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Versions: 00 01 02 03 04 05 06 07 08 09 RFC 5476

   PSAMP working group
   Internet Draft                                EDITOR:     B. Claise
   draft-ietf-psamp-protocol-02.txt                       Cisco Systems
   Expires: April 2006                                     October 2005
 
 
 
              Packet Sampling (PSAMP) Protocol Specifications
 
 
 Status of this Memo
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   applicable patent or other IPR claims of which he or she is aware
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    This Internet-Draft will expire on April 23, 2006.
 
  Copyright Notice
 
    Copyright (C) The Internet Society (2005).
 
 Abstract
 
   This document specifies the export of packet information from a
   PSAMP Exporting Process to a PSAMP Colleting Process. For export of
   packet information the IP Flow Information eXport (IPFIX) protocol
   is used, as both the IPFIX and PSAMP architecture match very well
   and the means provided by the IPFIX protocol are sufficient. The
 
 
 
 
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   document specifies in detail how the IPFIX protocol is used for
   PSAMP export of packet information.
 
  Conventions used in this document
 
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.
 
  Table of Contents
     1. Points of Discussion........................................3
      1.1 Open Issues................................................3
      1.2 Action Items...............................................4
     2. Introduction................................................5
     3. PSAMP Documents Overview....................................5
     4. Terminology.................................................6
      4.1 IPFIX Terminology..........................................6
      4.2 PSAMP Terminology.........................................10
     4.2.1   Observation Points, Packet Streams and Packet Content11
     4.2.2   Selection Process....................................11
     4.2.3   Reporting Process....................................13
     4.2.4   Measurement Process..................................13
     4.2.5   Exporting Process....................................14
     4.2.6   PSAMP Device.........................................14
     4.2.7   Selection Methods....................................14
      4.3 IPFIX and PSMAP Terminology Comparison....................16
     4.3.1   PSAMP and IPFIX Processes............................16
     4.3.2   Packet Report, Packet Interpretation, and Data Record17
     5. Differences between PSAMP and IPFIX........................17
      5.1 Architecture Point of View................................17
      5.2 Protocol Point of View....................................19
      5.3 Information Model Point of View...........................19
     6. PSAMP Requirements versus the IPFIX Solution...............20
      6.1 IPFIX Solution for the PSAMP Requirements.................20
      6.2 High Level View of the Integration........................22
     7. Using the IPFIX Protocol for PSAMP.........................23
      7.1 Selector ID...............................................23
      7.2 The Associations..........................................23
      7.3 Packet Reports............................................23
     7.3.1   Basic Packet Reports.................................23
     7.3.2   Extended Packet Reports..............................25
      7.4 Report Interpretation.....................................26
     7.4.1   Associations Report Interpretation...................26
     7.4.2   Selector Report Interpretation.......................29
     7.4.2.1  Systematic Count-Based Sampling......................29
     7.4.2.2  Systematic Time-Based Sampling.......................30
     7.4.2.3  Random n-out-of-N Sampling...........................31
     7.4.2.4  Uniform Probabilistic Sampling.......................33
 
 
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     7.4.2.5  Non-uniform Probabilistic Sampling...................33
     7.4.2.6  Non-uniform Flow State Sampling......................33
     7.4.2.7  Match Based Filtering and Router State Filtering.....33
     7.4.2.8  Hash Based Filtering.................................35
     7.4.3   Associations Statistics Report Interpretation........35
     7.4.4   Accuracy Report Interpretation.......................37
     7.4.5   Observation Point Report Interpretation..............37
     8. Security Considerations....................................37
     9. IANA Considerations........................................38
     10. References................................................38
      10.1 Normative References.....................................38
      10.2 Informative References...................................38
     11. Acknowledgments...........................................38
 
 
 1.
    Points of Discussion
 
 1.1
     Open Issues
 
   This section covers the open issues, still to be resolved/updated in
   this draft:
 
   PROTO-01 [PSAMP-FMWK] mentions the optional Export Packets
   compression (see section 8.5) Should we mention this in this
   document?
 
   PROTO-02 From a protocol point of view, there a no differences
   between the Field Match Filtering and the Router State Filtering as
   defined in [PSAMP-TECH]. The only difference concerns the I.E. on
   which we do the filtering... part of the packet in one case, not part
   of the packet in the other case. Proposal: merge the 2 methods in
   [PSAMP-TECH]
 
   PROTO-03 The second open issue is concerned with reporting the
   sequential order of sampling and filtering. => order of the scope.
   We spot a new problem: we could export twice the hash value. How to
   distinguish them? How to know that the hash value 1 corresponds to a
   specific definition specified in an Option Template.
 
   PROTO-04 Should probably have a separate section for the examples?
 
   PROTO-05 Transport protocol: SCTP and/or UDP and/or TCP. Nothing is
   mentioned at this stage. [PSAMP-FMWK] and PSAMP charter specifically
   mention UDP.
 
   PROTO-06 Even if the notion of Associations ID is mentioned in
   [PSAMP-TECH], maybe a term such as SelectionPath or PathID would be
   more appropriate.
 
 
 
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   PROTO-07 Even if [PSAMP-TECH] section 7.1 and 7.2 describes that "The
   ASSOCIATIONS field describes the Observation Point and optionally the
   IPFIX processes to which the packet Selector is associated. Values:
   <STREAM ID, IPFIX Metering process ID, IPFIX Exporting process ID,
   IDs of other associated processes>", we can't see an example where
   the IPFIX process(es) ID would be required. Don't we have enough with
   the list of Selector IDs?
 
   PROTO-08 Instead of sending the input sequence number for each
   selector ID, a counter64 value, associated with every packet, the
   working group should discuss the possibility to send the information
   on regular basis with an option template record. Specifically in the
   case of Composite Selector, we would send multiple times a 64-bit
   counter in each packet.
 
   PROTO-09 "The algorithm specific Information Elements, defining
   configuration parameters for match-based and router state filtering,
   are taken from the full range of available IPFIX Information Elements
   [IPFIX-INFO]". What about the ones from [PSAMP-INFO]? In other words,
   are they I.E.s in [PSAMP-INFO] that we could use for the match-based
   and router state filtering?
 
   PROTO-10 We probably don't need the section 6.2 named "High Level
   view of the integration", as this section was an intermediate step in
   an interim version of the draft. To be discussed.
 
   PROTO-11 Discuss how to implement the accuracy report interpretation
 
   PROTO-12 Discuss how to implement the observation point report
   interpretation (if we need one)
 
   PROTO-13 The solution in this document is based on the fact that
   https://psg.com/lists/psamp/psamp.2005/msg00050.html is taken into
   account. That means: no range for the filtering
 
 1.2
     Action Items
 
   PROTO-101 See EDITOR'S NOTE
 
   PROTO-102 insert double spaces after the end of each sentence.
 
   PROTO-103 Should briefly discuss the fact that PSAMP is OK with IPFIX
   requirements in terms of time (uSec precision)
 
   PROTO-104 Fix the terminology sections, as a last step before
   publication
 
 
 
 
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   PROTO-105 Section 6 about "PSAMP requirements": check if any changes
   with the version 5 of [PSAMP-FMWK]. This draft is based on ietf-
   psamp-framework-04.txt.
 
   PROTO-106 Extend security considerations by a discussion on exported
   Payload. Consider whether [PSAMP-INFO] or [PSAMP-PROTO] or both
   is/are the place(s).
 
   PROTO-107 All the examples in section 7 should contain the
   Information Element ID instead of the Information Element name.
   Example: Option 3 =   samp.PacketSpace
   Corrected Example: Option 3 = 305
 
 2.
   Introduction
 
   The name PSAMP is a contraction of the phrase Packet SAMPling. The
   word "sampling" captures the idea that only a subset of all packets
   passing a network element will be selected for reporting. PSAMP
   selection operations include random selection, deterministic
   selection (filtering), and deterministic approximations to random
   selection (hash-based selection).
 
   The IP Flow information export (IPFIX) protocol specified in [IPFIX-
   PROTO] exports IP traffic information [IPFIX-INFO] observed at
   network devices. This matches the general protocol requirements
   outlined in the PSAMP framework [PSAMP-FMWK]. However, there are some
   architectural differences between IPFIX and PSAMP in the requirements
   for an export protocol. While the IPFIX architecture [IPFIX-ARCH] is
   focused on gathering and exporting IP traffic flow information, the
   focus of the PSAMP framework [PSAMP-FMWK] is on exporting information
   on individual packets. This basic difference and a set of derived
   differences in protocol requirements are outlined in Section 5.
   Despite these differences, the IPFIX protocol is well suited as PSAMP
   protocol. Section 5 specifies how the IPFIX protocol is used for the
   export of packet samples. Required extensions of the IPFIX
   information model are specified in the PSAMP information model
   [PSAMP-INFO].
 
 
 3.
   PSAMP Documents Overview
 
   [PSAMP-FMWK]: "A Framework for Packet Selection and Reporting",
   describes the PSAMP framework for network elements to select subsets
   of packets by statistical and other methods, and to export a stream
   of reports on the selected packets to a collector.
 
 
 
 
 
 
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   [PSAMP-TECH]: "Sampling and Filtering Techniques for IP Packet
   Selection", describes the set of packet selection techniques
   supported by PSAMP.
 
   [PSAMP-PROTO]: "Packet Sampling (PSAMP) Protocol Specifications"
   (this document), specifies the export of packet information from a
   PSAMP Exporting Process to a PSAMP Colleting Process
 
   [PSAMP-INFO]: "Information Model for Packet Sampling Exports" defines
   an information and data model for PSAMP.
 
   [PSAMP-MIB]: "Definitions of Managed Objects for Packet Sampling"
   describes the PSAMP Management Information Base
 
 
 4.
   Terminology
 
   As the IPFIX export protocol is used to export the PSAMP information,
   the relevant IPFIX terminology from [IPFIX-PROTO] is copied over in
   this document. The terminology summary table in section 4.1 gives a
   quick overview of the relationships between the different IPFIX
   terms. The PSAMP terminology defined here is fully consistent with
   all terms listed in [PSAMP-TECH] and [PSAMP-FMWK] but only
   definitions that are only relevant to the PSAMP protocol appear here.
   The section 5.4 applies the PSAMP terminology to the IPFIX protocol
   terminology.
 
 4.1
    IPFIX Terminology
 
   EDITOR'S NOTE: The terminology has been entirely copied over from
   [IPFIX-PROTO]. Before publication, we should evaluate which terms
   should be kept, if not all. The ones required for sure so far are:
   Flow Record, Flow, Information Element, Metering Process, Collector,
   Scope, Set, Template Record, Data Record, Data Set, Template Set,
   Template Record(s), Options Template Set, Options Template Record.
   Note: the IPFIX Exporting Process was not used, as the PSAMP
   Exporting Process is more specific.
 
   Observation Point
 
   An Observation Point is a location in the network where IP packets
   can be observed.  Examples include: a line to which a probe is
   attached, a shared medium, such as an Ethernet-based LAN, a single
   port of a router, or a set of interfaces (physical or logical) of a
   router.
 
   Note that every Observation Point is associated with an Observation
   Domain (defined below), and that one Observation Point may be a
 
 
 
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   superset of several other Observation Points.  For example one
   Observation Point can be an entire line card.  That would be the
   superset of the individual Observation Points at the line card's
   interfaces.
 
   Observation Domain
 
   An Observation Domain is the largest set of Observation Points for
   which Flow information can be aggregated by a Metering Process.
   Each Observation Domain presents itself using a unique ID to the
   Collecting Process to identify the IPFIX Messages it generates.  For
   example, a router line card may be an observation domain if it is
   composed of several interfaces, each of which is an Observation
   Point.  Every Observation Point is associated with an Observation
   Domain.
 
   IP Traffic Flow or Flow
 
   There are several definitions of the term 'flow' being used by the
   Internet community.  Within the context of IPFIX we use the following
   definition:
 
   A Flow is defined as a set of IP packets passing an Observation Point
   in the network during a certain time interval.  All packets belonging
   to a particular Flow have a set of common properties.  Each property
   is defined as the result of applying a function to the values of:
 
      1. one or more packet header field (e.g. destination IP address),
      transport header field (e.g. destination port number), or
      application header field (e.g. RTP header fields [RFC1889])
 
      2. one or more characteristics of the packet itself (e.g. number
      of MPLS labels, etc...)
 
      3. one or more of fields derived from packet treatment (e.g. next
      hop IP address, the output interface, etc...)
 
   A packet is defined to belong to a Flow if it completely satisfies
   all the defined properties of the Flow.
 
   This definition covers the range from a Flow containing all packets
   observed at a network interface to a Flow consisting of just a single
   packet between two applications.  It includes packets selected by a
   sampling mechanism.
 
   Flow Key
 
   Each of the fields which
 
 
 
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   1.  Belong to the packet header (e.g. destination IP address)
   2.  Are a property of the packet itself (e.g. packet length)
   3.  Are derived from packet treatment (e.g. AS number)
   and which are used to define a Flow are termed Flow Keys.
 
   Flow Record
 
   A Flow Record contains information about a specific Flow that was
   observed at an Observation Point.  A Flow Record contains measured
   properties of the Flow (e.g. the total number of bytes for all the
   Flow's packets) and usually characteristic properties of the Flow
   (e.g. source IP address).
 
   Metering Process
 
   The Metering Process generates Flow Records.  Inputs to the process
   are packet headers and characteristics observed at an Observation
   Point, and packet treatment at the Observation Point (for example the
   selected output interface).
 
   The Metering Process consists of a set of functions that includes
   packet header capturing, timestamping, sampling, classifying, and
   maintaining Flow Records.
 
   The maintenance of Flow Records may include creating new records,
   updating existing ones, computing Flow statistics, deriving further
   Flow properties, detecting Flow expiration, passing Flow Records to
   the Exporting Process, and deleting Flow Records.
 
   Exporter
 
   A device which hosts one or more Exporting Processes is termed an
   Exporter.
 
   IPFIX Device
 
   An IPFIX Device hosts at least one Observation Point, a Metering
   Process and an Exporting Process.
 
   Collecting Process
 
   A Collecting Process receives Flow Records from one or more
   Exporting Processes.  The Collecting Process might process or store
   received Flow Records, but such actions are out of scope for this
   document.
 
   Collector
 
 
 
 
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   A device which hosts one or more Collecting Processes is termed a
   Collector.
 
   Template
 
   Template is an ordered sequence of <type, length> pairs, used to
   completely specify the structure and semantics of a particular set of
   information that needs to be communicated from an IPFIX Device to a
   Collector.  Each Template is uniquely identifiable by means of a
   Template ID.
 
   IPFIX Message
 
   An IPFIX Message is a message originating at the Exporting Process
   that carries the IPFIX records of this Exporting Process and whose
   destination is a Collecting Process.  An IPFIX Message is
   encapsulated at the transport layer.
 
   Message Header
 
   The Message Header is the first part of an IPFIX Message, which
   provides basic information about the message such as the IPFIX
   version, length of the message, message sequence number, etc.
 
   Template Record
 
   A Template Record defines the structure and interpretation of fields
   in a Data Record.
 
   Data Record
 
   A Data Record is a record that contains values of the parameters
   corresponding to a Template Record.
 
   Options Template Record
 
   An Options Template Record is a Template Record that defines the
   structure and interpretation of fields in a Data Record, including
   defining how to scope the applicability of the Data Record.
 
   Set
 
   Set is a generic term for a collection of records that have a similar
   structure.  In an IPFIX Message, one or more Sets follow the Message
   Header.
 
   There are three different types of Sets: Template Set, Options
   Template Set, and Data Set.
 
 
 
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   Template Set
 
   A Template Set is a collection of one or more Template Records that
   have been grouped together in an IPFIX Message.
 
   Options Template Set
 
   An Options Template Set is a collection of one or more Options
   Template Records that have been grouped together in an IPFIX Message.
 
   Data Set
 
   A Data Set is one or more Data Records, of the same type, that are
   grouped together in an IPFIX Message.  Each Data Record is previously
   defined by a Template Record or an Options Template Record.
 
   Information Element
 
   An Information Element is a protocol and encoding independent
   description of an attribute which may appear in an IPFIX Record.  The
   IPFIX information model [IPFIX-INFO] defines the base set of
   Information Elements for IPFIX.  The type associated with an
   Information Element indicates constraints on what it may contain and
   also determines the valid encoding mechanisms for use in IPFIX.
 
    +------------------+---------------------------------------------+
    |                  |                 Contents                    |
    |                  +--------------------+------------------------+
    |       Set        |      Template      |         Record         |
    +------------------+--------------------+------------------------+
    |   Data Set       |          /         |     Data Record(s)     |
    +------------------+--------------------+------------------------+
    |   Template Set   | Template Record(s) |           /            |
    +------------------+--------------------+------------------------+
    | Options Template | Options Template   |           /            |
    |       Set        | Record(s)          |                        |
    +------------------+--------------------+------------------------+
 
               Figure A: Terminology Summary Table
 
 4.2
     PSAMP Terminology
 
   EDITOR'S NOTE: The terminology has been entirely copied over from
   [PSAMP-TECH], except for some (almost) similar terms where only the
   IPFIX terms were kept (for example, observation point). Before
   publication, we should evaluate which terms should be kept. The ones
   required for sure so far are: Selector, Composite Selector, Packet
 
 
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   Reports, Packet Interpretation, PSAMP device, Collector, Filtering,
   Sampling. Note that the terms Selector ID and Association ID, coming
   from [PSAMP-FMWK], has been added in the Selection Process section.
 
 
 4.2.1    Observation Points, Packet Streams and Packet Content
 
   Observed Packet Stream
 
   The Observed Packet Stream is the set of all packets observed at the
   Observation Point.
 
   Packet Stream
 
   A packet stream denotes a subset of the Observed Packet Stream that
   flows past some specified point within the measurement process. An
   example of a Packet Stream is the output of the selection process.
 
   Packet Content
 
   The packet content denotes the union of the packet header (which
   includes link layer, network layer and other encapsulation headers)
   and the packet payload.
 
 
 4.2.2   Selection Process
 
   Selection Process
 
   A Selection Process takes the Observed Packet Stream as its input and
   selects a subset of that stream as its output.
 
   Selection State
 
   A Selection Process may maintain state information for use by the
   Selection Process and/or the reporting process. At a given time, the
   Selection State may depend on packets observed at and before that
   time, and other variables. Examples include:
 
       (i)   sequence numbers of packets at the input of Selectors;
 
       (ii)  a timestamp of observation of the packet at the
             Observation Point;
 
       (iii) iterators for pseudorandom number generators;
 
       (iv)  hash values calculated during selection;
 
 
 
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       (v)   indicators of whether the packet was selected by a
             given Selector;
 
   Selection Processes may change portions of the Selection State as a
   result of processing a packet. Selection state for a packet is to
   reflect the state after processing the packet.
 
   Selector
 
   A Selector defines the action of a Selection Process on a single
   packet of its input. If selected, the packet becomes an element of
   the output Packet Stream.
 
   The Selector can make use of the following information in determining
   whether a packet is selected:
 
       (i)  the packet's content;
 
       (ii) information derived from the packet's treatment at the
            Observation Point;
 
       (iii) any selection state that may be maintained by the
             Selection Process.
 
   Composite Selector
 
   A Composite Selector is an ordered composition of Selectors, in which
   the output Packet Stream issuing from one Selector forms the input
   Packet Stream to the succeeding Selector.
 
   Primitive Selector
 
   A Selector is primitive if it is not a Composite Selector.
 
   Selector ID
 
   The Selector ID is the unique ID identifying a Primitive Selector.
 
   Associations ID
 
   From all the packets observed at an Observation Point, only a few
   packets are selected by one or more Selectors. The Associations ID is
   a unique value describing the Observation Point and the Selector IDs
   through which the packets are selected. The Associations ID is
   represented by the associationsID Information Element [PSAMP-INFO].
 
 
 
 
 
 
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 4.2.3   Reporting Process
 
   Reporting Process
 
   A Reporting Process creates a Report Stream on packets selected by a
   Selection Process, in preparation for export.  The input to the
   Reporting Process comprises that information available to the
   Selection Process per selected packet, specifically:
 
       (i)   the selected packet's content;
 
       (ii)  information derived from the selected packet's
             treatment at the Observation Point;
 
       (iii) any Selection State maintained by the inputting
             Selection Process, reflecting any modifications to the
             Selection State made during selection of the packet.
 
   Packet Reports
 
   Packet Reports comprise a configurable subset of a packet's input to
   the reporting process, including the packet's content, information
   relating to its treatment (for example, the output interface), and
   its associated selection state (for example, a hash of the packet's
   content)
 
   Report Interpretation:
 
   Report Interpretation comprises subsidiary information, relating to
   one or more packets, that is used for interpretation of their packet
   reports. Examples include configuration parameters of the Selection
   Process and of the Reporting Process.
 
   Report Stream:
 
   The Report Stream is the output of a Reporting Process, comprising
   two distinguished types of information: Packet Reports, and Report
   Interpretation.
 
 4.2.4   Measurement Process
 
   Measurement Process
 
   A Measurement Process is the composition of a Selection Process that
   takes the Observed Packet Stream as its input, followed by a
   Reporting Process.
 
 
 
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 4.2.5   Exporting Process
 
   Exporting Process:
 
   An Exporting Process sends, in the form of Export Packet, the output
   of one or more Measurement Processes to one or more Collectors.
 
   Export Packet:
 
   An Export Packet is a combination of Report Interpretation and/or one
   or more Packet Reports are bundled by the Exporting Process into a
   Export Packet for exporting to a Collector.
 
 
 4.2.6   PSAMP Device
 
   PSAMP Device
 
   A PSAMP Device is a device hosting at least an Observation Point, a
   Measurement Process and an Exporting Process. Typically,
   corresponding Observation Point(s), Measurement Process(es) and
   Exporting Process(es) are co-located at this device, for example at a
   router.
 
 4.2.7   Selection Methods
 
   Filtering
 
   A filter is a Selector that selects a packet deterministically based
   on the Packet Content, or its treatment, or functions of these
   occurring in the Selection State. Examples include field match
   Filtering, and Hash-based Selection.
 
   Sampling
 
   A Selector that is not a filter is called a Sampling operation. This
   reflects the intuitive notion that if the selection of a packet
   cannot be determined from its content alone, there must be some type
   of Sampling taking place.
 
   Content-independent Sampling
 
   A Sampling operation that does not use Packet Content (or quantities
   derived from it) as the basis for selection is called a Content-
   independent Sampling operation.  Examples include systematic
   Sampling, and uniform pseudorandom Sampling driven by a pseudorandom
   number whose generation is independent of Packet Content. Note that
 
 
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   in Content-independent Sampling it is not necessary to access the
   Packet Content in order to make the selection decision.
 
   Content-dependent Sampling
 
   A Sampling operation where selection is dependent on Packet Content
   is called a Content-dependent Sampling operation.  Examples include
   pseudorandom selection according to a probability that depends on the
   contents of a packet field. Note that this is not a filter, because
   the selection is not deterministic.
 
   Hash Domain
 
   A subset of the Packet Content and the packet treatment, viewed as an
   N-bit string for some positive integer N.
 
   Hash Range
 
   A set of M-bit strings for some positive integer M that define the
   range of values the result of the hash operation can take.
 
   Hash Function
 
   A deterministic map from the Hash Domain into the Hash Range.
 
   Hash Selection Range
 
   A subset of the Hash Range. The packet is selected if the action of
   the Hash Function on the Hash Domain for the packet yields a result
   in the Hash Selection Range.
 
   Hash-based Selection
 
   Filtering specified by a Hash Domain, a Hash Function, and Hash Range
   and a Hash Selection Range.
 
   Approximative Selection
 
   Selectors in any of the above categories may be approximated by
   operations in the same or another category for the purposes of
   implementation. For example, uniform pseudorandom Sampling may be
   approximated by Hash-based Selection, using a suitable Hash Function
   and Hash Domain. In this case, the closeness of the approximation
   depends on the choice of Hash Function and Hash Domain.
 
   Population
 
   A Population is a Packet Stream, or a subset of a Packet Stream. A
   Population can be considered as a base set from which packets are
 
 
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   selected. An example is all packets in the Observed Packet Stream
   that are observed within some specified time interval.
 
   Population Size
 
   The Population Size is the number of all packets in the Population.
 
   Sample Size
 
   The number of packets selected from the Population by a Selector.
 
   Configured Selection Fraction
 
   The Configured Selection Fraction is the ratio of the number of
   packets selected by a Selector from an input Population, to the
   Population Size, as based on the configured selection parameters.
 
   Attained Selection Fraction
 
   The Attained Selection Fraction is the actual ratio of the
   number of packets selected by a Selector from an input
   Population, to the Population Size.
   For some sampling methods the Attained Selection Fraction can differ
   from the Configured Selection Fraction due to, for example, the
   inherent statistical variability in sampling decisions of
   probabilistic Sampling and Hash-based Selection. Nevertheless, for
   large Population Sizes and properly configured Selectors, the
   Attained Selection Fraction usually approaches the Configured
   Selection Fraction.
 
 4.3
     IPFIX and PSMAP Terminology Comparison
 
   EDITOR'S NOTE:
     Some terms between IPFIX and PSAMP were almost similar but not
     quite:
     - observation point. I kept the one from IPFIX. However, if the
     PSAMP/IPFIX definitons would be aligned, it would better.
     - exporting process. I kept the one from PSAMP
     - Collector: I kept the one from IPFIX, which implies that I used
     the Collecting Process defined in IPFIX (it speaks about flows, but
     there is no PSAMP Collecting Process definition)
 
   The PSAMP terminology has been specified with an IPFIX background, as
   PSAMP and IPFIX have similar terms. However, this section explains a
   couple of non compatible terms between IPFIX and PSAMP.
 
 4.3.1   PSAMP and IPFIX Processes
 
 
 
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   The figure B indicates the sequence of the three processes
   (selection, reporting, and exporting) within the PSAMP Device. The
   composition of the Selection Process followed by the Reporting
   Process is known as the Measurement Process.
 
                 +---------+    +---------+    +---------+
       Observed  |Selection|    |Reporting|    |Exporting|
       Packet--->|Process  |--->|Process  |--->|Process  |--->Collector
       Stream    +---------+    +---------+    +---------+
               \----Measurement Process-----/
 
       Figure B: PSAMP Processes
 
   The PSAMP Measurement Process can be viewed as analogous to the IPFIX
   Metering Process. The PSAMP Measurement Process takes an Observed
   Packet Stream as its input, and produces Packet Reports as its
   output. The IPFIX Metering Process produces Flow Records as its
   output. The distinct name "Measurement Process" has been retained in
   PSAMP in order to avoid potential confusion in settings where IPFIX
   and PSAMP coexist, and in order to avoid the implicit requirement
   that the PSAMP version satisfy the requirements of an IPFIX Metering
   Process.
 
 4.3.2   Packet Report, Packet Interpretation, and Data Record
 
   The PSAMP terminology speaks of Packet Report and Packet
   Interpretation, while the IPFIX terminology speaks of Data Record and
   (Option) Template Record. The Packet Report, which comprises
   information about the observed packet, can be viewed as analogous to
   the Data Record defined by a Template Record. The Packet
   Interpretation, which comprises subsidiary information used for the
   interpretation of the packet reports, can be viewed as analogous to
   the Data Record defined by an Option Template Record.
 
 5.
   Differences between PSAMP and IPFIX
 
   The output of the IPFIX working group relevant for this draft is
   structured into three documents:
      - IP Flow information architecture [IPFIX-ARCH]
      - IPFIX Protocol Specifications [IPFIX-PROTO]
      - IP Flow information export information model [IPFIX-INFO]
 
 5.1
     Architecture Point of View
 
   Traffic Flow measurement as described in the IPFIX requirements
   [RFC3917] and the IPFIX architecture [IPFIX-ARCH] can be separated
   into two stages: packet processing and Flow processing.
   The figure C illustrates these stages.
 
 
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   On stage 1, all processing steps act on packets. Packets are
   captured, time stamped, selected by one or more selection steps and
   finally forwarded to packet classification that maps packets to
   Flows. The packets selection steps may include filtering and sampling
   functions.
 
   On stage 2, all processing steps act on Flows. After packets are
   classified (mapped to Flows), Flows are generated, or updated if they
   exist already. Flow generation and update steps may be performed
   repeatedly for aggregating Flows. Finally, Flows are exported.
 
   Packet sampling as described in the PSAMP framework [PSAMP-FMWK]
   covers only stage 1 of the IPFIX architecture with the packet
   classification replaced by packet record export.
 
      IPFIX architecture                       PSAMP framework
 
 
        packet header                           packet header
           capturing     \                         capturing
              |          |                            |
         timestamping    |                       timestamping
              |          |                            |
              v          |                            v
      +------>+          |  stage 1:          +------>+
      |       |           > packet            |       |
      |    packet        |  processing        |    packet
      |   selection      |                    |   selection
      |       |          |                    |       |
      +-------+          |                    +-------+
              |          |                            |
              v          |                            v
           packet       /                       packet record
        classification  \                          export
              |          |
              v          |
      +------>+          |
      |       |          |
      | Flow generation  |
      |   and update     |  stage 2:
      |       |           > Flow
      |       v          |  processing
      |     Flow         |
      |   selection      |
      |       |          |
      +-------+          |
              |          |
              v          |
 
 
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         Flow Record    /
           export
 
       Figure C: Comparison of IPFIX architecture and PSAMP framework
 
 5.2
     Protocol Point of View
 
   Concerning the protocol, the major difference between IPFIX and PSAMP
   is that the IPFIX protocol exports Flow Records while the PSAMP
   protocol exports packet records. 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 special IPFIX Flow Record
   containing information about a single packet.
 
   All extensions of the IPFIX protocol that are required to satisfy the
   PSAMP requirements, have already been incorporated in the IPFIX
   protocol [IPFIX-PROTO], which was developed in parallel with the
   PSAMP protocol. An example is the need of a data type for protocol
   fields that have flexible length, such as an octet array. This was
   added to the IPFIX protocol specification in order to meet the
   requirement of the PSAMP protocol to report content of captured
   packets, for example the first octets of a packet.
 
 5.3
     Information Model Point of View
 
   From the information model point of view, the overlap between both
   the IPFIX and PSAMP protocols is quite large. Most of the data fields
   in the IPFIX protocol are also relevant for exporting packet
   information, for example all fields reporting packet header
   properties. Only a few fields, such as flowCount, packetCount (whose
   value will always be 1 for PSAMP) etc., cannot be used in a
   meaningful way by the PSAMP protocol. Also, IPFIX protocol
   requirements concerning stage 2 of figure C do not apply to the PSAMP
   metering process.
 
   Further required extensions apply to the information model. Even if
   the IPFIX charter speaks of sampling, no sampling related Information
   Elements are specified in [IPFIX-INFO]. The task of specifying them
   was intentionally left for the PSAMP information model. A set of
   several additional fields is required for satisfying the requirements
   for the PSAMP information model [PSAMP-TECH].
 
   Additional required extensions of the information model concern
   packet filtering, and the field reporting content of a packet using
   the flexible length data type mentioned above.
 
 
 
 
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   Exploiting the extensibility of the IPFIX information model, the
   required extension is covered by the PSAMP information model
   specified in [PSAMP-INFO].
 
 6.
   PSAMP Requirements versus the IPFIX Solution
 
   [PSAMP-FMWK] describes some requirements that affect directly the
   export protocol. Refer to the following sections:
     . section 3.2 "Reporting Process Requirements"
     . section 3.3 "Exporting Process Requirements"
     . section 5 "Reporting Process"
 
   [PSAMP-FMWK] also describes in the section 3.1 one requirement that,
   if not directly related to the export protocol, will put some
   constraints on it:
      Selection Process Requirements:
      - Parallel Measurements: multiple independent measurement
   processes at the same entity."
 
   [PSAMP-FMWK] finally describes in the section 5 some requirements
   regarding the reporting process. This series of requirements
   specifies the different Information Elements that MUST and SHOULD
   reported to the Collector. Nevertheless IPFIX, being a generic export
   protocol, can export any Information Elements as long as there are
   described in the information model. So these requirements are mainly
   targeted for the [PSAMP-INFO] document.
 
 6.1
    IPFIX Solution for the PSAMP Requirements
 
   Let's address the PSAMP requirements one by one.
 
   * Parallel Measurements: multiple independent measurement processes
   at the same entity. Refer to [PSAMP-FMWK] section 3.1 "Selection
   Process Requirements".
 
   This requirement is addressed by exporting the Associations ID
   Information Element in every packet report. Note that without this
   requirement, exporting the Selector ID in a Scope part of every
   single packet report could have been sufficient.
 
   * Transparency: allow transparent interpretation of measurements as
   communicated by PSAMP reporting, without any need to obtain
   additional information concerning the observed packet stream. Refer
   to [PSAMP-FMWK] section 3.2 "Reporting Process Requirements".
 
   This requirement is addressed by exporting the Associations ID
   Information Element in every Packet Report (a Data Record specified
   in Template Record) and exporting the associated selection algorithm
 
 
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   and selection parameters Information Elements in the Packet
   Interpretation (a Data Record specified in Options Template Record).
 
   * Robustness to Information Loss: allow robust interpretation of
   measurements with respect to reports missing due to data loss, e.g.
   in transport, or within the measurement, reporting or Exporting
   Processes. Inclusion in reporting of information that enables the
   accuracy of measurements to be determined. Refer to [PSAMP-FMWK]
   section 3.2 "Reporting Process Requirements".
 
   An Options Template, with updated statistics, MUST be sent on regular
   basis. This Options Template contains for example the total number of
   packet report exported from the PSAMP device, the total number of
   packet observed, etc... Thus the Collector can compare the number of
   packet report received per selector ID with the number actually
   metered and/or sent. In case of discrepancy, a new sampling rate
   could be computed.
 
   * Faithfulness: all reported quantities that relate to the packet
   treatment MUST reflect the router state and configuration encountered
   by the packet at the time it is received by the measurement process.
   Refer to [PSAMP-FMWK] section 3.2 "Reporting Process Requirements".
 
   This requirement doesn't concern the export protocol itself but the
   Metering Process, even if described in the "Reporting Process
   Requirements" section.
 
   * Privacy: selection of the content of packet reports will be
   cognizant of privacy and anonymity issues while being responsive to
   the needs of measurement applications, and in accordance with RFC
   2804. Full packet capture of arbitrary packet streams is explicitly
   out of scope. Refer to [PSAMP-FMWK] section 3.2 "Reporting Process
   Requirements".
 
   This requirement doesn't concern the export protocol itself, even if
   described in the "Reporting Process Requirements" section.
 
   * Timeliness: reports on selected packets MUST be made available to
   the Collector quickly enough to support near real time applications.
   Specifically, any report on a packet MUST be dispatched within 1
   second of the time of receipt of the packet by the measurement
   process. Refer to [PSAMP-FMWK] section 3.3 "Export Process
   Requirements".
 
   EDITOR'S NOTE: the term "dispatched" is not clear. Does it mean sent
   from the Metering Processing to the Exporting Process? Or put into a
   packet by the Exporting Process? Or written on the wire?
 
 
 
 
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   The IPFIX protocol specifications [IPFIX-PROTO] describe an
   inactivity timeout for the Flow expiration. This inactivity timeout
   is configurable, with a minimum value of 0 for immediate expiration.
   Note that this minimum value of 0 will force every single Data Record
   to contain information about a single packet and not an aggregation
   of packets.
 
   * Congestion Avoidance: export of a report stream across a network
   MUST be congestion avoiding in compliance with RFC 2914. Refer to
   [PSAMP-FMWK] section 3.3 "Export Process Requirements".
 
   IPFIX, by its charter, MUST also respect this requirement.
 
   * Secure Export:
   - confidentiality: the option to encrypt exported data MUST be
   provided.
   - integrity: alterations in transit to exported data MUST be
   detectable at the Collector
   - authenticity: authenticity of exported data MUST be verifiable by
   the Collector in order to detect forged data.
 
   The motivation here is the same as for security in IPFIX export.
   Refer to [PSAMP-FMWK] section 3.3 "Export Process Requirements".
 
 6.2
    High Level View of the Integration
 
   The Template Record in the Template Set is used to describe the
   different PSAMP Information Elements that will be exported to the
   Collector. The Collector decodes the Template Record in the Template
   Set and knows which Information Elements to expect when it receives
   the Data Records in the Data Set, i.e. the PSAMP Packet Reports.
   Typically, in the base level of the PSAMP functionality, the Template
   Set will contain the input sequence number, the packet fragment (some
   number of contiguous bytes from the start of the packet) and the
   Associations ID.
 
   The Options Template Record in the Options Template Set is used to
   describe the different PSAMP Information Elements that concern the
   Metering Process itself: sampling and/or filtering functions, plus
   the associated parameters. The Collector decodes the Options Template
   Records in the Option Template Set and knows which Information
   Elements to expect when it receives the Data Records in the Data Set,
   i.e. the PSAMP Report Interpretation. Typically, the Options Template
   would contain the Associations ID, the sampling or filtering
   functions, and the sampling or filtering associated parameters.
 
   PSAMP requires all the different possibilities of the IPFIX protocol
   specifications [IPFIX-PROTO]. That is the 3 types of Set (Data Set,
   Template Set and Options Templates Set) with the 2 types of Templates
 
 
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   Records (Template Record and Options Template Record), as described
   in the figure A. As a consequence, PSAMP can't rely on a subset of
   the IPFIX protocol specifications are described in [IPFIX-PROTO]. The
   entire IPFIX protocol specifications [IPFIX-PROTO] MUST be
   implemented for the PSAMP export.
 
 7.
   Using the IPFIX Protocol for PSAMP
 
 7.1
    Selector ID
 
   The Selector ID is the unique ID identifying a Primitive Selector.
   Each Primitive Selector MUST have a unique ID within the Observation
   Domain.
 
 7.2
    The Associations
 
   From all the packets observed at an Observation Point, a subset of
   packets is selected by one or more Selectors. The Associations ID is
   a unique value describing the Observation Point and the Selector IDs
   through which the packets are selected. The Associations ID is
   represented by the associationsId Information Element [PSAMP-INFO].
 
   Optionally, the IPFIX processes to which the packets are MAY be added
   to the Associations ID. Example of IPFIX processes are IPFIX Metering
   Process ID and IPFIX Exporting Process ID.
 
   EDITOR'S NOTE: Even if [PSAMP-TECH] section 7.1 and 7.2 describes
   that "The ASSOCIATIONS field describes the Observation Point and
   optionally the IPFIX processes to which the packet Selector is
   associated. Values: <STREAM ID, IPFIX Metering process ID, IPFIX
   Exporting process ID, IDs of other associated processes>", we can't
   see an example where the IPFIX process(es) ID would be required.
   Don't we have enough with the list of Selector IDs?
 
 7.3
    Packet Reports
 
   For each Assocations, for each select packet, a Packet Report MUST be
   created. The format of the Packet Report is specified in a Template
   Record contained in a Template Set.
 
   There are two types of Packet Report, as described in [PSAMP-FWMK]:
   the basic Packet Report and the extended Packet Report.
 
 7.3.1   Basic Packet Reports
 
   For each selected packet, the Packet Report MUST contain the
   following information:
   - The associationsId Information Element
 
 
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   - Some number of contiguous bytes from the start of the packet,
   including the packet header (which includes link layer, network layer
   and other encapsulation headers) and some subsequent bytes of the
   packet payload. The Layer2PacketSection and ipPacketSection PSAMP
   elements are available for this use.  The Information Element can be
   provided either with a fixed length field or with a variable sized
   field
   - the input sequence number(s) of any Selectors that acted on the
   packet
 
   EDITOR'S NOTE: We should probably list all the possible Information
   Elements from [PSAMP-INFO]: Layer2PacketSection, ipPacketSection,
   etc...
 
   EDITOR'S NOTE: instead of sending the input sequence number for each
   selector ID, a counter64 value, associated with every packet, the
   working group should discuss the possibility to send the information
   on regular basis with an option template record. Specifically in the
   case of Composite Selector, we would send multiple times a 64-bit
   counter in each packet. The example below doesn't contain the input
   sequence number.
 
   Here is an example of a basic Packet Report, with an AssociationsId
   value of 9 (will be explained later on) and a fixed ipPacketSection
   field of 12 bytes:
 
    IPFIX Template 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                  2  |  Length =                 16  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Template ID =           260  |  Field Count =             2  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  IE ID =      AssociationsId  |  IE Length =               4  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  IE ID =     ipPacketSection  |  IE Length =              12  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
    The associated IPFIX 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                260  |  Length =                 20  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: AssociationsId =                                9  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
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   |  Record 1: ipPacketSection =                     0x4500 005B  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  ...continued =                                  0xA174 0000  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  ...continued =                                  0xFF11 832E  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
            Figure D: Example of a Basic Packet Report
 
 
 7.3.2   Extended Packet Reports
 
   Alternatively to the basic Packet Report, the extended Packet Report
   MAY contain extra information related to the protocols used in the
   packet (such as source and destination IP addresses), related to the
   packet treatment (such as output interface, destination BGP
   autonomous system), related to the Selection State associated with
   the packet (such as timestamps, hash values). Using the IPFIX
   Information Elements [IPFIX-INFO], the extra information is added to
   the Template Record.
 
   It is envisaged that selection of fields for Extended Packet
   Reporting may be used to reduce reporting bandwidth, in which case
   the option to report some number of contiguous bytes from the start
   of the packet, mandatory in the basic Packet Report, may not be
   exercised.
 
   Example of a detailed Extended Packet Report:
 
    IPFIX Template 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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Set ID =                    2 |  Length =                 32  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Template ID =             261 |  Field Count =             6  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | IE ID =        associationsId |  IE Length =               4  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | IE ID =     sourceIPv4Address |  IE Length =               4  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | IE ID = destinationIPv4Address|  IE Length =               4  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | IE ID =       totalLengthIPv4 |  IE Length =               2  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | IE ID =         tcpSourcePort |  IE Length =               2  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
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    | IE ID =    tcpDestinationPort |  IE Length =               2  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
    The associated IPFIX 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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Set ID =                261  |  Length =                 20  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Record 1: AssociationsId =                                9  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Record 1: sourceIPv4Address =                      10.0.0.1  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Record 1: destinationIPv4Address =               10.0.1.106  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Rec. 1: totalLengthIPv4 = 72 | Rec. 1: tcpSourcePort =   1372 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  Rec. 1: tcpDestinationPort=80|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure E: Example of an Extended Packet Report
 
 
  7.4
     Report Interpretation
 
   To make full sense of the Packet Reports there are a number of
   additional pieces of information that must be communicated to the
   Collector:
   - The details about which Selectors and Observation Points are being
   used within an Associations MUST be provided using the Associations
   Report Interpretation.
   - The configuration details of each Selector MUST be provided using
   the Selector Report Interpretation.
   - The Selector ID statistics MUST be provided using the
   AssociationsStatistics Report Interpretation.
   - The accuracies of the reported fields MUST be provided using the
   Accuracy Report Interpretation.
   - Further information about each Observation Point MAY be provided
   using the Observation Point Report Interpretation.
 
 
 7.4.1   Associations Report Interpretation
 
   Each Packet Report contains an associationsId Information Element
   that identifies the particular combination of Observation Point and
   Selectors used for its selection.  For every associationsId
   Information Element in use, the PSAMP Device MUST export an
 
 
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   Associations Report Interpretation using an Options Template with the
   following Information Element:
 
    Scope:     associationsId
    Non-Scope: observationPointId
               selectorId (one or more)
 
   If the packets are selected by a Composite Selector, the Associations
   ID field is composed of several Primitive Selectors. In such a case,
   the Associations Report Interpretation MUST contain the list of all
   the Primitive Selector IDs in the Associations ID.  If multiple
   Selectors are contained in the Associations Report Interpretation,
   the Selectors ID MUST be identified in the order they are used.
 
   Optionally, the Associations Report Interpretation MAY contain the
   following Information
    Non-Scope:  meteringProcessId
                exportingProcessId
 
   The observationPointID SHOULD be first Information Element and the
   optional processes SHOULD be last ones so that the path of the
   selected Packet is provided in the logical order.
 
   EDITOR'S NOTE: Even if [PSAMP-TECH] section 7.1 and 7.2 describes
   that "The ASSOCIATIONS field describes the Observation Point and
   optionally the IPFIX processes to which the packet Selector is
   associated. Values: <STREAM ID, IPFIX Metering process ID, IPFIX
   Exporting process ID, IDs of other associated processes>", we can't
   see an example where the IPFIX process(es) ID would be required.
   Don't we have enough with the list of Selector IDs? If we don't need
   the IPFIX Process ID, the following examples must be updated.
 
   Example of a Two Associations ID:
 
    Selection Path 7 (Filter->Sampling):
      observationPointID  1 (Interface 5),
      selectorId          5 (Filter, match IPV4SourceAddress 10.0.0.1),
      selectorId         10 (Sampler, Random 1 out-of ten),
      meteringProcessID    15 (IPFIX Metering Process)
 
    Selection Path 9 (Sampling->Filtering):
      observationPointID  1 (Interface 5),
      selectorId         10 (Sampler, Random 1 out-of ten),
      selectorId          5 (Filter, match IPV4SourceAddress 10.0.0.1),
      meteringProcessID    15 (IPFIX Metering Process)
 
   IPFIX Options Template Record:
 
    0                   1                   2                   3
 
 
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    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                  3  | Length =                   30 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Template ID =           262  | Field Count =               5 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope Field Count =       4  | Scope 1 =      AssociationsId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope 1 Length =          4  | Option 1 = ObservationPointId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 1 Length =         4  | Option 2 =         selectorId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 2 Length =         4  | Option 4 =         selectorId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 3 Length =         4  | Option 5 =  MeteringProcessId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 4 Length =         4  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
   The associated IPFIX 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                262  | Length =                  44  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: AssociationsId =                                7  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: ObservationPointId =                            1  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: selectorId =                                    5  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: selectorId =                                   10  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: MeteringProcessId =                            15  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: AssociationsId =                                9  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: Obs.PointId =                                   1  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: selectorId =                                   10  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: selectorId =                                    5  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: MeteringProcessId =                            15  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure F: Example of an Associations Report Interpretation
 
 
 
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   Notes:
   * There are two Records here in the same Data Set.  Each record
   defines a different Selection Path.
   * If a different Selection Path used three Selectors then a different
   Options Template would have to be used.
 
 7.4.2   Selector Report Interpretation
 
   An IPFIX Data Record, defined by an Option Template Record, MUST be
   used to send the configuration details of every Selector in use. The
   Option Template Record MUST contain the selectorId as the Scope field
   and the SelectorAlgorithm followed by some type specific
   configuration fields as the data:
 
    Scope:     selectorId
    Non-scope: selectorAlgorithm
               algorithm specific Information Elements
 
   The algorithm specific Information Elements are specified in the
   following subsections, depending on the selection method represented
   by the value of the selectorAlgorithm.
 
   The Associations statistics MUST be exported periodically.
 
 7.4.2.1 Systematic Count-Based Sampling
 
   In systematic count-based Sampling, the start and stop triggers for
   the Sampling interval are defined in accordance to the spatial packet
   position (packet count) [PSAMP-TECH].
   The algorithm specific Information Elements in case of systematic
   count-based Sampling are:
 
      samplingPacketInterval: number of packets selected in a row
      samplingPacketSpace:    number of packets between selections
 
   Example of a simple 1 out-of 10 systematic count-based Selector
   definition, where the samplingPacketInterval is 1 and the
   samplingPacketSpace is 9.
 
   IPFIX Options Template 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                  3  | Length =                   26 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
   |  Template ID =           263  | Field Count =               4 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope Field Count =       1  | Scope 1 =          selectorId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope 1 Length =          4  | Option 1 =  selectorAlgorithm |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 1 Length =         1  | Option 2 = samp.Pack.Interval |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 2 Length =         1  | Option 3 =   samp.PacketSpace |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 3 Length =         1  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
   Associated IPFIX 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Set ID =                 263  |  Length =                 11  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | selectorId (scope) =                                      15  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | .Algorithm= 1 | .Interval=  1 |   .Space = 09 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure G: Example of the Selector Report Interpretation,
                 For Systematic Count-Based Sampling
 
   Notes:
   * A samplingAlgorithm value of 1 represents systematic count-based
   Sampling.
   * samplingPacketInterval and samplingPacketSpace are of type
   unsigned32 but are compressed down to one octet here.
 
 
 7.4.2.2 Systematic Time-Based Sampling
 
   In systematic time-based Sampling, the start and stop triggers are
   used to define the Sampling intervals [PSAMP-TECH]. The algorithm
   specific Information Elements in case of systematic time-based
   Sampling are:
 
      samplingTimeInterval: time (in ms) when packets are selected
      samplingTimeSpace:    time (in ms) between selections
 
   Example of a 100 ms out-of 1000 ms systematic time-based Selector
   definition, where the samplingTimeInterval is 100 and the
 
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
   samplingTimeSpace is 900
 
   IPFIX Options Template 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                  3  | Length =                   26 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Template ID =           264  | Field Count =               4 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope Field Count =       1  | Scope 1 =          selectorId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope 1 Length =          4  | Option 1 =  selectorAlgorithm |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 1 Length =         1  | Option 2 =  samp.TimeInterval |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 2 Length =         1  | Option 3 =     samp.TimeSpace |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 3 Length =         2  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
   Associated IPFIX 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Set ID =                 264  |  Length =                 16  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | selectorId (scope) =                                      16  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | .Algorithm= 2 | .Interval=100 | samplingTimeSpace =       900 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure H: Example of the Selector Report Interpretation,
                 For Systematic Time-Based Sampling
 
   Notes:
   * A samplingAlgorithm value of 2 represents systematic time-based
   Sampling.
   * samplingTimeInterval and samplingTimeSpace are of type unsigned32
   but are compressed down here.
 
 
 7.4.2.3 Random n-out-of-N Sampling
 
   In random n-out-of-N Sampling, n elements are selected out of the
   parent population that consists of N elements [PSAMP-TECH]. The
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
   algorithm specific Information Elements in case of random n-out-of-N
   Sampling are:
 
      samplingSize:       number of packets selected
      samplingPopulation: number of packets in selection population
 
   Example of a 1 out-of 10 random n-out-of-N sampling Selector:
 
   IPFIX Options Template 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                  3  | Length =                   26 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Template ID =           265  | Field Count =               4 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope Field Count =       1  | Scope 1 =          selectorId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope 1 Length =          4  | Option 1 =  selectorAlgorithm |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 1 Length =         1  | Option 2 =       samplingSize |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 2 Length =         1  | Option 3 = samplingPopulation |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 3 Length =         1  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
   Associated IPFIX 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Set ID =                 265  |  Length =                 11  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | selectorId (scope) =                                      17  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | .Algorithm= 1 | .samp.Size= 1 | samp.Pop = 10 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure I: Example of the Selector Report Interpretation,
                 For Random n-out-of-N Sampling
 
 
   Notes:
   * A samplingAlgorithm value of 3 represents Random n-out-of-N
   sampling.
   * samplingSize and samplingPopulation are of type unsigned32 but are
   compressed down to one octet here.
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
 7.4.2.4 Uniform Probabilistic Sampling
 
   EDITOR'S NOTE: to be completed
 
 7.4.2.5 Non-uniform Probabilistic Sampling
 
   EDITOR'S NOTE: to be completed
 
 7.4.2.6 Non-uniform Flow State Sampling
 
   EDITOR'S NOTE: to be completed
 
 7.4.2.7 Match Based Filtering and Router State Filtering
 
   This classification includes match(es) on field(s) within a packet
   and match(es) on properties of the router state. With this method, a
   packet is selected if a specific field in the packet equals a
   predefined value.
 
   The algorithm specific Information Elements, defining configuration
   parameters for match-based and router state filtering, are taken from
   the full range of available IPFIX Information Elements [IPFIX-INFO].
   Further Information Elements MAY be defined by proprietary
   Information Elements [IPFIX-PROTO]
 
   When multiple different Information Elements are defined, the filter
   acts as a logical AND. Note that the logical OR is not covered by
   these PSAMP specifications. The match based filtering and router
   state filtering Options Template Record MUST NOT have multiple
   identical Information Elements. The result of the filter is
   independent from the order of the Information Elements in the Option
   Template Record, but the order may be important for implementation
   purposes, as the first filter will have to work at a higher rate. In
   any case, an implementation is not constrained to respect the filter
   ordering, as long as the result is the same, and it may even
   implement the composite filtering in filtering in one single step.
 
   EDITOR'S NOTE: "The algorithm specific Information Elements, defining
   configuration parameters for match-based and router state filtering,
   are taken from the full range of available IPFIX Information Elements
   [IPFIX-INFO] ". What about the ones from [PSAMP-INFO]? In other
   words, are they I.E.s in [PSAMP-INFO] that we could use for the
   match-based and router state filtering?
 
   Example of a match based filter Selector, whose rules are:
      IPv4 Source Address   = 10.0.0.1
 
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
      IPv4 Next-Hop Address = 10.0.1.1
 
   IPFIX Options Template 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                  3  | Length =                   26 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Template ID =           266  | Field Count =               4 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope Field Count =       1  | Scope 1 =          selectorId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope 1 Length =          4  | Option 1 =  selectorAlgorithm |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 1 Length =         1  | Option 2 =  sourceIPv4Address |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 2 Length =         4  | Option 3 =ipNextHopIPv4Address|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 3 Length =         4  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
    Associated IPFIX 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Set ID =                 266  |  Length =                 11  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | selectorId (scope) =                                      21  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | .Algorithm= 1 | sourceIPv4Address                = 10.0.0 ... |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | ... .1        | ipNextHopIPv4Address             = 10.0.1 ... |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | ... .1        |
   +-+-+-+-+-+-+-+-+
 
       Figure J: Example of the Selector Report Interpretation,
                 For match based and router state Filtering
 
   Notes:
   * A samplingAlgorithm value of 7 represents match based filtering.
   * In this filter there is a mix of information from the packet and
   information from the router.
 
 
 
 
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
 7.4.2.8 Hash Based Filtering
 
   EDITOR'S NOTE: to be completed
 
 7.4.3   Associations Statistics Report Interpretation
 
   A Selector MAY be used in multiple Associations. However, each use of
   a Selector must be independent, so each separate logical instances of
   a Selector MUST maintain its separate Selection State and statistics.
 
   The Associations Statistics Report Interpretation MUST include the
   number of packets seen (Population Size) and the number of packets
   selected (Sample Size) by each instance of its Primitive Selector.
   Within an Association composed of several Primitive Selectors, the
   number of packets selected for one Selector is equal to the number of
   packets seen by the next Selector. The order of the Selectors in the
   Associations Statistics Report Interpretation MUST match the order of
   the Selectors in the Association, as defined in the Associations
   Report Interpretation.
 
   The Associations Statistics Report Interpretation MUST also contain
   the number of packets observed at the Observation.
 
   For every Associations ID, the PSAMP Device MUST export an
   Associations statistics Report Interpretation using an Options
   Template with the following Information Element:
 
    Scope:     AssociationsId
    Non-scope: packetsObserved
               packetsSelected (one or more)
 
   The packetsObserved Information Element contains the number of
   packets seen at the Observation Point, and as a consequence passed to
   the first Selector in the Association. The packetsSelected
   Information Element contains the number of packets selected by the
   various Selectors in the Associations.
 
   The Attained Selection Fraction can be calculated for each Selector
   by dividing the number of packets selected for that Selector by the
   previous value.
 
   The statistics for the whole sequence SHOULD be taken at a single
   logical point in time, the input value for a Selector MUST equal the
   output value of the previous selector.
 
   Example of Associations Statistics Report Interpretation:
 
    Associations set 7 (Filter->Sampling):
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
 
      Observed   100  (observationPointID  1, Interface 5)
      Selected    50  (selectorId  5, match IPV4SourceAddress 10.0.0.1)
      Selected     6  (selectorId 10, Sampler: Random one out-of ten)
 
    Associations set 9 (Sampling->Filtering):
 
      Observed   100  (observationPointID  1, Interface 5)
      Selected    10  (selectorId 10, Sampler: Random one out-of ten)
      Selected     3  (selectorId  5, match IPV4SourceAddress 10.0.0.1)
 
 
   IPFIX Options Template 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                  3  | Length =                   30 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Template ID =           267  | Field Count =               5 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope Field Count =       1  | Scope 1 =      AssociationsId |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Scope 1 Length =          4  | Option 1 =    packetsObserved |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 1 Length =         4  | Option 2 =    packetsSelected |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 2 Length =         4  | Option 4 =    packetsSelected |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 3 Length =         4  | Option 5 =    packetsSelected |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Option 4 Length =         4  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
   The associate IPFIX 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Set ID =                267  | Length =                  24  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: AssociationsId =                                7  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: packetsObserved  =                            100  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: packetsSelected =                              50  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 1: packetsSelected =                               6  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
   |  Record 2: AssociationsId =                                9  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: packetsObserved  =                            100  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: packetsSelected =                              10  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Record 2: packetsSelected =                               3  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure K: Example of the Association Statistics Report
                 Interpretation
 
   Notes:
   * The Attained Packet Fractions for the first set of Associations
   are:
            Filter 10: 50/100
            Sampler 5: 6/50
            Number of samples sent to Metering Process: 6
   * The Attained Packet Fractions for the second set of Associations
   are:
            Sampler 5: 10/100
            Filter 10: 3/10
            Number of samples sent to Metering Process: 3
 
 
 7.4.4   Accuracy Report Interpretation
 
 
 
 
 
   The inherent accuracy of the Information Elements in the Packet
   Report MUST be reported in order to enable the Collector to determine
   the accuracy of the measurements.
 
   EDITOR'S NOTE: to be completed
 
 
 7.4.5   Observation Point Report Interpretation
 
   For each Observation Point, an Observation Option Report
   Interpretation MAY be sent.
 
   EDITOR'S NOTE: to be completed
 
 8.
   Security Considerations
 
   As IPFIX has been selected as the PSAMP export protocol and as the
   PSAMP security requirements are not stricter than the IPFIX security
   requirements, refer to the IPFIX export protocol [IPFIX-PROTO] for
   the security considerations.
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
 
 9.
   IANA Considerations
 
   The only IANA considerations in this document concern the extension
   of Information Elements, Set ID and Scope. Refer to the IANA
   considerations section in [IPFIX-PROTO] where those possible new
   assignments are specified.
 
 10.
    References
 
 10.1
      Normative References
 
   [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-07.txt
 
   [PSAMP-MIB] T. Dietz, B. Claise "Definitions of Managed Objects for
   Packet Sampling" draft-ietf-psamp-mib-04.txt
 
   [PSAMP-INFO] T. Dietz, F. Dressler, G. Carle, B. Claise, "Information
   Model for Packet Sampling Exports", draft-ietf-psamp-info-02.txt
 
   [IPFIX-ARCH] G. Sadasivan, N. Brownlee, B. Claise, J. Quittek,
   "Architecture Model for IP Flow Information Export" draft-ietf-ipfix-
   arch-08.txt"
 
   [IPFIX-INFO] J. Quittek, S. Bryant, B. Claise, J. Meyer, "Information
   Model for IP Flow Information Export" draft-ietf-ipfix-info-11
 
   [IPFIX-PROTO] B. Claise (Editor) "IPFIX Protocol Specifications",
   draft-ietf-ipfix-protocol-19.txt
 
   [RFC1771]   Y. Rekhter, T. Li, "A Border Gateway Protocol 4 (BGP-4)",
   RFC 1771, March 1995.
 
 10.2
     Informative References
 
   [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-10.txt
 
   [RFC3917] J. Quittek, T. Zseby, B. Claise, S. Zander, "Requirements
   for IP Flow Information Export", RFC 3917, October 2004
 
 11.
    Acknowledgments
 
   The authors would like to thank the PSAMP group, especially Paul
   Aitken for fruitful discussions and for proofreading the document.
 
 
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                  PSAMP Protocol Specifications           October 2005
 
 
 
   Authors' Addresses
 
   Benoit Claise
   Cisco Systems
   De Kleetlaan 6a b1
   1831 Diegem
   Belgium
   Phone: +32 2 704 5622
   E-mail: bclaise@cisco.com
 
   Juergen Quittek
   NEC Europe Ltd.
   Network Laboratories
   Kurfuersten-Anlage 36
   69115 Heidelberg
   Germany
   Phone: +49 6221 90511-15
   Email: quittek@ccrle.nec.de
 
   Andrew Johnson
   Cisco Systems
   96 Commercial Quay
   Edinburgh EH6 6LX
   Scotland
   Phone: +44 131 561 3641
   Email: andrjohn@cisco.com
 
 
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   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
 
 
 Claise, et. al            Standard Track                   [Page 39]
 

                  PSAMP Protocol Specifications           October 2005
 
 
   rights that may cover technology that may be required to implement
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   Copyright Statement
 
   Copyright (C) The Internet Society (2005).  This document is subject
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   Acknowledgment
 
   Funding for the RFC Editor function is currently provided by the
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 Claise, et. al            Standard Track                   [Page 40]
 

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