[IPFIX] review of draft-ietf-ipfix-mediation-protocol-04

[Paul Aitken <[e-mail]>]

Dear Authors,

Here's another review of draft-ietf-ipfix-mediation-protocol-04.

Overall I'm happy with the shape of this draft; I have no major 
technical issues. Just some minor ones, and loads of editorial issues.

Please find comments inline:


>
> IPFIX Working Group                                            B. Claise
> Internet-Draft                                       Cisco Systems, Inc.
> Intended status: Standards Track                            A. Kobayashi
> Expires: August 29, 2013                                             NTT
>                                                               B. Trammell
>                                                                ETH Zurich
>                                                         February 25, 2013
>
>
>   Operation of the IP Flow Information Export (IPFIX) Protocol on IPFIX
>                                 Mediators
>                 draft-ietf-ipfix-mediation-protocol-04.txt
>
> Abstract
>
>     This document specifies the operation of the IP Flow Information
>     Export (IPFIX) protocol specific to IPFIX Mediators, including
>     Template and Observation Point management, timing considerations, and
>     other Mediator-specific concerns.
>
> Status of this Memo
>
>     This Internet-Draft is submitted in full conformance with the
>     provisions of BCP 78 and BCP 79.
>
>     Internet-Drafts are working documents of the Internet Engineering
>     Task Force (IETF).  Note that other groups may also distribute
>     working documents as Internet-Drafts.  The list of current Internet-
>     Drafts is at http://datatracker.ietf.org/drafts/current/.
>
>     Internet-Drafts are draft documents valid for a maximum of six months
>     and may be updated, replaced, or obsoleted by other documents at any
>     time.  It is inappropriate to use Internet-Drafts as reference
>     material or to cite them other than as "work in progress."
>
>     This Internet-Draft will expire on August 29, 2013.
>
> Copyright Notice
>
>     Copyright (c) 2013 IETF Trust and the persons identified as the
>     document authors.  All rights reserved.
>
>     This document is subject to BCP 78 and the IETF Trust's Legal
>     Provisions Relating to IETF Documents
>     (http://trustee.ietf.org/license-info) in effect on the date of
>     publication of this document.  Please review these documents
>     carefully, as they describe your rights and restrictions with respect
>     to this document.  Code Components extracted from this document must
>
>
>
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>     include Simplified BSD License text as described in Section 4.e of
>     the Trust Legal Provisions and are provided without warranty as
>     described in the Simplified BSD License.
>
>
> Table of Contents
>
>     1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
>       1.1.  IPFIX Documents Overview . . . . . . . . . . . . . . . . .  3
>       1.2.  IPFIX Mediator Documents Overview  . . . . . . . . . . . .  4
>       1.3.  Relationship with the IPFIX and PSAMP Protocols  . . . . .  5
>     2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
>     3.  Handling IPFIX Message Headers . . . . . . . . . . . . . . . .  8
>     4.  Template Management  . . . . . . . . . . . . . . . . . . . . . 10
>       4.1.  Passing Unmodified Templates through an IPFIX Mediator . . 11
>         4.1.1.  Template Mapping and Information Element Ordering  . . 14
>       4.2.  Creating New Templates at an IPFIX Mediator  . . . . . . . 15
>       4.3.  Handling Unknown Information Elements  . . . . . . . . . . 16
>     5.  Preserving Original Observation Point Information  . . . . . . 16
>       5.1.  originalExporterIPv4Address Information Element  . . . . . 18
>       5.2.  originalExporterIPv6Address Information Element  . . . . . 18
>     6.  Managing Observation Domain IDs  . . . . . . . . . . . . . . . 19
>       6.1.  originalObservationDomainId Information Element  . . . . . 19
>     7.  Timing Considerations  . . . . . . . . . . . . . . . . . . . . 20
>     8.  Transport Considerations . . . . . . . . . . . . . . . . . . . 21
>     9.  Collecting Process Considerations  . . . . . . . . . . . . . . 21
>     10. Specific Reporting Requirements  . . . . . . . . . . . . . . . 22
>       10.1. Intermediate Process Reliability Statistics Template . . . 22
>       10.2. Flow Key Options Template  . . . . . . . . . . . . . . . . 23
>       10.3. intermediateProcessId Information Element  . . . . . . . . 24
>       10.4. ignoredRecordTotalCount Information Element  . . . . . . . 24
>     11. Configuration Management . . . . . . . . . . . . . . . . . . . 24
>     12. Security Considerations  . . . . . . . . . . . . . . . . . . . 25
>     13. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 25
>     14. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 25
>     15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
>       15.1. Normative References . . . . . . . . . . . . . . . . . . . 26
>       15.2. Informative References . . . . . . . . . . . . . . . . . . 27
>     Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28
>
>
>
>
>
>
>
>
>
>
>
>
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> 1.  Introduction
>
>     The IPFIX architectural components in [RFC5470] consist of IPFIX
>     Devices and IPFIX Collectors communicating using the IPFIX protocol
>     [I-D.ietf-ipfix-protocol-rfc5101bis], which specifies how to export
>     IP Flow information.  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
>     [I-D.ietf-ipfix-information-model-rfc5102bis], registered with IANA,
>     or specified as an enterprise-specific Information Element.  The
>     specifications in the IPFIX protocol
>     [I-D.ietf-ipfix-protocol-rfc5101bis] have not been defined in the
>     context of an IPFIX Mediator receiving, aggregating, correlating,
>     anonymizing, etc...  Flow Records from the one or multiple Exporters.
>     Indeed, the IPFIX protocol must be adapted for Intermediate
>     Processes, as defined in the IPFIX Mediation Reference Model as
>     specified in Figure A of [RFC6183], which is based on the IPFIX
>     Mediation Problem Statement [RFC5982].
>
>     This document specifies the IP Flow Information Export (IPFIX)
>     protocol in the context of the implementation and deployment of IPFIX
>     Mediators.  The use of the IPFIX protocol within an IPFIX Mediator --
>     a device which contains both a Collecting Process and an Exporting
>     Process -- has an impact on the technical details of the usage of the
>     protocol.  An overview of the technical problem is covered in section
>     6 of [RFC5982]: loss of original Exporter information, loss of base
>     time information, transport sessions management, loss of Options
>     Template Information, Template Id management, considerations for
>     network considerations for aggregation.
>
>     The specifications in this document are based on the IPFIX protocol
>     specifications [I-D.ietf-ipfix-protocol-rfc5101bis] but adapted
>     according to the IPFIX Mediation Framework [RFC6183].
>
> 1.1.  IPFIX Documents Overview
>
>     The IPFIX Protocol [I-D.ietf-ipfix-protocol-rfc5101bis] provides
>     network administrators with access to IP Flow information.
>
>     The architecture for the export of measured IP Flow information out
>     of an IPFIX Exporting Process to a Collecting Process is defined in
>     the IPFIX Architecture [RFC5470], per the requirements defined in the
>     IPFIX Requirement doc, [RFC3917].
>
>
>
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>
>     The IPFIX Architecture [RFC5470] specifies how IPFIX Data Records and
>     Templates are carried via a congestion-aware transport protocol from
>     IPFIX Exporting Processes to IPFIX Collecting Processes.
>
>     IPFIX has a formal description of IPFIX Information Elements, their
>     name, type and additional semantic information, as specified in the
>     IPFIX Information Model
>     [I-D.ietf-ipfix-information-model-rfc5102bis].  The registry is
>     maintained by IANA [IPFIX-IANA].  New Information Element definitions
>     can be added to this registry subject to an Expert Review [RFC5226],
>     with additional process considerationsdecribed  in [IPFIX-IE-

Typo, "described".


>     DOCTORS]; that document also provides guidelines for authors and
>     reviewers of new Information Element definitions.  The inline export
>     of the Information Element type information is specified in
>     [RFC5610].
>
>     The IPFIX Applicability Statement [RFC5472] 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.  IPFIX Mediator Documents Overview
>
>     The "IPFIX Mediation: Problem Statement" [RFC5982] provides an
>     overview of the applicability of IPFIX Mediators, and defines
>     requirements for IPFIX Mediators in general terms.  This document is
>     of use largely to define the problems to be solved through the
>     deployment of IPFIX Mediators, and to provide scope to the role of
>     IPFIX Mediators within an IPFIX collection infrastructure.
>
>     The "IPFIX Mediation: Framework" [RFC6183], which details the IPFIX
>     Mediation reference model and the components of an IPFIX Mediator,
>     provides more architectural details of the arrangement of
>     Intermediate Processes within an IPFIX Mediator.
>
>     Documents specifying the operations of specific Intermediate
>     Processes cover the operation of these Processes within the IPFIX
>     Mediator framework, and comply with the specifications given in this
>     document; they may additionally specify the operation of the process
>     independently, outside the context of an IPFIX Mediator, when this is
>     appropriate.  The details of specific Intermediate Processes, when
>     these have additional export specifications (e.g., metadata about the
>     intermediate processing conveyed through IPFIX Options Templates),
>     are each treated in their own document.  As of today, these documents
>     are:
>
>     1.  "IP Flow Anonymization Support", [RFC6235], which describes
>         Anonymization techniques for IP flow data and the export of
>
>
>
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>
>         Anonymized data using the IPFIX protocol.
>
>     2.  "Flow Selection Techniques" [I-D.ietf-ipfix-flow-selection-tech],
>         which describes the process of selecting a subset of Flows from
>         all Flows observed at an Observation Point, the flow selection
>         motivations, and some specific flow selection techniques.
>
>     3.  "Exporting Aggregated Flow Data using IP Flow Information Export"
>         [I-D.ietf-ipfix-a9n] which describes Aggregated Flow export
>         within the framework of IPFIX Mediators and defines an
>         interoperable, implementation-independent method for Aggregated
>         Flow export.
>
>     This document specifies the IP Flow Information Export (IPFIX)
>     protocol specific to Mediation, i.e. the specifications that all
>     Intermediate Processes type must comply to.  Some extra
>     specifications might be required per Intermediate Process type (In
>     which case, the Intermediate Process specific document would cover
>     those).
>
> 1.3.  Relationship with the IPFIX and PSAMP Protocols
>
>     The specification in this document applies to the IPFIX protocol
>     specifications [I-D.ietf-ipfix-protocol-rfc5101bis].  All
>     specifications from [I-D.ietf-ipfix-protocol-rfc5101bis] apply unless
>     specified otherwise in this document.
>
>     As the Packet Sampling (PSAMP) protocol specifications [RFC5476] are
>     based on the IPFIX protocol specifications, the specifications in
>     this document are also valid for the PSAMP protocol.  Therefore, the
>     method specified by this document also applies to PSAMP.
>
>
> 2.  Terminology
>
>     IPFIX-specific terms, such as Observation Domain, Flow, Flow Key,
>     Metering Process, Exporting Process, Exporter, IPFIX Device,
>     Collecting Process, Collector, Template, IPFIX Message, Message
>     Header, Template Record, Data Record, Options Template Record, Set,
>     Data Set, Information Element, Scope and Transport Session, used in
>     this document are defined in [I-D.ietf-ipfix-protocol-rfc5101bis].
>     The PSAMP-specific terms used in this document, such as Filtering and
>     Sampling, are defined in [RFC5476].
>
>     IPFIX Mediation terms related to aggregation, such as the Interval,
>     Aggregated Flow, and Aggregated Function are defined in
>     [I-D.ietf-ipfix-a9n].
>
>
>
>
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>
>     The IPFIX Mediation-specific terminology used in this document is
>     defined in "IPFIX Mediation: Problem Statement" [RFC5982], and reused
>     in "IPFIX Mediation: Framework" [RFC6183].  However, since both of
>     those documents are an informational RFCs, the definitions have been
>     reproduced here along with additional definitions.
>
>     Similarly, since [RFC6235] is an experimental RFC, the Anonymization
>     Record, Anonymized Data Record, and Intermediate Anonymization
>     Process terms, specified in [RFC6235], are also reproduced here.
>
>     In this document, as in [I-D.ietf-ipfix-protocol-rfc5101bis],
>     [RFC5476], [I-D.ietf-ipfix-a9n], and [RFC6235], the first letter of
>     each IPFIX-specific and PSAMP-specific term is capitalized along with
>     the IPFIX Mediation-specific term defined here.
>
>     In this document, we call a stream of records carrying flow- or
>     packet-based information a "record stream".  The records may be
>     encoded as IPFIX Data Recordsof  any other format.

Typo, "or".


>
>     Transport Session Information:   The Transport Session is specified
>        in [I-D.ietf-ipfix-protocol-rfc5101bis].  In SCTP, the Transport
>        Session Information is the SCTP association.  In TCP and UDP, the
>        Transport Session Information corresponds to a 5-tuple {Exporter
>        IP address, Collector IP address, Exporter transport port,
>        Collector transport port, transport protocol}.
>
>     Original Exporter:   An Original Exporter is an IPFIX Device that
>        hosts the Observation Points where the metered IP packets are
>        observed.
>
>     Original Observation Point:   An Observation Point of the Original
>        Exporter.  In the case of the Intermediate Aggregation Process on

These definitions imply that OPs belong to the exporter, which is not 
the case; they belong to the MP or to the IPFIX device.


>        an IPFIX Mediator, the Original Observation Point can be composed
>        of, but not limited to, a (set of) specific Exporter(s), a (set
>        of) specific interface(s) on an Exporter, a (set of) line card(s)
>        on an Exporter, or any combinations of these.
>
>     IPFIX Mediation:   IPFIX Mediation is the manipulation and conversion
>        of a record stream for subsequent export using the IPFIX protocol.
>
>     Template Mapping:   A mapping from Template Records and/or Options
>        Template Records received by an IPFIX Mediator to Template Records
>        and/or Options Template Records sent by that IPFIX Mediator.  Each
>        entry in a Template Mapping is scoped by incoming or outgoing
>        Transport Session and Observation Domain, as with Templates and
>        Options Templates in the IPFIX Protocol.
>
>
>
>
>
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>
>     Anonymization Record:   A record that defines the properties of the
>        anonymization applied to a single Information Element within a
>        single Template or Options Template, as in [RFC6235].
>
>     Anonymized Data Record:   A Data Record within a Data Set containing
>        at least one Information Element with Anonymized values.  The
>        Information Element(s) within the Template or Options Template
>        describing this Data Record SHOULD have a corresponding
>        Anonymization Record, as in [RFC6235].
>
>     The following terms are used in this document to describe the
>     architectural entities used by IPFIX Mediation.
>
>     Intermediate Process:   An Intermediate Process takes a record stream
>        as its input from Collecting Processes, Metering Processes, IPFIX
>        File Readers, other Intermediate Processes, or other record
>        sources; performs some transformations on this stream, based upon
>        the content of each record, states maintained across multiple
>        records, or other data sources; and passes the transformed record
>        stream as its output to Exporting Processes, IPFIX File Writers,
>        or other Intermediate Processes, in order to perform IPFIX
>        Mediation.  Typically, an Intermediate Process is hosted by an
>        IPFIX Mediator.  Alternatively, an Intermediate Process may be
>        hosted by an Original Exporter.
>
>     IPFIX Mediator:   An IPFIX Mediator is an IPFIX Device that provides
>        IPFIX Mediation by receiving a record stream from some data
>        sources, hosting one or more Intermediate Processes to transform
>        that stream, and exporting the transformed record stream into
>        IPFIX Messages via an Exporting Process.  In the common case, an
>        IPFIX Mediator receives a record stream from a Collecting Process,
>        but it could also receive a record stream from data sources not
>        encoded using IPFIX, e.g., in the case of conversion from the
>        NetFlow V9 protocol [RFC3954] to IPFIX protocol.
>
>     Specific Intermediate Processes are described below.
>
>     Intermediate Conversion Process  (as in [RFC6183]): An Intermediate
>        Conversion Process is an Intermediate Process that transforms non-
>        IPFIX into IPFIX or manages the relation among Templates and
>        states of incoming/outgoing transport sessions in the case of
>        transport protocol conversion (e.g., from UDP to SCTP).
>
>     Intermediate Aggregation Process  (as in [I-D.ietf-ipfix-a9n]): an
>        Intermediate Process (IAP) as in [RFC6183] that aggregates
>        records, based upon a set of Flow Keys or functions applied to
>        fields from the record.
>
>
>
>
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>     Intermediate Correlation Process  (as in [RFC6183]): An Intermediate
>        Correlation Process is an Intermediate Process that adds
>        information to records, noting correlations among them, or
>        generates new records with correlated data from multiple records
>        (e.g., the production of bidirectional flow records from
>        unidirectional flow records).
>
>     Intermediate Anonymization Process  (as in [RFC6235]): An
>        intermediate process that takes Data Records and transforms them
>        into Anonymized Data Records.
>
>     Intermediate Selection Process  (as in [RFC6183]): An Intermediate
>        Selection Process is an Intermediate Process that selects records
>        from a sequence based upon criteria-evaluated record values and
>        passes only those records that match the criteria (e.g., Filtering
>        only records from a given network to a given Collector).
>
>     Intermediate Flow Selection Process  (as in
>        [I-D.ietf-ipfix-flow-selection-tech]: An Intermediate Flow
>        Selection Process is an Intermediate Process as in [RFC6183] that
>        takes Flow Records as its input and selects a subset of this set
>        as its output.  Intermediate Flow Selection Process is a more
>        general concept than Intermediate Selection Process as defined in
>        [RFC6183].  While an Intermediate Selection Process selects Flow
>        Records from a sequence based upon criteria-evaluated Flow record
>        values and passes only those Flow Records that match the criteria,
>        an Intermediate Flow Selection Process selects Flow Records using
>        selection criteria applicable to a larger set of Flow
>        characteristics and information.

For all the words, I only understood that IFSP is a superset of ISP - 
and I feel that I missed the point?


>
>
> 3.  Handling IPFIX Message Headers
>
>     The format of the IPFIX Message Header as exported by an IPFIX
>     Mediator is shown in Figure 1.  Note that the format is compatible
>     with the IPFIX Message Header defined in
>     [I-D.ietf-ipfix-protocol-rfc5101bis], with some field definitions
>     (for the example, the Export Time) updated in the context of the
>     IPFIX Mediator.
>
>
>
>
>
>
>
>
>
>
>
>
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>
>      0                   1                   2                   3
>      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>     |             Version           |            Length             |
>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>     |                           Export Time                         |
>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>     |                       Sequence Number                         |
>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>     |                    Observation Domain ID                      |
>     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
>                      Figure 1: IP Message Header format
>
>     The header fields as exported by an IPFIX Mediator are describe
>     below.
>
>     Version:   Version of IPFIX to which this Message conforms.  The
>        value of this field is 0x000a for the current version,
>        incrementing by one the version used in the NetFlow services
>        export version 9 [RFC3954].
>
>     Length:   Total length of the IPFIX Message, measured in octets,
>        including Message Header and Set(s).
>
>     Export Time:   Time at which the IPFIX Message Header leaves the
>        IPFIX Mediator, expressed in seconds since the UNIX epoch of 1
>        January 1970 at 00:00 UTC, encoded as an unsigned 32-bit integer.
>        However, in the specific case of an IPFIX Mediator containing an
>        Intermediate Conversion Process, the IPFIX Mediator MAYkeep  the
>        export time received from the incoming Transport Session.

I know exactly what you're saying here, but others might not. I suggest 
s/keep/use/.


>
>     Sequence Number:   Incremental sequence counter modulo 2^32 of all
>        IPFIX Data Records sent in a the current stream from the current
>        Observation Domain by the Exporting Process.  Each SCTP Stream
>        counts sequence numbers separately, while all messages in a TCP
>        connection or UDP transport session are considered to be part of
>        the same stream.  This value SHOULD be used by the Collecting
>        Process to identify whether any IPFIX Data Records have been
>        missed.  Template and Options Template Records do not increase the
>        Sequence Number.
>
>     Observation Domain ID:   A 32-bit identifier of the Observation
>        Domain that is locally unique to the Exporting Process.  The
>        Exporting Process uses the Observation Domain ID to uniquely
>        identify to the Collecting Process the Observation Domain that
>        metered the Flows.  It is RECOMMENDED that this identifier also be
>        unique per IPFIX Device.  Collecting Processes SHOULD use the
>
>
>
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>        Transport Session and the Observation Domain ID field to separate
>        different export streams originating from the same Exporter.  The
>        Observation Domain ID SHOULD be 0 when no specific Observation
>        Domain ID is relevant for the entire IPFIX Message, for example,
>        when exporting the Exporting Process Statistics, or in case of a
>        hierarchy of Collectors when aggregated Data Records are exported.
>        See Section 4.1 for special considerations for Observation Domain
>        management while passing unmodified templates through an IPFIX
>        Mediator, and Section 5 for guidelines for preservation of
>        original Observation Domain information at an IPFIX Mediator.
>
>     The following specifications, copied over from
>     [I-D.ietf-ipfix-protocol-rfc5101bis] have some implications in this
>     document: "Template Withdrawals MAY appear interleaved with Template
>     Sets, Options Template Sets, and Data Sets within an IPFIX Message.
>     In this case, the Templates and Template Withdrawals shall be taken
>     to take effect in the order in which they appear in the IPFIX
>     Message."
>
>     If an IPFIX Mediator receives an IPFIX Message composed of Template
>     Withdrawals and Template Sets, and if the IPFIX Mediator forwards
>     this IPFIX Message, it MUST not modify the Set order.  Note that the

TWM + Template definitions in separate messages must also not be re-ordered.


>     Template Mapping (see section 4.1) is theauthorative  source of

Typo, "authoritative".


>     information on the IPFIX Mediator to decide whether the entire IPFIX
>     Messages can be forwarded as such.
>
>
> 4.  Template Management
>
>     How an IPFIX Mediator handles the Templates it receives from the
>     Original Exporter depends entirely on the nature of the Intermediate
>     Process running on that IPFIX Mediator.
>
>     IPFIX Mediators that passsubstantially the same  Data Records from
>     the Original Exporter downstream, (e.g., an Intermediate Selection
>     Process), pass unmodified Template as described in Section 4.1; this

I can't parse this properly - partly because the comma section is 
completely parenthesised.

What does "substantially the same Data Records" mean? It could be:

     * the same data records, +/- a field or two.
     * the same fields, +/- some records.

Should "Template" be plural?


>     section describes a Template Mapping required to make this work in
>     the general case, and the correlation between thereceivd  and
>     generated IPFIX Message Withdrawals.

Typo, "received".


>
>     IPFIX Mediators that export Data Records which aresubstantially
>     changed  from the Data Records received from the Original Exporter

What does "substantially changed" mean?

     * fields reordered, added, or removed
     * fields unmodified, but records added / removed


>     follow the guidelines in Section 4.2 instead: in this case, the IPFIX
>     Mediator generates new (Options) Template Records as a result of the
>     Intermediate Process, and no Template Mapping is required.
>
>     Subsequent subsections deal with specific issues in Template
>     management that may occur at IPFIX Mediators.
>
>
>
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> 4.1.  Passing Unmodified Templates through an IPFIX Mediator
>
>     The first case  is a situation where the IPFIX Mediator doesn't modify

The "second case" is 5 pages away at the bottom of page 15. Perhaps just 
say, "In this case, the IPFIX Mediator...".


>     the (Options) Template Record(s) content.  A typical example is an

Hurrah, a definition of "substantially the same"!


>     Intermediate Flow Selection Process acting as distributor, which
>     collects Flow Records from one or more Exporters, and based on the
>     Information Elements content, redirects the Flow Records to the
>     appropriate Collector.  This example is a typical case of a single
>     network operation center managing multiple universities: an unique
>     IPFIX Collector collects all Flow Records for the common
>     infrastructure, but might be re-exporting specific university Flow
>     Records to the responsible system administrator.

Does this case include the situation where incoming templates contain 
the same fields, but in a different order? So the mediator could 
re-order the fields and export the contents with a single outgoing 
Template. [Later: subject to key fields, per below.]


>
>     As specified in [I-D.ietf-ipfix-protocol-rfc5101bis], the Template
>     IDs are unique per Exporter, per Transport Session, and per
>     Observation Domain.  As there is no guarantee that, for similar
>     Template Records, the Template IDs received on the incoming Transport
>     Session and exported to the outgoing Transport Session would be same,
>     the IPFIX Mediator MUST maintain a Template Mapping composed of
>     related received and exported (Options) Template Records:
>
>     o  for each received (Options) Template Record: Template Record
>        Information Elements, Template ID, Observation Domain Id, and
>        Transport Session Information,metada  scoped to the Template (*)

Typo, "metadata".


>
>     o  for each exported (Options) Template Record: Template Record
>        Information Elements, Template ID, Collector, Observation Domain
>        Id, and Transport Session Information metadata scoped to the
>        Template (*)
>
>     (*)The "metadata scoped to the Template" encompasses the metadata,
>     that are scoped to the Template,

I'm glad you explained; I'd never have guessed.


>     and that help to determine the
>     semantics of the Template Record.  Note that these metadata are
>     typically sent in Data Records described by an Options Template.  A
>     example is the flowKeyIndicator: An IPFIX Mediator could potentially
>     received two different Template IDs, from the same Exporter, with the
>     same Information Elements, but with a different set of Flow Keys
>     (indicated by the flowKeyIndicator in an Options Template Record).

This complicates my question about field-ordering above.


>     Another example is the combination of anonymizationFlags and
>     anonymizationTechnique [RFC6235]).  This metadata information must be
>     present in the Template Mapping, to stress that the two Template
>     Record semantics are different.

So templates can potentially be merged provided that the semantics are 
the same.


>
>     If an IPFIX Mediator receives an IPFIX Withdrawal Message for a
>     (Options) Template Record that is not used anymore in any other
>     Template Mappings, the IPFIX Mediator SHOULD export the appropriate
>     IPFIX Withdrawal Message(s) on the outgoing Transport Session, and
>     remove the corresponding entry in the Template Mapping.
>
>
>
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>
>
>     If a (Options) Template Record is not used anymore in an outgoing
>     Transport Session, it MUST be withdrawn with an IPFIX Template
>     Withdrawal Message on that specific outgoing Transport Session, and
>     its entry MUST be removed from the Template Mapping.
>
>     If an incoming or outgoing Transport Session is gracefully shutdown
>     or reset, the (Options) Template Records corresponding to that
>     Transport Session MUST be removed from the Template Mapping.
>
>     For example, Figure 2 displays an example of an Intermediate Flow
>     Selection Process, re-distributing Data Records to Collectors on the
>     basis of customer networks, i.e. the Route Distinguisher (RD).  In
>     this example, the Template Record received from the Exporter #1 is
>     reused towards Collector #1, Collector #2, and Collector #3.

If the incoming template is reused, then why does customer A receive 
Template 256, while customers B and C receive Template 257? What's the 
difference between Template 256 and Template 257?


>
>                                         Tmpl.  .---------.
>                                         ID 256 |         |
>                                          .---->|Collector|<==>Customer
>                                          |     |#1       |    A
>                                          |     |         |
>                                       RD=100:1 '---------'
>        .---------.Templ.  .---------.    |
>        |         |Id      |         |----'     .---------.
>        |         |258     |         | RD=100:2 |         |
>        |IPFIX    |------->|IPFIX    |--------->|Collector|<==>Customer
>        |Exporter |        |Mediator | Tmpl.    |#2       |    B
>        |#1       |        |         | ID 257   |         |
>        |         |        |         |----.     '---------'
>        '---------'        '---------'    |
>                                         RD=100:3
>                                    Tmpl. |     .---------.
>                                    ID    |     |         |
>                                    257   '---->|Collector|<==>Customer
>                                                |#3       |    C
>                                                |         |
>                                                '---------'
>
>             Figure 2: Intermediate Flow Selection Process example

The middle of the figure is hideously cramped, in the area under 
RD=100:2. Some vertical spacing would really help.

Also there's enough room to write "Customer A" without wrapping. 
Additionally 2 columns can be recovered by narrowing the Exporter and 
Mediator boxes. The figure can also be pulled up to 3 spaces leftwards 
if needs be.

"Templ. Id 258" is inconsistent with "Tmpl. ID nnn" everywhere else.

So, putting that all together, let me redraw the figure for you:

                                             .---------.
                                 Tmpl.       |         |
                                 ID    .---->|Collector|<==>Customer A
                                 256   |     |   #1    |
                                       |     |         |
                                    RD=100:1 '---------'
       .--------.        .--------.    |
       |        | Tmpl.  |        |----'
       |        | Id     |        |          .---------.
       |        | 258    |        | RD=100:2 |         |
       | IPFIX  |------->| IPFIX  |--------->|Collector|<==>Customer B
       |Exporter|        |Mediator| Tmpl.    |   #2    |
       |   #1   |        |        | ID 257   |         |
       |        |        |        |          '---------'
       |        |        |        |----.
       '--------'        '--------'    |
                                    RD=100:3
                                       |     .---------.
                                 Tmpl. |     |         |
                                 ID    '---->|Collector|<==>Customer C
                                 257         |   #3    |
                                             |         |
                                             '---------'


>
>     Figure 3 shows the Template Mapping for the system shown in Figure 2.
>
>
>
>
>
>
>
>
>
>
>
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>
>     Template Entry A:
>     Incoming Transport Session Information (from Exporter#1):
>       Source IP: <Exporter#1 export IP address>
>       Destination IP: <IPFIX Mediator IP address>
>       Protocol: SCTP
>       Source Port: <source port>
>       Destination Port: 4739 (IPFIX)
>     Observation Domain Id: <Observation Domain ID>
>     Template Id: 258
>     Metada  scoped to the Template : <not applicable in this case>

Typo.

>
>     Template Entry B:
>     Outgoing Transport Session Information (to Collector#1):
>       Source IP: <IPFIX Mediator IP address>
>       Destination IP: <IPFIX Collector#1 IP address>
>       Protocol: SCTP
>       Source Port: <source port>
>       Destination Port: 4739 (IPFIX)
>     Observation Domain Id: <Observation Domain ID>
>     Template Id: 256
>     Metada  scoped to the Template : <not applicable in this case>

Typo.


>
>     Template Entry C:
>     Outgoing Transport Session Information (to Collector#2):
>       Source IP: <IPFIX Mediator IP address>
>       Destination IP: <IPFIX Collector#2 IP address>
>       Protocol: SCTP
>       Source Port: <source port>
>       Destination Port: 4739 (IPFIX)
>     Observation Domain Id: <Observation Domain ID>
>     Template Id: 257
>     Metada  scoped to the Template : <not applicable in this case>

Typo.


>
>     Template Entry D:
>     Outgoing Transport Session Information (to Collector#3):
>       Source IP: <IPFIX Mediator IP address>
>       Destination IP: <IPFIX Collector#3 IP address>
>       Protocol: SCTP
>       Source Port: <source port>
>       Destination Port: 4739 (IPFIX)
>     Observation Domain Id: <Observation Domain ID>
>       Template Id: 257
>     Metada  scoped to the Template : <not applicable in this case>

Indentation of "Template ID: 257" is inconsistent with usage above.

Typo, "metadata".

BTW, note the potential for confusion where:
     Template Entry B corresponds to customer A
     Template Entry C corresponds to customer B
     Template Entry D corresponds to customer C


>
>                 Figure 3: Template Mapping example: templates
>
>     The Template Mapping corresponding tofigure B  can be displayed as:

Where is "figure B" ?


>
>
>
>
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>
>     Template Entry A   <----> Template Entry B
>     Template Entry A   <----> Template Entry C
>     Template Entry A   <----> Template Entry D
>
>                      Template Mapping example: mappings
>
>     Alternatively, the Template Mapping may be optimized as:
>
>                           +--> Template Entry B
>                           |
>     Template Entry A   <--+--> Template Entry C
>                           |
>                           +--> Template Entry D
>
>                      Template Mapping example: mappings

Please label this Figure in case someone wants to refer to it in future 
work. Also please add one line saying "Figure 3a shows stuff" so that 
the figure isn't orphaned.

The text immediately above Figure 2 says, "In this example, the Template 
Record received from the Exporter #1 is reused towards Collector #1, 
Collector #2, and Collector #3." So why is the template mapping not simply:

         Template Entry A <----> Template Entry A'


>
>     Note that all examples use Transport Sessions based on the SCTP
>     protocol, as simplified use cases.  However, theprotocol  would be
>     important in situations such as an Intermediate Conversion Process
>     doing transport protocol conversion.

Clarify "protocol" = transport protocol, rather than IPFIX protocol.


>
> 4.1.1.  Template Mapping and Information Element Ordering
>
>     In the situation where Original Exporters each export an (Options)
>     Template to a single IPFIX Mediator, and the (Options) Template
>     Record contains the same Information Elements but in different order,
>     should the IPFIX Mediator maintain a Template Mapping with a single
>     Export Template Record (see figure "Template Mapping and Ordering: a
>     single Export Template Record") or should the IPFIX Mediator maintain
>     multiple independent Template Records (see figure "Template Mapping
>     and Ordering: multiple Export Template Record") before re-exporting
>     to the Collector?

NO. Give them a simple name, eg "Figure 4" and "Figure 5".


>
>             Template Entry A   <--+
>                                   |
>             Template Entry B   <--+--> Template Entry D
>                                   |
>             Template Entry C   <--+
>
>        Template Mapping and Ordering: a single Export Template Record
>
>
>             Template Entry A   <--+--> Template Entry D
>
>             Template Entry B   <--+--> Template Entry E
>
>             Template Entry C   <--+--> Template Entry F
>
>
>
>
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>
>        Template Mapping and Ordering: multiple Export Template Records

Label these figures, because they're referenced within this document.


>
>     The answer depends whether the order of the Information Elements
>     implies some specific semantic.  One of the guiding principles in
>     IPFIX protocol specificationsis  that the semantic meaning of one
>     Information Element doesn't depend on the value ofthe different
>     Information Element.  However, there is one noticeable exception, as
>     mentioned in [I-D.ietf-ipfix-protocol-rfc5101bis]:

Missing word, "is". BTW, where is this (often cited) principle actually 
stated?

s/the different/another/, or /any other/


>
>     "Multiple Scope Fields MAY be present in the Options Template Record,
>     in which case, the composite scope is the combination of the scopes.
>     For example, if the two scopes are meteringProcessId and templateId,
>     the combined scope is this Template for this Metering Process.  If a
>     different order of Scope Fields would result in a Record having a
>     different semantic meaning, then the order of Scope Fields MUST be
>     preserved by the Exporting Process.  For example, in the context of
>     PSAMP [RFC5476], if the first scope defines the filtering function,
>     while the second scope defines the sampling function, the order of
>     the scope is important.  Applying the sampling function first,
>     followed by the filtering function, would lead to potentially
>     different Data Records than applying the filtering function first,
>     followed by the sampling function."
>
>     If an IPFIX Mediator receives, from multiple Exporters, Template
>     Records with identical Information Elements, but ordered differently,
>     it SHOULD consider those Template Records as identical.

Almost: subject to metadata in options, eg flowKeyIndicator.


>
>     If an IPFIX Mediator receives, from multiple Exporters, Options
>     Template Records with identical and ordered Information Elements in
>     the Scope fields, and with identical Information Elements, but
>     ordered differently, in the non Scope fields, it SHOULD consider
>     those Template Records as identical.
>
>     If an IPFIX Mediator receives, from multiple Exporters, Options
>     Template Records with identical Information Elements in the scope,
>     but ordered differently, it MUST consider those Template Records as
>     semantically different.

Basically scope == key fields, so this agrees with my assertion above.

(BTW, if we do IPFIX-2, then we should *only* have options templates, 
with zero or more scope fields. Think how much simpler that'd make all 
the drafts!)


>
> 4.2.  Creating New Templates at an IPFIX Mediator
>
>     The second case is a situation where the IPFIX Mediator generates new
>     (Options) Template Records as a result of the Intermediate Process.

As predicted, I already forgot that there was a first case.


>
>     In this situation, the IPFIX Mediator doesn't need to maintain a
>     Template Mapping, as it generates its own series of (Options)
>     Template Records.  However, the following special case might still
>     require a Template Mapping, i.e. a situation where the IPFIX
>     Mediator, typically containing an Intermediate Conversion Process,
>
>
>
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>
>     Intermediate Aggregation Process, or Intermediate Anonymization
>     Process in case of black-marker Anonymization [RFC6235], generates
>     new (Options) Template Records based on what it receives from the
>     Exporter(s), and based on the Intermediate Process function.  In such
>     a case,it's important to keep the correlation between the received
>     (Options) Template Records and exported Derived (Options) Template
>     Records in the Template Mapping.  These Template Mappings would be
>     kept as in Section 4.1, except that the exported Template would not
>     be identical to the received Template.

It took me a while to parse this correctly. s/exported/the/ would help 
considerably.

"Derived (Options) Template" isn't defined.


>
> 4.3.  Handling Unknown Information Elements
>
>     Depending on application requirements, Mediators which do not
>     generate new Records SHOULD re-export values for unknown Information
>     Elements, whether enterprise-specific Information Elements or
>     Information Elements in theIANA IPFIX Information Element registry
>     added since the Mediator was implemented or updated.  However, as
>     there may be presence or ordering dependencies among the unknown
>     Information Elements, the Mediator MUST NOT omit fields from such re-
>     exported Records, or re-order any fields within the Records.

Add a reference for IANA's registry. BTW, it'd be nice to use a 
consistent phrase for that throughout all the WG drafts.

May a Mediator append fields? That too could lead to ambiguity, eg if 
any of the unknown fields is a bitmap describing the other fields, it 
wouldn't correctly describe any appended fields.


>
>     Mediators which generate new Records, as in Section 4.2, SHOULD NOT
>     use values of Information Elements they do not understand.  If they
>     do pass such values, they MUST NOT pass values of unknownInformaiton
>     Elements unless all such values are passed on in the original order
>     in which they were received.

Typo.


>
>     In any case, Mediators handling unknown Information Elements SHOULD
>     log this fact, as it is likely that mediation of records containing
>     unknown values will have unintended consequences.
>
>
> 5.  Preserving Original Observation Point Information
>
>     Depending on the use case, the Collector in an Exporter - IPFIX
>     Mediator - Collector structure may need to receive information about
>     the Original Observation Point(s), otherwise it may wrongly conclude
>     that the IPFIX Device exporting the Flow Records, i.e. the IPFIX
>     Mediator, directly observed the packets that generated the Flow
>     Records.  Two new Information Elements are introducedin the
>     subsections belowto address this use case:

Remove "in the subsections below". In the IANA section, I'll argue that 
it'd be better for all the new IEs to be in the IANA section.


>     originalExporterIPv4Address and originalExporterIPv6Address.
>     Practically, the Original Exporterswill not exporting  these

"will not be exporting"

What about the case of tiered Mediators? Perhaps the 
originalExporter*Address should be passed-through.


>     Information Elements.  Therefore, the Intermediate Process SHOULD
>     report the Original Observation Point(s) to the best of its
>     knowledge.Note that the Configuration Data Model for IPFIX and
>     PSAMP [RFC6728] may help.

Help in what way?


>
>
>
>
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>
>     In the IPFIX Mediator, the Observation Point(s) may be represented
>     by:
>
>     o  A single Original Exporter (represented by the
>        originalExporterIPv4Address or originalExporterIPv6Address
>        Information Elements)
>
>     o  A list of Original Exporters (represented bythe
>        originalExporterIPv4Address or originalExporterIPv6Address
>        Information Elements).

s/the/a list of/


>
>     o  Any combination or list of Information Elements representing
>        Observation Points.  For example:
>
>        *  A list of Original Exporter interface(s) (represented by the
>           originalExporterIPv4Address or originalExporterIPv6Address, the
>           ingressInterface and/or egressInterface Information Elements,
>           respectively)
>
>        *  A list of Original Exporter line card (represented by the
>           originalExporterIPv4Address or originalExporterIPv6Address, the
>           lineCardId Information Elements, respectively)
>
>     Some Information Elements characterizing the Observation Point may be
>     added.  For example, the flowDirection Information Element specifies
>     the direction of the observation, and, as such, characterizes the
>     Observation Point.
>
>     Any combination of the above representations is possible.  For
>     example, in case of an Intermediate Aggregation Process, an Original
>     Observation Point could be composed of:
>
>     exporterIPv4Address 192.0.2.1
>     exporterIPv4Address 192.0.2.2,
>       interface ethernet 0, direction ingress
>       interface ethernet 1, direction ingress
>       interface serial 1, direction egress
>       interface serial 2, direction egress
>     exporterIPv4Address 192.0.2.3,
>       lineCardId 1, direction ingress
>
>            Figure 4: Complex Observation Point Definition Example

This figure is orphaned. Add a line saying "Figure 4 shows some 
interesting stuff".


>
>     If the Original Observation Point is composed of a list, thenthe
>     IPFIX Structured Data [RFC6313] MUST be used to export it from the
>     IPFIX Mediator.

Remove "the".


>
>     The most generic way to export the Original Observation Point is to
>
>
>
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>
>
>     use a subTemplateMultiList, with the semantic "exactlyOneOf".  Taking
>     the previous example, the following encoding can be used:
>
>     Template Record 257: exporterIPv4Address
>     Template Record 258: exporterIPv4Address,
>                          basicList of ingressInterface, flowDirection
>     Template Record 259: exporterIPv4Address, lineCardId, flowDirection
>
>       Figure 5: Complex Observation Point Definition Example: Templates

This figure is orphaned. Above say, "the encoding in Figure 5 can be used:".


>
>     The Original Observation Point is modeled with the Data Records
>     corresponding to either Template Record 1, Template Record 2, or
>     Template Record 3 but not more than one of these ("exactlyOneOf"
>     semantic).  This implies that the Flow was observed at exactly one of
>     the Observation Points reported.
>
>     When an IPFIX Mediator receives Flow Records containing the Original
>     Observation Point Information Element, i.e.
>     originalExporterIPv6Address or originalExporterIPv4Address, the IPFIX

Why put IPv6 first, before IPv4? This is inconsistent with earlier usage.


>     Mediator SHOULD NOT modify its value(s) when composing new Flow
>     Records in the general case.  Known exceptions include anonymization
>     per [RFC6235] section 7.2.4 and an Intermediate Correlation Process
>     rewriting addresses across NAT.  In other words, the Original
>     Observation Point should not be replaced with the IPFIX Mediator
>     Observation Point.  The daisy chain of (Exporter, Observation Point)
>     representing the path the Flow Records took from the Exporter to the
>     top Collector in the Exporter - IPFIX Mediator(s) - Collector
>     structure model is out of the scope of this specification.
>
> 5.1.  originalExporterIPv4Address Information Element
>
>     Description:   The IPv4 address used by the Exporting Process on an
>        Original Exporter, as seen by the Collecting Process on an IPFIX
>        Mediator.  Used to provide information about the Original
>        Observation Points to a downstream Collector.
>
>     Data Type:   ipv4Address
>
>     ElementId:   TBD1
>
> 5.2.  originalExporterIPv6Address Information Element
>
>     Description:   The IPv6 address used by the Exporting Process on an
>        Original Exporter, as seen by the Collecting Process on an IPFIX
>        Mediator.  Used to provide information about the Original
>        Observation Points to a downstream Collector.
>
>
>
>
>
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>
>     Data Type:   ipv6Address
>
>     ElementId:   TBD2

In the IANA section, I'll argue that it'd be better for all the new IEs 
to be in the IANA section.


>
>
> 6.  Managing Observation Domain IDs
>
>     In any case,  the Observation Domain ID of any IPFIX Message

"In any case" probably worked when this text followed directly from some 
previous argument. However, it seems out of place here. It could be 
dropped with no loss of meaning.


>     containing Flow Records relevant to no particular Observation Domain,
>     or to multiple Observation Domains, MUST have an Observation Domain
>     ID of 0, as in Section 3 above, and section 3.1 of
>     [I-D.ietf-ipfix-protocol-rfc5101bis].

So are we saying that OD zero has a special meaning? Should existing 
exporters avoid using OD zero in order to avoid confusing Collectors?


>
>     IPFIX Mediators that do not change (Options) Template Records MUST
>     maintain a Template Mapping, as detailed in Section 4.1, to ensure
>     that the combination of Observation Domain IDs and Template IDs do
>     not collide on export.
>
>     For IPFIX Mediators that export New (Options) Template Records, as in
>     Section 4.2, there are two options for Observation Domain ID
>     management.  The first and simplest of these is to completely
>     decouple exported Observation Domain IDs from received Observation
>     Domain IDs; the IPFIX Mediator, in this case, comprises its own set
>     of Observation Domain(s) independent of the Observation Domain(s) of
>     the Original Exporters.
>
>     The second option is to provide or maintain a Template Mapping for
>     received (Options) Template Records and exported inferred (Options)
>     Template Records, along with the appropriate Observation Domain IDs
>     per Transport Session, which ensures that the combination of
>     Observation Domain IDs and Template IDs do not collide on export.
>
>     In some cases where the IPFIX Message Header can't contain a
>     consistent Observation Domain for the entire IPFIX Message, but the
>     Flow Records exported from the IPFIX Mediator should anyway contain
>     the Observation Domain of the Original Exporter, the (Options)
>     Template Record must contain theoriginalObservationDomainId

Specified in s6.1 below.


>     Information Element.  When an IPFIX Mediator receives Flow Records
>     containing the originalObservationDomainId Information Element, the
>     IPFIX Mediator MUST NOT modify its value(s) when composing new Flow
>     Records with the originalObservationDomainId Information Element.
>
> 6.1.  originalObservationDomainId Information Element
>
>
>
>
>
>
>
>
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>
>
>     Description:   The Observation Domain ID reported by the Exporting
>        Process on an Original Exporter, as seen by the Collecting Process
>        on an IPFIX Mediator.  Used to provide information about the
>        Original Observation Domain to a downstream Collector.
>
>     Data Type:   unsigned32
>
>     Data Type Semantics:   identifier
>
>     ElementId:   TBD3

Is this definition sufficient for the revised IANA registry format?


>
>
> 7.  Timing Considerations
>
>     The IPFIX Message Header "Export Time" field is the time in seconds
>     since 0000 UTC Jan 1, 1970, at which the IPFIX Message leaves the
>     IPFIX Mediator.  However, in the specific case of an IPFIX Mediator
>     containing an Intermediate Conversion Process, the IPFIX Mediator MAY
>     keep the export time received from the incoming Transport Session.

Again, although I know exactly what you're saying here, others might 
not. I suggest s/keep/use/.


>
>     It is RECOMMENDED that IPFIX Mediators handle time using absolute
>     timestamps (e.g. flowStartSeconds, flowStartMilliseconds,
>     flowStartNanoseconds), which are specified relative to the UNIX epoch
>     (00:00 UTC 1 Jan 1970), where possible, rather than relative
>     timestamps (e.g. flowStartSysUpTime, flowStartDeltaMicroseconds),
>     which are specified relative to protocol structures such as system
>     initialization or message export time.
>
>     The latter are difficult to manage for two reasons.  First, they
>     require constant translation, as the system initialization time of an
>     intermediate system and the export time of an intermediate message
>     will change across mediation operations.  Further, relative
>     timestamps introduce range problems.  For example, when using the
>     flowStartDeltaMicroseconds and flowEndDeltaMicroseconds Information
>     Elements [iana-ipfix-assignments], the Data Record must be exported
>     within a maximum of 71 minutes after its creation.  Otherwise, the
>     32-bit counter would not be sufficient to contain the flow start time
>     offset.  Those time constraints might be incompatible with some of
>     the application requirements of some Intermediate Processes.
>
>     Intermediate Processes MUST NOT assume that received records appear
>     in flowStartTime, flowEndTime, or observationTime order.  An
>     Intermediate Process processing timing information (e.g., an
>     Intermediate Aggregation Process) MAY ignore records that are
>     significantly out of order, in order to meet application-specific
>     state and latency requirements, but SHOULD report that records were
>     dropped.
>
>
>
>
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>
>
>     When an Intermediate Process aggregates information from different
>     Flow Records, the timestamps on exported records SHOULD be the
>     minimum of the start times and the maximum of the end times in the
>     general case.  However, if the Flow Records do not overlap, i.e. if
>     there is a time gap between the times in the Flow Records, then the
>     report may be inaccurate.  The IPFIX Mediator is only reporting what
>     it knows, on the basis of the information made available to it - and
>     there may not have been any data to observe during the gap.  Then
>     again, if there is an overlap in timestamps, there's the potential of
>     double-accounting: different Observation Points may have observed the
>     same traffic simultaneously.Therefore, as there is not a single
>     rule that fits all different situations, a complete specification of
>     the precise rules of applying Flow Record timestamps at IPFIX
>     Mediators is out of the scope of this document.

Too hard and can't be bothered? :-(


>
>     Note that [I-D.ietf-ipfix-a9n] provides additional specifications for
>     handling of timestamps at an Intermediate Aggregation Process.
>
>
> 8.  Transport Considerations
>
>     SCTP [RFC4960] using the PR-SCTP extension specified in [RFC3758]
>     MUST be implemented by all compliant IPFIX Mediator implementations.
>     TCP [RFC0793] MAY also be implemented by IPFIX Mediator compliant
>     implementations.  UDP [RFC0768] MAY also be implemented by compliant
>     IPFIX Mediator implementations.  Transport-specific considerations
>     for IPFIX Exporters as specified in sections 8.3, 8.4, 9.1, 9.2, and
>     10 of [I-D.ietf-ipfix-protocol-rfc5101bis] apply to IPFIX Mediators
>     as well.
>
>     SCTP SHOULD be used in deployments where IPFIX Mediators and
>     Collectors are communicating over links that are susceptible to
>     congestion.  SCTP is capable of providing any required degree of
>     reliability.  TCP MAY be used in deployments where IPFIX Mediators
>     and Collectors communicate over links that are susceptible to
>     congestion, but SCTP is preferred due to its ability to limit back
>     pressure on Exporters and its message versus stream orientation.  UDP
>     MAY be used, although it is not a congestion-aware protocol.
>     However, in this case, the IPFIX traffic between IPFIX Mediator and
>     Collector MUST run in an environment where IPFIX traffic has been
>     provisioned for, or iscontained  through some other means.

Explain "contained"?


>
>
> 9.  Collecting Process Considerations
>
>     Any Collecting Process compliant with
>     [I-D.ietf-ipfix-protocol-rfc5101bis] can receive IPFIX Messages from
>     an IPFIX Mediator.  If the IPFIX Mediator uses IPFIX Structured Data
>
>
>
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>
>     [RFC6313] to export Original Exporter Information as in Section 5,
>     the Collecting Process MUST support [RFC6313].
>
>
> 10.  Specific Reporting Requirements
>
>     IPFIX provides Options Templates forthe reporting on  the reliability

"for reporting the reliability"


>     of processes within the IPFIX Architecture.  As each Mediator
>     includes at least one IPFIX Exporting Process, they SHOULD use the
>     Exporting Process Reliability Statistics Options Template, as
>     specified in [I-D.ietf-ipfix-protocol-rfc5101bis].
>
>     Analogous to the Metering Process Reliability Statistics Options
>     Template, also specified in [I-D.ietf-ipfix-protocol-rfc5101bis],
>     Mediators SHOULD implement the Intermediate Process Reliability
>     Statistics Options Template, specified in the subsection below.

Which subsection? Add an xref.


>
>     The Flow Keys Options Template, as specified in
>     [I-D.ietf-ipfix-protocol-rfc5101bis], may require special handling at
>     an IPFIX Mediator as described below.

Described where? Add an xref.


>
>     In addition, each Intermediate Process may have its own specific
>     reporting requirements (e.g.  Anonymization Records as in [RFC6235],
>     or the Aggregation Counter Distribution Options Template as in
>     [I-D.ietf-ipfix-a9n]); these SHOULD be implemented as necessary as
>     described in the specification for each Intermediate Process.
>
> 10.1.  Intermediate Process Reliability Statistics Template
>
>     The Intermediate Process Statistics Options Template specifies the
>     structure of a Data Record for reporting Intermediate Process
>     statistics.  It SHOULD contain the following Information Elements;
>     the intermediateProcessId Information Element is defined in
>     Section 10.3, and the ignoredRecordTotalCount Information Element is
>     defined in Section 10.4:
>
>     +-------------------------+-----------------------------------------+
>     | IE                      | Description                             |
>     +-------------------------+-----------------------------------------+
>     | observationDomainId     | An identifier of the Observation Domain |
>     | [scope]                 | (of messages exported by this           |
>     |                         | Mediator), locally unique to the        |
>     |                         | Intermediate Process, to which this     |
>     |                         | statistics record applies.              |
>     | intermediateProcessId   | An identifier for the Intermediate      |
>     | [scope]                 | Process to which this statistics record |
>     |                         | applies.                                |

The intermediateProcessId is essentially meaningless outside the 
Mediator, so what is the value in exporting it? ie, what exactly is its 
purpose at the collector?


>
>
>
>
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>
>     | ignoredRecordTotalCount | The total number of Data Records        |
>     |                         | received but not processed by the       |
>     |                         | Intermediate Process.                   |
>     | time first record       | The timestamp of the first record that  |
>     | ignored                 | was ignored by the Intermediate         |
>     |                         | Process.  For Data Records containing   |
>     |                         | timestamp ranges, this SHOULD be taken  |
>     |                         | from the start timestamp of the range;  |
>     |                         | for data records containing no timing   |
>     |                         | information, this SHOULD be taken from  |
>     |                         | the Export Time in the message header   |
>     |                         | ofthe containing IPFIX Message.  For   |

Is this the incoming IPFIX Message? So the Intermediate Process has to 
examine each incoming Message in some detail, even though it's ignoring 
them? How do you expect that to work?
Also, this supposes clock synchronisation.


>     |                         | this timestamp, any of the following    |
>     |                         | timestamp can be used:                  |
>     |                         | observationTimeSeconds,                 |
>     |                         | observationTimeMilliseconds,            |
>     |                         | observationTimeMicroseconds, or         |
>     |                         | observationTimeNanoseconds.             |
>     | time last record        | The timestamp of the last record that   |
>     | ignored                 | was ignored by the Intermediate         |
>     |                         | Process.  For Data Records containing   |
>     |                         | timestamp ranges, this SHOULD be taken  |
>     |                         | from the end timestamp of the range;    |
>     |                         | for data records containing no timing   |
>     |                         | information, this SHOULD be taken from  |
>     |                         | the Export Time in the message header   |
>     |                         | of the containing IPFIX Message.  For   |
>     |                         | this timestamp, any of the following    |
>     |                         | timestamp can be used:                  |
>     |                         | observationTimeSeconds,                 |
>     |                         | observationTimeMilliseconds,            |
>     |                         | observationTimeMicroseconds, or         |
>     |                         | observationTimeNanoseconds.             |
>     +-------------------------+-----------------------------------------+

Pleaseaddsomewhitespacetomakethetablereadable.


>
> 10.2.  Flow Key Options Template
>
>     The Flow Keys Option Template specifies the structure of a Data
>     Record for reporting the Flow Keys of reported Flows.  A Flow Keys
>     Data Record extends a particular Template Record that is referenced
>     by its templateId identifier.  The Template Record is extended by
>     specifying which of the Information Elements contained in the
>     corresponding Data Records describe Flow properties that serve as
>     Flow Keys of the reported Flow.  This Options Template is defined in
>     section 4.4 of [I-D.ietf-ipfix-protocol-rfc5101bis], and SHOULD be
>     used by Mediators for export as defined there.
>
>     When an Intermediate Process exports Data Records containing
>
>
>
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>
>     different Flow Keys from those received from the Original Exporter,
>     and the Original Exporter sent a Flow Keys Options record to the
>     IPFIX Mediator, the IPFIX Mediator MUST export a Flow Keys Options
>     record defining the the new set of Flow Keys.
>
> 10.3.  intermediateProcessId Information Element
>
>     Description:   An identifier of an Intermediate Process that is
>        unique per IPFIX Device.  Typically, this Information Element is
>        used for limiting the scope of other Information Elements.  Note
>        that process identifiers may be assigned dynamically; ie.,and
>        Intermediate Process may be re-started with a different ID.

s/and/an/


>
>     Data Type:   unsigned32
>
>     Data Type Semantics:   identifier
>
>     ElementId:   TBD4
>
> 10.4.  ignoredRecordTotalCount Information Element
>
>     Description:   The total number of received Data Records that the
>        Intermediate Process did not process since the (re-)initialization
>        of the Intermediate Process; includes only Data Records not
>        examined or otherwise handled by the Intermediate Process due to
>        resource constraints, not Data Records which were examined or
>        otherwise handled by the Intermediate Process but which merely do
>        not contribute to any exported Data Record due to the operations
>        performed by the Intermediate Process.

If a mediator is resource constrained, how can it accurately report this 
figure?


>
>     Data Type:   unsigned64
>
>     Data Type Semantics:   totalCounter
>
>     ElementId:   TBD5

Are the definitions in 10.3 and 10.4 sufficient for the revised IANA 
registry format?


>
>
> 11.  Configuration Management
>
>     In general, using IPFIX Mediators to combine information from
>     multiple Original Exporters requires a consistent configuration of
>     the Metering Processes behind these Original Exporters.  The details
>     of this consistency are specific to each Intermediate Process.
>     Consistency of configuration should be verified out of band, with the
>     MIB modules ([RFC6615] and [RFC6727]) or with the Configuration Data
>     Model for IPFIX and PSAMP [RFC6728]

Missing final period.


>
>
>
>
>
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>
> 12.  Security Considerations
>
>     As they act as both IPFIX Collecting Processes and Exporting
>     Processes, the Security Considerations for IPFIX Protocol

"for the IPFIX Protocol"


>     [I-D.ietf-ipfix-protocol-rfc5101bis] also apply to IPFIX Mediators.
>     The Security Considerations for IPFIX Files [RFC5655] also apply to
>     IPFIX Mediators that write IPFIX Files or use them for internal
>     storage.  However, there are a few specific considerations that IPFIX
>     Mediator implementations must also take into account.
>
>     By design, IPFIX Mediators are "men-in-the-middle": they intercede in
>     the communication between an Original Exporter (or another upstream
>     IPFIX Mediator) and a downstream Collecting Process.  This has two
>     important implications for the level of confidentiality provided
>     across an IPFIX Mediator, and the ability to protect data integrity
>     and Original Exporter authenticity across anIPIIX  Mediator.  These
>     are addressed in more detail in the Security Considerations for IPFIX
>     Mediators in [RFC6183].

Typo.


>
>     Note that, while IPFIX Mediators can use the exporterCertificate and
>     collectorCertificate Information Elements defined in [RFC5655] as
>     described in section 9.3 of [RFC6183] to export information about
>     X.509 identities in upstream TLS-protected Transport Sessions, this
>     mechanism cannot be used to provide true end-to-end assertions about
>     a chain of IPFIX Mediators: any IPFIX Mediator in the chain can
>     simply falsify the information about upstreamTransport Sessions In
>     situations where information about the chain of mediation is
>     important, it must be determined out of band.

Missing period: s/Transport Sessions In/Transport Sessions. In/


>
>
> 13.  IANA Considerations
>
>     This document specifiesn  new IPFIX Information Elements,

s/n/some/, or delete it.


>     originalExporterIPv4Address in Section 5.1,
>     originalExporterIPv6Address in Section 5.2, and
>     originalObservationDomainId in Section 6.1, to be added to the IPFIX
>     Information Element registry [iana-ipfix-assignments].  [IANA NOTE:
>     please add the three Information Elements as specified in the
>     references subsections, and change TBD1, TBD2, and TBD3 in this
>     document to reflect the assigned identifiers.]

Also intermediateProcessId(TBD4) in 10.4 and 
ignoredRecordTotalCount(TBD5) in 10.5.

Rather than having the new IEs sprinkled througout the document, I'd 
prefer to have all the definitions consolidated here in the IANA 
section, with xrefs from the text.
There's no advantage to defining them inline. As you see, the 
definitions are easily overlooked.


>
>
> 14.  Acknowledgments
>
>     We would like to thank the IPFIX contributors, specifically Paul
>     Aitken for his thorough review and Rahul Patel for his feedback and

s/review/reviews/

P.


>     comments.  This work is materially supported by the European Union
>     Seventh Framework Programme under grant agreement 257315 (DEMONS).
>
>
>
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>
> 15.  References
>
> 15.1.  Normative References
>
>     [RFC0768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768,
>                August 1980.
>
>     [RFC0793]  Postel, J., "Transmission Control Protocol", STD 7,
>                RFC 793, September 1981.
>
>     [RFC2119]  Bradner, S., "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., and P.
>                Conrad, "Stream Control Transmission Protocol (SCTP)
>                Partial Reliability Extension", RFC 3758, May 2004.
>
>     [RFC4960]  Stewart, R., "Stream Control Transmission Protocol",
>                RFC 4960, September 2007.
>
>     [RFC5655]  Trammell, B., Boschi, E., Mark, L., Zseby, T., and A.
>                Wagner, "Specification of the IP Flow Information Export
>                (IPFIX) File Format", RFC 5655, October 2009.
>
>     [RFC6313]  Claise, B., Dhandapani, G., Aitken, P., and S. Yates,
>                "Export of Structured Data in IP Flow Information Export
>                (IPFIX)", RFC 6313, July 2011.
>
>     [RFC6615]  Dietz, T., Kobayashi, A., Claise, B., and G. Muenz,
>                "Definitions of Managed Objects for IP Flow Information
>                Export", RFC 6615, June 2012.
>
>     [RFC6727]  Dietz, T., Claise, B., and J. Quittek, "Definitions of
>                Managed Objects for Packet Sampling", RFC 6727,
>                October 2012.
>
>     [RFC6728]  Muenz, G., Claise, B., and P. Aitken, "Configuration Data
>                Model for the IP Flow Information Export (IPFIX) and
>                Packet Sampling (PSAMP) Protocols", RFC 6728,
>                October 2012.
>
>     [I-D.ietf-ipfix-protocol-rfc5101bis]
>                Claise, B. and B. Trammell, "Specification of the IP Flow
>                Information eXport (IPFIX) Protocol for the Exchange of
>                Flow Information", draft-ietf-ipfix-protocol-rfc5101bis-06
>                (work in progress), February 2013.
>
>     [I-D.ietf-ipfix-information-model-rfc5102bis]
>
>
>
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>
>
>                Claise, B. and B. Trammell, "Information Model for IP Flow
>                Information eXport (IPFIX)",
>                draft-ietf-ipfix-information-model-rfc5102bis-10 (work in
>                progress), February 2013.
>
>     [I-D.ietf-ipfix-flow-selection-tech]
>                D'Antonio, S., Zseby, T., Henke, C., and L. Peluso, "Flow
>                Selection Techniques",
>                draft-ietf-ipfix-flow-selection-tech-13 (work in
>                progress), February 2013.
>
>     [I-D.ietf-ipfix-a9n]
>                Trammell, B., Wagner, A., and B. Claise, "Flow Aggregation
>                for the IP Flow Information Export (IPFIX) Protocol",
>                draft-ietf-ipfix-a9n-08 (work in progress), November 2012.
>
> 15.2.  Informative References
>
>     [RFC3917]  Quittek, J., Zseby, T., Claise, B., and S. Zander,
>                "Requirements for IP Flow Information Export (IPFIX)",
>                RFC 3917, October 2004.
>
>     [RFC3954]  Claise, B., "Cisco Systems NetFlow Services Export Version
>                9", RFC 3954, October 2004.
>
>     [RFC5470]  Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
>                "Architecture for IP Flow Information Export", RFC 5470,
>                March 2009.
>
>     [RFC5472]  Zseby, T., Boschi, E., Brownlee, N., and B. Claise, "IP
>                Flow Information Export (IPFIX) Applicability", RFC 5472,
>                March 2009.
>
>     [RFC5476]  Claise, B., Johnson, A., and J. Quittek, "Packet Sampling
>                (PSAMP) Protocol Specifications", RFC 5476, March 2009.
>
>     [RFC5610]  Boschi, E., Trammell, B., Mark, L., and T. Zseby,
>                "Exporting Type Information for IP Flow Information Export
>                (IPFIX) Information Elements", RFC 5610, July 2009.
>
>     [RFC5982]  Kobayashi, A. and B. Claise, "IP Flow Information Export
>                (IPFIX) Mediation: Problem Statement", RFC 5982,
>                August 2010.
>
>     [RFC6183]  Kobayashi, A., Claise, B., Muenz, G., and K. Ishibashi,
>                "IP Flow Information Export (IPFIX) Mediation: Framework",
>                RFC 6183, April 2011.
>
>
>
>
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>
>
>     [RFC6235]  Boschi, E. and B. Trammell, "IP Flow Anonymization
>                Support", RFC 6235, May 2011.
>
>     [iana-ipfix-assignments]
>                Internet Assigned Numbers Authority, "IP Flow Information
>                Export Information Elements
>                (http://www.iana.org/assignments/ipfix/ipfix.xml)".
>
>     [POSIX.1]  IEEE, "IEEE 1003.1-2008 - IEEE Standard for Information
>                Technology - Portable Operating System Interface".
>
>
> Authors' Addresses
>
>     Benoit Claise
>     Cisco Systems, Inc.
>     De Kleetlaan 6a b1
>     1831 Diegem
>     Belgium
>
>     Phone: [phone]
>     Email: [e-mail]
>
>
>     Atsushi Kobayashi
>     NTT Information Sharing Platform Laboratories
>     3-9-11 Midori-cho
>     Musashino-shi, Tokyo 180-8585
>     Japan
>
>     Phone: [phone]
>     Email: [e-mail]
>
>
>     Brian Trammell
>     Swiss Federal Institute of Technology Zurich
>     Gloriastrasse 35
>     8092 Zurich
>     Switzerland
>
>     Phone: [phone]
>     Email: [e-mail]
>
>
>
>
>
>
>
>
>
> Claise, et al.           Expires August 29, 2013               [Page 28]
>