling (PSAMP) Reports" [RFC5473] specifies a bandwidth 
      saving method for exporting Flow or packet information, by 
      separating information common to several Flow Records from 
      information specific to an individual Flow Record: common Flow 
      information is exported only once. 
      
      

      
      
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     1.2. Relationship between IPFIX and PSAMP 

      The specification in this document applies to the IPFIX protocol 
      specifications [RFC5101].  All specifications from [RFC5101] apply 
      unless specified otherwise in this document. 
       
      The Packet Sampling (PSAMP) protocol [RFC5476] specifies the 
      export of packet information from a PSAMP Exporting Process to a 
      PSAMP Collecting Process.  Like IPFIX, PSAMP has a formal 
      description of its information elements, their name, type and 
      additional semantic information.  The PSAMP information model is 
      defined in [RFC5477]. 
      
      As the PSAMP protocol specifications [RFC5476] are based on the 
      IPFIX protocol specifications, the specifications in this document 
      are also valid for the PSAMP protocol.  
        
      Indeed, the major difference between IPFIX and PSAMP is that the 
      IPFIX protocol exports Flow Records while the PSAMP protocol 
      exports Packet Reports.  From a pure export point of view, IPFIX 
      will not distinguish a Flow Record composed of several packets 
      aggregated together, from a Flow Record composed of a single 
      packet.  So the PSAMP export can be seen as a special IPFIX Flow 
      Record containing information about a single packet. 
      
      
     2. Introduction 

     While collecting the interface counters every five minutes has 
     proven to be useful in the past, more and more granular 
     information is required from network elements for a series of 
     applications: performance assurance, capacity planning, security, 
     billing, or simply monitoring.  However, the amount of information 
     has become so large that, when dealing with highly granular 
     information such as Flow information, a push mechanism (as opposed 
     to a pull mechanism, such as SNMP) is the only solution for 
     routers whose primary function is to route packets.  Indeed, 
     polling short-lived Flows via SNMP is not an option: high end 
     routers can support hundreds of thousands of Flows simultaneously.  
     Furthermore, in order to reduce the export bandwidth requirements, 
     the network elements have to integrate mediation functions to 
     aggregate the collected information, both in space (typically from 
     different line cards or different Exporters) and in time. 
      
      Typically, it would be beneficial if access routers could export 
      Flow Records, composed of the counters before and after an 

      
      
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      optimization mechanism on the egress interface, instead of 
      exporting two Flow Records with identical tuple information. 
       
      In terms of aggregation in time, let us imagine that, for 
      performance assurance, the network management application must 
      receive the performance metrics associated with a specific flow, 
      every millisecond.  Since the performance metrics will be 
      constantly changing, there is a new dimension to the Flow 
      definition: we are not dealing anymore with a single Flow lasting 
      a few seconds or a few minutes, but with a multitude of one 
      millisecond sub flows for which the performance metrics are 
      reported. 
                        
      Which current protocol is suitable for these requirements: push 
      mechanism, highly granular information, and huge number of similar 
      records? IPFIX, as specified in RFC5101 would give part of the 
      solution. 
       
      
     2.1. The IPFIX Track 

      The IPFIX working group has specified a protocol to export Flow 
      information [RFC5101].  This protocol is designed to export 
      information about IP traffic Flows and related measurement data, 
      where a Flow is defined by a set of key attributes (e.g. source 
      and destination IP address, source and destination port, etc.).   
       
      The IPFIX protocol specification [RFC5101] specifies that traffic 
      measurements for Flows are exported using a TLV (type, length, 
      value) format.  The information is exported using a Template 
      Record that is sent once to export the {type, length} pairs that 
      define the data format for the Information Elements in a Flow.  
      The Data Records specify values for each Flow.   
       
      Based on the Requirements for IP Flow Information Export (IPFIX) 
      [RFC3917], the IPFIX protocol has been optimized to export Flow 
      related information.  However, thanks to its Template mechanism, 
      the IPFIX protocol can export any type of information, as long as 
      the relevant Information Element is specified in the IPFIX 
      information model [RFC5102], registered with IANA [IANA-IPFIX], or 
      specified as an enterprise-specific Information Element.  For each 
      Information Element, the IPFIX information model [RFC5102] defines 
      a numeric identifier, an abstract data type, an encoding mechanism 
      for the data type, and any semantic constraints.  Only basic, 
      single-valued data types, e.g., numbers, strings, and network 
      addresses are currently supported. 

      
      
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     2.2. The IPFIX Limitations 

      The IPFIX protocol specification [RFC5101] does not support the 
      encoding of hierarchical structured data and arbitrary-length 
      lists (sequences) of Information Elements as fields within a 
      Template Record.  As it is currently specified, a Data Record is a 
      "flat" list of single-valued attributes.  However, it is a common 
      data modeling requirement to compose complex hierarchies of data 
      types, with multiple occurrences, e.g., 0..* cardinality allowed 
      for instances of each Information Element in the hierarchy.  

      A typical example is the MPLS label stack entries model.  An early 
      NetFlow implementation used two Information Elements to represent 
      the MPLS label stack entry: a "label stack entry position" 
      followed by a "label stack value".  However, several drawbacks 
      were discovered.  Firstly, the Information Elements in the 
      Template Record had to be imposed so that the position would 
      always precede the value.  However, some encoding optimizations 
      are based on the permutation of Information Element order.  
      Secondly, a new semantic intelligence, not described in the 
      information model, had to be hardcoded in the Collecting Process: 
      the label value at the position "X" in the stack is contained in 
      the "label stack value" Information Element following by a "label 
      stack entry position" Information Element containing the value 
      "X".  Therefore, this model was abandoned. 
       
      The selected solution in the IPFIX information model [RFC5102] is 
      a long series of Information Elements: mplsTopLabelStackSection, 
      mplsLabelStackSection2, mplsLabelStackSection3, 
      mplsLabelStackSection4, mplsLabelStackSection5, 
      mplsLabelStackSection6, mplsLabelStackSection7, 
      mplsLabelStackSection8, mplsLabelStackSection9, 
      mplsLabelStackSection10.  While this model removes any ambiguity, 
      it overloads the IPFIX information model with repetitive 
      information.  Furthermore, if mplsLabelStackSection11 is required, 
      IANA [IANA-IPFIX] will not be able to assign the new Information 
      Element next to the other ones in the registry, which might cause 
      some confusion. 
      
     2.3. Structured Data Use Cases 

      Clearly the MPLS label stack entries issue can best be solved by 
      using a real structured data type composed of ("label stack entry 
      position", "label stack value") pairs, potentially repeated 
      multiple times in Flow Records, since this would be the most 
      efficient from an information model point of view. 
      
      
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      Some more examples enter the same category: how to encode the list 
      of output interfaces in a multicast Flow, how to encode the list 
      of BGP Autonomous Systems (AS) in a BGP Flow, how to encode the 
      BGP communities in a BGP Flow, etc?  
       
      The one-way delay passive measurement, which is described in the 
      IPFIX Applicability [RFC5472], is yet another example that would 
      benefit from a structured data encoding.  Assuming synchronized 
      clocks, the Collector can deduce the one-way delay between two 
      Observation Points from the following two Information Elements, 
      collected from two different Observation Points: 
          - Packet arrival time: observationTimeMicroseconds [RFC5477] 
          - Packet ID: digestHashValue [RFC5477] 
      In practice, this implies that many pairs of 
      (observationTimeMicroseconds, digestHashValue) must be exported 
      for each Observation Point, even if Hash-Based Filtering [RFC5475] 
      is used.  On top of that information, if the requirement is to 
      understand the one-way delay per application type, the 5-tuple 
      (source IP address, destination IP address, protocol, source port, 
      destination port) would need to be added to every Flow Record. 
      Instead of exporting this repetitive 5-tuple, as part of every 
      single Flow Record a Flow Record composed of a structured data 
      type such as the following would save a lot of bandwidth: 
       
          5-tuple 
                    { observationTimeMicroseconds 1, digestHashValue 1 } 
                    { observationTimeMicroseconds 2, digestHashValue 2 } 
                    { observationTimeMicroseconds 3, digestHashValue 3 } 
                    { ...  , ... } 
         
      As a last example, here is a more complex case of hierarchical 
      structured data encoding.  Consider the example scenario of an IPS 
      (Intrusion Prevention System) alert data structure containing 
      multiple participants, where each participant contains multiple 
      attackers and multiple targets, with each target potentially 
      composed of multiple applications, as depicted below: 
       
          alert 
              signatureId 
              protocolIdentifier 
              riskRating 
              participant 1 
                  attacker 1 
                      sourceIPv4Address 
                      applicationId 
      
      
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                  ... 
                  attacker N 
                      sourceIPv4Address 
                      applicationId 
                  target 1 
                      destinationIPv4Address 
                      applicationId 1 
                      ... 
                      applicationId n 
                  ... 
                  target N 
                      destinationIPv4Address 
                      applicationId 1 
                      ... 
                      applicationId n 
              participant 2 
                  ... 
       
      To export this information in IPFIX, the data would need to be 
      flattened (thus losing the hierarchical relationships) and a new 
      IPFIX Template created for each alert, according to the number of 
      applicationId elements in each target, the number of targets and 
      attackers in each participant, and the number of participants in 
      each alert.  Clearly each Template will be unique to each alert, 
      and a large amount of CPU, memory and export bandwidth will be 
      wasted creating, exporting, maintaining, and withdrawing the 
      Templates.  See Appendix B for a specific example related to this 
      case study. 
      
      
     2.4. Specifications Summary 

     This document specifies an IPFIX extension to support hierarchical 
     structured data and variable-length lists by defining three new 
     Information Elements and three corresponding new abstract data 
     types called basicList, subTemplateList, and subTemplateMultiList. 
     These are defined in Section 4.1.   
      
     The three Structured Data Information Elements carry some semantic 
     information so that the Collecting Process can understand the 
     relationship between the different list elements.  The semantic in 
     the Structured Data Information Elements is provided in order to 
     express the relationship among the multiple top-level list 
     elements.  As an example, if a list is composed of the elements 
      
      
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     (A,B,C), the semantic expresses the relationship among A, B, and 
     C, regardless of whether A, B, and C, are individual elements or 
     list of elements. 
      
     It is important to note that whereas the Information Elements and 
     abstract data types defined in the IPFIX information model 
     [RFC5102] represent single values, these new abstract data types 
     are structural in nature and primarily contain references to other 
     Information Elements and to Templates.  By referencing other 
     Information Elements and Templates from an Information Element's 
     data content, it is possible to define complex data structures 
     such as variable-length lists and to specify hierarchical 
     containment relationships between Templates.  Therefore, this 
     document prefers the more generic "Data Record" term to the "Flow 
     Record" term. 
      
     This document specifies three new abstract data types, which are 
     basic blocks to represent structured data.  However, this document 
     does not comment on all possible combinations of basicList, 
     subTemplateList, and subTemplateMultiList.  Neither, does it limit 
     the possible combinations. 
      
      
     3. Terminology 

      IPFIX-specific terminology used in this document is defined in 
      Section 2 of the IPFIX protocol specification [RFC5101] and 
      Section 3 of PSAMP protocol specification [RFC5476].  As in 
      [RFC5101], these IPFIX-specific terms have the first letter of a 
      word capitalized when used in this document. 
       
       
     3.1. New Terminology 

      Structured Data Information Element 
       
          One of the Information Elements supporting structured data, 
          i.e., the basicList, subTemplateList, or subTemplateMultiList 
          Information Elements specified in section 4.3.  
       
      
     4. Linkage with the IPFIX Information Model 

      As in the IPFIX Protocol specification [RFC5101], the new 
      Information Elements specified in Section 4.3. below MUST be sent 
      in canonical format in network-byte order (also known as the big-
      endian byte ordering). 
      
      
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     4.1. New Abstract Data Types 

      This document specifies three new abstract data types, as 
      described below. 
       
       
     4.1.1. basicList 

      The type "basicList" represents a list of zero or more instances 
      of any Information Element, primarily used for single-valued data 
      types.  For example, a list of port numbers, a list of interface 
      indexes, a list of AS in a BGP AS-PATH, etc.  
       
       
     4.1.2. subTemplateList 

      The type "subTemplateList" represents a list of zero or more 
      instances of a structured data type, where the data type of each 
      list element is the same and corresponds with a single Template 
      Record.  For example, a structured data type composed of multiple 
      pairs of ("MPLS label stack entry position", "MPLS label stack 
      value"), a structured data type composed of performance metrics, a 
      structured data type composed of multiple pairs of IP address, 
      etc. 
       
       
     4.1.3. subTemplateMultiList 

      The type "subTemplateMultiList" represents a list of zero or more 
      instances of a structured data type, where the data type of each 
      list element can be different and corresponds with different 
      template definitions.  For example, a structured data type 
      composed of multiple access-list entries, where entries can be 
      composed of different criteria types. 
       
       
     4.2. New Data Type Semantic 

      This document specifies a new data type semantic, in addition to 
      the ones specified in the section 3.2 of the IPFIX information 
      model [RFC5102], as described below.  
       

      
      
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     4.2.1. List 

      A list represents an arbitrary-length sequence of zero or more 
      structured data Information Elements, either composed of regular 
      Information Elements or composed of data conforming to a Template 
      Record. 
      
     4.3. New Information Elements 

      This document specifies three new Information Elements, as 
      described below. 
       
       
     4.3.1. basicList 

     A basicList specifies a generic Information Element with a 
     basicList abstract data type as defined in Section 4.1.1. and list 
     semantics as defined in Section 4.2.1.  For example, a list of 
     port numbers, a list of interface indexes, etc. 
      
      EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this 
      new Information Element identifier, the value XXX is used in all 
      the examples and in the XML in Appendix A. 
       
     4.3.2. subTemplateList 

      A subTemplateList specifies a generic Information Element with a 
      subTemplateList abstract data type as defined in Section 4.1.2. 
      and list semantics as defined in Section 4.2.1.  
       
      EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this 
      new Information Element identifier, the value YYY is used in all 
      the examples and in the XML in Appendix A.   
       
       
     4.3.3. subTemplateMultiList 

      A subTemplateMultiList specifies a generic Information Element 
      with a subTemplateMultiList abstract data type as defined in 
      Section 4.1.3. and list semantics as defined in Section 4.2.1.  
       
      EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this 
      new Information Element identifier, the value ZZZ is used in all 
      the examples and in the XML in Appendix A. 
       

      
      
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     4.4. New Structured Data Type Semantics 

     Structured data type semantics are provided in order to express 
     the relationship among multiple list elements in a Structured Data 
     Information Element.  These structured data type semantics require 
     a new IPFIX subregistry, as specified in the "IANA Considerations" 
     section.  The semantics are specified in the next following 
     subsections. 
      

     4.4.1. undefined 

     The "undefined" structured data type semantic specifies that the 
     semantic of list elements is not specified, and that, if a 
     semantic exists, then it is up to the Collecting Process to draw 
     its own conclusions.  The "undefined" structured data type 
     semantic, which is the default value, is used when none other 
     structured data type semantic applies.  

     For example, a mediator that wants to translate IPFIX [RFC5101] 
     into the export of structured data according to the specifications 
     in this document, doesn't know what the semantic is; it can only 
     guess, as the IPFIX specifications [RFC5101] does not contain any 
     semantic. Therefore, the mediator should use the "undefined" 
     semantic. 
      

     4.4.2. noneOf 

     The "noneOf" structured data type semantic specifies that none of 
     the elements are actual properties of the Data Record.   

     For example, a mediator might want to report to a Collector that a 
     specific Flow is suspicious, but that it checked already that this 
     Flow does not belong to the attack type 1, attack type 2, and 
     attack type 3.  So this Flow might need some further inspection.  
     In such a case, the mediator would report the Flow Record with a 
     basicList composed of (attack type 1, attack type 2, attack type 
     3) and the respective structured data type semantic of "noneOf". 

     Another example is a router that monitors some specific BGP AS-
     PATHs and reports if a Flow belongs to any of them.  If the router 
     wants to export that a Flow does not belong to any of the 
     monitored BGP AS-PATHs, the router reports a Data Record with a 
     basicList composed of (BGP AS-PATH 1, BGP AS-PATH 2, BGP AS-PATH 
     3) and the respective structured data type semantic of "noneOf". 
      
      
      
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     4.4.3. exactlyOneOf 

     The "exactlyOneOf" structured data type semantic specifies that 
     only a single element from the structured data is an actual 
     property of the Data Record.  This is equivalent to a logical XOR 
     operation. 

     For example, if a Flow record contains a basicList of outgoing 
     interfaces with the "exactlyOneOf" semantic, then it implies that 
     the reported Flow only egressed from a single interface, although 
     the Flow Record lists all of the possible outgoing interfaces. 
     This is a typical example of a per destination load-balancing. 

     Another example is a mediator that must aggregate Data Records 
     from different Observation Points and report an aggregated 
     Observation Point.  However, the different Observation Points can 
     be specified by different Information Element types depending on 
     the Exporter. For example: 

         Exporter1 Observation Point is characterized by the 
     exporterIPv4Address, so a specific Exporter can be represented. 

         Exporter2 Observation Point is characterized by the 
     exporterIPv4Address and a basicList of ingressInterface, so the 
     Exporting Process can express that the observations were made on a 
     series of input interfaces. 

         Exporter3 Observation Point is characterized by the 
     exporterIPv4Address and a specific lineCardId, so the Exporting 
     Process can express that the observation was made on a specific 
     line card. 

     If the mediator models the three different types of Observation 
     Points with the three Template Records below: 

      
         Template Record 1: exporterIPv4Address     
         Template Record 2: exporterIPv4Address, basicList of  
                            ingressInterface 
         Template Record 3: exporterIPv4Address, lineCardId 

     then it can represent the aggregated Observation Point with a 
     subTemplateMultiList and the semantic "exactlyOneOf". The  
     aggregated Observation Point is modeled with the Data Records 
     corresponding to either Template Record 1, Template Record 2, or 
     Template Record 3 but not more than one of these. This implies 
     that the Flow was observed at exactly one of the Observation 
      
      
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     Points reported. 
      

     4.4.4. oneOrMoreOf 

     The "oneOrMoreOf" structured data type semantic specifies that one 
     or more elements from the list in the structured data are actual 
     properties of the Data Record.  This is equivalent to a logical OR 
     operation.  

     Consider an example where a mediator must report an aggregated 
     Flow (e.g. by aggregating IP addresses from IP prefixes), with an 
     aggregated Observation Point. However, the different Observation 
     Points can be specified by different Information Element types as 
     described in Section 4.4.2. 

     If the mediator models the three different types of Observation 
     Points with the three Template Records below: 

         Template Record 1: exporterIPv4Address     
         Template Record 2: exporterIPv4Address, basicList of  
                            ingressInterface 
         Template Record 3: exporterIPv4Address, lineCardId 

     then it can represent the aggregated Observation Point with a 
     subTemplateMultiList and the semantic "oneOrMoreOf". The 
     aggregated Observation Point is modeled with the Data Records 
     corresponding to either Template Record 1, Template Record 2, or 
     Template Record 3. This implies that the Flow was observed on at 
     least one of the Observation Points reported, and potentially on 
     multiple Observation Points. 

      

     4.4.5. allOf 

     The "allOf" structured data type semantic specifies that all of 
     the list elements from the structured data are actual properties 
     of the Data Record. 

     For example, if a Record contains a basicList of outgoing 
     interfaces with the "allOf" semantic, then the observed Flow is 
     typically a multicast Flow where each packet in the Flow has been 
     replicated to each outgoing interface in the basicList. 
      

      
      
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     4.4.6. ordered 

     The "ordered" structured data type semantic specifies that 
     elements from the list in the structured data are ordered. 

     For example, an Exporter might want to export the AS10 AS20 AS30 
     AS40 BGP AS-PATH.  In such a case, the Exporter would report a 
     basicList composed of (AS10, AS20, AS30, AS40) and the respective 
     structured data type semantic of "ordered". 

      
     4.5. Encoding of IPFIX Data Types 

      The following subsections define the encoding of the abstract data 
      types defined in Section 4.1. above. These data types may be 
      encoded using either fixed or variable-length Information 
      Elements, as discussed in Section 5.1. .  Like in the IPFIX 
      specifications [RFC5101], all length are specified in octets. 
      
       
     4.5.1. basicList 

      The basicList Information Element defined in Section 4.3.1.  
      represents a list of zero or more instances of an Information 
      Element and is encoded 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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |   Semantic    |0|          Field ID           |   Element...  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...Length     |           basicList Content ...               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                    
                          Figure A: basicList Encoding  
       
       
      Semantic 
       
         The Semantic field indicates the relationship among the 
         different Information Element values within this Structured 
         Data Information Element. Refer to IANA's IPFIX "structured 
         data types semantics registry. 
      
      
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      Field ID 
       
          Field ID is the Information Element identifier of the 
          Information Element(s) contained in the list. 
           
           
      Element Length 
       
          Per Section 7 of [RFC5101], the Element Length field indicates 
          the length, in octets, of each list element specified by Field 
          ID, or contains the value 0xFFFF if the length is encoded as a 
          variable-length Information Element at the start of the 
          basicList Content. 
           
          The Element Length field is effectively part of the header, so 
          even in the case of a zero-element list, it MUST NOT be 
          omitted. 
           
           
      basicList Content 
       
          A Collecting Process decodes list elements from the basicList 
          Content until no further data remains.  A field count is not 
          included but can be derived when the Information Element is 
          decoded. 
           
      Note that in the diagram above, Field ID is shown with the 
      Enterprise bit (most significant bit) set to 0.  If instead the 
      Enterprise bit is set to 1, a four-byte Enterprise Number MUST be 
      encoded immediately after the Element Length as shown below.  See 
      the "Field Specifier Format" section in the IPFIX Protocol 
      [RFC5101] for additional information. 
       
       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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |    Semantic   |1|         Field ID            |   Element...  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...Length     |               Enterprise Number ...           | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |              basicList Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   
       
       
      
      
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              Figure B: basicList Encoding with Enterprise Number 
       

      Also note that, if a basicList has zero elements, the encoded data 
      contains the Semantic field, Field ID, the Element Length field 
      and the four-byte Enterprise Number (if present), while basicList 
      Content is empty. 

      If the basicList is encoded as a variable-length Information 
      Element in less than 255 octets, it MAY be encoded with the Length 
      field per Section 7 of [RFC5101] as shown in Figure C.  However, 
      the three-byte length encoding, as shown Figure D, is RECOMMENDED 
      (see section 5.1. ). 
      
       
       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)|   Semantic    |0|          Field ID           | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         Element Length        | basicList Content ...         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
                                        
           Figure C: Variable-Length basicList Encoding (Length < 255 
                                    octets) 
       
       
      If the basicList is encoded as a variable-length Information 
      Element in 255 or more octets, it MUST be encoded with the Length 
      field per Section 7 of [RFC5101] 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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |      Length (0 to 65535)      |   Semantic    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|          Field ID           |        Element Length         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                      basicList Content ...                    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      
      
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      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       

        Figure D: Variable-Length basicList Encoding (Length 0 to 65535 
                                    octets) 
         
         
     4.5.2. subTemplateList 

      The subTemplateList Information Element represents a list of zero 
      or more Data Records corresponding to a specific Template.  
      Because the Template Record referenced by a subTemplateList 
      Information Element can itself contain other subTemplateList 
      Information Elements, and because these Template Record references 
      are part of the Information Elements content in the Data Record, 
      it is possible to represent complex hierarchical data structures.  
      The following diagram shows how a subTemplateList Information 
      Element is encoded within a Data Record: 
       
       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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |   Semantic    |         Template ID           |     ...       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                subTemplateList Content    ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
                       Figure E: subTemplateList Encoding 
       
       
      Semantic 
      
          The Semantic field indicates the relationship among the 
          different Data Records within this Structured Data Information 
          Element. 
       
      Template ID 
       
          The Template ID field contains the ID of the template used to 
          encode and decode the subTemplateList Content. 
           
      subTemplateList Content 
      
      
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          subTemplateList Content consists of zero or more instances of 
          Data Records corresponding to the Template ID specified in the 
          Template ID Field.  A Collecting Process decodes the 
          subTemplateList Content until no further data remains.  A 
          record count is not included but can be derived when the 
          subTemplateList is decoded.  Encoding and decoding are 
          performed recursively if the specified Template itself 
          contains Structured Data Information Elements as described 
          here. 
       
      Note that, if a subTemplateList has zero elements, the encoded 
      data contains only the Semantic field and the Template ID field, 
      while subTemplateList Content is empty. 
      
      If the subTemplateList is encoded as a variable-length Information 
      Element in less than 255 octets, it MAY be encoded with the Length 
      field per Section 7 of [RFC5101] as shown in Figure F.  However, 
      the three-byte length encoding, as shown Figure G, is RECOMMENDED 
      (see section 5.1. ). 
      
       
       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)|   Semantic    |         Template ID           | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                subTemplateList Content    ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
                                        
        Figure F: Variable-Length subTemplateList Encoding (Length < 255 
                                    octets) 
       
      If the subTemplateList is encoded as a variable-length Information 
      Element in 255 or more octets, it MUST be encoded with the Length 
      field per Section 7 of [RFC5101] 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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |      Length (0 to 65535)      |   Semantic    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         Template ID           | subTemplateList Content ...   | 
      
      
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       

        Figure G: Variable-Length subTemplateList Encoding (Length 0 to 
                                 65535 octets) 
      

     4.5.3. subTemplateMultiList 

      Whereas each element in a subTemplateList Information Element 
      corresponds to a single Template, it is sometimes useful for a 
      list to contain elements corresponding to different Templates.  To 
      support this case, each top-level element in a 
      subTemplateMultiList Information Element carries a Template ID, 
      Length and zero or more Data Records corresponding to the Template 
      ID.  The following diagram shows how a subTemplateMultiList 
      Information Element is encoded within a Data Record.  Note that 
      the encoding following the Semantic field is consistent with the 
      Set Header specified in [RFC5101]. 
       
       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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |    Semantic   |         Template ID X         |Data Records...| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ... Length X  |        Data Record X.1 Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |        Data Record X.2 Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |        Data Record X.L Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |         Template ID Y         |Data Records...|  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ... Length Y  |        Data Record  Y.1 Content ...           | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |        Data Record Y.2 Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      
      
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      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |        Data Record Y.M Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |         Template ID Z         |Data Records...| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ... Length Z  |        Data Record Z.1 Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |        Data Record Z.2 Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |        Data Record Z.N Content ...            | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      ...      |    
      +-+-+-+-+-+-+-+-+   
       
                   Figure H: subTemplateMultiList Encoding 
                                        
      Semantic 
       
          The Semantic field indicates the top-level relationship among 
          the series of Data Records corresponding to the different 
          Template Records within this Structured Data Information 
          Element. 
           
           
      Template ID 
       
          Unlike the subTemplateList Information Element, each element 
          of the subTemplateMultiList contains a Template ID which 
          specifies the encoding of the following Data Records. 
           
      Data Records Length 
        
          The total length of the Data Records encoding for the Template 
          ID previously specified, including the 2 bytes for the 
          Template ID and the 2 bytes for the Data Records Length field 
          itself. 
          
      Data Record X.M  
      
      
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          The Data Record X.M consists of the Mth Data Record of the 
          Template Record X.  A Collecting Process decodes the Data 
          Records according to Template Record X until no further data 
          remains, according to the Data Records Length X. Further 
          Template IDs and Data Records may then be decoded according to 
          the overall subTemplateMultiList length.  A record count is 
          not included but can be derived when the Element Content is 
          decoded.  Encoding and decoding are performed recursively if 
          the specified Template itself contains Structured Data 
          Information Elements as described here. 
           
       
      In the exceptional case of zero instances in the 
      subTemplateMultiList, no data is encoded, only the Semantic field 
      and Template ID field(s), and the Data Record Length field is set 
      to zero. 
       
      If the subTemplateMultiList is encoded as a variable-length 
      Information Element in less than 255 octets, it MAY be encoded 
      with the Length field per Section 7 of [RFC5101] as shown in 
      Figure I.  However, the three-byte length encoding, as shown 
      Figure J, is RECOMMENDED (see section 5.1. ). 
       
       
       
       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)|    Semantic   |         Template ID X         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      Data Records Length X    |  Data Record X.1 Content ...  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |   Data Record X.2 Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |   Data Record X.L Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |         Template ID Y         |       
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |    Data RecordsLength Y       |   Data Record Y.1 Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      
      
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      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |   Data Record Y.2 Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |   Data Record Y.M Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |         Template ID Z         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      Data Records Length Z    |   Data Record Z.1 Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |   Data Record Z.2 Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |   Data Record Z.N Content ... | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             ...               |    
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   
       
                                        
      Figure I: Variable-Length subTemplateMultiList Encoding (Length < 
                                 255 octets) 
       
       
      If the subTemplateMultiList is encoded as a variable-length 
      Information Element in 255 or more octets, it MUST be encoded with 
      the Length field per Section 7 of [RFC5101] 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 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |      Length (0 to 65535)      |   Semantic    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         Template ID X         |    Data Records Length X      |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Data Record X.1 Content ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      
      
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Data Record X.2 Content ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Data Record X.L Content ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         Template ID Y         |    Data Records Length Y      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Data Record  Y.1 Content ...                | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Data Record Y.2 Content ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   Data Record Y.M Content ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |         Template ID Z         |    Data Records Length Z      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                     Data Record Z.1 Content ...               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                     Data Record Z.2 Content ...               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                     Data Record Z.N Content ...               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       

        Figure J: Variable-Length subTemplateMultiList Encoding (Length 
                               0 to 65535 octets) 
       
       
     5. Structured Data Format 

       

      
      
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     5.1. Length Encoding Considerations 

      The new Structured Data Information Elements represent a list that 
      potentially carries complex hierarchical and repeated data.   
       
      When the encoding of a Structured Data Information Element has a 
      fixed length (because, for example, it contains the same number of 
      fixed-length elements, or if the permutations of elements in the 
      list always produces the same total length), the element length 
      can be encoded in the corresponding Template Record. 
       
      However, when representing variable-length data, hierarchical 
      data, and repeated data with variable element counts, where the 
      number and length of elements can vary from record to record, we 
      RECOMMEND that the Information Elements are encoded using the 
      variable-length encoding described in Section 7 of [RFC5101], with 
      the length carried before the Structured Data Information Element 
      encoding. 
       
      Because of the complex and repeated nature of the data, it is 
      potentially difficult for the Exporting Process to efficiently 
      know in advance the exact encoding size.  In this case, the 
      Exporting Process may encode the available data starting at a 
      fixed offset and fill in the final length afterwards.  Therefore, 
      the three-byte length encoding is RECOMMENDED for variable-length 
      information elements in all Template Records containing a 
      Structured Data Information Element, even if the encoded length 
      can be less than 255 bytes, because the starting offset of the 
      data is known in advance. 
                                              
      When encoding such data, an Exporting Process MUST take care to 
      not exceed the maximum allowed IPFIX message length of 65535 bytes 
      as specified in [RFC5101].  
       
       
       
     5.2. Recursive Structured Data 

      It is possible to define recursive relationships between IPFIX 
      structured data instances, for example when representing a tree 
      structure.  The simplest case of this might be a basicList where 
      each element is itself a basicList, or a subTemplateList where one 
      of the fields of the referenced template is itself a 
      subTemplateList referencing the same Template.  Also, the 
      Exporting Process MUST take care when encoding recursively-defined 
      structured data, not to exceed the maximum allowed length of an 
      IPFIX Message (as noted in Length Encoding Considerations). 
      
      
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     5.3. Structured Data Information Elements Applicability in Options 
        Template Sets 

      Structured Data Information Elements MAY be used in Options 
      Template Sets. 
       
      As an example, consider a mediation function that must aggregate 
      Data Records from multiple Observation Point types:  
       
         Router 1, (interface 1)  
         Router 2, (line card A)  
         Router 3, (line card B)  
         Router 4, (line card C, interface 2)  
       
      In order to encode the PSAMP Selection Sequence Report 
      Interpretation [RFC5476], the mediation function must express this 
      combination of Observation Points as a single new Observation 
      Point.  Recall from [RFC5476] that the PSAMP Selection Sequence 
      Report Interpretation consists of the following fields:  
       
        Scope:     selectionSequenceId  
        Non-Scope: one Information Element mapping the Observation Point  
                   selectorId (one or more)  
       
      Without structured data, there is clearly no way to express the 
      complex aggregated Observation Point as "one Information Element 
      mapping the Observation Point".  However, the desired result may 
      be easily achieved using the structured data types.  Refer to 
      Section 9.5. for an encoding example related to this case study. 
       
      Regarding the scope in the Options Template Record, the IPFIX 
      specification [RFC5101] mentions that "The IPFIX protocol doesn't 
      prevent the use of any Information Elements for scope".  
      Therefore, a Structured Data Information Element MAY be used as 
      scope in an Options Template Set.   
       
      Extending the previous example, the mediation function could 
      export a given name for this complex aggregated Observation Point:  
       
         Scope: Aggregated Observation Point (structured data)  
         Non-Scope: a new Information Element containing the name   
       
       

      
      
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     5.4. Usage Guidelines for Equivalent Data Representations 

      Because basicList, subTemplateList, and subTemplateMultiList are 
      all lists, in several cases there is more than one way to 
      represent what is effectively the same data structure.  However, 
      in some cases, one approach has an advantage over the other e.g. 
      more compact, uses fewer resources, etc., and is therefore 
      preferred over an alternate representation. 

      A subTemplateList can represent the same simple list of single-
      value Information Elements as a basicList, if the Template 
      referenced by the subTemplateList contains only one single-valued 
      Information Element.  Although the encoding is more compact than a 
      basicList by two bytes, using a subTemplateList in this case 
      requires a new Template per Information Element.  The basicList 
      requires no additional Template and is therefore RECOMMENDED in 
      this case.  

      Although a subTemplateMultiList with one Element can represent the 
      contents of a subTemplateList, the subTemplateMultiList carries 
      two additional bytes (Element Length).  It is also potentially 
      useful to a Collecting Process to know in advance that a 
      subTemplateList directly indicates that list element types are 
      consistent.  The subTemplateList Information Element is therefore 
      RECOMMENDED in this case. 

      The Semantic field in a subTemplateMultiList indicates the top-
      level relationship among the series of Data Records corresponding 
      to the different Template Records, within this Structured Data 
      Information Element.  If a semantic is required to describe the 
      relationship among the different Data Records corresponding to a 
      single Template ID within the subTemplateMultiList, then an 
      encoding based on a basicList of subTemplateLists should be used, 
      refer to Section 5.6 for more information.  Alternatively, if a 
      semantic is required to describe the relationship among all Data 
      Records within a subTemplateMultiList (regardless of the Template 
      Record), an encoding based on a subTemplateMultiList with one Data 
      Record corresponding to a single Template ID can be used.  

      Note that the referenced Information Element(s) in the Structured 
      Data Information Elements can be taken from the IPFIX information 
      model [RFC5102], the PSAMP information model [RFC5477], any of the 
      Information Elements defined in the IANA IPFIX registry [IANA-
      IPFIX] or enterprise-specific Information Elements. 
        
      If a Template Record contains a subTemplateList as the only field, 
      a Set encoding as specified in the IPFIX protocol specifications 
      
      
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      [RFC5101] should be considered, unless: 
       - A relationship among multiple list elements must be exported, 
      in which case, the semantic from the IPFIX Structured Data 
      Information Element can convey this relationship. 
       - The Exporting Process wants to convey the number of elements in 
      the list, even in the special cases of zero or one element in the 
      list. Indeed, the case of an empty list cannot be represented with 
      the IPFIX protocol specifications [RFC5101].  In the case of a 
      single element list, the Template Record specified in the IPFIX 
      protocol specification [RFC5101] could be used.  However, on the 
      top of the Template Record with the subTemplateList to export 
      multiple list elements, this supplementary Template would impose 
      some extra management, both on the Exporting Process and on the 
      Collecting Process, which might have to correlate the information 
      from two Template Records. 
       
      Similarly, if a Template Record contains a subTemplateMultiList as 
      the only field, an IPFIX Message as described in the IPFIX 
      protocol specification [RFC5101] should be considered, unless: 
      - A relationship among top-level list elements must be exported, 
      in which case, the semantic from the IPFIX Structured Data 
      Information Element can convey this relationship. 
      - The Exporting Process wants to convey the number of Data Records 
      corresponding to every Template in the subTemplateMultiList. 
       
       
     5.5. Padding 

      The Exporting Process MAY insert some padding octets in structured 
      data field values in a Data Record by including the 
      'paddingOctets' Information Element as described in [RFC5101] 
      Section 3.3.1.  The paddingOctets Information Element can be 
      included in a Template Record referenced by structured data 
      Information Element for this purpose. 
       
                            
     5.6. Semantic  

     Semantic interpretations of received Data Records at or beyond the 
     Collecting Process remain explicitly undefined, unless that data 
     is transmitted using this extension with explicit Structured Data 
     type semantic information. 

     It is not the Exporter's role to check the validity of the 
     semantic representation of Data Records.   

      
      
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     More complex semantics can be expressed as a combination of the  
     Semantic Data Information Elements specified in this document. 

     For example, the export of the AS10 AS20 AS30 AS40 {AS50,AS60} BGP 
     AS-PATH would be reported as a basicList of two elements, each 
     element being a basicList of BGP AS, with the top level structured 
     data type semantic of "ordered".  The first element would contain 
     a basicList composed of (AS10,AS20,AS30,AS40) and the respective 
     structured data type semantic of "ordered", while the second 
     element would contain a basicList composed of (AS50, AS60) and the 
     respective structured data type semantic of "exactlyOneOf".  A 
     high level Data Record diagram would be represented as:  

          BGP AS-PATH = (basicList, ordered,  

              (basicList, ordered, AS10,AS20,AS30,AS40),  

              (basicList, exactlyOneOf, AS50, AS60) 

          )  

     If a semantic is required to describe the relationship among the 
     different Data Records corresponding to a single Template ID 
     within the subTemplateMultiList, then an encoding based on a 
     basicList of subTemplateLists should be used, as shown in the next 
     case study. 
      
      Case study 1:  

     In this example, an Exporter monitoring security attacks must 
     export a list of security events consisting of attackers and 
     targets.  For the sake of the example, assume that the Collector 
     can differentiate the attacker (which is expressed using source 
     fields) from the target (which is expressed using destination 
     fields).  Imagine that attackers A1 or A2 may attack targets T1 
     and T2. 

     The first case uses a subTemplateMultiList composed of two 
     Template Records, one representing the attacker and one 
     representing the target, each of them containing an IP address and 
     a port.   

          Attacker Template Record = (src IP address, src port) 

          Target Template Record = (dst IP address, dst port) 

     A high level Data Record diagram would be represented as:  
      
      
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           Alert = (subTemplateMultiList, allOf,  

              (Attacker Template Record, A1, A2), 

              (Target Template Record, T1, T2) 

           ) 

     The Collecting Process can only conclude that the list of 
     attackers (A1, A2) and the list of targets (T1, T2) are present, 
     without knowing the relationship amongst attackers and targets. 
     The Exporting Process would have to explicitly call out the 
     relationship amongst attackers and targets as the top level 
     semantic offered by the subTemplateMultiList isn't sufficient. 

     The only proper encoding for the previous semantic (i.e. attacker 
     A1 or A2 may attack target T1 and T2) uses a basicList of 
     subTemplateLists and is represented as follows:  

          Attacker Template Record = (src IP address, src port) 

          Target Template Record = (dst IP address, dst port) 

          Alert = (basicList, allof,  

                (subTemplateList, exactlyOneOf, attacker A1, A2) 

                (subTemplateList, allOf, target T1, T2) 

          )   

       

      Case study 2:  

     In this example, an Exporter monitoring security attacks must 
     export a list of attackers and targets.  For the sake of the 
     example, assume that the Collector can differentiate the attacker 
     (which is expressed using source fields) from the target (which is 
     expressed using destination fields).  Imagine that attackers A1 or 
     A2 are attacking target T1, while attacker A3 is attacking targets 
     T2 and T3.  The first case uses a subTemplateMultiList that 
     contains Data Records corresponding to two Template Records, one 
     representing the attacker and one representing the target, each of 
     them containing an IP address and a port. 

          Attacker Template Record = (src IP address, src port) 
      
      
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          Target Template Record = (dst IP address, dst port) 

     A high level Data Record diagram would be represented as:  

           Alert = (subTemplateMultiList, allOf,  

              (Attacker Template Record, A1, A2, A3), 

              (Target Template Record, T1, T2, T3) 

           ) 

     The Collecting Process can only conclude that the list of 
     attackers (A1, A2, A3) and the list of targets (T1, T2, T3) are 
     present, without knowing the relationship amongst attackers and 
     targets. 

     The second case could use a Data Record definition composed of the 
     following: 

           Alert = (subTemplateMultiList, allOf,  

              (Attacker Template Record, A1, A2), 

              (Target Template Record, T1), 

              (Attacker Template Record, A3), 

              (Target Template Record, T2, T3) 

           ) 

     With the above representation, the Collecting Process can infer 
     that the alert consists of the list of attackers (A1, A2), target 
     (T1), attacker (A3) and list of targets (T2, T3).   From the 
     sequence in which attackers and targets are encoded, the Collector 
     can possibly deduce that some relationship exists among (A1, A2, 
     T1) and (A2, T1, T2) but cannot understand what it is exactly.  
     So, there is a need for the Exporting Process to explicitly define 
     the relationship between the attackers and targets and the top-
     level semantic of the subTemplateMultiList is not sufficient. 

     The only proper encoding for the previous semantic (i.e. attacker 
     A1 or A2 attack target T1, attacker A3 attacks targets T2 and T3) 
     uses a basicList of subTemplateLists and is represented as 
     follows:  

      
      
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          Participant P1 = 

          (basicList, allOf,  

                (subTemplateList, exactlyOneOf, attacker A1, A2) 

                (subTemplateList, undefined, target T1) 

          ) 

          Participant P2 = 

          (basicList, allOf,  

                (subTemplateList, undefined, attacker A3, 

                (subTemplateList, allOf, targets T2, T3) 

          ) 

     The security alert is represented as a subTemplateList of 
     participants. 

          Alert = 

             (subTemplateList, allOf, Participant P1, Participant P2) 

     Note that, in the particular case of a single element in a 
     Structured Data Information Element, the semantic field is 
     actually not very useful since it specifies the relationship among 
     multiple elements.  Any choice of allOf, exactlyOneOr, or 
     OneOrMoreOf would provide the same result semantically.  
     Therefore, in case of a single element in a Structured Data 
     Information Element, the default "undefined" semantic SHOULD be 
     used. 
         
         
     6. Template Management  

      This section introduces some more specific Template management and 
      Template Withdrawal Message-related specifications compared to the 
      IPFIX protocol specification [RFC5101]. 
       
      First of all, the Template ID uniqueness is unchanged compared to 
      [RFC5101]; the uniqueness is local to the Transport Session and 
      Observation Domain that generated the Template ID.  In other 

      
      
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      words, the Set ID used to export the Template Record does not 
      influence the Template ID uniqueness. 
      
      While [RFC5101] mentions that: "If an Information Element is 
      required more than once in a Template, the different occurrences 
      of this Information Element SHOULD follow the logical order of 
      their treatments by the Metering Process.", this rule MAY be 
      ignored within Structured Data Information Elements.   
      
      As specified in [RFC5101], Templates that are not used anymore 
      SHOULD be deleted.  Deleting a Template implies that it MUST NOT 
      be used within subTemplateList and subTemplateMultiList any more.  
      Before reusing a Template ID, the Template MUST be deleted.  In 
      order to delete an allocated Template, the Template is withdrawn 
      through the use of a Template Withdrawal Message.   
      
      
     7. The Collecting Process's Side  

      This section introduces some more specific specifications to the 
      Collection Process compared to Section 9 in the IPFIX Protocol 
      [RFC5101].   
       
      As opposed to the IPFIX specification in [RFC5101], IPFIX Messages 
      with IPFIX Structured Data Information Elements change the IPFIX 
      concept from the Collector's point of view as the data types are 
      present in the Data Records rather than in the Template Records.  
      For example, a basicList Information Element in a Template Record 
      doesn't specify the list element data type, this information is 
      contained in the Data Record.  For example, in case of a 
      subTemplateMultiList, the Collecting Process must refer to the 
      included Template Records in the middle of the Data Record decode.  
      
      As described in [RFC5101], a Collecting Process MUST note the 
      Information Element identifier of any Information Element that it 
      does not understand and MAY discard that Information Element from 
      the Flow Record.  Therefore a Collection Process that does not 
      support the extension specified in this document can ignore the 
      Structured Data Information Elements in a Data Record, or it can 
      ignore Data Records containing these new Structured Data 
      Information Elements while continuing to process other Data 
      Records. 
       
     If the structured data contains the "undefined" structured data 
     type semantic, the Collecting Process MAY attempt to draw its own 
     conclusion in terms of the semantic contained in the Data Record.  

      
      
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     8. Defining New Information Elements Based on the New Abstract Data 
       Types 

     This document specifies three new abstract data types: basicList, 
     subTemplateList, and subTemplateMultiList.  As specified in 
     [RFC5102], the specification of new IPFIX Information Elements 
     uses the template specified in Section 2.1 of [RFC5102].  This 
     template mentioned existing and future the data types: "One of the 
     types listed in Section 3.1 of this document or in a future 
     extension of the information model."  So new Information Elements 
     can be specified based on the three new abstract data types.  
      
     The authors anticipate the creation of both enterprise-specific 
     and IANA Information Elements based on the IPFIX structured data 
     types. For example, bgpPathList, bgpSequenceList and bgpSetList, 
     of abstract types and semantics basicList/ordered, 
     basicList/ordered, and basicList/exactlyOneOf respectively would 
     define the complete semantic of the list. This specification 
     doesn't specify any new Information Elements beyond the ones in 
     Section 4.3. 
      
      
     9. Structured Data Encoding Examples 

      The following examples are created solely for the purpose of 
      illustrating how the extensions proposed in this document are 
      encoded. 

       

     9.1. Encoding a Multicast Data Record with basicList 

      Consider encoding a multicast Data Record containing the following 
     data: 

      --------------------------------------------------------------- 
       Ingress If | Source IP   | Destination IP  | Egress Interfaces 
      --------------------------------------------------------------- 
            9       192.0.2.201      233.252.0.1         1, 4, 8 
      --------------------------------------------------------------- 
       
      Template Record for the multicast Flows, with the Template ID 256: 

       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 = 2            |      Length = 24 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |       Template ID = 256       |       Field Count = 4         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|    ingressInterface = 10    |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|   sourceIPv4Address = 8     |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| DestinationIPv4Address = 12 |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|       basicList = XXX       |     Field Length = 0xFFFF     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
                 Figure K: Encoding basicList, Template Record 
       

      The list of outgoing interfaces is represented as a basicList with 
      semantic allOf, and the Length of the list is chosen to be encoded 
      in three bytes even though it may be less than 255 octets. 

      The Data Set is represented 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 = 256         |          Length = 36          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                     ingressInterface = 9                      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |               sourceIPv4Address = 192.0.2.201                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             DestinationIPv4Address = 233.252.0.1              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |        List Length = 17       | semantic=allOf| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | egressInterface FieldId = 14  |egressInterface Field Length=4 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                egressInterface value 1 = 1                    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                egressInterface value 2 = 4                    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                egressInterface value 3 = 8                    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
          

      
      
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           Figure L: Encoding basicList, Data Record, Semantic allOf 
      
        In the example above, the basicList contains fixed-length 
        elements.  To illustrate how variable-length elements would be 
        encoded, the same example is shown below with variable-length 
        interface names in the basicList instead: 

       
       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 = 44          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                     ingressInterface = 9                      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |               sourceIPv4Address = 192.0.2.201                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             DestinationIPv4Address = 233.252.0.1              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |        List Length = 25       | semantic=allOf| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| InterfaceName FieldId = 82  | InterfaceName Field Len=0xFFFF| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |  Length = 5   |      'F'      |      'E'      |      '0'      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     '/'       |      '0'      |  Length = 7   |      'F'      |              
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     'E'       |      '1'      |      '0'      |      '/'      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     '1'       |      '0'      |  Length = 5   |      'F'      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     'E'       |      '2'      |     '/'       |      '2'      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+            
       
       
       Figure M: Encoding basicList, Data Record with Variable-Length 
                          Elements, Semantic allOf  
      
                                         
     9.2. Encoding a Load-balanced Data Record with a basicList 

      Consider encoding a load-balanced Data Record containing the 
      following data: 

      --------------------------------------------------------------- 
       Ingress If | Source IP   | Destination IP  | Egress Interfaces 
      --------------------------------------------------------------- 
      
      
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            9       192.0.2.201      233.252.0.1         1, 4, 8 
      --------------------------------------------------------------- 
       

      So the Data Record egressed from either interface 1, 4, or 8.  The 
      Data Set is represented 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 = 256         |          Length = 36          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                     ingressInterface = 9                      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |               sourceIPv4Address = 192.0.2.201                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |             DestinationIPv4Address = 233.252.0.1              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |        List Length = 17       |sem=exactlyOne | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | egressInterface FieldId = 14  |egressInterface Field Length=4 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                egressInterface value 1 = 1                    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                egressInterface value 2 = 4                    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                egressInterface value 3 = 8                    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                       
        Figure N: Encoding basicList, Data Record, Semantic ExactlyOneOf 
                                         
                                         
     9.3. Encoding subTemplateList 

      As explained in Section 2.2. , multiple pairs of 
      (observationTimeMicroseconds, digestHashValue) must be collected 
      from two different Observation Points to passively compute the 
      one-way delay across the network.  This data can be exported with 
      an optimized Data Record that consists of the following 
      attributes:  
       
          5-tuple 
                    { observationTimeMicroseconds 1, digestHashValue 1 } 
                    { observationTimeMicroseconds 2, digestHashValue 2 } 
                    { observationTimeMicroseconds 3, digestHashValue 3 } 
                    { ...  , ... } 
      
      
      
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      A subTemplateList is best suited for exporting the list of 
      (observationTimeMicroseconds, digestHashValue).  For illustration 
      purposes, the number of elements in the list is 5; in practice, it 
      could be more. 
      
      ------------------------------------------------------------------ 
      srcIP     | dstIP      | src   | dst  |proto| one-way delay 
                |            | Port  | Port |     |   metrics 
      ------------------------------------------------------------------ 
      192.0.2.1  192.0.2.105   1025     80     6    Time1, 0x0x91230613   
                                                    Time2, 0x0x91230650   
                                                    Time3, 0x0x91230725   
                                                    Time4, 0x0x91230844   
                                                    Time5, 0x0x91230978 
      ------------------------------------------------------------------ 
      
      The following Template is defined for exporting the one-way delay 
      metrics: 
      
      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 = 16 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |       Template ID = 257       |       Field Count = 2         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| observationTimeMicroSec=324 |       Field Length = 8        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|   digestHashValue = 326     |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
         Figure O: Encoding subTemplateList, Template for One-Way Delay 
                                    Metrics 
      
       
      The Template Record for the Optimized Data Record 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 = 2            |      Length = 32 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |       Template ID = 258       |       Field Count = 6         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|   sourceIPv4Address = 8     |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 

      
      
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      |0| destinationIPv4Address = 12 |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|  sourceTransportPort = 7    |       Field Length = 2        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| destinationTransportPort= 11|       Field Length = 2        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| protocolIdentifier = 4      |       Field Length = 1        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|  subTemplateList = YYY      |     Field Length = 0xFFFF     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                         
              Figure P: Encoding subTemplateList, Template Record 
      
     The list of (observationTimeMicroseconds, digestHashValue) is 
     exported as a subTemplateList with semantic allOf.  The Length of 
     the subTemplatelist is chosen to be encoded in three bytes even 
     though it may be less than 255 octets. 
      
     The Data Record is represented 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 = 258          |      Length = 83 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                sourceIPv4Address = 192.0.2.1                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |              destinationIPV4Address = 192.0.2.105             | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | sourceTransportPort = 1025    | destinationTransportPort = 80 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | Protocol = 6  |      255      | one-way metrics list len = 63 |  
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | semantic=allOf|       TemplateID = 257        | TimeValue1    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                 ... octets 2-5 of TimeValue1                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          ... octets 6-8 of TimeValue1         |digestHashVal1=| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                ... 0x0x91230613               | TimeValue2    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                 ... octets 2-5 of TimeValue2                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          ... octets 6-8 of TimeValue2         |digestHashVal2=| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                ... 0x0x91230650               | TimeValue3    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      
      
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      |                 ... octets 2-5 of TimeValue3                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          ... octets 6-8 of TimeValue3         |digestHashVal3=| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                ... 0x0x91230725               | TimeValue4    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                 ... octets 2-5 of TimeValue4                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          ... octets 6-8 of TimeValue4         |digestHashVal4=| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                ... 0x0x91230844               | TimeValue5    | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                 ... octets 2-5 of TimeValue5                  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          ... octets 6-8 of TimeValue5         |digestHashVal5=| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                ... 0x0x91230978               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
               
      
                   Figure Q: Encoding subTemplateList, Data Set 
           
         
     9.4. Encoding subTemplateMultiList  

     As explained in Section 4.5.3., a subTemplateMultiList is used to 
     export a list of mixed-type content where each top level element 
     corresponds to a different Template Record.   

     To illustrate this, consider the Data Record with the following 
     attributes: 

       
          5-tuple (Flow Keys), octetCount, packetCount 
                    attributes for filtering 
                         selectorId,  
                         selectorAlgorithm 
                    attributes for sampling 
                         selectorId,  
                         selectorAlgorithm,  
                         samplingPacketInterval,  
                         samplingPacketSpace 
         
     This example demonstrates that the Selector Report Interpretation 
     [RFC5476] can be encoded with the subTemplateMultiList.  More 
     specifically, the example describes Property Match Filtering 
     Selector Report Interpretation [RFC5476] used for filtering 
      
      
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     purposes, and the Systemic Count-Based Sampling as described in 
     Section 6.5.2.1 of [RFC5476].  Some traffic will be filtered 
     according to match properties configured, some will be sampled, 
     some will be filtered and sampled, and some will not be filtered or 
     be sampled. 
      
     A subTemplateMultiList is best suited for exporting this variable 
     data.  A Template is defined for filtering attributes and another 
     Template is defined for sampling attributes.  A Data Record can 
     contain data corresponding to either of the Templates, both of 
     them, or neither of them.  

      
     Consider the example below where the following Data Record contains 
     both filtering and sampling attributes. 

     Key attributes of the Data Record: 

      ------------------------------------------------------------------ 
      srcIP      | dstIP     | src  | dst  | proto | octetCount | packet  
                 |           | Port | Port |       |            | Count 
      ------------------------------------------------------------------ 
      2001:DB8::1 2001:DB8::2  1025    80      6       108000      120 
      ------------------------------------------------------------------ 
      

     Filtering attributes: 

      ------------------------------------------- 
      selectorId  | selectorAlgorithm 
      ------------------------------------------- 
         100         5 (Property Match Filtering)      
      ------------------------------------------- 
      

     Sampling attributes: 

     For Systemic Count-Based Sampling as defined in Section 6.5.2.1 of 
     [RFC5476] the required algorithm-specific Information Elements are: 

           samplingPacketInterval: number of packets selected in a row 
           samplingPacketSpace:    number of packets between selections 
      
        Example of a simple 1 out-of 100 systematic count-based Selector 
        definition, where the samplingPacketInterval is 1 and the 
        samplingPacketSpace is 99. 
      
      
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      -------------------------------------------------------------- 
      selectorId | selectorAlgorithm        | sampling | sampling 
                 |                          | Packet   | Packet 
                 |                          | Interval | Space 
      -------------------------------------------------------------- 
         15        1 (Count-Based Sampling)      1         99 
      -------------------------------------------------------------- 
      

     To represent the Data Record, the following Template Records are 
     defined: 

         Template for filtering attributes: 259 
          Template for sampling attributes: 260 
          Template for Flow Record: 261 
                                         
          Flow record (261) 
              |  (sourceIPv6Address) 
              |  (destinationIPv6Address) 
              |  (sourceTransportPort) 
              |  (destinationTransportPort) 
              |  (protocolIdentifier) 
              |  (octetTotalCount) 
              |  (packetTotalCount) 
              | 
              +------ filtering attributes (259) 
              |          (selectorId) 
              |          (selectorAlgorithm) 
              | 
              +------ sampling attributes (260) 
              |          (selectorId) 
              |          (selectorAlgorithm) 
              |          (samplingPacketInterval) 
              |          (samplingPacketSpace) 
                
       
      The following Template Record is defined for filtering attributes: 
        
       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 = 16          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      Template ID = 259        |        Field Count = 2        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|    selectorId = 302         |        Field Length = 4       | 
      
      
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| selectorAlgorithm = 304     |        Field Length = 1       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                        
       Figure R: Encoding subTemplateMultiList, Template for Filtering 
                                  Attributes 
       
      The Template for sampling attributes is defined 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 = 2           |          Length = 24          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      Template ID = 260        |        Field Count = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|    selectorId = 302         |        Field Length = 4       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|  selectorAlgorithm = 304    |        Field Length = 1       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| samplingPacketInteval = 305 |        Field Length = 1       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| samplingPacketSpace = 306   |        Field Length = 1       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                        
        Figure S: Encoding subTemplateMultiList, Template for Sampling 
                                  Attributes 
         

        Note that while selectorAlgorithm is defined as unsigned16, and 
        samplingPacketInterval and samplingPacketSpace are defined as 
        unsigned32, they are compressed down to 1 octet here as allowed 
        by Reduced Size Encoding in Section 6.2 of the IPFIX protocol 
        specifications [RFC5101]. 

         
      Template for the Flow Record is defined as shown below: 
       
       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 = 40          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      Template ID = 261        |        Field Count = 8        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|   sourceIPv6Address = 27    |       Field Length = 16       | 
      
      
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| destinationIPv6Address = 28 |       Field Length = 16       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| sourceTransportPort = 7     |       Field Length = 2        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| destinationTransportPort=11 |       Field Length = 2        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| protocolIdentifier = 4      |       Field Length = 1        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|   octetTotalCount = 85      |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|   packetTotalCount = 86     |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| subTemplateMultiList = ZZZ  |     Field Length = 0XFFFF     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                        
      Figure T: Encoding subTemplateMultiList, Template for Flow Record 
       
     A subTemplateMultiList with semantic allOf is used to export the 
     filtering and sampling attributes.  The Length field of the 
     subTemplateMultilist is chosen to be encoded in three bytes even 
     though it may be less than 255 octets. 
      
     The Data Record is encoded 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 = 261            |          Length = 73          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                      sourceIPv6Address =        ...           | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                          2001:DB8::1                          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                   destinationIPv6Address =      ...           | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                              ...                              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |                          2001:DB8::2                          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |  sourceTransportPort = 1025   | destinationTransportPort = 80 | 
      
      
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | protocol = 6  |        octetTotalCount = 108000               | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     ...       |        packetTotalCount = 120                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |     ...       |      255      | Attributes List Length = 21   | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |semantic=allOf | Filtering Template ID = 259   |Filtering Attr | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...Length = 9 |              selectorId = ...                 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...  100      |selectorAlg = 5|  Sampling Template ID = 260   | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | Sampling Attributes Length=11 |         selectorId = ...      | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |  ...         15               |selectorAlg = 1|  Interval = 1 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | Space = 99    | 
      +-+-+-+-+-+-+-+-+   
       
              Figure U: Encoding subTemplateMultiList, Data Set 
      
         
     9.5. Encoding an Options Template Set using Structured Data 

      As described in Section 5.3. , consider a mediation function that 
      must aggregate Data Records from different Observation Points. 
       
      Say Observation Point 1 consists of one or more interfaces, 
      Observation Points 2 and 3 consist of one or more line cards, and 
      Observation Point 4 consists of one or more interfaces and one or 
      more line cards.  Without structured data, a template would have 
      to be defined for every possible combination to interpret the data 
      corresponding to each of the Observation Points.  However, with 
      structured data, a basicList can be used to encode the list of 
      interfaces and another basicList can be used to encode the list of 
      line cards.  
       
      For the sake of simplicity, each Observation Point shown below has 
      the IP address corresponding to the Router and an <interface> or 
      <linecard> or <line card and interface>.  This can very well be 
      extended to include a list of interfaces and a list of linecards 
      using basicLists as explained above.  
       
         Observation Point 1: Router 1, (interface 1)  
         Observation Point 2: Router 2, (line card A)   

      
      
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         Observation Point 3: Router 3, (line card B)   
         Observation Point 4: Router 4, (line card C, interface 2)  
       
       
      The mediation function wishes to express this as a single 
      Observation Point, in order to encode the PSAMP Selection 
      Sequence Report Interpretation (SSRI).  Recall from [RFC5476] 
      that the PSAMP Selection Sequence Report Interpretation 
      consists of the following fields:  
       
        Scope:     selectionSequenceId  
        Non-Scope: one Information Element mapping the  
                   Observation Point  
                   selectorId (one or more)  
       
      For example, the Observation Point detailed above may be 
      encoded in a PSAMP Selection Sequence Report Interpretation as 
      shown below:  
       
       Selection Sequence 7 (Filter->Sampling):  
        Observation Point: subTemplateMultiList.  
         Router 1 (IP address = 192.0.2.11), (interface 1)  
         Router 2 (IP address = 192.0.2.12), (line card A)  
         Router 3 (IP address = 192.0.2.13), (line card B) 
         Router 4 (IP address = 192.0.2.14), (line card C, interface 2)  
         selectorId: 5 (Filter, match IPV4SourceAddress 192.0.2.1)  
         selectorId: 10 (Sampler, Random 1 out-of ten) 
       
      The following Templates are defined to represent the PSAMP SSRI: 
      Template for representing PSAMP SSRI: 262 
      Template for representing interface: 263 
      Template for representing linecard: 264 
      Template for representing linecard and interface: 265 
       
          
          PSAMP SSRI (262) 
              | (SelectionSequenceId) 
              | 
              +--- Observation Point 1 (263) 
              |      (exporterIPv4Address) 
              |      (Interface Id) 
              | 
              +--- Observation Point 2 and 3 (264) 
              |      (exporterIPv4Address) 
              |      (line card) 
      
      
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              | 
              +--- Observation Point 4 (265) 
              |      (exporterIPv4Address) 
              |      (line card) 
              |      (Interface Id) 
              | 
              | (selectorId 1) 
              | (selectorId 2) 
       
          
     Note that the example could further be improved with a basicList  
     of selectorId if many Selector IDs have to be reported. 
       
                                        
                      Figure V: PSAMP SSRI to be encoded 
       
        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 = 26          |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |        Template ID = 262      |         Field Count = 4       |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |     Scope Field Count =  1    |0|  selectionSequenceId = 301  |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |       Scope 1 Length = 4      |0| subTemplateMultiList =  ZZZ |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |     Field Length = 0xFFFF     |0|      selectorId = 302       |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |        Field Length = 4       |0|      selectorId = 302       |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |        Field Length = 4       |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                         
             Figure W: Options Template Record for PSAMP SSRI using 
                              subTemplateMultiList 
                                         
        
      A subTemplateMultiList with semantic allOf is used to encode the 
      list of Observation Points. 
       
        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 = 16          |  

      
      
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       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |        Template ID = 263      |         Field Count = 2       |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |0|   exporterIPv4Address = 8   |        Field Length = 4       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |0|   ingressInterface = 10     |        Field Length = 4       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                                        
             Figure X: PSAMP SSRI, Template Record for interface 
                                        
                                        
        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 = 16          |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |        Template ID = 264      |         Field Count = 2       |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |0|   exporterIPv4Address = 8   |         Field Length = 4      | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |0|      lineCardId = 141       |         Field Length = 4      | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
         
              Figure Y: PSAMP SSRI, Template Record for linecard  
                                        
                                        
        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 = 20          |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |        Template ID = 265      |         Field Count = 3       |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |0|   exporterIPv4Address = 8   |       Field Length = 4        | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |0|      lineCardId = 141       |        Field Length = 4       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |0|    ingressInterface = 10    |        Field Length = 4       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       
       Figure Z: PSAMP SSRI, Template Record for linecard and interface 
                                         
                                        
      The PSAMP SSRI Data Set is represented as follows: 
      
       

      
      
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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 = 262         |           Length = 68         |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |                    selectionSequenceId = 7                    |  
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
       |      255      | Observation Point List Len=49 |semantic=allOf | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |     OP1 Template ID = 263     |        OP1 Length = 12        | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |         Router 1 exporterIPv4Address = 192.0.2.11             | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                  OP1 ingressInterface = 1                     | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |   OP2&OP3 Template ID = 264   |    OP2 & OP3 Length = 20      | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |         Router 2 exporterIPv4Address = 192.0.2.12             | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                      OP2 lineCardId = A                       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |         Router 3 exporterIPv4Address = 192.0.2.13             | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                      OP3 lineCardId = B                       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |     OP4 Template ID = 265     |         OP4 Length = 16       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |         Router 4 exporterIPv4Address = 192.0.2.14             | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                      OP4 lineCardId = C                       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                   OP4 ingressInterface = 2                    | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                         selectorId = 5                        | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |                         selectorId = 10                       | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      
       Figure ZA: Example of a PSAMP SSRI Data Record, Encoded using a 
                             subTemplateMultiList 
         
      Note that the Data Record above contains multiple instances of 
      Template 264 to represent Observation Point 2 (Router2, line card 
      A) and Observation Point 3 (Router3, line card B).  Instead, if a 
      single Observation Point had both line card A and line card B, a 
      basicList would be used to represent the list of line cards. 
     
      
      
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     10. Relationship with the Other IFPIX Documents 

     10.1. Relationship with Reducing Redundancy  

        "Reducing Redundancy in IP Flow Information Export (IPFIX) and 
        Packet Sampling (PSAMP) Reports" [RFC5473] describes a bandwidth 
        saving method for exporting Flow or packet information using the 
        IP Flow Information eXport (IPFIX) protocol. 

        It defines the commonPropertiesID Information Element for 
        exporting Common Properties. 

      

     10.1.1. Encoding Structured Data Element using Common Properties. 

        When Structured Data Information Elements contain repeated 
        elements, these elements may be replaced with a 
        commonPropertiesID Information Element as specified in 
        [RFC5473].  The replaced elements may include the basicList, 
        subTemplateList and subTemplateMultiList Information Elements. 

        This technique might help reducing the bandwidth requirements 
        for the export.  However, a detailed analysis of the gain has 
        not been done; refer to Section 8.3 of [RFC5473] for further 
        considerations. 

         

     10.1.2. Encoding Common Properties elements With Structured Data 
        Information Element. 

        Structured Data Information Element MAY be used to define a list 
        of commonPropertiesID, as a replacement for the specifications 
        in [RFC5473]. 

        Indeed, the example in figures 1 and 2 of [RFC5473] can be 
        encoded with the specifications in this document.   

      
           +----------------+-------------+---------------------------+ 
           | sourceAddressA | sourcePortA |     <Flow1 information>   | 
           +----------------+-------------+---------------------------+ 
           | sourceAddressA | sourcePortA |     <Flow2 information>   | 
           +----------------+-------------+---------------------------+ 
      
      
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           | sourceAddressA | sourcePortA |     <Flow3 information>   | 
           +----------------+-------------+---------------------------+ 
           | sourceAddressA | sourcePortA |     <Flow4 information>   | 
           +----------------+-------------+---------------------------+ 
           |      ...       |     ...     |            ...            | 
           +----------------+-------------+---------------------------+ 
         
          Figure ZB: Common and Specific Properties Exported Together 
                                   [RFC5473] 
                                         
      
           +------------------------+-----------------+-------------+ 
           | index for properties A | sourceAddressA  | sourcePortA | 
           +------------------------+-----------------+-------------+ 
           |          ...           |      ...        |     ...     | 
           +------------------------+-----------------+-------------+ 
         
         
           +------------------------+---------------------------+ 
           | index for properties A |     <Flow1 information>   | 
           +------------------------+---------------------------+ 
           | index for properties A |     <Flow2 information>   | 
           +------------------------+---------------------------+ 
           | index for properties A |     <Flow3 information>   | 
           +------------------------+---------------------------+ 
           | index for properties A |     <Flow4 information>   | 
           +------------------------+---------------------------+ 
         
         Figure ZC: Common and Specific Properties Exported Separately  
                             according to [RFC5473] 
                                         
           +----------------+-------------+---------------------------+ 
           | sourceAddressA | sourcePortA |     <Flow1 information>   | 
           +----------------+-------------+---------------------------+ 
                                          |     <Flow2 information>   | 
                                          +---------------------------+ 
                                          |     <Flow3 information>   | 
                                          +---------------------------+ 
                                          |     <Flow4 information>   | 
                                          +---------------------------+ 
                                          |            ...            | 
                                          +---------------------------+ 
         
            Figure ZD: Common and Specific Properties Exported with 
                      Structured Data Information Element 
         

      
      
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        The example in figure ZD could be encoded with a basicList if 
        the <Flow information> represents a single Information Element, 
        with a subTemplateList if the <Flow information> represents a 
        Template Record, or with a subTemplateMultiList if the <Flow 
        information> is composed of different Template Records.  

        Using Structured Data Information Elements as a replacement for 
        the techniques specified in "Reducing Redundancy in IP Flow 
        Information Export (IPFIX) and Packet Sampling (PSAMP) Reports" 
        [RFC5473] offers the advantage that a single Template Record is 
        defined.  Hence the Collectors job is simplified in terms of 
        Template management and combining Template/Options Template 
        Records.  

        However, it must be noted that using Structured Data Information 
        Elements as a replacement for the techniques specified in 
        "Reducing Redundancy in IP Flow Information Export (IPFIX) and 
        Packet Sampling (PSAMP) Reports" only applies to simplified 
        cases.  For example, the "Multiple Data Reduction" (Section 7.1 
        [RFC5473]) might be too complex to encode with Structured Data 
        Information Elements.  

      

     10.2. Relationship with Guidelines for IPFIX Testing 

        [RFC5471] presents a list of tests for implementers of IP Flow 
        Information eXport (IPFIX) compliant Exporting Processes and 
        Collecting Processes.  

        Although [RFC5471] doesn't define any structured data element 
        specific tests, the Structured Data Information Elements can be 
        used in many of the [RFC5471] tests. 

        The [RFC5471] series of test could be useful because the 
        document specifies that every Information Element type should be 
        tested.  However, not all cases from this document are tested in 
        [RFC5471]. 

        The following sections are especially noteworthy: 

          . 3.2.1.  Transmission of Template with fixed size 
             Information Elements 

               - each data type should be used in at least one test. 
                  The new data types specified in Section 4.1. should 
                  be included in this test. 
      
      
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          . 3.2.2. Transmission of Template with variable length 
             Information Elements 

               - this test should be expanded to include Data Records 
                  containing variable length basicList, 
                  subTemplateList, and subTemplateMultiList Information 
                  Elements. 

          . 3.3.1. Enterprise-specific Information Elements 

               - this test should include the export of basicList, 
                  subTemplateList, and subTemplateMultiList Information 
                  Elements containing Enterprise-specific Information 
                  Elements. e.g., see the example in figure B. 

          . 3.3.3. Multiple instances of the same Information Element 
             in one Template 

               - this test should verify that multiple instances of the 
                  basicList, subTemplateList and subTemplateMultiList 
                  Information Elements are accepted. 

          . 3.5 Stress/Load tests 

               - since the structured data types defined here allow 
                  modeling of complex data structures, they may be 
                  useful for stress testing both Exporting Processes 
                  and Collecting Processes. 

      
     10.3. Relationship with IPFIX Mediation Function 

        The Structured Data Information Elements would be beneficial for 
        the export of aggregated Data Records in mediation function, as 
        was demonstrated with the example of the aggregated Observation 
        Point in Section 5.3.  

         

     11. IANA Considerations 

      This document specifies several new IPFIX abstract data types, a 
      new IPFIX Data Type Semantic, and several new Information 
      Elements. 
       
      These require the creation of two new IPFIX registries and 

      
      
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      updating the existing IPFIX Information Element registry as 
      detailed below. 
       
       
     11.1. New Abstract Data Types 

      Section 4.1. of this document specifies several new IPFIX abstract 
      data types.  Per Section 6 of the IPFIX information model 
      [RFC5102], new abstract data types can be added to the IPFIX 
      information model, in the IPFIX Information Element Data Types 
      registry.   
       
      Abstract data types to be added to the IPFIX "Information Element 
      Data Types" registry are listed below. 
       
      EDITOR'S NOTE: IANA, please pick the number three values in the 
      http://www.iana.org/assignments/ipfix/ipfix.xml#informationElement
      DataTypes for the basicList, subTemplateList, and 
      subTemplateMultiList. 
       
       
     11.1.1. basicList 

      The type "basicList" represents a list of any Information Element 
      used for single-valued data types.  
       
       
     11.1.2. subTemplateList 

      The type "subTemplateList" represents a list of a structured data 
      type, where the data type of each list element is the same and 
      corresponds with a single Template Record.  
       
       
     11.1.3. subTemplateMultiList 

      The type "subTemplateMultiList" represents a list of structured 
      data types, where the data types of the list elements can be 
      different and correspond with different template definitions. 
      
      
     11.2. New Data Type Semantics 

     Section 4.2. of this document specifies a new IPFIX Data Type 
     Semantic.  Per Section 3.2 of the IPFIX information model 
     [RFC5102], new data type semantics can be added to the IPFIX 
     information model.  Therefore, the IANA IPFIX 
      
      
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     informationElementSemantics registry [IANA-IPFIX], which contains 
     all the data type semantics from Section 3.2 of [RFC5102], must be 
     augmented with the "list" value below. 
      
         
     11.2.1. list 

      A list is a structured data type, being composed of a sequence of 
      elements e.g. Information Element, Template Record, etc.  
       
       
     11.3. New Information Elements 

      Section 4.3. of this document specifies several new Information 
      Elements which are to be created in the IPFIX Information Element 
      registry [IANA-IPFIX].  
       
      New Information Elements to be added to the IPFIX Information 
      Element registry are listed below. 
       
      EDITOR'S NOTE: the XML specification in Appendix A must be updated 
      with the elementID values allocated below. 
      
     11.3.1. basicList  

      Name: basicList  
      Description:  
      Specifies a generic Information Element with a basicList abstract 
      data type.  For example, a list of port numbers, a list of 
      interface indexes, etc.  
      Abstract Data Type: basicList  
      Data Type Semantics: list  
      ElementId: XXX (to be specified by IANA)  
      Status: current  
      
     11.3.2. subTemplateList 

      Name: subTemplateList  
      Description:  
      Specifies a generic Information Element with a subTemplateList 
      abstract data type.  
      Abstract Data Type: subTemplateList  
      Data Type Semantics: list  
      ElementId: YYY (to be specified by IANA)  
      Status: current 
      

      
      
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     11.3.3. subTemplateMultiList 

      Name: subTemplateMultiList  
      Description:  
      Specifies a generic Information Element with a 
      subTemplateMultiList abstract data type.  
      Abstract Data Type: subTemplateMultiList  
      Data Type Semantics: list  
      ElementId: ZZZ (to be specified by IANA)  
      Status: current 

     11.4. New Structured Data Semantics 

     Section 4.4. of this document specifies a series of new IPFIX 
     structured data type semantics, which is expressed as an 8-bit 
     value.  This requires the creation of a new IPFIX "structured data 
     types semantics" IPFIX subregistry [IANA-IPFIX].   
      
     Entries may be added to this subregistry subject to a Standards 
     Action [RFC5226].  Initially, this registry should include all the 
     structured data type semantics listed below.   
      
      
     11.4.1. undefined 

     Name: undefined 
      
     Description: The "undefined" structured data type semantic 
     specifies that the semantic of list elements is not specified, and 
     that, if a semantic exists, then it is up to the Collecting 
     Process to draw its own conclusions.  The "undefined" structured 
     data type semantic is the default structured data type semantic. 
      
     Value: 0xFF 
      
      Reference: <this future RFC> 
       
       
     11.4.2. noneOf 

     Name: noneOf 
      
     Description: The "noneOf" structured data type semantic specifies 
     that none of the elements are actual properties of the Data 
     Record.  
      
     Value: 0x00 
      
      
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     Reference: <this future RFC> 
       
      
     11.4.3. exactlyOneOf 

     Name: exactlyOneOf 
      
     Description: The "exactlyOneOf" structured data type semantic 
     specifies that only a single element from the structured data is 
     an actual property of the Data Record.  This is equivalent to a 
     logical XOR operation. 
      
     Value: 0x01 
      
     Reference: <this future RFC> 
       
       
     11.4.4. oneOrMoreOf 

     Name: oneOrMoreOf 
      
     Description: The "oneOrMoreOf" structured data type semantic 
     specifies that one or more elements from the list in the 
     structured data are actual properties of the Data Record.  This is 
     equivalent to a logical OR operation. 
      
     Value: 0x02 
      
     Reference: <this future RFC> 
       
     11.4.5. allOf 

     Name: allOf 
      
     Description: The "allOf" structured data type semantic specifies 
     that all of the list elements from the structured data are actual 
     properties of the Data Record. 
      
     Value: 0x03 
      
     Reference: <this future RFC> 
      
       
     11.4.6. ordered 

     Name: ordered 
      
      
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     Description: The "ordered" structured data type semantic specifies 
     that elements from the list in the structured data are ordered. 
      
     Value: 0x04 
      
     Reference: <this future RFC> 
      
      
     12. Security Considerations 

      The addition of complex data types necessarily complicates the 
      implementation of the Collector. This could easily result in new 
      security vulnerabilities (e.g., buffer overflows); this creates 
      additional risk in cases where either DTLS is not used, or if the 
      Observation Point and Collector belong to different trust domains. 
      Otherwise, the same security considerations as for the IPFIX 
      Protocol  [RFC5101] and the IPFIX information model [RFC5102] 
      apply.  
       
       
      
     13. References 

     13.1. Normative References 

        [RFC2119] S. Bradner, Key words for use in RFCs to Indicate 
                Requirement Levels, BCP 14, RFC 2119, March 1997. 
      
        [RFC5101] Claise, B., Ed., "Specification of the IP Flow 
                Information Export (IPFIX) Protocol for the Exchange of 
                IP Traffic Flow Information", RFC 5101, January 2008. 
      
        [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and 
                J. Meyer, "Information Model for IP Flow Information 
                Export", RFC 5102, January 2008. 
         
        [RFC5226] T. Narten, T., Alverstrand, H. , "Guidelines for 
                Writing an IANA Considerations Section in RFCs", 
                RFC5226, May 2008. 
         
         
     13.2. Informative References 

         

      
      
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        [RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander, 
                Requirements for IP Flow Information Export, RFC 3917, 
                October 2004. 
         
        [RFC5103] Trammell, B., and E. Boschi, "Bidirectional Flow 
                Export Using IP Flow Information Export (IPFIX)", RFC 
                5103, January 2008. 
      
        [RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. 
                Quittek, "Architecture for IP Flow Information Export", 
                RFC 5470, March 2009. 
         
        [RFC5471] Schmoll, C., Aitken, P., and B. Claise, "Guidelines 
                for IP Flow Information Export (IPFIX) Testing", RFC 
                5471, March 2009. 
         
        [RFC5472] Zseby, T., Boschi, E., Brownlee, N., and B. Claise, 
                "IP Flow Information Export (IPFIX) Applicability", RFC 
                5472, March 2009. 
         
        [RFC5473] Boschi, E., Mark, L., and B. Claise, "Reducing 
                Redundancy in IP Flow Information Export (IPFIX) and 
                Packet Sampling (PSAMP) Reports", RFC 5473, March 2009. 
      
        [RFC5475] Zseby, T., Molina, M., Duffield, N., Niccolini, S., 
                and F. Raspall, "Sampling and Filtering Techniques for 
                IP Packet Selection", RFC 5475, March 2009. 
      
        [RFC5476] Claise, B., Ed., "Packet Sampling (PSAMP) Protocol 
                Specifications", RFC 5476, March 2009. 
         
        [RFC5477] Dietz, T., Claise, B., Aitken, P., Dressler, F., and 
                G. Carle, "Information Model for Packet Sampling 
                Exports", RFC 5477, March 2009. 
         
        [IANA-IPFIX] http://www.iana.org/assignments/ipfix/ipfix.xhtml 
         

     14. Acknowledgement 

      The authors would like to thank Zhipu Jin, Nagaraj Varadharajan, 
      Brian Trammel, Atsushi Kobayashi, Rahul Patel for their feedback, 
      and Gerhard Muenz, for proof reading the document. 
       
       

      
      
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     15. Authors' Addresses 

       
      Benoit Claise 
      Cisco Systems, Inc. 
      De Kleetlaan 6a b1 
      Diegem 1813 
      Belgium 
          
      Phone: +32 2 704 5622 
      EMail: bclaise@cisco.com 
       
       
      Gowri Dhandapani 
      Cisco Systems, Inc. 
      13615 Dulles Technology Drive 
      Herndon, Virigina 20171 
      United States 
          
      Phone: +1 408 853 0480 
      EMail: gowri@cisco.com 
       
       
      Stan Yates 
      Cisco Systems, Inc. 
      7100-8 Kit Creek Road 
      PO Box 14987 
      Research Triangle Park 
      North Carolina, 27709-4987 
      United States 
          
      Phone: +1 919 392 8044 
      EMail: syates@cisco.com 
       
       
      Paul Aitken 
      Cisco Systems, Inc. 
      96 Commercial Quay 
      Commercial Street 
      Edinburgh, EH6 6LX, United Kingdom 
          
      Phone: +44 131 561 3616 
      EMail: paitken@cisco.com 
      

      
      
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      Appendix A.  Additions to XML Specification of IPFIX Information 
      Elements and Abstract Data Types 

      This appendix contains additions to the machine-readable 
      description of the IPFIX information model coded in XML in 
      Appendix A and Appendix B in [RFC5102].  Note that this appendix 
      is of informational nature, while the text in section 4. 
      (generated from this appendix) is normative. 
       
      The following field definitions are appended to the IPFIX 
      information model in Appendix A of [RFC5102]. 
      
         <field name="basicList" 
                 dataType="basicList" 
                 group="structured-data" 
                 dataTypeSemantics="List" 
                 elementId="XXX" applicability="all" status="current"> 
            <description> 
              <paragraph> 
                 Represents a list of zero or more instances of 
                 any Information Element, primarily used for 
                 single-valued data types. For example, a list of port 
                 numbers, list of interface indexes, list of AS in a  
                 BGP AS-PATH, etc. 
              </paragraph> 
            </description> 
          </field> 
            
          <field name="subTemplateList" 
                 dataType="subTemplateList" 
                 group="structured-data" 
                 dataTypeSemantics="List" 
                 elementId="YYY" applicability="all" status="current"> 
            <description> 
              <paragraph> 
                 Represents a list of zero or more instances of a 
                 structured data type, where the data type of each list 
                 element is the same and corresponds with a single 
                 Template Record. For example, a structured data type 
                 composed of multiple pairs of ("MPLS label stack entry 
                 position", "MPLS label stack value"), a structured data 
                 type composed of performance metrics, a structured data 
                 type composed of multiple pairs of IP address, etc. 
              </paragraph> 
            </description> 
      
      
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          </field> 
         
          <field name="subTemplateMultiList"               
                 dataType="subTemplateMultiList" 
                 group="structured-data" 
                 dataTypeSemantics="List" 
                 elementId="ZZZ" applicability="all" status="current"> 
            <description> 
              <paragraph> 
                Represents a list of zero or more instances of 
                structured data types, where the data type of each list 
                element can be different and corresponds with 
                different template definitions. For example, a  
                structured data type composed of multiple access-list  
                entries, where entries can be composed of different  
                criteria types. 
              </paragraph> 
            </description> 
          </field> 
       
       
      The following structured data type semantic definitions are 
      appended to the the IPFIX information model in Appendix A of 
      [RFC5102]. 
       
       
        <structuredDataTypeSemantics> 
          <structuredDataTypeSemantic name="undefined" value="255"> 
            <description> 
              <paragraph> 
               The "undefined" structured data type semantic specifies 
               that the semantic of list elements is not specified, and 
               that, if a semantic exists, then it is up to the 
               Collecting Process to draw its own conclusions.  The 
               "undefined" structured data type semantic is the default 
               structured data type semantic. 
              </paragraph> 
            </description> 
          </structuredDataTypeSemantic> 
         
          <structuredDataTypeSemantic name="noneOf" value="0"> 
            <description> 
              <paragraph> 
               The "noneOf" structured data type semantic specifies 
               that none of the elements are actual properties of the 
               Data Record.  
              </paragraph> 
      
      
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            </description> 
          </structuredDataTypeSemantic> 
         
          <structuredDataTypeSemantic name="exactlyOneOf" value="1"> 
            <description> 
              <paragraph> 
               The "exactlyOneOf" structured data type semantic 
               specifies that only a single element from the structured 
               data is an actual property of the Data Record.  This is 
               equivalent to a logical XOR operation. 
              </paragraph> 
            </description> 
          </structuredDataTypeSemantic> 
         
          <structuredDataTypeSemantic name="oneOrMoreOf" value="2"> 
            <description> 
              <paragraph> 
               The "oneOrMoreOf" structured data type semantic 
               specifies that one or more elements from the list in the 
               structured data are actual properties of the Data 
               Record.  This is equivalent to a logical OR operation. 
              </paragraph> 
            </description> 
          </structuredDataTypeSemantic> 
          
          <structuredDataTypeSemantic name="allOf" value="3"> 
            <description> 
              <paragraph> 
               The "allOf" structured data type semantic specifies that 
               all of the list elements from the structured data are 
               actual properties of the Data Record. 
              </paragraph> 
            </description> 
          </structuredDataTypeSemantic> 
          
          <structuredDataTypeSemantic name="ordered" value="4"> 
            <description> 
              <paragraph> 
               The "ordered" structured data type semantic specifies 
               that elements from the list in the structured data are 
               ordered.       
              </paragraph> 
            </description> 
          </structuredDataTypeSemantic> 
        </structuredDataTypeSemantics> 
      
       
      
      
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      The following schema definitions are appended to the abstract data 
      types defined in Appendix B of [RFC5102].  This schema and its 
      namespace are registered by IANA at 
      http://www.iana.org/assignments/xml-registry/schema/ipfix.xsd 
       
       
       
        <simpleType name="dataType"> 
          <restriction base="string"> 
            <enumeration value="basicList"> 
              <annotation> 
                <documentation> 
                  Represents a list of zero or more instances of 
                  any Information Element, primarily used for 
                  single-valued data types. For example, a list of port 
                  numbers, list of interface indexes, list of AS in a 
                  BGP AS-PATH, etc. 
                </documentation> 
              </annotation> 
            </enumeration> 
            <enumeration value="subTemplateList"> 
              <annotation> 
                <documentation> 
                  Represents a list of zero or more instances of a 
                  structured data type, where the data type of each list 
                  element is the same and corresponds with a single 
                  Template Record. For example, a structured data type 
                  composed of multiple pairs of ("MPLS label stack entry 
                  position", "MPLS label stack value"), a structured 
                  data type composed of performance metrics, a 
                  structured data type composed of multiple pairs of IP 
                  address, etc. 
                </documentation> 
              </annotation> 
            </enumeration> 
            <enumeration value="subTemplateMultiList"> 
              <annotation> 
                <documentation> 
                  Represents a list of zero or more instances of 
                  structured data types, where the data type of each 
                  list element can be different and corresponds with 
                  different template definitions. For example, a 
                  structured data type composed of multiple  
                  access-list entries, where entries can be  
                  composed of different criteria types. 
                </documentation> 
              </annotation> 
      
      
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            </enumeration> 
          </restriction> 
        </simpleType> 
         
        <simpleType name="dataTypeSemantics"> 
          <restriction base="string"> 
            <enumeration value="List"> 
              <annotation> 
                <documentation> 
                  Represents an arbitrary-length sequence of structured 
                  data elements, either composed of regular Information 
                  Elements or composed of data conforming to a Template 
                  Record.               
                </documentation> 
              </annotation> 
            </enumeration> 
          </restriction> 
        </simpleType> 
         
        <complexType name="structuredDataTypeSemantics"> 
          <sequence> 
            <element name="structuredDataTypeSemantic" 
                     minOccurs="1" maxOccurs="unbounded"> 
              <complexType> 
                <sequence> 
                  <element name="description" type="text"/> 
                </sequence> 
                <attribute name="name" type="string" use="required"/> 
                <attribute name="value" type="unsignedByte" 
      use="required"/> 
              </complexType> 
            </element> 
          </sequence> 
        </complexType> 
       
        <element name="structuredDataTypeSemantics" 
                 type="structuredDataTypeSemantics"> 
          <annotation> 
            <documentation> 
              structured data type semantics express the relationship 
              among multiple list elements in a structured data 
              Information Element. 
            </documentation> 
          </annotation> 
        </element> 
      
       
      
      
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      Appendix B.  Encoding IPS Alert using Structured Data Information 
      Elements 

      In this section, an IPS alert example is used to demonstrate how 
      complex data and multiple levels of hierarchy can be encoded using 
      Structured Data Information Elements.  Also, this example 
      demonstrates how a basicList of subTemplateLists can be used to 
      represent semantics at multiple levels in the hierarchy.  
       
      An IPS alert consists of the following mandatory attributes:  
      signatureId, protocolIdentifier and riskRating.  It can also 
      contain zero or more participants, each participant can contain 
      zero or more attackers and zero or more targets.  An attacker 
      contains the attributes sourceIPv4Address and applicationId, and 
      a target contains the attributes destinationIPv4Address and 
      applicationId. 
       
      Note that the signatureId and riskRating Information Element 
      fields are created for these examples only; the Field IDs are 
      shown as N/A.  The signatureId helps to uniquely identify the IPS 
      signature that triggered the alert.  The riskRating identifies the 
      potential risk, on a scale of 0-100 (100 being most serious), of 
      the traffic that triggered the alert. 
       
      Consider the example described in case study 2 of Section 5.6. The 
      IPS alert contains participants encoded as a subTemplateList with 
      semantic allOf.  Each participant uses a basicList of 
      subTemplateLists to represent attackers and targets.  For the sake 
      of simplicity, the alert has two participants P1 and P2.  In 
      participant P1, attacker A1 or A2 attack target T1.  In 
      participant P2, attacker A3 attacks targets T2 and T3.  
       
     Participant P1: 

          (basicList, allof,  

                (subTemplateList, exactlyOneOf, attacker A1, A2) 

                (subTemplateList, undefined, target T1) 

          ) 

     Participant P2: 

          (basicList, allOf,  

                (subTemplateList, undefined, attacker A3, 
      
      
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                (subTemplateList, allOf, targets T2, T3) 

          ) 

     Alert : 

             (subTemplateList, allOf, Participant P1, Participant P2) 

       
      ------------------------------------------------------------------ 
            |        |        |             participant  
      sigId |protocol| risk   |      attacker   |      target            
            |   Id   | Rating |    IP   | appId |    IP      | appId 
      ------------------------------------------------------------------ 
      1003     17      10      192.0.2.3  103    192.0.2.103    3001 
                               192.0.2.4  104    
       
                               192.0.2.5  105    192.0.2.104    4001 
                                                 192.0.2.105    5001 
      ------------------------------------------------------------------ 
       
      Participant P1 contains: 
      Attacker A1: (IP, appID)=(192.0.2.3, 103) 
      Attacker A2: (IP, appID)=(192.0.2.4, 104) 
      Target T1: (IP, appID)= (192.0.2.103, 3001) 
       
      Participant P2 contains: 
      Attacker A3: (IP, appID) = (192.0.2.5, 105) 
      Target T2: (IP, appID)= (192.0.2.104, 4001) 
      Target T3: (IP, appID)= (192.0.2.105, 5001) 
       
       
      To represent an alert, the following Templates are defined: 
      Template for target (268) 
      Template for attacker (269) 
      Template for participant (270) 
      Template for alert (271) 
       
           alert (271) 
           |  (signatureId) 
           |  (protocolIdentifier) 
           |  (riskRating) 
           | 
           +------- participant (270) 
                    | 
                    +------- attacker (269) 
                    |           (sourceIPv4Address) 
      
      
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                    |           (applicationId) 
                    | 
                    +------- target (268) 
                             |  (destinationIPv4Address) 
                             |  (applicationId) 
                              
      Note that the attackers are always composed of a single 
      applicationId, while the targets typically have multiple 
      applicationId, for the sake of simplicity this example shows only 
      one applicationId in the target. 
       
      Template Record for target, with the Template ID 268: 
       
      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 = 16 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |       Template ID = 268       |       Field Count = 2         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0| destinationIPv4Address = 12 |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|       applicationId = 95    |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
               Figure B0: Encoding IPS Alert, Template for Target 
      
       
      Template Record for attacker, with the Template ID 269: 
       
       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 = 16 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |       Template ID = 269       |       Field Count = 2         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|    sourceIPv4Address = 8    |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|     applicationId = 95      |       Field Length = 4        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
              Figure B1: Encoding IPS Alert, Template for Attacker 
       
       
      Template Record for participant, with the Template ID 270: 
       
      
      
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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 = 12 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |       Template ID = 270       |       Field Count = 1         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|       basicList = XXX       |     Field Length = 0xFFFF     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
                        
            Figure B2: Encoding IPS Alert, Template for Participant 
       
       
      The Template Record for the participant has one basicList 
      Information Element, which is a list of subTemplateLists of 
      attackers and targets. 
          
      Template Record for IPS alert, with the Template ID 271: 
       
       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 = 24 octets       | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |       Template ID = 271       |       Field Count = 4         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|    signatureId = N/A        |       Field Length = 2        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|   protocolIdentifier = 4    |       Field Length = 1        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|     riskRating = N/A        |       Field Length = 1        | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |0|     subTemplateList = YYY   |     Field Length = 0xFFFF     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
             Figure B3: Encoding IPS Alert, Template for IPS Alert 
       
      The subTemplateList in the alert Template Record contains a list 
      of participants.   
       
      The Length of basicList and subTemplateList are encoded in three 
      bytes even though they may be less than 255 octets. 
       
       
      The Data Set is represented as follows: 
        
       
      
      
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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 = 271         |         Length = 102          | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      signatureId = 1003       | protocolId=17 | riskRating=10 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |participant List Length  = 91  |semantic=allOf | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | participant Template ID = 270 |     255       | P1 List Len = | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      41       | semantic=allOf|    P1 List Field ID = YYY     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | P1 List Field ID Len = 0xFFFF |      255      |P1 attacker ...| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | List Len = 19 |sem=exactlyOne | P1 attacker Template ID = 269 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          P1 attacker A1 sourceIPv4Address = 192.0.2.3         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |               P1 attacker A1 applicationId = 103              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          P1 attacker A2 sourceIPv4Address = 192.0.2.4         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |               P1 attacker A2 applicationId = 104              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      | P1 target List Len = 11       | sem=undefined | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |  P1 target Template ID = 268  | P1 target T1 destinationIPv4  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ... Address = 192.0.2.103     |P1 target T1 applicationId =...| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...       3001                |      255      | P2 List Len = | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...  41       | semantic=allOf|    P2 List Field ID = YYY     | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | P2 List Field ID Len = 0xFFFF |      255      |P2 attacker ...| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | List Len = 11 | sem=undefined | P2 attacker Template ID = 269 | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |          P2 attacker A3 sourceIPv4Address = 192.0.2.5         | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |               P2 attacker A3 applicationId = 105              | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |      255      |    P2 target List Len = 19    |semantic=allOf | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      |  P2 target Template ID = 268  | P2 target T2 destinationIPv4  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      
      
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      | ... Address = 192.0.2.104     |P2 target T2 applicationId =...| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...       4001                | P2 target T3 destinationIPv4  | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ... Address = 192.0.2.105     |P2 target T3 applicationId =...| 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
      | ...       5001                | 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       
                    Figure B4: Encoding IPS Alert, Data Set 
        
       

      
      
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