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Internet Draft                                                J. Quittek
<draft-ietf-ipfix-reqs-02.txt>
Document: draft-ietf-ipfix-reqs-03.txt                   NEC Europe Ltd.
Expires: August December 2002                                          T. Zseby
                                                               FhI FOKUS
                                                               B. Claise
                                                           Cisco Systems
                                                               (Editors)

                                                           March
                                                               S. Zander
                                                                G. Carle
                                                               FhI FOKUS
                                                            K.C. Norseth
                                                              Consultant

                                                               June 2002

              Requirements for IP Flow Information Export
                     <draft-ietf-ipfix-reqs-02.txt>

                     <draft-ietf-ipfix-reqs-03.txt>

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026. [RFC 2026]. Internet-Drafts are
   working documents of the Internet Engineering Task Force (IETF), its
   areas, and its working groups. Note that other groups may also
   distribute working documents as Internet-Drafts.

   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
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   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.
   http://www.ietf.org/shadow.html

   Distribution of this document is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001). All Rights Reserved.


Abstract

   This memo defines requirements for the export of measured IP flow
   information out of routers, traffic measurement probes and
   middleboxes.

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.



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Table of Content

   1. Contents

   1 Introduction
   2. .................................................    2
   2 Terminology
   2.1. ..................................................    2
   2.1 IP Traffic Flows
   2.2. Flow ............................................    2
   2.2 Observation Point
   2.3. ..........................................    3
   2.3 Metering Process
   2.4. ...........................................    3
   2.4 Flow Record
   2.5. ................................................    4
   2.5 Export Process
   2.6. Flow Information Collector or Collector
   2.7. IPFIX device
   3. .............................................    4
   2.6 Collecting Process .........................................    4
   3 Applications Requiring IP Flow Information Export ............    4
   3.1 Usage-based Accounting .....................................    5
   3.2 Traffic Profiling ..........................................    5
   3.3 Traffic Engineering
   3.4 Attack/Intrusion Detection
   3.5 .................................    6
   3.4 QoS Monitoring
   4. .............................................    6
   4 Distinguishing Flows
   4.1. .........................................    7
   4.1 Interfaces
   4.2. .................................................    7
   4.2 IP Header Fields
   4.3. ...........................................    8
   4.3 Transport Header Fields
   4.4. ....................................    8
   4.4 MPLS Label
   4.5. .................................................    8
   4.5 DiffServ Code Point
   4.6. ........................................    8
   4.6 Header Compression and Encryption
   5. ..........................    8
   5 Metering Process
   5.1. .............................................    9
   5.1 Reliability
   5.2. ................................................    9
   5.2 Sampling
   5.3. ...................................................    9
   5.3 Overload Behavior
   5.4. ..........................................   10
   5.4 Timestamps
   5.5. .................................................   10
   5.5 Time Synchronization
   5.6. .......................................   10
   5.6 Timeout
   5.7. ....................................................   10
   5.7 Ignore Port Copy
   6. ...........................................   11
   6 Data Export
   6.1. ..................................................   11
   6.1 Information Model
   6.2. ..........................................   11
   6.2 Data Model
   6.3. .................................................   13
   6.3 Data Transfer
   6.3.1. ..............................................   13
   6.3.1 Congestion Awareness
   6.3.2. .....................................   13
   6.3.2 Reliability
   6.3.3. ..............................................   13
   6.3.3 Security
   6.4. .................................................   14
   6.4 Push and Pull Mode Reporting
   6.5. ...............................   14
   6.5 Regular Reporting Interval
   6.6. .................................   14
   6.6 Notification on Specific Events
   6.7. ............................   14
   6.7 Anonymization
   7. ..............................................   14
   7 Configuration
   8. ................................................   14
   8 General Requirements
   8.1. .........................................   15
   8.1 Openness
   8.2. ...................................................   15
   8.2 Scalability concerning measuring devices
   8.3. Concerning the Number of Export Processes ......   15
   8.3 Several Data Collectors .........................................   15
   9 Special Device Considerations ................................   16
   10 Security Considerations .....................................   17
   10.1 Disclosure of Flow Information Data .......................   18
   10.2 Forgery of Flow Records ...................................   18


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   9. Security Considerations
   10.


   10.3 Denial of Service (DoS) Attacks ...........................   19
   11 Acknowledgments
   11. .............................................   19
   12 References
   12. ..................................................   19
   13 Authors' Addresses ..........................................   20
   14 Full Copyright Statement ....................................   21
   Appendix: Derivation of Requirements form Target from Applications .........   22


1.  Introduction

   There are several applications that require flow-based IP traffic
   measurements. Such measurements could be performed by a router while
   forwarding the traffic, by a middlebox [MIDBOXTAX], [RFC3234], or by a traffic
   measurement probe attached to a line or a monitored port. This memo
   defines requirements for exporting traffic flow information out of
   these boxes for further processing by applications located on other
   devices. In section 2 3, a selection of such applications is presented.
   The following sections list requirements derived from these
   applications.

   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 [RFC2119].


2.  Terminology

   The following terminology is used within this document:

2.1.  IP Traffic Flows Flow

   There are several definitions of the term 'flow' being used by the
   Internet community. Within this document we use the following one:

   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 of packet header fields (eg. (e.g. destination IP
         address)

      2. one or more properties of the packet itself (eg. (e.g. packet
         length)

      3. one or more of fields derived from packet treatment (eg. (e.g. AS
         number)

   A packet is defined to belong to a flow if it completely satisfies
   all the defined properties of the flow.


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   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 with a specific sequence number.
   Please note that the flow definition does not necessarily match a
   general application-level end-to-end stream. However, an application
   may derive properties of application-level streams by processing
   measured flow data.



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2.2.  Observation Point

   The observation point is a location in the network where IP packets
   can be observed. Examples are 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.

   Please note that a coarse-grained observation point of one flow, for
   example a line card with several ports, may be the superset of
   several more fine-grained observation points of some other flows, for
   example the individual ports of the line card.

2.3.  Metering Process

   A

   The metering process is a set of actions performed on packets generates flow records. Input to the process are
   IP packet headers observed at an observation point in order to map them to a flow. A point. The metering
   process can include consists of a set of functions for that includes packet header
   capturing, timestamping, classification sampling, classifying, and
   sampling of packets. Typically, the metering process also includes
   maintainance maintaining flow
   records.

   The maintenance of flow records may include creating new records, computation of
   updating existing ones, computing flow statistics, deriving further
   flow properties, detecting flow expiration, passing flows record to
   the export process, and
   detection of deleting flow records.

   The sampling function and the classifying function may be applied
   more than once with different parameters. Figure 1 shows the sequence
   in which the functions are applied. Sampling is not illustrated in
   the figure, it may be applied before any other function.















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                           packet header capturing
                                     |
                                timestamping
                                     |
                                     v
                              +----->+
                              |      |
                              | classifying
                              |      |
                              +------+
                                     |
                          maintaining flow expiration. records
                                     |
                                     v


                 Figure 1: Functions of the metering process


2.4.  Flow Record

   A flow record contains information about a specific flow that was
   metered at an observation point. A flow record contains measured
   properties of the flow (e.g. the total number of bytes of all packets
   of the flow) and usually also characteristic properties of the flow
   (e.g. source IP address).

2.5.  Export Process

   The export process sends flow records to one or more collectors.  The
   flow records are generated by one or more metering processes.

2.6. Collector  Collecting Process

   The collector collecting process receives flow records from one or more export
   processes. The collector might collecting process or might store received flow
   record, records
   or further process them, but these actions are out of the scope of
   this document.

2.7. IPFIX device

   A device hosting at least a flow information export process.
   Typically, corresponding Observation points, metering processes, and
   export processes are co-located at this device, for example at a
   router.











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3.  Applications Requiring IP Flow Information Export

   The following list contains

   This section describes a selection of applications requiring IP flow
   information export. Because requirements for flow export listed in
   further sections below are derived from these applications, their
   selection is crucial. The goal of this requirements document is not
   to cover all possible applications with all their flow export
   requirements, but to cover applications which are considered to be of
   significant importance in today's or future IP networks, and for
   which requirements can be met with reasonable technical effort.


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   Please note, that the described applications can have a large number
   of differing implementations. Requirement details or the weighting of
   requirements could differ for specific implementations. Therefore we
   derive the requirements from the general functionality of the
   selected applications. Furthermore, the

   The list of applications should lead to a better understanding of the
   requirements which is particularly important when designing or
   implementing a traffic flow measuring device.

3.1 functions. A detailed overview of
   which requirement was derived from which application(s) is given in
   the appendix.

3.1.  Usage-based Accounting

   Several new business models for selling IP service and IP-based
   services are currently under investigation. Beyond flat rate services
   which do not need accounting, accounting for these models can be
   based on time or volume. Accounting data can serve as input for
   billing systems. Accounting can be performed per user or per user
   group, it can be performed just for basic IP service or individually
   per high-level service and/or per content type delivered. For
   advanced/future services, accounting may also be performed per class
   of service, per application, per time of day, per used (label
   switched) path, etc.

3.2

3.2.  Traffic Profiling

   Traffic profiling is a process of characterizing IP flows and flow
   aggregates by using a model that represents key parameters of the
   flow
   flows such as flow duration, volume, time and burstiness. It is a
   prerequisite for network planning, network dimensioning, trend
   analysis, developing business models, and other activities. It
   heavily depends on the particular traffic profiling objective(s) what
   statistics and accuracy are required from the measurements. Typical
   information needed for traffic profiling are is the distribution of used
   services and protocols in the network, the amount of packets of a
   specific type (e.g. percentage of IPv6 packets) and specific flow
   profiles.

   Since objectives for traffic profiling can vary, this application



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   requires a high flexibility of the measurement infrastructure,
   especially regarding the options for measurement configuration and
   packet classification.

3.3 Traffic Engineering

   Traffic Engineering (TE) comprises methods for measurement, modeling,
   characterization and control of a network. The goal of TE is the
   optimization of network resource utilization and traffic performance
   [RFC2702]. Since control and administrative reaction to measurement
   results requires access to the involved network nodes, TE mechanisms
   and the required measurement function usually are performed within


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   one administrative domain. Typical parameters required for TE are
   link utilization, load between specific network nodes, number, size
   and entry/exit points of the active flows and routing information.

3.4

3.3.  Attack/Intrusion Detection

   Capturing of flow information plays an important role for network
   security, both for detection of security violation, and for
   subsequent defense. In case of a Denial of Service (DOS) attack, flow
   monitoring can allow detection of unusual load situations or
   suspicious flows. In a second step, flow analysis can be performed in
   order to gather information about the attacking flows, and for
   deriving a defense strategy.

   Intrusion detection is a potentially more demanding application which
   would not only look at specific characteristics of flows, but that
   may also use a stateful packet flow analysis for detecting specific,
   suspicious activities, or unusually frequent activities. Such
   activities may be characterized by specific communication patterns,
   detectable by characteristic sequences of certain packet types.

3.5

3.4.  QoS Monitoring

   QoS monitoring is the non-intrusive (passive) measurement of quality
   parameters for single flows or traffic aggregates. In contrast to
   intrusive (active) measurements, non-intrusive measurements utilize
   the existing traffic in the network for QoS analysis. Since no test
   traffic is sent, non-intrusive measurements can only be applied in
   situations where the traffic of interest is already present in the
   network. One example application is the validation of QoS parameters
   negotiated in a service level specification (SLS).

   Non-intrusive measurements cannot provide the kind of controllable
   experiments that can be achieved with active measurements. On the
   other hand non-intrusive measurements do not suffer from undesired
   side effects caused by sending test traffic (e.g. additional load,



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   potential differences in treatment of test traffic and real customer
   traffic)
   traffic).

   QoS monitoring often requires the correlation of data from multiple
   measurement instances  (e.g. for measuring one-way metrics). This
   requires proper clock synchronization of the involved measurement
   instances. For some measurements packet events at the different
   measurement points must be correlated. For this, the provisioning of
   post-processing functions (e.g. the generation of packet IDs) at the
   measurement instances would be useful. Furthermore, QoS monitoring
   can lead to a huge amount of measurement result data. Therefore it
   would highly benefit from mechanisms to reduce the measurement data,
   like aggregation of results and flow sampling.



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   Please note that not all requirements for QoS monitoring are covered
   by the IPFIX requirements specified in the following sections. The
   IPFIX requirements are targeted at per flow information including
   summaries of per-packet properties for packets within a flow, but not
   per-packet information itself. For example jitter measurement
   requires timestamping each packet and reporting of all timestamps of
   a flow, but the IPFIX requirements only cover timestamps of first and
   last packet of a flow.

4.  Distinguishing Flows

   Packets are mapped to flows by evaluating their properties. Packets
   with common properties are considered to belong to the same flow. A
   packet showing at least one difference in the set of properties is
   considered to belong to a different flow.

   The following subsections list a set of properties which a metering
   process MUST, SHOULD, or MAY be able to evaluate for mapping packets
   to flows. Please note that requiring the ability to evaluate a
   certain property does not imply that this property must be evaluated
   for each packet.

   In other words, compliant with meeting the IPFIX requirements means that the
   metering process in general must be able, via its configuration, to
   somehow support to distinguish flows via all the MUST fields, even if
   in certain circumstance/for certain applications, only a subset of
   the MUST fields is needed and only a subset of the MUST fields is
   effectively used to distinguish flows.

   Which combination of properties is evaluated used for distinguishing a flow in
   a particular measurement and how these properties are evaluated
   depends on the configuration of the IPFIX device. metering process. The configured
   choice of evaluated properties strongly depends on the environment
   and purpose of the measurement and on the information required by the
   collector.

   For specific deployments, only a subset of the REQUIRED properties
   listed below could can be used to distinguish flows, for example in order
   to aggregate the flow records and reduce the number of flow records
   exported. On the other hand, some other deployments will require to
   distinguish
   distinguishing flows by some extra parameters, like for example the
   TTL field of the IP header or the BGP Autonomous Systems.




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4.1.  Interfaces

   The metering process MUST be able to separate flows by the incoming
   interface or by the outgoing interface or by both of them.





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4.2.  IP Header Fields

   The metering process MUST, SHOULD, or MAY be able to separate flows
   by the following fields of the IP header as indicated.

      1. source IP address (MUST)

      2. destination IP address (MUST)

      3. transport protocol type (TCP,UDP,ICMP,...) (MUST)

      4. IP version number (SHOULD)
         This requirement only applies if the the observation point is
         located at a device that is supporting more than one version of
         IP.

   For source address and destination address address, separating by full match
   MUST be supported as well as separation by a partial match (for
   example subnet masking).

4.3.  Transport Header Fields

   The metering process MUST be able to separate flows by the port
   numbers of the transport header in case of TCP or UDP being used as
   transport protocol. Both, source and destination port number MUST be
   supported for distinguishing flows, individually as well as in
   combination.

4.4.  MPLS Label

   If the metering process supports observation point is located at a device supporting
   Multiprotocol Label Switching (MPLS, see [RFC3031]), [RFC3031]) then the measuring device metering
   process MUST be able to separate flows by the MPLS label.

4.5.  DiffServ Code Point

   If the IPFIX observation point is located at a device supports supporting
   Differentiated Services (DiffServ) then the metering process MUST be
   able to separate flows by the DiffServ Code Point (DSCP, see
   [RFC2474]).











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4.6.  Header Compression and Encryption

   If header compression or encryption is used, the metering process
   might not be able to access all header fields. In such a case only For packets with
   compressed or encrypted headers, the requirements stated in this
   section 4 MUST be met for observation points at end points of header
   compression or of packet
   encryption are expected encryption, but they do not need to meet be met
   for observation points between the requirements stated in this
   section 4. end points.



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5.  Metering Process

   The following are requirements for the metering process. All
   measurements MUST be conducted from the point of view of the
   observation point.

5.1.  Reliability

   The metering process MUST either be reliable or missing reliability
   MUST be known and indicated. The metering process is reliable, reliable if each
   packet passing the observation point is measured according to the
   configuration of the metering process. If, e.g. due to some overload,
   not all passing packets can be included into the metering process,
   then the metering process MUST be able to detect this failure and to
   report about it.

5.2.  Sampling

   The metering process MAY support measuring traffic by packet
   sampling. If

   Sampling describes the systematic or random selection of a subset of
   elements (the sample) out of a set of elements (the parent
   population). Usually the purpose of applying sampling techniques is supported
   to estimate a parameter of the sampling method and its
   parameters MUST be well defined. If sampling parameters are parent population by using only the
   elements of the subset. Sampling techniques can be applied for
   instance to select a subset of packets out of all packets of a flow
   or to select a subset of flows out of all flows on a link.  Sampling
   methods differ in their sampling strategy (e.g. systematic or random)
   and in the event that triggers the selection of an element. The
   selection of one packet can for instance be triggered by its arrival
   time (time-based sampling), by its position in the flow (count-based
   sampling) or by the packet content (content-based sampling).

   The metering process MAY support measuring traffic by packet
   sampling. If sampling is supported the sampling configuration MUST be
   well defined. The sampling configuration includes the sampling method
   and all its parameters.

   If the sampling configuration is changed during operation, this the new
   sampling configuration with its parameters MUST be indicated to all
   collectors receiving the affected flow records.

   In case of any change in the sampling configuration, all flow records
   metered by the previous sampling configuration MUST be terminated and
   exported according to the export configuration. The metering process
   MUST NOT merge the flow records generated with the new sampling
   configuration with the flow records generated with the previous
   sampling configuration.






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5.3.  Overload Behavior

   In case of an overload, e. g. for example lack of memory or processing
   power, the metering process MAY change in order to cope with the lack
   of resources. Possible reactions include:

      -  Reduce the number of flow accounts. flows to be measured. This can be achieved
         by more coarse grained flow measurement or by a restriction of
         the flow accounts to a subset of the set of original ones.

      -  Switch to sampling packets before they are processed by the
        meter
         metering process or - if sampling is already performed - reduce
         the sampling rate.

      -  Stop metering.

      -  Reducing the resource usage of competing processes on the same
         device.  Example: reducing the packet forwarding throughput

   Overload behavior is not restricted to the three four options listed



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   But in any case, case the overload behavior has an impact on the metering
   process or the export process, the overload behavior MUST be clearly
   defined and the collector MUST be able to distinguish the flow
   records exported before and after the metering process behavior change.

   For example in the
   change: In case of switching to sampling, any change of the collector meter's behavior, all flow
   records metered by the previous behavior MUST be able terminated and
   exported according to distinguish the export configuration. The metering process
   MUST not merge the flow records generated with sampling from the new behavior with
   the flow records generated without sampling and with the sampling method
   and all its parameters MUST be known or indicated. previous behavior.

5.4.  Timestamps

   The metering process MUST be able to generate a timestamp for each
   observed packet. Please note that section 5.1 requires to offer
   reporting a timestamp timestamps for the
   first and the last observed packet of a flow. Therefore, the metering process The timestamp
   resolution MUST be able to store at least
   two timestamps per flow. the one of the sysUpTime [RFC1213], which
   is one centisecond.

5.5.  Time Synchronization

   Different metering process(es)

   Metering processes and collector(s) collectors SHOULD be time
   synchronized between time-synchronized with
   each other. Using NTP or GPS are possible ways of achieving this. Selecting and deploying
   However selecting a method for time synchronization is not in the
   scope of IPFIX. this document.

5.6.  Timeout

   The metering process MUST be able to detect flow timeout. A flow is
   considered to be timed out if no packet of this flow has been
   observed for a given timeout interval. The metering process MAY
   support means for detecting the end of a flow before a time out


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   occurs, for example by detecting the FIN or RST bits in a TCP
   connection. The procedure for detecting a flow timeout MUST be
   clearly defined.

5.7.  Ignore Port Copy

   The metering process MAY be able to ignore packets which are
   generated by a port copy function acting at the same device. device where the
   observation point of a flow is located.


6.  Data Export

   The following are requirements for exporting measured flow data out
   of the IPFIX device. exporter. Beside requirements on the data transfer, we
   separate requirements concerning the information model from
   requirements concerning the data model. Furthermore, we list
   requirements on reporting times and events and on anonymization of
   records.




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6.1.  Information Model

   The information model for the flow information export is the list of
   attributes of a flow to be contained in the report (including the
   semantics of the attributes).

   This section lists attributes an export process MUST or MAY be able
   to report. This does not imply that a each exported flow records MUST
   contain all REQUIRED attributes, but attributes. But it implies that it MUST be
   possible to configure the device export process in a way that the
   information contained in all of the REQUIRED attributes are
   contained in the flow records for of each measured flow.
   exported flow is transmitted from the export process to the receiving
   collecting process(es).

   In other words, compliant with meeting the IPFIX requirements means that the box export
   process in general must be able, via its configuration, to somehow
   support to report all the MUST fields, even if in certain circumstance/for
   circumstance or for certain applications, only a subset of the MUST
   fields is needed and only a subset of the MUST fields is effectively
   reported.

   Beyond that, the device export process might offer to report also further
   attributes not mentioned here. A particular flow record may contain
   some of the "REQUIRED" attributes as well as some additional ones,
   for example covering future technologies.

   This document does not impose that the following attributes would
   reported for every single flow records, especially for repetitive
   attributes. For example, if the observation point is the incoming
   packet stream at IP interface with the ifIndex value 3, then this


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   observation point does not have to be exported as part of every
   single flow record. Exporting it just once might give sufficient
   information to the collecting process.

   The measuring device export process MUST be able to report the following attributes
   for each measured flow:

      1. IP version number
         This requirement only applies if the device observation point is
         located at a device supporting more than one version of IP.
      2. source IP address
      3. destination IP address
      4. transport IP protocol type (TCP,UDP,ICMP,...)
      5. source TCP/UDP port number
      6. destination TCP/UDP port number
      7. packet counter
         If a packet is fragmented, each fragment input interface (ifIndex)
         This requirement does not apply if the observation point is counted as
         located at a probe device.
      8. output interface (ifIndex)
         This requirement does not apply if the observation point is
         located at a probe device. This requirement does not apply in
         case of multicast flow records.
      9. packet counter
         If a packet is fragmented, each fragment is counted as an
         individual packet.
      8.
     10. byte counter
      9.
         Which bytes of a packet are counted MUST be defined exactly.
     11. in case of IPv4: Type of Service
     10. in case of IPv6: Flow Label
     11. if BGP is supported: supported at the observation point: BGP AS# AS number
     12. if MPLS is supported: supported at the observation point: MPLS label
     13. if DiffServ is supported: supported at the observation point: DSCP
     14. timestamp of the first packet observed of the flow
     15. timestamp of the last packet observed of the flow
     16. if sampling is used: sampling method configuration
     17. if sampling is used: sampling parameters
     18. unique identifier of the observation point



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     19.
     18. unique identifier of the export process

   The measuring device export process MAY be able to report the following attributes for
   each measured flow:

     20. Time To Live
     21. IP header flags
     22. TCP header flags
     23. dropped packet counter at the observation point
         If a packet is fragmented, each fragment MUST be counted as an
         individual packet. This requirements does not apply to probes where
         the value of this counter is always zero.
     24. fragmented packet counter
         counter of all packets for which the fragmented bit is set in
         the IP header


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     25. multicast replication factor
         the number of outgoing packets originating from a single
         incoming multicast packet

6.2

6.2.  Data Model

   The data model describes how information is represented in flow
   records.

   The data model MUST be extensible for future attributes to be added.
   Even if a set of attributes is fixed in the flow record, the data
   model MUST provide a way of extending the record by configuration or
   for certain implementations.

   The data model used for exporting flow information MAY be flexible
   concerning the flow attributes contained in flow records. A flexible
   record format would offer the possibility of defining records in a
   flexible (customizable) way regarding the number and type of
   contained attributes.

   The data model MUST be extensible for future attributes to be added.
   Even if a set of attributes is fixed in the flow record, the data
   model MUST provide a way of extending the record by configuration or
   for certain implementations.

   The Data Model SHOULD be independent of the underlying transport
   protocol, i.e. the data transfer.

6.3.  Data Transfer

   Requirements for the data transfer include reliability and security
   requirements. These requirements do not apply to the measuring device export process
   alone, but also to the transport network. Consequently, the export
   process does not necessarily have to guarantee that all requirements
   are met. Particularly if the security requirements are already
   guaranteed by the network used for data transfer, then these
   requirements do not have to be considered anymore by the export
   process. Therefore, these requirements are OPTIONAL for the export
   process, although they may be REQUIRED for the data transfer as
   specified in the appendix.




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6.3.1.  Congestion Awareness

   For the data transfer transfer, a congestion aware protocol MUST be supported.

6.3.2.  Reliability

   Absence of reliability reliability, for example caused by export packet loss or
   export packet reordering, of the data transfer MUST be indicated
   covering packet loss and packet reordering. indicated.

   Please note that if an unreliable transport protocol is used,
   reliability can be provided by higher layers. In such a case only
   lack of overall reliability MUST be indicated. For example reordering
   could be dealt with by adding a sequence number to each packet.

6.3.3. Security

   Confidentiality of transferred



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6.3.3.  Security

   Confidentiality of flow specific data transferred from an export
   process to a collecting process SHOULD be ensured.

   Integrity of transferred IPFIX flow specific data transferred from an export process to
   a collecting process MUST be ensured.

   Authenticity of transferred IPFIX flow specific data transferred from an export process
   to a collecting process MUST be ensured.

   See more about Security in the "Security Considerations" section 10,
   from which the 3 requirements above are deducted.

6.4.  Push and Pull Mode Reporting

   In general, there are two ways of deciding on reporting times: push
   mode and pull mode. In push mode, the export process decides without
   an external trigger on when to send a report on measured flows. In
   pull mode, sending a report is triggered by an explicit request from
   a collector. The measuring device export process MUST support push mode reporting, it
   MAY support pull mode reporting.

6.5.  Regular Reporting Interval

   The export process SHOULD be capable of reporting measured traffic
   data regularly according to a given interval length.

6.6.  Notification on Specific Events

   The export process MAY be capable of sending notifications to a
   consumer of measure data,
   collecting process, if a specific event occurs. Such an event
   might can be
   the arrival of the first packet of a new flow, or the termination of
   a flow after flow timeout.








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6.7.  Anonymization

   The export process MAY be capable of anonymizing source and
   destination IP addresses in flow data before exporting them. It MAY
   support anonymization of port numbers and other fields. Please note
   that anonymization is not originally an application requirement, but
   derived from general requirements for treatment of traffic within a
   network.


7.  Configuration

   The IPFIX device metering process MUST provide a way of configuring the traffic
   measurement and the traffic data export.
   measurement. The following parameters of the metering process SHOULD
   be configurable:


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      1. specification of the observation point, point
         e.g. an interface or a list of interfaces to be monitored.
      2. specifications of flows to be measured metered
      3. flow timeouts

   The following parameters MAY be configurable:

      4. sampling method and parameters, if feature is supported
      5. overload behavior

   The export process MUST provide a way of configuring the data export.
   The following parameters of the export process SHOULD be
   configurable:

      1. reporting data format
         Specifying the reporting data format SHOULD include a selection
         of attributes to be reported for each flow.
      2. the collecting process(es) to which flows are reported
      3. notifications to be sent to the collecting process(es)
      4. flow timeouts

   The following parameters MAY be configurable:

      5. notifications
      6. sampling method and parameters, anonymization
         Only applicable if feature is supported
      7. the export process supports flow anonymization, if feature is supported
         anonymization.

   If configuration is done remotely, the IPFIX device SHOULD support security of the configuration
   SHOULD be supported including confidentiality, integrity and
   authenticity. The means used for remote configuration of IPFIX
   devices are out of the
   scope of this document.


8.  General Requirements

8.1.  Openness

   IPFIX specifications SHOULD be open to future technologies. This
   includes extensibility of configuration of measurement and reporting
   as well as reporting.

   Openness is also required concerning the extensibility of the reporting information model and data
   model.







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   model, as stated in section 6.2.

8.2.  Scalability concerning measuring devices Concerning the Number of Export Processes

   Data collection from hundreds of different IPFIX devices export processes MUST be
   supported. The collector collecting process MUST be able to distinguish several
   hundred
   IPFIX devices export processes by their identifiers.

8.3.  Several Collectors

   The exporting export process MAY be able to export flow information to more
   than one collector. collecting process.



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9. Security  Special Device Considerations

   This document describes is intended to avoid constraining the architecture of
   probes, routers, and other devices hosting observation points,
   metering processes, export processes, or collecting processes.  It
   can be expected that typically observation point, metering process,
   and export process are co-located at a single device.  However, the
   requirements for IP Flow Information Export
   (IPFIX). defined in this document do not exclude devices that
   derive from this configuration. Figure 2 shows some examples.

            +---+     +-----+     +---------+       +---------+
            | E-+->   |  E--+->   |    E----+->   <-+--E   E--+->
            | | |     |  |  |     |   / \   |       |  |   |  |
            | M |     |  M  |     |  M   M  |       |  M   M  |
            | | |     | /|\ |     | /|\ /|\ |       | /|\ /|\ |
            | O |     | OOO |     | OOO OOO |       | OOO OOO |
            +---+     +-----+     +---------+       +---------+
            Probe      Basic        Complex          Multiple
                       Router       Router           Exporters


          +---+     +---+     +---+
          | E-+->   | E-+->   | E-+------------->---+
          | | |     | | |     | | | +---+         +-+-----+
          +-+-+     | M |     | M | | E-+------->-+-C-M-E-+->
            |       | | |     | | | | | | +---+   +-+-----+
          +-+-+     +-+-+     | O | | M | | E-+->---+
          | | |       |       +---+ | | | | | |
          | M |     +-+-+           | O | | M |
          | | |     | | |           +---+ | | |           +-----+
          | O |     | O |                 | O |        ->-+-C-E-+->
          +---+     +---+                 +---+           +-----+

         Protocol   Remote             Concentrator        Proxy
         Converter  Observation

                      Figure 2: IPFIX-related Devices

   All examples are composed of one or more of the following elements:
   observation point (O), full or partial metering process (M), export
   process (E), collecting process (C). The observation shown in the
   figure are always the most fine-granular ones supported by the
   respective device.

   A very simple device is a probe. It therefore contains on a single observation
   point, a single metering process, and a single export process.

   A basic router extends this structure by multiple observation point.
   Here, the observation point of a flow may be one of the displayed
   most fine-granular observation points, but also states it may be a set of


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   them.

   A more complex router may host more than one metering process, for
   example one per line card. Please note that here, the observation
   point of a single flow cannot exceed the set of most fine-granular
   observation points linked to a single metering process, because only
   the metering process can merge packets observed at different fine-
   granular observation points to a joint flow. An observation point
   containing all most fine-granular observation points of this router
   is not possible with this structure.

   Alternatively, a complex router may host different export processes
   for flow records generated by different metering processes.

   A protocol converter makes use of a metering process that can be
   accessed only by another protocol than the required security features one defined for IPFIX, for
   example the SNMP and the Meter MIB module [RFC2720]. Then the
   exporter receives flow record from a future remote metering process and
   exports these records using the IPFIX protocol. Nevertheless,

   Another choice is remote packet observation. Packet header captured
   at an observation point may be exported as raw data to a device
   hosting metering process and export process.

   An intermediate structure between protocol converter and remote
   observation (not shown in the suggestion of solutions Figure) would be a split metering
   process, for achieving example performing timestamping and sampling at the security properties is out
   device hosting the observation point and performing packet
   classification at another device hosting the export process.

   A concentrator receives flow records via the IPFIX protocol, merges
   them into higher aggregated flows and exports the resulting flows
   again using the IPFIX protocol. Please note that for the final flow
   records the observation point potentially includes all most fine-
   granular observation points of scope all first level devices.  The metering
   process of this
   document the final flow records is composed by the (partial)
   metering processes at the first level devices and will the partial
   metering process at the concentrator.

   Finally, a very simple IPFIX-related device is a proxy. It just
   receives flow records using the IPFIX protocol and sends them further
   using the same protocol. A proxy might be part of future useful for traversing
   firewalls or other gateways.


10.  Security Considerations

   An IPFIX documents protocol must be capable to transport data over the public
   Internet. Therefore it cannot be excluded that specify an attacker captures
   or modifies packets or inserts additional packets.


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   This section describes security requirements for IPFIX. Like other
   requirements, the security requirements differ for among the considered
   applications. The incentive to modify collected data for accounting
   or intrusion detection for instance is usually higher than the
   incentive to change data collected for traffic profiling.
   Therefore A detailed
   list of the required security features are listed per application.
   Furthermore, the security requirements also differ with regard to the
   environment application can be found
   in which an IPFIX protocol is used (e.g. intra- or inter-
   domain). Some the appendix.

   The suggestion of these issues are concrete solutions for achieving the required
   security properties should be part of the an IPFIX architecture and
   with this
   protocol is out of scope of this document. Therefore this document also
   tries to consider security threats that can only occur in an insecure
   environment (e.g. where it can not be excluded, that an attacker
   might gain access to the network).

   Several security hazards also occur if the IPFIX device is configured
   remotely (e.g. access to the measurement process, forgery of
   configuration information, etc.). Nevertheless, this document
   specifies only what parameters SHOULD or MAY be configurable Also methods for remote
   configuration of the
   IPFIX device. It does not deal with requirements for a protocol metering processes and export processes out of
   scope. Therefore, threats that are caused by data exchange for
   measurement configuration. Therefore security considerations
   regarding the measurement remote
   configuration are out of scope of this
   document. not considered here.

   The following potential security hazards for an IPFIX protocol can be
   identified:

       - Disclosure disclosure of IP flow information information, forgery of flow
   records, and Denial of Service (DoS) attacks.

10.1.  Disclosure of Flow Information Data

   The content of data
         It may exchanged by an IPFIX protocol (for example IPFIX
   flow records) should be required to keep measurement records kept confidential



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   parties (export process and collecting process). Observation of IP IPFIX
   flow
         information data records gives an attacker information about the active flows in
   the network, communication endpoints and traffic patterns. This
   information can not cannot only be used to spy out user behavior but also to
   plan and conceal future attacks. Therefore Therefore, the requirements document recommends to ensure the
   specified in section 6.3.3. include confidentiality of the
   transferred data. This can be done achieved for instance by encryption.

         Furthermore, features for anonymization may be provided by the
         future IPFIX protocol. With this communication endpoints can be
         kept confidential. Anonymization is also a useful feature to
         allow measurements (e.g. by a third party) without violating
         privacy protection.

       -

10.2.  Forgery of exported IP Flow Records

   If flow information data
         Especially for applications like records are used in accounting or intrusion
         detection and security applications,
   there are potentially strong incentives (e.g. to forge exported IPFIX flow
   records (for example to save money or prevent the detection of an attack) to forge exported IP flow
         information records.
   attack). This can be done either by altering data flow records on the path
   or by exporting injecting forged flow records from a device that pretends pretend to be originated by
   the IPFIX device. original export process. In order to make the an IPFIX protocol
   resistant against such attacks this document requires to ensure
         authenticity attacks, authentication and integrity of the data for the IPFIX data
         transfer. must be
   provided, as specified in section 6.3.3.

   Special caution is required if security applications rely on
         IPFIX data flow
   measurements. With forgery of exported IP forged flow information data records it is possible to trick on
   security applications. With this it can
         be It is for instance possible to pretend that a
   DoS attack happens without even launching a real attack.

       -






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10.3.  Denial of Service (DoS) attacks Attacks

   DoS attacks on routers or other middleboxes that have the IPFIX
   protocol implemented would also affect the IPFIX protocol and impair
   the sending of IPFIX records. Nevertheless, since such hazards are
   not induced specifically by the IPFIX protocol the prevention of such
   attacks is out of scope of this document.

   Nevertheless IPFIX itself also causes the following potential hazards for DoS
   attacks. It is always possible to overload the IPFIX device if
         it expects the reception of traffic. For IPFIX this can occur
         in two cases. First, if the protocol supports the pull mode
         (which is one option in this document) and expects requests.
         Secondly, if data is expected for remote measurement
         configuration. The first case could be prevented by ensuring
         authenticity for IPFIX requests. The second case should be
         addressed for the specification of an IPFIX remote



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         configuration mechanism and therefore is out of scope of this
         document.

         Also IPFIX collectors can become target of an DoS attack. This
         can be done by sending IPFIX data from a malicious device that
         pretends to be an IPFIX device. This can be  prevented by
         ensuring authenticity of IPFIX data as stated in this document.
         It is also possible  All processes that collectors are flooded with IPFIX
         record from an authorized IPFIX devices for which expect the
         configuration was altered. Furthermore, malicious configuration
         or forgery of exported data can cause a loss or re-direction of
         flow information (e.g. if destination addresses for flow
         records are modified). This can lead to a disruption reception of upper
         layer services (accounting, intrusion detection, etc.)  due to
         lack traffic can be
   target of a DoS attack. With the IPFIX records. This export process this is only
   the case if it supports the pull mode (which can be prevented by controlling
         configuration access an optional
   feature of the future IPFIX protocol according to this document). The
   collecting process always expects data and therefore can be flooded
   by ensuring the integrity of exported
         data.


10. forged flow records.


11.  Acknowledgments

   We like to thank all the people contributing to the requirements
   discussion on the mailing list for a lot of valuable comments.


11.


12.  References

   [MIDBOXTAX]

[RFC2026]   S. Bradner, "The Internet Standards Process -- Revision 3",
            RFC 2026, October 1996.

[RFC3234]   B. Carpenter, "Middleboxes: taxonomy and issues", RFC 3234,
            February 2002.

[RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", RFC 2119, March 1997.

[RFC2702]   D. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, J. McManus,
            "Requirements for Traffic Engineering Over MPLS", RFC 2702,
            September 1999.

[RFC3031]   E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label
            Switching Architecture", RFC 3031, January 2001.

[RFC2474]   K. Nichols, S. Blake, F. Baker, D. Black, "Definition of the
            Differentiated Services Field (DS Field) in the IPv4 and
            IPv6 Headers", RFC 2474, December 1998.

   [RFC2702] D. Awduche, J. Malcolm, J. Agogbua,

[RFC1213]   K. McCloghrie, M. O'Dell, J. McManus,
              "Requirements for Traffic Engineering Over MPLS",
              RFC 2702, September 1999.

   [RFC2274] U. Blumenthal, B. Wijnen "User-based Security Model (USM) Rose. "Management Information Base for version 3 of the Simple
            Network Management Protocol
             (SNMPv3), of TCP/IP-based internets: MIB-II", RFC 2274, January 1998.
            1213, March 1991.




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12. List of Authors


[RFC2720]   N. Brownlee. "Traffic Flow Measurement: Meter MIB", RFC
            2720, October 1999.


13.  Authors' Addresses

     Juergen Quittek
     NEC Europe Ltd., Network Laboratories
     Adenauerplatz 6
     69115 Heidelberg
     Germany

     Phone: +49 6221 90511-15
     EMail: quittek@ccrle.nec.de


     Tanja Zseby
     Fraunhofer Institute for Open Communication Systems (FOKUS)
     Kaiserin-Augusta-Allee 31
     10589 Berlin
     Germany

     Phone: +49 30 3463 7153
     Email: zseby@fokus.fhg.de


     Benoit Claise
     Cisco Systems
     De Kleetlaan 6a b1
     1831 Diegem
     Belgium

     Phone: +32 2 704 5622
     Email: bclaise@cisco.com


     Sebastian Zander
     Fraunhofer Institute for Open Communication Systems (FOKUS)
     Kaiserin-Augusta-Allee 31
     10589 Berlin
     Germany

     Phone: +49 30 3463 7287
     Email: zander@fokus.fhg.de


     Georg Carle
     Fraunhofer Institute for Open Communication Systems (FOKUS)
     Kaiserin-Augusta-Allee 31
     10589 Berlin


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     Germany

     Phone: +49 30 3463 7149
     Email: carle@fokus.fhg.de


   Sebastian Zander
   Fraunhofer Institute


     K.C. Norseth
     Consultant
     934 S. Palos Verdes Dr.
     Kaysville, Utah 84037 USA

     Phone: 801.546.3316
     Email: kcn@norseth.com


14.  Full Copyright Statement

   Copyright (C) The Internet Society (2001). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for Open Communication Systems (FOKUS)
   Kaiserin-Augusta-Allee 31
   10589 Berlin
   Germany

   Phone: +49 30 3463 7287
   Email: zander@fokus.fhg.de











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   developing Internet Draft             IPFIX Requirements                 March 2002


   Benoit Claise
   Cisco Systems
   De Kleetlaan 6a b1
   1831 Diegem
   Belgium

   Phone: +32 2 704 5622
   Email: bclaise@cisco.com


   K.C. Norseth
   Enterasys Networks
   2691 S. Decker Lake Lane
   Salt Lake City, Utah 84119
   USA

   Phone: +1 801 887 9823
   Email: knorseth@enterasys.com standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.










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Appendix: Derivation of Requirements form Target from Applications

   The following table documents, how the requirements stated in
   sections 3-7 are derived from requirements of the applications listed
   in section 2.

   Used abbreviations:
      M = MUST
      S = SHOULD
      O = MAY (OPTIONAL)
      - = DONT CARE

   -----------------------------------------------------------------------.
      IPFIX                                                               |
   ----------------------------------------------------------------.      |
   E: QoS Monitoring                                               |      |
   ----------------------------------------------------------.     |      |
   D: Attack/Intrusion Detection                             |     |      |
   ----------------------------------------------------.     |     |      |
   C: Traffic Engineering                              |     |     |      |
   ----------------------------------------------.     |     |     |      |
   B: Traffic Profiling                          |     |     |     |      |
   ----------------------------------------.     |     |     |     |      |
   A: Usage-based Accounting               |     |     |     |     |      |
   ----------------------------------.     |     |     |     |     |      |
                                     |     |     |     |     |     |      |
   | Sect. |    Requirement          |  A  |  B  |  C  |  D  |  E  | IPFIX|
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.    | DISTINGUISHING FLOWS                                         |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.    | Combination of          |  M  |  M  |  M  |  M  |  M  |  M   |
   |       | required attributes     |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.1.  | in/out IF               |  S  |  M  |  M  |  S  |  S  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.2.  | src/dst address         |  M  |  M  |  M  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.2.  | Masking of IP adresses  |  M  |  M  |  M  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.2.  | transport protocol      |  M  |  M  |  -  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.2.  | version field           |  -  |  S  |  S  |  O  |  O  |  S   |
   |       |                         |     |     | (b) |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.3.  | src/dst port            |  M  |  M  |  -  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|






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   | Sect. |    Requirement          |  A  |  B  |  C  |  D  |  E  | IPFIX|
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.4.  | MPLS label (a)          |  S  |  S  |  M  |  O  |  S  |  M   |
   |       |                         |     |     | (c) |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 4.5.  | DSCP (a)                |  M  |  S  |  M  |  O  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.    | METERING PROCESS                                             |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.1.  | Reliability             |  M  |  S  |  S  |  S  |  S  |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+  M   |
   | 5.1.  | Indication of           |  -  |  M  |  M  |  M  |  M  |      |
   |       | missing reliability     |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.2.  | Sampling (g)            |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.2. 5.3.  | Dynamic sampling Overload Behavior       |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.4.  | Timestamping at Timestamps              |  M  |  O  |  O  |  S  |  M  |  M   |
   |       | measurement device      |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.5.  | Time synchronization    |  S  |  S  |  S  |  S  |  S  |  S   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.6.  | Flow timeout            |  M  |  S  |  -  |  O  |  O  |  M   |
   |       |                         | (d) |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 5.7.  | Ignore port copy        |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.    | DATA EXPORT                                                  |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | INFORMATION MODEL                                            |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | IP Version              |  -  |  M  |  M  |  O  |  O  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | src/dst address         |  M  |  M  |  M  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | transport protocol      |  M  |  M  |  -  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | src/dst transport port            |  M  |  M  |  -  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Packet counter (h)      |  S  |  M  |  M  |  S  |  S  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Byte counter            |  M  |  M  |  M  |  S  |  S  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|









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   | Sect. |    Requirement          |  A  |  B  |  C  |  D  |  E  | IPFIX|
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Dropped Packet          |  O  |  M  |  M  |  S  |  M  |  M   |
   |       | Counter (h,i)           |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | ToS Byte                |  M  |  S  |  M  |  O  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Flow Label              |  M  |  S  |  M  |  O  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | BGP AS#                 |  -  |  S  |  M  |  -  |  -  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | MPLS label (a)          |  S  |  S  |  M  |  O  |  S  |  M   |
   |       |                         |     |     | (c) |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | DSCP (a)                |  M  |  S  |  M  |  O  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Timestamps for          |  M  |  O  |  O  |  S  |  S  |  M   |
   |       | first/last packet       |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Sampling methods configuration  |  M  |  M  |  M  |  M  |  M  |  M   |
   |       | & parameters (k)        |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | observation point       |  M  |  M  |  M  |  M  |  M  |  M   |
   |       | identifier              |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | measuring device export process          |  M  |  M  |  M  |  M  |  M  |  M   |
   |       | identity identifier              |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | TTL                     |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | IP header flags         |  -  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | TCP header flags        |  -  |  O  |  O  |  O  |  -  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Fragment counter        |  -  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Multicast               |  O  |  O  |  O  |  -  |  -  |  O   |
   |       | replication factor      |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.1.  | Flow configuration      |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.2.  | DATA MODEL                                                   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.2.  | Flexibility             |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.2.  | Extensibility           |  M  |  M  |  M  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|








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   | Sect. |    Requirement          |  A  |  B  |  C  |  D  |  E  | IPFIX|
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.3.  | DATA TRANSFER                                                |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.3.1.| Congestion aware        |  M  |  M  |  M  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.3.2.| Reliability             |  M  |  S  |  S  |  S  |  S  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.3.3.| Confidentiality         |  S  |  S  |  S  |  S  |  S  |  S   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.3.4.| Integrity               |  M  |  M  |  M  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.3.5.| Authenticity            |  M  |  M  |  M  |  M  |  M  |  M   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.4.  | REPORTING TIMES                                              |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.4.  | Push mode               |  M  |  O  |  O  |  M  |  S  |  M   |
   |       |                         |     | (e) | (e) |     |(e,f)|      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.4.  | Pull mode               |  O  |  O  |  O  |  O  |  O  |  O   |
   |       |                         |     | (e) | (e) |     | (e) |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.4.1.| Regular Interval        |  S  |  S  |  S  |  S  |  S  |  S   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.6.  | Notifications           |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 6.7.  | Anonymization           |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | CONFIGURATION                                                |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Measurement      |  M  |  M  |  M  |  M  |  M  |  M   |
   |       | & Data Export           |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Observation Point|  S  |  S  |  S  |  S  |  S  |  S   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Flow             |  S  |  S  |  S  |  S  |  S  |  S   |
   |       | Specifications          |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Report Flow Timeouts    |  S  |  S  |  S  |  S  |  S  O  |  S   |
   |       | Data Format             |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Flow Timeouts Sampling         |  S  O  |  S  O  |  S  O  |  S  O  |  O  |  S  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|










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   | Sect. |    Requirement          |  A  |  B  |  C  |  D  |  E  | IPFIX|
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Report           |  O  S  |  O  S  |  O  S  |  O  S  |  O  S  |  O  S   |
   |       | Notifications Data Format             |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Sampling                  |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.       | Config Anonymization Notifications           |  O     |  O     |  O     |  O     |  O     |  O      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 7.    | Config Security Anonymization    |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 8.    | GENERAL REQUIREMENTS                                         |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 8.1.  | Openness                |  S  |  S  |  S  |  S  |  S  |  S   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 8.2.  | Scalability:            |     |     |     |     |     |      |
   |       | data collection         |  M  |  S  |  M  |  O  |  S  |  M   |
   |       | from hundreds of        |     |     |     |     |     |      |
   |       | measurement devices     |     |     |     |     |     |      |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|
   | 8.3.  | Several Collectors      |  O  |  O  |  O  |  O  |  O  |  O   |
   |-------+-------------------------+-----+-----+-----+-----+-----+------|

   Remarks:
     (a) If feature is supported.
     (b) The differentiation of IPv4 and IPv6 is for TE of importance.
         So we tended to make this a MUST. Nevertheless, a SHOULD seems
         to be sufficient to perform most TE tasks and allows us to have
         a SHOULD for IPFIX instead of a MUST.
     (c) For TE in an MPLS network the label is essential. Therefore a
         MUST is given here leading to a MUST in IPFIX.
     (d) Precise time-based accounting requires reaction to a flow
         timeout.
     (e) Either push or pull has to be supported.
     (f) Required, in order to immediately report drop indications for
         SLA validation.
     (g) If sampling is supported the parameters and methods and parameters MUST be
         well defined.
     (h) If a packet is fragmented, each fragment is counted as an
         individual packet.
     (i) Only if measurement is done on data path i.e. has access to
         forwarding decision.
     (k) If sampling is used.











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----