IPFIX Working Group E. Boschi
Internet-Draft Hitachi Europe
Intended status: Informational L. Mark
Expires: September 1, 2007 Fraunhofer FOKUS
B. Claise
Cisco Systems, Inc.
February 28, 2007
Reducing Redundancy in IPFIX and PSAMP Reports
draft-ietf-ipfix-reducing-redundancy-03.txt
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Copyright (C) The IETF Trust (2007).
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.
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. IPFIX Documents Overview . . . . . . . . . . . . . . . . . 3
1.2. PSAMP Documents Overview . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Terminology Summary Table . . . . . . . . . . . . . . . . 8
2.2. IPFIX Flows versus PSAMP Packets . . . . . . . . . . . . . 9
3. Specifications for bandwidth saving information export . . . . 9
3.1. Problem Statement and High Level Solution . . . . . . . . 9
3.2. Data Reduction technique . . . . . . . . . . . . . . . . . 11
4. Transport Protocol Choice . . . . . . . . . . . . . . . . . . 12
4.1. PR-SCTP . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. UDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3. TCP . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5. commonPropertiesID Management . . . . . . . . . . . . . . . . 13
6. The Collecting Process Side . . . . . . . . . . . . . . . . . 14
6.1. UDP . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.2. TCP . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7. Advanced Techniques . . . . . . . . . . . . . . . . . . . . . 16
7.1. Multiple Data Reduction . . . . . . . . . . . . . . . . . 16
7.2. Cascading Common Properties . . . . . . . . . . . . . . . 19
8. Export and Evaluation Considerations . . . . . . . . . . . . . 19
8.1. Transport Protocol Choice . . . . . . . . . . . . . . . . 20
8.2. Reduced Size Encoding . . . . . . . . . . . . . . . . . . 20
8.3. Efficiency Gain . . . . . . . . . . . . . . . . . . . . . 20
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
10. Security Considerations . . . . . . . . . . . . . . . . . . . 21
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.1. Normative References . . . . . . . . . . . . . . . . . . . 22
12.2. Informative References . . . . . . . . . . . . . . . . . . 22
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 23
A.1. Per Flow Data Reduction . . . . . . . . . . . . . . . . . 23
A.2. Per Packet Data Reduction . . . . . . . . . . . . . . . . 27
A.3. commonPropertiesID Template Withdrawal Message . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31
Intellectual Property and Copyright Statements . . . . . . . . . . 32
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1. Introduction
The IPFIX working group has specified a protocol to export IP Flow
information [I-D.ietf-ipfix-protocol]. 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 the IPFIX Information Model [I-D.ietf-ipfix-protocol] or
registered with IANA.
Regardless of the fields content, flow records with common properties
export the same fields in every single data record. These common
properties may represent values common to a collection of flows or
packets, or values that are invariant over time. Note that the
common properties don't represent the list of flow keys, which are
used to define a flow definition: however, the common properties may
contain some of the flow keys. 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.
1.1. IPFIX Documents Overview
The IPFIX Protocol [I-D.ietf-ipfix-protocol] provides network
administrators with access to IP flow information. The architecture
for the export of measured IP flow information out of an IPFIX
exporting process to a collecting process is defined in the IPFIX
Architecture [I-D.ietf-ipfix-architecture], per the requirements
defined in RFC 3917 [RFC3917]. The IPFIX Architecture
[I-D.ietf-ipfix-architecture] 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 the IPFIX
Information Model [I-D.ietf-ipfix-info]. Finally the IPFIX
Applicability Statement [I-D.ietf-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
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relates to other architectures and frameworks.
1.2. PSAMP Documents Overview
The document "A Framework for Packet Selection and Reporting"
[I-D.ietf-psamp-framework], 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"
[I-D.ietf-psamp-sample-tech]. The PSAMP protocol
[I-D.ietf-psamp-protocol] 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 [I-D.ietf-psamp-info]. Finally
[I-D.ietf-psamp-mib] describes the PSAMP Management Information Base.
2. Terminology
The terms in this section are in line with the IPFIX terminology
section in the IPFIX [I-D.ietf-ipfix-protocol], and PSAMP
[I-D.ietf-psamp-protocol] protocol specifications. Note that this
document selected the IPFIX definition of the term Exporting Process
[I-D.ietf-ipfix-protocol], as this definition is more generic than
the PSAMP definition [I-D.ietf-psamp-protocol].
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
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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 [RFC3550])
2. one or more characteristics of the packet itself (e.g. number
of MPLS labels, etc...)
3. one or more of fields derived from packet treatment (e.g. next
hop IP address, the output interface, etc...)
A packet is defined 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.
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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: 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.
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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
[I-D.ietf-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:
1. the Packet Content;
2. information derived from the packet's treatment at the
Observation Point;
3. 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.
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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.
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.
commonPropertiesID: The commonPropertiesID is an identifier of a
set of common properties that is locally unique per Observation
Domain and Transport Session. Typically, this Information Element
is used to link to information reported in separate Data Records.
See the IPFIX information model [I-D.ietf-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.
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].
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) | |
+------------------+--------------------+------------------------+
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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 the PSAMP protocol specification
[I-D.ietf-psamp-protocol], 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. Specifications for bandwidth saving information export
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 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. Therefore, the method described in this
document is also applicable to per packet data reduction, e.g. for
export of One Way Delay (OWD) measurements (see Appendix), trajectory
sampling, etc.
3.1. Problem Statement and High Level Solution
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
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information.
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <Flow1 information> |
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <Flow2 information> |
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <Flow3 information> |
+----------------+-------------+---------------------------+
| sourceAddressA | sourcePortA | <Flow4 information> |
+----------------+-------------+---------------------------+
| ... | ... | ... |
+----------------+-------------+---------------------------+
Figure 2: Common and Specific Properties exported together
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 |
+------------------------+-----------------+-------------+
| ... | ... | ... |
+------------------------+-----------------+-------------+
+------------------------+---------------------------+
| index for properties A | <Flow1 information> |
+------------------------+---------------------------+
| index for properties A | <Flow2 information> |
+------------------------+---------------------------+
| index for properties A | <Flow3 information> |
+------------------------+---------------------------+
| index for properties A | <Flow4 information> |
+------------------------+---------------------------+
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Figure 3: Common and Specific Properties exported separately
This unique export of the Common Properties results in a decrease of
the bandwidth requirements for the path between the Exporter and the
Collector.
3.2. Data Reduction technique
The IPFIX protocol [I-D.ietf-ipfix-protocol] 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 the IPFIX protocol
[I-D.ietf-ipfix-protocol].
As explained in Figure 4, 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. Like Template
Records, they MUST be sent only once per SCTP association or TCP
connection, and MUST be sent reliably via SCTP if SCTP is the
transport protocol. 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
[I-D.ietf-ipfix-info]. The commonPropertiesID MUST be exported as
the scope in the Options Template Record, and also exported in the
associated Template Record.
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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 4: Template Record and Data Record dependencies
From the IPFIX protocol, there are no differences between the per
Flow or per packet data reduction, except maybe the terminology where
the Specific Properties could be called packet Specific Properties in
the previous figure.
4. Transport Protocol Choice
This document follows the IPFIX transport protocol specifications
defined in the IPFIX protocol [I-D.ietf-ipfix-protocol]. 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.
4.1. 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 Data Records MUST be sent reliably.
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4.2. 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 (refresh timeout) is 10
minutes.
The Exporting Process SHOULD transmit the Common Properties
definition in advance of any Data Record that use these Common
Properties, to help ensure that the Collector has the Common
Properties definition before receiving the first associated Data
Record.
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
Section 6.1) has expired.
4.3. 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.
5. 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 Exporter MAY use the same
commonPropertiesID value to refer to different sets of Common
Properties.
The commonPropertiesID values MAY be assigned sequentially, but it is
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 active sets of Common Properties, per Observation
Domain and per Transport Session.
commonPropertiesIDs that are not used anymore SHOULD be withdrawn.
The Common Properties ID withdrawal message is a Data Record defined
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by an Option Template consisting of only one scope field namely the
commonPropertiesID (with a type of 137 [I-D.ietf-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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
6. 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 Data 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 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 SHOULD store the Specific Properties Data Record
and await the retransmission or out-of-order arrival of the Common
Properties Data Record.
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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 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 interpreting Data Records referring to
those Common Properties. The receipt of Data Records referring to
Common Properties that have been withdrawn MUST be ignored and SHOULD
be logged by the Collecting Process.
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.
6.1. 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
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 definition that differs from the
previous definition, the Collecting Process SHOULD log a warning and
replace the previous received Common Property with the new one. The
Common Property lifetime at the Collecting Process MUST be at least 3
times higher than the refresh timeout of the Template used to export
the Common Property definition, configured on the Exporting Process.
The Collecting Process SHOULD accept Data Records without the
associated Common Properties required to decode the Data Record. If
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the Common Properties have not been received at the time Data Records
are received, the Collecting Process SHOULD store the Data Records
for a short period of time and decode them after the Common
Properties 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.
6.2. TCP
When the TCP connection is reset, either gracefully or abnormally,
the Collecting Processes MUST delete all commonPropertiesID values
and associated Common Properties data corresponding to that
connection.
If a Collection Process receives a commonPropertiesID Withdraw
message, the Collection Process MUST expire the related Common
Properties data.
7. Advanced Techniques
7.1. 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.
When sets of Common Properties are identified in the data, it may be
found that there is more than one set of non-overlapping properties.
Note that in the case of multiple Common Properties in one Data
Record, 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 6 shows how this
information is repeated with classical IPFIX export in several Flow
Records.
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+--------+--------+---------+---------+---------------------+
|srcAddrA|srcPortA|destAddrB|destPortB| <Flow1 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrA|srcPortA|destAddrC|destPortC| <Flow2 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrD|srcPortD|destAddrB|destPortB| <Flow3 information> |
+--------+--------+---------+---------+---------------------+
|srcAddrD|srcPortD|destAddrC|destPortC| <Flow4 information> |
+--------+--------+---------+---------+---------------------+
| ... | ... | ... | ... | ... |
+--------+--------+---------+---------+---------------------+
Figure 6: Common and Specific Properties exported together
Besides that other sets of Properties might be repeated as well (e.g.
properties C and D in the figure above).
We can separate the Common Properties into the properties A composed
of sourceAddressA and sourcePortA, properties D composed of
sourceAddressD and sourcePortD, and into the properties B composed of
destinationAddressB and destinationPortB and properties C composed of
destinationAddressC and destinationPortC,. These four records can be
expanded to four combinations of Data Records to reduce redundancy
without the need to define four complete sets of Common Properties
(see the figure below). The more Common Properties sets are defined,
the more combinations are available.
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+-------------------+-----------------+-------------+
| index for prop. A | sourceAddressA | sourcePortA |
+-------------------+-----------------+-------------+
| index for prop. D | sourceAddressD | sourcePortD |
+-------------------+-----------------+-------------+
+-------------------+---------------------+------------------+
| index for prop. B | destinationAddressB | destinationPortB |
+-------------------+---------------------+------------------+
| index for prop. C | destinationAddressC | destinationPortC |
+-------------------+---------------------+------------------+
+-----------------+-----------------+-----------------------+
|index for prop. A|index for prop. B| <Flow1 information> |
+-----------------+-----------------+-----------------------+
|index for prop. A|index for prop. C| <Flow2 information> |
+-----------------+-----------------+-----------------------+
|index for prop. D|index for prop. B| <Flow3 information> |
+-----------------+-----------------+-----------------------+
|index for prop. D|index for prop. C| <Flow4 information> |
+-----------------+-----------------+-----------------------+
Multiple Common (above) and Specific Properties (below) exported
separately
The advantage of the multiple Common Properties is that the objective
of reducing the bandwidth is met while the number of indexes is kept
to a minimum. Defining an extra index for all records would not
bring to save bandwidth in the case of Figure 6 and is generally a
less efficient solution.
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 Figure 8.
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+--------------------------- + +---------------------+
| 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 8: Multiple Data Reduction
7.2. Cascading Common Properties
An Exporting Process MUST NOT export any set of Common Properties
which contains, either directly or via other cascaded Common
Properties, references to itself in its own definition (i.e., a
circular definition). When the Collecting Process receives Common
Properties that reference other Common Properties, it MUST resolve
the references to Common Properties. If the Common Properties aren't
available 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 Common Properties are received.
If the Collecting Process could not decode a cascading Common
Properties definition because the referenced Common Properties are
not available before the short period of time, then the Collecting
Process SHOULD log the error.
If the Collecting Process could not decode a cascading Common
Properties definition because it detects a circular definition, then
the Collecting Process SHOULD log the error.
Information Element ordering MUST be preserved when creating and
expanding Common Properties.
8. Export and Evaluation Considerations
The objective of the method specified in this document is the
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reduction in the amount of measurement data that has to be
transferred from the Exporter to the Collector. Note that the
efficiency of this method may vary, as discussed in this section. In
addition there might be less storage capacity required at the
Collector side if the Collector decides to store the Data Records as
they arrive, without reconstructing the initial Flow Record.
On the other hand, this method requires additional resources on both
the Exporter and the Collector. The Exporter has to manage Common
Properties information and to assign commonPropertiesId values. 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-PR with the reliable mode 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 and
might even increase the amount of exported data if the length of the
commonPropertiesID field is not shorter than the length of the
replaced fields.
In cases where the range of the commonPropertiesID can be restricted,
it is RECOMMENDED to apply reduced-size encoding to the
commonPropertiesID, to achieve a further bandwidth efficiency gain.
8.3. Efficiency Gain
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 and would be directly
proportional to the re-use of the defined commonPropertiesID values
(In other words, the more we re-use a commonPropertiesID value, the
better the efficiency gain), with a theoretical limit where all the
Data Records would use a single commonPropertiesID. While the
Exporting Process can evaluate the direct gain for the Flow Records
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to be exported, it cannot 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.
Note that this technique might even lead to an increase in bandwidth
usage under certain conditions. Taking into account the overhead of
exporting the commonPropertiesID values, if the commonPropertiesID
values are not used in future Data Records, this technique would
actually increase the export bandwidth. A typical case would be the
assignments of Common Properties based on past observed traffic,
hoping that future Flows would contain the same characteristics.
The efficiency gain depends also on the difference between the length
of the replaced fields and the length of the commonPropertiesID. The
shorter is the length of commonPropertiesID with respect to the total
length of the Common Properties fields, the bigger is the gain.
The example in section Appendix A.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 26
percent.
9. IANA Considerations
This document has no actions for IANA.
10. Security Considerations
The same security considerations as for the IPFIX Protocol
[I-D.ietf-ipfix-protocol] apply.
11. Acknowledgments
The authors would like to thank Guido Pohl for initiating this work
and for his contribution to early versions of this document. Thanks
also to Andrew Johnson, Gehrard Muenz, Brian Trammell and Paul Aitken
for their comments and feedback.
12. References
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12.1. Normative References
[I-D.ietf-ipfix-protocol]
Claise, B., "Specification of the IPFIX Protocol for the
Exchange", draft-ietf-ipfix-protocol-24 (work in
progress), November 2006.
[I-D.ietf-ipfix-info]
Quittek, J., "Information Model for IP Flow Information
Export", draft-ietf-ipfix-info-15 (work in progress),
February 2007.
[I-D.ietf-psamp-protocol]
Claise, B., "Packet Sampling (PSAMP) Protocol
Specifications", draft-ietf-psamp-protocol-07 (work in
progress), October 2006.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
12.2. Informative References
[I-D.ietf-ipfix-as]
Zseby, T., "IPFIX Applicability", draft-ietf-ipfix-as-11
(work in progress), February 2007.
[I-D.ietf-ipfix-architecture]
Sadasivan, G., "Architecture for IP Flow Information
Export", draft-ietf-ipfix-architecture-12 (work in
progress), September 2006.
[I-D.ietf-psamp-info]
Dietz, T., "Information Model for Packet Sampling
Exports", draft-ietf-psamp-info-05 (work in progress),
October 2006.
[I-D.ietf-psamp-sample-tech]
Zseby, T., "Sampling and Filtering Techniques for IP
Packet Selection", draft-ietf-psamp-sample-tech-07 (work
in progress), July 2005.
[I-D.ietf-psamp-mib]
Dietz, T. and B. Claise, "Definitions of Managed Objects
for Packet Sampling", draft-ietf-psamp-mib-06 (work in
progress), June 2006.
[I-D.ietf-psamp-framework]
Duffield, N., "A Framework for Packet Selection and
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Reporting", draft-ietf-psamp-framework-10 (work in
progress), January 2005.
[RFC2960] Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
Zhang, L., and V. Paxson, "Stream Control Transmission
Protocol", RFC 2960, October 2000.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander,
"Requirements for IP Flow Information Export (IPFIX)",
RFC 3917, October 2004.
Appendix A. Examples
A.1. Per Flow 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 |2001:DB8:80AD:5800:0058:0800:2023:1D71 | 80 | 30 | 6000
| | | |
A |2001:DB8:80AD:5800:0058:0800:2023:1D71 | 80 | 50 | 9500
| | | |
B |2001:DB8:80AD:5800:0058:00AA:00B7:AF2B | 1932 | 60 | 8000
| | | |
A |2001:DB8:80AD:5800:0058:0800:2023:1D71 | 80 | 40 | 6500
| | | |
A |2001:DB8:80AD:5800:0058:0800:2023:1D71 | 80 | 60 | 9500
| | | |
B |2001:DB8:80AD: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
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contains the following Information Elements:
o Scope: commonPropertiesID in [I-D.ietf-ipfix-info], with a type of
137 and a length of 8 octets.
o The destination IPv6 address: destinationIPv6Address in
[I-D.ietf-ipfix-info], with a type of 28 and a length of 16
octets.
o The destination port: destinationTransportPort in
[I-D.ietf-ipfix-info], with a type of 11, and a length of 2 octets
Figure 10 shows the Option template defining the Common Properties
with commonPropertiesID as scope:
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 10: Common Properties Option Template
The Specific Properties Template consists of the information not
contained in the Option Templates, i.e. Flow specific information, n
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 11):
o commonPropertiesID with a length of 8 octets
o The number of packets of the Flow: inPacketDeltaCount in
[I-D.ietf-ipfix-info], with a length of 4 octets.
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o The number of octets of the Flow: inOctetDeltaCount in
[I-D.ietf-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 = 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| commonPropertiesID = 137 | Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inPacketDeltaCount = 2 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| inOctetDeltaCount = 1 | Field Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: 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 | 2001:DB8:80AD:5800:0058:0800:2023:1D71 | 80
| |
102 | 2001:DB8:80AD:5800:0058:00AA:00B7:AF2B | 1932
The Data Records reporting the Common Properties will look like:
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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 = 257 | Length = 60 octets |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- 101 -+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- -+
| |
+- 2001:DB8:80AD:5800:0058:0800:2023:1D71 -+
| |
+- -+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 80 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- -+
| 102 |
+- -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+
| |
+- -+
| 2001:DB8:80AD:5800:0058:00AA:00B7:AF2B |
+- -+
| |
+- -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | 1932 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: 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
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Figure 15 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 15: Data Records reporting Common Properties
A.2. Per Packet Data Reduction
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 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.
The Templates required for exporting measurement data of this kind
are illustrated in the figures below. Figure 16 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:
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o The source IPv4 Address: sourceIPv4Address in
[I-D.ietf-ipfix-info], with a type of 8 and a length of 4 octets.
o The destination IPv4 Address: destinationIPv4Address in
[I-D.ietf-ipfix-info], with a type of 12 and a length of 4 octets.
o The Class of Service field: ClassOfServiceIPv4 in
[I-D.ietf-ipfix-info], with a type of 5 and a length of 1 octet
o The Protocol Identifier: protocolIdentifier in
[I-D.ietf-ipfix-info], with a type of 4 and a length of 1 octet
o The source port: sourceTransportPort in [I-D.ietf-ipfix-info],
with a type of 7 and a length of 2 octets.
o The destination port: destinationTransportPort in
[I-D.ietf-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 = 137 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: Example Flow Properties Template
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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 17 displays the template with the packet properties. In this
example we export the following Information Elements:
o commonPropertiesID. In this case reduced size encoding is used,
and the Information Element is declared with a length of 4 octets
instead of 8.
o The packet timestamp: observationTimeMilliseconds in the PSAMP
Information Model [I-D.ietf-psamp-info], with a type of 323 and a
length of 8 octets.
o digestHashValue in the PSAMP Information Model
[I-D.ietf-psamp-info], with a type of 326 and a length of 8 octets
o The packet length: ipTotalLength in the IPFIX Information Model
[I-D.ietf-ipfix-info], with a type of 224 and a length of 8 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| observationTimeMillis.= 323 | Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| digestHashValue = 326 | Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| ipTotalLength = 224 | Field Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: 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
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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 38 bytes have to be transferred (sourceAddressV4=4,
destinationAddressV4=4, classOfServiceV4=1, protocolIdentifier=1,
sourceTransportPort=2, destionationTransportPort=2,
observationTimeMilliseconds=8, digestHashValue=8, ipTotalLength=8).
Without considering the IPFIX protocol overhead a Flow of 1000
packets produces 38000 bytes of measurement data. Using the proposed
optimization each packet produces an export of only 28 bytes
(observationTimeMilliseconds=8, digestHashValue=8, ipTotalLength=8,
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 28018 bytes. This is a decrease of more
than 26 percent.
A.3. commonPropertiesID Template Withdrawal Message
This section shows an example commonPropertiesID Withdrawal message.
Figure 18 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 18: example commonPropertiesID withdrawal template
Figure 19 shows the Option Data Record withdrawing commonPropertiesID
N:
Boschi, et al. Expires September 1, 2007 [Page 30]
Internet-Draft Reducing Redundancy February 2007
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 19: commonPropertiesID withdrawal record, withdrawing
commonPropertiesID N
Authors' Addresses
Elisa Boschi
Hitachi Europe SAS
Immeuble Le Theleme
1503 Route les Dolines
06560 Valbonne
France
Phone: +33 4 89874100
Email: elisa.boschi@hitachi-eu.com
Lutz Mark
Fraunhofer FOKUS
Kaiserin Augusta Allee 31
10589 Berlin
Germany
Phone: +49 30 34637306
Email: mark@fokus.fraunhofer.de
Benoit Claise
Cisco Systems
De Kleetlaan 6a b1
Diegem 1813
Belgium
Phone: +32 2 704 5622
Email: bclaise@cisco.com
Boschi, et al. Expires September 1, 2007 [Page 31]
Internet-Draft Reducing Redundancy February 2007
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Boschi, et al. Expires September 1, 2007 [Page 32]
