Internet-Draft E. Boschi
draft-boschi-ipfix-reducing-redundancy-02.txt Hitachi Europe
Expires: December 27, 2006 L. Mark
Fraunhofer FOKUS
B. Claise
Cisco Systems
June 25, 2006
Reducing redundancy in IPFIX and PSAMP reports
draft-boschi-ipfix-reducing-redundancy-02.txt
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Copyright (C) The Internet Society (2006).
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Reducing redundancy in IPFIX and PSAMP reports
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······························3
1.2 PSAMP Documents Overview······························3
2. Terminology·············································4
2.1 Terminology Summary Table.····························8
2.2 IPFIX Flows versus PSAMP Packets······················8
3. Problem Statement and High Level Solution···············8
3.1 Per Flow Data Reduction·······························8
3.1.1 Unique Data Reduction..................................8
3.1.2 Multiple Data Reduction................................9
3.2 Per Packet Data Reduction····························11
4. Specifications for bandwidth saving information export·12
4.1 Per Flow Data Reduction······························13
4.1.1 Unique Data Reduction.................................13
4.1.2 Multiple Data Reduction...............................14
4.2 Per-Packet Data Reduction····························14
5. Transport Protocol Choice······························15
5.1 SCTP·················································15
5.2 UDP··················································15
5.3 TCP··················································15
6. commonPropertiesID Management··························16
7. The Collecting Process Side····························16
7.1 SCTP·················································17
7.2 UDP··················································17
7.3 TCP··················································17
8. Export and Evaluation Considerations···················17
8.1 Transport Protocol Choice····························18
8.2 Reduced Size Encoding································18
8.3 CommonPropertiesID vs. TemplateID scope··············18
8.4 Efficiency Gain······································18
9. IANA Considerations····································18
10. Security Considerations································18
11. Appendix A: Examples···································19
11.1 Per Flow Data Reduction······························19
11.1.1 Unique Data Reduction................................19
11.1.2 Multiple Data Reduction..............................22
11.2 Per-Packet Information Export························24
12. References·············································26
12.1 Normative References·································26
12.2 Informative References·······························27
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13. Author's Addresses·····································27
14. Intellectual Property Statement························28
15. Copyright Statement····································28
16. Disclaimer·············································28
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 flow attributes content, flow records with
common attributes export the same values in every single flow
record. These common attributes 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
attributes only once, while the rest of the flow specific
attributes 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.
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]. This document 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
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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.
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...)
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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.
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.
Template
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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 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.
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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
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.
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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
draft proposes a method to reduce this redundancy. The next
section 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.
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
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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 (index 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 |
+------------------------+-----------------+-------------+
| ... | ... | ... |
+------------------------+-----------------+-------------+
+------------------------+---------------------------+
| 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 from the Exporter to 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.
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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|destAddrB|destPortB| <flow2 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrA|srcPortA|destAddrB|destPortB| <flow3 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrA|srcPortA|destAddrB|destPortB| <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 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|index for prop. B| <flow2 information> |
+-----------------+-----------------+-----------------------+
|index for prop. A|index for prop. B| <flow3 information> |
+-----------------+-----------------+-----------------------+
|index for prop. A|index for prop. B| <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.
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3.2 Per Packet Data Reduction
The PSAMP protocol can be used for the export of per-packet
information. In this case the specific packet of observation
could be considered a special case of a Flow (a Flow Record
composed of a single packet) and consequently per-packet
information could be exported using Flow Records. However, if
filtering is applied to select a subset of all packets, using
IPFIX to export per-packet information is relatively inefficient
since all packets belonging to the same series share common
attributes (e.g. source address, destination address, etc).
A first 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 packets
with specific properties, results of filtering. 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. In order to match the identical
packet at both Observation Points, a series of packets with
those properties must be observed on both ends of the
measurements. This implies the 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 two IPFIX Devices
composing the measurements end points can individually apply the
redundancy technique described in this draft in order to save
some bandwidth for the Flow Records export.
A second example of per packet data reduction is trajectory
sampling.
[*** TODO: make the distinction between 1. temporal export of
same information from one PSAMP device 2. export of similar
information from different devices. The method in this document
only applies to 1.]
A third example of per packet data reduction is One-packet flows
exported from a single router with a zero second export.
[*** TODO: This would be an example of the I.E. 313
ipHeaderPacketSection and I.E 314 ipPayloadPacketSection in
PSAMP]
Figure 6, which displays the high level solution for the per
packet reduction, depicts three packets belonging to Flow A (and
therefore sharing the set of Common Properties A) and one packet
belonging to Flow B, respectively. It shows export records
containing packet specific information and the Common Properties
(source and destination address). The Common Properties
introduce a huge amount of redundancy, as they are repeated for
every packet in every Data Record.
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+----------+-----------+--------------------------+
| srcAddrA | destAddrA | <packet1 information> |
+----------+-----------+--------------------------+
| srcAddrA | destAddrA | <packet2 information> |
+----------+-----------+--------------------------+
| srcAddrB | destAddrB | <packet3 information> |
+----------+-----------+--------------------------+
| srcAddrA | destAddrA | <packet4 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 A and index B), as previously explained.
+----------+-----------+------------------------+
| srcAddrA | destAddrA | index for properties A |
+----------+-----------+------------------------+
| srcAddrB | destAddrB | index for properties B |
+----------+-----------+------------------------+
+------------------------+------------------+
| index for properties A | <packet1 info> |
+------------------------+------------------+
| index for properties A | <packet2 info> |
+------------------------+------------------+
| index for properties B | <packet3 info> |
+------------------------+------------------+
| index for properties A | <packet4 info> |
+------------------------+------------------+
Figure 7: Common and Specific (packet) Properties exported
separately
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.
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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 SCTP and TCP. 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. The
commonPropertiesID MUST be 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 Common Properties are valid for all Flow Records containing
the associated commonPropertiesID. Since the commonPropertiesID
is a 64-bit data type, this method limits the number of active
data reduction to 2**64 per Exporting Process and Observation
Domain.
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.
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+---------------------------+ +---------------------+
| 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
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.
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+---------------------------+ +---------------------+
| 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
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 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 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.
CommonPropertiesIDs have a specified lifetime during which they
cannot be reused. After that time a commonPropertiesID can be
assigned to another set of Common Properties. CommonPropertiesID
whose lifetime has longer expired SHOULD be preferred. The
lifetime MUST be configurable.
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.
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6. commonPropertiesID Management
The commonPropertiesID is an identifier of a set of common
properties that is locally unique to an Exporting Process and to
Observation Domain. The Exporting Process MUST manage the
commonPropertiesIDs allocations for its Observation Domains.
Different Observation Domains from the same Exporter MAY use the
same commonPropertiesID value to refer to different sets of
Common Properties.
The commonPropertiesID values MAY be assigned sequentially, but
its 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, 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 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 = XX |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Scope 1 Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: CommonPropertiesID withdrawal template
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 13: CommonPropertiesID withdrawal record, withdrawing
CommonPropertiesID N
7. The Collecting Process Side
The Collecting Process can either store the Flow Records as they
arrive, without reconstructing the initial Flow Record, or
reconstruct the initial Flow Record. In the former case there
might be less storage capacity required at the Collector side.
In the latter the collector job is more complex and time-
consuming due to the higher resource demand for record
processing in real time.
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Like TemplateIDs the CommonPropertiesIDs are generated
dynamically by the Exporting Process. The CommonPropertiesIDs
are only valid within the protocol stack. Hence a restart of the
exporting process may imply a renumbering of CommonProperiesIDs.
For this reason it is not recommended to use the
CommonPropertiesIds outside the protocol stack e.g. to store
them within a database. Outside the protocol stack there is
additional information needed to keep a non-ambiguous
association between the related Common Properties and Specific
Properties.
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.
If a Collection Process receives a CommonPropertiesID Withdraw
Record, the Collection Process MUST expire the related Common
Properties data.
If 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.
7.1 SCTP
When the SCTP association is reset, either gracefully or
abnormally, the Collecting Processes MUST delete all
commonPropertiesID values associated with that association.
7.2 UDP
The Collecting Process associates a lifetime with each
commonPropertiesID. The mapping of Data Records to Common
Properties uses the most recent Common Properties definition
associated to the specified commonPropertiesID. The lifetime of
the CommonPropertiesID ends on the receipt of a
CommonPropertiesID withdrawal record. If there is no flow
definition associated with that commonPropertiesID or the
lifetime of the flow definition has expired, no mapping is
possible. In this case the Collecting Process MAY store the
Specific Properties and await the retransmission or out-of-order
arrival of the Common Properties.
7.3 TCP
When the TCP connection is reset, either gracefully or
abnormally, the Collecting Processes MUST expire all
commonPropertiesID values corresponding to that connection.
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
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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.
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 cant 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.
10. Security Considerations
For the proposed use of the IPFIX protocol for bandwidth-saving
export the security considerations as for the IPFIX protocol
apply.
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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 14 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 14: 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 15):
- 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 15: Specific Properties Template
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
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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 16: Data Records reporting Common Properties
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 17 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 17: Data Record reporting Specific Properties
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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 18 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 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 [NOTE: to be included
in IPFIX-INFO], 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 18: 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 19 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)
- 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
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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 = 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 19: 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 20: Specific Properties
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 21 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
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- 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 1 |0| transportSourcePort = 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 |0|transportDestinationPort = 11|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Field Length = 2 | (Padding) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: 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 22 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.
Boschi, Mark, Claise Expires December 2006 [Page 25]
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 = 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 22: Example Packet Properties Template
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.
12. References
12.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC 2119,
March 1997
[IPFIX-PROTO] Benoit Claise et Al.: IPFIX Protocol
Specification, IETF draft work in progress
<draft-ietf-ipfix-protocol-22.txt>, April 2006
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[IPFIX-INFO] J. Quittek, S.Bryant, B.Claise, J. Meyer:
Information Model for IP Flow Information Export
Internet-draft work in progress <draft-ietf-ipfix-
info-12.txt>, September 2005
[PSAMP-PROTO] Benoit Claise: PSAMP Protocol Specification,
Internet Draft <draft-ietf-psamp-protocol-05.txt>,
March 2006
12.2 Informative References
[IPFIX-ARCH] Sadasivan, G., Brownlee, N., Claise, B., Quittek,
J., "Architecture Model for IP Flow Information
Export" draft-ietf-ipfix-arch-11.txt, May 2005
[IPFIX-AS] Zseby, T., Boschi, E., Brownlee, N., Claise, B.,
"IPFIX Applicability", draft-ietf-ipfix-as-06.txt,
May 2005
[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
[PSAMP-INFO] T. Dietz, F. Dressler, G. Carle, B. Claise,
"Information Model for Packet Sampling Exports",
draft-ietf-psamp-info-03.txt
[PSAMP-MIB] T. Dietz, B. Claise "Definitions of Managed Objects
for Packet Sampling" draft-ietf-psamp-mib-05.txt
[PSAMP-FMWK] D. Chiou, B. Claise, N. Duffield, A. Greenberg, M.
Grossglauser, P. Marimuthu, J. Rexford, G.
Sadasivan, "A Framework for Passive Packet
Measurement" draft-ietf-psamp-framework-10.txt
[RFC3917] Quittek, J., Zseby, T., Claise, B., Zander, S.,
"Requirements for IP Flow Information Export" RFC
3917, October 2004
13. 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 December 2006 [Page 27]
Reducing redundancy in IPFIX and PSAMP reports
Phone: +32 2 704 5622
Email: bclaise@cisco.com
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