One document matched: draft-ietf-ipfix-export-per-sctp-stream-00.txt





     IPFIX Working Group                                    B. Claise 
     Internet-Draft                                         P. Aitken 
     Intended Status: Informational                        A. Johnson 
     Expires: January 1, 2009                     Cisco Systems, Inc.   
                                                             G. Muenz 
                                              University of Tuebingen 
                                                         July 1, 2008 
      
                       IPFIX Export per SCTP Stream 
                draft-ietf-ipfix-export-per-sctp-stream-00 


     Status of this Memo 

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        This Internet-Draft will expire on June, 2008. 
         
     Copyright Notice  
         
        Copyright (C) The IETF Trust (2008).










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     Abstract 

        This document specifies an improvement to the use of SCTP 
        as specified in the IPFIX specifications in order to be 
        able to deduce the Data Record loss per Template Record in 
        case of partially-reliable SCTP export.  This specification 
        offers several extra advantages: immediate export of the 
        Template Withdrawal Message, immediate reuse of Template ID 
        within a stream, and the Collecting Process's job is 
        easier. 
         
     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]. 
      

     Table of Contents 

         
        1. Terminology.................................................4 
           1.1. IPFIX Documents Overview...............................4 
           1.2. PSAMP Documents Overview...............................4 
        2. Introduction................................................5 
           2.1. Relationship with IPFIX and PSAMP......................6 
           2.2. Applicability..........................................6 
           2.3. Limitations............................................7 
        3. IPFIX Protocol Specifications Limitations and 
        Improvements...................................................7 
           3.1. Data Record Loss per Template..........................7 
              3.1.1. IPFIX Protocol Specifications Limitation..........7 
              3.1.2. IPFIX Export per SCTP Stream Advantage............8 
           3.2. Transmission Order within a Stream.....................8 
              3.2.1. IPFIX Protocol Specifications Limitation..........8 
              3.2.2. IPFIX Export per SCTP Stream Advantages...........9 
           3.3. No Transmission Order across SCTP Streams.............10 
              3.3.1. IPFIX Protocol Specifications Limitation.........10 
              3.3.2. IPFIX Export per SCTP Stream Advantages..........10 
        4. Specifications.............................................10 
           4.1. Template Management...................................10 
           4.2. New Information Element...............................12 
           4.3. SCTP..................................................12 
           4.4. Template Withdrawal Message...........................13 
           4.5. The Collecting Process's Side.........................13 
      
      
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        5. Examples...................................................14 
        6. IANA Considerations........................................16 
        7. Security Considerations....................................16 
        8. References.................................................17 
           8.1. Normative References..................................17 
           8.2. Informative References................................17 
        9. Acknowledgements...........................................18 
        10. Author's Addresses........................................19 
        11. Intellectual Property Statement...........................20 
        12. Copyright Statement.......................................20 
        13. Disclaimer................................................20 
         



































      
      
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     1. Terminology 

        IPFIX-specific terminology used in this document is defined 
        in section 2 of [RFC5101].  As in [RFC5101], these IPFIX-
        specific terms have the first letter of a word capitalized 
        when used in this document. 
         
        Template Reuse Delay  
         
           The configurable timeout to allow the Collecting Process 
           to receive and process the last Data Record using this 
           Template information before which the Template Withdrawal 
           Message MUST NOT be sent.  [RFC5101] specifies a default 
           value of 5 seconds. 
         

     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 [IPFIX-ARCH], 
        per the requirements defined in RFC 3917 [RFC3917]. 
         
        The IPFIX Architecture [IPFIX-ARCH] 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].   
         
        Finally the IPFIX Applicability Statement [IPFIX-AS] 
        describes what type of applications can use the IPFIX 
        protocol and how they can use the information provided.  It 
        furthermore shows how the IPFIX framework relates to other 
        architectures and frameworks.  
         
     1.2. PSAMP Documents Overview 

        The document "A Framework for Packet Selection and Reporting" 
        [PSAMP-FMWK], describes the PSAMP framework for network 
        elements to select subsets of packets by statistical and 
      
      
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        other methods, and to export a stream of reports on the 
        selected packets to a collector. 
         
        The set of packet selection techniques (sampling, filtering, 
        and hashing) supported by PSAMP are described in "Sampling 
        and Filtering Techniques for IP Packet Selection" [PSAMP-
        TECH]. 
         
        The PSAMP protocol [PSAMP-PROTO] 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 [PSAMP-INFO]. 
         
        Finally [PSAMP-MIB] describes the PSAMP Management 
        Information Base. 
         

     2. Introduction 

        The IPFIX working group has specified a protocol to export IP 
        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.).  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, or specified as an enterprise-specific 
        Information Element. 
         
        The IPFIX protocol [RFC5101] specifies that IP 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. 
         
        The IPFIX protocol [RFC5101] is flexible: it foresees the usage 
        of the multiple SCTP streams per association; it allows the 
        transmission of Data Sets, Template Sets, and/or Options 
        Template Sets on any stream; it offers the full or partial 
        reliability export of Data Sets; it proposes the ordered or out-
        of-order delivery of Data Sets.  However, due to bandwidth 
      
      
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        restrictions and packet losses in the network as well as 
        resource constraints on the Exporter and Collector (e.g., 
        limited buffer sizes), it is not always possible to export all 
        Data Sets in a reliable way. 
         
         
        Without delving into the details of the specifications described 
        later on in this document, the basic idea is to export the 
        Template Record and its associated Data Sets into a single 
        unique SCTP stream, ideally to limit the Template ID to a single 
        stream, while imposing in-order transmission. 
         
        The specification in this document offers several advantages 
        such as: calculation of Data Record losses in case of partially-
        reliable SCTP export, immediate export of the Template 
        Withdrawal Message, immediate reuse of template ID within a 
        stream, reduced likelihood of losing Data Record, and the 
        Collecting Process's job is easier. 
      
         
     2.1. Relationship with IPFIX and PSAMP 

        The specification in this document applies to the IPFIX 
        protocol specifications [RFC5101].  However, it only applies 
        to the SCTP transport protocol [RFC4960] option of the IPFIX 
        protocol specifications, specifically in the case of the 
        partial reliability extension [RFC3758].  All specifications 
        from [RFC5101] apply unless specified otherwise in this 
        document. 
      
        As the Packet Sampling (PSAMP) protocol specifications 
        [PSAMP-PROTO] are based on the IPFIX protocol specifications, 
        the specifications in this document are also valid for the 
        PSAMP protocol.  Therefore, the advantages specified by this 
        document also apply to PSAMP. 
         
      
     2.2. Applicability 

        The specifications are required in cases where we must know how 
        many Data Records of a certain type (i.e. from a certain 
        Template ID) were lost.  Furthermore, they apply in cases where 
        the Exporter can not afford to export all the Flow Records 
        reliably, due to the limited resources to buffer the huge amount 
        of flow records.  Such situations may occur if Data Sets are 
        generated at a higher rate at the Exporter than can be 
        transferred to the Collector because of bandwidth limitations in 
      
      
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        the network or slow reception at the Collector.  A typically 
        example is a router exporting billing records.  
      
        To be more precise, the specification applicability is the case 
        where multiple Template IDs are sent within a SCTP Transport 
        Session and the calculation of the Data Record loss for a 
        particular one Template ID is required.  Indeed, with the 
        current IPFIX specifications [RFC5101], if an IPFIX Message is 
        lost (UDP or SCTP partially reliable), it is not possible to 
        determine to which Template ID of the Transport Session the lost 
        Data Records belong to. 
           
        In terms of Collector, there is backwards compatibility: the 
        Collecting Process does not require any changes to support an 
        Exporter that complies to the specifications in this document. 
         
      
     2.3. Limitations 

        To be compliant with the specifications in this document, the 
        Transport Session must support multiple SCTP streams. 
        Furthermore, if the SCTP Transport Session does not support 
        enough streams for the increasing number of Template ID in the 
        Transport Session, the addition of streams must be supported 
        according to [SCTP-RESET].  Alternatively, the new Template ID 
        and associated Data Records may be added to an existing stream 
        at the cost of diluting the granularity of Data Records loss.  
        The other alternatives, which is not practical in operational 
        networks, is to restart the SCTP association with an increase 
        number of streams. 
         

     3. IPFIX Protocol Specifications Limitations and Improvements   

     3.1. Data Record Loss per Template 

     3.1.1. IPFIX Protocol Specifications Limitation 

        Section 6.3.2 of the Requirements for IP Flow Information 
        Export [RFC3917] discusses the data transfer reliability 
        issues.  "Loss of flow records during the data transfer from 
        the exporting process to the Collecting Process must be 
        indicated at the collecting process." is clearly mentioned.   
        However, in some cases, it may be important to know how many 
        Data Records of a certain type were lost (e.g., in the case 
        of billing), but conventionally IPFIX does not provide this 
        information. 
      
      
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        A Collector can detect out-of-sequence, dropped, or duplicate 
        IPFIX Messages by tracking the Sequence Number [RFC5101].  
        Note that the Sequence Number field in the Export header 
        increases with the number of IPFIX Data Records within the 
        PR-SCTP stream.  
         
        The IPFIX protocol specification [RFC5101] specifies that Data 
        Records associated with any Template ID may be sent on any SCTP 
        stream.  As such, if there is more than one Template IDs defined 
        within the whole SCTP association then there is no way of 
        knowing which Template ID any lost Data Records are associated 
        with.  This is true, no matter what convention the Exporting 
        Process uses to send Data Records on different SCTP streams, as 
        the protocol makes no guarantees. 
         
        Using the specification in this document, it is guaranteed that 
        any lost Data Records will be associated only with the Templates 
        that are defined on that stream and by defining only one 
        Template on a stream it is ensured that any loss is associated 
        with that single Template. 
      
         
     3.1.2. IPFIX Export per SCTP Stream Advantage 

        By exporting each Template ID and the corresponding Data Records 
        within a different stream, the loss pertaining to each specific 
        Template ID can be deduced from the Sequence Number field in the 
        IPFIX Message headers. 
         
         
     3.2. Transmission Order within a Stream 

     3.2.1. IPFIX Protocol Specifications Limitation 

        A Collecting Process must have received the Template Record 
        associated with the Data Records to be able to decode the 
        information in the Data Records.  The IPFIX protocol 
        specification foresees: 
         
           "The Exporting Process SHOULD transmit the Template Set 
           and Options Template Set in advance of any Data Sets that 
           use that (Options) Template ID, to help ensure that the 
           Collector has the Template Record before receiving the 
           first Data Record.", 
         

      
      
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        The fact that the Collecting Process cannot decode the Data 
        Records without the Template Record may result in the Data 
        Records being discarded by the Collector, as specified in 
        [RFC5101]:  
         
           "The Collecting Process normally receives Template Records 
           from the Exporting Process before receiving Data Records.  
           The Data Records are then decoded and stored by the 
           Collector.  If the Template Records have not been received 
           at the time Data Records are received, the Collecting 
           Process MAY store the Data Records for a short period of 
           time and decode them after the Template Records are 
           received."  
      
        In practice, Data Records without associated (Options) 
        Template Records will probably be discarded by the Collecting 
        Process. 
      
         
     3.2.2. IPFIX Export per SCTP Stream Advantages 

        By exporting each Template Record and the corresponding Data 
        Records within a single stream and imposing in-order 
        transmission, the Template will always arrive before the 
        associated Data Records.  Therefore, there is no risk that 
        the Collecting Process discards Data Records while waiting 
        for the Template to arrive. 
         
        Furthermore, when reusing a Template ID within a stream, the 
        Template Withdrawal Message will be guaranteed to arrive 
        before the new definition of the Template and therefore the 
        Template Record may be sent directly after the Template 
        Withdrawal Message.  In other words, the Template Reuse Delay 
        restriction (by default, 5 seconds, as specified in [RFC5101] 
        is removed for Template ID reuse within the same stream. 
         
        Another advantage with the new specifications in this 
        document is that the Collecting Process's job is now easier.  
        Indeed, the Collecting Process doesn't have to store the Data 
        Records while waiting for the Template Records, as the 
        transmission order is always guaranteed.  This way, extra 
        reliability of the Data Records is achieved without extra 
        burden on the Collecting Process. 
         
         


      
      
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     3.3. No Transmission Order across SCTP Streams 

     3.3.1. IPFIX Protocol Specifications Limitation 

        The fact that the protocol specifications [RFC5101] are 
        flexible in terms of stream(s) on which the Template Set, 
        Options Template Set, and corresponding Data Sets are 
        exported, implies that the (Options) Template Set might be 
        exported on a different stream than the corresponding Data 
        Sets.  This might cause Data Record loss in the Collecting 
        Process as the ordered transmission across SCTP streams is 
        not guaranteed.  
      
        For example, a Template may be blocked pending reliable 
        transmission on one stream while the associated Data Records 
        may be transmitted immediately in another stream.  Also, due 
        to different stream congestion, it is possible that even if 
        the Template and Data Records are both sent reliably, Data 
        Records sent on a different stream than the associated 
        Template might still arrive before the associated Template.  
         
         
     3.3.2. IPFIX Export per SCTP Stream Advantages 

        By exporting each Template Record and the corresponding Data 
        Records within a single stream, imposing in-order 
        transmission, and limiting the Template ID to a single 
        stream, the issue of ordered transmission across multiple 
        streams is avoided.  
         
        By exporting all corresponding Data Records within the same 
        ordered stream as the Template Definition, each stream is 
        independent and self-contained and the interaction between 
        streams is limited to that of Options Data interactions.  This 
        has several advantageous consequences, including the order 
        preservation that does not result in the blocking of unrelated 
        data and the Collector's job simplification (as the Template 
        Records are guaranteed to be delivered before the associated 
        Data Records). 
         
         
     4. Specifications 

     4.1. Template Management 

        This section introduces modifications compared to the Template 
        Management section 8 in [RFC5101]. 
      
      
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        As specified in [RFC5101], Template Sets and Options Template 
        Sets MUST be sent reliably.  In other words, any IPFIX Message 
        containing an (Options) Template Set MUST be sent reliably.   
         
        Any Data Sets associated with a Template Record MUST be sent on 
        the same stream on which the Template Record was sent. 
         
        The Exporter SHOULD send a single Template and associated Data 
        Sets within a single stream in order to calculate the potential 
        Data Record loss for this Template ID.  However, the Exporter 
        MAY group related Templates and their associated Data Sets 
        within a single stream so loss statistics are calculated for the 
        group.  This may be suitable in cases where there is 
        insufficient SCTP streams to send each Template on its own 
        stream and/or the case where there are slight variations on a 
        single Template to show that some fields were unavailable at the 
        time of monitoring. 
      
        If a SCTP stream contains a mixture of Data Records defined by a 
        Template Record and Options Template Record(s), the Data Records 
        defined by the Options Template Record(s) SHOULD be sent 
        reliably within the same stream so that the Collector does not 
        consider any loss to be associated with the Options Data.  
        Indeed, if the Collector does not have the guarantee that the 
        Data Records defined by the Options Template Record are sent 
        reliably, the Collector can not determine whether the loss in 
        that stream belongs to the Data Records defined by the Template 
        Record, defined by the Option Template Record, or by both of 
        them.  By sending the Options Data reliably (which is usually 
        required to interpret the Data Records correctly), any loss will 
        be limited to the non-option Data Record and loss can still be 
        calculated on a per Template basis. 
         
        For each (Options) Template Record, the Exporting Process MUST 
        send the Data Record Reliability Option Template using an Option 
        Template with the following Information Elements:  
          
         SCOPE:     Template ID  
         NOT-SCOPE: dataRecordsReliability 
         
        The Data Record Reliability Option Template MUST be sent 
        reliably. 
         


      
      
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        The Option Data Record SHOULD be sent before the Data Record 
        that needs it so that it arrives first and is available for the 
        Collector to use. 
      
         
     4.2. New Information Element 

        dataRecordsReliability 
         
           Description: 
                The Data Records reliability associated with this 
                Template ID.  The integer value 1 means that the Data 
                Records are sent reliably, while the integer value 2 
                means that the Data Records are not sent reliably. 
           Abstract Data Type: boolean 
           Data Type Semantics: identifier 
           ElementId: xxx 
           Status: current 
      
         
     4.3. SCTP 

        This section introduces modifications compared to the "SCTP" 
        section 10.2 (and subsections) in [RFC5101].  More specifically 
        the "Stream" section 10.2.4.3  
         
        PR-SCTP [RFC3758] MUST be implemented by all compliant 
        implementations. 
         
        All IPFIX Messages MUST be sent in order within a stream. 
      
        Depending on the application requirement, the Exporting Process 
        MAY send Data Sets with full or partial reliability.  Unreliable 
        data transfer MAY be used where the application does not require 
        reliable transmission or the use of a retransmission queue is 
        impractical due to resource restrictions at the Exporter. 
         
         
        If the Exporting Process requires to export a new Template but 
        there are no more free SCTP streams available, it SHOULD attempt 
        to increase the number of outbound streams it is able to send 
        to, per [SCTP-RESET].  Alternatively, the Exporting Process MAY 
        add the Template Set and Data Records to an existing stream at 
        the cost of diluting the granularity of Data Records loss. 
      
         

      
      
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     4.4. Template Withdrawal Message 

        This section introduces Template Withdrawal Message-related 
        modifications compared to the Template Management section 8 in 
        [RFC5101]. 
         
        Templates that are not used anymore SHOULD be deleted.  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.  The Template 
        Withdrawal Message MUST be sent on the same stream as the 
        Template Record.  
         
        As the Template Withdrawal Message MUST be sent reliably, using 
        SCTP-ordered delivery per [RFC5101], and as all IPFIX Messages 
        are sent in order within a stream (per the specifications in 
        this document), the IPFIX Message containing the Template 
        Withdrawal Message will not arrive at the Collecting Process 
        before any associated and previously sent Data Record.  As a 
        consequence, no Data Records will be lost due to delayed arrival 
        at the Collector. 
      
        The Template ID from a withdrawn Template MAY be reused on the 
        same stream immediately after the Template Withdrawal Message is 
        sent.  This case is equivalent to the use of a Template Reuse 
        Delay value of 0.  
      
        If the new definition of the Template ID is to be reused on a 
        different stream, the Template Withdrawal Message MUST NOT be 
        sent before the Template Reuse Delay. 
       
        A Template Withdrawal Message to withdraw all Templates for the 
        Observation Domain ID specified in the IPFIX Message header MUST 
        NOT be used.  
         
        Multiple Template IDs MAY be withdrawn with a single Template 
        Withdrawal Message at the condition that all the Template IDs in 
        the Template Withdrawal Message are used on the same SCTP 
        stream. 
      
         
     4.5. The Collecting Process's Side 

        This section introduces modifications to the Collection Process 
        as compared to section 9 in [RFC5101]. 
         

      
      
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        The Collecting Process SHOULD listen for a new association 
        request from the Exporting Process.  The Exporting Process will 
        request a number of streams to use for export: the number of 
        streams SHOULD be equivalent to the number of simultaneous 
        Template Records used in the association. Note that the Template 
        Records don't include the Options Template Records. 
         
        A Collecting Process SHOULD support the procedure for the 
        addition of an SCTP stream [SCTP-RESET]. 
                       
        The IPFIX protocol has a Sequence Number field in the IPFIX 
        Message header that increases with the number of IPFIX Data 
        Records in the IPFIX Message.  A Collector may detect out-of-
        sequence, dropped, or duplicate IPFIX Messages by tracking the 
        Sequence Number.  As this Sequence Number is per SCTP stream, 
        the loss for the Data Records sent in that stream can be 
        calculated in case of partially-reliable export. 
         
        If the Collecting Process receives a Template Withdrawal Message 
        on a different stream than the one on which the Template ID is 
        used, then the Collecting Process MUST reset the association and 
        SHOULD log an error message. 
         
        The following sentences from [RFC5101] are not applicable in 
        this specification: 
         
           "The Collecting Process normally receives Template Records 
           from the Exporting Process before receiving Data Records.  
           The Data Records are then decoded and stored by the 
           Collector.  If the Template Records have not been received at 
           the time Data Records are received, the Collecting Process 
           MAY store the Data Records for a short period of time and 
           decode them after the Template Records are received."  
      
         
     5. Examples 

        Figure 1 shows an example where the stream 10 carries a Template 
        with the Template ID 256 transmitted with full reliability (FR), 
        together with associated Data Records transmitted with partial 
        reliability (PR).  Note that, because all IPFIX Messages are 
        sent in order within a stream, the Template 256 will always be 
        processed before the Data Records by the Collecting Process. 
        Therefore, the Collecting Process job is simplified. 
        Furthermore, the Data Record loss for the Template 256 can 
        easily be calculated on the Collecting Process. 

      
      
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                      +--------+       +---------+   +----------+   
                      |        |       |         |   |          |      
        stream 10 ----| Data   | . . . |  Data   |---| Template |---> 
                      |   256  |       |    256  |   |     256  | 
                      |      PR|       |       PR|   |        FR|       
                      +--------+       +---------+   +----------+   
                                     Figure 1     
         
        If an Option Template is necessary to understand the content of 
        a Data Record (i.e. the scope in the Options Template Record is 
        an Information Element contained in the Data Record), the 
        Options Template Record may be sent in the same stream, as 
        displayed in figure 2. 
         
                         +--------+   +--------+     +----------+     
                         |        |   |        |     |          |     
        stream 20 ... ---| Data   |...| Data   |-----| Template |--- 
                         |   258  |   |   258  |     |     258  |    
                         |      PR|   |      PR|     |        FR|    
                         +--------+   +--------+     +----------+   
         
                                +--------+       +----------+       
                                |        |       | Options  |       
                          ...---| Data   |-------| Template |------> 
                                |   257  |       |     257  |       
                                |      FR|       |        FR|       
                                +--------+       +----------+  
                                     Figure 2               
         
        Figure 2 shows an example where stream 20 carries an Options 
        Template with Template ID 257 transmitted with full reliability 
        (FR), an associated Data Record transmitted with full 
        reliability (FR), a Template with Template ID 258 transmitted 
        with full reliability (FR), and associated Data Records 
        transmitted with partial reliability (PR).  In this example the 
        Option Template Record contains information required to decode 
        the latter Data Records, such as Common Properties information 
        [IPFIX-RED-RED].  So it makes sense to export the Data Sets 257 
        reliably.  If some Data Record loss is observed from the 
        Sequence Number , the loss can only stem from the Data Sets with 
        the Template ID 258, as these are the only Sets not exported 
        reliably.  Therefore, the calculation of loss per Template ID 
        258 is possible.  



      
      
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        Note that, because all IPFIX Messages must be sent in order 
        within a stream, the Options Template 257 will always arrive 
        before its associated Data Records, and that the Template 259 
        will always arrive before the its associated Data Records.  
         
        Figure 3 shows an example where stream 30 carries a Template 
        with Template ID 259 transmitted with full reliability (FR), an 
        associated Data Record transmitted with partial reliability 
        (PR), a Template Withdrawal Message, followed by a redefinition 
        of the Template ID 259, and finally the new definition of Data 
        Record transmitted with partial reliability.  The Template 
        Withdrawal Message and the new definition of the Template ID 259 
        are sent immediately, without waiting for the Template Reuse 
        Delay.  
         
         
                         +--------+   +----------+     +----------+     
                         |        |   |          |     | Template |     
        stream 30 ... ---| Data   |...| Template |-----| Withdraw.|--- 
                         |   259  |   |   259    |     |    259   |    
                         |      PR|   |        FR|     |        FR|    
                         +--------+   +----------+     +----------+   
         
                                +--------+       +----------+       
                                |        |       |          |       
                          ...---| Data   |-------| Template |------> 
                                |   259  |       |     259  |       
                                |      PR|       |        FR|       
                                +--------+       +----------+  
                                 
                                     Figure 3              
         
     6. IANA Considerations 

        The dataRecordsReliability Information Element must be requested 
        from IANA, following the process in [RFC5102]. 
         
         
     7. Security Considerations 

        The same security considerations as for the IPFIX Protocol 
        [RFC5101] apply. 
         
         


      
      
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     8. References 

     8.1. Normative References 

        [RFC2119] S. Bradner, Key words for use in RFCs to Indicate 
                Requirement Levels, BCP 14, RFC 2119, March 1997 
         
        [RFC3758] Stewart, R., Ramalho, M, Xie, Q., Tuexen, M., Conrad, 
                P., "Stream Control Transmission Protocol (SCTP), 
                Partial Reliability Extension", May 2004 
         
        [RFC4960] Stewart, R., Ed., "Stream Control Transmission 
                Protocol", RFC 4960, September 2007. 
      
        [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. 
      
        [PSAMP-TECH] T. Zseby, M. Molina, N. Duffield, S. Niccolini, F. 
                Raspall, "Sampling and Filtering Techniques for IP 
                Packet Selection" draft-ietf-psamp-sample-tech-10.txt, 
                Internet-Draft work in progress, June 2007 
         
        [SCTP-RESET] Stewart, R., Lei, P., Tuexen, M, "Stream Control 
                Transmission Protocol (SCTP) Stream Reset",  
                 draft-stewart-tsvwg-sctpstrrst-00.txt, Internet-Draft 
                work in progress, June 2008 
      
         
     8.2. Informative References 

         
        [RFC3917] Quittek, J., Zseby, T., Claise, B. Zander, S, 
                Requirements for IP Flow Information Export, RFC 3917, 
                October 2004 
         
        [IPFIX-ARCH] Sadasivan, G., Brownlee, N., Claise, B., Quittek, 
                J., "Architecture Model for IP Flow Information Export" 
                draft-ietf-ipfix-architecture-12, Internet-Draft work 
                in progress, September 2006 
         


      
      
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        [IPFIX-AS] Zseby, T., Boschi, E., Brownlee, N., Claise, B., 
                "IPFIX Applicability", draft-ietf-ipfix-as-12.txt, 
                Internet-Draft work in progress, February 2007  
         
        [PSAMP-INFO] T. Dietz, F. Dressler, G. Carle, B. Claise, 
                "Information Model for Packet Sampling Exports", draft-
                ietf-psamp-info-08.txt, Internet-Draft work in 
                progress, February 2008 
         
        [PSAMP-PROTO] Claise, B., Quittek, J., and A. Johnson, "Packet 
                Sampling (PSAMP) Protocol Specifications", draft-ietf-
                psamp-protocol-09, Internet-Draft work in progress, 
                December 2007. 
         
        [PSAMP-FMWK] D. Chiou, B. Claise, N. Duffield, A. Greenberg, M. 
                Grossglauser, P. Marimuthu, J. Rexford, G. Sadasivan,  
                "A Framework for Passive Packet Measurement" draft-
                ietf-psamp-framework-12.txt, Internet-Draft work in 
                progress, June 2007 
         
        [IPFIX-RED-RED] Boschi, E., Mark, L., Claise, B. "Reducing 
                Redundancy in IPFIX and PSAMP Reports", Internet-Draft 
                work in progress, draft-ietf-ipfix-reducing-redundancy-
                04.txt, May 2007 
         
        [PSAMP-MIB] Dietz, T., Claise, B. "Definitions of Managed 
                Objects for Packet Sampling", Internet-Draft work in 
                progress, June 2006 
         

     9. Acknowledgements 

        The authors would like to thank Brian Trammell for his expert 
        feedback, Randall Stewart and Peter Lei for their SCTP-related 
        feedback, and Elisa Boschi for her thorough reading.  
         
         










      
      
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     10. Author's Addresses 

        Benoit Claise 
        Cisco Systems Inc. 
        De Kleetlaan 6a b1 
        Diegem 1813 
        Belgium 
            
        Phone: +32 2 704 5622 
        Email: bclaise@cisco.com 
      
      
        Paul Aitken 
        Cisco Systems (Scotland) Ltd. 
        96 Commercial Quay 
        Commercial Street 
        Edinburgh, EH6 6LX, United Kingdom 
            
        Phone: +44 131 561 3616 
        Email: paitken@cisco.com 
         
         
        Andrew Johnson 
        Cisco Systems (Scotland) Ltd. 
        96 Commercial Quay 
        Commercial Street 
        Edinburgh, EH6 6LX, United Kingdom 
            
        Phone: +44 131 561 3641 
        Email: andrjohn@cisco.com 
         
         
        Gerhard Muenz 
        University of Tuebingen 
        Computer Networks and Internet 
        Sand 13 
        Tuebingen  D-72076 
        DE 
         
        Phone: +49 7071 29-70534 
        Email: muenz@informatik.uni-tuebingen.de 
        URI:   http://net.informatik.uni-tuebingen.de/~muenz 
         




      
      
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     11. Intellectual Property Statement 

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     12. Copyright Statement 

        Copyright (C) The IETF Trust (2008). 
         
        This document is subject to the rights, licenses and 
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     13. Disclaimer  

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