wdiff rfc7011.original rfc7011.txt

Network Working Group
Internet Engineering Task Force (IETF) B. Claise, Ed.
Internet Draft
Request for Comments: 7011 Cisco Systems, Inc.
Obsoletes: 5101
STD: 77 B. Trammell, Ed.
Obsoletes: 5101 ETH Zurich
Category: Standards Track ETH Zurich
Expires: January 12, 2014 July 11, P. Aitken
ISSN: 2070-1721 Cisco Systems, Inc.
September 2013

Specification of the IP Flow Information eXport Export (IPFIX) Protocol
for the Exchange of Flow Information
draft-ietf-ipfix-protocol-rfc5101bis-10

Abstract

This document specifies the IP Flow Information Export (IPFIX)
protocol that
protocol, which serves as a means for transmitting Traffic Flow
information over the network. In order to transmit Traffic Flow
information from an Exporting Process to a Collecting Process, a
common representation of flow data and a standard means of
communicating them is are required. This document describes how the
IPFIX Data and Template Records are carried over a number of
transport protocols from an IPFIX Exporting Process to an IPFIX
Collecting Process. This document obsoletes RFC 5101.

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of six months this document, any errata,
and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on August 22, 2013.
http://www.rfc-editor.org/info/rfc7011.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 ....................................................5
1.1. Changes since RFC 5101 . . . . . . . . . . . . . . . . . . 5 .....................................5
1.2. IPFIX Documents Overview . . . . . . . . . . . . . . . . . 7 ...................................6
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 8 .....................................................7
2.1. Terminology Summary Table . . . . . . . . . . . . . . . . 13 .................................13
3. IPFIX Message Format . . . . . . . . . . . . . . . . . . . . . 13 ...........................................13
3.1. Message Header Format . . . . . . . . . . . . . . . . . . 15 .....................................15
3.2. Field Specifier Format . . . . . . . . . . . . . . . . . . 16 ....................................16
3.3. Set and Set Header Format . . . . . . . . . . . . . . . . 17 .................................18
3.3.1. Set Format . . . . . . . . . . . . . . . . . . . . . . 18 .........................................18
3.3.2. Set Header Format . . . . . . . . . . . . . . . . . . 19 ..................................19
3.4. Record Format . . . . . . . . . . . . . . . . . . . . . . 19 .............................................20
3.4.1. Template Record Format . . . . . . . . . . . . . . . . 19 .............................20
3.4.2. Options Template Record Format . . . . . . . . . . . . 22 .....................23
3.4.2.1. Scope . . . . . . . . . . . . . . . . . . . . . . 22 .....................................23
3.4.2.2. Options Template Record Format . . . . . . . . . . 22 ............24
3.4.3. Data Record Format . . . . . . . . . . . . . . . . . . 25 .................................27
4. Specific Reporting Requirements . . . . . . . . . . . . . . . 26 ................................28
4.1. The Metering Process Statistics Options Template . . . . . 26 ..........29
4.2. The Metering Process Reliability Statistics
Options Template . . . . . . . . . . . . . . . . . . . . . . . . . 27 ..........................................29
4.3. The Exporting Process Reliability Statistics
Options Template . . . . . . . . . . . . . . . . . . . . . . . . . 28 ..........................................31
4.4. The Flow Keys Options Template . . . . . . . . . . . . . . 30 ............................32
5. Timing Considerations . . . . . . . . . . . . . . . . . . . . 30
5.1 ..........................................32
5.1. IPFIX Message Header Export Time and Flow Record Time . . . 30
5.2 .....32
5.2. Supporting Timestamp Wraparound . . . . . . . . . . . . . . 31 ...........................33
6. Linkage with the Information Model . . . . . . . . . . . . . . 31 .............................34
6.1. Encoding of IPFIX Data Types . . . . . . . . . . . . . . . 32 ..............................34
6.1.1. Integral Data Types . . . . . . . . . . . . . . . . . . 32 ................................34
6.1.2. Address Types . . . . . . . . . . . . . . . . . . . . . 32 ......................................34
6.1.3. float32 . . . . . . . . . . . . . . . . . . . . . . . . 32 ............................................34
6.1.4. float64 . . . . . . . . . . . . . . . . . . . . . . . . 32 ............................................34
6.1.5. boolean . . . . . . . . . . . . . . . . . . . . . . . . 32 ............................................35
6.1.6. string and octetArray . . . . . . . . . . . . . . . . . 32 ..............................35
6.1.7. dateTimeSeconds . . . . . . . . . . . . . . . . . . . . 33 ....................................35
6.1.8. dateTimeMilliseconds . . . . . . . . . . . . . . . . . 33
6.1.9 ...............................35
6.1.9. dateTimeMicroseconds . . . . . . . . . . . . . . . . . 33
6.1.10 ...............................35
6.1.10. dateTimeNanoseconds . . . . . . . . . . . . . . . . . . 34 ...............................36
6.2. Reduced Size Reduced-Size Encoding . . . . . . . . . . . . . . . . . . 34 .....................................36
7. Variable-Length Information Element . . . . . . . . . . . . . 35 ............................37
8. Template Management . . . . . . . . . . . . . . . . . . . . . 36 ............................................38
8.1. Template Withdrawal and Redefinition . . . . . . . . . . . 38
8.2 ......................40
8.2. Sequencing Template Management Actions . . . . . . . . . . 40 ....................42
8.3. Additional considerations Considerations for Template Management
over SCTP . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 .................................................43
8.4. Additional considerations Considerations for Template Management
over UDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 ..................................................44
9. The Collecting Process's Side . . . . . . . . . . . . . . . . . 42 ..................................45
9.1. Collecting Process handling Handling of malformed Malformed IPFIX Messages . . 43 ...46
9.2. Additional considerations Considerations for SCTP Collecting Processes . 44 ...46
9.3. Additional considerations Considerations for UDP Collecting Processes . . 44 ....46
10. Transport Protocol . . . . . . . . . . . . . . . . . . . . . 44 ............................................47
10.1. Transport Compliance and Transport Usage . . . . . . . . 45 .................47
10.2. SCTP . . . . . . . . . . . . . . . . . . . . . . . . . . 46 .....................................................48
10.2.1. Congestion Avoidance . . . . . . . . . . . . . . . . 46 ..............................48
10.2.2. Reliability . . . . . . . . . . . . . . . . . . . . . 46 .......................................49
10.2.3. MTU . . . . . . . . . . . . . . . . . . . . . . . . . 46 ...............................................49
10.2.4. Association Establishment and Shutdown . . . . . . . 46 ............49
10.2.5. Failover . . . . . . . . . . . . . . . . . . . . . . 47 ..........................................50
10.2.6. Streams . . . . . . . . . . . . . . . . . . . . . . . 47 ...........................................50
10.3. UDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 ......................................................50
10.3.1. Congestion Avoidance . . . . . . . . . . . . . . . . 48 ..............................50
10.3.2. Reliability . . . . . . . . . . . . . . . . . . . . . 48 .......................................51
10.3.3. MTU . . . . . . . . . . . . . . . . . . . . . . . . . 48 ...............................................51
10.3.4. Session Establishment and Shutdown . . . . . . . . . 49 ................51
10.3.5. Failover and Session Duplication . . . . . . . . . . 49 ..................51
10.4. TCP . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 ......................................................52
10.4.1. Congestion Avoidance . . . . . . . . . . . . . . . . 49
10.4.2. Reliability . . . . . . . . . . . . . . . . . . . . . 50
10.4.3. MTU . . . . . . . . . . . . . . . . . . . . . . . . . 50
10.4.4. Connection Establishment and Shutdown . . . . . . . . 50
10.4.5. Failover . . . . . . . . . . . . . . . . . . . . . . 51 Congestion Avoidance ..............................52
10.4.2. Reliability .......................................52
10.4.3. MTU ...............................................52
10.4.4. Connection Establishment and Shutdown .............53
10.4.5. Failover ..........................................53
11. Security Considerations . . . . . . . . . . . . . . . . . . . 51 .......................................54
11.1. Applicability of TLS and DTLS . . . . . . . . . . . . . . 52 ............................55
11.2. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 53 ....................................................56
11.3. Mutual Authentication . . . . . . . . . . . . . . . . . . 53 ....................................56
11.4. Protection against DoS Attacks . . . . . . . . . . . . . 54 ...........................57
11.5. When DTLS or TLS Is Not an Option . . . . . . . . . . . . 55 ........................58
11.6. Logging an IPFIX Attack . . . . . . . . . . . . . . . . . 56 ..................................58
11.7. Securing the Collector . . . . . . . . . . . . . . . . . 56 ...................................59
11.8. Privacy Considerations for Collected Data . . . . . . . . 56 ................59
12. Management Considerations . . . . . . . . . . . . . . . . . . 57 .....................................60
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 59 ...........................................61
Appendix A. IPFIX Encoding Examples . . . . . . . . . . . . . . . 60
A.1. Message Header Example . . . . . . . . . . . . . . . . . . 60
A.2. Template Set Examples . . . . . . . . . . . . . . . . . . 61 Examples ...............................62
A.1. Message Header Example ....................................62
A.2. Template Set Examples .....................................63
A.2.1. Template Set Using IANA Information Elements . . . . . 61 ..........63
A.2.2. Template Set Using Enterprise-Specific Information
Elements . . . . . . . . . . . . . . . . . . . . . . . 61 ..............................................64
A.3. Data Set Example . . . . . . . . . . . . . . . . . . . . . 63 ..........................................65
A.4. Options Template Set Examples . . . . . . . . . . . . . . 64 .............................66
A.4.1. Options Template Set Using IANA Information Elements . 64 ..66
A.4.2. Options Template Set Using Enterprise-Specific
Information . . . . . . . . . . . . . . . . . . . . . 64 Elements ..................................66
A.4.3. Options Template Set Using an Enterprise-Specific
Scope . . . . . . . . . . . . . . . . . . . . . . . . 65 .................................................67
A.4.4. Data Set Using an Enterprise-Specific Scope . . . . . 66 ...........68
A.5. Variable-Length Information Element Examples . . . . . . . 67 ..............69
A.5.1. Example of Variable-Length Information Element with
Length . . . . . . . . . . . . . . . . . . . . . . . . 67 Less Than 255 Octets ...........................69
A.5.2. Example of Variable-Length Information Element with
3 Octet Length Encoding . . . . . . . . . . . . . . . 67
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Normative References . . . . . . . . . . . . . . . . . . . . . . . 68
Informative References . . . . . . . . . . . . . . . . . . . . . . 69
3-Octet Length Encoding ...............................70
Normative References ..............................................71
Informative References ............................................71
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 72
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 72
Contributors' Addresses . . . . . . . . . . . . . . . . . . . . . 73 ...................................................74
Contributors ......................................................75

1. Introduction

Traffic on a data network can be seen as consisting of flows passing
through network elements. It For administrative or other purposes, it
is often interesting, useful, or even necessary to have access to
information about these flows that pass through the network elements for administrative or other purposes. elements.
A Collecting Process should be able to receive the flow Flow information
passing through multiple network elements within the data network.
This requires uniformity in the method of representing the flow
information and the means of communicating the flows from the network
elements to the collection point. This document specifies a protocol
to achieve these requirements. This document specifies in detail the
representation of different flows, as well as the additional data
required for flow interpretation, packet format, transport mechanisms
used, security concerns, etc.

1.1. Changes since RFC 5101

This document obsoletes the Proposed Standard revision of the IPFIX
Protocol Specification [RFC5101]. The protocol specified by this
document is interoperable with the protocol as specified in
[RFC5101]. The following changes have been made to this document
with respect to the previous document:

- All outstanding technical and editorial errata on [RFC5101] have
been addressed.

- As [IPFIX-IANA] the [IANA-IPFIX] registry is now the normative reference for all
Information Element definitions (see [RFC5102bis]), [RFC7012]), all definitions of
Information Elements in Section 4 have been replaced with
references to the that registry.

- The encoding of the dateTimeSeconds, dateTimeMilliseconds,
dateTimeMicroseconds, and dateTimeNanoseconds data types, and the
related encoding of the IPFIX Message Header Export Time field,
have been clarified, especially with respect to the epoch upon
which the timestamp data types are based.

- A new Section 5.2 has been added to address wraparound of these
timestamp data types after they overflow in 2032 - 2038 CE
(common era). the years 2032-2038.

- Clarifications on encoding, especially in Section 6: 6, have been
made: all IPFIX values are encoded in network byte order.

- Template management management, as described in section 8 Section 8, has been simplified
and clarified: the specification has been relaxed with respect to
[RFC5101], especially concerning potential failures in Template ID
reuse. Additional corner cases in template management have been
addressed. The new template management language is interoperable
with that in [RFC5101] to the extent that the behavior was defined
in the prior specification.

- Section 11.3 (Mutual Authentication) has been improved to refer to
current practices in TLS Transport Layer Security (TLS) mutual
authentication; references to Punycode were removed removed, as these are
covered in [RFC6125].

- Editorial improvements, including structural changes to sections Sections 8,
9, and 10 to improve readability. readability, have been applied. Behavior
common to all transport protocols has been separated out, with
exceptions per transport specifically noted. All template
management language (on both Exporting and Collecting Processes)
has been unified in
section Section 8.

- A new section Section 12 has been added on management considerations has been added.

1.2. IPFIX Documents Overview

The IPFIX protocol provides network administrators with access to IP
flow
Flow information. The architecture for the export of measured IP
flow
Flow information out of an IPFIX Exporting Process to a Collecting
Process is defined in [RFC5470], per the requirements defined in
[RFC3917]. This document specifies how IPFIX Data Records and
Templates are carried via a number of transport protocols from IPFIX
Exporting Processes to IPFIX Collecting Processes.

Four IPFIX optimizations/extensions are currently specified: a
bandwidth saving
bandwidth-saving method for the IPFIX protocol in [RFC5473], an
efficient method for exporting bidirectional flows in [RFC5103], a
method for the definition and export of complex data structures in
[RFC6313], and the specification of the Protocol for on IPFIX Mediations Mediators
[IPFIX-MED-PROTO] based on the IPFIX Mediation Framework [RFC6183].

A "file-based transport" for IPFIX, which defines how IPFIX Messages
can be stored in files for document-based workflows and for archival
purposes, is given discussed in [RFC5655].

IPFIX has a formal description of IPFIX Information Elements, Elements -- their
name, type
names, data types, and additional semantic information, information -- as
specified in
[RFC5102bis]. [RFC7012]. The registry is maintained by IANA [IPFIX-IANA].
[IANA-IPFIX]. The inline export of the Information Element type
information is specified in [RFC5610].

The framework for packet selection and reporting [RFC5474] enables
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. The set of packet selection techniques
(Sampling, Filtering, and hashing) standardized by PSAMP the Packet
Sampling (PSAMP) protocol is described in [ RFC5475]. [RFC5475]. The PSAMP
protocol [RFC5476], which uses IPFIX as its export protocol,
specifies the export of packet information from a PSAMP Exporting
Process to a PSAMP Collector. Instead of exporting PSAMP Packet
Reports, the stream of selected packets may also serve as input to
the generation of IPFIX Flow Records. Like IPFIX, PSAMP has a formal
description of its Information Elements, Elements: their name,
type, names, types, and
additional semantic information. The PSAMP information model is
defined in [RFC5477].

[RFC6615] specifies a MIB module for monitoring, and [RFC6728]
specifies a data model for configuring and monitoring IPFIX and PSAMP
compliant
PSAMP-compliant devices using the NETCONF protocol. Network Configuration Protocol
(NETCONF). [RFC6727] specifies the PSAMP MIB module as an extension
of the IPFIX SELECTOR MIB module defined in [RFC6615].

In terms of development, [RFC5153] provides guidelines for the
implementation and use of the IPFIX protocol, while [RFC5471]
provides guidelines for testing. Finally, [RFC5472] describes what
type
types of applications can use the IPFIX protocol and how they can use
the information provided. It furthermore shows how the IPFIX
framework relates to other architectures and frameworks.

2. Terminology

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

The definitions of the basic terms like Traffic Flow, Exporting
Process, Collecting Process, Observation Points, etc. are
semantically identical to those found in the IPFIX requirements
document [RFC3917]. Some of the terms have been expanded for more
clarity when defining the protocol. Additional terms required for
the protocol have also been defined. Definitions in this document
and in [RFC5470] are equivalent; definitions that are only relevant
to the IPFIX protocol only appear here.

The terminology summary table in Section 2.1 gives a quick overview
of the relationships among some of the different terms defined.

Observation Point

An Observation Point is a location in the network where packets
can be observed. Examples include: include a line to which a probe is
attached,
attached; a shared medium, such as an Ethernet-based LAN, LAN; a single
port of a router, router; or a set of interfaces (physical or logical) of
a router.

Note that every Observation Point is associated with an
Observation Domain (defined below), below) and that one Observation Point
may be a superset of several other Observation Points. For
example, one Observation Point can be an entire line card. That
would be the superset of the individual Observation Points at the
line card's interfaces.

Observation Domain

An Observation Domain is the largest set of Observation Points for
which Flow information can be aggregated by a Metering Process.
For example, a router line card may be an Observation Domain if it
is composed of several interfaces, each of which is an Observation
Point. In the IPFIX Message it generates, the Observation Domain
includes its Observation Domain ID, which is unique per Exporting
Process. That way, the Collecting Process can identify the
specific Observation Domain from the Exporter that sends the IPFIX
Messages. Every Observation Point is associated with an
Observation Domain. It is RECOMMENDED that Observation Domain IDs
also be unique per IPFIX Device.

Packet Treatment

Action(s)

"Packet Treatment" refers to action(s) performed on a packet by a
forwarding device or other middlebox, including forwarding,
dropping, delaying for traffic
shaping traffic-shaping purposes, etc.

Traffic Flow or Flow

There are several definitions of the term 'flow' being used by the
Internet community. Within the context of IPFIX IPFIX, we use the
following definition:

A Flow is defined as a set of packets or frames passing an
Observation Point in the network during a certain time interval.
All packets belonging to a particular Flow have a set of common
properties. Each property is defined as the result of applying a
function to the values of:

1. one or more packet header fields (e.g., destination IP
address), transport header fields (e.g., destination port
number), or application header fields (e.g., RTP header fields
[RFC3550]).

2. one or more characteristics of the packet itself (e.g., number
of MPLS labels, etc...). etc.).

3. one or more of the fields derived from Packet Treatment (e.g.,
next hop
next-hop IP address, the output interface, etc...). etc.).

A packet is defined as belonging to a Flow if it completely
satisfies all the defined properties of the Flow.

Note that the set of packets represented by a Flow may be empty;
that is, a Flow may represent zero or more packets. As sampling
is a Packet Treatment, this definition includes packets selected
by a sampling mechanism.

Flow Key

Each of the fields that:

1. belong to the packet header (e.g., destination IP address), or

2. are a property of the packet itself (e.g., packet length), or

3. are derived from Packet Treatment (e.g., Autonomous System (AS)
number),

and that are used to define a Flow (i.e., are the properties
common to all packets in the Flow) are termed Flow Keys. As an
example, the traditional '5-tuple' Flow Key of source and
destination IP address, source and destination transport port, and
transport protocol, groups together all packets belonging to a
single direction of communication on a single socket.

Flow Record

A Flow Record contains information about a specific Flow that was
observed at an Observation Point. A Flow Record contains measured
properties of the Flow (e.g., the total number of bytes for all
the Flow's packets) and usually contains characteristic properties
of the Flow (e.g., source IP address).

Metering Process

The Metering Process generates Flow Records. Inputs to the
process are packet headers, characteristics, and Packet Treatment
observed at one or more Observation Points.

The Metering Process consists of a set of functions that includes
packet header capturing, timestamping, sampling, classifying, and
maintaining Flow Records.

The maintenance of Flow Records may include creating new records,
updating existing ones, computing Flow statistics, deriving
further Flow properties, detecting Flow expiration, passing Flow
Records to the Exporting Process, and deleting Flow Records.

Exporting Process

The Exporting Process sends IPFIX Messages to one or more
Collecting Processes. The Flow Records in the Messages are
generated by one or more Metering Processes.

Exporter

A device that hosts one or more Exporting Processes is termed an
Exporter.

IPFIX Device

An IPFIX Device hosts at least one Exporting Process. It may host
further Exporting Processes and as well as arbitrary numbers of
Observation Points and Metering Processes.

Collecting Process

A Collecting Process receives IPFIX Messages from one or more
Exporting Processes. The Collecting Process might process or
store Flow Records received within these Messages, but such
actions are out of scope for this document.

Collector

A device that hosts one or more Collecting Processes is termed a
Collector.

Template

A Template is an ordered sequence of <type, length> pairs used to
completely specify the structure and semantics of a particular set
of information that needs to be communicated from an IPFIX Device
to a Collector. Each Template is uniquely identifiable by means
of a Template ID.

IPFIX Message

An IPFIX Message is a message originating that originates at the Exporting
Process
that and carries the IPFIX records of this Exporting Process Process,
and whose destination is a Collecting Process. An IPFIX Message
is encapsulated at the transport layer.

Message Header

The Message Header is the first part of an IPFIX Message, which Message; the
Message Header provides basic information about the message, such
as the IPFIX version, length of the message, message sequence
number, etc.

Template Record

A Template Record defines the structure and interpretation of
fields in a Data Record.

Data Record

A Data Record is a record that contains values of the parameters
corresponding to a Template Record.

Options Template Record

An Options Template Record is a Template Record that defines the
structure and interpretation of fields in a Data Record, including
defining how to scope the applicability of the Data Record.

Set

A Set is a collection of records that have a similar structure,
prefixed by a header. In an IPFIX Message, zero or more Sets
follow the Message Header. There are three different types of
Sets: Template Set, Sets, Options Template Set, Sets, and Data Set. Sets.

Template Set

A Template Set is a collection of one or more Template Records
that have been grouped together in an IPFIX Message.

Options Template Set

An Options Template Set is a collection of one or more Options
Template Records that have been grouped together in an IPFIX
Message.

Data Set

A Data Set is one or more Data Records, of the same type, that are
grouped together in an IPFIX Message. Each Data Record is
previously defined by a Template Record or an Options Template
Record.

Information Element

An Information Element is a protocol protocol- and encoding-independent
description of an attribute that may appear in an IPFIX Record.
The base set of
Information Elements making up the IPFIX
information model [RFC5102bis] are described defined in the IANA IPFIX "IPFIX Information Element Registry [IPFIX-IANA].
Elements" registry [IANA-IPFIX]. The type associated with an
Information Element indicates constraints on what it may contain
and also determines the valid encoding mechanisms for use in
IPFIX.

Transport Session

In the Stream Control Transmission Protocol (SCTP), the transport
session Transport
Session is known as the SCTP association, which is uniquely
identified by the SCTP endpoints [RFC4960]; in TCP, the transport
session Transport
Session is known as the TCP connection, which is uniquely
identified by the combination of IP addresses and TCP ports used.
In UDP, the transport session Transport Session is known as the UDP session, which
is uniquely identified by the combination of IP addresses and UDP
ports used.

2.1. Terminology Summary Table

Figure A shows a summary of IPFIX terminology.

+------------------+---------------------------------------------+
| | contents Contents |
| +--------------------+------------------------+
| Set | Template | Record |
+------------------+--------------------+------------------------+
| Data Set | / | Data Record(s) |
+------------------+--------------------+------------------------+
| Template Set | Template Record(s) | / |
+------------------+--------------------+------------------------+
| Options Template | Options Template | / |
| Set | Record(s) | |
+------------------+--------------------+------------------------+

Figure A: Terminology Summary Table

A Data Set is composed of Data Record(s). No Template Record is
included. A Template Record or an Options Template Record defines
the Data Record.

A Template Set contains only Template Record(s).

An Options Template Set contains only Options Template Record(s).

3. IPFIX Message Format

An IPFIX Message consists of a Message Header, followed by zero or
more Sets. The Sets can be any of the possible these three possible types:
Data Set, Template Set, or Options Template Set.

The format of the IPFIX Message is shown in Figure B.

+----------------------------------------------------+
| Message Header |
+----------------------------------------------------+
| Set |
+----------------------------------------------------+
| Set |
+----------------------------------------------------+
...
+----------------------------------------------------+
| Set |
+----------------------------------------------------+

Figure B: IPFIX Message Format
Following are some examples of IPFIX Messages:

1. An IPFIX Message consisting of interleaved Template, Data, and
Options Template Sets, as shown in Figure C. Here, Template and
Options Template Sets are transmitted "on demand", before the
first Data Set they define the whose structure of. they define.

+--------+--------------------------------------------------------+
| | +----------+ +---------+ +-----------+ +---------+ |
|Message | | Template | | Data | | Options | | Data | |
| Header | | Set | | Set | ... | Template | | Set | |
| | | | | | | Set | | | |
| | +----------+ +---------+ +-----------+ +---------+ |
+--------+--------------------------------------------------------+

Figure C: IPFIX Message, Message: Example 1

2. An IPFIX Message consisting entirely of Data Sets, sent after the
appropriate Template Records have been defined and transmitted to
the Collecting Process, as shown in Figure D.

+--------+----------------------------------------------+
| | +---------+ +---------+ +---------+ |
|Message | | Data | | Data | | Data | |
| Header | | Set | ... | Set | ... | Set | |
| | +---------+ +---------+ +---------+ |
+--------+----------------------------------------------+

Figure D: IPFIX Message, Message: Example 2

3. An IPFIX Message consisting entirely of Template and Options
Template Sets, as shown in Figure E. Such a message can be used
to define or redefine Templates and Options Templates in bulk.

+--------+-------------------------------------------------+
| | +----------+ +----------+ +----------+ |
|Message | | Template | | Template | | Options | |
| Header | | Set | ... | Set | ... | Template | |
| | | | | | | Set | |
| | +----------+ +----------+ +----------+ |
+--------+-------------------------------------------------+

Figure E: IPFIX Message, Message: Example 3

3.1. Message Header Format

The format of the IPFIX Message Header is shown in Figure F.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version Number | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Export Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Observation Domain ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure F: IPFIX Message Header Format

Each Message Header field is exported in network byte order. The
fields are defined as follows:

Version

Version of IPFIX to which this Message conforms. The value of
this field is 0x000a for the current version, incrementing by one
the version used in the NetFlow services export version 9
[RFC3954].

Length

Total length of the IPFIX Message, measured in octets, including
Message Header and Set(s).

Export Time

Time at which the IPFIX Message Header leaves the Exporter,
expressed in seconds since the UNIX epoch of 1 January 1970 at
00:00 UTC, encoded as an unsigned 32-bit integer.

Sequence Number

Incremental sequence counter modulo 2^32 of all IPFIX Data Records
sent in the current stream from the current Observation Domain by
the Exporting Process. Each SCTP Stream counts sequence numbers
separately, while all messages in a TCP connection or UDP
transport session
are considered to be part of the same stream. This value can be
used by the Collecting Process to identify whether any IPFIX Data
Records have been missed. Template and Options Template Records
do not increase the Sequence Number.

Observation Domain ID

A 32-bit identifier of the Observation Domain that is locally
unique to the Exporting Process. The Exporting Process uses the
Observation Domain ID to uniquely identify to the Collecting
Process the Observation Domain that metered the Flows. It is
RECOMMENDED that this identifier also be unique per IPFIX Device.
Collecting Processes SHOULD use the Transport Session and the
Observation Domain ID field to separate different export streams
originating from the same Exporter. The Observation Domain ID
SHOULD be 0 when no specific Observation Domain ID is relevant for
the entire IPFIX Message, for example, when exporting the
Exporting Process Statistics, or in the case of a hierarchy of
Collectors when aggregated Data Records are exported.

3.2. Field Specifier Format

Vendors need the ability to define proprietary Information Elements,
because, for example, they are delivering a pre-standards product, or
the Information Element is, is in some way, way commercially sensitive. This
section describes the Field Specifier format for both IANA-registered
Information Elements [IPFIX-IANA] [IANA-IPFIX] and enterprise-
specific enterprise-specific Information
Elements.

The Information Elements are identified by the Information Element
identifier. When the Enterprise bit is set to 0, the corresponding
Information Element appears in [IPFIX-IANA], [IANA-IPFIX], and the Enterprise
Number MUST NOT be present. When the Enterprise bit is set to 1, the
corresponding Information Element identifier identified an
enterprise-specific Information Element; the Enterprise Number MUST
be present. An example of this is shown in Section Appendix A.2.2.

The Field Specifier format is shown in Figure G.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E| Information Element ident. | Field Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure G: Field Specifier Format

Where:

Enterprise bit. This is the first bit of the Field Specifier. If
this bit is zero, the Information Element Identifier identifier identifies an
Information Element in [IPFIX-IANA], [IANA-IPFIX], and the four-octet Enterprise
Number field MUST NOT be present. If this bit is one, the
Information Element identifier identifies an enterprise-specific
Information Element, and the Enterprise Number field MUST be
present.

Information Element identifier

A numeric value that represents the Information Element. Refer to
[IPFIX-IANA].
[IANA-IPFIX].

Field Length

The length of the corresponding encoded Information Element, in
octets. Refer to [IPFIX-IANA]. [IANA-IPFIX]. The field length Field Length may be smaller
than that listed in [IPFIX-IANA] [IANA-IPFIX] if the reduced size reduced-size encoding is
used (see Section 6.2). The value 65535 is reserved for variable-
length Information Elements (see Section 7).

Enterprise Number

IANA enterprise number [PEN-IANA] [IANA-PEN] of the authority defining the
Information Element identifier in this Template Record.

3.3. Set and Set Header Format

A Set is a generic term for a collection of records that have a
similar structure. There are three different types of Sets: Template
Sets, Options Template Sets, and Data Sets. Each of these Sets
consists of a Set Header and one or more records. The Set Format and
the Set Header Format are defined in the following sections.

3.3.1. Set Format

A Set has the format shown in Figure H. The record types can be
either Template Records, Options Template Records, or Data Records.
The record types MUST NOT be mixed within a Set.

+--------------------------------------------------+
| Set Header |
+--------------------------------------------------+
| record |
+--------------------------------------------------+
| record |
+--------------------------------------------------+
...
+--------------------------------------------------+
| record |
+--------------------------------------------------+
| Padding (opt.) |
+--------------------------------------------------+

Figure H: Set Format

Set Header

The Set Header Format is defined in Section 3.3.2.

Record

One of the record Formats: formats: Template Record, Options Template
Record, or Data Record Format. format.

Padding

The Exporting Process MAY insert some padding octets, so that the
subsequent Set starts at an aligned boundary. For security
reasons, the padding octet(s) MUST be composed of octets with
value zero (0) valued
octets. (0). The padding length MUST be shorter than any
allowable record in this Set. If padding of the IPFIX Message is
desired in combination with very short records, then the padding
Information Element 'paddingOctets' can be used for padding
records such that their length is increased to a multiple of 4 or
8 octets. Because Template Sets are always 4-octet aligned by
definition, padding is only needed in the case of other alignments
alignments, e.g., on 8-octet boundaries.

3.3.2. Set Header Format

Every Set contains a common header. This header is defined in
Figure I.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure I: Set Header Format

Each Set Header field is exported in network format. The fields are
defined as follows:

Set ID

Identifies the Set. A value of 2 is reserved for Template Sets.
A value of 3 is reserved for Options Template Sets. Values from 4
to 255 are reserved for future use. Values 256 and above are used
for Data Sets. The Set ID values of 0 and 1 are not used, for
historical reasons [RFC3954].

Length

Total length of the Set, in octets, including the Set Header, all
records, and the optional padding. Because an individual Set MAY
contain multiple records, the Length value MUST be used to
determine the position of the next Set.

3.4. Record Format

IPFIX defines three record formats, as defined in the next sections:
the Template Record Format, format, the Options Template Record Format, format, and
the Data Record Format. format.

3.4.1. Template Record Format

One of the essential elements in the IPFIX record format is the
Template Record. Templates greatly enhance the flexibility of the
record format because they allow the Collecting Process to process
IPFIX Messages without necessarily knowing the interpretation of all
Data Records. A Template Record contains any combination of
IANA-assigned IANA-
assigned and/or enterprise-specific Information Element identifiers.

The format of the Template Record is shown in Figure J. It consists
of a Template Record Header and one or more Field Specifiers. The
definition of the Field
Specifiers is given are defined in Figure G above.

+--------------------------------------------------+
| Template Record Header |
+--------------------------------------------------+
| Field Specifier |
+--------------------------------------------------+
| Field Specifier |
+--------------------------------------------------+
...
+--------------------------------------------------+
| Field Specifier |
+--------------------------------------------------+

Figure J: Template Record Format

The format of the Template Record Header is shown in Figure K.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID (> 255) | Field Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure K: Template Record Header Format
The Template Record Header Field Definitions definitions are as follows:

Template ID

Each Template Record is given a unique Template ID in the range
256 to 65535. This uniqueness is local to the Transport Session
and Observation Domain that generated the Template ID. Since
Template IDs are used as Set IDs in the Sets they describe (see
section
Section 3.4.3), values 0-255 are reserved for special Set types
(e.g.
(e.g., Template Sets themselves), and Templates and Options
Templates (see section Section 3.4.2) cannot share Template IDs within a
Transport Session and Observation Domain. There are no
constraints regarding the order of the Template ID allocation. As
Exporting Processes are free to allocate Template IDs as they see
fit, Collecting Processes MUST NOT assume incremental Template
IDs, or anything about the contents of a Template based on its
Template ID alone.

Field Count

Number of fields in this Template Record.

The example in Figure L shows a Template Set with mixed IANA-assigned
and enterprise-specific Information Elements. It consists of a Set
Header, a Template Header, and several Field Specifiers.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 256 | Field Count = N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Information Element id. 1.1 | Field Length 1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number 1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Information Element id. 1.2 | Field Length 1.2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Information Element id. 1.N | Field Length 1.N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number 1.N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 257 | Field Count = M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Information Element id. 2.1 | Field Length 2.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Information Element id. 2.2 | Field Length 2.2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number 2.2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Information Element id. 2.M | Field Length 2.M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number 2.M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Padding (opt) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure L: Template Set Example

Information Element Identifiers id.s 1.2 and 2.1 appear in [IPFIX-IANA] [IANA-IPFIX]
(Enterprise bit = 0) and, therefore, and therefore do not need an Enterprise Number
to identify them.

3.4.2. Options Template Record Format

Thanks to the notion of scope, The Options Template Record gives the
Exporter the ability to provide additional information to the
Collector that would not be possible with Flow Records alone.

See Section 4 for specific Options Templates used for reporting
metadata about IPFIX Exporting and Metering Processes.

3.4.2.1. Scope

The scope, which is only available in the Options Template Set, gives
the context of the reported Information Elements in the Data Records.

The scope is one or more Information Elements, specified in the
Options Template Record. At a minimum, Collecting Processes SHOULD
support as
scope, at minimum, scope the observationDomainId, exportingProcessId,
meteringProcessId, templateId, lineCardId, exporterIPv4Address,
exporterIPv6Address, and ingressInterface Information Elements. The
IPFIX protocol doesn't prevent the use of any Information Elements
for scope. However, some Information Element types don't make sense
if specified as scope; for scope (for example, the counter Information Elements.
Elements).

The IPFIX Message Header already contains the Observation Domain ID.
If not zero, this Observation Domain ID can be considered as an
implicit scope for the Data Records in the IPFIX Message.

Multiple Scope Fields MAY be present in the Options Template Record,
in which case, case the composite scope is the combination of the scopes.
For example, if the two scopes are meteringProcessId and templateId,
the combined scope is this Template for this Metering Process. If a
different order of Scope Fields would result in a Record having a
different semantic meaning, then the order of Scope Fields MUST be
preserved by the Exporting Process. For example, in the context of
PSAMP [RFC5476], if the first scope defines the filtering function,
while the second scope defines the sampling function, the order of
the scope is important. Applying the sampling function first,
followed by the filtering function, would lead to potentially
different Data Records than applying the filtering function first,
followed by the sampling function.

3.4.2.2. Options Template Record Format

An Options Template Record contains any combination of IANA-assigned
and/or enterprise-specific Information Element identifiers.

The format of the Options Template Record is shown in Figure M. It
consists of an Options Template Record Header and one or more Field
Specifiers. The definition of the Field Specifiers is given are defined in Figure G above.

+--------------------------------------------------+
| Options Template Record Header |
+--------------------------------------------------+
| Field Specifier |
+--------------------------------------------------+
| Field Specifier |
+--------------------------------------------------+
...
+--------------------------------------------------+
| Field Specifier |
+--------------------------------------------------+

Figure M: Options Template Record Format

The format of the Options Template Record Header is shown in
Figure N.

Figure N: Options Template Record Header Format
The Options Template Record Header Field Definitions definitions are as follows:

Template ID

Each Options Template Record is given a unique Template ID in the
range 256 to 65535. This uniqueness is local to the Transport
Session and Observation Domain that generated the Template ID.
Since Template IDs are used as Set IDs in the sets they describe
(see section Section 3.4.3), values 0-255 are reserved for special Set
types (e.g. (e.g., Template Sets themselves), and Templates and Options
Templates cannot share Template IDs within a Transport Session and
Observation Domain. There are no constraints regarding the order
of the Template ID allocation. As Exporting Processes are free to
allocate Template IDs as they see fit, Collecting Processes MUST
NOT assume incremental Template IDs, or anything about the
contents of an Options Template based on its Template ID alone.

Field Count

Number of all fields in this Options Template Record, including
the Scope Fields.

Scope Field Count

Number of scope fields in this Options Template Record. The Scope
Fields are normal Fields Fields, except that they are interpreted as
scope at the Collector. A scope field count of N specifies that
the first N Field Specifiers in the Template Record are Scope
Fields. The Scope Field Count MUST NOT be zero.

The example in Figure O shows an Options Template Set with mixed
IANA-assigned and enterprise-specific Information Elements. It
consists of a Set Header, a an Options Template Header, and several
Field Specifiers.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 258 | Field Count = N + M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field Count = N |0| Scope 1 Infor. Element Id. id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length |0| Scope 2 Infor. Element Id. id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 2 Field Length | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |1| Scope N Infor. Element Id. id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope N Field Length | Scope N Enterprise Number ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Scope N Enterprise Number |1| Option 1 Infor. Element Id. id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option 1 Field Length | Option 1 Enterprise Number ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Option 1 Enterprise Number | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |0| Option M Infor. Element Id. id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option M Field Length | Padding (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure O: Options Template Set Example

3.4.3. Data Record Format

The Data Records are sent in Data Sets. The format of the Data
Record is shown in Figure P. It consists only of one or more Field
Values. The Template ID to which the Field Values belong is encoded
in the Set Header field "Set ID", i.e., "Set ID" = "Template ID".

+--------------------------------------------------+
| Field Value |
+--------------------------------------------------+
| Field Value |
+--------------------------------------------------+
...
+--------------------------------------------------+
| Field Value |
+--------------------------------------------------+

Figure P: Data Record Format

Note that Field Values do not necessarily have a length of 16 bits.
Field Values are encoded according to their data type as specified in
[RFC5102bis].
[RFC7012].

Interpretation of the Data Record format can be done only if the
Template Record corresponding to the Template ID is available at the
Collecting Process.

The example in Figure Q shows a Data Set. It consists of a Set
Header and several Field Values.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = Template ID | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 1 - Field Value 1 | Record 1 - Field Value 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 1 - Field Value 3 | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 2 - Field Value 1 | Record 2 - Field Value 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 2 - Field Value 3 | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 3 - Field Value 1 | Record 3 - Field Value 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 3 - Field Value 3 | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | Padding (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure Q: Data Set, containing Containing Data Records

4. Specific Reporting Requirements

Some specific Options Templates and Options Template Records are
necessary to provide extra information about the Flow Records and
about the Metering Process.

The Options Template and Options Template Records defined in these
subsections, which impose some constraints on the Metering Process
and Exporting Process implementations, MAY be implemented. If
implemented, the specific Options Templates SHOULD be implemented as
specified in these subsections.

The minimum set of Information Elements is always specified in these
Specific IPFIX Options Templates. Nevertheless, extra Information
Elements may be used in these specific Options Templates.

The Collecting Process MUST check the possible combinations of
Information Elements within the Options Template Records to correctly
interpret the following Options Templates.

4.1. The Metering Process Statistics Options Template

The Metering Process Statistics Options Template specifies the
structure of a Data Record for reporting Metering Process statistics.
It SHOULD contain the following Information Elements, as defined in
[IPFIX-IANA]
[IANA-IPFIX]:

(scope) observationDomainId

This Information Element MUST be defined as a Scope Field, Field and
MUST be present present, unless the Observation Domain ID of the
enclosing Message is non-zero.

(scope) meteringProcessId

If present, this Information Element MUST be defined as a Scope
Field.

exportedMessageTotalCount

exportedFlowRecordTotalCount

exportedOctetTotalCount

The Exporting Process SHOULD export the Data Record specified by the
Metering Process Statistics Options Template on a regular basis or
based on some export policy. This periodicity or export policy
SHOULD be configurable.

Note that if several Metering Processes are available on the Exporter
Observation Domain, the Information Element meteringProcessId MUST be
specified as an additional Scope Field.

4.2. The Metering Process Reliability Statistics Options Template

The Metering Process Reliability Statistics Options Template
specifies the structure of a Data Record for reporting lack of
reliability in the Metering Process. It SHOULD contain the following
Information
Elements Elements, as defined in [IPFIX-IANA]: [IANA-IPFIX]:

(scope) observationDomainId

This Information Element MUST be defined as a Scope Field, Field and
MUST be present present, unless the Observation Domain ID of the
enclosing Message is non-zero.

(scope) meteringProcessId

If present, this Information Element MUST be defined as a Scope
Field.

ignoredPacketTotalCount

ignoredOctetTotalCount

time first packet ignored

The timestamp of the first packet that was ignored by the
Metering Process. For this timestamp, any of the following
timestamp Information Elements can be used:

observationTimeSeconds,
observationTimeMilliseconds,
observationTimeMicroseconds, or
observationTimeNanoseconds.

time last packet ignored

The timestamp of the last packet that was ignored by the
Metering Process. For this timestamp, any of the following
timestamp Information Elements can be used:

observationTimeSeconds,
observationTimeMilliseconds,
observationTimeMicroseconds, or
observationTimeNanoseconds.

The Exporting Process SHOULD export the Data Record specified by the
Metering Process Reliability Statistics Options Template on a regular
basis or based on some export policy. This periodicity or export
policy SHOULD be configurable.

Note that if several Metering Processes are available on the Exporter
Observation Domain, the Information Element meteringProcessId MUST be
specified as an additional Scope Field.

Since the Metering Process Reliability Option Statistics Options Template
contains two identical timestamp Information Elements, and since the
order of the Information Elements in the Template Records is not
guaranteed, the Collecting Process interprets the time interval of
ignored packets as the range between the two values; see Section 5.2
for wraparound considerations.

4.3. The Exporting Process Reliability Statistics Options Template

The Exporting Process Reliability Statistics Options Template
specifies the structure of a Data Record for reporting lack of
reliability in the Exporting Process. It SHOULD contain the
following Information
Elements Elements, as defined in [IPFIX-IANA]: [IANA-IPFIX]:

(scope) Exporting Process ID Identifier

The identifier of the Exporting Process for which reliability
is reported. Any of the exporterIPv4Address,
exporterIPv6Address, or exportingProcessId Information Elements
can be used for this field. This Information Element MUST be
defined as a Scope Field.

notSentFlowTotalCount

notSentPacketTotalCount

notSentOctetTotalCount

time first flow dropped

The time at which the first Flow Record was dropped by the
Exporting Process. For this timestamp, any of the following
timestamp Information Elements can be used:

observationTimeSeconds,
observationTimeMilliseconds,
observationTimeMicroseconds, or
observationTimeNanoseconds.

time last flow dropped

The time at which the last Flow Record was dropped by the
Exporting Process. For this timestamp, any of the following
timestamp Information Elements can be used:

observationTimeSeconds,
observationTimeMilliseconds,
observationTimeMicroseconds, or
observationTimeNanoseconds.

The Exporting Process SHOULD export the Data Record specified by the
Exporting Process Reliability Statistics Options Template on a
regular basis or based on some export policy. This periodicity or
export policy SHOULD be configurable.

Since the Exporting Process Reliability Option Statistics Options Template
contains two identical timestamp Information Elements, and since the
order of the Information Elements in the Template Records is not
guaranteed, the Collecting Process interprets the time interval of ignored
dropped packets as the range between the two values; see Section 5.2
for wraparound considerations.

4.4. The Flow Keys Options Template

The Flow Keys Options Template specifies the structure of a Data
Record for reporting the Flow Keys of reported Flows. A Flow Keys
Data Record extends a particular Template Record that is referenced
by its templateId identifier. templateId. The Template Record is extended by specifying
which of the Information Elements contained in the corresponding Data
Records describe Flow properties that serve as Flow Keys of the
reported Flow.

The Flow Keys Options Template SHOULD contain the following
Information Elements that are Elements, as defined in [IPFIX-IANA]: [IANA-IPFIX]:

(scope) templateId

This Information Element MUST be defined as a Scope Field.

flowKeyIndicator

5. Timing Considerations

5.1

5.1. IPFIX Message Header Export Time and Flow Record Time

The IPFIX Message Header Export Time field is the time at which the
IPFIX Message Header leaves the Exporter, using the same encoding as
the dateTimeSeconds abstract data type [RFC5102bis], [RFC7012], i.e., expressed in
seconds since the UNIX epoch, 1 January 1970 at 00:00 UTC, encoded as
an unsigned 32-bit integer.

Certain time-related Information Elements may be expressed as an
offset from this Export Time. For example, Data Records requiring a
microsecond precision can export the flow start and end times with
the flowStartMicroseconds and flowEndMicroseconds Information
Elements, which encode the absolute time in microseconds in terms of
the NTP epoch, 1 January 1900 at 00:00 UTC, in a 64-bit field. An
alternate solution is to export the flowStartDeltaMicroseconds and
flowEndDeltaMicroseconds Information Elements in the Data Record,
which respectively report the flow start and end time as negative
offsets from the Export Time, as an unsigned 32-bit integer. This
latter solution lowers the export bandwidth requirement, saving
four bytes per timestamp, while increasing the load on the Exporter,
as the Exporting Process must calculate the
flowStartDeltaMicroseconds and flowEndDeltaMicroseconds of every
single Data Record before exporting the IPFIX Message.

It must be noted that timestamps based on the Export Time impose some
time constraints on the Data Records contained within the IPFIX
Message. In the example of flowStartDeltaMicroseconds and
flowEndDeltaMicroseconds Information Elements, the Data Record can
only contain records with timestamps within 71 minutes of the Export
Time. Otherwise, the 32-bit counter would not be sufficient to
contain the flow start time offset.

5.2

5.2. Supporting Timestamp Wraparound

The dateTimeSeconds abstract data type [RFC5102bis] [RFC7012] and the Export Time
Message Header field (Section 3.1) are encoded as 32-bit unsigned
integers, expressed as seconds since the UNIX epoch, 1 January 1970
at 00:00 UTC, as defined in [POSIX.1]. These values will wrap around
on 7 February 2106 at 06:28:16 UTC.

In order to support continued use of the IPFIX Protocol protocol beyond this
date, Exporting Processes SHOULD export dateTimeSeconds values and
the Export Time Message Header field as the number of seconds since
the UNIX epoch, 1 January 1970 at 00:00 UTC, modulo 2^32. Collecting
Processes SHOULD use the current date, or other contextual
information, to properly interpret dateTimeSeconds values and the
Export Time Message Header field.

There are similar considerations for the NTP-based
dateTimeMicroseconds and dateTimeNanoseconds abstract data types
[RFC5102bis].
[RFC7012]. Exporting Processes SHOULD export dateTimeMicroseconds
and dateTimeNanoseconds values as if the NTP Era era [RFC5905] is
implicit; Collecting Processes SHOULD use the current date, or other
contextual information, to determine the NTP Era era in order to properly
interpret dateTimeMicroseconds and dateTimeNanoseconds values in
received Data Records.

The dateTimeMilliseconds abstract data type will wrap around in
approximately 500 billion years; the specification of the behavior of
this abstract data type after that time is left as a subject of a
future revision of this specification.

The long-term storage of files [RFC5655] for archival purposes is
affected by timestamp wraparound, as the use of the current date to
interpret timestamp values in files stored on the order of multiple
decades in the past may lead to incorrect values; therefore, it is
RECOMMENDED that such files be stored with contextual information to
assist in the interpretation of these timestamps.

6. Linkage with the Information Model

As with values in the IPFIX Message Header and Set Header, values of
all Information Elements [RFC5102bis], [RFC7012], except for those of the string
and octetArray data types, are encoded in canonical format in network
byte order (also known as big-endian byte ordering).

6.1. Encoding of IPFIX Data Types

The following sections define the encoding of the data types
specified in [RFC5102bis]. [RFC7012].

6.1.1. Integral Data Types

Integral data types -- octet, signed8, unsigned8, unsigned16, signed16, unsigned32, unsigned64,
signed8, signed16, signed32, signed64, and unsigned64 signed64 -- MUST be encoded using
the default canonical format in network byte order. Signed
Integral integral
data types are represented in two's complement notation.

6.1.2. Address Types

Address types -- macAddress, ipv4Address, and ipv6Address -- MUST be
encoded the same way as the integral data types, as six, four, and
sixteen octets in network byte order, respectively.

6.1.3. float32

The float32 data type MUST be encoded as an IEEE single-precision
32-bit binary32 floating point-type,
point type as specified in [IEEE.754.1985], [IEEE.754.2008], in network byte order as
specified in Setion Section 3.6 of [RFC1014]. Note that on little-endian
machines, byte swapping of the native representation is necessary
before export. Note that the method for doing this may be
implementation platform dependent.

6.1.4. float64

The float64 data type MUST be encoded as an IEEE double-precision
64-bit binary64 floating point-type,
point type as specified in [IEEE.754.1985], [IEEE.754.2008], in network byte order as
specified in Section 3.7 of [RFC1014]. Note that on little-endian
machines, byte swapping of the native representation is necessary
before export. Note that the method for doing this may be
implementation platform dependent.

6.1.5. boolean

The boolean data type is specified according to the TruthValue in
[RFC2579]. It is encoded as a single-octet integer, as in integer per
Section
6.1.1., 6.1.1, with the value 1 for true and a value 2 for false.
Every other value is undefined.

6.1.6. string and octetArray

The "string" data type string represents a finite length finite-length string of valid
characters of the Unicode character encoding set. The string data
type MUST be encoded in UTF-8 [RFC3629] format. The string is sent
as an array of zero or more octets using an Information Element of
fixed or variable length. IPFIX Exporting Processes MUST NOT send
IPFIX Messages containing ill-formed UTF-8 string values for
Information Elements of the string data type; Collecting Processes
SHOULD detect and ignore such values. See [UTF8-EXPLOIT] for
background on this issue.

The octetArray data type octetArray has no encoding rules; it represents a raw
array of zero or more octets, with the interpretation of the octets
defined in the Information Element definition.

6.1.7. dateTimeSeconds

The dateTimeSeconds data type dateTimeSeconds is an unsigned 32-bit integer in
network byte order containing the number of seconds since the UNIX
epoch, 1 January 1970 at 00:00 UTC, as defined in [POSIX.1].
dateTimeSeconds is encoded identically to the IPFIX Message Header
Export Time field. It can represent dates between 1 January 1970 and
7 February 2106 without wraparound; see section Section 5.2 for wraparound
considerations.

6.1.8. dateTimeMilliseconds

The dateTimeMilliseconds data type dateTimeMilliseconds is an unsigned 64-bit integer in
network byte order, order containing the number of milliseconds since the
UNIX epoch, 1 January 1970 at 00:00 UTC, as defined in [POSIX.1]. It
can represent dates beginning on 1 January 1970 and for approximately
the next 500 billion years without wraparound.

6.1.9

6.1.9. dateTimeMicroseconds

The dateTimeMicroseconds data type dateTimeMicroseconds is a 64-bit field encoded
according to the NTP Timestamp format as defined in section Section 6 of
[RFC5905]. This field is made up of two unsigned 32-bit integers in
network byte order, order: Seconds and Fraction. The Seconds field is the
number of seconds since the NTP epoch, 1 January 1900 at 00:00 UTC.

The Fraction field is the fractional number of seconds in units of
1/(2^32) seconds (approximately 233 picoseconds). It can represent
dates beginning between 1 January 1900 and 8 February 2036 in the current
NTP Era; era; see section Section 5.2 for wraparound considerations.

Note that dateTimeMicroseconds and dateTimeNanoseconds share an
identical encoding. The dateTimeMicroseconds data type is intended
only to represent timestamps of microsecond precision. Therefore,
the bottom 11 bits of the fraction Fraction field SHOULD be zero and MUST
be ignored for all Information Elements of this data type
(as 2^11 x 233 picoseconds = .477 microseconds).

6.1.10

6.1.10. dateTimeNanoseconds

The dateTimeNanoseconds data type dateTimeNanoseconds is a 64-bit field encoded according
to the NTP Timestamp format as defined in section Section 6 of [RFC5905].
This field is made up of two unsigned 32-bit integers in network byte
order,
order: Seconds and Fraction. The Seconds field is the number of
seconds since the NTP epoch, 1 January 1900 at 00:00 UTC. The
Fraction field is the fractional number of seconds in units of
1/(2^32) seconds (approximately 233 picoseconds). It can represent
dates beginning between 1 January 1900 and 8 February 2036 in the current
NTP Era; era; see section Section 5.2 for wraparound considerations.

Note that dateTimeMicroseconds and dateTimeNanoseconds share an
identical encoding. There is no restriction on the interpretation of
the Fraction field for the dateTimeNanoseconds data type.

6.2. Reduced Size Reduced-Size Encoding

Information Elements encoded as signed, unsigned, or float data types
MAY be encoded using fewer octets than those implied by their type in
the information model definition, based on the assumption that the
smaller size is sufficient to carry any value the Exporter may need
to deliver. This reduces the network bandwidth requirement between
the Exporter and the Collector. Note that the Information Element
definitions [IPFIX-IANA] [IANA-IPFIX] always define the maximum encoding size.

For instance, the information model defines octetDeltaCount as an
unsigned64 type, which would require 64 bits. However, if the
Exporter will never locally encounter the need to send a value larger
than 4294967295, it may chose choose to send the value instead as an
unsigned32. unsigned32
instead.

This behavior is indicated by the Exporter by specifying a size in
the Template with a smaller length than that associated with the
assigned type of the Information Element. In the example above, the
Exporter would place a length of 4 versus 8 in the Template.

Reduced size

Reduced-size encoding MAY be be applied to the following integer types:
unsigned64, signed64, unsigned32, signed32, unsigned16, and signed16.
The signed versus unsigned property of the reported value MUST be
preserved. The reduction in size can be to any number of octets
smaller than the original type if the data value still fits, i.e., so
that only leading zeroes are dropped. For example, an unsigned64 can
be reduced in size to 7, 6, 5, 4, 3, 2, or 1 octet(s).

Reduced size

Reduced-size encoding MAY be used to reduce float64 to float32. The
float32 not only has a reduced number range, but range but, due to the smaller
mantissa, is also less precise. In this case, the float64 would be
reduced in size to 4 octets.

Reduced size

Reduced-size encoding MUST NOT be applied to any other data type
defined in [RFC5102bis] [RFC7012] that implies a fixed length, as these types
either have internal structure (such as ipv4Address or
dateTimeMicroseconds) or restricted ranges that are not suitable for
reduced length
reduced-size encoding (such as dateTimeMilliseconds).

Information Elements of type octetArray and string may be exported
using any length, subject to restrictions on length specific to each
Information Element, as noted in that Information Element's
description.

7. Variable-Length Information Element

The IPFIX Template mechanism is optimized for fixed-length
Information Elements [RFC5102bis]. [RFC7012]. Where an Information Element has a
variable length, the following mechanism MUST be used to carry the
length information for both the IANA IANA-assigned and enterprise-specific
Information Elements.

In the Template Set, the Information Element Field Length is recorded
as 65535. This reserved length value notifies the Collecting Process
that the length value of the Information Element will be carried in
the Information Element content itself.

In most cases, the length of the Information Element will be less
than 255 octets. The following length-encoding mechanism optimizes
the overhead of carrying the Information Element length in this
majority more
common case. The length is carried in the octet before the
Information Element, as shown in Figure R.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (< 255)| Information Element |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... continuing as needed |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure R: Variable-Length Information Element (length (IE)
(Length < 255 octets) Octets)

The length may also be encoded into 3 octets before the Information
element
Element, allowing the length of the Information Element to be greater
than or equal to 255 octets. In this case, the first octet of the
Length field MUST be 255, and the length is carried in the second and
third octets, as shown in Figure S.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | Length (0 to 65535) | IE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... continuing as needed |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure S: Variable-Length Information Element (length (IE)
(Length 0 to 65535
octets) Octets)

The octets carrying the length (either the first or the first
three octets) MUST NOT be included in the length of the Information
Element.

8. Template Management

This section describes the management of Templates and Options
Templates at the Exporting and Collecting Processes. The goal of
Template management is to ensure, to the extent possible, that the
Exporting Process and Collecting Process have a consistent view of
the Templates and Options Templates used to encode and decode the
Records sent from the Exporting Process to the Collecting Process.

Achieving this goal is complicated somewhat by two factors: 1. 1) the
need to support the reuse of Template IDs within a Transport Session
and 2. 2) the need to support unreliable transmission for Templates when
UDP is used as the transport protocol for IPFIX Messages.

The Template Management mechanisms defined in this section apply to
the export of IPFIX Messages export on SCTP, TCP, or UDP. Additional
considerations specific to SCTP and UDP transport are given in sections
Sections 8.3 and 8.4, respectively.

The Exporting Process assigns and maintains Template IDs per
Transport Session and Observation Domain. A newly created Template
Record is assigned an unused Template ID by the Exporting Process.
The Collecting Process MUST store all received Template Record
information for the duration of each Transport Session until reuse or
withdrawal as described in section Section 8.1, or expiry over UDP as
described in section Section 8.4, so that it can interpret the corresponding
Data Records.

The Collecting Process MUST NOT assume that the Template IDs from a
given Exporting Process refer to the same Templates as they did in
previous Transport Sessions from the same Exporting Process; a
Collecting Process MUST NOT use Templates from one Transport Session
to decode Data Sets in a subsequent Transport Session.

If a specific Information Element is required by a Template, Template but is
not present in observed packets, the Exporting Process MAY choose to
export Flow Records without this Information Element in a Data Record
described by a new Template.

If an Information Element is required more than once in a Template,
the different occurrences of this Information Element SHOULD follow
the logical order of their treatments by the Metering Process. For
example, if a selected packet goes through two hash functions, and if
the two hash values are sent within a single Template, the first
occurrence of the hash value should belong to the first hash function
in the Metering Process. For example, when exporting the two source
IP addresses of an IPv4-in-IPv4 packet, the first sourceIPv4Address
Information Element occurrence should be the IPv4 address of the
outer header, while the second occurrence should be the address of
the inner header. Collecting Processes MUST properly handle
Templates with multiple identical Information Elements.

The Exporting Process SHOULD transmit the Template Set and Options
Template Set in advance of any Data Sets that use that (Options)
Template ID, to help ensure that the Collector has the Template
Record before receiving the first Data Record. Data Records that
correspond to a Template Record MAY appear in the same and/or
subsequent IPFIX Message(s). However, a Collecting Process MUST NOT
assume that the Data Set and the associated Template Set (or Options
Template Set) are exported in the same IPFIX Message.

Though a Collecting Process normally receives Template Records from
the Exporting Process before receiving Data Records, this is not
always the case, e.g. e.g., in the case of reordering or Collecting
Process restart over UDP. In these cases, the Collecting Process MAY
buffer Data Records for which it has no Templates Templates, to wait for
Template Records describing them; however, note that in the presence
of Template withdrawal and redefinition (Section 8.1) this may lead
to incorrect interpretation of Data Records.

Different Observation Domains within a Transport Session MAY use the
same Template ID value to refer to different Templates; Collecting
Processes MUST properly handle this case.

Options Templates and Templates which that are related or interdependent
(e.g.
(e.g., by sharing common properties as described in [RFC5473]) SHOULD
be sent together in the same IPFIX Message.

8.1. Template Withdrawal and Redefinition

Templates that will not be used further by an Exporting Process MAY
be withdrawn by sending a Template Withdrawal. After receiving a
Template Withdrawal, a Collecting Process MUST stop using the
Template to interpret subsequently-exported subsequently exported Data Sets. Note that
this mechanism does not apply when UDP is used to transport IPFIX
Messages; for this that case, see Section 8.4.

A Template Withdrawal consists of a Template Record for the Template
ID to be withdrawn, with a Field Count of 0. The format of a
Template Withdrawal is shown in Figure T.

Figure T: Template Withdrawal Format
The Set ID field MUST contain the value 2 for Template Set Withdrawal
and
or the value 3 for Options Template Set Withdrawal. Multiple
Template IDs MAY be withdrawn with a single Template Withdrawal, Withdrawal; in
that case, padding MAY be used.

Template Withdrawals MAY appear interleaved with Template Sets,
Options Template Sets, and Data Sets within an IPFIX Message. In
this case, the Templates and Template Withdrawals shall be taken to take
interpreted as taking effect in the order in which they appear in the
IPFIX Message. An Exporting Process SHOULD NOT send a Template
Withdrawal until sufficient time has elapsed to allow receipt and
processing of any Data Records described by the withdrawn Templates;
see Section 8.2 on for details regarding the sequencing of Template
management actions.

The end of a Transport Session implicitly withdraws all the Templates
used within the Transport Session, and Templates must be resent
during subsequent Transport Sessions between an Exporting Process and
Collecting Process. This applies to SCTP and TCP only; see sections
Sections 8.4 and 10.3.4 for a discussion discussions of Transport Session and
Template lifetime over UDP.

All Templates for a given Observation Domain MAY also be withdrawn
using an All Templates Withdrawal, as shown in Figure U. All Options
Templates for a given Observation Domain MAY likewise be withdrawn
using an All Options Templates Withdrawal, as shown in Figure 3. V.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 2 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 2 | Field Count = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure U: All Templates Withdrawal Set Format

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 3 | Field Count = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure V: All Options Templates Withdrawal Set Format
Template IDs MAY be reused for new Templates by sending a new
Template Record or Options Template Record for a given Template ID
after withdrawing the Template.

If a Collecting Process receives a Template Withdrawal for a Template
or Options Template it does not presently have stored, this indicates
a malfunctioning or improperly-implemented improperly implemented Exporting Process. The
continued receipt and interpretation of Data Records is are still
possible, but it the Collecting Process MUST ignore the Template
Withdrawal and SHOULD log the error.

If a Collecting Process receives a new Template Record or Options
Template Record for an already-allocated Template ID, and that
Template or Options Template is identical to the already-received
Template or Options Template, it SHOULD log the retransmission;
however, this is not an error condition, as it does not affect the
interpretation of data records. Data Records.

If a Collecting Process receives a new Template Record or Options
Template Record for an already-allocated Template ID, and that
Template or Options Template is different from the already-received
Template or Options Template, this indicates a malfunctioning or
improperly-implemented
improperly implemented Exporting Process. The continued receipt and
unambiguous interpretation of Data Records for this Template ID is are
no longer possible, and the Collecting Process SHOULD log the error; further error.
Further Collecting Process actions are out of scope of for this
specification.

8.2

8.2. Sequencing Template Management Actions

Since there is no guarantee of the ordering of exported IPFIX
Messages across SCTP Streams or over UDP, an Exporting Process MUST
sequence all Template management actions (i.e., Template Records
defining new Templates and Template Withdrawals withdrawing them)
using the Export Time field in the IPFIX Message Header.

An Exporting Process MUST NOT export a Data Set described by a new
Template in an IPFIX Message with an Export Time before the Export
Time of the IPFIX Message containing that Template. If a new
Template and a Data Set described by it appear in the same IPFIX
Message, the Template Set containing the Template MUST appear before
the Data Set in the Message.

An Exporting Process MUST NOT export any Data Sets described by a
withdrawn Template in IPFIX Messages with an Export Time after the
Export Time of the IPFIX Message containing the Template Withdrawal
withdrawing that Template.

Put another way, a Template describes Data Records contained in IPFIX
messages
Messages when the export time Export Time of such messages is between a specific
start and end time, inclusive. The start time is the Export Time of
the IPFIX Message containing the Template record. Record. The end time is
one of two times. If times: if the template is withdrawn during the session,
then it is the Export Time of the IPFIX message Message containing the
Template Withdrawal for the template. Otherwise, template; otherwise, it is the end of the
Transport Session.

Even if sent in-order, in order, IPFIX Messages containing Template management
actions could arrive at the Collecting Process out-of-order, i.e. out of order, i.e., if
sent via UDP or via different SCTP streams. Streams. Given this, Template
Withdrawals and subsequent reuse of Template IDs can significantly
complicate the problem of determining Template lifetimes at the
Collecting Process. A Collecting Process MAY implement a buffer and
use Export Time information to disambiguate the order of Template
management actions. This buffer, if implemented, SHOULD be
configurable to impart a delay on the order of the maximum reordering
delay experienced at the Collecting Process. Note, in this case,
that the Collecting Process' Process's clock is irrelevant: it is only
comparing the Export Times of Messages to each other.

8.3. Additional considerations Considerations for Template Management over SCTP

The specifications in this section apply only to SCTP; in case cases of
contradiction with specifications in Sections Section 8 or Section 8.1, this
section takes precedence.

Template Sets and Options Template Sets MAY be sent on any SCTP
stream.
Stream. Data Sets sent on a given SCTP stream Stream MAY be represented by
Template Records exported on any SCTP stream. Stream.

Template Sets and Options Template Sets MUST be sent reliably, using
SCTP ordered delivery.

Template Withdrawals MAY be sent on any SCTP stream. Stream. Template
Withdrawals MUST be sent reliably, using SCTP ordered delivery.
Template IDs MAY be reused by sending a Template Withdrawal and/or a
new Template Record on a different SCTP stream Stream than the stream on
which the original Template was sent.

Additional Template Management considerations are given provided in
[RFC6526], which specifies an extension to explicitly link Templates
with SCTP
streams. Streams. In exchange for more restrictive rules on the
assignment of Template Records to SCTP streams, Streams, this extension allows
fast, reliable reuse of Template IDs and estimation of Data Record
loss per Template.

8.4. Additional considerations Considerations for Template Management over UDP

The specifications in this section apply only to UDP; in case cases of
contradiction with specifications in Sections Section 8 or Section 8.1, this
section takes precedence.

Since UDP provides no method for reliable transmission of Templates,
Exporting Processes using UDP as the Transport Protocol transport protocol MUST
periodically retransmit each active Template at regular intervals.
The Template retransmission interval MUST be configurable, as via the configurable via, for
example, the templateRefreshTimeout and optionsTemplateRefreshTimeout
parameters as defined in [RFC6728]. Default settings for these
values are deployment- and application-specific.

Before exporting any Data Records described by a given Template
Record or Options Template Record, especially in the case of Template
ID reuse as described in section Section 8.1, the Exporting Process SHOULD
send multiple copies of the Template Record in a separate IPFIX
Message, in order to help ensure that the Collecting Process has
received it.

In order to minimize resource requirements for Templates which that are no
longer being used by the Exporting Process, the Collecting Process
MAY associate a lifetime with each Template received in a UDP Transport
Session. Templates not refreshed by the Exporting Process within the
lifetime can then be discarded by the Collecting Process. The
Template lifetime at the Collecting Process MAY be exposed by a
configuration parameter, parameter or MAY be derived from observation of the
interval of periodic Template retransmissions from the Exporting
Process. In this latter case, the Template lifetime SHOULD default
to at least 3 times the observed retransmission rate.

Template Withdrawals (Section 8.1) MUST NOT be sent by Exporting
Processes exporting via UDP, UDP and MUST be ignored by Collecting
Processes collecting via UDP. Template IDs MAY be reused by
Exporting Processes by exporting a new Template for the Template ID
after waiting at least 3 times the retransmission delay. Note that
Template ID reuse may lead to incorrect interpretation of Data
Records if the retransmission and lifetime are not properly
configured.

When a Collecting Process receives a new Template Record or Options
Template Record via UDP for an already-allocated Template ID, and
that Template or Options Template is identical to the already-
received Template or Options Template, it SHOULD NOT log the
retransmission, as this is the normal operation of Template refresh
over UDP.

When a Collecting Process receives a new Template Record or Options
Template Record for an already-allocated Template ID, and that
Template or Options Template is different from the already-received
Template or Options Template, the Collecting Process MUST replace the
Template or Options Template for that Template ID with the newly- newly
received Template or Options Template. This is the normal operation
of Template ID reuse over UDP.

As Template IDs are unique per UDP session and per Observation
Domain, at any given time, the Collecting Process SHOULD maintain the
following for all the current Template Records and Options Template
Records: <IPFIX Device, Exporter source UDP port, Collector IP
address, Collector destination UDP port, Observation Domain ID,
Template ID, Template Definition, Last Received>.

9. The Collecting Process's Side

This section describes the handling of the IPFIX Protocol protocol at the
Collecting Process common to all Transport Protocols. transport protocols. Additional
considerations for SCTP and UDP are given provided in Sections 9.2 and 9.3 9.3,
respectively. Template management at Collecting Processes is covered
in Section 8.

The Collecting Process MUST listen for association requests /
connections to start new Transport Sessions from the Exporting
Process.

The Collecting Process MUST note the Information Element identifier
of any Information Element that it does not understand and MAY
discard that Information Element from received Data Records.

The Collecting Process MUST accept padding in Data Records and
Template Records. The padding size is the Set Length minus the size
of the Set Header (4 octets for the Set ID and the Set Length),
modulo the minimum Record size deduced from the Template Record.

The IPFIX protocol has a Sequence Number field in the Export header
that increases with the number of IPFIX Data Records in the IPFIX
Message. A Collector can detect out-of-sequence, dropped, or
duplicate IPFIX Messages by tracking the Sequence Number. A
Collector SHOULD provide a logging mechanism for tracking out-of-
sequence IPFIX Messages. Such out-of-sequence IPFIX Messages may be
due to Exporter resource exhaustion where it cannot transmit messages
at their creation rate, an Exporting Process reset, congestion on the
network link between the Exporter and Collector, Collector resource
exhaustion where it cannot process the IPFIX Messages at their
arrival rate, out-of-order packet reception, duplicate packet
reception, or an attacker injecting false messages.

9.1. Collecting Process handling Handling of malformed Malformed IPFIX Messages

If the Collecting Process receives a malformed IPFIX Message Message, it MUST
discard the IPFIX Message and SHOULD log the error. A malformed
IPFIX Message is one that cannot be interpreted due to nonsensical
length values (e.g., a variable length variable-length Information Element longer
than its enclosing Set, a Set longer than its enclosing IPFIX
Message, or an IPFIX Message shorter than an IPFIX Message Header) or
a reserved Version value (which may indicate that a future version of
IPFIX is being used for export, export but practically in practice occurs most often when
non-IPFIX data is sent to an IPFIX Collecting Process). Note that
non-zero Set padding does not constitute a malformed IPFIX Message.

As the most likely cause of malformed IPFIX Messages is a poorly
implemented Exporting Process, or the sending of non-IPFIX data to an
IPFIX Collecting Process, human intervention is likely necessary to
correct the issue. In the meantime, the Collecting Process MAY
attempt to rectify the situation any way it sees fit, including:

- terminating the TCP connection or SCTP connection

- using the receiver window to reduce network load from the
malfunctioning Exporting Process

- buffering and saving malformed IPFIX Message(s) to assist in
diagnosis

- attempting to resynchronize the stream, e.g. e.g., as described in section
Section 10.3 of [RFC5655]

Resynchronization should only be attempted if there the Collecting Process
has reason to believe that the error is transient. On the other
hand, the Collecting Process SHOULD stop processing IPFIX Messages
from clearly malfunctioning Exporting Processes (e.g., those from
which the last few IPFIX Messages have been malformed).

9.2. Additional considerations Considerations for SCTP Collecting Processes

As an Exporting Process may request and support more than one stream
per SCTP association, the Collecting Process MUST support the opening
of multiple SCTP streams. Streams.

9.3. Additional considerations Considerations for UDP Collecting Processes

A Transport Session for IPFIX Messages transported over UDP is
defined from the point of view of the Exporting Process, Process and roughly
corresponds to the time during which a given Exporting Process sends
IPFIX Messages over UDP to a given Collecting Process. Since this is
difficult to detect at the Collecting Process, the Collecting Process
MAY discard all Transport Session state after no IPFIX Messages are
received from a given Exporting Process within a given Transport
Session during a configurable idle timeout.

The Collecting Process SHOULD accept Data Records without the
associated Template Record (or other definitions such as Common
Properties) required to decode the Data Record. If the Template
Records or other definitions have not been received at the time Data
Records are received, the Collecting Process MAY store the Data
Records for a short period of time and decode them after the Template
Records or other definitions are received, comparing Export Times of
IPFIX Messages containing the Template Records with those containing
the Data Records as discussed in Section 8.2. Note that this
mechanism may lead to incorrectly interpreted records in the presence
of Template ID reuse or other identifiers with limited lifetimes.

10. Transport Protocol

The IPFIX Protocol Specification has been designed to be transport
protocol independent. Note that the Exporter can export to multiple
Collecting Processes using independent transport protocols.

The IPFIX Message Header 16-bit Length field limits the length of an
IPFIX Message to 65535 octets, including the header. A Collecting
Process MUST be able to handle IPFIX Message lengths of up to
65535 octets.

While an Exporting Process or Collecting Process may support multiple
transport protocols, Transport Sessions are bound to a transport
protocol. Transport Session state MUST NOT be migrated by an
Exporting Process or Collecting Process among Transport Sessions
using different transport protocols between the same Exporting
Process and Collecting Process pair. In other words, an Exporting
Process supporting multiple transport protocols is conceptually
multiple Exporting Processes, one per supported transport protocol.
Likewise, a Collecting Process supporting multiple transport
protocols is conceptually multiple Collecting Processes, one per
supported Transport Protocol. transport protocol.

10.1. Transport Compliance and Transport Usage

SCTP [RFC4960] using the PR-SCTP Partially Reliable SCTP (PR-SCTP) extension
as specified in [RFC3758] MUST be implemented by all compliant
implementations. UDP [UDP] MAY also be implemented by compliant
implementations. TCP [TCP] MAY also be implemented by compliant
implementations.

SCTP should be used in deployments where Exporters and Collectors are
communicating over links that are susceptible to congestion. SCTP is
capable of providing any required degree of reliability when used
with the PR-SCTP extension.

TCP may be used in deployments where Exporters and Collectors
communicate over links that are susceptible to congestion, but SCTP
is preferred preferred, due to its ability to limit back pressure on Exporters
and its message versus stream message-versus-stream orientation.

UDP may be used, although it is not a congestion-aware protocol.
However, in this case the IPFIX traffic between the Exporter and
Collector must be separately contained or provisioned to minimize the
risk of congestion-related loss.

By default, the Collecting Process listens for connections on SCTP,
TCP, and/or UDP port 4739. By default, the Collecting Process
listens for secure connections on SCTP, TCP, and/or UDP port 4740
(refer to the Security Considerations section). By default, the
Exporting Process attempts to connect to one of these ports. It MUST
be possible to configure both the Exporting and Collecting Processes
to use different ports than the default.

10.2. SCTP

This section describes how IPFIX is transported over SCTP [RFC4960]
using the PR-SCTP [RFC3758] extension.

10.2.1. Congestion Avoidance

The

SCTP transport protocol provides the required level of congestion avoidance by design.

SCTP detects congestion in the end-to-end path between the IPFIX
Exporting Process and the IPFIX Collecting Process, and limits the
transfer rate accordingly. When an IPFIX Exporting Process has
records to export, export but detects that transmission by SCTP is
temporarily impossible, it can either wait until sending is possible
again,
again or it can decide to drop the record. In the latter case, the dropped
export data SHOULD be accounted for, so that the amount of dropped
export data can be reported using the mechanism described in
Section 4.3.

10.2.2. Reliability

The SCTP transport protocol is by default reliable, reliable but has the
capability to deliver messages with partial reliability [RFC3758].

Using reliable SCTP messages for the IPFIX export is not in itself a
guarantee that all Data Records will be delivered. If there is
congestion on the link from the Exporting Process to the Collecting
Process, or if a significant number of retransmissions are required,
the send queues on the Exporting Process may fill up; the Exporting
Process MAY either suspend, export, or discard the IPFIX Messages.
If Data Records are discarded discarded, the IPFIX Sequence Numbers used for
export MUST reflect the loss of data.

10.2.3. MTU

SCTP provides the required IPFIX Message fragmentation service based
on path Path MTU (PMTU) discovery.

10.2.4. Association Establishment and Shutdown

The IPFIX Exporting Process initiates an SCTP association with the
IPFIX Collecting Process. The Exporting Process MAY establish more
than one association (connection "bundle" in SCTP terminology) to the
Collecting Process.

An Exporting Process MAY support more than one active association to
different Collecting Processes (including the case of different
Collecting Processes on the same host).

When an Exporting Process is shut down, it SHOULD shut down the SCTP
association.

When a Collecting Process no longer wants to receive IPFIX Messages,
it SHOULD shut down its end of the association. The Collecting
Process SHOULD continue to receive and process IPFIX Messages until
the Exporting Process has closed its end of the association.

When a Collecting Process detects that the SCTP association has been
abnormally terminated, it MUST continue to listen for a new
association establishment.

When an Exporting Process detects that the SCTP association to the
Collecting Process is abnormally terminated, it SHOULD try to
re-establish the association.

Association timeouts SHOULD be configurable.

10.2.5. Failover

If the Collecting Process does not acknowledge an attempt by the
Exporting Process to establish an association, SCTP will
automatically retry association establishment using exponential
backoff. The Exporter MAY log an alarm if the underlying SCTP
association establishment times out; this timeout should be
configurable on the Exporter.

The Exporting Process MAY open a backup SCTP association to a
Collecting Process in advance, if it supports Collecting Process
failover.

10.2.6. Streams

An Exporting Process MAY request more than one SCTP stream Stream per
association. Each of these streams may be used for the transmission
of IPFIX Messages containing Data Sets, Template Sets, and/or Options
Template Sets.

Depending on the requirements of the application, the Exporting
Process may send Data Sets with full or partial reliability, using
ordered or out-of-order delivery, over any SCTP stream Stream established
during SCTP Association association setup.

An IPFIX Exporting Process MAY use any PR-SCTP Service Definition service definition as
per Section 4 of the PR-SCTP [RFC3758] specification [RFC3758] when using
partial reliability to transmit IPFIX Messages containing only
Data Sets.

However, Exporting Processes SHOULD mark such IPFIX Messages for
retransmission for as long as resource or other constraints allow.

10.3. UDP

This section describes how IPFIX is transported over UDP [UDP].

10.3.1. Congestion Avoidance

UDP has no integral congestion-avoidance mechanism. Its use over
congestion-sensitive network paths is therefore not recommended. UDP
MAY be used in deployments where Exporters and Collectors always
communicate over dedicated links that are not susceptible to
congestion, i.e., links that are over-provisioned compared to the
maximum export rate from the Exporters.

10.3.2. Reliability

UDP is not a reliable transport protocol, protocol and cannot guarantee
delivery of messages. IPFIX Messages sent from the Exporting Process
to the Collecting Process using UDP may therefore be lost. UDP MUST
NOT be used unless the application can tolerate some loss of IPFIX
Messages.

The Collecting Process SHOULD deduce the loss and reordering of IPFIX
Data Records by looking at the discontinuities in the IPFIX Sequence
Number. In the case of UDP, the IPFIX Sequence Number contains the
total number of IPFIX Data Records sent for the UDP Transport Session
prior to the receipt of this IPFIX Message, modulo 2^32. A Collector
SHOULD detect out-of-sequence, dropped, or duplicate IPFIX Messages
by tracking the Sequence Number.

Exporting Processes exporting IPFIX Messages via UDP MUST include a
valid UDP checksum [UDP] in UDP datagrams including IPFIX messages. Messages.

10.3.3. MTU

The maximum size of exported messages MUST be configured such that
the total packet size does not exceed the path MTU. PMTU. If the path MTU PMTU is
unknown, a maximum packet size of 512 octets SHOULD be used.

10.3.4. Session Establishment and Shutdown

As UDP is a connectionless protocol, there is no real session
establishment or shutdown for IPFIX over UDP. An Exporting Process
starts sending IPFIX Messages to a Collecting Process at one point in
time,
time and stops sending them at another point in time. This can lead
to some complications in Template management, which are as outlined in
Section 8.4 above.

10.3.5. Failover and Session Duplication

Because UDP is not a connection-oriented protocol, the Exporting
Process is unable to determine from the transport protocol that the
Collecting Process is no longer able to receive the IPFIX Messages.
Therefore, it cannot invoke a failover mechanism. However, the
Exporting Process MAY duplicate the IPFIX Message to several
Collecting Processes.

10.4. TCP

This section describes how IPFIX is transported over TCP [TCP].

10.4.1. Congestion Avoidance

TCP controls the rate at which data can be sent from the Exporting
Process to the Collecting Process, using a mechanism that takes into
account both congestion in the network and the capabilities of the
receiver.

Therefore, an IPFIX Exporting Process may not be able to send IPFIX
Messages at the rate that the Metering Process generates them, either
because of congestion in the network or because the Collecting
Process cannot handle IPFIX Messages fast enough. As long as
congestion is transient, the Exporting Process can buffer IPFIX
Messages for transmission. But such buffering is necessarily
limited, both because of resource limitations and because of
timeliness requirements, so ongoing and/or severe congestion may lead
to a situation where the Exporting Process is blocked.

When an Exporting Process has Data Records to export but the
transmission buffer is full, and it wants to avoid blocking, it can
decide to drop some Data Records. The dropped Data Records MUST be
accounted for, so that the number of lost records can later be
reported as described in Section 4.3.

10.4.2. Reliability

TCP ensures reliable delivery of data from the Exporting Process to
the Collecting Process.

10.4.3. MTU

As TCP offers a stream service instead of a datagram or sequential
packet service, IPFIX Messages transported over TCP are instead
separated using the Length field in the IPFIX Message Header. The
Exporting Process can choose any valid length for exported IPFIX
Messages, as TCP handles segmentation.

Exporting Processes may choose IPFIX Message lengths lower than the
maximum in order to ensure timely export of Data Records.

10.4.4. Connection Establishment and Shutdown

The IPFIX Exporting Process initiates a TCP connection to the
Collecting Process. An Exporting Process MAY support more than one
active connection to different Collecting Processes (including the
case of different Collecting Processes on the same host). An
Exporting Process MAY support more than one active connection to the
same Collecting Process to avoid head of line head-of-line blocking across
Observation Domains.

The Exporter MAY log an alarm if the underlying TCP connection
establishment times out; this timeout should be configurable on the
Exporter.

When an Exporting Process is shut down, it SHOULD shut down the TCP
connection.

When a Collecting Process no longer wants to receive IPFIX Messages,
it SHOULD close its end of the connection. The Collecting Process
SHOULD continue to read IPFIX Messages until the Exporting Process
has closed its end.

When a Collecting Process detects that the TCP connection to the
Exporting Process has terminated abnormally, it MUST continue to
listen for a new connection.

When an Exporting Process detects that the TCP connection to the
Collecting Process has terminated abnormally, it SHOULD try to
re-establish the connection. Connection timeouts and retry schedules
SHOULD be configurable. In the default configuration, an Exporting
Process MUST NOT attempt to establish a connection more frequently
than once per minute.

10.4.5. Failover

If the Collecting Process does not acknowledge an attempt by the
Exporting Process to establish a connection, TCP will automatically
retry connection establishment using exponential backoff. The
Exporter MAY log an alarm if the underlying TCP connection
establishment times out; this timeout should be configurable on the
Exporter.

The Exporting Process MAY open a backup TCP connection to a
Collecting Process in advance, if it supports Collecting Process
failover.

11. Security Considerations

The security considerations for the IPFIX protocol have been derived
from an analysis of potential security threats, as discussed in the
"Security Considerations"
Security Considerations section of the IPFIX requirements document
[RFC3917]. The requirements for IPFIX security are as follows:

1. IPFIX must provide a mechanism to ensure the confidentiality of
IPFIX data transferred from an Exporting Process to a Collecting
Process, in order to prevent disclosure of Flow Records
transported via IPFIX.

2. IPFIX must provide a mechanism to ensure the integrity of IPFIX
data transferred from an Exporting Process to a Collecting
Process, in order to prevent the injection of incorrect data or
control information (e.g., Templates), or the duplication of
Messages, in an IPFIX Message stream.

3. IPFIX must provide a mechanism to authenticate IPFIX Collecting
and Exporting Processes, to prevent the collection of data from an
unauthorized Exporting Process or the export of data to an
unauthorized Collecting Process.

Because IPFIX can be used to collect information for network
forensics and billing purposes, attacks designed to confuse, disable,
or take information from an IPFIX collection system may be seen as a
prime objective during a sophisticated network attack.

An attacker in a position to inject false messages into an IPFIX
Message stream can either affect either the application using IPFIX (by
falsifying data), data) or the IPFIX Collecting Process itself (by modifying
or revoking Templates, or changing options); for this reason, IPFIX
Message integrity is important.

The IPFIX Messages themselves may also contain information of value
to an attacker, including information about the configuration of the
network as well as end-user traffic and payload data, so care must be
taken to confine their visibility to authorized users. When an
Information Element containing end-user payload information is
exported, it SHOULD be transmitted to the Collecting Process using a
means that secures its contents against eavesdropping. Suitable
mechanisms include the use of either a direct point-to-point
connection assumed to be unavailable to attackers, or the use of an
encryption mechanism. It is the responsibility of the Collecting
Process to provide a satisfactory degree of security for this
collected data, including, if necessary, encryption and/or
anonymization of any reported data; see Section 11.8.

11.1. Applicability of TLS and DTLS

Transport Layer Security (TLS) [RFC5246] and Datagram Transport Layer
Security (DTLS) [RFC6347] were designed to provide the
confidentiality, integrity, and authentication assurances required by
the IPFIX protocol, without the need for pre-shared keys.

IPFIX Exporting Processes and Collecting Processes using TCP MUST
support TLS version 1.1 and SHOULD support TLS version 1.2 [RFC5246],
including the mandatory cipher suite(s) ciphersuite(s) specified in each version.
IPFIX Exporting Processes and Collecting Processes using UDP or SCTP
MUST support DTLS version 1.0 and SHOULD support DTLS version 1.2
[RFC6347], including the mandatory cipher suite(s) ciphersuite(s) specified in each
version.

Note that DTLS is selected as the security mechanism for SCTP.
Though TLS bindings to SCTP are defined in [RFC3436], they require
that all communication to be over reliable, bidirectional streams, and
they also require one TLS connection per stream. This arrangement is
not compatible with the rationale behind the choice of SCTP as an
IPFIX transport protocol.

Note that using DTLS has a man-in-the-middle vulnerability not
present in TLS, allowing a message to be removed from the stream
without the knowledge of either the sender or receiver.
Additionally, when using DTLS over SCTP, an attacker could inject
SCTP control information and shut down the SCTP association, causing
a loss of IPFIX Messages if those messages are buffered outside of
the SCTP association. Techniques such as those described in
[RFC6083] could be used to overcome these vulnerabilities.

When using DTLS over SCTP, the Exporting Process MUST ensure that
each IPFIX Message is sent over the same SCTP stream Stream that would be
used when sending the same IPFIX Message directly over SCTP. Note
that DTLS may send its own control messages on stream 0 with full
reliability; however, this will not interfere with the processing of
stream 0 IPFIX Messages at the Collecting Process, because DTLS
consumes its own control messages before passing IPFIX Messages up to
the application layer.

When using DTLS over SCTP or UDP, the Heartbeat Extension [RFC6520]
SHOULD be used, especially on long-lived Transport Sessions, to
ensure that the association remains active.

Exporting and Collecting Processes MUST NOT request, offer, or use
any version of SSL, the Secure Socket Layer (SSL), or any version of TLS
prior to 1.1, due to known security vulnerabilities in prior versions
of the protocol; TLS; see Appendix E of [RFC5246] for more information.

11.2. Usage

The IPFIX Exporting Process initiates the communication to the IPFIX
Collecting Process, Process and acts as a TLS or DTLS client according to
[RFC5246] and [RFC6347] [RFC6347], while the IPFIX Collecting Process acts as a
TLS or DTLS server. The DTLS client opens a secure connection on the
SCTP port 4740 of the DTLS server if SCTP is selected as the
transport protocol. The TLS client opens a secure connection on the TCP
port 4740 of the TLS server if TCP is selected as the transport
protocol. The DTLS client opens a secure connection on the UDP port 4740
of the DTLS server if UDP is selected as the transport protocol.

11.3. Mutual Authentication

When using TLS or DTLS, IPFIX Exporting Processes and IPFIX
Collecting Processes SHOULD be identified by a certificate containing
the DNS-ID identifier as discussed in Section 6.4 of [RFC6125]; the inclusion of
Common Names (CN-IDs) in certificates identifying IPFIX Exporting
Processes or Collecting Processes is NOT RECOMMENDED.

To prevent man-in-the-middle attacks from impostor Exporting or
Collecting Processes, the acceptance of data from an unauthorized
Exporting Process, or the export of data to an unauthorized
Collecting Process, mutual authentication MUST be used for both TLS
and DTLS. Exporting Processes MUST verify the reference identifiers
of the Collecting Processes to which they are exporting IPFIX messages to
Messages against those stored in the certificates. Likewise,
Collecting Processes MUST verify the reference identifiers of the
Exporting Processes from which they are receiving IPFIX Messages from
against those stored in the certificates. Exporting Processes MUST
NOT export to non-
verified non-verified Collecting Processes, and Collecting
Processes MUST NOT accept IPFIX Messages from non-verified Exporting
Processes.

Exporting Processes and Collecting Processes MUST support the
verification of certificates against an explicitly authorized list of
peer certificates identified by Common Name, Name and SHOULD support the
verification of reference identifiers by matching the DNS-ID or CN-ID
with a DNS lookup of the peer.

IPFIX Exporting Processes and Collecting Processes MUST use non-NULL
ciphersuites for authentication, integrity, and confidentiality.

11.4. Protection against DoS Attacks

An attacker may mount a denial-of-service (DoS) attack against an
IPFIX collection system either directly, by sending large amounts of
traffic to a Collecting Process, or indirectly, by generating large
amounts of traffic to be measured by a Metering Process.

Direct DoS attacks can also involve state exhaustion, whether at the
transport layer (e.g., by creating a large number of pending
connections),
connections) or within the IPFIX Collecting Process itself (e.g., by
sending Flow Records pending Template or scope information, or a
large amount of Options Template Records, etc.).

SCTP mandates a cookie-exchange mechanism designed to defend against
SCTP state exhaustion DoS attacks. Similarly, TCP provides the "SYN
cookie" mechanism to mitigate state exhaustion; SYN cookies SHOULD be
used by any Collecting Process accepting TCP connections. DTLS also
provides cookie exchange to protect against DTLS server state
exhaustion.

The reader should note that there is no way to prevent fake IPFIX
Message processing (and state creation) for UDP & and SCTP
communication. The use of TLS and DTLS can obviously prevent the
creation of fake states, but they are themselves prone to state
exhaustion attacks. Therefore, Collector rate limiting SHOULD be
used to protect TLS & and DTLS (like limiting the number of new TLS or
DTLS session sessions per second to a sensible number).

IPFIX state exhaustion attacks can be mitigated by limiting the rate
at which new connections or associations will be opened by the
Collecting Process, Process; limiting the rate at which IPFIX Messages will be
accepted by the Collecting Process, Process; and adaptively limiting the
amount of state kept, particularly for records waiting on for Templates.
These rate and state limits MAY be provided by a Collecting Process,
and if provided, the limits SHOULD be user configurable.

Additionally, an IPFIX Collecting Process can eliminate the risk of
state exhaustion attacks from untrusted nodes by requiring TLS or
DTLS mutual authentication, causing the Collecting Process to accept
IPFIX Messages only from trusted sources.

With respect to indirect denial of service, the behavior of IPFIX
under overload conditions depends on the transport protocol in use.
For IPFIX over TCP, TCP congestion control would cause the flow of
IPFIX Messages to back off and eventually stall, blinding the IPFIX
system. SCTP improves upon this situation somewhat, as some IPFIX
Messages would continue to be received by the Collecting Process due
to the avoidance of head-of-line blocking by SCTP's multiple streams
and partial reliability features, possibly affording some visibility
of the attack. The situation is similar with UDP, as some datagrams
may continue to be received at the Collecting Process, effectively
applying sampling to the IPFIX Message stream, stream and implying that some
forensics may
information about the attack will be left. available.

To minimize IPFIX Message loss under overload conditions, some
mechanism for service differentiation could be used to prioritize
IPFIX traffic over other traffic on the same link. Alternatively,
IPFIX Messages can be transported over a dedicated network. In this
case, care must be taken to ensure that the dedicated network can
handle the expected peak IPFIX Message traffic.

11.5. When DTLS or TLS Is Not an Option

The use of DTLS or TLS might not be possible in some cases cases, due to
performance issues or other operational concerns.

Without TLS or DTLS mutual authentication, IPFIX Exporting Processes
and Collecting Processes can fall back on using IP source addresses
to authenticate their peers. A policy of allocating Exporting
Process and Collecting Process IP addresses from specified address
ranges, and using ingress filtering to prevent spoofing, can improve
the usefulness of this approach. Again, completely segregating IPFIX
traffic on a dedicated network, where possible, can improve security
even further. In any case, the use of open Collecting Processes
(those that will accept IPFIX Messages from any Exporting Process
regardless of IP address or identity) is discouraged.

Modern TCP and SCTP implementations are resistant to blind insertion
attacks (see [RFC4960], [RFC4960] and [RFC6528]); however, UDP offers no such
protection. For this reason, IPFIX Message traffic transported via
UDP and not secured via DTLS SHOULD be protected via segregation to a
dedicated network.

11.6. Logging an IPFIX Attack

IPFIX Collecting Processes MUST detect potential IPFIX Message
insertion or loss conditions by tracking the IPFIX Sequence Number, Number
and SHOULD provide a logging mechanism for reporting out-of-sequence
messages. Note that an attacker may be able to exploit the handling
of out-of-sequence messages at the Collecting Process, so care should
be taken in handling these conditions. For example, a Collecting
Process that simply resets the expected Sequence Number upon receipt
of a later Sequence Number could be temporarily blinded by deliberate
injection of later Sequence Numbers.

IPFIX Exporting and Collecting Processes SHOULD log any connection
attempt that fails due to authentication failure, whether due to
being presented an unauthorized or mismatched certificate during TLS
or DTLS mutual authentication, or due to a connection attempt from an
unauthorized IP address when TLS or DTLS is not in use.

IPFIX Exporting and Collecting Processes SHOULD detect and log any
SCTP association reset or TCP connection reset.

11.7. Securing the Collector

The security of the Collector and its implementation is important to
achieve overall security; however, a complete set of security
guidelines for Collector implementation is outside the scope of this
document.

As IPFIX uses length-prefix encodings, Collector implementors should
take care to ensure the detection of and proper operation despite inconsistent values that could
impact IPFIX Message decoding. decoding, and proper operation in the presence
of such inconsistent values.

Specifically, IPFIX Message, Set, and variable-length Information
Element lengths must be checked for consistency to avoid buffer-
sizing vulnerabilities.

Collector implementors should also pay special attention to UTF-8
encoding of string datatypes, data types, as vulnerabilities may exist in the
interpretation of ill-formed UTF-8 values; see Section 6.1.6.

11.8. Privacy Considerations for Collected Data

Flow data exported by Exporting Processes, Processes and collected by Collecting Processes,
Processes typically contains information about traffic on the
observed network. This information may be personally identifiable
and privacy-sensitive. The storage of this data must be protected
via technical as well as policy means to ensure that the privacy of
the users of the measured network is protected. A complete
specification of such means is out of scope for this document, document and is
specific to the application and storage technology used.

12. Management Considerations

[RFC6615] specifies a MIB module that defines managed objects for
monitoring IPFIX Devices, including basic configuration. This MIB
can be used to measure the impact of IPFIX export on the monitoring
network, and
network; it contains tables covering:

Transport Session,
Cache definition,
Observation Point definition,
Template and Options Template definition,
export features (failover, load-balancing, duplicate), and
export statistics per Process, Session, and Template

From an operational aspect, an important function of this MIB module
is given provided by the Transport Session Statistical table table, which
contains the rate (in bytes per second) at which the Collector
receives or the Exporter sends out IPFIX Messages. Of particular
interest to operations, the Transport Session Statistical table in
Section 5.8.1 of this MIB module (Section 5.8.1) exposes the rate of collection or
export of IPFIX Messages, which allows the measurement of the
bandwidth used by IPFIX export.

RFC6727

[RFC6727] describes extensions to the IPFIX-SELECTOR-MIB module, module
specified in RFC6615, containing [RFC6615] and contains managed objects for providing
information on applied packet selection functions and their
parameters (filtering and sampling).

Since the two MIB IPFIX-SELECTOR-MIB [RFC6615] and PSAMP-MIB [RFC6727]
modules [RFC6615][RFC6727] only contain read-only objects, they cannot be used for
configuration of IPFIX Devices. [RFC6728] specifies a configuration
data model for the IPFIX and PSAMP protocols protocols, using the Network
Configuration Protocol (NETCONF). This data model covers Selection
Processes, Caches, Exporting Processes, and Collecting Processes on
IPFIX and PSAMP Devices, and is defined using UML (Unified Modeling
Language) class diagrams and formally specified using YANG. The
configuration data is encoded in Extensible Markup Language (XML).

A few mechanisms specified alongside the IPFIX Protocol protocol can help
monitor and reduce bandwidth used for IPFIX Export:

- a bandwidth-saving method for exporting redundant information in
IPFIX [RFC5473]

- an efficient method for exporting bidirectional flows [RFC5103]

- a method for the definition and export of complex data structures
[RFC6313]

Alternately,
Alternatively, PSAMP [RFC5474] can be used to export packets sampled
by statistical and other methods, which may be applicable to many
monitoring areas for which IPFIX is also suited, and suited. PSAMP also provides
control over the impact on the measured network through its sampling
rate. The set of packet selection techniques (Sampling, Filtering,
and hashing) standardized by PSAMP is described in [RFC5475]. PSAMP
also defines an explicitly configurable export rate limit in section
Section 8.4 of [RFC5474].

13. IANA Considerations

On publication of this document,

IANA will update has updated the IPFIX "IPFIX Information Element Registry [IPFIX-IANA] to update Elements" registry
[IANA-IPFIX] so that all references that previously pointed to
RFC5101 to
RFC 5101 now point to this document, instead.

This document has no further actions for IANA; the text below is
explanatory. instead.

IPFIX Messages use two fields with assigned values. These are the
IPFIX Version Number, indicating which version of the IPFIX Protocol protocol
was used to export an IPFIX Message, and the IPFIX Set ID, indicating
the type for each set of information within an IPFIX Message.

The Information Elements used by IPFIX, and sub-registries of
Information Element values, are managed by IANA [IPFIX-IANA], [IANA-IPFIX], as are
the Private Enterprise Numbers used by enterprise-specific
Information Elements [PEN-IANA]. [IANA-PEN]. This document makes no changes to
these registries.

The IPFIX Version Number value of 0x000a (10) is reserved for the
IPFIX protocol specified in this document. Set ID values of 0 and 1
are not used, for historical reasons [RFC3954]. The Set ID value of
2 is reserved for the Template Set. The Set ID value of 3 is
reserved for the Options Template Set. All other Set ID values from
4 to 255 are reserved for future use. Set ID values above 255 are
used for Data Sets.

New assignments in either IPFIX the "IPFIX Version Number Number" or IPFIX "IPFIX Set ID
assignments
IDs" sub-registries require a Standards Action [RFC5226], i.e., they
are to be made via Standards Track RFCs approved by the IESG.

Appendix A. IPFIX Encoding Examples

This appendix, which is a not a normative reference, contains IPFIX
encoding examples.

Let's consider the example of an IPFIX Message composed of a Template
Set, a Data Set (which contains three Data Records), an Options
Template Set Set, and a another Data Set (which contains 2 two Data Records
related to the previous Options Template Record).

IPFIX Message:

+--------+------------------------------------------. . .
| | +--------------+ +------------------+
|Message | | Template | | Data |
| Header | | Set | | Set | . . .
| | | (1 Template) | | (3 Data Records) |
| | +--------------+ +------------------+
+--------+------------------------------------------. . .

. . .-------------------------------------------+
+------------------+ +------------------+ |
| Options | | Data | |
. . . | Template Set | | Set | |
| (1 Template) | | (2 Data Records) | |
+------------------+ +------------------+ |
. . .-------------------------------------------+

A.1. Message Header Example

The Message Header is composed of:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version = 0x000a | Length = 152 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Export Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Observation Domain ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.2. Template Set Examples

A.2.1. Template Set Using IANA Information Elements

We want to report the following Information Elements:

- The IPv4 source IP address: sourceIPv4Address in [IPFIX-IANA], [IANA-IPFIX], with a
length of 4 octets

- The IPv4 destination IP address: destinationIPv4Address in
[IPFIX-IANA], [IANA-IPFIX],
with a length of 4 octets

- The next-hop Next-hop IP address (IPv4): ipNextHopIPv4Address in
[IPFIX-IANA], [IANA-IPFIX], with
a length of 4 octets

- The number Number of packets of the Flow: packetDeltaCount in
[IPFIX-IANA], [IANA-IPFIX], with
a length of 4 octets

- The number Number of octets of the Flow: octetDeltaCount in
[IPFIX-IANA], [IANA-IPFIX], with a
length of 4 octets

Therefore, the Template Set will be composed of the following:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 2 | Length = 28 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 256 | Field Count = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| sourceIPv4Address = 8 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| destinationIPv4Address = 12 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| ipNextHopIPv4Address = 15 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| packetDeltaCount = 2 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| octetDeltaCount = 1 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.2.2. Template Set Using Enterprise-Specific Information Elements

We want to report the following Information Elements:

- The IPv4 source IP address: sourceIPv4Address in [IPFIX-IANA], [IANA-IPFIX], with a
length of 4 octets

- The IPv4 destination IP address: destinationIPv4Address in [IPFIX-
IANA], [IANA-IPFIX],
with a length of 4 octets

- An enterprise-specific Information Element representing proprietary
information, with a type of 15 and a length of 4 octets

- The number Number of packets of the Flow: packetDeltaCount in [IPFIX-
IANA], [IANA-IPFIX], with
a length of 4 octets

- The number Number of octets of the Flow: octetDeltaCount in [IPFIX-IANA], [IANA-IPFIX], with a
length of 4 octets

Therefore, the Template Set will be composed of the following:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 2 | Length = 32 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 257 | Field Count = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| sourceIPv4Address = 8 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| destinationIPv4Address = 12 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Information Element Id. id. = 15| Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| packetDeltaCount = 2 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| octetDeltaCount = 1 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.3. Data Set Example

In this example, we report the following three Flow Records:

Src IP addr. Addr. | Dst IP addr. Addr. | Next Hop addr. Next-Hop Addr. | Packet | Octets
| | | Number | Number
------------------------------------------------------------------
----------------------------------------------------------------
192.0.2.12 | 192.0.2.254 | 192.0.2.1 | 5009 | 5344385
192.0.2.27 | 192.0.2.23 | 192.0.2.2 | 748 | 388934
192.0.2.56 | 192.0.2.65 | 192.0.2.3 | 5 | 6534

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 256 | Length = 64 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.254 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5009 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5344385 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.27 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.23 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 748 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 388934 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.56 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.65 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.0.2.3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 6534 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Note that padding is not necessary in this example.

A.4. Options Template Set Examples

A.4.1. Options Template Set Using IANA Information Elements

Per line card (the router being composed of two line cards), we want
to report the following Information Elements:

- Total number of IPFIX Messages: exportedMessageTotalCount [IPFIX-
IANA],
[IANA-IPFIX], with a length of 2 octets

- Total number of exported Flows: exportedFlowRecordTotalCount
[IPFIX-IANA],
[IANA-IPFIX], with a length of 2 octets

The line card, which is represented by the lineCardId Information
Element [IPFIX-IANA], [IANA-IPFIX], is used as the Scope Field.

Therefore, the Options Template Set will be:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length = 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 258 | Field Count = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field Count = 1 |0| lineCardId = 141 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 |0|exportedMessageTotalCount=41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |0|exportedFlowRecordTotalCo.=42|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.4.2. Options Template Set Using Enterprise-Specific Information
Elements

Per line card (the router being composed of two line cards), we want
to report the following Information Elements:

- Total number of IPFIX Messages: exportedMessageTotalCount
[IPFIX-IANA],
[IANA-IPFIX], with a length of 2 octets

- An enterprise-specific number of exported Flows, with a type of 42
and a length of 4 octets

The line card, which is represented by the lineCardId Information
Element [IPFIX-IANA], [IANA-IPFIX], is used as the Scope Field.

The format of the Options Template Set is as follows:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length = 28 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 259 | Field Count = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field Count = 1 |0| lineCardId = 141 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 |0|exportedFlowRecordTotalCo.=41| |0|exportedMessageTotalCount=41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |1|Information Element Id. id. = 42 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 | Enterprise number ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Enterprise number | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.4.3. Options Template Set Using an Enterprise-Specific Scope

In this example, we want to export the same information as in the
example in Section Appendix A.4.1:

- Total number of IPFIX Messages: exportedMessageTotalCount
[IPFIX-IANA],
[IANA-IPFIX], with a length of 2 octets

- Total number of exported Flows: exportedFlowRecordTotalCount
[IPFIX-IANA],
[IANA-IPFIX], with a length of 2 octets

But this time, the information pertains to a proprietary scope,
identified by enterprise-specific Information Element number 123.

The format of the Options Template Set is now as follows:

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length = 28 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 260 | Field Count = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field Count = 1 |1|Scope 1 Infor. El. Id. id. = 123 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 | Enterprise Number ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Enterprise Number |0|exportedMessageTotalCount=41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |0|exportedFlowRecordTotalCo.=42|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.4.4. Data Set Using an Enterprise-Specific Scope

In this example, we report the following two Data Records:

Enterprise field 123 | IPFIX Message | Exported Flow Records
-------------------------------------------------------------------
---------------------------------------------------------------
1 | 345 | 10201
2 | 690 | 20402

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 260 | Length = 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 345 | 10201 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 690 | 20402 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.5. Variable-Length Information Element Examples

A.5.1. Example of Variable-Length Information Element with Length
Inferior to
Less Than 255 Octets

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5 | 5 octet 5-octet Information Element |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.5.2. Example of Variable-Length Information Element with 3 Octet 3-Octet
Length Encoding

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | 1000 | IE ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1000 octet 1000-octet Information Element |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... IE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

References

Normative References

[IANA-IPFIX]
IANA, "IP Flow Information Export (IPFIX) Entities",
<http://www.iana.org/assignments/ipfix/>.

[RFC1014] Sun Microsystems, Inc., "XDR: External Data Representation
Standard", RFC 1014, June 1987.

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

[RFC3436] Jungmaier, A., Rescorla, E., and M. Tuexen, "Transport
Layer Security over Stream Control Transmission Protocol",
RFC 3436, December 2002.

[RFC3629] Yergeau, F., "UTF-8, a transformation format of
ISO 10646", STD 63, RFC 3629, November 2003.

[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758, May 2004.

[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, September 2007.

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

[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.

[RFC5905] Mills, D., Delaware, U., Martin, J., Ed., Burbank, J. J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010 2010.

[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, March 2011.

[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012.

[RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, M., "Transport
Layer Security (TLS) and Datagram Transport Layer Security
(DTLS) Heartbeat Extension", RFC 6520, February 2012.

[RFC7012] Claise, B., Ed., and B. Trammell, Ed., "Information Model
for IP Flow Information Export (IPFIX)", RFC 7012,
September 2013.

[TCP] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, September 1981.

[UDP] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.

[RFC5102bis]

Informative References

[IEEE.754.2008]
Institute of Electrical and Electronics Engineers, "IEEE
Standard for Floating-Point Arithmetic", IEEE
Standard 754, August 2008.

[IPFIX-MED-PROTO]
Claise, B., Kobayashi, A., and B. Trammell, eds., "Information Model
for "Operation of
the IP Flow Information Export", draft-ietf-ipfix-
information-model-rfc5102bis-10.txt, Export (IPFIX) Protocol on IPFIX
Mediators", Work in Progress,
February July 2013.

[IPFIX-IANA] http://www.iana.org/assignments/ipfix/ipfix.xml

Informative References

[IANA-PEN]
IANA, "Private Enterprise Numbers",
<http://www.iana.org/assignments/enterprise-numbers/>.

[POSIX.1] IEEE 1003.1-2008, "IEEE Standard for Information
Technology - Portable Operating System Interface
(POSIX(R))", 2008.

[RFC2579] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Textual Conventions for SMIv2",
STD 58, RFC 2579, April 1999.

[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.

[RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander,
"Requirements for IP Flow Information Export (IPFIX)",
RFC 3917, October 2004.

[RFC3954] Claise, B., Ed., "Cisco Systems NetFlow Services Export
Version 9", RFC 3954, October 2004.

[RFC5101] Claise, B., Ed., "Bidirectional Flow Export Using IP
Flow Information Export (IPFIX)", RFC 5103, January
2008.

[RFC5103] Trammell, B., and E. Boschi, "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", RFC 5101, January 2008.

[RFC5103] Trammell, B. and E. Boschi, "Bidirectional Flow Export
Using IP Flow Information Export (IPFIX)", RFC 5103,
January 2008.

[RFC5153] Boschi, E., Mark, L., Quittek Quittek, J., Stiemerling, M., and P.
Aitken, "IP Flow Information Export (IPFIX) Implementation
Guidelines", RFC5153, RFC 5153, April 2008 2008.

[RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
"Architecture for IP Flow Information
Export", RFC5470, Export", RFC 5470,
March 2009.

[RFC5471] Schmoll, C., Aitken, P., and B. Claise, "Guidelines for IP
Flow Information Export (IPFIX) Testing", RFC 5471,
March 2009.

[RFC5472] Zseby, T., Boschi, E., Brownlee, N., and B. Claise, "IP
Flow Information Export (IPFIX) Applicability",
RFC5472, March 2009.

[RFC5471] Schmoll, C., Aitken, P., and B. Claise, "Guidelines
for IP Flow Information Export (IPFIX) Testing",
RFC5471, RFC 5472,
March 2009.

[RFC5473] Boschi, E., Mark, L., and B. Claise, "Reducing Redundancy
in IP Flow Information Export (IPFIX) and Packet Sampling
(PSAMP) Reports", RFC5473, RFC 5473, March 2009.

[RFC5474] Duffield, N., Ed., Chiou, D., Claise, B., Greenberg, A.,
Grossglauser, M., and J. Rexford, "A Framework for Packet
Selection and Reporting", RFC 5474, March 2009.

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

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

[RFC5477] Dietz, T., Claise, B., Aitken, P., Dressler, F., and G.
Carle, "Information Model for Packet Sampling Exports",
RFC 5477, March 2009.

[RFC5610] Boschi, E., Trammell, B., Mark, L., and T. Zseby,
"Exporting Type Information for IP Flow Information Export
(IPFIX) Information Elements", RFC 5610, July 2009.

[RFC5655] Trammell, B., Boschi, E., Mark, L., Zseby, T., and A.
Wagner, "Specification of the IP Flow Information Export
(IPFIX) File Format", RFC 5655, October 2009.

[RFC6083] Tuexen, M., Seggelman, R. Seggelmann, R., and E. Rescola, Rescorla, "Datagram
Transport Layer Security (DTLS) for Stream Control
Transmission Protocol (SCTP)", RFC6083, RFC 6083, January 2011.

[RFC6183] Kobayashi, A., Claise, B., Muenz, G., and K. Ishibashi,
"IP Flow Information Export (IPFIX) Mediation: Framework",
RFC 6183, April 2011.

[RFC6313] Claise, B., Dhandapani, G., Aitken, P, P., and S. Yates,
"Export of Structured Data in IP Flow Information Export
(IPFIX)", RFC6313, RFC 6313, July 2011.

[RFC6183] Kobayashi, A., Claise, B., Muenz, G, and K. Ishibashi,
"IP Flow Information Export (IPFIX) Mediation:
Framework", RFC6183, April 2011.

[RFC6526] Claise, B., Aitken, P., Johnson, A. A., and G. Muenz,
"IPFIX "IP
Flow Information Export per SCTP (IPFIX) Per Stream Control
Transmission Protocol (SCTP) Stream", RFC 6526,
March 2012.

[RFC6528] Gont, F. and S. Bellovin, "Defending Against against Sequence
Number Attacks", RFC 6528, February 2012.

[RFC6615] Dietz, T., Ed., Kobayashi, A., Claise, B., and G. Muenz,
"Definitions of Managed Objects for IP Flow Information
Export", RFC 6615, June 2012.

[RFC6727] Dietz, T. T., Ed., Claise, B., and J. Quittek, "Definitions
of Managed Objects for Packet Sampling", RFC 6727,
October 2012.

[RFC6728] Muenz, G., Claise, B., and P. Aitken, "Configuration Data
Model for IPFIX the IP Flow Information Export (IPFIX) and PSAMP",
Packet Sampling (PSAMP) Protocols", RFC 6728,
October 2012.

[PEN-IANA] IANA Private Enterprise Numbers registry
http://www.iana.org/assignments/enterprise-numbers.

[POSIX.1] IEEE 1003.1-2008 - IEEE Standard for Information
Technology - Portable Operating System Interface,
IEEE, 2008.

[IEEE.754.1985] Institute of Electrical and Electronics Engineers,
"Standard for Binary Floating-Point Arithmetic", IEEE
Standard 754, August 1985.

[UTF8-EXPLOIT]
Davis, M. and M. Suignard, "Unicode Technical Report #36:
Unicode Security Considerations", The Unicode Consortium,
July 2012.

[IPFIX-MED-PROTO] Claise, B., Kobayashi, A., and B. Trammell,
"Specification of the Protocol for IPFIX Mediations",
draft-ietf-ipfix-mediation-protocol-05, Work in
Progress, June 2013.

Acknowledgments

We would like to thank Ganesh Sadasivan, as well, Sadasivan for his significant
contribution during the initial phases of the protocol specification.
Additional thanks go to Juergen Quittek for coordination between
IPFIX and PSAMP; Nevil Brownlee, Dave Plonka, and Andrew Johnson for
the thorough reviews; Randall Stewart and Peter Lei for their SCTP
expertise and contributions; Martin Djernaes for the first essay on
the SCTP section; Michael Behringer and Eric Vyncke for their advice
and knowledge in security; Michael Tuexen for his help regarding the
DTLS section; Elisa Boschi for her contribution regarding the
improvement of SCTP sections; Mark Fullmer, Sebastian Zander, Jeff
Meyer, Maurizio Molina, Carter Bullard, Tal Givoly, Lutz Mark, David
Moore, Robert Lowe, Paul Calato, Andrew Feren, Gerhard Muenz, Sue
Hares, and many more, for the technical reviews and feedback.
Finally, a special mention to Adrian Farrel for his attention to
management and operational aspects.

Contributors

Stewart Bryant
Cisco Systems
10 New Square, Bedfont Lakes
Feltham, Middlesex TW18 8HA
United Kingdom

EMail: stbryant@cisco.com

Simon Leinen
SWITCH
Werdstrasse 2
P.O. Box 8021
Zurich
Switzerland

Phone: +41 44 268 1536
EMail: simon.leinen@switch.ch

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

Phone: +49 6221 4342-128
EMail: Thomas.Dietz@nw.neclab.eu

Authors' Addresses

Benoit Claise (Ed.) (editor)
Cisco Systems, Inc.
De Kleetlaan 6a b1
1831 Diegem
Belgium

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

Brian Trammell (Ed.) (editor)
Swiss Federal Institute of Technology Zurich
Gloriastrasse 35
8092 Zurich
Switzerland

Phone: +41 44 632 70 13
EMail: trammell@tik.ee.ethz.ch

Paul Aitken
Cisco Systems, Inc.
96 Commercial Quay
Commercial Street, Edinburgh EH6 6LX
United Kingdom

Phone: +44 131 561 3616
Email: paitken@cisco.com

Contributors' Addresses

Stewart Bryant
Cisco Systems, Inc.
250, Longwater,
Green Park,
Reading, RG2 6GB,
United Kingdom

Phone: +44 (0)20 8824-8828
EMail: stbryant@cisco.com

Simon Leinen
SWITCH
Werdstrasse 2
P.O. Box
8021 Zurich
Switzerland

Phone: +41 44 268 1536
EMail: simon.leinen@switch.ch

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

Phone: +49 6221 4342-128
EMail: Thomas.Dietz@nw.neclab.eu paitken@cisco.com