Network Working Group T. Dietz

Network Working Group T. Dietz
Request for Comments: 5477 NEC Europe Ltd.
Category: Standards Track B. Claise
P. Aitken
Cisco Systems, Inc.
F. Dressler
University of Erlangen-Nuremberg
G. Carle
Technical University of Munich
March 2009

Information Model for Packet Sampling Exports

Status of This Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (c) 2009 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 in effect on the date of
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Please review these documents carefully, as they describe your rights
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Contributions published or made publicly available before November
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Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
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not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.

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RFC 5477 PSAMP Information Model March 2009

Abstract

This memo defines an information model for the Packet SAMPling
(PSAMP) protocol. It is used by the PSAMP protocol for encoding
sampled packet data and information related to the Sampling process.
As the PSAMP protocol is based on the IP Flow Information eXport
(IPFIX) protocol, this information model is an extension to the IPFIX
information model.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. PSAMP Documents Overview . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Conventions Used in This Document . . . . . . . . . . . . 5
4. Relationship between PSAMP and IPFIX . . . . . . . . . . . . . 5
5. Properties of a PSAMP Information Element . . . . . . . . . . 5
6. Type Space . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Overloading Information Elements . . . . . . . . . . . . . . . 6
8. The PSAMP Information Elements . . . . . . . . . . . . . . . . 6
8.1. Identifiers (301-303) . . . . . . . . . . . . . . . . . . 7
8.1.1. selectionSequenceId . . . . . . . . . . . . . . . . . 7
8.1.2. selectorId . . . . . . . . . . . . . . . . . . . . . . 8
8.1.3. informationElementId . . . . . . . . . . . . . . . . . 8
8.2. Sampling Configuration (304-311) . . . . . . . . . . . . . 9
8.2.1. selectorAlgorithm . . . . . . . . . . . . . . . . . . 9
8.2.2. samplingPacketInterval . . . . . . . . . . . . . . . . 11
8.2.3. samplingPacketSpace . . . . . . . . . . . . . . . . . 11
8.2.4. samplingTimeInterval . . . . . . . . . . . . . . . . . 12
8.2.5. samplingTimeSpace . . . . . . . . . . . . . . . . . . 12
8.2.6. samplingSize . . . . . . . . . . . . . . . . . . . . . 13
8.2.7. samplingPopulation . . . . . . . . . . . . . . . . . . 13
8.2.8. samplingProbability . . . . . . . . . . . . . . . . . 13
8.3. Hash Configuration (326-334) . . . . . . . . . . . . . . . 14
8.3.1. digestHashValue . . . . . . . . . . . . . . . . . . . 14
8.3.2. hashIPPayloadOffset . . . . . . . . . . . . . . . . . 15
8.3.3. hashIPPayloadSize . . . . . . . . . . . . . . . . . . 15
8.3.4. hashOutputRangeMin . . . . . . . . . . . . . . . . . . 15
8.3.5. hashOutputRangeMax . . . . . . . . . . . . . . . . . . 16
8.3.6. hashSelectedRangeMin . . . . . . . . . . . . . . . . . 16
8.3.7. hashSelectedRangeMax . . . . . . . . . . . . . . . . . 16
8.3.8. hashDigestOutput . . . . . . . . . . . . . . . . . . . 17
8.3.9. hashInitialiserValue . . . . . . . . . . . . . . . . . 17
8.4. Timestamps (322-325) . . . . . . . . . . . . . . . . . . . 18
8.4.1. observationTimeSeconds . . . . . . . . . . . . . . . . 18
8.4.2. observationTimeMilliseconds . . . . . . . . . . . . . 18
8.4.3. observationTimeMicroseconds . . . . . . . . . . . . . 19
8.4.4. observationTimeNanoseconds . . . . . . . . . . . . . . 19

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8.5. Packet Data (313-314, 316-317) . . . . . . . . . . . . . . 19
8.5.1. ipHeaderPacketSection . . . . . . . . . . . . . . . . 20
8.5.2. ipPayloadPacketSection . . . . . . . . . . . . . . . . 20
8.5.3. mplsLabelStackSection . . . . . . . . . . . . . . . . 21
8.5.4. mplsPayloadPacketSection . . . . . . . . . . . . . . . 21
8.6. Statistics (318-321, 336-338) . . . . . . . . . . . . . . 22
8.6.1. selectorIdTotalPktsObserved . . . . . . . . . . . . . 22
8.6.2. selectorIdTotalPktsSelected . . . . . . . . . . . . . 23
8.6.3. absoluteError . . . . . . . . . . . . . . . . . . . . 23
8.6.4. relativeError . . . . . . . . . . . . . . . . . . . . 24
8.6.5. upperCILimit . . . . . . . . . . . . . . . . . . . . . 24
8.6.6. lowerCILimit . . . . . . . . . . . . . . . . . . . . . 25
8.6.7. confidenceLevel . . . . . . . . . . . . . . . . . . . 26
9. Security Considerations . . . . . . . . . . . . . . . . . . . 26
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
10.1. Related Considerations . . . . . . . . . . . . . . . . . . 27
10.2. PSAMP-Related Considerations . . . . . . . . . . . . . . . 27
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27
11.1. Normative References . . . . . . . . . . . . . . . . . . . 27
11.2. Informative References . . . . . . . . . . . . . . . . . . 28
Appendix A. Formal Specification of PSAMP Information Elements . 29

1. Introduction

Packet Sampling techniques are required for various measurement
scenarios. The Packet Sampling (PSAMP) protocol provides mechanisms
for packet selection using different Filtering and Sampling
techniques. A standardized way for the export and storage of the
Information Elements defined in Section 8 is required. The
definition of the PSAMP information and data model is based on the
IPFIX information model [RFC5102]. The PSAMP protocol document
[RFC5476] specifies how to use the IPFIX protocol in the PSAMP
context.

This document examines the IPFIX information model [RFC5102] and
extends it to meet the PSAMP requirements. Therefore, the structure
of this document is strongly based on the IPFIX document. It
complements the PSAMP protocol specification by providing an
appropriate PSAMP information model. The main part of this document,
Section 8, defines the list of Information Elements to be transmitted
by the PSAMP protocol. Sections 5 and 6 describe the data types and
Information Element properties used within this document and their
relationship to the IPFIX information model.

Although the PSAMP charter specified no requirements for measuring
packet errors (such as drops, malformed, etc.), and this document
does not cover such data, if there is need for collecting and
exporting packet error information, the appropriate Information

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Elements can be requested from IANA, and exported with the PSAMP
protocol.

The main body of Section 8 was generated from an XML document. The
XML-based specification of the PSAMP Information Elements can be used
for automatically checking syntactical correctness of the
specification. Furthermore it can be used -- in combination with the
IPFIX information model -- for automated code generation. The
resulting code can be used in PSAMP protocol implementations to deal
with processing PSAMP information elements.

For that reason, the XML document that served as the source for
Section 8 is attached to this document in Appendix A.

Note that although partially generated from the attached XML
documents, the main body of this document is normative while the
appendix is informational.

2. PSAMP Documents Overview

This document is one out of a series of documents from the PSAMP
group.

[RFC5474]: "A Framework for Packet Selection and Reporting" describes
the PSAMP framework for network elements to select subsets of packets
by statistical and other methods, and to export a stream of reports
on the selected packets to a Collector.

[RFC5475]: "Sampling and Filtering Techniques for IP Packet
Selection" describes the set of packet selection techniques supported
by PSAMP.

[RFC5476]: "Packet Sampling (PSAMP) Protocol Specifications"
specifies the export of packet information from a PSAMP Exporting
Process to a PSAMP Collecting Process.

RFC 5477 (this document): "Information Model for Packet Sampling
Exports" defines an information and data model for PSAMP.

3. Terminology

IPFIX-specific terminology used in this document is defined in
Section 2 of [RFC5101]. PSAMP-specific terminology used in this
document is defined in Section 3.2 of [RFC5476]. In this document,
as in [RFC5101] and [RFC5476], the first letter of each IPFIX- and
PSAMP-specific term is capitalized.

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3.1. Conventions Used in This Document

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

4. Relationship between PSAMP and IPFIX

As described in the PSAMP protocol [RFC5476], a PSAMP Report can be
seen as a very special IPFIX Data Record. It represents an IPFIX
Flow containing only a single packet. Therefore, the IPFIX
information model can be used as a basis for PSAMP Reports.

Nevertheless, there are properties required in PSAMP Reports that
cannot be modeled using the current IPFIX information model. This
document describes extensions to the IPFIX information model that
allow the modeling of information and data required by PSAMP.

Some of these extensions allow the export of what may be considered
sensitive information. Refer to the Security Considerations section
for a fuller discussion.

Note that the export of sampled or filtered PSAMP Reports may not
need all the Information Elements defined by the IPFIX information
model [RFC5102], as discussed in Sections 6.2 and 6.3 of the PSAMP
Framework [RFC5474].

5. Properties of a PSAMP Information Element

The PSAMP Information Elements are defined in accordance with
Sections 2.1 to 2.3 of the IPFIX information model [RFC5102] to which
reference should be made for more information. Nevertheless, we
strongly recommend defining the optional "units" property for every
Information Element (if applicable).

The Data Types defined in Section 3.1 of the IPFIX information model
[RFC5102] are also used for the PSAMP Information Elements.

6. Type Space

The PSAMP Information Elements MUST be constructed from the basic
abstract data types and data type semantics described in Section 3 of
the IPFIX information model [RFC5102]. To ensure consistency between
IPFIX and PSAMP, the data types are not repeated in this document.
The encoding of these data types is described in the IPFIX protocol
[RFC5101].

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7. Overloading Information Elements

Information Elements SHOULD NOT be overloaded with multiple meanings
or re-used for multiple purposes. Different Information Elements
SHOULD be allocated for each requirement.

Although the presence of certain other Information Elements allows
the selection method to be inferred, a separate Information Element
is provided for the selectorAlgorithm to include as scope for the
Selector Report Interpretation [RFC5476].

Even if the Information Elements are specified with a specific
selection method (i.e., a specific value of selectorAlgorithm) in
mind, these Information Elements are not restricted to the selection
method and MAY be used for different selection methods in the future.

8. The PSAMP Information Elements

This section describes the Information Elements used by the PSAMP
protocol.

For each Information Element specified in Sections 8.1 - 8.6 below, a
unique identifier is allocated in accordance with Section 4 of the
IPFIX information model [RFC5102]. The assignments are controlled by
IANA as an extension of the IPFIX information model.

The Information Elements specified by the IPFIX information model
[RFC5102] are used by the PSAMP protocol where applicable. To avoid
inconsistencies between the IPFIX and the PSAMP information and data
models, only those Information Elements that are not already
described by the IPFIX information model are defined here.

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Below is the list of additional PSAMP Information Elements:

+-----+----------------------------+-----+----------------------------+
| ID | Name | ID | Name |
+-----+----------------------------+-----+----------------------------+
| 301 | selectionSequenceId | 321 | relativeError |
| 302 | selectorId | 322 | observationTimeSeconds |
| 303 | informationElementId | 323 | observationTimeMilliseconds|
| 304 | selectorAlgorithm | 324 | observationTimeMicroseconds|
| 305 | samplingPacketInterval | 325 | observationTimeNanoseconds |
| 306 | samplingPacketSpace | 326 | digestHashValue |
| 307 | samplingTimeInterval | 327 | hashIPPayloadOffset |
| 308 | samplingTimeSpace | 328 | hashIPPayloadSize |
| 309 | samplingSize | 329 | hashOutputRangeMin |
| 310 | samplingPopulation | 330 | hashOutputRangeMax |
| 311 | samplingProbability | 331 | hashSelectedRangeMin |
| 313 | ipHeaderPacketSection | 332 | hashSelectedRangeMax |
| 314 | ipPayloadPacketSection | 333 | hashDigestOutput |
| 316 | mplsLabelStackSection | 334 | hashInitialiserValue |
| 317 | mplsPayloadPacketSection | 336 | upperCILimit |
| 318 | selectorIdTotalPktsObserved| 337 | lowerCILimit |
| 319 | selectorIdTotalPktsSelected| 338 | confidenceLevel |
| 320 | absoluteError | | |
+-----+----------------------------+-----+----------------------------+

8.1. Identifiers (301-303)

Information Elements in this section serve as identifiers. All of
them have an integral abstract data type and data type semantics
"identifier".

+-----+----------------------------+-----+----------------------------+
| ID | Name | ID | Name |
+-----+----------------------------+-----+----------------------------+
| 301 | selectionSequenceId | 303 | informationElementId |
| 302 | selectorId | | |
+-----+----------------------------+-----+----------------------------+

8.1.1. selectionSequenceId

Description:

From all the packets observed at an Observation Point, a subset of
the packets is selected by a sequence of one or more Selectors.
The selectionSequenceId is a unique value per Observation Domain,
specifying the Observation Point and the sequence of Selectors
through which the packets are selected.

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Abstract Data Type: unsigned64

Data Type Semantics: identifier

ElementId: 301

Status: current

8.1.2. selectorId

Description:

The Selector ID is the unique ID identifying a Primitive Selector.
Each Primitive Selector must have a unique ID in the Observation
Domain.

Abstract Data Type: unsigned16

Data Type Semantics: identifier

ElementId: 302

Status: current

8.1.3. informationElementId

Description:

This Information Element contains the ID of another Information
Element.

Abstract Data Type: unsigned16

Data Type Semantics: identifier

ElementId: 303

Status: current

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8.2. Sampling Configuration (304-311)

Information Elements in this section can be used for describing the
Sampling configuration of a Selection Process.

+-----+----------------------------+-----+----------------------------+
| ID | Name | ID | Name |
+-----+----------------------------+-----+----------------------------+
| 304 | selectorAlgorithm | 308 | samplingTimeSpace |
| 305 | samplingPacketInterval | 309 | samplingSize |
| 306 | samplingPacketSpace | 310 | samplingPopulation |
| 307 | samplingTimeInterval | 311 | samplingProbability |
+-----+----------------------------+-----+----------------------------+

8.2.1. selectorAlgorithm

Description:

This Information Element identifies the packet selection methods
(e.g., Filtering, Sampling) that are applied by the Selection
Process.

Most of these methods have parameters. Further Information
Elements are needed to fully specify packet selection with these
methods and all their parameters.

The methods listed below are defined in [RFC5475]. For their
parameters, Information Elements are defined in the information
model document. The names of these Information Elements are
listed for each method identifier.

Further method identifiers may be added to the list below. It
might be necessary to define new Information Elements to specify
their parameters.

The selectorAlgorithm registry is maintained by IANA. New
assignments for the registry will be administered by IANA and are
subject to Expert Review [RFC5226].

The registry can be updated when specifications of the new
method(s) and any new Information Elements are provided.

The group of experts must double check the selectorAlgorithm
definitions and Information Elements with already defined
selectorAlgorithms and Information Elements for completeness,
accuracy, and redundancy. Those experts will initially be drawn
from the Working Group Chairs and document editors of the IPFIX
and PSAMP Working Groups.

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The following packet selection methods identifiers are defined
here:

+----+------------------------+------------------------+
| ID | Method | Parameters |
+----+------------------------+------------------------+
| 1 | Systematic count-based | samplingPacketInterval |
| | Sampling | samplingPacketSpace |
+----+------------------------+------------------------+
| 2 | Systematic time-based | samplingTimeInterval |
| | Sampling | samplingTimeSpace |
+----+------------------------+------------------------+
| 3 | Random n-out-of-N | samplingSize |
| | Sampling | samplingPopulation |
+----+------------------------+------------------------+
| 4 | Uniform probabilistic | samplingProbability |
| | Sampling | |
+----+------------------------+------------------------+
| 5 | Property Match | no agreed parameters |
| | Filtering | |
+----+------------------------+------------------------+
| Hash-based Filtering | hashInitialiserValue |
+----+------------------------+ hashIPPayloadOffset |
| 6 | using BOB | hashIPPayloadSize |
+----+------------------------+ hashSelectedRangeMin |
| 7 | using IPSX | hashSelectedRangeMax |
+----+------------------------+ hashOutputRangeMin |
| 8 | using CRC | hashOutputRangeMax |
+----+------------------------+------------------------+

There is a broad variety of possible parameters that could be used
for Property match Filtering (5), but currently there are no
agreed parameters specified.

Abstract Data Type: unsigned16

Data Type Semantics: identifier

ElementId: 304

Status: current

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8.2.2. samplingPacketInterval

Description:

This Information Element specifies the number of packets that are
consecutively sampled. A value of 100 means that 100 consecutive
packets are sampled.

For example, this Information Element may be used to describe the
configuration of a systematic count-based Sampling Selector.

Abstract Data Type: unsigned32

Data Type Semantics: quantity

ElementId: 305

Status: current

Units: packets

8.2.3. samplingPacketSpace

Description:

This Information Element specifies the number of packets between
two "samplingPacketInterval"s. A value of 100 means that the next
interval starts 100 packets (which are not sampled) after the
current "samplingPacketInterval" is over.

For example, this Information Element may be used to describe the
configuration of a systematic count-based Sampling Selector.

Abstract Data Type: unsigned32

Data Type Semantics: quantity

ElementId: 306

Status: current

Units: packets

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8.2.4. samplingTimeInterval

Description:

This Information Element specifies the time interval in
microseconds during which all arriving packets are sampled.

For example, this Information Element may be used to describe the
configuration of a systematic time-based Sampling Selector.

Abstract Data Type: unsigned32

Data Type Semantics: quantity

ElementId: 307

Status: current

Units: microseconds

8.2.5. samplingTimeSpace

Description:

This Information Element specifies the time interval in
microseconds between two "samplingTimeInterval"s. A value of 100
means that the next interval starts 100 microseconds (during which
no packets are sampled) after the current "samplingTimeInterval"
is over.

For example, this Information Element may used to describe the
configuration of a systematic time-based Sampling Selector.

Abstract Data Type: unsigned32

Data Type Semantics: quantity

ElementId: 308

Status: current

Units: microseconds

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8.2.6. samplingSize

Description:

This Information Element specifies the number of elements taken
from the parent Population for random Sampling methods.

For example, this Information Element may be used to describe the
configuration of a random n-out-of-N Sampling Selector.

Abstract Data Type: unsigned32

Data Type Semantics: quantity

ElementId: 309

Status: current

Units: packets

8.2.7. samplingPopulation

Description:

This Information Element specifies the number of elements in the
parent Population for random Sampling methods.

For example, this Information Element may be used to describe the
configuration of a random n-out-of-N Sampling Selector.

Abstract Data Type: unsigned32

Data Type Semantics: quantity

ElementId: 310

Status: current

Units: packets

8.2.8. samplingProbability

Description:

This Information Element specifies the probability that a packet
is sampled, expressed as a value between 0 and 1. The probability
is equal for every packet. A value of 0 means no packet was
sampled since the probability is 0.

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For example, this Information Element may be used to describe the
configuration of a uniform probabilistic Sampling Selector.

Abstract Data Type: float64

Data Type Semantics: quantity

ElementId: 311

Status: current

8.3. Hash Configuration (326-334)

The following Information Elements can be used for describing the
Sampling configuration of a Selection Process. The individual
parameters are explained in more detail in Sections 6.2, 3.8, and 7.1
of [RFC5475].

+-----+----------------------------+-----+----------------------------+
| ID | Name | ID | Name |
+-----+----------------------------+-----+----------------------------+
| 326 | digestHashValue | 331 | hashSelectedRangeMin |
| 327 | hashIPPayloadOffset | 332 | hashSelectedRangeMax |
| 328 | hashIPPayloadSize | 333 | hashDigestOutput |
| 329 | hashOutputRangeMin | 334 | hashInitialiserValue |
| 330 | hashOutputRangeMax | | |
+-----+----------------------------+-----+----------------------------+

8.3.1. digestHashValue

Description:

This Information Element specifies the value from the digest hash
function.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

Data Type Semantics: quantity

ElementId: 326

Status: current

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RFC 5477 PSAMP Information Model March 2009

8.3.2. hashIPPayloadOffset

Description:

This Information Element specifies the IP payload offset used by a
Hash-based Selection Selector.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

Data Type Semantics: quantity

ElementId: 327

Status: current

8.3.3. hashIPPayloadSize

Description:

This Information Element specifies the IP payload size used by a
Hash-based Selection Selector.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

Data Type Semantics: quantity

ElementId: 328

Status: current

8.3.4. hashOutputRangeMin

Description:

This Information Element specifies the value for the beginning of
a hash function's potential output range.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

Data Type Semantics: quantity

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ElementId: 329

Status: current

8.3.5. hashOutputRangeMax

Description:

This Information Element specifies the value for the end of a hash
function's potential output range.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

Data Type Semantics: quantity

ElementId: 330

Status: current

8.3.6. hashSelectedRangeMin

Description:

This Information Element specifies the value for the beginning of
a hash function's selected range.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

Data Type Semantics: quantity

ElementId: 331

Status: current

8.3.7. hashSelectedRangeMax

Description:

This Information Element specifies the value for the end of a hash
function's selected range.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

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RFC 5477 PSAMP Information Model March 2009

Data Type Semantics: quantity

ElementId: 332

Status: current

8.3.8. hashDigestOutput

Description:

This Information Element contains a boolean value that is TRUE if
the output from this hash Selector has been configured to be
included in the packet report as a packet digest, else FALSE.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: boolean

Data Type Semantics: quantity

ElementId: 333

Status: current

8.3.9. hashInitialiserValue

Description:

This Information Element specifies the initialiser value to the
hash function.

See also Sections 6.2, 3.8, and 7.1 of [RFC5475].

Abstract Data Type: unsigned64

Data Type Semantics: quantity

ElementId: 334

Status: current

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8.4. Timestamps (322-325)

The Information Elements listed below contain timestamps. They can
be used for reporting the observation time of a single packet.

+-----+----------------------------+-----+----------------------------+
| ID | Name | ID | Name |
+-----+----------------------------+-----+----------------------------+
| 322 | observationTimeSeconds | 324 | observationTimeMicroseconds|
| 323 | observationTimeMilliseconds| 325 | observationTimeNanoseconds |
+-----+----------------------------+-----+----------------------------+

8.4.1. observationTimeSeconds

Description:

This Information Element specifies the absolute time in seconds of
an observation.

Abstract Data Type: dateTimeSeconds

Data Type Semantics: quantity

ElementId: 322

Status: current

Units: seconds

8.4.2. observationTimeMilliseconds

Description:

This Information Element specifies the absolute time in
milliseconds of an observation.

Abstract Data Type: dateTimeMilliseconds

Data Type Semantics: quantity

ElementId: 323

Status: current

Units: milliseconds

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8.4.3. observationTimeMicroseconds

Description:

This Information Element specifies the absolute time in
microseconds of an observation.

Abstract Data Type: dateTimeMicroseconds

Data Type Semantics: quantity

ElementId: 324

Status: current

Units: microseconds

8.4.4. observationTimeNanoseconds

Description:

This Information Element specifies the absolute time in
nanoseconds of an observation.

Abstract Data Type: dateTimeNanoseconds

Data Type Semantics: quantity

ElementId: 325

Status: current

Units: nanoseconds

8.5. Packet Data (313-314, 316-317)

The following Information Elements are all used for reporting raw
content of a packet. All Information Elements containing sections of
the observed packet can also be used in IPFIX [RFC5101]. If the
values for those sections vary for different packets in a Flow, then
the Flow Report will contain the value observed in the first packet
of the Flow.

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RFC 5477 PSAMP Information Model March 2009

+-----+----------------------------+-----+----------------------------+
| ID | Name | ID | Name |
+-----+----------------------------+-----+----------------------------+
| 313 | ipHeaderPacketSection | 316 | mplsLabelStackSection |
| 314 | ipPayloadPacketSection | 317 | mplsPayloadPacketSection |
+-----+----------------------------+-----+----------------------------+

8.5.1. ipHeaderPacketSection

Description:

This Information Element, which may have a variable length,
carries a series of octets from the start of the IP header of a
sampled packet.

With sufficient length, this element also reports octets from the
IP payload, subject to [RFC2804]. See the Security Considerations
section.

The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.

Abstract Data Type: octetArray

ElementId: 313

Status: current

8.5.2. ipPayloadPacketSection

Description:

This Information Element, which may have a variable length,
carries a series of octets from the start of the IP payload of a
sampled packet.

The IPv4 payload is that part of the packet that follows the IPv4
header and any options, which [RFC0791] refers to as "data" or
"data octets". For example, see the examples in [RFC0791],
Appendix A.

The IPv6 payload is the rest of the packet following the 40-octet
IPv6 header. Note that any extension headers present are
considered part of the payload. See [RFC2460] for the IPv6
specification.

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The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.

Abstract Data Type: octetArray

ElementId: 314

Status: current

8.5.3. mplsLabelStackSection

Description:

This Information Element, which may have a variable length,
carries the first n octets from the MPLS label stack of a sampled
packet.

With sufficient length, this element also reports octets from the
MPLS payload, subject to [RFC2804]. See the Security
Considerations section.

See [RFC3031] for the specification of MPLS packets.

See [RFC3032] for the specification of the MPLS label stack.

The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.

Abstract Data Type: octetArray

ElementId: 316

Status: current

8.5.4. mplsPayloadPacketSection

Description:

This Information Element, which may have a variable length,
carries the first n octets from the MPLS payload of a sampled
packet, being data that follows immediately after the MPLS label
stack.

See [RFC3031] for the specification of MPLS packets.

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See [RFC3032] for the specification of the MPLS label stack.

The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.

Abstract Data Type: octetArray

ElementId: 317

Status: current

8.6. Statistics (318-321, 336-338)

Information Elements in this section can be used for reporting
statistics from the Metering Process.

+-----+----------------------------+-----+----------------------------+
| ID | Name | ID | Name |
+-----+----------------------------+-----+----------------------------+
| 318 | selectorIdTotalPktsObserved| 336 | upperCILimit |
| 319 | selectorIdTotalPktsSelected| 337 | lowerCILimit |
| 320 | absoluteError | 338 | confidenceLevel |
| 321 | relativeError | | |
+-----+----------------------------+-----+----------------------------+

8.6.1. selectorIdTotalPktsObserved

Description:

This Information Element specifies the total number of packets
observed by a Selector, for a specific value of SelectorId.

This Information Element should be used in an Options Template
scoped to the observation to which it refers. See Section 3.4.2.1
of the IPFIX protocol document [RFC5101].

Abstract Data Type: unsigned64

Data Type Semantics: totalCounter

ElementId: 318

Status: current

Units: packets

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8.6.2. selectorIdTotalPktsSelected

Description:

This Information Element specifies the total number of packets
selected by a Selector, for a specific value of SelectorId.

This Information Element should be used in an Options Template
scoped to the observation to which it refers. See Section 3.4.2.1
of the IPFIX protocol document [RFC5101].

Abstract Data Type: unsigned64

Data Type Semantics: totalCounter

ElementId: 319

Status: current

Units: packets

8.6.3. absoluteError

Description:

This Information Element specifies the maximum possible
measurement error of the reported value for a given Information
Element. The absoluteError has the same unit as the Information
Element with which it is associated. The real value of the metric
can differ by absoluteError (positive or negative) from the
measured value.

This Information Element provides only the error for measured
values. If an Information Element contains an estimated value
(from Sampling), the confidence boundaries and confidence level
have to be provided instead, using the upperCILimit, lowerCILimit,
and confidenceLevel Information Elements.

This Information Element should be used in an Options Template
scoped to the observation to which it refers. See section 3.4.2.1
of the IPFIX protocol document [RFC5101].

Abstract Data Type: float64

Data Type Semantics: quantity

ElementId: 320

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Status: current

Units: The units of the Information Element for which the error is
specified.

8.6.4. relativeError

Description:

This Information Element specifies the maximum possible positive
or negative error ratio for the reported value for a given
Information Element as a percentage of the measured value. The
real value of the metric can differ by relativeError percent
(positive or negative) from the measured value.

This Information Element provides only the error for measured
values. If an Information Element contains an estimated value
(from Sampling), the confidence boundaries and confidence level
have to be provided instead, using the upperCILimit, lowerCILimit,
and confidenceLevel Information Elements.

This Information Element should be used in an Options Template
scoped to the observation to which it refers. See Section 3.4.2.1
of the IPFIX protocol document [RFC5101].

Abstract Data Type: float64

Data Type Semantics: quantity

ElementId: 321

Status: current

8.6.5. upperCILimit

Description:

This Information Element specifies the upper limit of a confidence
interval. It is used to provide an accuracy statement for an
estimated value. The confidence limits define the range in which
the real value is assumed to be with a certain probability p.
Confidence limits always need to be associated with a confidence
level that defines this probability p. Please note that a
confidence interval only provides a probability that the real
value lies within the limits. That means the real value can lie
outside the confidence limits.

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The upperCILimit, lowerCILimit, and confidenceLevel Information
Elements should all be used in an Options Template scoped to the
observation to which they refer. See Section 3.4.2.1 of the IPFIX
protocol document [RFC5101].

Note that the upperCILimit, lowerCILimit, and confidenceLevel are
all required to specify confidence, and should be disregarded
unless all three are specified together.

Abstract Data Type: float64

Data Type Semantics: quantity

ElementId: 336

Status: current

8.6.6. lowerCILimit

Description:

This Information Element specifies the lower limit of a confidence
interval. For further information, see the description of
upperCILimit.

The upperCILimit, lowerCILimit, and confidenceLevel Information
Elements should all be used in an Options Template scoped to the
observation to which they refer. See Section 3.4.2.1 of the IPFIX
protocol document [RFC5101].

Note that the upperCILimit, lowerCILimit, and confidenceLevel are
all required to specify confidence, and should be disregarded
unless all three are specified together.

Abstract Data Type: float64

Data Type Semantics: quantity

ElementId: 337

Status: current

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8.6.7. confidenceLevel

Description:

This Information Element specifies the confidence level. It is
used to provide an accuracy statement for estimated values. The
confidence level provides the probability p with which the real
value lies within a given range. A confidence level always needs
to be associated with confidence limits that define the range in
which the real value is assumed to be.

The upperCILimit, lowerCILimit, and confidenceLevel Information
Elements should all be used in an Options Template scoped to the
observation to which they refer. See Section 3.4.2.1 of the IPFIX
protocol document [RFC5101].

Note that the upperCILimit, lowerCILimit, and confidenceLevel are
all required to specify confidence, and should be disregarded
unless all three are specified together.

Abstract Data Type: float64

Data Type Semantics: quantity

ElementId: 338

Status: current

9. Security Considerations

The PSAMP information model itself does not directly introduce
security issues. Rather, it defines a set of attributes that may for
privacy or business issues be considered sensitive information.

For example, exporting values of header fields may make attacks
possible for the receiver of this information, which would otherwise
only be possible for direct observers of the reported Flows along the
data path. Specifically, the Information Elements pertaining to
packet sections MUST target no more than the packet header, some
subsequent bytes of the packet, and encapsulating headers if present.
Full packet capture of arbitrary packet streams is explicitly out of
scope, per [RFC2804].

The underlying protocol used to exchange the information described
here MUST therefore apply appropriate procedures to guarantee the
integrity and confidentiality of the exported information. Such
procedures are defined in separate documents, specifically the IPFIX
protocol document [RFC5101].

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RFC 5477 PSAMP Information Model March 2009

10. IANA Considerations

The PSAMP information model, as set out in this document, has two
sets of assigned numbers. Considerations for assigning them are
discussed in this section, using the example policies as set out in
the "Guidelines for IANA Considerations" document [RFC5226].

10.1. Related Considerations

As the PSAMP protocol uses the IPFIX protocol, refer to the IANA
Considerations section in [RFC5102] for the assignments of numbers
used in the protocol and for the numbers used in the information
model.

10.2. PSAMP-Related Considerations

This document specifies an initial set of PSAMP Information Elements
fulfilling the needs specified in [RFC5475], as an extension to the
IPFIX Information Elements [RFC5102].

Note that the PSAMP Information Element IDs were initially started at
value 301, in order to leave a gap for any ongoing IPFIX work
requiring new Information Elements. It is expected that this gap in
the Information Element numbering will be filled in by IANA with new
IPFIX Information Elements.

Each new selection method MUST be assigned a unique value in the
selectorAlgorithm registry. Its configuration parameter(s), along
with the way to report them with an Options Template, MUST be clearly
specified. The initial content of the selectorAlgorithm registry is
found in Section 8.2.1.

New assignments for the PSAMP selection method will be administered
by IANA and are subject to Expert Review [RFC5226]. The group of
experts must double check the Information Elements definitions with
already defined Information Elements for completeness, accuracy, and
redundancy. Those experts will initially be drawn from the Working
Group Chairs and document editors of the IPFIX and PSAMP Working
Groups. The selectorAlgorithm registry is maintained by IANA and can
be updated as long as specifications of the new method(s) and any new
Information Elements are provided.

11. References

11.1. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

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RFC 5477 PSAMP Information Model March 2009

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.

[RFC5101] Claise, B., "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", RFC 5101, January 2008.

[RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J.
Meyer, "Information Model for IP Flow Information Export",
RFC 5102, January 2008.

[RFC5475] Zseby, T., Molina, M., Duffield, D., Niccolini, S., and F.
Rapall, "Sampling and Filtering Techniques for IP Packet
Selection", RFC 5475, March 2009.

[RFC5476] Claise, B., Ed., "Packet Sampling (PSAMP) Protocol
Specifications", RFC 5476, March 2009.

11.2. Informative References

[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
September 1981.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.

[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.

[RFC2804] IAB and IESG, "IETF Policy on Wiretapping", RFC 2804,
May 2000.

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

[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001.

[RFC5474] Duffield, N., Ed., "A Framework for Packet Selection and
Reporting", RFC 5474, March 2009.

Dietz, et al. Standards Track [Page 28]

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Appendix A. Formal Specification of PSAMP Information Elements

This appendix contains a formal description of the PSAMP information
model XML document. Note that this appendix is of informational
nature, while the text in Section 8 generated from this appendix is
normative.

Using a formal and machine-readable syntax for the information model
enables the creation of PSAMP-aware tools that can automatically
adapt to extensions to the information model, by simply reading
updated information model specifications.

The wide availability of XML-aware tools and libraries for client
devices is a primary consideration for this choice. In particular,
libraries for parsing XML documents are readily available. Also,
mechanisms such as the Extensible Stylesheet Language (XSL) allow for
transforming a source XML document into other documents. This draft
was authored in XML and transformed according to [RFC2629].

It should be noted that the use of XML in Exporters, Collectors, or
other tools is not mandatory for the deployment of PSAMP. In
particular, exporting processes do not produce or consume XML as part
of their operation. It is expected that PSAMP Collectors MAY take
advantage of the machine readability of the information model vs.
hardcoding their behavior or inventing proprietary means for
accommodating extensions.

<?xml version="1.0" encoding="UTF-8"?>

<fieldDefinitions xmlns="urn:ietf:params:xml:ns:ipfix-info"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:params:xml:ns:ipfix-info
ipfix-info.xsd">
<field name="selectionSequenceId" dataType="unsigned64"
dataTypeSemantics="identifier" elementId="301" status="current"
group="identifiers">
<description>
<paragraph>
From all the packets observed at an Observation Point, a subset
of the packets is selected by a sequence of one or more
Selectors. The selectionSequenceId is a unique value per
Observation Domain, specifying the Observation Point and the

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sequence of Selectors through which the packets are selected.
</paragraph>
</description>
</field>

<field name="selectorId" dataType="unsigned16"
dataTypeSemantics="identifier" elementId="302" status="current"
group="identifiers">
<description>
<paragraph>
The Selector ID is the unique ID identifying a Primitive
Selector. Each Primitive Selector must have a unique ID in the
Observation Domain.
</paragraph>
</description>
</field>

<field name="informationElementId" dataType="unsigned16"
dataTypeSemantics="identifier" elementId="303" status="current"
group="identifiers">
<description>
<paragraph>
This Information Element contains the ID of another Information
Element.
</paragraph>
</description>
</field>

<field name="selectorAlgorithm" dataType="unsigned16"
dataTypeSemantics="identifier" elementId="304" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element identifies the packet selection
methods (e.g., Filtering, Sampling) that are applied by
the Selection Process.

Most of these methods have parameters. Further
Information Elements are needed to fully specify packet
selection with these methods and all their parameters.

The methods listed below are defined in
[RFC5475]. For their parameters,
Information Elements are defined in the information model
document. The names of these Information Elements are
listed for each method identifier.

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Further method identifiers may be added to the list
below. It might be necessary to define new Information
Elements to specify their parameters.

The selectorAlgorithm registry is maintained by IANA. New
assignments for the registry will be administered by IANA
and are subject to Expert Review [RFC5226].

The registry can be updated when specifications of the new
method(s) and any new Information Elements are provided.

The group of experts must double check the selectorAlgorithm
definitions and Information Elements with already defined
selectorAlgorithms and Information Elements for completeness,
accuracy, and redundancy. Those experts will initially be drawn
from the Working Group Chairs and document editors of the IPFIX
and PSAMP Working Groups.

The following packet selection methods identifiers are
defined here:

+----+------------------------+------------------------+
| ID | Method | Parameters |
+----+------------------------+------------------------+
| 1 | Systematic count-based | samplingPacketInterval |
| | Sampling | samplingPacketSpace |
+----+------------------------+------------------------+
| 2 | Systematic time-based | samplingTimeInterval |
| | Sampling | samplingTimeSpace |
+----+------------------------+------------------------+
| 3 | Random n-out-of-N | samplingSize |
| | Sampling | samplingPopulation |
+----+------------------------+------------------------+
| 4 | Uniform probabilistic | samplingProbability |
| | Sampling | |
+----+------------------------+------------------------+
| 5 | Property Match | no agreed parameters |
| | Filtering | |
+----+------------------------+------------------------+
| Hash-based Filtering | hashInitialiserValue |
+----+------------------------+ hashIPPayloadOffset |
| 6 | using BOB | hashIPPayloadSize |
+----+------------------------+ hashSelectedRangeMin |
| 7 | using IPSX | hashSelectedRangeMax |
+----+------------------------+ hashOutputRangeMin |
| 8 | using CRC | hashOutputRangeMax |
+----+------------------------+------------------------+

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There is a broad variety of possible parameters that could be
used for Property Match Filtering (5), but currently there are
no agreed parameters specified.
</paragraph>
</description>
</field>

<field name="samplingPacketInterval" dataType="unsigned32"
dataTypeSemantics="quantity" elementId="305" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element specifies the number of packets that
are consecutively sampled. A value of 100 means that
100 consecutive packets are sampled.

For example, this Information Element may be used to describe
the configuration of a systematic count-based Sampling Selector.
</paragraph>
</description>
<units>packets</units>
</field>

<field name="samplingPacketSpace" dataType="unsigned32"
dataTypeSemantics="quantity" elementId="306" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element specifies the number of packets between
two "samplingPacketInterval"s. A value of 100 means that the
next interval starts 100 packets (which are not sampled)
after the current "samplingPacketInterval" is over.

For example, this Information Element may be used to describe
the configuration of a systematic count-based Sampling Selector.
</paragraph>
</description>
<units>packets</units>
</field>

<field name="samplingTimeInterval" dataType="unsigned32"
dataTypeSemantics="quantity" elementId="307" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element specifies the time interval in
microseconds during which all arriving packets are sampled.

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For example, this Information Element may be used to describe
the configuration of a systematic time-based Sampling Selector.
</paragraph>
</description>
<units>microseconds</units>
</field>

<field name="samplingTimeSpace" dataType="unsigned32"
dataTypeSemantics="quantity" elementId="308" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element specifies the time interval in
microseconds between two "samplingTimeInterval"s. A value of 100
means that the next interval starts 100 microseconds
(during which no packets are sampled) after the current
"samplingTimeInterval" is over.

For example, this Information Element may used to describe the
configuration of a systematic time-based Sampling Selector.
</paragraph>
</description>
<units>microseconds</units>
</field>

<field name="samplingSize" dataType="unsigned32"
dataTypeSemantics="quantity" elementId="309" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element specifies the number of elements taken
from the parent Population for random Sampling methods.

For example, this Information Element may be used to describe
the configuration of a random n-out-of-N Sampling Selector.
</paragraph>
</description>
<units>packets</units>
</field>

<field name="samplingPopulation" dataType="unsigned32"
dataTypeSemantics="quantity" elementId="310" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element specifies the number of elements in the
parent Population for random Sampling methods.

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For example, this Information Element may be used to describe
the configuration of a random n-out-of-N Sampling Selector.
</paragraph>
</description>
<units>packets</units>
</field>

<field name="samplingProbability" dataType="float64"
dataTypeSemantics="quantity" elementId="311" status="current"
group="sampling configuration">
<description>
<paragraph>
This Information Element specifies the probability that a packet
is sampled, expressed as a value between 0 and 1. The
probability is equal for every packet. A value of 0 means no
packet was sampled since the probability is 0.

For example, this Information Element may be used to describe
the configuration of a uniform probabilistic Sampling Selector.
</paragraph>
</description>
</field>

<field name="ipHeaderPacketSection" dataType="octetArray"
elementId="313" status="current" group="packet data">
<description>
<paragraph>
This Information Element, which may have a variable length,
carries a series of octets from the start of the IP header of a
sampled packet.

With sufficient length, this element also reports octets from
the IP payload, subject to [RFC2804]. See the Security
Considerations section.

The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.
</paragraph>
</description>
</field>

<field name="ipPayloadPacketSection" dataType="octetArray"
elementId="314" status="current" group="packet data">
<description>
<paragraph>
This Information Element, which may have a variable length,

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carries a series of octets from the start of the IP payload of a
sampled packet.

The IPv4 payload is that part of the packet that follows the
IPv4 header and any options, which [RFC0791] refers to as "data"
or "data octets". For example, see the examples in [RFC0791],
Appendix A.

The IPv6 payload is the rest of the packet following the
40-octet IPv6 header. Note that any extension headers present
are considered part of the payload. See [RFC2460] for the IPv6
specification.

The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.
</paragraph>
</description>
</field>

<field name="mplsLabelStackSection" dataType="octetArray"
elementId="316" status="current" group="packet data">
<description>
<paragraph>
This Information Element, which may have a variable length,
carries the first n octets from the MPLS label stack of a
sampled packet.

With sufficient length, this element also reports octets from
the MPLS payload, subject to [RFC2804]. See the Security
Considerations section.

See [RFC3031] for the specification of MPLS packets.

See [RFC3032] for the specification of the MPLS label stack.

The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.
</paragraph>
</description>
</field>

<field name="mplsPayloadPacketSection" dataType="octetArray"
elementId="317" status="current" group="packet data">
<description>

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<paragraph>
This Information Element, which may have a variable length,
carries the first n octets from the MPLS payload of a sampled
packet, being data that follows immediately after the MPLS label
stack.

See [RFC3031] for the specification of MPLS packets.

See [RFC3032] for the specification of the MPLS label stack.

The size of the exported section may be constrained due to
limitations in the IPFIX protocol.

The data for this field MUST NOT be padded.
</paragraph>
</description>
</field>

<field name="selectorIdTotalPktsObserved" dataType="unsigned64"
dataTypeSemantics="totalCounter" elementId="318" status="current"
group="statistics">
<description>
<paragraph>
This Information Element specifies the total number of packets
observed by a Selector, for a specific value of SelectorId.

This Information Element should be used in an Options Template
scoped to the observation to which it refers.
See Section 3.4.2.1 of the IPFIX protocol document [RFC5101].
</paragraph>
</description>
<units>packets</units>
</field>

<field name="selectorIdTotalPktsSelected" dataType="unsigned64"
dataTypeSemantics="totalCounter" elementId="319" status="current"
group="statistics">
<description>
<paragraph>
This Information Element specifies the total number of packets
selected by a Selector, for a specific value of SelectorId.

This Information Element should be used in an Options Template
scoped to the observation to which it refers.
See Section 3.4.2.1 of the IPFIX protocol document [RFC5101].
</paragraph>
</description>
<units>packets</units>

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</field>

<field name="absoluteError" dataType="float64"
dataTypeSemantics="quantity" elementId="320" status="current"
group="statistics">
<description>
<paragraph>
This Information Element specifies the maximum possible
measurement error of the reported value for a given Information
Element. The absoluteError has the same unit as the Information
Element with which it is associated. The real value of the
metric can differ by absoluteError (positive or negative) from
the measured value.

This Information Element provides only the
error for measured values. If an Information Element contains
an estimated value (from Sampling), the confidence boundaries
and confidence level have to be provided instead, using the
upperCILimit, lowerCILimit, and confidenceLevel Information
Elements.

This Information Element should be used in an Options Template
scoped to the observation to which it refers.
See Section 3.4.2.1 of the IPFIX protocol document [RFC5101].
</paragraph>
</description>
<units>
The units of the Information Element for which the error is
specified.
</units>
</field>

<field name="relativeError" dataType="float64"
dataTypeSemantics="quantity" elementId="321" status="current"
group="statistics">
<description>
<paragraph>
This Information Element specifies the maximum possible positive
or negative error ratio for the reported value for a given
Information Element as a percentage of the measured value.
The real value of the metric can differ by relativeError percent
(positive or negative) from the measured value.

This Information Element provides only the error for measured
values. If an Information Element contains an estimated value
(from Sampling), the confidence boundaries and confidence
level have to be provided instead, using the upperCILimit,
lowerCILimit, and confidenceLevel Information Elements.

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RFC 5477 PSAMP Information Model March 2009

This Information Element should be used in an Options Template
scoped to the observation to which it refers.
See Section 3.4.2.1 of the IPFIX protocol document [RFC5101].
</paragraph>
</description>
</field>

<field name="observationTimeSeconds" dataType="dateTimeSeconds"
dataTypeSemantics="quantity" elementId="322" status="current"
group="timestamps">
<description>
<paragraph>
This Information Element specifies the absolute time in seconds
of an observation.
</paragraph>
</description>
<units>seconds</units>
</field>

<field name="observationTimeMilliseconds"
dataType="dateTimeMilliseconds" dataTypeSemantics="quantity"
elementId="323" status="current" group="timestamps">
<description>
<paragraph>
This Information Element specifies the absolute time in
milliseconds of an observation.
</paragraph>
</description>
<units>milliseconds</units>
</field>

<field name="observationTimeMicroseconds"
dataType="dateTimeMicroseconds" dataTypeSemantics="quantity"
elementId="324" status="current" group="timestamps">
<description>
<paragraph>
This Information Element specifies the absolute time in
microseconds of an observation.
</paragraph>
</description>
<units>microseconds</units>
</field>

<field name="observationTimeNanoseconds"
dataType="dateTimeNanoseconds" dataTypeSemantics="quantity"
elementId="325" status="current" group="timestamps">
<description>
<paragraph>

Dietz, et al. Standards Track [Page 40]

RFC 5477 PSAMP Information Model March 2009

This Information Element specifies the absolute time in
nanoseconds of an observation.
</paragraph>
</description>
<units>nanoseconds</units>
</field>

<field name="digestHashValue" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="326" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the value from the digest
hash function.

See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="hashIPPayloadOffset" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="327" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the IP payload offset used by
a Hash-based Selection Selector.

See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="hashIPPayloadSize" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="328" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the IP payload size used by a
Hash-based Selection Selector.
See also Sections 6.2, 3.8, and 7.1 of
[RFC5475]
</paragraph>
</description>
</field>

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RFC 5477 PSAMP Information Model March 2009

<field name="hashOutputRangeMin" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="329" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the value for the beginning
of a hash function's potential output range.
See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="hashOutputRangeMax" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="330" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the value for the end of a
hash function's potential output range.

See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="hashSelectedRangeMin" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="331" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the value for the beginning
of a hash function's selected range.

See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="hashSelectedRangeMax" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="332" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the value for the end of a
hash function's selected range.

Dietz, et al. Standards Track [Page 42]

RFC 5477 PSAMP Information Model March 2009

See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="hashDigestOutput" dataType="boolean"
dataTypeSemantics="quantity" elementId="333" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element contains a boolean value that is TRUE
if the output from this hash Selector has been configured to be
included in the packet report as a packet digest, else FALSE.

See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="hashInitialiserValue" dataType="unsigned64"
dataTypeSemantics="quantity" elementId="334" status="current"
group="hash configuration">
<description>
<paragraph>
This Information Element specifies the initialiser value to the
hash function.

See also Sections 6.2, 3.8, and 7.1 of
[RFC5475].
</paragraph>
</description>
</field>

<field name="upperCILimit" dataType="float64"
dataTypeSemantics="quantity" elementId="336" status="current"
group="statistics">
<description>
<paragraph>
This Information Element specifies the upper limit of a
confidence interval. It is used to provide an accuracy
statement for an estimated value. The confidence limits
define the range in which the real value is assumed to be
with a certain probability p. Confidence limits always need
to be associated with a confidence level that defines this
probability p. Please note that a confidence interval only
provides a probability that the real value lies within the

Dietz, et al. Standards Track [Page 43]

RFC 5477 PSAMP Information Model March 2009

limits. That means the real value can lie outside the
confidence limits.

The upperCILimit, lowerCILimit, and confidenceLevel
Information Elements should all be used in an Options Template
scoped to the observation to which they refer.
See Section 3.4.2.1 of the IPFIX protocol document [RFC5101].

Note that the upperCILimit, lowerCILimit, and confidenceLevel
are all required to specify confidence, and should be
disregarded unless all three are specified together.
</paragraph>
</description>
</field>

<field name="lowerCILimit" dataType="float64"
dataTypeSemantics="quantity" elementId="337" status="current"
group="statistics">
<description>
<paragraph>
This Information Element specifies the lower limit of a
confidence interval. For further information, see the
description of upperCILimit.

The upperCILimit, lowerCILimit, and confidenceLevel
Information Elements should all be used in an Options Template
scoped to the observation to which they refer.
See Section 3.4.2.1 of the IPFIX protocol document [RFC5101].

Note that the upperCILimit, lowerCILimit, and confidenceLevel
are all required to specify confidence, and should be
disregarded unless all three are specified together.
</paragraph>
</description>
</field>

<field name="confidenceLevel" dataType="float64"
dataTypeSemantics="quantity" elementId="338" status="current"
group="statistics">
<description>
<paragraph>
This Information Element specifies the confidence level. It is
used to provide an accuracy statement for estimated values.
The confidence level provides the probability p with which the
real value lies within a given range. A confidence level
always needs to be associated with confidence limits that
define the range in which the real value is assumed to be.

Dietz, et al. Standards Track [Page 44]

RFC 5477 PSAMP Information Model March 2009

The upperCILimit, lowerCILimit, and confidenceLevel
Information Elements should all be used in an Options Template
scoped to the observation to which they refer.
See Section 3.4.2.1 of the IPFIX protocol document [RFC5101].

Note that the upperCILimit, lowerCILimit, and confidenceLevel
are all required to specify confidence, and should be
disregarded unless all three are specified together.
</paragraph>
</description>
</field>

</fieldDefinitions>

Authors' Addresses

Thomas Dietz
NEC Europe Ltd.
NEC Laboratories Europe
Network Research Division
Kurfuersten-Anlage 36
Heidelberg 69115
Germany

Phone: +49 6221 4342-128
EMail: [email protected]
URI: http://www.nw.neclab.eu

Benoit Claise
Cisco Systems, Inc.
De Kleetlaan 6a b1
Degem 1813
Belgium

Phone: +32 2 704 5622
EMail: [email protected]

Paul Aitken
Cisco Systems, Inc.
96 Commercial Quay
Edinburgh EH6 6LX
Scotland

Phone: +44 131 561 3616
EMail: [email protected]
URI: http://www.cisco.com/

Dietz, et al. Standards Track [Page 45]

RFC 5477 PSAMP Information Model March 2009

Falko Dressler
University of Erlangen-Nuremberg
Dept. of Computer Sciences
Martensstr. 3
Erlangen 91058
Germany

Phone: +49 9131 85-27914
EMail: [email protected]
URI: http://www7.informatik.uni-erlangen.de/~dressler

Georg Carle
Technical University of Munich
Institute for Informatics
Boltzmannstr. 3
Garching bei Muenchen 85737
Germany

Phone: +49 89 289-18030
EMail: [email protected]
URI: http://www.net.in.tum.de/~carle/

Dietz, et al. Standards Track [Page 46]