One document matched: draft-ietf-ipfix-reducing-redundancy-01.txt
Differences from draft-ietf-ipfix-reducing-redundancy-00.txt
Internet-Draft E. Boschi
draft-ietf-ipfix-reducing-redundancy-01.txt Hitachi Europe
Expires: April 26, 2007 L. Mark
Fraunhofer FOKUS
B. Claise
Cisco Systems
October 23, 2006
Reducing redundancy in IPFIX and PSAMP reports
draft-ietf-ipfix-reducing-redundancy-01
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Copyright Notice
Copyright (C) The Internet Society (2006).
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Abstract
This document describes a bandwidth saving method for exporting flow
or packet information using the IP Flow Information Export (IPFIX)
protocol. As the PSAMP protocol is based on IPFIX, these
considerations are valid for PSAMP exports as well.
This method works by separating information common to several flow
records from information specific to an individual flow record.
Common flow information is exported only once in a data record
defined by an option template, while the rest of the specific flow
information is associated with the common information via a unique
identifier.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Table of Contents
Copyright Notice...............................................1
Abstract.......................................................2
1. Introduction..............................................3
1.1 IPFIX Documents Overview...............................4
1.2 PSAMP Documents Overview...............................4
2. Terminology...............................................4
2.1 Terminology Summary Table.............................10
2.2 IPFIX Flows versus PSAMP Packets......................10
3. Problem Statement and High Level Solution................10
3.1 Per Flow Data Reduction...............................11
3.1.1 Unique Data Reduction..................................11
3.1.2 Multiple Data Reduction................................12
3.2 Per Packet Data Reduction.............................13
4. Specifications for bandwidth saving information export...15
4.1 Per Flow Data Reduction...............................15
4.1.1 Unique Data Reduction..................................15
4.1.2 Multiple Data Reduction................................17
4.2 Per-Packet Data Reduction.............................17
5. Transport Protocol Choice................................18
5.1 PR-SCTP...............................................18
5.2 UDP...................................................18
5.3 TCP...................................................18
6. commonPropertiesID Management............................18
7. The Collecting Process Side..............................19
7.1 UDP...................................................20
7.2 TCP...................................................21
8. Export and Evaluation Considerations.....................21
8.1 Transport Protocol Choice.............................22
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8.2 Reduced Size Encoding.................................22
8.3 commonPropertiesID vs. TemplateID scope...............22
8.4 Efficiency Gain.......................................22
9. IANA Considerations......................................22
10. Security Considerations..................................23
11. Appendix A: Examples.....................................23
11.1 Per Flow Data Reduction...............................23
11.1.1 Unique Data Reduction.................................23
11.1.2 Multiple Data Reduction...............................26
11.2 Per-Packet Information Export.........................30
11.3 commonPropertiesID Template Withdrawal Message........32
12. References...............................................33
12.1 Normative References..................................33
12.2 Informative References................................33
13. Acknowledgements.........................................34
14. Author's Addresses.......................................34
15. Intellectual Property Statement..........................35
16. Copyright Statement......................................35
17. Disclaimer...............................................35
1. Introduction
The IPFIX working group has specified a protocol to export IP Flow
information [IPFIX-PROTO]. This protocol is designed to export
information about IP traffic flows and related measurement data,
where a flow is defined by a set of key attributes (e.g. source and
destination IP address, source and destination port, etc.).
However, thanks to its template mechanism, the IPFIX protocol can
export any type of information, as long as the information element
is specified in [IPFIX-INFO] or registered with IANA.
Regardless of the fields content, flow records with common
properties export the same fields in every single flow record.
These common properties may represent values common to a collection
of flows or packets, or values that are invariant over time. The
reduction of redundant data from the export stream can result in a
significant reduction of the transferred data.
This draft specifies a way to export these invariant or common
properties only once, while the rest of the flow specific properties
are exported in regular data records. Unique common properties
identifiers are used to link data records and the common attributes.
The proposed method is applicable to IPFIX flow and to PSAMP per
packet information, without any changes to both the IPFIX and PSAMP
protocol specifications.
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1.1 IPFIX Documents Overview
The IPFIX protocol [IPFIX-PROTO] 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]. [IPFIX-ARCH] specifies how IPFIX
data record and templates are carried via a congestion-aware
transport protocol from IPFIX exporting processes to IPFIX
collecting process. IPFIX has a formal description of IPFIX
information elements, 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.
1.2 PSAMP Documents Overview
The document "A Framework for Packet Selection and Reporting" [PSAMP-
FMWK], describes the PSAMP framework for network elements to select
subsets of packets by statistical and other methods, and to export a
stream of reports on the selected packets to a collector. The set of
packet selection techniques (sampling, filtering, and hashing)
supported by PSAMP are described in "Sampling and Filtering
Techniques for IP Packet Selection" [PSAMP-TECH]. The PSAMP protocol
[PSAMP-PROTO] specifies the export of packet information from a PSAMP
exporting process to a PSAMP collecting process. Like IPFIX, PSAMP
has a formal description of its information elements, their name,
type and additional semantic information. The PSAMP information
model is defined in [PSAMP-INFO]. Finally [PSAMP-MIB] describes the
PSAMP Management Information Base.
2. Terminology
The terms in this section are in line with the IPFIX terminology
section [IPFIX-PROTO], and [PSAMP-PROTO]. Note that this document
selected the IPFIX definition of the term Exporting Process [IPFIX-
PROTO], as this definition is more generic than the PSAMP definition
[PSAMP-PROTO].
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.
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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 are also 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 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
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.
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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 which 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 Process.
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.
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Template
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.
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
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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
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 determines the valid encoding
mechanisms for use in IPFIX.
Observed Packet Stream
The Observed Packet Stream is the set of all packets observed
at the Observation Point.
Packet Content
The packet content denotes the union of the packet header
(which includes link layer, network layer and other
encapsulation headers) and the packet payload.
Selection Process
A Selection Process takes the Observed Packet Stream as its
input and selects a subset of that stream as its output.
Selector
A Selector defines the action of a Selection Process on a
single packet of its input. If selected, the packet becomes an
element of the output Packet Stream.
The Selector can make use of the following information in
determining whether a packet is selected:
(i) the Packet Content;
(ii) information derived from the packet's treatment at the
Observation Point;
(iii) any selection state that may be maintained by the
Selection Process.
PSAMP Device
A PSAMP Device is a device hosting at least an Observation
Point, a Selection Process and an Exporting Process.
Typically, corresponding Observation Point(s), Selection
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Process(es) and Exporting Process(es) are co-located at this
device, for example at a router.
Filtering
A filter is a Selector that selects a packet deterministically
based on the Packet Content, or its treatment, or functions of
these occurring in the Selection State. Examples include field
match Filtering, and Hash-based Selection.
commonPropertiesID
An identifier of a set of common properties that is locally
unique to an Exporting Process and to Observation Domain. This
ID can be used to link to information reported in separate
records. See [IPFIX-INFO] for the Information Element
definition.
Common Properties
Common Properties are a collection of one or more attributes
shared by a set of different Flow Records. Each set of Common
Properties is uniquely identifiable by means of a
commonPropertiesID.
Specific Properties
Specific Properties are a collection of one or more attributes
reported in a Flow Record that are not included in the Common
Properties defined for that Flow Record.
Transport Session
In SCTP, the transport session is known as the SCTP
association, which is uniquely identified by the SCTP endpoints
[RFC2960]; 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.
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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 1: 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).
2.2 IPFIX Flows versus PSAMP Packets
As described in [PSAMP-PROTO], the major difference between IPFIX and
PSAMP is that the IPFIX protocol exports Flow Records while the PSAMP
protocol exports Packet Records. From a pure export point of view,
IPFIX will not distinguish a Flow Record composed of several packets
aggregated together from a Flow Record composed of a single packet.
So the PSAMP export can be seen as special IPFIX Flow Record
containing information about a single packet.
For this document clarity, the term Flow Record represents a generic
term expressing an IPFIX Flow Record or a PSAMP packet record, as
foreseen by its definition. However, when appropriate, a clear
distinction between Flow Record or packet Record will be made.
3. Problem Statement and High Level Solution
Several Flow Records often share a set of common properties.
Repeating the information about these common properties for every
Flow Record introduces a huge amount of redundancy. This document
proposes a method to reduce this redundancy. The section 3.1.1
describes the generic concept. Section 3.1.2 identifies that the
proposed solution can be applied multiple times. Section 3.2
utilizes the concept to export per-packet information.
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3.1 Per Flow Data Reduction
3.1.1 Unique Data Reduction
Consider a set of properties "A", e.g. common sourceAddressA and
sourcePortA, equivalent for each Flow Records exported. Figure 2
shows how this information is repeated with classical IPFIX Flow
Records, expressing the waste of bandwidth to export redundant
information.
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <flow1 information> |
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <flow2 information> |
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <flow3 information> |
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <flow4 information> |
+----------------+-------------+---------------------------+
| ... | ... | ... |
+----------------+-------------+---------------------------+
Figure 2: Common and Specific Properties exported in the same record
Figure 3 shows how this information is exported when applying the
specifications of this document. The Common Properties are
separated from the Specific Properties for each Flow Record. The
Common Properties would be exported only once in a specific Data
Record (defined by an Option Template), while each Flow Record
contains a pointer to the Common Properties A, along with its Flow
specific information. In order to maintain the relationship between
these sets of properties, we introduce indices (in this case: index
for properties A) for the Common Properties that are unique for all
Common Properties entries within an Observation Domain. The purpose
of the indices is to serve as a "key" identifying "rows" of the
Common Properties table. The rows are then referenced by the
Specific Properties by using the appropriate value for the Common
Properties identifier.
+------------------------+-----------------+-------------+
| index for properties A | sourceAddressA | sourcePortA |
+------------------------+-----------------+-------------+
| ... | ... | ... |
+------------------------+-----------------+-------------+
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+------------------------+---------------------------+
| index for properties A | <flow1 information> |
+------------------------+---------------------------+
| index for properties A | <flow2 information> |
+------------------------+---------------------------+
| index for properties A | <flow3 information> |
+------------------------+---------------------------+
| index for properties A | <flow4 information> |
+------------------------+---------------------------+
Figure 3: Common and Specific Properties exported in different
records
This unique export of the Common Properties results in a decrease of
the bandwidth requirements for the path between the Exporter and the
Collector.
3.1.2 Multiple Data Reduction
A Flow Record can refer to one or more Common Properties sets; the
use of multiple Common Properties can lead to more efficient
exports. Note that in the case of multiple Common Properties, the
different sets of Common Properties MUST be disjoint (i.e. MUST not
have information elements in common), to avoid potential collisions.
Consider a set of properties "A", e.g. common sourceAddressA and
sourcePortA and another set of properties "B", e.g.
destinationAddressB and destinationPortB. Figure 4 shows how this
information is repeated with classical IPFIX export in several Flow
Records.
+--------+--------+---------+---------+---------------------+
|srcAddrA|srcPortA|destAddrB|destPortB| <flow1 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrA|srcPortA|destAddrC|destPortC| <flow2 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrD|srcPortD|destAddrB|destPortB| <flow3 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrE|srcPortE|destAddrF|destPortF| <flow4 information> |
+--------+--------+---------+---------+---------------------+
| ... | ... | ... | ... | ... |
+--------+--------+---------+---------+---------------------+
Figure 4: Common and Specific Properties exported in the same record
We can separate the Common Properties into the properties A composed
of sourceAddressA and sourcePortA, and into the properties B
composed of destinationAddressB and destinationPortB. The Flow
Record that only contain the property A will only contain the index
for property A, the Flow Record that only contain the property B
will contain the index for property B, while the Flow Record that
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contain both the properties A and B contains both indexes (see
Figure 5).
+-------------------+-----------------+-------------+
| index for prop. A | sourceAddressA | sourcePortA |
+-------------------+-----------------+-------------+
+-------------------+---------------------+------------------+
| index for prop. B | destinationAddressB | destinationPortB |
+-------------------+---------------------+------------------+
+-----------------+-----------------+-----------------------+
|index for prop. A|index for prop. B| <flow1 information> |
+-----------------+-----------------+-----------------------+
|index for prop. A| <flow2 information> |
+-----------------+-----------------+-----------------------+
|index for prop. B| <flow3 information> |
+-----------------+-----------------+-----------------------+
| <flow4 information> |
+-----------------+-----------------+-----------------------+
Figure 5: Multiple Common (above) and Specific Properties (below)
exported in different records
The advantage of the multiple Common Properties is that the
objective of reducing the bandwidth is met while the number of index
is kept to a minimum. Indeed, an alternative solution would have
been to have an extra index for the property C, composed of
sourceAddressA, sourcePortA, destinationAddressB, destinationPortB.
3.2 Per Packet Data Reduction
The PSAMP specifications are used for the export of per-packet
information, exporting the specific observed packet in an IPFIX Flow
Record. This can be considered as a special Flow Record case,
composed of a single packet.
If filtering is applied to select a series of packets, using the
PSAMP specifications to export per-packet information might be
relatively inefficient if the filtered fields (the common
attributes) are exported in every single record. For example, if
filtering restricts the observation of packets to the packets having
the source IP address A, exporting the common properties (the source
IP address A) in every record is not efficient.
Figure 6, which displays the high level solution for the per-packet
reduction, depicts three packets belonging to different flows, as
the destination IP address is different. Note that all packets
share the same source IP address A. The export of the source IP
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address A introduces a huge amount of redundancy, as they are
repeated for every packet in every Data Record.
+----------+-----------+--------------------------+
| srcAddrA | destAddrB | <packet1 information> |
+----------+-----------+--------------------------+
| srcAddrA | destAddrC | <packet2 information> |
+----------+-----------+--------------------------+
| srcAddrA | destAddrD | <packet3 information> |
+----------+-----------+--------------------------+
Figure 6: Common and Specific Properties represented in one record
In Figure 7 we separate Common Properties from Specific Properties,
i.e. Common Properties from specific packet information. In order
to maintain the relation between Specific (Packet) Properties and
Common Properties we introduce indices (index for properties A and
index B for properties B), as previously explained.
+----------+------------------------+
| srcAddrA | index for properties A |
+----------+------------------------+
+------------------------+-----------+-----------------------+
| index for properties A | destAddrB | <packet1 information> |
+------------------------+-----------+-----------------------+
| index for properties A | destAddrC | <packet2 information> |
+------------------------+-----------+-----------------------+
| index for properties A | destAddrD | <packet3 information> |
+------------------------+-----------+-----------------------+
Figure 7: Common and Specific (packet) Properties exported
separately
An example of the per packet data reduction is the measurement of
One-Way Delay (OWD), where the exact same specific packet must be
observed at the source and destination of the path to be measured.
By subtracting the time of observation of the same packet at the two
end points with synchronized clocks, the OWD is computed. As the
OWD is measured for a specific application on which a Service Level
Agreement (SLA) is bound, this translates into the observation of
multiple packets with specific properties, results of filtering. In
order to match the identical packet at both Observation Points, a
series of packets with a set of properties (For example, all the
packets of a specific source and destination IP addresses, of a
specific DSCP value, and of a specific destination transport port)
must be observed at both ends of the measurements. This implies
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that the source and destination must export of a series of Flow
Records composed of two types of information: some common
information for all packets, and some unique information about
packets in order to generate a unique identifier for each packet
passing this Observation Point (for example, a hash value on the
invariant fields of the packet). So, the source and destination
composing the measurements end points can individually and
independently apply the redundancy technique described in this draft
in order to save some bandwidth for their respective Flow Records
export.
4. Specifications for bandwidth saving information export
The IPFIX protocol [IPFIX-PROTO] is Template based. Templates
define how data should be exported, describing data fields together
with their type and meaning. IPFIX specifies two types of
Templates: the Template Record and the Options Template Record. The
difference between the two is that the Options Template Record
includes the notion of scope, defining how to scope the
applicability of the Data Record. The scope, which is only
available in the Options Template Record, gives the context of the
reported Information Elements in the Data Records. The Template
Records and Options Template Records are necessary to decode the
Data Records. Indeed, by only looking at the Data Records
themselves, this is impossible to distinguish a Data Record defined
by Template Record from a Data Record defined by an Option Template
Record. To export information more efficiently, this specification
proposes to group Flow Records by their common properties. We
define Common Properties as a collection of attributes shared by a
set of different Flow Records.
An implementation using the proposed specification MUST follow the
IPFIX transport protocol specifications defined in [IPFIX-PROTO].
4.1 Per Flow Data Reduction
4.1.1 Unique Data Reduction
As explained in Figure 8, the information is split into two parts,
using two different Data Records. Common Properties MUST be
exported via Data Records defined by an Option Template Record and
MUST be sent only once with the reliable stream of PR-SCTP
association or within the TCP connection. These properties
represent values common to several Flow Records (e.g. IP source and
destination address). The Common Properties Data Records MUST be
sent prior to the corresponding Specific Properties Data Records.
The Data Records reporting Specific Properties MUST be associated
with the Data Records reporting the Common Properties using a unique
identifier for the Common Properties, the commonPropertiesID
Information Element [IPFIX-INFO]. The commonPropertiesID MUST be
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exported as the scope in the Options Template Record, and also
exported in the associated Template Record.
+---------------------------+ +---------------------+
| Common Properties | | Specific Properties | Template
| Option Template Record | | Template Record | Definition
| | | |
| scope: commonPropertiesID | | commonPropertiesID |
| Common Properties | | Specific Properties |
+------------+--------------+ +---------+-----------+
.............|...............................|.......................
| |
+------------v-------------+ +----------v----------+
| Common Properties | | Specific Properties |+ Exported
| Data Record |------> Data Records || Data
+--------------------------+ +---------------------+| Records
+---------------------+
Figure 8: Template Record and Data Record dependencies
The assignment of Flow Records to common attributes could be
alternatively provided by the templateID Information Element
(instead of the commonPropertiesID Information Element). In this
case, the scope in the Common Properties Option Template Record must
contain the Template ID used in the Specific Properties Template
Record, as displayed in Figure 9. The Common Properties are valid
for all data records of the specified Template. In this case the
use of commonPropertiesID is not required.
+---------------------------+ +---------------------+
| Common Properties | | Specific Properties | Template
| Option Template Record | | Template Record | Definition
| | | |
| scope: Template ID | | Specific Properties |
| Common Sroperties | | |
+------------+--------------+ +---------+-----------+
.............|...............................|.......................
| |
+------------v-------------+ +----------v----------+
| Common Properties | | Specific Properties |+ Exported
| Data Record |------> Data Records || Data
+--------------------------+ +---------------------+| Records
+---------------------+
Figure 9: Template Records and Data Records linked with TemplateID
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4.1.2 Multiple Data Reduction
If a set of Flow Records share multiple sets of Common Properties,
multiple commonPropertiesID instances MAY be used to increase export
efficiency even further, as displayed in the Figure 10.
+----------------------------+ +---------------------+
| Common Properties | | Specific Properties | Template
| Option Template Record | | Template Record | Definition
| | | |
| Scope: commonPropertiesID1 | | commonPropertiesID1 |
| Scope: commonPropertiesID2 | | commonPropertiesID2 |
| Common Properties | | Specific Properties |
+------------+---------------+ +---------+-----------+
.............|...............................|.......................
| |
+------------v-------------+ +----------v----------+
| Common Properties | | Specific Properties |+ Exported
| Data Record |------> Data Records || Data
+--------------------------+ +---------------------+| Records
+---------------------+
Figure 10: Multiple data reduction
4.2 Per-Packet Data Reduction
From the IPFIX protocol, there are no differences between the Flow
Record or per packet record data reduction, except maybe the
terminology where the Specific Properties could be called packet
specific properties in the following Figure 11.
+---------------------------+ +---------------------+
| Common Properties | | Specific Properties | Template
| Option Template Record | | Template Record | Definition
| | | |
| scope: commonPropertiesID | | commonPropertiesID |
| Common Properties | | Specific Properties |
+------------+--------------+ +---------+-----------+
.............|...............................|.......................
| |
+------------v-------------+ +----------v----------+
| Common Properties | | Specific Properties |+ Exported
| Data Record |------> Data Records || Data
+--------------------------+ +---------------------+| Records
+---------------------+
Figure 11: Per-packet data reduction
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5. Transport Protocol Choice
This document follows the IPFIX transport protocol specifications
defined in [IPFIX-PROTO]. However, depending on the transport
protocol choice, this document imposes some more constraints. If
PR-SCTP is selected as the IPFIX protocol, the SCTP sub-section
specifications MUST be respected. If UDP is selected as the IPFIX
protocol, the UDP sub-section specifications MUST be respected. If
TCP is selected as the IPFIX protocol, the TCP sub-section
specifications MUST be respected.
5.1 PR-SCTP
The active Common Properties MUST be sent after the SCTP association
establishment before the corresponding Specific Properties Data
Records. In case of SCTP association re-establishment, all active
Common Properties MUST be re-sent before the corresponding Specific
Properties Data Records.
The Common Properties Flow Records MUST be sent on a reliable SCTP
stream.
5.2 UDP
Common Properties Data Records MUST be re-sent at regular intervals,
whose frequency MUST be configurable. The default value for the
frequency of Common Properties transmission is 10 minutes.
If a commonPropertiesID is not used anymore the Exporting Process
stops re-sending the related Common Properties Data Record. The old
commonPropertiesID MUST NOT be used until its lifetime (see 7.1) has
expired.
5.3 TCP
Common Properties MUST be sent after the TCP connection
establishment before the corresponding Specific Properties Data
Records. In case of TCP connection re-establishment, all active
Common Properties MUST be re-sent before the corresponding Specific
Properties Data Records.
6. commonPropertiesID Management
The commonPropertiesId is an identifier of a set of common
properties that is locally unique per Observation Domain and
Transport Session. The Exporting Process MUST manage the
commonPropertiesIDs allocations for its Observation Domains and
Transport Session. Different Observation Domains from the same
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Exporter MAY use the same commonPropertiesID value to refer to
different sets of Common Properties.
The commonPropertiesID values MAY be assigned sequentially, but it’s
NOT REQUIRED. Particular commonPropertiesID ranges or values MAY
have explicit meanings for the IPFIX Device. For example,
commonPropertiesID values may be assigned based on the result of a
hash function, etc...
Using a 64-bit commonPropertiesID Information Element allows the
export of 2**64 -1 active sets of Common Properties, per Observation
Domain and per Transport Session: as consequence, per Exporting
Process.
commonPropertiesIDs that are not used anymore SHOULD be withdrawn.
The Common Properties ID withdrawal message is an Option Data Record
consisting of only one scope field namely the commonPropertiesID
(with a type of 137 [IPFIX-INFO]) and no non-scope fields.
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 = 14 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID N | Field Count = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field count = 1 |0| commonPropertiesID = 137 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: commonPropertiesID Withdrawal Message
If UDP is selected as the transport protocol, the commonPropertiesID
Template Withdraw Messages MUST not be used, as this method is
inefficient due to the unreliable nature of UDP.
7. The Collecting Process 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 the subsections.
The Collecting Process MUST store the commonPropertiesId information
for the duration of the association so that it can interpret the
corresponding Data Records that are received in subsequent Data Sets.
The Collecting Process can either store the Flow Records as they
arrive, without reconstructing the initial Flow Record, or
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reconstruct the initial Flow Record. In the former case, there
might be less storage capacity required at the Collector side. In
the latter case, the collector job is more complex and time-
consuming due to the higher resource demand for record processing in
real time.
If the Collecting Process has received the Specific Properties Data
Record before the associated Common Properties Data Record, the
Collecting Process MAY store the Specific Properties Data Record and
await the retransmission or out-of-order arrival of the Common
Properties Data Record.
Like TemplateIDs the commonPropertiesIDs are generated dynamically
by the Exporting Process. Hence a restart of the Exporting Process
may imply a renumbering of commonProperiesIDs.
Common Properties IDs are unique per SCTP association and per
Observation Domain. If the Collecting Process receives a common
Properties ID which has already been received but which has not
previously been withdrawn (i.e. a commonPropertiesID from the same
Exporter Observation Domain with the same Template ID received on the
SCTP association), then the Collecting Process MUST shutdown the
association.
When an SCTP association is closed, the Collecting Process MUST
discard all Common Properties IDs received over that association and
stop decoding IPFIX Messages that use those Common Properties IDs.
If a Collecting Process receives a Common Properties Withdrawal
message, the Collecting Process MUST delete the corresponding Common
Properties 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 Common Properties Withdrawal
message for a Common Properties that it has not received before on
this SCTP assocation, it MUST reset the SCTP association, discard the
IPFIX Message, and SHOULD log the error as it does for malformed
IPFIX Messages.
7.1 UDP
The Collecting Process MUST associate a lifetime with each Common
Property received via UDP. Common Properties not refreshed by the
Exporting Process within the lifetime are expired at the Collecting
Process.
If the Common Properties are not refreshed before that lifetime has
expired, the Collecting Process MUST discard the corresponding
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definition of the commonPropertiesID 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 which
are associated with the expired Common Properties. If a Common
Property is refreshed with a Template Record that differs from the
previous received Template Record, the Collecting Process SHOULD log
a warning and replace the previous received Common Property 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.
The Collecting Process SHOULD accept Data Records without the
associated Common Property(ies) required to decode the Data Record.
If the Common Property(ies) 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.
7.2 TCP
When the TCP connection is reset, either gracefully or abnormally,
the Collecting Processes MUST delete all commonPropertiesID values
corresponding to that connection.
If a Collection Process receives a commonPropertiesID Withdraw
message, the Collection Process MUST expire the related Common
Properties data.
8. Export and Evaluation Considerations
The main advantage of the method specified in this document is the
reduction in the amount of measurement data that has to be
transferred from the Exporter to the Collector. In addition there
might be less storage capacity required at the Collector side if the
Collector decides to store the Flow Records as they arrive, without
reconstructing the initial Flow Record.
On the other hand, these methods require additional resources on
both the Exporter and the Collector. The Exporter has to manage
Common Properties information and to assign commonPropertiesId
values to Flow Records. The Collector has to process records
described by two templates instead of just one. Additional effort
is also required when post processing the measurement data, in order
to correlate Flow Records with Common Properties information.
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8.1 Transport Protocol Choice
The proposed method is most effective using a reliable transport
protocol for the transfer of the Common Properties. Therefore the
use of SCTP or TCP is recommended. However, if the path from the
Exporting Process to the Collecting Process is not fully reliable,
the SCTP or TCP retransmission might reduce the benefits of this
specification. If the path from the Exporting Process to the
Collecting Process is full reliable, the use of UDP is less
effective because the common properties have to be re-sent
regularly.
8.2 Reduced Size Encoding
The transfer of the commonPropertiesIDs originates some overhead.
Note that IPFIX allows reduced-size encoding of Information
Elements. In cases where the range of the commonPropertiesID can be
restricted, reduced-size encoding can be applied also to the
commonPropertiesID, and would result in a further bandwidth
efficiency gain.
8.3 commonPropertiesID vs. TemplateID scope
The assignment of Flow Records to common attributes could be done
via the commonPropertiesID and alternatively via the templateID
Information Element. In the second case the commonPropertiesID is
not required: this reduces the overhead but the Exporting Process
must use one templateID per set of Common Properties. In the
general case, this method is not scalable, but it can be suitable
for certain applications.
8.4 Efficiency Gain
The example in section 11.2 below uses IPFIX to export measurement
data for each received packet. In that case, for a flow of 1000
packets the amount of data can be decreased more than 33 percent.
While the goal of this specification is to reduce the bandwidth, the
efficiency might be limited. Indeed, the efficiency gain is based
on the numerous redundant information in flows. While the Exporting
Process can evaluate the direct gain for the Flow Records to be
exported, it can’t predict whether future Flow Records would contain
the information specified by active commonPropertiesID values. This
implies that the efficiency factor of this specification is higher
for specific applications where filtering is involved, such as one-
way delay or trajectory sampling.
9. IANA Considerations
This document has no actions for IANA.
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10. Security Considerations
For the proposed use of the IPFIX protocol for bandwidth-saving
export the security considerations as for the IPFIX protocol apply.
11. Appendix A: Examples
11.1 Per Flow Data Reduction
11.1.1 Unique Data Reduction
In this section we show how flow information can be exported
efficiently using the method described in this draft. Let's suppose
we have to periodically export data about two IPv6 Flows.
In this example we report the following information:
Flow| dstIPv6Address | dst- |nPkts|nBytes
| | Port | |
----------------------------------------------------------------
A |5F05:2000:80AD:5800:0058:0800:2023:1D71| 80 | 30 | 6000
| | | |
A |5F05:2000:80AD:5800:0058:0800:2023:1D71| 80 | 50 | 9500
| | | |
B |5F05:2000:80AD:5800:0058:00AA:00B7:AF2B| 1932 | 60 | 8000
| | | |
A |5F05:2000:80AD:5800:0058:0800:2023:1D71| 80 | 40 | 6500
| | | |
A |5F05:2000:80AD:5800:0058:0800:2023:1D71| 80 | 60 | 9500
| | | |
B |5F05:2000:80AD:5800:0058:00AA:00B7:AF2B| 1932 | 54 | 7600
The Common Properties in this case are the destination IPv6 address
and the destination port. We first define an Option Template that
contains the following Information Elements:
- Scope: the commonPropertiesID, with a type of 137 [IPFIX-INFO]
and a length of 8 octets.
- The destination IPv6 address, destinationIPv6Address [IPFIX-
INFO], with a type of 28 and a length of 16 octets
- The destination port, destinationTransportPort [IPFIX-INFO]
with a type of 11, and a length of 2 octets
Figure 13 shows the Option template defining the Common Properties
with commonPropertiesID as scope:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length = 24 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 257 | Field Count = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field count = 1 |0| commonPropertiesID = 137 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 8 |0| destinationIPv6Address = 28|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 16 |0|destinationTransportPort = 11|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 | (Padding) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Common Properties Option Template
The Specific Properties Template consists of the information not
contained in the Option Templates, i.e. flow specific information,
in this case the number of packets and the number of bytes to be
reported. Additionally, this Template contains the
commonPropertiesID. In Data Records, the value of this field will
contain one of the unique indices of the Option Records exported
before. It contains the following Information Elements (see also
Figure 14):
- commonPropertiesID with a length of 8 octets
- The number of packets of the Flow: inPacketDeltaCount in
[IPFIX-INFO], with a length of 4 octets
- The number of octets of the Flow: inOctetDeltaCount in [IPFIX-
INFO], with a length of 4 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 2 | Length = 20 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 258 | Field Count = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| commonPropertiesID = 137 | Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inPacketDeltaCount = 2 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inOctetDeltaCount = 1 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: Specific Properties Template
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Considering the data shown at the beginning of this example, the
following two Data Records will be exported:
Common- | dstAddress | dst-
PropertiesID | | Port
-------------+-----------------------------------------+-------
101 | 5F05:2000:80AD:5800:0058:0800:2023:1D71 | 80
| |
102 | 5F05:2000:80AD:5800:0058:00AA:00B7:AF2B | 1932
The Data Records reporting the Common Properties will look like:
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 = 257 | Length = 60 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 101 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5F05:2000: ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... 80AD:5800: ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... 0058:0800: ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... 2023:1D71 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 80 | (Padding) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 102 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5F05:2000: ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... 80AD:5800: ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... 0058:00AA: ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... 00B7:AF2B |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1932 | (Padding) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: Data Records reporting Common Properties
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The Data Records will in turn be:
commonPropertiesID | inPacketDeltaCount | inOctetDeltaCount
---------------------------------------------------------------
101 | 30 | 6000
101 | 50 | 9500
102 | 60 | 8000
101 | 40 | 6500
101 | 60 | 9500
102 | 54 | 7600
Figure 16 shows the first Data Record listed in the table:
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 = 258 | Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 101 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 30 | 6000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: Data Record reporting Specific Properties
11.1.2 Multiple Data Reduction
In this example we export the following flow information:
Flow | srcAddr | srcPort | dstAddr | dstPort | nPackets | nBytes
----------------------------------------------------------------
A |10.0.0.1 | 1932 |10.0.1.2 | 80 | 30 | 6000
B |10.0.0.3 | 2032 |10.0.1.2 | 80 | 50 | 9500
Figure 17 shows the Option Templates, containing the Common
Properties together with the commonPropertiesID as Scope.
In the first Common Properties Option Template we export the
following Information Elements:
- Scope 1: the Common Properties ID, commonPropertiesId with a
type of 137 [IPFIX-INFO]. Note that the commonProperties IE
has a length of 8 octets, but if smaller size is sufficient to
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carry any value the Exporter may need to deliver, reduced size
encoding can be used. In this example we use reduced sizing,
of 4 octets.
- the source IPv4 Address, sourceIPv4Address [IPFIX-INFO], with a
type of 8 and a length of 4 octets
- the source Port, sourceTransportPort [IPFIX-INFO], with a type
of 7 and a length of 2 octets
The second Option Template contains the following Information
Elements:
- Scope 2: the commonPropertiesID, with a type of 137 [IPFIX-
INFO] and a length of 4 octets (reduced sizing).
- the destination IPv4 Address, destinationIPv4Address [IPFIX-
INFO], with a type of 12 and a length of 4 octets
- the destination port, destinationTransportPort [IPFIX-INFO]
with a type of 11, and a length of 2 octets
The commonPropertiesId Information Element is used in both cases as
the Scope Field.
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 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 256 | Field Count = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field count = 1 |0| commonPropertiesID = 137 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 |0| sourceIPv4Address = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 |0| transportSourcePort = 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 | (Padding) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 3 | Length = 24 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 257 | Field Count = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field count = 1 |0| commonPropertiesID = 137 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 |0| destinationIPv4Address = 12|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 |0|transportDestinationPort = 11|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 | (Padding) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: Example Common Properties Template
Considering the values given at the beginning of this section we
will export the Common Properties using the following Data Records:
commonPropertiesID | sourceAddress | sourcePort
--------------------+-----------------+-------------
101 | 10.0.0.1 | 1932
102 | 10.0.0.3 | 2032
and
commonPropertiesID | dstAddress | dstPort
--------------------+---------------+-----------
103 | 10.0.1.2 | 80
The Specific Properties Template consists of the information not
contained in the Option Templates, i.e. flow specific information.
Additionally, this Template contains the two commonPropertiesID. In
Data Records, the values of each of these fields will contain one of
the unique indices specified in the Option Records exported
previously.
Figure 18 displays the Template including the commonPropertiesID
plus the Specific Properties. In this example we export the
following Information Elements:
- commonPropertiesID for the source fields with a length of 4
octets (reduced size encoding)
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- commonPropertiesID for the destination fields with a length of
4 octets (reduced size encoding)
- the number of packets of the Flow: inPacketDeltaCount in
[IPFIX-INFO], with a length of 4 octets
- the number of octets of the Flow: inOctetDeltaCount in [IPFIX-
INFO], with a length of 4 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 2 | Length = 24 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 259 | Field Count = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| commonPropertiesID = 137 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| commonPropertiesID = 137 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inPacketDeltaCount = 2 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inOctetDeltaCount = 1 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 18: Example Specific Properties Template
Considering the values given at the beginning of this section, the
Data Records of the two flows will look like:
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 = 28 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 101 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 103 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 30 | 6000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 102 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 103 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 50 | 9500 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 19: Specific Properties
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11.2 Per-Packet Information Export
This section demonstrates per-packet information export to support
passive One-Way Delay (OWD) measurement. The Templates required for
exporting measurement data of this kind are illustrated in the
figures below.
Figure 20 shows the Option Template containing the information
concerning Flows using the commonPropertiesID as scope. In the
Common Properties Template we export the following Information
Elements:
- the source IPv4 Address, sourceIPv4Address [IPFIX-INFO], with a
type of 8 and a length of 4 octets
- the destination IPv4 Address, destinationIPv4Address [IPFIX-
INFO], with a type of 12 and a length of 4 octets
- the Class of Service field, ClassOfServiceIPv4 [IPFIX-INFO],
with a type of 5 and a length of 1 octet
- the Protocol Identifier, protocolIdentifier [IPFIX-INFO], with
a type of 4 and a length of 1 octet
- source port, sourceTransportPort [IPFIX-INFO], with a type of 7
and and a length of 2 octets
- destination port, destinationTransportPort [IPFIX-INFO], with a
type of 11 and a length of 2 octets
The commonPropertiesID Information Element, is used as the Scope
Field.
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 = 40 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 256 | Field Count = 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field count = 1 |0| commonPropertiesID = XX |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 4 |0| sourceIPv4Address = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 |0| destinationIPv4Address = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 4 |0| classOfServiceIPv4 = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 1 |0| protocolIdentifier = 4 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 1 |0| transportSourcePort = 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |0|transportDestinationPort = 11|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 | (Padding) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 20: Example Flow Properties Template
For passive One-Way-Delay measurement, the Packet Properties
Template, or Specific Properties Template, consists of at least
Timestamp and Packet ID. Additionally, this template contains a
commonPropertiesId field to associate the packet with a Flow.
Figure 21 displays the template with the packet properties. In this
example we export the following Information Elements:
- commonPropertiesID. In this case reduced size encoding is used,
and the Information Element is declared with a length of 4
octets instead of 8.
- packetTimestamp, packetID, and packetLength. Since
packetTimestamp, packetID, and packetLength are not (yet) IETF-
defined information elements, we export them as enterprise-
specific IEs. The three IEs have respectively a type of 220,
221, and 222 and a length of 8, 4, and 4 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Set ID = 2 | Length = 36 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID = 257 | Field Count = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| commonPropertiesID = 137 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| packetTimestamp = 220 | Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| packetID = 221 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| packetLength = 222 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Enterprise number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: Example Packet Properties Template
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Reducing redundancy in IPFIX and PSAMP reports
At the collection point, packet records from the two measurement
points are gathered and correlated by means of the packet ID. The
resulting delay data records are exported in a similar manner as the
packet data. One-way delay data is associated with flow information
by the commonPropertiesId field. The OWD properties contain the
Packet Pair ID (which is the packet ID of the two contributing
packet records), the timestamp of the packet passing the reference
monitor point in order to reconstruct a time series, the calculated
delay value, and the commonPropertiesID.
In this example using IPFIX to export the measurement data for each
received packet 30 bytes have to be transferred (sourceAddressV4=4,
destinationAddressV4=4, classOfServiceV4=1, protocolIdentifier=1,
sourceTransportPort=2, destionationTransportPort=2,
packetTimestamp=8, packetID=4, packetLength=4). Without considering
the IPFIX protocol overhead a flow of 1000 packets produces 30000
bytes of measurement data. Using the proposed optimization each
packet produces an export of only 20 bytes (packetTimestamp=8,
packetID=4, packetLength=4, commonPropertiesID=4). The export of
the flow information produces 18 bytes (sourceAddressV4=4,
destinationAddressV4=4, classOfServiceV4=1, protocolIdentifier=1,
sourceTransportPort=2, destionationTransportPort=2,
commonPropertiesID =4). For a flow of 1000 packets this sums up to
20018 bytes. This is a decrease of more than 33 percent.
11.3 commonPropertiesID Template Withdrawal Message
This section shows an example commonPropertiesIDs Withdrawal
message. Figure 22 depicts the Option Template Record with the
commonPropertiesID as unique scope field, and no non-scope fields.
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 = 14 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Template ID 259 | Field Count = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope Field count = 1 |0| commonPropertiesID 137 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 22: example commonPropertiesID withdrawal template
Figure 23 shows the Option Data Record withdrawing
commonPropertiesID N:
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Reducing redundancy in IPFIX and PSAMP reports
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 = 259 | Length = 12 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 23: commonPropertiesID withdrawal record, withdrawing
commonPropertiesID N
12. References
12.1 Normative References
[RFC2119] S. Bradner, Key words for use in RFCs to Indicate
Requirement Levels, BCP 14, RFC 2119, March 1997
[IPFIX-PROTO] B. Claise et Al, IPFIX Protocol Specification,
<draft-ietf-ipfix-protocol-23.txt>, Internet-Draft
work in progress, October 2006
[IPFIX-INFO] J. Quittek, S.Bryant, B.Claise, J. Meyer,
Information Model for IP Flow Information Export,
<draft-ietf-ipfix-info-13.txt>, Internet-draft work in
progress, September 2006
[PSAMP-PROTO] B. Claise, J. Quittek, A. Johnson, PSAMP Protocol
Specification, <draft-ietf-psamp-protocol-06.txt>,
Internet-Draft work in progress, June 2006
12.2 Informative References
[IPFIX-ARCH] G. Sadasivan, N. Brownlee, B. Claise, J. Quittek,
Architecture Model for IP Flow Information Export,
<draft-ietf-ipfix-arch-12.txt>, Internet-Draft work in
progress, September 2006
[IPFIX-AS] T. Zseby, E. Boschi, N. Brownlee, B. Claise, IPFIX
Applicability, <draft-ietf-ipfix-as-10.txt>, Internet-
Draft work in progress, August 2006
[PSAMP-TECH] T. Zseby, M. Molina, N. Duffield, S. Niccolini, F.
Raspall, Sampling and Filtering Techniques for IP
Packet Selection, <draft-ietf-psamp-sample-tech-
07.txt>, Internet-Draft work in progress, January 2006
Boschi, Mark, Claise Expires April 2007 [Page 33]
Reducing redundancy in IPFIX and PSAMP reports
[PSAMP-INFO] T. Dietz, F. Dressler, G. Carle, B. Claise, P. Aitken,
Information Model for Packet Sampling Exports, <draft-
ietf-psamp-info-04.txt>, Internet-Draft work in
progress, March 2006
[PSAMP-MIB] T. Dietz, B. Claise, Definitions of Managed Objects for
Packet Sampling, <draft-ietf-psamp-mib-06.txt>,
Internet-Draft work in progress, June 2006
[PSAMP-FMWK] N. Duffield, D. Chiou, B. Claise, A. Greenberg, M.
Grossglauser, P. Marimuthu, J. Rexford, G. Sadasivan, A
Framework for Passive Packet Measurement, <draft-ietf-
psamp-framework-10.txt>, Internet-Draft work in
progress, January 2005
[RFC3917] J. Quittek, T. Zseby, B. Claise, S. Zander,
Requirements for IP Flow Information Export, RFC 3917,
October 2004
13. Acknowledgements
The authors would like to thank Guido Pohl for initiating this work
and for his contribution to early versions of this document.
14. Author's Addresses
Elisa Boschi
Hitachi Europe SAS
Immeuble Le Theleme
1503 Route des Dolines
06560 Valbonne, France
Phone: +33 4 89874180
Email: elisa.boschi@hitachi-eu.com
Lutz Mark
Fraunhofer Institute for Open Communication Systems
Kaiserin-Augusta-Allee 31
10589 Berlin
Germany
Phone: +49-30-34 63 7306
Fax: +49-30-34 53 8306
Email: mark@fokus.fraunhofer.de
Benoit Claise
Cisco Systems
De Kleetlaan 6a b1
Diegem 1813
Belgium
Boschi, Mark, Claise Expires April 2007 [Page 34]
Reducing redundancy in IPFIX and PSAMP reports
Phone: +32 2 704 5622
Email: bclaise@cisco.com
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Boschi, Mark, Claise Expires April 2007 [Page 35]
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