| Rfc | 5101 |
|---|
| Title | Specification of the IP Flow Information Export (IPFIX) Protocol for
the Exchange of IP Traffic Flow Information |
|---|
| Author | B. Claise, Ed. |
|---|
| Date | January
2008 |
|---|
| Format: | TXT, HTML |
|---|
| Obsoleted by | RFC7011 |
|---|
| Status: | PROPOSED
STANDARD |
|---|
|
Network Working Group B. Claise, Ed.
Request for Comments: 5101 Cisco Systems, Inc.
Category: Standards Track January 2008
Specification of the IP Flow Information Export (IPFIX) Protocol
for the Exchange of IP Traffic Flow Information
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
This document specifies the IP Flow Information Export (IPFIX)
protocol that serves for transmitting IP Traffic Flow information
over the network. In order to transmit IP Traffic Flow information
from an Exporting Process to an information Collecting Process, a
common representation of flow data and a standard means of
communicating them is 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.
Table of Contents
1. Introduction ....................................................3
1.1. IPFIX Documents Overview ...................................4
2. Terminology .....................................................4
2.1. Terminology Summary Table ..................................9
3. IPFIX Message Format ...........................................10
3.1. Message Header Format .....................................11
3.2. Field Specifier Format ....................................13
3.3. Set and Set Header Format .................................14
3.3.1. Set Format .........................................14
3.3.2. Set Header Format ..................................15
3.4. Record Format .............................................16
3.4.1. Template Record Format .............................16
3.4.2. Options Template Record Format .....................18
3.4.2.1. Scope .....................................19
3.4.2.2. Options Template Record Format ............20
3.4.3. Data Record Format .................................22
4. Specific Reporting Requirements ................................23
4.1. The Metering Process Statistics Option Template ...........23
4.2. The Metering Process Reliability Statistics Option
Template ..................................................24
4.3. The Exporting Process Reliability Statistics
Option Template ...........................................25
4.4. The Flow Keys Option Template .............................26
5. IPFIX Message Header "Export Time" and Flow Record Time ........27
6. Linkage with the Information Model .............................28
6.1. Encoding of IPFIX Data Types ..............................28
6.1.1. Integral Data Types ................................28
6.1.2. Address Types ......................................28
6.1.3. float32 ............................................28
6.1.4. float64 ............................................28
6.1.5. boolean ............................................28
6.1.6. string and octetarray ..............................28
6.1.7. dateTimeSeconds ....................................29
6.1.8. dateTimeMilliseconds ...............................29
6.1.9. dateTimeMicroseconds ...............................29
6.1.10.dateTimeNanoseconds.................................29
6.2. Reduced Size Encoding of Integer and Float Types ..........29
7. Variable-Length Information Element ............................30
8. Template Management ............................................31
9. The Collecting Process's Side ..................................34
10. Transport Protocol ............................................36
10.1. Transport Compliance and Transport Usage .................36
10.2. SCTP .....................................................37
10.2.1. Congestion Avoidance ..............................37
10.2.2. Reliability .......................................37
10.2.3. MTU ...............................................37
10.2.4. Exporting Process .................................38
10.2.4.1. Association Establishment ................38
10.2.4.2. Association Shutdown .....................38
10.2.4.3. Stream ...................................38
10.2.4.4. Template Management ......................39
10.2.5. Collecting Process ................................39
10.2.6. Failover ..........................................39
10.3. UDP ......................................................39
10.3.1. Congestion Avoidance ..............................39
10.3.2. Reliability .......................................40
10.3.3. MTU ...............................................40
10.3.4. Port Numbers ......................................40
10.3.5. Exporting Process .................................40
10.3.6. Template Management ...............................40
10.3.7. Collecting Process ................................41
10.3.8. Failover ..........................................42
10.4. TCP ......................................................42
10.4.1. Connection Management .............................42
10.4.1.1. Connection Establishment .................42
10.4.1.2. Graceful Connection Release ..............43
10.4.1.3. Restarting Interrupted Connections .......43
10.4.1.4. Failover .................................43
10.4.2. Data Transmission .................................43
10.4.2.1. IPFIX Message Encoding ...................43
10.4.2.2. Template Management ......................44
10.4.2.3. Congestion Handling and Reliability ......44
10.4.3. Collecting Process ................................45
11. Security Considerations .......................................46
11.1. Applicability of TLS and DTLS ............................47
11.2. Usage ....................................................48
11.3. Authentication ...........................................48
11.4. Protection against DoS Attacks ...........................48
11.5. When DTLS or TLS Is Not an Option ........................50
11.6. Logging an IPFIX Attack ..................................50
11.7. Securing the Collector ...................................51
12. IANA Considerations ...........................................51
Appendix A. IPFIX Encoding Examples ...............................52
A.1. Message Header Example.....................................52
A.2. Template Set Examples......................................53
A.2.1. Template Set Using IETF-Specified Information
Elements ...........................................53
A.2.2. Template Set Using Enterprise-Specific Information
Elements ...........................................53
A.3. Data Set Example ..........................................55
A.4. Options Template Set Examples .............................56
A.4.1. Options Template Set Using IETF-Specified
Information Elements ...............................56
A.4.2. Options Template Set Using Enterprise-Specific
Information Elements ...............................56
A.4.3. Options Template Set Using an Enterprise-Specific
Scope ..............................................57
A.4.4. Data Set Using an Enterprise-Specific Scope ........58
A.5. Variable-Length Information Element Examples ..............59
A.5.1. Example of Variable-Length Information Element
with Length Inferior to 255 Octets .................59
A.5.2. Example of Variable-Length Information Element
with Length 255 to 65535 Octets ....................59
References ........................................................59
Normative References ...........................................59
Informative References .........................................60
Acknowledgments ...................................................61
1. Introduction
A data network with IP traffic primarily consists of IP flows passing
through the network elements. It is often interesting, useful, or
even required to have access to information about these flows that
pass through the network elements for administrative or other
purposes. The IPFIX Collecting Process should be able to receive the
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 the protocol to achieve these aforementioned requirements.
This document specifies in detail the representation of different
flows, the additional data required for flow interpretation, packet
format, transport mechanisms used, security concerns, etc.
1.1. IPFIX Documents Overview
The IPFIX protocol provides network administrators with access to IP
flow information. The architecture for the export of measured IP
flow information out of an IPFIX Exporting Process to a Collecting
Process is defined in [IPFIX-ARCH], 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. IPFIX has a
formal description of IPFIX Information Elements, their name, type
and additional semantic information, as specified in [RFC5102].
Finally, [IPFIX-AS] describes what type of applications can use the
IPFIX protocol and how they can use the information provided. It
furthermore shows how the IPFIX framework relates to other
architectures and frameworks.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
The definitions of the basic terms like IP 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 [IPFIX-ARCH] are equivalent, except that 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 between some of the different terms defined.
Observation Point
An Observation Point is a location in the network where IP packets
can be observed. Examples include: a line to which a probe is
attached, a shared medium, such as an Ethernet-based LAN, a single
port of a router, or a set of interfaces (physical or logical) of
a router.
Note that every Observation Point is associated with an
Observation Domain (defined below), and that one Observation Point
may be a 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.
IP Traffic Flow or Flow
There are several definitions of the term 'flow' being used by the
Internet community. Within the context of IPFIX we use the
following definition:
A Flow is defined as a set of IP packets passing an Observation
Point in the network during a certain time interval. All packets
belonging to a particular Flow have a set of common properties.
Each property is defined as the result of applying a function to
the values of:
1. one or more packet header 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...).
3. one or more of fields derived from packet treatment (e.g.,
next hop IP address, the output interface, etc...).
A packet is defined as belonging to a Flow if it completely
satisfies all the defined properties of the Flow.
This definition covers the range from a Flow containing all
packets observed at a network interface to a Flow consisting of
just a single packet between two applications. It includes
packets selected by a sampling mechanism.
Flow Key
Each of the fields that:
1. belong to the packet header (e.g., destination IP address),
2. are a property of the packet itself (e.g., packet length),
3. are derived from packet treatment (e.g., Autonomous System
(AS) number),
and that are used to define a Flow are termed Flow Keys.
Flow Record
A Flow Record contains information about a specific Flow that was
observed at an Observation Point. A Flow Record contains measured
properties of the Flow (e.g., the total number of bytes for all
the Flow's packets) and usually characteristic properties of the
Flow (e.g., source IP address).
Metering Process
The Metering Process generates Flow Records. Inputs to the
process are packet headers and characteristics observed at an
Observation Point, and packet treatment at the Observation Point
(for example, the selected output interface).
The Metering Process consists of a set of functions that includes
packet header capturing, timestamping, sampling, classifying, and
maintaining Flow Records.
The maintenance of Flow Records may include creating new records,
updating existing ones, computing Flow statistics, deriving
further Flow properties, detecting Flow expiration, passing Flow
Records to the Exporting Process, and deleting Flow Records.
Exporting Process
The Exporting Process sends Flow Records to one or more Collecting
Processes. The Flow Records 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 arbitrary numbers of Observation
Points and Metering Processes.
Collecting Process
A Collecting Process receives Flow Records from one or more
Exporting Processes. The Collecting Process might process or
store received Flow Records, but such actions are out of scope for
this document.
Collector
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 at the Exporting Process
that carries the IPFIX records of this Exporting Process and whose
destination is a Collecting Process. An IPFIX Message is
encapsulated at the transport layer.
Message Header
The Message Header is the first part of an IPFIX Message, which
provides basic information about the message, such as the IPFIX
version, length of the message, message sequence number, etc.
Template Record
A Template Record defines the structure and interpretation of
fields in a Data Record.
Data Record
A Data Record is a record that contains values of the parameters
corresponding to a Template Record.
Options Template Record
An Options Template Record is a Template Record that defines the
structure and interpretation of fields in a Data Record, including
defining how to scope the applicability of the Data Record.
Set
Set is a generic term for a collection of records that have a
similar structure. In an IPFIX Message, one or more Sets follow
the Message Header.
There are three different types of Sets: Template Set, Options
Template Set, and Data Set.
Template Set
A Template Set is a collection of one or more Template Records
that have been grouped together in an IPFIX Message.
Options Template Set
An Options Template Set is a collection of one or more Options
Template Records that have been grouped together in an IPFIX
Message.
Data Set
A Data Set is one or more Data Records, of the same type, that are
grouped together in an IPFIX Message. Each Data Record is
previously defined by a Template Record or an Options Template
Record.
Information Element
An Information Element is a protocol and encoding-independent
description of an attribute that may appear in an IPFIX Record.
The IPFIX information model [RFC5102] defines the base set of
Information Elements for IPFIX. The type associated with an
Information Element indicates constraints on what it may contain
and also determines the valid encoding mechanisms for use in
IPFIX.
Transport Session
In Stream Control Transmission Protocol (SCTP), the transport
session is known as the SCTP association, which is uniquely
identified by the SCTP endpoints [RFC4960]; in TCP, the 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 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
+------------------+---------------------------------------------+
| | 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 one or
more Sets. The Sets can be any of the possible three 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
The Exporter MUST code all binary integers of the Message Header and
the different Sets in network-byte order (also known as the
big-endian byte ordering).
Following are some examples of IPFIX Messages:
1. An IPFIX Message consisting of interleaved Template, Data, and
Options Template Sets -- A newly created Template is exported as
soon as possible. So, if there is already an IPFIX Message with a
Data Set that is being prepared for export, the Template and
Option Template Sets are interleaved with this information,
subject to availability of space.
+--------+--------------------------------------------------------+
| | +----------+ +---------+ +-----------+ +---------+ |
|Message | | Template | | Data | | Options | | Data | |
| Header | | Set | | Set | ... | Template | | Set | |
| | | | | | | Set | | | |
| | +----------+ +---------+ +-----------+ +---------+ |
+--------+--------------------------------------------------------+
Figure C: IPFIX Message, Example 1
2. An IPFIX Message consisting entirely of Data Sets -- After the
appropriate Template Records have been defined and transmitted to
the Collecting Process, the majority of IPFIX Messages consist
solely of Data Sets.
+--------+----------------------------------------------+
| | +---------+ +---------+ +---------+ |
|Message | | Data | | Data | | Data | |
| Header | | Set | ... | Set | ... | Set | |
| | +---------+ +---------+ +---------+ |
+--------+----------------------------------------------+
Figure D: IPFIX Message, Example 2
3. An IPFIX Message consisting entirely of Template and Options
Template Sets.
+--------+-------------------------------------------------+
| | +----------+ +----------+ +----------+ |
|Message | | Template | | Template | | Options | |
| Header | | Set | ... | Set | ... | Template | |
| | | | | | | Set | |
| | +----------+ +----------+ +----------+ |
+--------+-------------------------------------------------+
Figure E: IPFIX 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
Message Header Field Descriptions:
Version
Version of Flow Record format exported in this message. 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, in seconds, since 0000 UTC Jan 1, 1970, at which the IPFIX
Message Header leaves the Exporter.
Sequence Number
Incremental sequence counter modulo 2^32 of all IPFIX Data Records
sent on this PR-SCTP stream from the current Observation Domain by
the Exporting Process. Check the specific meaning of this field
in the subsections of Section 10 when UDP or TCP is selected as
the transport protocol. This value SHOULD be used by the
Collecting Process to identify whether any IPFIX Data Records have
been missed. Template and Options Template Records do not
increase the Sequence Number.
Observation Domain ID
A 32-bit identifier of the Observation Domain that is locally
unique to the Exporting Process. The Exporting Process uses the
Observation Domain ID to uniquely identify to the Collecting
Process the Observation Domain that metered the Flows. It is
RECOMMENDED that this identifier also be unique per IPFIX Device.
Collecting Processes SHOULD use the Transport Session and the
Observation Domain ID field to separate different export streams
originating from the same Exporting Process. The Observation
Domain ID SHOULD be 0 when no specific Observation Domain ID is
relevant for the entire IPFIX Message, for example, when exporting
the Exporting Process Statistics, or in case of a hierarchy of
Collectors when aggregated Data Records are exported.
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, in some way, commercially sensitive.
This section describes the Field Specifier format for both
IETF-specified Information Elements [RFC5102] and 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 identifier will report an IETF-specified
Information Element, and the Enterprise Number MUST NOT be present.
When the Enterprise bit is set to 1, the corresponding Information
Element identifier will report an enterprise-specific Information
Element; the Enterprise Number MUST be present. An example of this
is shown in Section A.4.2.
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:
E
Enterprise bit. This is the first bit of the Field Specifier. If
this bit is zero, the Information Element Identifier identifies an
IETF-specified Information Element, 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 filed MUST be
present.
Information Element identifier
A numeric value that represents the type of Information Element.
Refer to [RFC5102].
Field Length
The length of the corresponding encoded Information Element, in
octets. Refer to [RFC5102]. The field length may be smaller than
the definition in [RFC5102] if the 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] 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
The Set Field Definitions are as follows:
Set Header
The Set Header Format is defined in Section 3.3.2.
Record
One of the record Formats: Template Record, Options Template
Record, or Data Record 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 zero (0) valued
octets. 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' [RFC5102] 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 case of other 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
The Set Header Field Definitions are as follows:
Set ID
Set ID value identifies the Set. A value of 2 is reserved for the
Template Set. A value of 3 is reserved for the Option Template
Set. All other values from 4 to 255 are reserved for future use.
Values above 255 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, defined in the next sections: the
Template Record Format, the Options Template Record Format, and the
Data Record 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 and/or enterprise-specific Information Elements
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 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 are as follows:
Template ID
Each of the newly generated Template Records is given a unique
Template ID. This uniqueness is local to the Transport Session
and Observation Domain that generated the Template ID. Template
IDs 0-255 are reserved for Template Sets, Options Template Sets,
and other reserved Sets yet to be created. Template IDs of Data
Sets are numbered from 256 to 65535. There are no constraints
regarding the order of the Template ID allocation.
Field Count
Number of fields in this Template Record.
The example in Figure L shows a Template Set with mixed standard 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 1.2 and 2.1 are defined by the IETF
(Enterprise bit = 0) 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.
One Options Template Record example is the "Flow Keys", which reports
the Flow Keys for a Template, which is defined as the scope. Another
example is the "Template configuration", which reports the
configuration sampling parameter(s) for the Template, which is
defined as the scope.
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.
Note that the IPFIX Message Header already contains the Observation
Domain ID (the identifier of the Observation Domain). If not zero,
this Observation Domain ID can be considered as an implicit scope for
the Data Records in the IPFIX Message. The Observation Domain ID
MUST be zero when the IPFIX Message contains Data Records with
different Observation Domain ID values defined as scopes.
Multiple Scope Fields MAY be present in the Options Template Record,
in which case, the composite scope is the combination of the scopes.
For example, if the two scopes are defined as "metering process" and
"template", the combined scope is this Template for this Metering
Process. The order of the Scope Fields, as defined in the Options
Template Record, is irrelevant in this case. However, if the order
of the Scope Fields in the Options Template Record is relevant, the
order of the Scope Fields MUST be used. For example, 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. In this
case, the Collector deduces the function order by looking at the
order of the scope in the Options Template Record.
The scope is an Information Element specified in the IPFIX
Information Model [RFC5102]. An IPFIX-compliant implementation of
the Collecting Process SHOULD support this minimum set of Information
Elements as scope: LineCardId, TemplateId, exporterIPv4Address,
exporterIPv6Address, and ingressInterface. Note that other
Information Elements, such as meteringProcessId, exportingProcessId,
observationDomainId, etc. are also valid scopes. 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 example, the counter Information Elements.
Finally, note that the Scope Field Count MUST NOT be zero.
3.4.2.2. Options Template Record Format
An Options Template Record contains any combination of IANA-assigned
and/or enterprise-specific Information Elements 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 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.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure N: Options Template Record Header Format
The Options Template Record Header Field Definitions are as follows:
Template ID
Template ID of this Options Template Record. This value is greater
than 255.
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 except that they are interpreted as scope at
the Collector. The Scope Field Count MUST NOT be zero.
The example in Figure O shows an Option Template Set with mixed IETF
and enterprise-specific Information Elements. It consists of a Set
Header, an Option 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. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length |0| Scope 2 Infor. Element Id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 2 Field Length | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |1| Scope N Infor. Element Id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope N Field Length | Scope N Enterprise Number ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Scope N Enterprise Number |1| Option 1 Infor. Element Id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option 1 Field Length | Option 1 Enterprise Number ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Option 1 Enterprise Number | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |0| Option M Infor. Element Id. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option M Field Length | Padding (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure O: Option 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 specified in
[RFC5102].
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 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 Option 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 Option 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.
4.1. The Metering Process Statistics Option Template
The Metering Process Statistics Option Template specifies the
structure of a Data Record for reporting Metering Process statistics.
It SHOULD contain the following Information Elements that are defined
in [RFC5102]:
observationDomainId
An identifier of an Observation Domain that
is locally unique to the Exporting Process.
This Information Element MUST be defined as a
Scope Field.
exportedMessageTotalCount
The total number of IPFIX Messages that the
Exporting Process successfully sent to the
Collecting Process since the Exporting
Process re-initialization.
exportedFlowTotalCount
The total number of Flow Records that the
Exporting Process successfully sent to the
Collecting Process since the Exporting
Process re-initialization.
exportedOctetTotalCount
The total number of octets that the Exporting
Process successfully sent to the Collecting
Process since the Exporting Process re-
initialization.
The Exporting Process SHOULD export the Data Record specified by the
Metering Process Statistics Option 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 Option Template
The Metering Process Reliability Option Template specifies the
structure of a Data Record for reporting lack of reliability in the
Metering Process. It SHOULD contain the following Information
Elements that are defined in [RFC5102]:
observationDomainId
An identifier of an Observation Domain that
is locally unique to the Exporting Process.
This Information Element MUST be defined as a
Scope Field.
ignoredPacketTotalCount
The total number of IP packets that the
Metering Process did not process.
ignoredOctetTotalCount
The total number of octets in observed IP
packets that the Metering Process did not
process.
time first ignored
The timestamp of the first IP packet that was
ignored by the Metering Process. For this
timestamp, any of the "flowStart" timestamp
Information Elements flowStartMilliseconds,
flowStartMicroseconds, flowStartNanoseconds,
and flowStartDeltaMicroseconds can be used.
time last ignored
The timestamp of the last IP packet that was
ignored by the Metering Process. For this
timestamp, any of the "flowEnd" timestamp
Information Elements flowEndMilliseconds,
flowEndMicroseconds, flowEndNanoseconds, and
flowEndDeltaMicroseconds can be used.
The Exporting Process SHOULD export the Data Record specified by the
Metering Process Reliability Statistics Option 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.
4.3. The Exporting Process Reliability Statistics Option Template
The Exporting Process Reliability Option Template specifies the
structure of a Data Record for reporting lack of reliability in the
Exporting process. It SHOULD contain the following Information
Elements that are defined in [RFC5102]:
Exporting Process ID
The identifier of the Exporting Process for
which lack of reliability is reported. There
are three Information Elements specified in
[RFC5102] that can be used for this purpose:
exporterIPv4Address, exporterIPv6Address, or
exportingProcessId. This Information Element
MUST be defined as a Scope Field.
notSentFlowTotalCount
The total number of Flows that were generated by
the Metering Process and dropped by the Metering
Process or by the Exporting Process instead of
being sent to the Collecting Process.
notSentPacketTotalCount
The total number of packets in Flow Records that
were generated by the Metering Process and
dropped by the Metering Process or by the
Exporting Process instead of being sent to the
Collecting Process.
notSentOctetTotalCount
The total number of octets in packets in Flow
Records that were generated by the Metering
Process and dropped by the Metering Process or
by the Exporting Process instead of being sent
to the Collecting Process.
time first flow dropped
The timestamp of the first Flow was dropped by
the Metering Process. For this timestamp, any
of the "flowStart" timestamp Information
Elements flowStartMilliseconds,
flowStartMicroseconds, flowStartNanoseconds, and
flowStartDeltaMicroseconds can be used.
time last flow dropped
The timestamp of the last IP packet that was
ignored by the Metering Process. For this
timestamp, any of the "flowEnd" timestamp
Information Elements flowEndMilliseconds,
flowEndMicroseconds, flowEndNanoseconds, and
flowEndDeltaMicroseconds can be used.
The Exporting Process SHOULD export the Data Record specified by the
Exporting Process Reliability Statistics Option Template on a regular
basis or based on some export policy. This periodicity or export
policy SHOULD be configurable.
4.4. The Flow Keys Option Template
The Flow Keys Option Template specifies the structure of a Data
Record for reporting the Flow Keys of reported Flows. A Flow Keys
Data Record extends a particular Template Record that is referenced
by its templateId identifier. The Template Record is extended by
specifying which of the Information Elements contained in the
corresponding Data Records describe Flow properties that serve as
Flow Keys of the reported Flow.
The Flow Keys Option Template SHOULD contain the following
Information Elements that are defined in [RFC5102]:
templateId An identifier of a Template. This
Information Element MUST be defined as a
Scope Field.
flowKeyIndicator Bitmap with the positions of the Flow Keys in
the Data Records.
5. IPFIX Message Header "Export Time" and Flow Record Time
The IPFIX Message Header "Export Time" field is the time in seconds
since 0000 UTC Jan 1, 1970, at which the IPFIX Message Header leaves
the Exporter. The time-related Information Elements specified in
[RFC5102] MAY use this "Export Time" as base time and specify an
offset relative to it, instead of using a common base time, such as
0000 UTC Jan 1, 1970. All Information Elements that do not have
their base time defined by their data type MUST have the base time
clearly specified in their description.
For example, Data Records requiring a microsecond precision can
export the flow start and end times with the flowStartMicroseconds
and flowEndMicroseconds Information Elements [RFC5102], containing
the time since 0000 UTC Jan 1, 1970. An alternate solution is to
export the flowStartDeltaMicroseconds and flowEndDeltaMicroseconds
Information Elements [RFC5102] in the Data Record, which respectively
report the flow start and end time offsets compared to the IPFIX
Message Header "Export Time". The latter solution lowers the export
bandwidth requirement while it increases 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 using time-related Information Elements with
offset times, compared to the IPFIX Message Header "Export Time",
imposes some time constraints on the Data Records contained in the
IPFIX Message. In the example of flowStartDeltaMicroseconds and
flowEndDeltaMicroseconds Information Elements [RFC5102], the Data
Record must be exported within a maximum of 71 minutes after its
creation. Otherwise, the 32-bit counter would not be sufficient to
contain the flow start time offset.
6. Linkage with the Information Model
The Information Elements [RFC5102] MUST be sent in canonical format
in network-byte order (also known as the big-endian byte ordering).
6.1. Encoding of IPFIX Data Types
The following sections will define the encoding of the data types
specified in [RFC5102].
6.1.1. Integral Data Types
Integral data types -- octet, signed8, unsigned16, signed16,
unsigned32, signed32, signed64, and unsigned64 -- MUST be encoded
using the default canonical format in network-byte order. Signed
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. The macAddress is
treated as a 6-octet integer, the ipv4Address as a 4-octet integer,
and the ipv6Address as a 16-octet integer.
6.1.3. float32
The float32 data type MUST be encoded as an IEEE single-precision
32-bit floating point-type, as specified in [IEEE.754.1985].
6.1.4. float64
The float64 data type MUST be encoded as an IEEE double-precision
64-bit floating point-type, as specified in [IEEE.754.1985].
6.1.5. boolean
The boolean data type is specified according to the TruthValue in
[RFC2579]: it is an integer with the value 1 for true and a value 2
for false. Every other value is undefined. The boolean data type
MUST be encoded in a single octet.
6.1.6. string and octetarray
The data type string represents a finite length string of valid
characters of the Unicode character encoding set. The string data
type MUST be encoded in UTF-8 format. The string is sent as an array
of octets using an Information Element of fixed or variable length.
The length of the Information Element specifies the length of the
octetarray.
6.1.7. dateTimeSeconds
The data type dateTimeseconds represents a time value in units of
seconds normalized to the GMT timezone. It MUST be encoded in a
32-bit integer containing the number of seconds since 0000 UTC Jan 1,
1970. The 32-bit integer allows the time encoding up to 136 years.
6.1.8. dateTimeMilliseconds
The data type dateTimeMilliseconds represents a time value in units
of milliseconds normalized to the GMT timezone. It MUST be encoded
in a 64-bit integer containing the number of milliseconds since 0000
UTC Jan 1, 1970.
6.1.9. dateTimeMicroseconds
The data type dateTimeMicroseconds represents a time value in units
of microseconds normalized to the GMT timezone. It MUST be encoded
in a 64-bit integer, according to the NTP format given in [RFC1305].
6.1.10. dateTimeNanoseconds
The data type of dateTimeNanoseconds represents a time value in units
of nanoseconds normalized to the GMT time zone. It MUST be encoded
in a 64-bit integer, according to the NTP format given in [RFC1305].
6.2. Reduced Size Encoding of Integer and Float Types
Information Elements containing integer, string, float, and
octetarray types in the information model MAY be encoded using fewer
octets than those implied by their type in the information model
definition [RFC5102], 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
[RFC5102] will always define the maximum encoding size.
For instance, the information model [RFC5102] defines byteCount 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 to send the value instead as an
unsigned32. For example, a core router would require an unsigned64
byteCount, while an unsigned32 might be sufficient for an access
router.
This behavior is indicated by the Exporter by specifying a type size
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.
If reduced sizing is used, it MUST only 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 sizing can also be used to reduce float64 to float32. The
float32 not only has a reduced number range, but due to the smaller
mantissa, is also less precise.
The reduced size encoding MUST NOT be applied to dateTimeMicroseconds
or to dateTimeNanoseconds because these represent an inherent
structure that would be destroyed by using less than the original
number of bytes.
7. Variable-Length Information Element
The IPFIX Template mechanism is optimized for fixed-length
Information Elements [RFC5102]. Where an Information Element has a
variable length, the following mechanism MUST be used to carry the
length information for both the IETF and proprietary Information
Elements.
In the Template Set, the Information Element Field Length is recorded
as 65535. This reserved length value notifies the Collecting Process
that length 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 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 < 255 octets)
If the length of the Information Element is greater than or equal to
255 octets, the length is encoded into 3 octets before the
Information Element. The first octet is 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 0 to 65535
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 Template Management when using SCTP and
PR-SCTP as the transport protocol. Any necessary changes to Template
Management specifically related to TCP or UDP transport protocols are
specified in Section 10.
The Exporting Process assigns and maintains the Template IDs per SCTP
association for the Exporter's Observation Domains. A newly created
Template Record is assigned an unused Template ID by the Exporting
Process.
If a specific Information Element is required by a Template, but is
not available in observed packets, the Exporting Process MAY choose
to export Flow Records without this Information Element in a Data
Record defined 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 packets, the first sourceIPv4Address
Information Element occurrence should be the IPv4 address of the
outer header, while the second occurrence should be the inner header
one.
Template Sets and Options Template Sets may be sent on any SCTP
stream. Template Sets and Options Template Sets MUST be sent
reliably, using SCTP-ordered delivery. As such, the Collecting
Process MUST store the Template Record information for the duration
of the SCTP association so that it can interpret the corresponding
Data Records that are received in subsequent Data Sets.
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).
Different Observation Domains from the same SCTP association may use
the same Template ID value to refer to different Templates.
The Templates that are not used anymore SHOULD be deleted. Before
reusing a Template ID, the Template MUST be deleted. In order to
delete an allocated Template, the Template is withdrawn through the
use of a Template Withdrawal Message.
The Template Withdrawal Message MUST NOT be sent until sufficient
time has elapsed to allow the Collecting Process to receive and
process the last Data Record using this Template information. This
time MUST be configurable. A suitable default value is 5 seconds
after the last Data Record has been sent.
The Template ID from a withdrawn Template MUST NOT be reused until
sufficient time has elapsed to allow for the Collecting Process to
receive and process the Template Withdrawal Message.
A Template Withdrawal Message is a Template Record for that Template
ID with a Field Count of 0. The format of the Template Withdrawal
Message is shown in Figure T.
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 or 3) | Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID N | Field Count = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID ... | Field Count = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID M | Field Count = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure T: Template Withdrawal Message Format
The Set ID field MUST contain the value 2 for Template Set Withdrawal
and the value 3 for Options Template Set Withdrawal. Multiple
Template IDs MAY be withdrawn with a single Template Withdrawal
Message, in that case, padding MAY be used.
The Template Withdrawal Message withdraws the Template IDs for the
Observation Domain ID specified in the IPFIX Message Header.
The Template Withdrawal Message may be sent on any SCTP stream. The
Template Withdrawal Message MUST be sent reliably, using SCTP-ordered
delivery.
The Template Withdrawal Message MUST NOT contain new Template or
Options Template Records.
If the measurement parameters change such that a new Template is
required, the Template MUST be withdrawn (using a Template Withdraw
Message and a new Template definition) or an unused Template ID MUST
be used. Examples of the measurement changes are: a new sampling
rate, a new Flow expiration process, a new filtering definition, etc.
When the SCTP association shuts down or the Exporting Process
restarts, all Template assignments are lost and Template IDs MUST be
reassigned.
If the Metering Process restarts, the Exporting Process MUST either
reuse the previously assigned Template ID for each Template, or it
MUST withdraw the previously issued Template IDs by sending Template
Withdraw Message(s) before reusing them.
A Template Withdrawal Message to withdraw all Templates for the
Observation Domain ID specified in the IPFIX Message Header MAY be
used. Its format is shown in Figure U.
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 Data Templates Withdrawal Message Format
A Template Withdrawal Message to withdraw all Options Templates for
the Observation Domain ID specified in the IPFIX Message Header MAY
be used. Its format is shown in Figure 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 = 3 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 3 | Field Count = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure V: All Options Templates Withdrawal Message Format
When the SCTP association restarts, the Exporting Process MUST resend
all the Template Records.
9. The Collecting Process's Side
This section describes the Collecting Process when using SCTP and
PR-SCTP as the transport protocol. Any necessary changes to the
Collecting Process specifically related to TCP or UDP transport
protocols are specified in Section 10.
The Collecting Process SHOULD listen for a new association request
from the Exporting Process. The Exporting Process will request a
number of streams to use for export. An Exporting Process MAY
request and support more than one stream per SCTP association.
If the Collecting Process receives a malformed IPFIX Message, it MUST
reset the SCTP association, discard the IPFIX Message, and SHOULD log
the error. Note that non-zero Set padding does not constitute a
malformed IPFIX Message.
Template Sets and Option Template Sets are only sent once. The
Collecting Process MUST store the Template Record information for the
duration of the association so that it can interpret the
corresponding Data Records that are received in subsequent Data Sets.
Template IDs are unique per SCTP association and per Observation
Domain. If the Collecting Process receives a Template that has
already been received but that has not previously been withdrawn
(i.e., a Template Record from the same Exporter Observation Domain
with the same Template ID received on the SCTP association), then the
Collecting Process MUST shut down the association.
When an SCTP association is closed, the Collecting Process MUST
discard all Templates received over that association and stop
decoding IPFIX Messages that use those Templates.
The Collecting Process normally receives Template Records from the
Exporting Process before receiving Data Records. The Data Records
are then decoded and stored by the Collector. If the Template
Records 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 are received. 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.
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 the Flow Record.
The Collector 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
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 may 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.
If a Collecting Process receives a Template Withdrawal Message, the
Collecting Process MUST delete the corresponding Template Records
associated with the specific SCTP association and specific
Observation Domain, and stop decoding IPFIX Messages that use the
withdrawn Templates.
If the Collecting Process receives a Template Withdraw message for a
Template Record it has not received before on this SCTP association,
it MUST reset the SCTP association, discard the IPFIX Message, and
SHOULD log the error as it does for malformed IPFIX Messages.
A Collecting Process that receives IPFIX Messages from several
Observation Domains on the same Transport Session MUST be aware that
the uniqueness of the Template ID is not guaranteed across
Observation Domains.
The Collector MUST support the use of Templates containing multiple
occurrences of the similar Information Elements.
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.
10.1. Transport Compliance and Transport Usage
We need to differentiate between what must be implemented (so that
operators can interoperably deploy compliant implementations from
different vendors) and what should or could be used in various
operational environments. We must also make sure that ALL
implementations can operate in a congestion-aware and
congestion-avoidance mode.
SCTP [RFC4960] using the PR-SCTP extension 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.
PR-SCTP SHOULD be used in deployments where Exporters and Collectors
are communicating over links that are susceptible to congestion.
PR-SCTP is capable of providing any required degree of reliability.
TCP MAY be used in deployments where Exporters and Collectors
communicate over links that are susceptible to congestion, but
PR-SCTP is preferred due to its ability to limit back pressure on
Exporters and its message versus stream orientation.
UDP MAY be used, although it is not a congestion-aware protocol.
However, the IPFIX traffic between Exporter and Collector MUST run in
an environment where IPFIX traffic has been provisioned for, or is
contained through some other means.
10.2. SCTP
This section describes how IPFIX can be 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 will detect congestion in the end-to-end path between the IPFIX
Exporting Process and the IPFIX Collecting Process, and limit the
transfer rate accordingly. When an IPFIX Exporting Process has
records to export, but detects that transmission by SCTP is
temporarily impossible, it can either wait until sending is possible
again, or it can decide to drop the record. In the latter case, the
dropped export data MUST be accounted for, so that the amount of
dropped export data can be reported.
10.2.2. Reliability
The SCTP transport protocol is by default 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 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 MTU discovery.
10.2.4. Exporting Process
10.2.4.1. Association Establishment
The IPFIX Exporting Process SHOULD initiate an SCTP association with
the IPFIX Collecting Process. By default, the Collecting Process
listens for connections on SCTP port 4739. By default, the
Collecting Process listens for secure connections on SCTP port 4740
(refer to the Security Considerations section). By default, the
Exporting Process tries to connect to one of these ports. It MUST be
possible to configure both the Exporting and Collecting Processes to
use a different SCTP port.
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).
10.2.4.2. Association Shutdown
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.
10.2.4.3. Stream
An Exporting Process MAY request more than one SCTP 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 established
during SCTP Association setup.
An IPFIX Exporting Process MAY use any PR-SCTP Service Definition as
per Section 4 of the PR-SCTP [RFC3758] specification 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.
10.2.4.4. Template Management
When the transport protocol is SCTP, the default Template Management
described in Section 8 is used.
10.2.5. Collecting Process
When the transport protocol is SCTP, the default Collector processing
described in Section 9 is used.
10.2.6. Failover
If the Collecting Process does not acknowledge the attempt by the
Exporting Process to establish an association, the Exporting Process
should retry using the SCTP exponential backoff feature. The
Exporter MAY log an alarm if the time to establish the association
exceeds a specified threshold, configurable on the Exporter.
If Collecting Process failover is supported by the Exporting Process,
a second SCTP association MAY be opened in advance.
10.3. UDP
This section describes how IPFIX can be 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., over provisioned links compared to the maximum
export rate from the Exporters.
10.3.2. Reliability
UDP is not a reliable transport 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. Templates sent from the Exporting
Process to the Collecting Process using UDP as a transport MUST be
re-sent at regular intervals, in case previous copies were lost.
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. If the path MTU
is unknown, a maximum packet size of 512 octets SHOULD be used.
10.3.4. Port Numbers
By default, the Collecting Process listens on the UDP port 4739. By
default, the Collecting Process listens for secure connections on UDP
port 4740 (refer to the "Security Considerations" section). By
default, the Exporting Process tries to connect to one of these
ports. It MUST be possible to configure both the Exporting and
Collecting Processes to use a different UDP port.
10.3.5. Exporting Process
The Exporting Process MAY duplicate the IPFIX Message to the several
Collecting Processes.
10.3.6. Template Management
When IPFIX uses UDP as the transport protocol, Template Sets and
Option Template Sets MUST be re-sent at regular intervals. The
frequency of the (Options) Template transmission MUST be
configurable. The default value for the frequency of the (Options)
Template transmission is 10 minutes. 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.
In the event of configuration changes, the Exporting Process SHOULD
send multiple copies of the new Template definitions, in different
IPFIX Messages, at an accelerated rate. In such a case, it SHOULD
transmit the changed Template Record(s) and Options Template
Record(s), without any data, in advance to help ensure that the
Collector will have the correct Template information before receiving
the first data.
If the Option Template scope is defined in another Template, then
both Templates SHOULD be sent in the same IPFIX Message. For
example, if a Flow Key Option Template (see Section 4.4) is sent in
an Option Template, then the associated Template SHOULD be sent in
the same IPFIX Message.
Following a configuration change that can modify the interpretation
of the Data Records (for example, a sampling rate change) a new
Template ID MUST be used, and the old Template ID MUST NOT be reused
until its lifetime (see Section 10.3.7) has expired.
If UDP is selected as the transport protocol, the Template Withdraw
Messages MUST NOT be used, as this method is inefficient due to the
unreliable nature of UDP.
10.3.7. Collecting Process
The Collecting Process MUST associate a lifetime with each Template
(or another definition of an identifier considered unique within the
Transport Session) received via UDP. Templates (and similar
definitions) not refreshed by the Exporting Process within the
lifetime are expired at the Collecting Process. If the Template (or
other definition) is not refreshed before that lifetime has expired,
the Collecting Process MUST discard that definition and any current
and future associated Data Records. In which case, an alarm MUST be
logged. The Collecting Process MUST NOT decode any further Data
Records that are associated with the expired Template. If a Template
is refreshed with a Template Record that differs from the previously
received Template Record, the Collecting Process SHOULD log a warning
and replace the previously received Template Record with the new one.
The Template lifetime at the Collecting Process MUST be at least 3
times higher than the Template refresh timeout configured on the
Exporting Process.
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, Observation Domain
ID, Template ID, Template Definition, Last Received>.
The Collecting Process SHOULD accept Data Records without the
associated Template Record (or other definitions) required to decode
the Data Record. If the Template Records (or other definitions such
as Common Properties) have not been received at the time Data Records
are received, the Collecting Process SHOULD store the Data Records
for a short period of time and decode them after the Template Records
(or other definitions) are received. The short period of time MUST
be lower than the lifetime of definitions associated with identifiers
considered unique within the UDP session.
If the Collecting Process receives a malformed IPFIX Message, it MUST
discard the IPFIX Message and SHOULD log the error.
10.3.8. Failover
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 can be transported over TCP [TCP].
10.4.1. Connection Management
10.4.1.1. Connection Establishment
The IPFIX Exporting Process initiates a TCP connection to the
Collecting Process. By default, the Collecting Process listens for
connections on TCP port 4739. By default, the Collecting Process
listens for secure connections on TCP port 4740 (refer to the
Security Considerations section). By default, the Exporting Process
tries to connect to one of these ports. It MUST be possible to
configure both the Exporting Process and the Collecting Process to
use a different TCP port.
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).
The Exporter MAY log an alarm if the time to establish the connection
exceeds a specified threshold, configurable on the Exporter.
10.4.1.2. Graceful Connection Release
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.
10.4.1.3. Restarting Interrupted Connections
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.
10.4.1.4. Failover
If the Collecting Process does not acknowledge the attempt by the
Exporting Process to establish a connection, it will retry using the
TCP exponential backoff feature.
If Collecting Process failover is supported by the Exporting Process,
a second TCP connection MAY be opened in advance.
10.4.2. Data Transmission
Once a TCP connection is established, the Exporting Process starts
sending IPFIX Messages to the Collecting Process.
10.4.2.1. IPFIX Message Encoding
IPFIX Messages are sent over the TCP connection without any special
encoding. The Length field in the IPFIX Message Header defines the
end of each IPFIX Message and thus the start of the next IPFIX
Message. This means that IPFIX Messages cannot be interleaved.
In the case of TCP, the IPFIX Sequence Number contains the total
number of IPFIX Data Records sent from this TCP connection, from the
current Observation Domain by the Exporting Process, prior to the
receipt of this IPFIX Message, modulo 2^32.
If an Exporting Process exports data from multiple Observation
Domains, it should be careful to choose IPFIX Message lengths
appropriately to minimize head-of-line blocking between different
Observation Domains. Multiple TCP connections MAY be used to avoid
head-of-line between different Observation Domains.
10.4.2.2. Template Management
For each Template, the Exporting Process MUST send the Template
Record before exporting Data Records that refer to that Template.
Template IDs are unique per TCP connection and per Observation
Domain. A Collecting Process MUST record all Template and Options
Template Records for the duration of the connection, as an Exporting
Process is not required to re-export Template Records.
When the TCP connection restarts, the Exporting Process MUST resend
all the Template Records.
When a TCP connection is closed, the Collecting Process MUST discard
all Templates received over that connection and stop decoding IPFIX
Messages that use those Templates.
The Templates that are not used anymore SHOULD be deleted. Before
reusing a Template ID, the Template MUST be deleted. In order to
delete an allocated Template, the Template is withdrawn through the
use of a Template Withdrawal Message over the TCP connection.
If the Collecting Process receives a malformed IPFIX Message, it MUST
reset the TCP connection, discard the IPFIX Message, and SHOULD log
the error.
10.4.2.3. Congestion Handling and Reliability
TCP ensures reliable delivery of data from the Exporting Process to
the Collecting Process. TCP also 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 it, 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 amount can later be exported.
When an Exporting Process finds that the rate at which records should
be exported is consistently higher than the rate at which TCP sending
permits, it should provide back pressure to the Metering Processes.
The Metering Process could then adapt by temporarily reducing the
amount of data it generates, for example, using sampling or
aggregation.
10.4.3. Collecting Process
The Collecting Process SHOULD listen for a new TCP connection from
the Exporting Process.
If the Collecting Process receives a malformed IPFIX Message, it MUST
reset the TCP connection, discard the IPFIX Message, and SHOULD log
the error. Note that non-zero Set padding does not constitute a
malformed IPFIX Message.
Template Sets and Option Template Sets are only sent once. The
Collecting Process MUST store the Template Record information for the
duration of the connection so that it can interpret the corresponding
Data Records that are received in subsequent Data Sets.
Template IDs are unique per TCP connection and per Observation
Domain. If the Collecting Process receives a Template that has
already been received but that has not previously been withdrawn
(i.e., a Template Record from the same Exporter Observation Domain
with the same Template ID received on the TCP connection), then the
Collecting Process MUST shut down the connection.
When a TCP connection is closed, the Collecting Process MUST discard
all Templates received over that connection and stop decoding IPFIX
Messages that use those Templates.
If a Collecting Process receives a Template Withdrawal Message, the
Collecting Process MUST delete the corresponding Template Records
associated with the specific TCP connection and specific Observation
Domain, and stop decoding IPFIX Messages that use the withdrawn
Templates.
If the Collecting Process receives a Template Withdrawal Message for
a Template Record it has not received before on this TCP connection,
it MUST reset the TCP association, discard the IPFIX Message, and
SHOULD log the error as it does for malformed IPFIX Messages.
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" section of IPFIX requirements [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) into 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 the application using IPFIX (by
falsifying 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 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,
anonymization of any reported data.
11.1. Applicability of TLS and DTLS
Transport Layer Security (TLS) [RFC4346] and Datagram Transport Layer
Security (DTLS) [RFC4347] were designed to provide the
confidentiality, integrity, and authentication assurances required by
the IPFIX protocol, without the need for pre-shared keys.
With the mandatory SCTP and PR-SCTP transport protocols for IPFIX,
DTLS [RFC4347] MUST be implemented. If UDP is selected as the IPFIX
transport protocol, DTLS [RFC4347] MUST be implemented. If TCP is
selected as the IPFIX transport protocol, TLS [RFC4346] MUST be
implemented.
Note that DTLS is selected as the security mechanism for SCTP and
PR-SCTP. Though TLS bindings to SCTP are defined in [RFC3436], they
require all communication to be over reliable, bidirectional streams,
and 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 [RFC4347] has a vulnerability, i.e., a true man
in the middle may attempt to take data out of an association and fool
the sender into thinking that the data was actually received by the
peer. In generic TLS for SCTP (and/or TCP), this is not possible.
This means that the removal of a message may become hidden from the
sender or receiver. Another vulnerability of using PR-SCTP with DTLS
is that someone could inject SCTP control information to shut down
the SCTP association, effectively generating a loss of IPFIX Messages
if those are buffered outside of the SCTP association. In the
future, techniques such as [dtls-for-sctp] 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 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.
11.2. Usage
The IPFIX Exporting Process initiates the communication to the IPFIX
Collecting Process, and acts as a TLS or DTLS client according to
[RFC4346] and [RFC4347], 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 or PR-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. Authentication
IPFIX Exporting Processes and IPFIX Collecting Processes are
identified by the fully qualified domain name of the interface on
which IPFIX Messages are sent or received, for purposes of X.509
client and server certificates as in [RFC3280].
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, strong mutual authentication via asymmetric keys
MUST be used for both TLS and DTLS. Each of the IPFIX Exporting and
Collecting Processes MUST verify the identity of its peer against its
authorized certificates, and MUST verify that the peer's certificate
matches its fully qualified domain name, or, in the case of SCTP, the
fully qualified domain name of one of its endpoints.
The fully qualified domain name used to identify an IPFIX Collecting
Process or Exporting Process may be stored either in a subjectAltName
extension of type dNSName, or in the most specific Common Name field
of the Subject field of the X.509 certificate. If both are present,
the subjectAltName extension is given preference.
Internationalized domain names (IDN) in either the subjectAltName
extension of type dNSName or the most specific Common Name field of
the Subject field of the X.509 certificate MUST be encoded using
Punycode [RFC3492] as described in Section 4 of [RFC3490],
"Conversion Operations".
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 denial-of-service attacks can also involve state exhaustion,
whether at the transport layer (e.g., by creating a large number of
pending connections), or within the IPFIX Collecting Process itself
(e.g., by sending Flow Records pending Template or scope information,
a large amount of Options Template Records, etc.).
SCTP mandates a cookie-exchange mechanism designed to defend against
SCTP state exhaustion denial-of-service 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 & 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 &
DTLS (like limiting the number of new TLS or DTLS session 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, the rate at which IPFIX Messages will be accepted
by the Collecting Process, and adaptively limiting the amount of
state kept, particularly records waiting on Templates. These rate
and state limits MAY be provided by a Collecting Process; 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. PR-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, implying that some
forensics may be left.
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 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 [RFC1948], [RFC4960]); 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,
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, it is outside the scope of this
document.
12. IANA Considerations
IPFIX Messages use two fields with assigned values. These are the
IPFIX Version Number, indicating which version of the IPFIX 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 IPFIX Version Number value of 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 Option 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 Version Number or IPFIX Set ID
assignments require a Standards Action [RFC2434], 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 and a Data Set (which contains 2 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 IETF-Specified Information Elements
We want to report the following Information Elements:
- The IPv4 source IP address: sourceIPv4Address in [RFC5102],
with a length of 4 octets
- The IPv4 destination IP address: destinationIPv4Address in
[RFC5102], with a length of 4 octets
- The next-hop IP address (IPv4): ipNextHopIPv4Address in
[RFC5102], with a length of 4 octets
- The number of packets of the Flow: inPacketDeltaCount in
[RFC5102], with a length of 4 octets
- The number of octets of the Flow: inOctetDeltaCount in
[RFC5102], 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| inPacketDeltaCount = 2 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inOctetDeltaCount = 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 [RFC5102], with a
length of 4 octets
- The IPv4 destination IP address: destinationIPv4Address in
[RFC5102], with a length of 4 octets
- An enterprise-specific Information Element representing proprietary
information, with a type of 15 and a length of 4
- The number of packets of the Flow: inPacketDeltaCount in [RFC5102],
with a length of 4 octets
- The number of octets of the Flow: inOctetDeltaCount in [RFC5102],
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. = 15| Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inPacketDeltaCount = 2 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inOctetDeltaCount = 1 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A.3. Data Set Example
In this example, we report the following three Flow Records:
Src IP addr. | Dst IP 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 IETF-Specified 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: exportedPacketCount [RFC5102], with
a length of 2 octets
- Total number of exported Flows: exportedFlowCount [RFC5102], with a
length of 2 octets
The line card, which is represented by the lineCardId Information
Element [RFC5102], 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| exportedPacketCount = 41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |0| exportedFlowCount = 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: exportedPacketCount [RFC5102],
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 [RFC5102], 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| exportedPacketCount = 41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |1|Information Element 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 A.4.1:
- Total number of IPFIX Messages: exportedPacketCount [RFC5102],
with a length of 2 octets
- Total number of exported Flows: exportedFlowCount [RFC5102],
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. = 123 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 | Enterprise Number ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... Enterprise Number |0| exportedPacketCount = 41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |0| exportedFlowCount = 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:
Line Card ID | IPFIX Message | Exported Flow Records
-------------------------------------------------------------------
Line Card 1 (lineCardId=1) | 345 | 10201
Line Card 2 (lineCardId=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 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 Information Element |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A.5.2. Example of Variable-Length Information Element with Length 255
to 65535 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 255 | 1000 | IE ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1000 octet Information Element |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... IE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
References
Normative References
[RFC1305] Mills, D., "Network Time Protocol (Version 3)
Specification, Implementation and Analysis", RFC
1305, March 1992.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing
an IANA Considerations Section in RFCs", BCP 26, RFC
2434, October 1998.
[RFC3280] Housley, R., Polk, W., Ford, W., and D. Solo,
"Internet X.509 Public Key Infrastructure Certificate
and Certificate Revocation List (CRL) Profile", RFC
3280, April 2002.
[RFC3436] Jungmaier, A., Rescorla, E., and M. Tuexen,
"Transport Layer Security over Stream Control
Transmission Protocol", RFC 3436, December 2002.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758, May 2004.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer
Security (TLS) Protocol Version 1.1", RFC 4346, April
2006.
[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport
Layer Security", RFC 4347, April 2006.
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications
(IDNA)", RFC 3490, March 2003.
[RFC3492] Costello, A., "Punycode: A Bootstring encoding of
Unicode for Internationalized Domain Names in
Applications (IDNA)", RFC 3492, March 2003.
[RFC4960] Stewart, R., Ed., "Stream Control Transmission
Protocol", RFC 4960, September 2007.
[RFC5102] Quittek, J., Bryant S., Claise, B., Aitken, P., and
J. Meyer, "Information Model for IP Flow Information
Export", RFC 5102, January 2008.
[TCP] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, September 1981.
[UDP] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
August 1980.
Informative References
[IPFIX-ARCH] Sadasivan, G., Brownlee, N., Claise, B., and J.
Quittek, "Architecture Model for IP Flow Information
Export", Work in Progress, September 2006.
[IPFIX-AS] Zseby, T., Boschi, E., Brownlee, N., and B. Claise,
"IPFIX Applicability", Work in Progress, June 2007.
[PEN] IANA Private Enterprise Numbers registry
http://www.iana.org/assignments/enterprise-numbers.
[RFC1948] Bellovin, S., "Defending Against Sequence Number
Attacks", RFC 1948, May 1996.
[RFC2579] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
"Textual Conventions for SMIv2", STD 58, RFC 2579,
April 1999.
[RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander,
"Requirements for IP Flow Information Export
(IPFIX)", RFC 3917, October 2004.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3954] Claise, B., Ed., "Cisco Systems NetFlow Services
Export Version 9", RFC 3954, October 2004.
[IEEE.754.1985] Institute of Electrical and Electronics Engineers,
"Standard for Binary Floating-Point Arithmetic", IEEE
Standard 754, August 1985.
[dtls-for-sctp] Tuexen, M. and E. Rescola, "Datagram Transport Layer
Security for Stream Control Transmission Protocol",
Work in Progress, November 2007.
Acknowledgments
We would like to thank the following persons: Ganesh Sadasivan for
his significant contribution during the initial phases of the
protocol specification; Juergen Quittek for the coordination job
within IPFIX and PSAMP; Nevil Brownlee, Dave Plonka, Paul Aitken, 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, and many more, for the technical reviews and feedback.
Authors' Addresses
Benoit Claise
Cisco Systems
De Kleetlaan 6a b1
1831 Diegem
Belgium
Phone: +32 2 704 5622
EMail: bclaise@cisco.com
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
CH-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
Brian H. Trammell
CERT Network Situational Awareness
Software Engineering Institute
4500 Fifth Avenue
Pittsburgh, PA 15213
United States
Phone: +1 412 268 9748
EMail: bht@cert.org
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