IPFIX working group
Internet Draft EDITORS: B. Claise
draft-ietf-ipfix-protocol-3.txt Cisco Systems
Expires: July 2004 Mark Fullmer
OARnet
Paul Calato
Riverstone Networks
Reinaldo Penno
Nortel Networks
January 2003
IPFIX Protocol Specifications
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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Abstract
This document specifies the IPFIX protocol that provides network
operators with access to IP flow information. In order to export
IP flow information to the IPFIX collecting process, a common method
of representing the flow data and a standard means of communicating
them from an exporter to a collector required. This document
describes how the IPFIX flow record data, options record data and
control information (templates for example) are carried over a
congestion-aware transport protocol from IPFIX exporting process to
IPFIX collecting process.
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Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
Table of Contents
1. Points of Discussion.........................................3
1.1 Open Issues................................................3
1.2 Action Items...............................................7
2. Introduction.................................................7
2.1 IPFIX Documents Overview...................................7
3. Terminology..................................................8
3.1 Terminology Summary Table.................................13
4. Criteria for Flow Expiration and Export.....................14
4.1 Flow Expiration...........................................14
4.2 Flow Export...............................................14
5. Transport Protocol..........................................15
5.1 Transport Compliance and Transport Usage..................15
5.2 TCP.......................................................15
5.3 SCTP......................................................16
5.3.1 Congestion Avoidance.................................16
5.3.2 Reliability..........................................16
5.3.3 Exporting Process....................................16
5.3.3.1 MTU size............................................16
5.3.3.2 Source ID...........................................17
5.3.3.3 Association.........................................17
5.3.3.4 Stream..............................................17
5.3.3.5 Template............................................18
5.3.4 Collecting Process...................................18
5.3.5 SCTP Partially Reliable..............................19
5.4 UDP.......................................................19
6. Failover....................................................19
6.1 Simple Failover based on the transport protocol...........19
6.2 Something else?...........................................20
7. Message Layout..............................................20
8. IPFIX Message Format........................................21
8.1 Header Format.............................................21
8.2 Field Type Format.........................................22
8.3 Template FlowSet Format...................................24
8.3.1 IETF Exclusive Template FlowSet Format.................24
8.3.2 Vendor Specified Template FlowSet Format...............26
8.4 Data FlowSet Format.......................................27
8.5 Options Template FlowSet Format...........................29
8.5.1 IETF Exclusive Options Template FlowSet Format.........29
8.5.2 Vendor Specified Options Template FlowSet Format.......31
8.5.3 Options Data Record Format.............................32
9. Specific Reporting Requirements.............................34
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9.1 The Metering Process Statistics Option Template...........35
10. Export Packet "Export Time" Computation and Flow Record Time35
10.1 Microsecond Precision....................................35
10.2 Millisecond Precision....................................36
10.3 Nanosecond Precision.....................................37
10.4 Multiple Precisions......................................37
11. Linkage with the Information Model.........................37
11.1 Boolean..................................................37
11.2 Byte.....................................................37
11.3 UnsignedByte.............................................38
11.4 Short....................................................38
11.5 Reduced Size Encoding of Integral Types..................38
12. Variable Length Data Type..................................39
13. Template Management........................................40
14. The Collecting Process's Side..............................41
15. Security Considerations....................................43
15.1 IPsec Usage..............................................43
15.1.1 Selectors............................................43
15.1.2 Mode.................................................44
15.1.3 Key Management.......................................44
15.1.4 Security Policy......................................44
15.1.5 Authentication.......................................44
15.1.6 Availability.........................................44
15.2 TLS Usage................................................45
15.3 Protection against DoS attacks...........................45
15.4 When IPsec or TLS is not an option.......................45
15.5 Logging an IPFIX Attack..................................46
16. IANA Considerations........................................46
17. Examples...................................................47
17.1 Message Header Example...................................47
17.2 Template FlowSet Example.................................48
17.3 Data FlowSet Example.....................................48
17.4 Options Template FlowSet Example.........................49
17.5 Data FlowSet with Options Data Records Example...........50
18. References.................................................51
18.1 Normative References.....................................51
18.2 Informative References...................................51
19. Acknowledgments............................................52
1.
Points of Discussion
1.1
Open Issues
This section covers the open issues, still to be resolved/updated in
this draft:
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Issues in the Terminology section
PROTO-1: Is flowSet the right term to use?
- leave as is
- Record Set
- Record Array
- Record Collection
- Record List
PROTO-2: Some discrepancies between data types, field type and
Information
Element terminology.
- field type (IPFIX-PROTO) conflicts with field ID (IPFIX-INFO)
- suggestion: use field type instead of field Id in IPFIX-INFO
- rename 'type' to 'data type' and 'info elements' to 'fields'
in IPFIX-INFO
PROTO-3: IP encapsulated packet
- IP Traffic Flow definition speaks of IP packets
- Metering Process definitions say:
Input to the metering process are packets
- We don't want to limit ourselves to IPv4 and IPv6
Issues in the Transport Protocol section
PROTO-4: TCP and UDP are is not yet covered
PROTO-5: Error recovery, for example what to do if a collector
receives a message it can't decode.
Per protocol issue, ie TCP reset the session because it's a
stream protocol and can't recover.
PROTO-6: Section 5.2.3.3, Association: What happens if the Exporter
gets no response
from any Collector?
I think we should specify a (not-too-aggressive) retry
algorithm.
PROTO-7: Dropping data before export: What to do with sequence
numbers?
PROTO-8: Why having a stream per SID?
PROTO-9: IPFIX message should have MTU size.
PROTO-10: How to re-establish a lost connection? Procedure per
transport protocol?
Issues in the Failover section
PROTO-11: (initial version required) Section needs to be written
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If we tackle reliability/failover a state diagram is needed.
Issues in the Message Layout section
PROTO-12: Do we need the IETF exclusive template flowset format?
suggested solution:
- reserve flowset ID 0 & 1 for compatibility with NFv9
- try to make flowset ID 2 & 3 definition fully compatible with
NFv9
- add note that if you implement ID 2/3 correctly, you can also
process ID 0/1.
PROTO-13: How to distinguish IETF field IDs from vendor field IDs
- Specify method for detecting the difference in section 8.
- Add a note that there is a common ID space for for field types
used in data templates and option templates
- (Editorial) make clear that Section 8.2 also applies to option
templates
PROTO-14: Why do we need padding? Should we shift it to MAY?
limit the size of the padding? Yes
solution:
- padding shorter than actual Record Length
- fill with 0
- only at end of flowset
- applies to all flowsets
- padding is OPTIONAL (MAY) , not RECOMMENDED (SHOULD)
Issues in the IPFIX Message Format section
PROTO-15: Remove Reserved 2 octets in Vendor specific option
template flowset and add padding at the end
PROTO-16: relationship between several different scopes in one
record
PROTO-17: redefine scope values?
- 1 System
2 IP interface
3 observation domain (SID) (preciously called line card)
4 reserved (previously used for cache)
5 template
6 metering process?
7 flow recording process?
8 exporting process?
9 observation point?
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PROTO-18: Can we have an optional length of 0 bytes for the scope
section in the option template?
PROTO-19: Do we really need different templates formats for flows
and options?
PROTO-20 Do we really need different record formats for flows and
options?
Issues in the Specific Reporting Requirement section
PROTO-21: Do we need to define some mandatory content of the
metering process statistics option template?
- Maurizio suggested text on the mailing list
PROTO-22: Exporter ID (ie IP address of exporter)
Issues in the Export Packet "Export Time" Computation and Flow
Record Time section
PROTO-23: Finalize the time details
Issues in the Linkage with the Information Model section
PROTO-24: Section 11 "Linkage with the information model" must be
completed with types used in [IPFIX-INFO]
Issues in the Template Management section
PROTO-25: The section 11 "Template Management" will have to updated
according to the transport protocol.
- For example, the point 2 of the section "Template Management".
Remark: the template management will vary with TCP, SCTP,
etc...
Must have both sections updated: transport updated and
template management sections (BTW, this is the same for
the failover section).
Issues in the IANA section
PROTO-26: IANA considerations section to be updated: have a look at
RFC 2434, which sets out guidelines for IANA Considerations.
Also, searching the RFCs for 'IANA Considerations' brings
up quite a few RFCs to look at as models.
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Issues - Miscellaneous
PROTO-27: Need an example with the Vendor Specified Information
Element
PROTO-28: Packet Sampling. This is mentioned in both the
Requirements I-D and the AS I-D. We need to decide how it should be
covered in the IPFIX drafts.
1.2
Action Items
This section covers the action items for this draft
PROTO-29: number all the figures
PROTO-30: Review the requirements draft to see what we miss, once
it's an I-RFC
2.
Introduction
A data network with IP traffic, primarily consists of IP Flows
passing through the network elements of the network. It is often
interesting, useful or even a requirement 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 an
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 afore mentioned 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.
2.1
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
processing is defined in [IPFIX-ARCH], per the requirements defined
in [IPFIX-REQ]. [IPFIX-PROTO] specifies how IPFIX flow record data,
options record data and control information is carried via a
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congestion-aware transport protocol from IPFIX exporting process to
IPFIX collecting process. IPFIX has a formal description of IPFIX
information elements (fields), their name, type and additional
semantic information, as specified in [IPFIX-INFO]. 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.
3.
Terminology
The definition of the basic terms like IP Traffic Flow, Exporting
Process, Collecting Process, Observation Points etc. are
semantically identical with that found in the IPFIX requirements
document [IPFIX-REQ]. Some of the terms have been expanded for more
clarity when defining the protocol. Additional terms required for
the protocol has also been defined. For the same terms defined in
both this document and [IPFIX-ARCH], the definitions are identical
with [IPFIX-ARCH].
The terminology summary table in Section 3.1 gives a quick overview
of the relationships between some of the different terms defined.
Observation Point
The Observation Point is a location in the network where IP packets
can be observed. Examples are a line to which a probe is attached,
a shared medium such as an Ethernet-based LAN, a single port of a
router, or a set of interfaces (physical or logical) of a router.
Note that one Observation Point may be a superset of several
other Observation Points. For example one Observation Point can be
an entire line card. This would be the superset of the
individual Observation Points at the line card's interfaces.
Observation Domain
The set of Observation Points, which is the largest aggregatable set
of Flow information at the Metering Process is termed an Observation
Domain. Each Observation Domain presents itself as a unique ID to
the Collecting Process for identifying the IPFIX Messages it
generates.
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For example, a router line card composed of several interfaces with
each interface being an Observation Point. Every Observation Point
is associated with an Observation Domain.
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 one:
A flow is defined as a set of IP packets passing an observation
point in the network during a certain time interval. All packets
belonging to a particular flow have a set of common properties.
Each property is defined as the result of applying a function to the
values of:
1. one or more packet header field (e.g. destination IP address),
transport header field (e.g. destination port number), or
application header field (e.g. RTP header fields [RFC1889])
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 to belong to a flow if it completely satisfies
all the defined properties of the flow.
This definition covers the range from a flow containing all packet
observed at a network interface to a flow consisting of just a
single packet between two applications with a specific sequence
number.
Flow Key
Each of the fields which belong to
1. Packet header (e.g. destination IP address)
2. Property of the packet itself (e.g. packet length)
3. Derived from packet treatment (e.g. AS number)
which is used to define a Flow is termed as Flow Key.
Flow Type
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A function F which would take input as a set of Flow Keys and
produce as output one or more Flows depending on the combination of
values for the set of 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 of all
packets of the Flow) and usually characteristic properties of the
Flow (e.g. source IP address).
Metering Process
The Metering Process generates Flow Records. Input to the process
are packet headers 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.
IPFIX Device
A device hosting at least an Observation Point, a Metering Process
and an Exporting Process. Typically, corresponding Observation
Point(s), Metering Process(es) and Exporting Process(es) are co-
located at this device, for example at a router.
IPFIX Node
An IPFIX node is a host that implements the IPFIX protocol
which means it contains an Exporting Process or a Collecting
Process or both.
Collecting Process
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The Collecting Process receives Flow Records from one or more
Exporting Processes. The Collecting Process might store received
Flow Records or further process them, but these actions are out of
the scope of this document.
Collector
The device which hosts one or more Collecting Processes.
Flow Recording Process
The Flows generated from the metering device(s) in an Observation
Domain could be collected into one or more database before
exporting. This functional block in addition to maintaining the Flow
database(s) does Flow aggregation, maintain the aggregate statistics
etc.
This block is optional for an IPFIX device.
Template
Template is an ordered n-tuple (e.g. <type,length>, TLV), used to
completely identify the structure and semantics of a particular
information that needs to be communicated from the IPFIX Device to
the Collector. Each template is uniquely identifiable by some means
(e.g. by using a Template ID).
Control Information, Data Stream
The information that needs to be exported from the IPFIX device can
be classified into the following categories:
- Control Information:
This includes the Flow type definition, selection criteria for
packets within the Flow sent by the Exporting Process and any IPFIX
protocol messages (e.g. keepalives). The 'control' stream carries
all the information needed for the end-points to understand the
IPFIX protocol, and specifically for the receiver to understand and
interpret the data sent by the sender.
- Data Stream:
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This includes data records carrying the field values for the various
observed Flows at each of the Observation Point. A sequence of such
records may also be described as a Data Stream.
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 the Collecting Process. An IPFIX Message is
encapsulated within a transport layer header.
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 Flow Data Record.
Flow Data Record
A Flow Data Record is a data record that contains values of the Flow
parameters corresponding to a Template Record.
Options Template Record
An Options Template Record defines the structure and interpretation
of fields in an Options Data Record, including defining how to scope
the applicability of the Options Data Record.
Options Data Record
The Options Data Record is a data record that contains values and
scope information of the Flow measurement parameters, corresponding
to an Options Template Record.
FlowSet
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FlowSet is a generic term for a collection of records that have a
similar structure. In an IPFIX Message, one or more FlowSets follow
the Message Header.
There are three different types of FlowSets: Template FlowSet,
Options Template FlowSet, and Data FlowSet.
Template FlowSet
A Template FlowSet is a collection of one or more Template Records
that have been grouped together in an IPFIX Message.
Options Template FlowSet
An Options Template FlowSet is a collection of one or more Options
Template Records that have been grouped together in an IPFIX
Message.
Data FlowSet
A Data FlowSet is one or more records, of the same type, that are
grouped together in an IPFIX Message. Each record is either a Flow
Data Record or an Options Data Record 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 which may appear in an IPFIX Flow
Record. The IPFIX information model [IPFIX-INFO] 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 determine the valid encoding mechanisms for use in IPFIX.
3.1
Terminology Summary Table
+------------------+---------------------------------------------+
| | Contents |
| +--------------------+------------------------+
| FlowSet | Template Record | Data Record |
+------------------+--------------------+------------------------+
| | | Flow Data Record(s) |
| Data FlowSet | / | or |
| | | Options Data Record(s) |
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+------------------+--------------------+------------------------+
| Template FlowSet | Template Record(s) | / |
+------------------+--------------------+------------------------+
| Options Template | Options Template | / |
| FlowSet | Record(s) | |
+------------------+--------------------+------------------------+
A Data FlowSet is composed of an Options Data Record(s) or Flow Data
Record(s). No Template Record is included. A Template Record defines
the Flow Data Record, and an Options Template Record defines the
Options Data Record.
A Template FlowSet is composed of Template Record(s). No Flow or
Options Data Record is included.
An Options Template FlowSet is composed of Options Template
Record(s). No Flow or Options Data Record is included.
4.
Criteria for Flow Expiration and Export
4.1
Flow Expiration
A Flow is considered as expired under the following conditions:
1. If the Metering Process can detect the end of a Flow. For
example, if the FIN or RST bit is detected in a TCP
[TCP] connection.
2. If no packets belonging to the Flow have been observed for a
certain period of time. This time period SHOULD be configurable at
the Metering Process. Note that if the time period is set to 0, the
Metering Process will create a Flow for every single packet
observed.
3. If the Metering Process experiences internal constraints, a Flow
MAY be expired forcibly. For example, counters wrapping or low
memory.
4.2
Flow Export
A flow can be exported because it expired due to the reasons
mentioned in Flow Expiration section. The exporting process decides
when and whether to export an expired flow. For example: the
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exporting process exports a portion of the expired flows every 'x'
seconds.
For long-lasting Flows, the Exporting Process SHOULD export the Flow
Records on a regular basis or based on some export policy. This
periodicity or export policy SHOULD be configurable at the Metering
Process.
5.
Transport Protocol
The IPFIX Protocol Specifications have been designed to be transport
protocol independent. Note that the Exporter can export to multiple
Collecting Processes, using independent transport protocols.
5.1
Transport Compliance and Transport Usage
We must 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
avoiding mode.
SCTP [RFC2960] MUST be implemented by all compliant implementations.
UDP [UDP] and TCP [TCP] MAY also be implemented by compliant
implementations.
SCTP SHOULD be used in deployments where exporters and collectors
are communicating over links which are susceptible to congestion.
TCP MAY be used in deployments where exporters and collectors
communicate over links which are susceptible to congestion, but SCTP
is preferred, due to its ability to limit back pressure on exporters
(especially when using PR-SCTP [SCTP-PR]) and its message vs. stream
orientation.
Other non-congestion aware protocols (like UDP) MAY be used in
deployments where exporters and collectors always communicate over
dedicated links which are not susceptible to congestion.
5.2
TCP
To be completed.
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TCP [TCP]
5.3
SCTP
This section describes how IPFIX can be transported over SCTP
[RFC2960] using traditional reliable mode.
IPFIX can also be transported over the partial reliable or
unreliable mode [PR-SCTP]. These last 2 modes will be briefly
discussed, while waiting for [PR-SCTP] to become a standard.
5.3.1 Congestion Avoidance
The SCTP transport protocol provides the required level of
congestion avoidance by design.
5.3.2 Reliability
The SCTP transport protocol is by default reliable, but has the
capability to operate in unreliable and partially reliable modes
[PR-SCTP].
Using reliable SCTP streams (referred to hereafter as "streams") for
the IPFIX export is not in itself a guarantee that all records are
delivered. If there is congestion on the link from the exporter to
the collector, or if a significant amount of retransmissions are
needed, the send queues on the Exporting Process may fill up. In
that case it's up to the Exporting Process to decide what to do. It
MAY either halt export (buffer the data until there is space in the
send queues again) or discard IPFIX Messages away instead of
inserting them into the send queue. If any data is not inserted into
the send queues, the sequence numbers used for export must reflect
the loss of data.
5.3.3 Exporting Process
5.3.3.1 MTU size
Each IPFIX Message SHOULD be equal to or less than the local MTU in
size. When an IPFIX Message is transmitted over a network with an
MTU smaller than the local MTU, IP fragmentation may be used.
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5.3.3.2 Source ID
The IPFIX Message MUST contain a Message Header, which includes a
source id (SID). The SID indicates from which Observation Domain the
data is being exported, and should be kept unique for each such
Observation Domain.
If a Metering Process consists of a single Observation Domain, a
single SID value MUST be used for all IPFIX Messages. The Exporting
Process will typically open one association to the collector, but
more are possible, in which one or more streams can be used. The
Exporting Process has the choice of transmitting parts of the export
data in separate streams or all data in one stream.
If a Metering Process consists of multiple Observation Domains, one
SID value for each Observation Domain MUST be used. The Exporting
Process will typically open one association, but more are possible,
in which at least one stream per Observation Domain is used.
The Exporting Process has the choice of using more than one stream
per Observation Domain, but data from multiple Observation Domains
should not be transmitted over the same stream.
5.3.3.3 Association
The Exporting Process MAY create one or more associations
(connection "bundle" in SCTP terminology) to the Collecting Process.
The Collecting Process MAY not initiate the connection. Inside each
association one or more streams MAY be requested by the Exporting
Process. If the Collecting Process can not support the requested
number of streams, it MAY choose to refuse the connection and the
Exporting Process should try to reduce, if possible, the number of
streams needed to perform the export.
5.3.3.4 Stream
An Observation Domain MUST use at least one stream, but MAY use
multiple streams, to export data records. The Observation Domain
MUST use the same SID value for all streams used.
An Exporting Process must not transmit messages with different SID
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values in one stream, the Collecting Process should however verify
that the SID values are the expected values.
5.3.3.5 Template
Since the SCTP association is connection oriented the available
Template Records MUST be transmitted from each Observation Domain to
the Collecting Process immediately after the association is
established.
As a minimum the Template Records MUST be transmitted immediately
after they start to exist on the Metering Process and SHOULD
preferably be transmitted before any data, using the new Template
Record, have been transmitted. The Collecting Process SHOULD however
accept data without a Template Record.
When using a reliable mode for Template Record export, or if the
exporter knows that the IPFIX Message containing the templates was
positively acknowledged by the SCTP layer, it is not necessary to
periodically export the Template Records.
5.3.4 Collecting Process
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. If the Collecting Process
doesn't support the number of streams inside the association, the
Collecting Process MUST refuse the connection and continue listen
for a new request.
When data is received from an association, the Collecting Process
MUST correlate data, with the same SID (Source ID) value, from
multiple streams into one export Flow from an Observation Domain.
This allows the Observation Domain to use separate streams for
different types of information.
The Collecting Process SHOULD verify that the received IPFIX
Messages inside one stream does not have differing SID values. The
Exporting Process MUST not transmit messages inside one stream with
multiple SID values. The correlated Flow Records are then treated
like a normal export Flow.
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5.3.5 SCTP Partially Reliable
This mode will not be discussed any further until [PR-SCTP] becomes
a standard, even if this mode offers a few advantages:
freedom to use SCTP as a reliable, single stream transport, as well
as multiple streams with different properties, for example in terms
of reliability, carrying different data types dependant on their
importance for the system.
Unreliable or partial reliability may be chosen for one or more
streams inside an association. Unreliable transport MAY be preferred
where large amount of data is to be exported and keeping send queues
is either an unnecessary overhead or impractical. Partial
reliability MAY be chosen where a small amount of queuing is
possible.
Naturally it is better to send templates over a reliable stream and
send the data on an unreliable (or partial reliable) stream. When an
exporter handles data with different properties it might even be
preferable to send them over different streams according to those
properties.
Example: an Exporting Process can use two streams per Observation
Domain. A reliable stream could be used for exporting templates, to
reduce the likelihood of loss and to remove the need for blind
retransmissions, and a partial or unreliable stream for data, to
avoid buffering of large amounts of data.
5.4
UDP
To be completed.
UDP [UDP]
6.
Failover
When to fail over?
How to fail back?
How to ensure stability of the failover mechanism (prevent
oscillations)?
Does the exporter open connections to all the potential collectors
and keep them primed with template info?
6.1
Simple Failover based on the transport protocol
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In case the transport protocol is connection oriented.
So in case of TCP [TCP] or SCTP [RFC2960].
To be completed.
6.2
Something else?
Potentially based on some application level ACK from the exporter?
7.
Message Layout
An IPFIX Message consists of a Message Header followed by one or
more FlowSets. The FlowSets can be any of the possible three types:
Template, Data, or Options Template.
IPFIX Message:
+--------+-------------------------------------------+
| | +----------+ +---------+ +----------+ |
|Message | | Template | | Data | | Options | |
| Header | | FlowSet | | FlowSet | | Template | ... |
| | | | | | | FlowSet | |
| | +----------+ +---------+ +----------+ |
+--------+-------------------------------------------+
A FlowSet ID is used to distinguish the different types of FlowSets.
FlowSet IDs lower than 256 are reserved for special FlowSets, such
as the Template FlowSet (ID 0) and the Options Template FlowSet (ID
1). The Data FlowSets have a FlowSet ID greater than 255.
The format of the Template, Data, and Options Template FlowSets will
be discussed later in this document. The Exporter MUST code all
binary integers of the Message Header and the different FlowSets 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 FlowSets-A newly created Template is exported as
soon as possible. So if there is already an IPFIX Message with a
Data FlowSet that is being prepared for export, the Template and
Option FlowSets are also interleaved with this information, subject
to availability of space.
IPFIX Message:
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+--------+--------------------------------------------------------+
| | +----------+ +---------+ +-----------+ +---------+ |
|Message | | Template | | Data | | Options | | Data | |
| Header | | FlowSet | | FlowSet | ... | Template | | FlowSet | |
| | | | | | | FlowSet | | | |
| | +----------+ +---------+ +-----------+ +---------+ |
+--------+--------------------------------------------------------+
2. An IPFIX Message consisting entirely of Data FlowSets-After the
appropriate Template Records have been defined and transmitted to
the Collecting Process, the majority of IPFIX Messages consists
solely of Data FlowSets.
IPFIX Message:
+--------+----------------------------------------------+
| | +---------+ +---------+ +---------+ |
|Message | | Data | ... | Data | ... | Data | |
| Header | | FlowSet | ... | FlowSet | ... | FlowSet | |
| | +---------+ +---------+ +---------+ |
+--------+----------------------------------------------+
3. An IPFIX Message consisting entirely of Template and Options
Template FlowSets-The Exporter MAY transmit a message containing
Template and Options Template FlowSets periodically to help ensure
that the Collecting Process has the correct Template Records and
Options Template Records when the corresponding Flow Data records
are received.
IPFIX Message:
+--------+-------------------------------------------------+
| | +----------+ +----------+ +----------+ |
|Message | | Template | | Template | | Options | |
| Header | | FlowSet | ... | FlowSet | ... | Template | |
| | | | | | | FlowSet | |
| | +----------+ +----------+ +----------+ |
+--------+-------------------------------------------------+
8.
IPFIX Message Format
8.1
Header Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version Number | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Export Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
Length
Total Length is the length of the IPFIX message, measured in
octets, including message Header and FlowSet(s).
Export Time
Time in seconds since 0000 UTC 1970, at which the Export
Packet leaves the Exporter.
Sequence Number
Incremental sequence counter of all IPFIX Messages sent from
the current Observation Domain by the Exporting Process.
This value MUST SHOULD be used by the Collecting Process to
identify whether any IPFIX Messages have been missed.
Source ID
A 32-bit value that identifies the Exporter Process
Observation Domain. Collecting Process SHOULD use the
combination of the source IP address and the Source ID field
to separate different export streams originating from the
same Exporting Process.
8.2
Field Type Format
This section describes the Field Type format for both IETF specified
Information Elements [IPFIX-INFO] and Vendor Specified Information
Elements. Vendors need the ability to define proprietary Information
Claise, et. al Standard Track [Page 22]
IPFIX Protocol Specifications February 2004
Elements, because, for example, they are delivering pre-standards
product, or the Information Element is in some way commercially
sensitive.
The Field Ids used to identify Information Elements are divided into
two non-overlapping ranges: the IETF specified range and the vendor
specified range. This partitioning of the identifiers into two
ranges allows the Collecting Process to discriminate between an IETF
specified Information Element and a Vendor Specified Information
Element. The vendor specified range is shared by all vendors, and
thus needs an accompanying vendor identifier to uniquely identify
it.
The format of an IETF defined Field Type is shown in Fig A.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type | Field Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fig A: IETF defined Field Type
Where:
Field Type
A numeric value that represents the type of the field. Refer
to [IPFIX-INFO].
Field Length
The length of the corresponding Field Type, in bytes. Refer
to [IPFIX-INFO].
The format of the Vendor Specified Field Type is shown in Fig B.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type | Field Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Fig B: Vendor Specified Field Type
Where:
Field Type
A numeric value that represents the type of the field. Refer
to [IPFIX-INFO].
Field Length
The length of the corresponding Field Type, in bytes. Refer
to [IPFIX-INFO].
Enterprise Number
IANA enterprise number [PEN] of the authority defining the
field type in this template record.
8.3
Template FlowSet Format
One of the essential elements in the IPFIX format is the Template
FlowSet. Templates greatly enhance the flexibility of the Flow
Record format because they allow the Collecting Process to process
Flow Records without necessarily knowing the interpretation of all
the data in the Flow Record.
8.3.1 IETF Exclusive Template FlowSet Format
The IETF exclusive Template FlowSet MAY be used when the template
contains only IETF defined Information Elements. This format is
provided for backwards compatibility [NETFLOW9]. The format of the
IETF exclusive Template FlowSet is shown in Figure C.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 0 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 1 | Field Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 1 | Field Length 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 2 | Field Length 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type N | Field Length N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 2 | Field Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 1 | Field Length 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 2 | Field Length 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type M | Field Length M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID K | Field Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure C: IETF Exclusive Template FlowSet Format
Field Descriptions
FlowSet ID
FlowSet ID value of 0 is reserved for the Template FlowSet.
Length
Total length of this FlowSet. Because an individual Template
FlowSet MAY contain multiple Template Records, the Length
value MUST be used to determine the position of the next
FlowSet record, which could be any type of FlowSet. Length
is the sum of the lengths of the FlowSet ID, the Length
itself, and all Template Records within this FlowSet.
Template ID
Each of the newly generated Template Records is given a
unique Template ID. This uniqueness is local to the
Observation Domain that generated the Template ID.
Template IDs 0-255 are reserved for Template FlowSets,
Options FlowSets, and other reserved FlowSets yet to be
created. Template IDs of Data FlowSets are numbered from 256
to 65535.
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Field Count
Number of fields in this Template Record. Because a Template
FlowSet usually contains multiple Template Records, this
field allows the Collecting Process to determine the end of
the current Template Record and the start of the next.
Field Type
A numeric value that represents the type of the field. Refer
to [IPFIX-INFO].
Field Length
The length of the corresponding Field Type, in bytes. Refer
to [IPFIX-INFO].
8.3.2 Vendor Specified Template FlowSet Format
A vendor specified Template FlowSet MUST be used when the template
contains one or more Vendor Specified Information Elements. A vendor
specified template MAY exclusively contain IETF defined Field Types.
A vendor specified template MAY contain Vendor Specified Information
Elements from multiple vendors.
The format of the Vendor Specified Template FlowSet is shown in
Figure D.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 1 | Field Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 1 | Field Length 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number 1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 2 | Field Length 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type N | Field Length N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Enterprise Number 1.N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 2 | Field Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 1 | Field Length 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type 2 | Field Length 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number 2.2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Type M | Field Length M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise Number 2.M |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure D: Vendor Specified Template Flowset
The definition of the fields in the Vendor Specified Template
FlowSet is identical to those described in the IETF exclusive
Template FlowSet Format Field Descriptions except:
FlowSet ID
FlowSet ID value of 2 is reserved for the Vendor Specified
Template FlowSet
Enterprise Number
IANA enterprise number [PEN] of the authority defining the
field type in this template record.
8.4
Data FlowSet Format
The format of the Data FlowSet 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = Template ID | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 1 - Field Value 1 | Record 1 - Field Value 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 1 - Field Value 3 | ... |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 2 - Field Value 1 | Record 2 - Field Value 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 2 - Field Value 3 | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 3 - Field Value 1 | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note that not all Field Values do necessarily have a length of 16
bit.
Data FlowSet Field Descriptions
FlowSet ID = Template ID
Each Data FlowSet is associated with a FlowSet ID. The
FlowSet ID maps to a (previously generated) Template ID. The
Collecting Process MUST use the FlowSet ID to find the
corresponding Template Record and decode the Flow Records
from the FlowSet.
Length
The length of this FlowSet.
Length is the sum total of lengths of FlowSet ID, Length
itself, all Flow Records within this FlowSet, and the
padding bytes, if any.
Record N - Field Value M
The remainder of the Data FlowSet is a collection of Flow
Data Record(s), each containing a set of field types and
values. The Type and Length of the fields have been
previously defined in the Template Record referenced by the
FlowSet ID or Template ID.
Padding
The Exporting Process SHOULD insert some padding bytes so
that the subsequent FlowSet starts at a 4-byte aligned
boundary. It is important to note that the Length field
includes the padding bits.
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Interpretation of the Data FlowSet format can be done only if the
Template FlowSet corresponding to the Template ID is available at
the Collecting Process.
8.5
Options Template FlowSet Format
The Options Template Record (and its corresponding Options Data
Record) is used to supply information about the Metering Process
configuration or Metering Process specific data, rather than
supplying information about IP Flows.
For example, the Options Template FlowSet can report the sample rate
of a specific interface, if sampling is supported, along with the
sampling method used.
8.5.1 IETF Exclusive Options Template FlowSet Format
The IETF exclusive Options Template FlowSet Format MAY be used
when the template contains only IETF defined options. This format
is provided for backwards compatibility [NETFLOW9]. The format of
the IETF exclusive Options Template FlowSet Format is shown in
Figure E.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 1 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID | Option Scope Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Length | Scope 1 Field Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope N Field Length | Option 1 Field Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option 1 Field Length | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option M Field Length | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure E: IETF Exclusive Options Template FlowSet
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IPFIX Protocol Specifications February 2004
The IETF Exclusive Options Template FlowSet Field Definitions are
as follows:
FlowSet ID = 1
A FlowSet ID value of 1 is reserved for the Options
Template.
Length
Total length of this FlowSet. Each Options Template FlowSet
MAY contain multiple Options Template Records. Thus, the
Length value MUST be used to determine the position of the
next FlowSet record, which could be either a Template
FlowSet or Data FlowSet.
Length is the sum total of lengths of FlowSet ID, the Length
itself, and all Options Template Records within this FlowSet
Template ID.
Template ID
Template ID of this Options Template. This value is greater
than 255.
Option Scope Length
The length in bytes of any Scope fields definition contained
in the Options Template Record (The use of "Scope" is
described below).
Option Length
The length (in bytes) of any options field definitions
contained in this Options Template Record.
Scope 1 Field Type
The relevant portion of the Exporting Process/Metering
Process to which the Options Data Record refers.
Currently defined values are:
1 System
2 Interface
3 Line Card
4 Cache
5 Template
For example, the Metering Process can be implemented on a
per-interface basis, so if the Options Template Record were
reporting on how the Metering Process is configured, the
Scope for the report would be 2 (interface). The associated
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interface ID would then be carried in the associated Options
Data FlowSet. The Scope can be limited further by listing
multiple scopes that all must match at the same time. Note
that the Scope fields always precede the Option fields.
Scope 1 Field Length
The length (in bytes) of the Scope field, as it would appear
in an Options Data Record.
Option 1 Field Type
A numeric value that represents the type of field that would
appear in the Options Template Record. Refer to [IPFIX-
INFO].
Option 1 Field Length
The length (in bytes) of the Option Field.
Padding
The Exporting Process SHOULD insert some padding bytes so
that the subsequent FlowSet starts at a 4-byte aligned
boundary. It is important to note that the Length field
includes the padding bits.
8.5.2 Vendor Specified Options Template FlowSet Format
A vendor specified Options Template MUST be used when the template
contains one or more vendor specified options. A vendor specified
Options Template MAY exclusively contain IETF defined Field Types. A
vendor specified template MAY contain Vendor Specified Information
Elements from multiple vendors.
The format of the Vendor Specified Options Template FlowSet is shown
in Figure E.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 3 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID | Option Scope Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Length | Reserved must be zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Scope 1 Field Type | Scope 1 Field Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope N Field Type | Scope N Field Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope N Enterprise Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option 1 Field Type | Option 1 Field Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option 1 Enterprise Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option N Field Type | Option N Field Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure E: Vendor Specified Option Template FlowSet
The definition of the fields in the vendor specified Options
Template FlowSet is identical to those described IETF Exclusive
Options Template FlowSet Format Field Descriptions except:
FlowSet ID = 3
A FlowSet ID value of 3 is reserved for a VI Qualified
Options Template.
Scope N Enterprise Number
IANA enterprise number [PEN] of the authority defining
Scope N.
Option N Enterprise Number
IANA enterprise number [PEN] of the authority defining the
Option N field type.
8.5.3 Options Data Record Format
The Options Data Records are sent in Data FlowSets, on a regular
basis, but not with every Flow Data Record. How frequently these
Options Data Records are exported is configurable. See the Templates
Management" section for more details.
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The format of the Data FlowSet containing Options Data Records
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = Template ID | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 1 - Scope 1 Value | Record 1 - Scope 2 Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |Record 1 - Option Field 1 Value|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Record 1 - Option Field 2 Value| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 2 - Scope 1 Value | Record 2 - Scope 2 Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |Record 2 - Option Field 1 Value|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Record 2 - Option Field 2 Value| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Record 3 - Scope 1 Value | Record 3 - Scope 2 Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |Record 3 - Option Field 1 Value|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Record 3 - Option Field 2 Value| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Options Data Records of the Data FlowSet Field Descriptions
FlowSet ID = Template ID
A FlowSet ID precedes each group of Options Data Records
within a Data FlowSet. The FlowSet ID maps to a previously
generated Template ID corresponding to this Options Template
Record. The Collecting Process MUST use the FlowSet ID to
map the appropriate type and length to any field values that
follow.
Length
The length of this FlowSet.
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IPFIX Protocol Specifications February 2004
Length is the sum of the lengths of the FlowSet ID, Length
itself, all the Options Data Records within this FlowSet,
and the padding bytes, if any.
Record N - Option Field M Value
The remainder of the Data FlowSet is a collection of Flow
Records, each containing a set of scope and field values.
The type and length of the fields were previously defined in
the Options Template Record referenced by the FlowSet ID or
Template ID.
Padding
The Exporting Process SHOULD insert some padding bytes so
that the subsequent FlowSet starts at a 4-byte aligned
boundary. It is important to note that the Length field
includes the padding bits.
The Data FlowSet format can be interpreted only if the Options
Template FlowSet corresponding to the Template ID is available at
the Collecting Process.
9.
Specific Reporting Requirements
Some specific Options Templates and Options Templates Records are
necessary to provide extra information about the Flow Records and
about the Metering Process.
The ipfixOption [IPFIX-INFO], always included in these specific
Options Templates, defines the type of information sent in the Option
Template / Option Template Record pair. For example, if the
ipfixOption [IPFIX-INFO] value is METER_STATS, then the Option
Template will specify information about the Metering Process
statistics. The ipfixOption [IPFIX-INFO] MUST always be the first Data
Type in the Option Template so that the Collector could quickly
determine whether or not a specific Option Template is described. And
if the ipfixOption [IPFIX-INFO] is present, which specific Option
Template type it defines.
The minimum set of Data Types is always specified in these Specific
IPFIX Options Templates. Nevertheless, extra Data Types MAY be used in
these specific Options Templates.
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9.1
The Metering Process Statistics Option Template
The Metering Process Statistics Option Template defines the Metering
Process Statistics with the export of the following Data Types [IPFIX-
INFO]:
ipfixOption The value MUST be METER_STATS
observationDomain Source ID
lostFlows flows not exported due to resource
starvation
lostFlowsPacket Packets in the lost flows
lostFlowsBytes Bytes in the lost flows
droppedPacketCount Packets dropped by Metering Process
at the Observation Point
droppedByteCount Bytes dropped by Metering Process at the
Observation Domain
time; When this record was generated
The minimum set of Data Type in the Metering Process Statistics Option
Template is: ipfixOption, observationDomain, lostFlows, time
10.
Export Packet "Export Time" Computation and Flow Record Time
10.1
Microsecond Precision
For a Data FlowSet with Flow Records requiring microsecond
precision, the Export Packet "Export Time" field MUST be calculated
so that each Flow Records flowStartUsec [IPFIX-INFO] and flowEndUsec
[IPFIX-INFO] would contain a 32 bit signed microsecond offset from
the "Export Time" base timestamp. Hereafter some pseudo code to
calculate the Export Time in one pass, which would return an
absolute duration of 35 minutes for all Flow Records contained in
the Data FlowSet. Flow Records MUST be exported in different Export
Packet if the absolute duration can not fit in those 35 minutes.
// pseudo code for microsecond offset in IPFIX encoded Flow Records.
//
struct flow{
uint32 tv_sec;
uint32 tv_usec;
uint32 numbytes;
... // other information elements...
};
struct flow flowtable [MAX_TABLE_SIZE];
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IPFIX Protocol Specifications February 2004
int lastflowindex = -1;
writeflows() {
if (lastflowindex < 0) return;
// simply take the second field from the first available flow
// and make this the base time for this collection of flows.
uint32 base_sec = flowtable[0].tv_sec;
writeheaderToSocket(base_sec); // put 32-bit second value in header
for (int i=0; i<=lastflowindex; i++){
int32 offset = (flowtable[i].tv_sec - base_sec) * 1000000 +
flowtable[i].tv_usec;
writeint32ToSocket(offset); // put the 32-bit time offset in the
record.
// write other information elements...
}
}
A two pass approach calculation for the optimum (center) "Export
Time" base timestamp would allow an absolute duration of 71 minutes
for all Flow Records contained in the Data FlowSet. The two pass
approach MAY be used.
The "Export Time" base timestamp calculation requires that at the
Export Packet exporting time the Exporting Process MUST run down the
list of Flow Records in the Data FlowSet message and adjust the Flow
start and Flow end timestamps.
10.2
Millisecond Precision
For a Data FlowSet with Flow Records requiring a millisecond
precision, the same principles as in section 10.1 "Microsecond
Precision" will be used.
The only difference will be that the Flow start and the Flow end
SHOULD now be represented respectively by the flowStartMsec [IPFIX-
INFO] and flowEndMsec [IPFIX-INFO]. As a consequence of the
millisecond precision, the absolute duration of all Flow Records is
now of about 49 days. The Export Header "Export Time" base time
SHOULD be calculated with the algorithm described in the Section
10.1 "Microsecond Precision". In order to reduce the load on the
Exporter, the Export Header "Export Time" MAY be the time in seconds
since 0000 UTC 1970 at which the Export Packet leaves the Exporter
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and not the calculated optimum value anymore as described in section
10.1 "Microsecond Precision".
Alternatively, for a Data FlowSet with Flow Records requiring a
millisecond precision, the microsecond mechanism as described in
section 10.1 MAY be used as such. The Flow Record MAY use the
flowStartUsec [IPFIX-INFO] and flowEndUsec [IPFIX-INFO] rounded at a
millisecond precision.
10.3
Nanosecond Precision
For a Data FlowSet with Flow Records requiring a nanosecond
precision, all Flow Records will contain Flow start flowStartNsec
[IPFIX-INFO] and flowEndNsec [IPFIX-INFO]. The Export Header "Export
Time" will be of no use on the Collector side in this case as
the flowStartNsec [IPFIX-INFO] and flowEndNsec [IPFIX-INFO] both
have a nanosecond precision already. Both flowStartNsec [IPFIX-INFO]
and flowEndNsec [IPFIX-INFO] use the NTP time format which is
represented as a 64-bit value which contains a 32-bit specification
of seconds since 1900 and a 32-bit "fraction" field. Refer to the
NTP specification, RFC1305, section 3.1 "Data Formats".
10.4
Multiple Precisions
When Flow Records requiring different precisions must be exported,
the Exporting Process SHOULD split the Flow Records in different
Data FlowSet according to the precision: millisecond, microsecond
or nanosecond.
11.
Linkage with the Information Model
The information model associates each IPFIX Data Type with a well
defined type, such as hexBinary, long, unsignedInt, etc.
This document defines how fields of a given type are encoded.
11.1
Boolean
A boolean field shall be encoded in a single byte with the value of
0 indicating false and any other value indicating true.
11.2
Byte
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A byte value shall be encoded as a single byte representing a value
between -128 and 127. The value is represented in two's complement
notation.
11.3
UnsignedByte
An unsigned byte value shall be encoded as a single byte
representing a value between 0 and 255.
11.4
Short
A short is a 16-bit datum that encodes an integer in the range [-
32768,32767]. The short is represented in two's complement
notation. The most and least significant bytes are 0 and 1,
respectively
EDITOR NOTE: this section 11 must be completed with types used in
[IPFIX-INFO].
11.5
Reduced Size Encoding of Integral Types
Information Elements containing integral types in the information
model MAY be encoded using fewer bytes than those implied by their
type in the information model definition [IPFIX-INFO], based on the
assumption that the smaller type 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 model Data Types definition [IPFIX-INFO] will always
define the maximum encoding size for each Data Type.
For instance the information model [IPFIX-INFO] defines byteCount as
an unsignedLong 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
unsignedInt. For example, a core router would require an
unsignedLong byteCount while an unsignedInt might be sufficient for
an access router.
This behavior is indicated by the Exporter by specifying a type size
smaller than that associated with the assigned type of the field. In
the example above the Exporter would place a length of 4 vs. 8 in
the template.
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Reduced sizing MAY only be applied to the following integral types:
short, unsignedShort, int, unsignedInt, long, unsignedLong. In each
case the downcasting must be to a smaller integral type which MUST
have the same signed vs. unsigned properties.
Specifically unsignedLong may be downcast to unsignedInt,
unsignedShort or unsignedByte. A long may be downcast to an int a
short or a byte. The other downcasts follow the same pattern.
12.
Variable Length Data Type
The IPFIX template mechanism is optimized for fixed length
Information Elements [IPFIX-INFO]. Where an Information Element has
a variable length the following mechanism MUST used to carry the
length information.
In the Template FlowSet the 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
itself.
In most cases the length of the Information Element will be less
than 256 bytes. The following length encoding mechanism optimizes
the overhead of carrying the Information Element length in this
majority case.
If the length of the Information Element is less than 255 bytes, the
length is carried in the first byte of the Information Element. This
is shown on Figure A.
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 A: Variable Length Information Element (length < 255 bytes)
If the length of the Information Element is greater or equal than
256 bytes, the first byte of the Information Element is 255, and the
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length is carried in the second and third bytes of the Information
Element. This is shown in Figure B.
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 (256 to 65535) | IE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... continuing as needed |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure B: Variable Length Information Element
(length 256 to 65535) bytes
13.
Template Management
Flow Data records that correspond to a Template Record MAY appear in
the same and/or subsequent IPFIX Messages. The Template Record is
not necessarily carried in every IPFIX Message. As such, the
Collecting Process MUST store the Template Record to interpret the
corresponding Flow Data Records that are received in subsequent data
messages.
A Collecting Process that receives IPFIX Messages from several
Observation Domains from the same Exporter MUST be aware that the
uniqueness of the Template ID is not guaranteed across Observation
Domains.
The Template IDs must remain constant for the life of the Metering
Process and the Exporting Process. If the Exporting Process or the
Metering Process restarts for any reason, all information about
Templates will be lost and new Template IDs will be created.
Template IDs are thus not guaranteed to be consistent across an
Exporting Process or Metering Process restart.
A newly created Template record is assigned an unused Template ID
from the Exporter. If the template configuration is changed, the
current Template ID is abandoned and SHOULD NOT be reused until the
Metering Process. If a Collecting Process should receive a new
definition for an already existing Template ID, it MUST discard the
previous template definition and use the new one.
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If a configured Template Record on the Exporting Process is deleted,
and re-configured with exactly the same parameters, the same
Template ID COULD be reused.
The Exporting Process sends the Template FlowSet and Options
Template FlowSet under the following conditions:
1. After a Metering Process restarts, the Exporting Process MUST
NOT send any Data FlowSet without sending the corresponding
Template FlowSet and the required Options Template FlowSet in a
previous message or including it in the same IPFIX Message. It
MAY transmit the Template FlowSet and Options Template FlowSet,
without any Data FlowSets, in advance to help ensure that the
Collector will have the correct Template Record before receiving
the first Flow or Options Data Record.
2. In the event of configuration changes, the Exporting Process
SHOULD send the new template definitions at an accelerated rate.
In such a case, it MAY 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.
3. On a regular basis, the Exporting Process MUST send all the
Template Records and Options Template Records to refresh the
Collecting Process. Template IDs have a limited lifetime at the
Collecting Process and MUST be periodically refreshed.
Two approaches are taken to make sure that Templates get
refreshed at the Collecting Process:
* Every N number of IPFIX Messages.
* On a time basis, so every N number of minutes.
Both options MUST be configurable by the user on the Exporting
Porcess.
When one of these expiry conditions is met, the Exporting
Process MUST send the Template FlowSet and Options Template.
14.
The Collecting Process's Side
The Collecting Process receives Template Records from the Exporting
Process, normally before receiving Flow Data Records (or Options
Data Records). The Flow Data Records (or Options Data Records) can
then be decoded and stored locally on the devices. If the Template
Records have not been received at the time Flow Data Records (or
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Options Data Records) are received, the Collecting Process SHOULD
store the Flow Data Records (or Options Data Records) and decode
them after the Template Records are received. A Collecting Process
device MUST NOT assume that the Data FlowSet and the associated
Template FlowSet (or Options Template FlowSet) are exported in the
same IPFIX Message.
The Collecting Process MUST NOT assume that one and only one
Template FlowSet is present in an IPFIX Message.
The life of a template at the Collecting Process is limited to a
fixed refresh timeout. Templates not refreshed from the Exporting
Process within the timeout are expired at the Collecting Process.
The Collecting Process MUST NOT attempt to decode the Flow or
Options Data Records with an expired Template. At any given time the
Collecting Process SHOULD maintain the following for all the current
Template Records and Options Template Records: <Exporting Process,
Observation Domain, Template ID, Template Definition, Last Received>
Note that the Observation Domain is identified by the Source ID
field from the IPFIX Message.
Template IDs are unique per Exporting Process and per Observation
Domain.
If the Collecting Process receives a new Template Record (for
example, in the case of an Exporter restart) it MUST immediately
override the existing Template Record.
The Collecting Process MUST note the Field ID of any Information
Element that it does not understand and MAY discard the Information
Element from the Flow Record. The Collecting Process MUST note the
size and position of any Vendor Specified Information Element that
it does not understand and discard the Information Element from the
Flow Record.
The Collector MUST accept padding in the Data FlowSet and Options
Template FlowSet, which means for the Flow Data Records, the Options
Data Records and the Template Records.
Refer to the terminology summary table in Section 3.1.
The IPFIX protocol has a sequence number field in the Export Header
which increases with each IPFIX message. A Collector may detect out
of sequence, dropped, or duplicate messages by tracking the sequence
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number. A collector SHOULD provide a logging mechanism for tracking
out of sequence messages. Such out of sequence messages may be due
to congestion on the network link between the Exporter and
Collector, Collector resource exhaustion where it can not process
the IPFIX messages at their arrival rate, Exporter resource
exhaustion where it can not transmit messages at their creation
rate, out of order packet reception, duplicate packet reception, an
Exporting Process reset, or an attacker injecting false messages.
15.
Security Considerations
Because IPFIX can be used to collect billing information and network
forensics, confusing or blinding IPFIX must be seen as a prime
objective during a sophisticated network attack.
If an attacker is in a position to inject false messages into an
IPFIX message stream this will allow them to send forged flow
records, options, or templates. Forged templates may impair the
Collectors ability to process any further Flow Records. Forged Flow
Records would have a direct effect on the application using the
Flows, for example a billing system may generate incorrect billing
information. Forged options may be able to alter the meaning of flow
records, for example if the sample rate is changed.
The IPFIX messages themselves may contain information of value to an
attacker, and thus care must be taken to confine their visibility to
authorized users.
IPFIX messages can be secured using IPsec. Alternatively if IPFIX
runs on top of SCTP or TCP TLS [TLS] can be used.
15.1
IPsec Usage
To secure messages between the Exporter and the Collector an IPFIX
implementation MAY use IPsec. To ensure interworking between
Exporters and Collectors from different vendors, the following IPsec
profile MUST be supported. This profile is derived from [USEIPSEC].
15.1.1 Selectors
IPFIX runs between manually configured pairs of hosts on the
following transport ports (TBD). The appropriate selector would be
Exporter-Collector pairs and port number.
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Note that, if the Exporter is a router, a non-interface ("loopback")
address should be used.
15.1.2 Mode
IPsec MUST be run in transport mode. The AH and ESP MUST be
supported by an IPFIX implementation of IPsec.
The Authentication Header (AH) [RFC2402] MUST be used if
authentication is required. The Security Protocol (ESP) [RFC2406]
must be used if the is a threat to the IPFIX message content, or if
it is confidential.
Normally in situations where the ESP was required the AH would also
be required. If ESP only is used, the sender's IP address MUST be
checked against the IP address asserted in the key management
exchange.
15.1.3 Key Management
In many networks, manual key management will be sufficient, and this
reduces the complexity of the Exporter, albeit at a cost of greater
configuration complexity. Manual key management MUST be supported.
If a replay attack is considered likely, an automated key management
the IKE [IKE] key management system SHOULD be used.
15.1.4 Security Policy
Connections should be accepted only from the designated peer.
15.1.5 Authentication
Given the number of IPFIX capable Exporters that are likely to be
deployed by large ISPs, there will be circumstances where shared key
mechanisms are not adequate. Where an automated key management
system is used, certificate-based IKE SHOULD be supported.
15.1.6 Availability
It is accepted that IPsec will not be universally available in IPFIX
Exporters, and that where it is available, there may be issues of
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throughput, which may itself raise security issues. In such
circumstances the other security measures described in this draft
provide some threat mitigation.
15.2
TLS Usage
The IPFIX Exporter initiating a connection acts as a TLS client
according to [TLS], and an IPFIX Collector that accepts a connection
acts as a TLS server. If mutual authentication is required the IPFIX
node acting as TLS server MUST request a certificate from the IPFIX
node acting as TLS client, and the IPFIX node acting as TLS client
MUST be prepared to supply a certificate on request.
15.3
Protection against DoS attacks
An attacker may directly mount a DoS attack by generating large
amounts of traffic. If TCP is used for transport, then the flow to
the collector would back off due to congestion and eventually stall,
blinding the IPFIX system. An attack could then proceed without
further observation. SCTP-PR will have a different pathology under
such an attack. Stale data at the head of the queue will get flushed
giving some visibility of the attack. In case of UDP, IPFIX would
reduce to some sort of sampling meaning that some forensics may be
left.
To avoid blinding of the IPFIX system some mechanism for service
differentiation can be used to prioritizes IPFIX traffic over user
traffic. An alternative is to use a dedicated network for the
transport of IPFIX messages. By sending the IPFIX messages over a
dedicated network, IPFIX message loss induced by user traffic
congestion is minimized. However an attacker may trigger the
generation of excessive IPFIX messages, and to avoid information
loss during such an attack the IPFIX network must be adequately
sized.
15.4
When IPsec or TLS is not an option
The use of IPsec or TLS might not be an option because of
performance issues.
Without IPsec or TLS an IPFIX entity has no means to authenticate an
IPFIX entity other than the Source IP address. Useful protection is
gained by allocating Exporter and Collector IP addresses from ranges
that are excluded from use by user traffic and preventing spoofing
attacks by proper ingress filtering. Where large numbers of
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exporters, proxies and collectors are used in a network, it may be
tempting for the administrator to not impose source IP address
restrictions but this leaves a proxy or collector open to the
reception of invalid information. Using an open proxy or collector
is therefore to be deprecated.
If IP address spoofing can not be prevented some level of protection
against an insertion attack is required. With a modern
implementation of TCP with good ISN randomization [XXX-REFERENCE] or
SCTP insertion such attacks are difficult without the ability to
snoop the packet flow [XXX-SCTP-BLIND-SPOOFING-REFERENCE]. UDP is
vulnerable to insertion attacks however, randomization of the IPFIX
sequence number might mitigate this problem. In all these cases, the
sequence number space is relatively small giving only limited
protection. Therefore a 64 bit cookie [L2TPv3] SHOULD be included as
an element within all messages.
The use of a dedicated network prevents IPFIX messages from being
inspected by an attacker.
15.5
Logging an IPFIX Attack
A Collector may detect problems by tracking the IPFIX sequence
number and therefore SHOULD provide a logging mechanism for tracking
out of sequence messages. [EDITORS NOTE: Double check whether this
is already specified in an earlier section.] Such out of sequence
messages may not only be caused by network congestion or
Exporter/Collector resource exhaustion but also by an attacker
injecting false messages.
Note that an attacker may be able to exploit the behavior of the
Collector when it receives an out of sequence message. For example
a Collector that simply reset the expected sequence number upon
receipt of a later message would easily be temporarily blinded by
deliberately injecting messages with a much larger sequence number.
[EDITORS NOTE: the security section may need be adapted to the
revised transport section]
16.
IANA Considerations
IANA will need to set up a registry of Flowset IDs, field types,
scope and option codepoints.
In compiling the registry of field types IANA must set asside a
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range value for vendor use. It is proposed that the range <0..32767>
be administered by IANA for IETF defined IEs, and that the range
<32768..65535> be allocated for private use by vendors.
Similarly the scope and option codepoints need to be split between
IANA administered and private ranges.
17.
Examples
Let's consider the example of an IPFIX Message composed of a
Template FlowSet, a Data FlowSet (which contains three Flow Data
Records), an Options Template FlowSet and a Data FlowSet (which
contains 2 Options Data Records).
IPFIX Message:
+--------+---------------------------------------------. . .
| | +--------------+ +-----------------------+
|Message | | Template | | Data |
| Header | | FlowSet | | FlowSet | . . .
| | | (1 Template) | | (3 Flow Data Records) |
| | +--------------+ +-----------------------+
+--------+---------------------------------------------. . .
. . .+-------------------------------------------------+
+------------------+ +--------------------------+ |
| Options | | Data | |
. . .| Template FlowSet | | FlowSet | |
| (1 Template) | | (2 Options Data Records) | |
+------------------+ +--------------------------+ |
. . .--------------------------------------------------+
17.1
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 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17.2
Template FlowSet Example
We want to report the following Field Types:
- The source IP address (IPv4), so the length is 4
- The destination IP address (IPv4), so the length is 4
- The next-hop IP address (IPv4), so the length is 4
- The number of bytes of the Flow
- The number of packets of the Flow
Therefore, the Template FlowSet 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 0 | Length = 28 bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 256 | Field Count = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP_SRC_ADDR = 0x0008 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP_DST_ADDR = 0x000C | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP_NEXT_HOP = 0x000F | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IN_PKTS = 0x0002 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IN_BYTES = 0x0001 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17.3
Data FlowSet Example
In this example, we report the following three Flow records:
Src IP addr. | Dst IP addr. | Next Hop addr. | Packet | Bytes
| | | Number | Number
---------------------------------------------------------------
198.168.1.12 | 10.5.12.254 | 192.168.1.1 | 5009 | 5344385
192.168.1.27 | 10.5.12.23 | 192.168.1.1 | 748 | 388934
192.168.1.56 | 10.5.12.65 | 192.168.1.1 | 5 | 6534
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 256 | Length = 64 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 198.168.1.12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 10.5.12.254 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.168.1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5009 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5344385 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.168.1.27 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 10.5.12.23 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.168.1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 748 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 388934 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.168.1.56 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 10.5.12.65 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 192.168.1.1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 6534 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note that padding was not necessary in this example.
17.4
Options Template FlowSet Example
Per line card (the router being composed of two line cards), we want
to report the following Field Types:
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- Total number of IPFIX Messages
- Total number of exported Flows
The format of the Options Template FlowSet 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 1 | Length = 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 257 | Option Scope Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Length = 8 | Scope 1 Field Type = 0x0003 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 2 | TOTAL_EXP_PKTS_SENT = 41 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 | TOTAL_FLOWS_EXP = 42 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
17.5
Data FlowSet with Options Data Records Example
In this example, we report the following two records:
Line Card ID | IPFIX Message| Export Flow
------------------------------------------
Line Card 1 | 345 | 10201
Line Card 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FlowSet ID = 257 | Length = 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 | 345 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 10201 | 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 2 | 690 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 20402 | Padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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18.
References
18.1
Normative References
[IPFIX-ARCH] Sadasivan, G, Brownlee, N. "Architecture Model for IP
Flow Information Export" draft-ietf-ipfix-arch-02.txt", October 2003
[IPFIX-INFO] Calato, P, Meyer, J, Quittek, J, "Information Model for
IP Flow Information Export" draft-ietf-ipfix-info-02, November 2003
[IPFIX-AS] Claise, B, Fullmer, M, Calato, P, Penno, R, "IPFIX
Protocol Specifications", draft-ietf-ipfix-protocol-00.txt, June
2003
[UDP] Postel, J., "User Datagram Protocol" RFC 768, August 1980
[TCP] "TRANSMISSION CONTROL PROTOCOL DARPA INTERNET PROGRAM
PROTOCOL SPECIFICATION" RFC 793, September 1981
[RFC2960] Stewart, R. (ed.) "Stream Control Transmission Protocol",
RFC 2960, October 2000
[PR-SCTP] Stewart, R, Ramalho, M, Xie, Q, Tuexen, M, Conrad, P.
"SCTP Partial Reliability Extension", draft-ietf-tsvwg-prsctp-
03.txt, January 2004
18.2
Informative References
[IPFIX-REQ] Quittek, J, Zseby, T, Claise, B, Zander, S,
"Requirements for IP Flow Information Export" draft-ietf-ipfix-reqs-
15.txt, June 2003
[IPFIX-AS] Zseby, T, Penno, R, Brownlee, N, Claise, B, "IPFIX
Applicability", draft-ietf-ipfix-as-01.txt, October 2003
[IPFIX-EVAL] Leinen, S, "Evaluation of Candidate Protocols for IP
Flow Information Export (IPFIX)", draft-leinen-ipfix-eval-contrib-
02.txt, January 2003
[NETFLOW9] Claise, B, et al "Cisco Systems NetFlow Services Export
Version 9", draft-claise-netflow-9-07.txt, December 2003
Claise, et. al Standard Track [Page 51]
IPFIX Protocol Specifications February 2004
[PEN] IANA Private Enterprise Numbers registry
http://www.iana.org/assignments/enterprise-numbers
[USEIPSEC] S. Bellovin, Guidelines for Mandating the Use of IPsec,
draft-bellovin-useipsec-02.txt, October 2003, work
in progress.
[IKE] Harkins, D. and D. Carrel, "The Internet Key Exchange
(IKE)", RFC 2409, November 1998.
[TLS] Dierks, T. and C. Allen, "The TLS Protocol Version
1.0", RFC 2246, January 1999.
[L2TPv3] J. Lau et al. Layer Two Tunneling Protocol (Version 3)
draft-ietf-l2tpext-l2tp-base-11.txt, October 2003, work
in progress.
[XXX-REFERENCE]
[XXX-SCTP-BLIND-SPOOFING-REFERENCE]
19.
Acknowledgments
We would like to thank the following persons for their valuable
technical feedback: Juergen Quittek, Sebastian Zander, Dave Plonka,
Jeff Meyer, Maurizio Molina, Carter Bullard, Randall Stewart, Peter
Lei, Tal Givoly and many more.
Authors Addresses
Benoit Claise
Cisco Systems
De Kleetlaan 6a b1
1831 Diegem
Belgium
Phone: +32 2 704 5622
E-mail: bclaise@cisco.com
Mark Fullmer
OARnet
2455 North Star Rd.
Claise, et. al Standard Track [Page 52]
IPFIX Protocol Specifications February 2004
Columbus, Ohio 43221
Phone: +1 (614) 728-8100
Email: maf@eng.oar.net
Reinaldo Penno
Nortel Networks
2305 Mission College Blvd
Santa Clara, CA 95054
Phone: +1 408.565.3023
Email: rpenno@nortelnetworks.com
Paul Calato
Riverstone Networks, Inc.
5200 Great America Parkway
Santa Clara, CA 95054 USA
Phone: +1 (603) 557-6913
Email: calato@riverstonenet.com
Ganesh Sadasivan
Cisco Systems, Inc.
170 W. Tasman Dr.
San Jose, CA 95134
USA
Phone: +1 (408) 527-0251
Email: gsadasiv@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
Claise, et. al Standard Track [Page 53]
