Internet DRAFT - draft-ietf-ipfix-flow-selection-tech
draft-ietf-ipfix-flow-selection-tech
Internet Engineering Task Force S. D'Antonio
Internet-Draft University of Napoli
Intended status: Standards Track "Parthenope"
Expires: December 1, 2013 T. Zseby
CAIDA/FhG FOKUS
C. Henke
Tektronix Communication Berlin
L. Peluso
University of Napoli
May 30, 2013
Flow Selection Techniques
draft-ietf-ipfix-flow-selection-tech-18.txt
Abstract
Intermediate Flow Selection Process is the process of selecting a
subset of Flows from all observed Flows. The Intermediate Flow
Selection Process may be located at an IPFIX Exporter, Collector, or
within an IPFIX Mediator. It reduces the effort of post-processing
Flow data and transferring Flow Records. This document describes
motivations for using the Intermediate Flow Selection process and
presents Intermediate Flow Selection techniques. It provides an
information model for configuring Intermediate Flow Selection Process
techniques and discusses what information about an Intermediate Flow
Selection Process should be exported.
Requirements Language
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].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on December 1, 2013.
Copyright Notice
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Table of Contents
1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Difference between Intermediate Flow Selection Process and
Packet Selection . . . . . . . . . . . . . . . . . . . . . . . 8
4. Difference between Intermediate Flow Selection Process and
Intermediate Selection Process . . . . . . . . . . . . . . . . 9
5. Intermediate Flow Selection Process within the IPFIX
Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Intermediate Flow Selection Process in the Metering
Process . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2. Intermediate Flow Selection Process in the Exporting
Process . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.3. Intermediate Flow Selection Process as a function of
the IPFIX Mediator . . . . . . . . . . . . . . . . . . . . 12
6. Intermediate Flow Selection Process Techniques . . . . . . . . 12
6.1. Flow Filtering . . . . . . . . . . . . . . . . . . . . . . 13
6.1.1. Property Match Filtering . . . . . . . . . . . . . . . 13
6.1.2. Hash-based Flow Filtering . . . . . . . . . . . . . . 14
6.2. Flow Sampling . . . . . . . . . . . . . . . . . . . . . . 14
6.2.1. Systematic sampling . . . . . . . . . . . . . . . . . 14
6.2.2. Random Sampling . . . . . . . . . . . . . . . . . . . 15
6.3. Flow-state Dependent Intermediate Flow Selection
Process . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.4. Flow-state Dependent Packet Selection . . . . . . . . . . 16
7. Configuration of Intermediate Flow Selection Process
Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. Intermediate Flow Selection Process Parameters . . . . . . 18
7.2. Description of Flow-state Dependent Packet Selection . . . 20
8. Information Model for Intermediate Flow Selection Process
Configuration and Reporting . . . . . . . . . . . . . . . . . 21
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
9.1. Registration of Information Elements . . . . . . . . . . . 22
9.1.1. flowSelectorAlgorithm . . . . . . . . . . . . . . . . 22
9.1.2. flowSelectedOctetDeltaCount . . . . . . . . . . . . . 24
9.1.3. flowSelectedPacketDeltaCount . . . . . . . . . . . . . 25
9.1.4. flowSelectedFlowDeltaCount . . . . . . . . . . . . . . 25
9.1.5. selectorIDTotalFlowsObserved . . . . . . . . . . . . . 25
9.1.6. selectorIDTotalFlowsSelected . . . . . . . . . . . . . 26
9.1.7. samplingFlowInterval . . . . . . . . . . . . . . . . . 26
9.1.8. samplingFlowSpacing . . . . . . . . . . . . . . . . . 27
9.1.9. flowSamplingTimeInterval . . . . . . . . . . . . . . . 27
9.1.10. flowSamplingTimeSpacing . . . . . . . . . . . . . . . 27
9.1.11. hashFlowDomain . . . . . . . . . . . . . . . . . . . . 28
9.2. Registration of Object Identifier . . . . . . . . . . . . 28
10. Security and Privacy Considerations . . . . . . . . . . . . . 29
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30
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12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 31
12.1. Normative References . . . . . . . . . . . . . . . . . . . 31
12.2. Informative References . . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 32
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1. Scope
This document describes Intermediate Flow Selection Process
techniques for network traffic measurements. A Flow is defined as a
set of packets with common properties as described in
[I-D.ietf-ipfix-protocol-rfc5101bis]. An Intermediate Flow Selection
Process can be executed to limit the resource demands for capturing,
storing, exporting and post-processing of Flow Records. It also can
be used to select a particular set of Flows that are of interest to a
specific application. This document provides a categorization of
Intermediate Flow Selection Process techniques and describes
configuration and reporting parameters for them.
This document also addresses configuration and reporting parameters
for Flow-state Dependent Packet Selection as described in [RFC5475],
although this technique is categorized as packet selection. The
reason is that Flow-state Dependent Packet Selection techniques often
aim at the reduction of resources for Flow capturing and Flow
processing. Furthermore, these techniques were only briefly
discussed in [RFC5475]. Therefore configuration and reporting
considerations for Flow-state Dependent Packet Selection techniques
have been included in this document.
2. Terminology
This document is consistent with the terminology introduced in
[I-D.ietf-ipfix-protocol-rfc5101bis], [RFC5470], [RFC5475] and
[RFC3917]. As in [I-D.ietf-ipfix-protocol-rfc5101bis] and [RFC5476],
the first letter of each IPFIX-specific and PSAMP-specific term is
capitalized along with the Intermediate Flow Selection Process
specific terms defined here.
* Packet Classification
Packet Classification is a process by which packets are mapped to
specific Flow Records based on packet properties or external
properties (e.g. interface). The properties (e.g. header
information, packet content, AS number) make up the Flow Key. In
case a Flow Record for a specific Flow Key value already exists
the Flow Record is updated, otherwise a new Flow Record is
created.
* Intermediate Flow Selection Process
An Intermediate Flow Selection Process is an Intermediate Process
as in [RFC6183] that takes Flow Records as its input and selects a
subset of this set as its output. Intermediate Flow Selection
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Process is a more general concept than Intermediate Selection
Process as defined in [RFC6183]. While an Intermediate Selection
Process selects Flow Records from a sequence based upon criteria-
evaluated Flow Record values and passes only those Flow Records
that match the criteria, an Intermediate Flow Selection Process
selects Flow Records using selection criteria applicable to a
larger set of Flow characteristics and information.
* Flow Cache
A Flow Cache is the set of Flow Records.
* Flow Selection State
An Intermediate Flow Selection Process maintains state information
for use by the Flow Selector. At a given time, the Flow Selection
State may depend on Flows and packets observed at and before that
time, as well as other variables. Examples include:
(i) sequence number of packets and accounted Flow Records;
(ii) number of selected Flows;
(iii) number of observed Flows;
(iv) current Flow Cache occupancy;
(v) Flow specific counters, lower and upper bounds;
(vi) Intermediate Flow Selection Process timeout intervals.
* Flow Selector
A Flow Selector defines the action of an Intermediate Flow
Selection Process on a single Flow of its input. The Flow
Selector can make use of the following information in order to
establish whether a Flow has to be selected or not:
(i) the content of the Flow Record;
(ii) any state information related to the Metering Process or
Exporting Process;
(iii) any Flow Selection State that may be maintained by the
Intermediate Flow Selection Process.
* Complete Flow
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A Complete Flow consists of all the packets that enter the
Intermediate Flow Selection Process within the Flow time-out
interval, and which belong to the same Flow as defined by the Flow
definition in [RFC5470]. For this definition only packets that
arrive at the Intermediate Flow Selection Process are considered.
* Flow Position
Flow Position is the position of a Flow Record within the Flow
Cache.
* Flow Filtering
Flow Filtering selects flows based on a deterministic function on
the Flow Record content, Flow Selection State, external properties
(e.g. ingress interface) or external events (e.g violated Access
Control List). If the relevant parts of the Flow Record content
can already be observed at packet level (e.g. Flow Keys from
packet header fields) Flow Filtering can be performed at packet
level by Property Match Filtering as described in [RFC5475].
* Hash-based Flow Filtering
Hash-based Flow Filtering is a deterministic Flow filter function
that selects flows based on a Hash Function. The Hash Function is
calculated over parts of the Flow Record content or external
properties which are called the Hash Domain. If the hash value
falls into a predefined Hash Selection Range the Flow is selected.
* Flow-state Dependent Intermediate Flow Selection Process
Flow-state Dependent Intermediate Flow Selection Process is a
selection function that selects or drops Flows based on the
current Flow Selection State. The selection can be either
deterministic, random or non-uniform random.
* Flow-state Dependent Packet Selection
Flow-state Dependent Packet Selection is a selection function that
selects or drops packets based on the current Flow Selection
State. The selection can be either deterministic, random or non-
uniform random. Flow-state Dependent Packet Selection can be used
to prefer the selection of packets belonging to specific Flows.
For example the selection probability of packets belonging to
Flows that are already within the Flow Cache may be higher than
for packets that have not been recorded yet.
* Flow Sampling
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Flow Sampling selects flows based on Flow Record sequence or
arrival times (e.g. entry in Flow Cache, arrival time at Exporter
or Mediator). The selection can be systematic (e.g. every n-th
Flow) or based on a random function (e.g. select each Flow Record
with probability p, or randomly select n out of N Flow Records).
3. Difference between Intermediate Flow Selection Process and Packet
Selection
Intermediate Flow Selection Process differs from packet selection
described in [RFC5475]. Packet selection techniques consider packets
as the basic element and the parent population consists of all
packets observed at an Observation Point. In contrast to this the
basic elements in Flow selection are the Flows. The parent
population consists of all observed Flows and the Intermediate Flow
Selection Process operates on the Flows. The major characteristics
of Intermediate Flow Selection Process are the following:
- Intermediate Flow Selection Process takes Flows as basic
elements. For packet selection, packets are considered as
basic elements.
- Intermediate Flow Selection Process typically takes place
after Packet Classification, because the classification rules
determine to which Flow a packet belongs. Intermediate Flow
Selection Process can be performed before Packet
Classification. In that case Intermediate Flow Selection
Process is based on the Flow Key (also on a hash value over
the Flow Key), but not based on characteristics that are only
available after Packet Classification (e.g. Flow size, Flow
duration). Packet selection can be applied before and after
Packet Classification. As an example, packet selection
before Packet Classification can be random packet selection
whereas packet selection after Packet Classification can be
Flow-state Dependent Packet Selection (as described in
[RFC5475])
- Intermediate Flow Selection Process operates on Complete
Flows. That means that after the Intermediate Flow Selection
Process either all packets of the Flow are kept or all
packets of the Flow are discarded. That means that if the
Intermediate Flow Selection Process is preceded by a packet
selection process the Complete Flow consists only of the
packets that were not discarded during the packet selection.
There are some techniques that are difficult to unambiguously
categorize into one of the categories. Here some guidance is given
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on how to categorize such techniques:
- Techniques that can be considered as both packet selection
and Intermediate Flow Selection Process: some packet
selection techniques result in the selection of Complete
Flows and therefore can be considered as packet selection or
as Intermediate Flow Selection Process at the same time. An
example is Property Match Filtering of all packets to a
specific destination address. If Flows are defined based on
destination addresses, such a packet selection also results
in a Intermediate Flow Selection Process and can be
considered as packet selection or Intermediate Flow Selection
Process.
- Flow-state Dependent Packet Selection: there exist techniques
that select packets based on the Flow state, e.g. based on
the number of already observed packets belonging to the Flow.
Examples of these techniques from the literature are "Sample
and Hold" [EsVa01] "Fast Filtered Sampling" [MSZC10] or the
"Sticky Sampling" algorithm presented in [MaMo02]. Such
techniques can be used to influence which Flows are captured
(e.g. increase the selection of packets belonging to large
Flows) and reduce the number of Flows that need to be stored
in the Flow Cache. Nevertheless, such techniques do not
necessarily select Complete Flows, because they do not ensure
that all packets of a selected Flow are captured. Therefore
Flow-state Dependent Packet Selection techniques that do not
ensure that either all or no packets of a Flow are selected
strictly speaking have to be considered as packet selection
techniques and not as Intermediate Flow Selection Process
techniques.
4. Difference between Intermediate Flow Selection Process and
Intermediate Selection Process
Intermediate Flow Selection Process differs from Intermediate
Selection Process since Intermediate Flow Selection Process uses
selection criteria that apply to a larger set of Flow information and
properties than those used by Intermediate Selection Process. The
typical function of an Intermediate Selection Process is Property
Match Filtering that selects a Flow Record if the value of a specific
field in the Flow Record matches a configured value or falls within a
configured range. This means that the selection criteria used by an
Intermediate Selection Process are evaluated only on Flow Record
values. An Intermediate Flow Selection Process makes its decision on
whether a Flow has to be selected or not by taking into account not
only information related to the content of the Flow Record, but also
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any Flow Selection State information or variable that can be used to
select Flows in order to meet applications requirements or resource
constraints (e.g. Flow Cache occupancy, export link capacity).
Examples are as flow counters, Intermediate Flow Selection Process
timeout intervals, and Flow Record time information.
5. Intermediate Flow Selection Process within the IPFIX Architecture
An Intermediate Flow Selection Process can be deployed at any of
three places within the IPFIX architecture. As shown in Figure 1
Intermediate Flow Selection Process can occur
1. in the Metering Process at the IPFIX Exporter
2. in the Exporting Process at the Collector
3. within a Mediator
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+===========================================+
| IPFIX Exporter +----------------+ |
| | Metering Proc. | |
| +-----------------+ +----------------+ |
| | Metering | | Intermediate | |
| | Process | or | Flow Selection | |
| | | | Process | |
| +-----------------+----+----------------+ |
| | Exporting Process | |
| +----|-------------------------------|--+ |
+======|===============================|====+
| |
| |
+======|========================+ |
| | Mediator | |
| +-V-------------------+ | |
| | Collecting Process | | |
| +---------------------+ | |
| | Intermediate Flow | | |
| | Selection Process | | |
| +---------------------+ | |
| | Exporting Process | | |
| +-|-------------------+ | |
+======|========================+ |
| |
| |
+======|===============================|=====+
| | Collector | |
| +----V-------------------------------V-+ |
| | Collecting Process | |
| +--------------------------------------+ |
| | Intermediate Flow Selection Process | |
| +--------------------------------------+ |
| | Exporting Process | |
| +------------------------------|-------+ |
+================================|===========+
|
|
V
+------------------+
| IPFIX |
+------------------+
Figure 1: Potential Intermediate Flow Selection Process locations
In contrast to packet selection, Intermediate Flow Selection Process
is always applied after the packets are classified into Flows.
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5.1. Intermediate Flow Selection Process in the Metering Process
Intermediate Flow Selection Process in the Metering process uses
packet information to update the Flow Records in the Flow Cache.
Intermediate Flow Selection Process before Packet Classification can
be based on the Flow Key (also on a hash value over the Flow Key),
but not based on characteristics that are only available after Packet
Classification (e.g. Flow size, Flow duration). An Intermediate
Flow Selection Process is here applied to reduce resources for all
succeeding processes or to select specific Flows of interest in case
such Flow characteristics are already observable at packet level
(e.g. Flows to specific IP addresses). In contrast, Flow-state
Dependent Packet Selection is a packet selection technique, because
it does not necessarily select Complete Flows.
5.2. Intermediate Flow Selection Process in the Exporting Process
Intermediate Flow Selection Process in the Exporting Process works on
Flow Records. An Intermediate Flow Selection Process in the
Exporting Process can therefore depend on Flow characteristics that
are only visible after the classification of packets, such as Flow
size and Flow duration. The Exporting Process may implement policies
for exporting only a subset of the Flow Records which have been
stored in the system memory in order to unload Flow export and Flow
post-processing. An Intermediate Flow Selection Process in the
Exporting Process may select only the subset of Flow Records which
are of interest to the users application, or select only as many Flow
Records as can be handled by the available resources (e.g. limited
export link capacity).
5.3. Intermediate Flow Selection Process as a function of the IPFIX
Mediator
As shown in Figure 1, Intermediate Flow Selection Process can be
performed within an IPFIX Mediator [RFC6183]. The Intermediate Flow
Selection Process takes Flow Record stream as its input and selects
Flow Records from a sequence based upon criteria-evaluated record
values. The Intermediate Flow Selection Process can again apply an
Intermediate Flow Selection Process technique to obtain Flows of
interest to the application. Further, the Intermediate Flow
Selection Process can base its selection decision on the correlation
of data from different IPFIX Exporters, e.g. by only selecting Flows
that were at least recorded on two IPFIX Exporters.
6. Intermediate Flow Selection Process Techniques
An Intermediate Flow Selection Process technique selects either all
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or none of the packets of a Flow, otherwise the technique has to be
considered as packet selection. A difference is recognized between
Flow Filtering and Flow Sampling.
6.1. Flow Filtering
Flow Filtering is a deterministic function on the IPFIX Flow Record
content. If the relevant Flow characteristics are already observable
at packet level (e.g. Flow Keys), Flow Filtering can be applied
before aggregation at packet level. In order to be compliant with
IPFIX, at least one of this document's Flow Filtering schemes MUST be
implemented.
6.1.1. Property Match Filtering
Property Match Filtering is performed similarly to Property Match
Filtering for packet selection described in [RFC5475]. The
difference is that, instead of packet fields, Flow Record fields are
here used to derive the selection decision. Property Match Filtering
is used to select a specific subset of the Flows that are of interest
to a particular application (e.g. all Flows to a specific
destination, all large Flows, etc.). Properties on which the
filtering is based can be Flow Keys, Flow Timestamps, or Per-Flow
Counters described in [RFC5102]. Examples are the Flow size in
bytes, the number of packets in the Flow, the observation time of the
first or last packet, or the maximum packet length. An example of
Property Match Filtering is to select Flows with more than a
threshold number of observed octets. The selection criteria can be a
specific value, a set of specific values, or an interval. For
example, a Flow is selected if destinationIPv4Address and the total
number of packets of the Flow equal two predefined values. An
Intermediate Flow Selection Process using Property Match Filtering in
the Metering Process relies on properties that are observable at the
packet level (e.g. Flow Key). For example, a Flow is selected if
sourceIPv4Address and sourceIPv4PrefixLength equal, respectively, two
specific values.
An Intermediate Flow Selection Process using Property Match Filtering
in the Exporting Process is based on properties that are only visible
after Packet Classification, such as Flow size and Flow duration. An
example is the selection of the largest Flows or a percentage of
Flows with the longest lifetime. Another example is to select and
remove from the Flow Cache the Flow Record with the lowest Flow
volume per current Flow life time, in case the Flow Cache is full.
An Intermediate Flow Selection Process using Property Match Filtering
within an IPFIX Mediator selects a Flow Record if the value of a
specific field in the Flow Record equals a configured value or falls
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within a configured range [RFC6183].
6.1.2. Hash-based Flow Filtering
Hash-based Flow Filtering uses a Hash Function h to map the Flow Key
c onto a Hash Range R. A Flow is selected if the hash value h(c) is
within the Hash Selection Range S, which is a subset of R. Hash-based
Flow Filtering can be used to emulate a random sampling process but
still enable the correlation between selected Flow subsets at
different Observation Points. Hash-based Flow Filtering is similar
to Hash-based Packet Selection, and in fact is identical when Hash-
based Packet Selection uses the Flow Key that defines the Flow as the
hash input. Nevertheless there may be the incentive to apply Hash-
based Flow Filtering not on the packet level in the Metering Process,
for example when the size of the selection range and therefore the
sampling probability is dependent on the number of observed Flows.
In case Hash-based Flow Filtering is used to select the same subset
of flows at different Observation Points, the Hash Domain MUST only
include parts of the Flow Record content thar are invariant on the
Flow path. Also refer to the according Trajectory Sampling
Application Example on packet level in [RFC5475] that explains the
hash-based filtering approach on packet level.
6.2. Flow Sampling
Flow Sampling operates on Flow Record sequence or arrival times. It
can use either a systematic or a random function for the Intermediate
Flow Selection Process. Flow Sampling usually aims at the selection
of a representative subset of all Flows in order to estimate
characteristics of the whole set (e.g. mean Flow size in the
network).
6.2.1. Systematic sampling
Systematic sampling is a deterministic selection function.
Systematic sampling may be a periodic selection of the N-th Flow
Record which arrives at the Intermediate Flow Selection Process.
Systematic sampling MAY be applied in the Metering Process. An
example would be to create, besides the Flow Cache of selected Flows,
an additional data structure that saves the Flow Keys values of the
Flows that are not selected. The selection of a Flow would then be
based on the first packet of a Flow. Everytime a packet belonging to
a new Flow (which is neither in the data structure of the selected or
not selected Flows) arrives at the Observation Point, a counter is
increased. In case the counter is increased to a multiple of N a new
Flow Cache entry is created, and in case the counter is not a
multiple of N the Flow Key value is added to the data structure for
not selected Flows.
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Systematic sampling can also be time-based. Time-based systematic
sampling is applied by only creating Flows that are observed between
time-based start and stop triggers. The time interval may be applied
at packet level in the Metering Process or after aggregation on Flow
level, e.g. by selecting a Flow arriving at the Exporting Process
every n seconds.
6.2.2. Random Sampling
Random Flow sampling is based on a random process which requires the
calculation of random numbers. One can differentiate between n-out-N
and probabilistic Flow sampling.
6.2.2.1. n-out-of-N Flow Sampling
In n-out-of-N Sampling, n elements are selected out of the parent
population that consists of N elements. One example would be to
generate n different random numbers in the range [1,N] and select all
Flows that have a Flow Position equal to one of the random numbers.
6.2.2.2. Probabilistic Flow Sampling
In probabilistic Sampling, the decision whether or not a Flow is
selected is made in accordance with a predefined selection
probability. For probabilistic Sampling, the Sample Size can vary
for different trials. The selection probability does not necessarily
have to be the same for each Flow. Therefore, a difference is
recognized between uniform probabilistic sampling (with the same
selection probability for all Flows) and non-uniform probabilistic
sampling (where the selection probability can vary for different
Flows). For non-uniform probabilistic Flow Sampling the sampling
probability may be adjusted according to the Flow Record content. An
example would be to increase the selection probability of large
volume Flows over small volume Flows as described in the Smart
Sampling technique [DuLT01].
6.3. Flow-state Dependent Intermediate Flow Selection Process
Flow-state Dependent Intermediate Flow Selection Process can be a
deterministic or random Intermediate Flow Selection Process based on
the Flow Record content and the Flow state which may be kept
additionally for each of the Flows. External processes may update
counters, bounds and timers for each of the Flow Records and the
Intermediate Flow Selection Process utilises this information for the
selection decision. A review of Flow-state Dependent Intermediate
Flow Selection Process techniques that aim at the selection of the
most frequent items by keeping additional Flow state information can
be found in [CoHa08]. Flow-state Dependent Intermediate Flow
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Selection Process can only be applied after packet aggregation, when
a packet has been assigned to a Flow. The Intermediate Flow
Selection Process then decides based upon the Flow state for each
Flow if it is kept in the Flow Cache or not. Two Flow-state
Dependent Intermediate Flow Selection Process Algorithms are here
described:
The frequent algorithm [KaPS03] is a technique that aims at the
selection of all flows that at least exceed a 1/k fraction of the
Observed Packet Stream. The algorithm has only a Flow Cache of size
k-1 and each Flow in the Flow Cache has an additional counter. The
counter is incremented each time a packet belonging to the Flow in
the Flow Cache is observed. In case the observed packet does not
belong to any Flow all counters are decremented and if any of the
Flow counters has a value of zero the Flow is replaced with a Flow
formed from the new packet.
Lossy counting is a selection technique that identifies all Flows
whose packet count exceeds a certain percentage of the whole observed
packet stream (e.g. 5% of all packets) with a certain estimation
error e. Lossy counting separates the observed packet stream in
windows of size N=1/e, where N is an amount of consecutive packets.
For each observed Flow an additional counter will be held in the Flow
state. The counter is incremented each time a packet belonging to
the Flow is observed and all counters are decremented at the end of
each window and all Flows with a counter of zero are removed from the
Flow Cache.
6.4. Flow-state Dependent Packet Selection
Flow-state Dependent Packet Selection is not an Intermediate Flow
Selection Process technique but a packet selection technique.
Nevertheless configuration and reporting parameters for this
technique will be described in this document. An example is the
"Sample and Hold" algorithm [EsVa01] that tries to prefer large
volume Flows in the selection. When a packet arrives it is selected
when a Flow Record for this packet already exists. In case there is
no Flow Record, the packet is selected by a certain probability that
is dependent on the packet size.
7. Configuration of Intermediate Flow Selection Process Techniques
This section describes the configuration parameters of the Flow
selection techniques presented above. It provides the basis for an
information model to be adopted in order to configure the
Intermediate Flow Selection Process within an IPFIX Device. The
information model with the Information Elements (IEs) for
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Intermediate Flow Selection Process configuration is described
together with the reporting IEs in section 8. The following table
gives an overview of the defined Intermediate Flow Selection Process
techniques, where they can be applied and what their input parameters
are. Depending on where the Flow selection techniques are applied
different input parameters can be configured.
Overview of Intermediate Flow Selection Process Techniques:
+-------------------+--------------------+--------------------------+
| Location | Selection | Selection Input |
| | Technique | |
+-------------------+--------------------+--------------------------+
| In the Metering | Flow-state | packet sampling |
| Process | Dependent Packet | probabilities, Flow |
| | Selection | Selection State, packet |
| | | properties |
+-------------------+--------------------+--------------------------+
| In the Metering | Property Match | Flow record IEs, |
| Process | Flow Filtering | Selection Interval |
+-------------------+--------------------+--------------------------+
| In the Metering | Hash-based Flow | selection range, Hash |
| Process | Filtering | Function, Flow Key, |
| | | (seed) |
+-------------------+--------------------+--------------------------+
| In the Metering | Time-based | Flow Position (derived |
| Process | Systematic Flow | from arrival time of |
| | Sampling | packets), Flow Selection |
| | | State |
+-------------------+--------------------+--------------------------+
| In the Metering | Sequence-based | Flow Position (derived |
| Process | Systematic Flow | from packet position), |
| | Sampling | Flow Selection State |
+-------------------+--------------------+--------------------------+
| In the Metering | Random Flow | random number generator |
| Process | Sampling | or list and packet |
| | | position, Flow state |
+-------------------+--------------------+--------------------------+
| In the Exporting | Property Match | Flow Record content, |
| Process/ within | Flow Filtering | filter function |
| the IPFIX | | |
| Mediator | | |
+-------------------+--------------------+--------------------------+
| In the Exporting | Hash-based Flow | selection range, Hash |
| Process/ within | Filtering | Function, hash input |
| the IPFIX | | (Flow Keys and other |
| Mediator | | Flow properties) |
+-------------------+--------------------+--------------------------+
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+-------------------+--------------------+--------------------------+
| In the Exporting | Flow-state | Flow state parameters, |
| Process/ within | Dependent | random number generator |
| the IPFIX | Intermediate Flow | or list |
| Mediator | Selection Process | |
+-------------------+--------------------+--------------------------+
| In the Exporting | Time-based | Flow arrival time, Flow |
| Process/ within | Systematic Flow | state |
| the IPFIX | Sampling | |
| Mediator | | |
+-------------------+--------------------+--------------------------+
| In the Exporting | Sequence-based | Flow Position, Flow |
| Process/ within | Systematic Flow | state |
| the IPFIX | Sampling | |
| Mediator | | |
+-------------------+--------------------+--------------------------+
| In the Exporting | Random Flow | random number generator |
| Process/ within | Sampling | or list and Flow |
| the IPFIX | | Position, Flow state |
| Mediator | | |
+-------------------+--------------------+--------------------------+
Table 1: Overview of Intermediate Flow Selection Process Techniques
7.1. Intermediate Flow Selection Process Parameters
This section defines what parameters are required to describe the
most common Intermediate Flow Selection Process techniques.
Intermediate Flow Selection Process Parameters:
For Property Match Filtering:
- Information Element as specified in [iana-ipfix-assignments]):
Specifies the Information Element which is used as the property
in the filter expression. Section 8 specifies the Information
Elements that MUST be exported by an Intermediate Flow Selection
Process using Property Match Filtering.
- Selection Value or Value Interval:
Specifies the value or interval of the filter expression.
Packets and Flow Records that have a value equal to the Selection
Value or within the Interval will be selected.
For Hash-based Flow Filtering:
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- Hash Domain:
Specifies the bits from the packet or Flow which are taken as the
hash input to the Hash Function.
- Hash Function:
Specifies the name of the Hash Function that is used to calculate
the hash value. Possible Hash Functions are BOB [RFC5475], IPSX
[RFC5475], CRC-32 [Bra75]
- Hash Selection Range:
Flows that have a hash value within the Hash Selection Range are
selected. The Hash Selection Range can be a value interval or
arbitrary hash values within the Hash Range of the Hash Function.
- Random Seed or Initializer Value:
Some Hash Functions require an initializing value. In order to
make the selection decision more secure one can choose a random
seed that configures the hash function.
For Flow-state Dependent Intermediate Flow Selection Process:
- frequency threshold:
Specifies the frequency threshold s for Flow-state Dependent Flow
Selection techniques that try to find the most frequent items
within a dataset. All Flows which exceed the defined threshold
will be selected.
- accuracy parameter:
specifies the accuracy parameter e for techniques that deal with
the frequent items problems. The accuracy parameter defines the
maximum error, i.e. no Flows that have a true frequency less than
( s - e) N are selected, where s is the frequency threshold and N
is the total number of packets.
The above list of parameters for Flow-state Dependent Flow Selection
techniques is suitable for the presented frequent item and lossy
counting algorithms. Nevertheless a variety of techniques exist with
very specific parameters which are not defined here.
For Systematic time-based Flow Sampling:
- Interval length (in usec)
Defines the length of the sampling interval during which Flows
are selected.
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- Spacing (in usec)
The spacing parameter defines the spacing in usec between the end
of one sampling interval and the start of the next succeeding
interval.
For Systematic count-based Flow Sampling:
- Interval length
Defines the number of Flows that are selected within the sampling
interval.
- Spacing
The spacing parameter defines the spacing in number of observed
Flows between the end of one sampling interval and the start of
the next succeeding interval.
For random n-out-of-N Flow Sampling:
- Population Size N
The Population Size N is the number of all Flows in the
Population from which the sample is drawn.
- Sampling Size n
The sampling size n is the number of Flows that are randomly
drawn from the population N.
For probabilistic Flow Sampling:
- Sampling probability p
The sampling probability p defines the probability by which each
of the observed Flows is selected.
7.2. Description of Flow-state Dependent Packet Selection
The configuration of Flow-state Dependent Packet Selection has not
been described in [RFC5475] therefore the parameters are defined
here:
For Flow-state Dependent Packet Selection:
- packet selection probability per possible Flow state interval
Defines multiple {Flow interval, packet selection probability}
value pairs that configure the sampling probability depending on
the current Flow state.
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- additional parameters
For the configuration of Flow-state Dependent Packet Selection
additional parameters or packet properties may be required, e.g.
the packet size ([EsVa01])
8. Information Model for Intermediate Flow Selection Process
Configuration and Reporting
This section specifies the Information Elements that MUST be exported
by an Intermediate Flow Selection Process in order to support the
interpretation of measurement results from Flow measurements. The
information is mainly used to report how many packets and Flows have
been observed in total and how many of them were selected. This
helps for instance to calculate the Attained Selection Fraction (see
also [RFC5476]), which is an important parameter to provide an
accuracy statement. The IEs can provide reporting information about
Flow Records, packets or bytes. The reported metrics are total
number of elements and the number of selected elements. From this
the number of dropped elements can be derived.
List of Intermediate Flow Selection Process Information Elements:
+-----+--------------------------+------+---------------------------+
| ID | Name | ID | Name |
+-----+--------------------------+------+---------------------------+
| 301 | selectionSequenceID | 302 | selectorID |
+-----+--------------------------+------+---------------------------+
| TBD | flowSelectorAlgorithm | 1 | octetDeltaCount |
| 1 | | | |
+-----+--------------------------+------+---------------------------+
| TBD | flowSelectedOctetDeltaCo | 2 | packetDeltaCount |
| 2 | unt | | |
+-----+--------------------------+------+---------------------------+
| TBD | flowSelectedPacketDeltaC | 3 | originalFlowsPresent |
| 3 | ount | | |
+-----+--------------------------+------+---------------------------+
| TBD | flowSelectedFlowDeltaCou | TBD5 | selectorIDTotalFlowsObser |
| 4 | nt | | ved |
+-----+--------------------------+------+---------------------------+
| TBD | selectorIDTotalFlowsSele | TBD7 | samplingFlowInterval |
| 6 | cted | | |
+-----+--------------------------+------+---------------------------+
| TBD | samplingFlowSpacing | 309 | samplingSize |
| 8 | | | |
+-----+--------------------------+------+---------------------------+
| 310 | samplingPopulation | 311 | samplingProbability |
+-----+--------------------------+------+---------------------------+
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+-----+--------------------------+------+---------------------------+
| TBD | flowSamplingTimeInterval | TBD1 | flowSamplingTimeSpacing |
| 9 | | 0 | |
+-----+--------------------------+------+---------------------------+
| 326 | digestHashValue | TBD1 | hashFlowDomain |
| | | 1 | |
+-----+--------------------------+------+---------------------------+
| 329 | hashOutputRangeMin | 330 | hashOutputRangeMax |
+-----+--------------------------+------+---------------------------+
| 331 | hashSelectedRangeMin | 332 | hashSelectedRangeMax |
+-----+--------------------------+------+---------------------------+
| 333 | hashDigestOutput | 334 | hashInitialiserValue |
+-----+--------------------------+------+---------------------------+
| 320 | absoluteError | 321 | relativeError |
+-----+--------------------------+------+---------------------------+
| 336 | upperCILimit | 337 | lowerCILimit |
+-----+--------------------------+------+---------------------------+
| 338 | confidenceLevel | | |
+-----+--------------------------+------+---------------------------+
Table 2: Intermediate Flow Selection Process Information Elements
9. IANA Considerations
9.1. Registration of Information Elements
IANA will register the following IEs in the IPFIX Information
Elements registry at http://www.iana.org/assignments/ipfix/ipfix.xml
IANA Note: please replace TBD1, TBD2, TBD3, TBD4, TBD5, TBD6, TBD7,
TBD8, TBD9, TBD10, TBD11 with the assigned values, throughout the
document
9.1.1. flowSelectorAlgorithm
Description:
This Information Element identifies the Intermediate Flow
Selection Process technique (e.g., Filtering, Sampling) that is
applied by the Intermediate Flow Selection Process. Most of these
techniques have parameters. Its configuration parameter(s) MUST
be clearly specified. Further Information Elements are needed to
fully specify packet selection with these methods and all their
parameters. Further method identifiers may be added to the list
below. It might be necessary to define new Information Elements
to specify their parameters. The flowSelectorAlgorithm registry
is maintained by IANA. New assignments for the registry will be
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administered by IANA, on a First Come First Served basis
[RFC5226], subject to Expert Review [RFC5226]. Please note that
the purpose of the flow selection techniques described in this
document is the improvement of measurement functions as defined in
the Scope (Section 1). Before adding new flow selector algorithms
it should be checked what is their intended purpose and especially
if those contradict with policies defined in [RFC2804]. The
designated expert(s) should consult with the community if a
request is received that runs counter to [RFC2804]. The registry
can be updated when specifications of the new method(s) and any
new Information Elements are provided. The group of experts must
double check the flowSelectorAlgorithm definitions and Information
Elements with already defined flowSelectorAlgorithm and
Information Elements for completeness, accuracy, and redundancy.
Those experts will initially be drawn from the Working Group
Chairs and document editors of the IPFIX and PSAMP Working Groups.
The following Intermediate Flow Selection Process Techniques
identifiers are defined here:
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+----+------------------------+--------------------------+
| ID | Technique | Parameters |
+----+------------------------+--------------------------+
| 1 | Systematic count-based | flowSamplingInterval |
| | Sampling | flowSamplingSpacing |
+----+------------------------+--------------------------+
| 2 | Systematic time-based | flowSamplingTimeInterval |
| | Sampling | flowSamplingTimeSpacing |
+----+------------------------+--------------------------+
| 3 | Random n-out-of-N | samplingSize |
| | Sampling | samplingPopulation |
+----+------------------------+--------------------------+
| 4 | Uniform probabilistic | samplingProbability |
| | Sampling | |
+----+------------------------+--------------------------+
| 5 | Property Match | Information Element |
| | Filtering | Value Range |
+----+------------------------+--------------------------+
| Hash-based Filtering | hashInitialiserValue |
+----+------------------------+ hashFlowDomain |
| 6 | using BOB | hashSelectedRangeMin |
+----+------------------------+ hashSelectedRangeMax |
| 7 | using IPSX | hashOutputRangeMin |
+----+------------------------+ hashOutputRangeMax |
| 8 | using CRC | |
+----+------------------------+--------------------------+
| 9 | Flow-state Dependent | No agreed Parameters |
| | Intermediate Flow | |
| | Selection Process | |
+----+------------------------+--------------------------+
Intermediate Flow Selection Process Techniques
Abstract Data Type: unsigned16
ElementId: TBD1
Data Type Semantics: identifier
Status: Current
9.1.2. flowSelectedOctetDeltaCount
Description:
This Information Element specifies the volume in octets of all
Flows that are selected in the Intermediate Flow Selection Process
since the previous report.
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Abstract Data Type: unsigned64
ElementId: TBD2
Units: Octets
Status: Current
9.1.3. flowSelectedPacketDeltaCount
Description:
This Information Element specifies the volume in packets of all
Flows that were selected in the Intermediate Flow Selection
Process since the previous report.
Abstract Data Type: unsigned64
ElementId: TBD3
Units: Packets
Status: Current
9.1.4. flowSelectedFlowDeltaCount
Description:
This Information Element specifies the number of Flows that were
selected in the Intermediate Flow Selection Process since the last
report.
Abstract Data Type: unsigned64
ElementId: TBD4
Units: Flows
Status: Current
9.1.5. selectorIDTotalFlowsObserved
Description:
This Information Element specifies the total number of Flows
observed by a Selector, for a specific value of SelectorId. This
Information Element should be used in an Options Template scoped
to the observation to which it refers. See Section 3.4.2.1 of the
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IPFIX protocol document [I-D.ietf-ipfix-protocol-rfc5101bis].
Abstract Data Type: unsigned64
ElementId: TBD5
Units: Flows
Status: Current
9.1.6. selectorIDTotalFlowsSelected
Description:
This Information Element specifies the total number of Flows
selected by a Selector, for a specific value of SelectorId. This
Information Element should be used in an Options Template scoped
to the observation to which it refers. See Section 3.4.2.1 of the
IPFIX protocol document [I-D.ietf-ipfix-protocol-rfc5101bis].
Abstract Data Type: unsigned64
ElementId: TBD6
Units: Flows
Status: Current
9.1.7. samplingFlowInterval
Description:
This Information Element specifies the number of Flows that are
consecutively sampled. A value of 100 means that 100 consecutive
Flows are sampled. For example, this Information Element may be
used to describe the configuration of a systematic count-based
Sampling Selector.
Abstract Data Type: unsigned64
ElementId: TBD7
Units: Flows
Status: Current
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9.1.8. samplingFlowSpacing
Description:
This Information Element specifies the number of Flows between two
"samplingFlowInterval"s. A value of 100 means that the next
interval starts 100 Flows (which are not sampled) after the
current "samplingFlowInterval" is over. For example, this
Information Element may be used to describe the configuration of a
systematic count-based Sampling Selector.
Abstract Data Type: unsigned64
ElementId: TBD8
Units: Flows
Status: Current
9.1.9. flowSamplingTimeInterval
Description:
This Information Element specifies the time interval in
microseconds during which all arriving Flows are sampled. For
example, this Information Element may be used to describe the
configuration of a systematic time-based Sampling Selector.
Abstract Data Type: unsigned64
ElementId: TBD9
Units: microseconds
Status: Current
9.1.10. flowSamplingTimeSpacing
Description:
This Information Element specifies the time interval in
microseconds between two "flowSamplingTimeInterval"s. A value of
100 means that the next interval starts 100 microseconds (during
which no Flows are sampled) after the current
"flowsamplingTimeInterval" is over. For example, this Information
Element may used to describe the configuration of a systematic
time-based Sampling Selector.
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Abstract Data Type: unsigned64
ElementId: TBD10
Units: microseconds
Status: Current
9.1.11. hashFlowDomain
Description:
This Information Element specifies the Information Elements that
are used by the Hash-based Flow Selector as the Hash Domain.
Abstract Data Type: unsigned16
ElementId: TBD11
Data Type Semantics: identifier
Status: Current
9.2. Registration of Object Identifier
IANA will register the following OID in the IPFIX-SELECTOR-MIB
Functions sub-registry at http://www.iana.org/assignments/smi-numbers
according to the procedures set forth in [RFC6615]
+---------+-----------------------+---------------------+-----------+
| Decimal | Name | Description | Reference |
+---------+-----------------------+---------------------+-----------+
| | flowSelectorAlgorithm | This Object | TBDx |
| | | Identifier | [RFCyyyy] |
| | | identifies the | |
| | | Intermediate Flow | |
| | | Selection Process | |
| | | technique (e.g., | |
| | | Filtering, | |
| | | Sampling) that is | |
| | | applied by the | |
| | | Intermediate Flow | |
| | | Selection Process | |
+---------+-----------------------+---------------------+-----------+
Table 4: Object Identifiers to be registered
IANA Note: please replace TBDx with the assigned value, throughout
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the document.
Editor's Note (to be removed prior to publication): the RFC editor is
asked to replace "yyyy" in this document by the number of the RFC
when the assignment has been made.
10. Security and Privacy Considerations
Flow data exported by Exporting Processes, and collected by
Collecting Processes, can be sensitive for privacy reasons and need
to be protected. Privacy considerations for collected data are
provided in [I-D.ietf-ipfix-protocol-rfc5101bis].
Some of the described Intermediate Flow Selection Process techniques
(e.g., flow sampling, hash-based flow filtering) aim at the selection
of a representative subset of flows in order to estimate parameters
of the population. An adversary may have incentives to influence the
selection of flows, for example to circumvent accounting or to avoid
the detection of packets that are part of an attack.
Security considerations concerning the choice of a Hash Function for
Hash-based Packet Selection have been discussed in Section 6.2.3 of
[RFC5475] and are also appropriate for Hash-based Flow Selection.
[RFC5475] discusses the possibility to craft Packet Streams which are
disproportionately selected or can be used to discover Hash Function
parameters. It also describes vulnerabilities of different Hash
Functions to these attacks, and practices to minimize these
vulnerabilities.
For other sampling approaches an adversary can gain knowledge about
the start and stop triggers in time-based systematic Sampling, e.g.,
by sending test packets. This knowledge might allow adversariess to
modify their send schedule in a way that their packets are
disproportionately selected or not selected. For random Sampling, an
input to the encryption process, like the Initialization Vector of
the CBC (Cipher Block Chaining) mode, should be used to prevent that
an advisory can predict the selection decision [Dw01].
Further security threats can occur when Intermediate Flow Selection
Process parameters are configured or communicated to other entities.
The protocol(s) for the configuration and reporting of Intermediate
Flow Selection Process parameters are out of scope of this document.
Nevertheless, a set of initial requirements for future configuration
and reporting protocols are stated below:
1. Protection against disclosure of configuration information:
Intermediate Flow Selection Process configuration information
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describes the Intermediate Flow Selection Process and its
parameters. This information can be useful to attackers.
Attackers may craft packets that never fit the selection criteria
in order to prevent Flows to be seen by the Intermediate Flow
Selection Process. They can also craft a lot of packets that fit
the selection criteria and overload or bias subsequent processes.
Therefore any transmission of configuration data (e.g., to
configure a process or to report its actual status) should be
protected by encryption.
2. Protection against modification of configuration information: if
wrong configuration information is sent to the Intermediate Flow
Selection Process, it can lead to a malfunction of the
Intermediate Flow Selection Process. Also if wrong configuration
information is reported from the Intermediate Flow Selection
Process to other processes it can lead to wrong estimations at
subsequent processes. Therefore any protocol that transmits
configuration information should prevent that an attacker can
modify configuration information. Data integrity can be achieved
by authenticating the data.
3. Protection against malicious nodes sending configuration
information: the remote configuration of Intermediate Flow
Selection Process techniques should be protected against access
by unauthorized nodes. This can be achieved by access control
lists at the device that hosts the Intermediate Flow Selection
Process (e.g. IPFIX Exporter, IPFIX Mediator or IPFIX Collector)
and by source authentication. The reporting of configuration
data from an Intermediate Flow Selection Process has to be
protected in the same way. That means that also protocols that
report configuration data from the Intermediate Flow Selection
Process to other processes need to protect against unauthorized
nodes reporting configuration information.
The security threats that originate from communicating configuration
information to and from Intermediate Flow Selection Processes cannot
be assessed solely with the information given in this document. A
further more detailed assessment of security threats is necessary
when a specific protocol for the configuration or reporting
configuration data is proposed.
11. Acknowledgments
We would like to thank the IPFIX group, especially Brian Trammell,
Paul Aitken and Benoit Claise for fruitful discussions and for
proofreading the document.
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12. References
12.1. Normative References
[I-D.ietf-ipfix-protocol-rfc5101bis]
Claise, B. and B. Trammell, "Specification of the IP Flow
Information eXport (IPFIX) Protocol for the Exchange of
Flow Information", draft-ietf-ipfix-protocol-rfc5101bis-07
(work in progress), May 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J.
Meyer, "Information Model for IP Flow Information Export",
RFC 5102, January 2008.
[RFC5475] Zseby, T., Molina, M., Duffield, N., Niccolini, S., and F.
Raspall, "Sampling and Filtering Techniques for IP Packet
Selection", RFC 5475, March 2009.
[RFC5476] Claise, B., Johnson, A., and J. Quittek, "Packet Sampling
(PSAMP) Protocol Specifications", RFC 5476, March 2009.
[RFC6615] Dietz, T., Kobayashi, A., Claise, B., and G. Muenz,
"Definitions of Managed Objects for IP Flow Information
Export", RFC 6615, June 2012.
12.2. Informative References
[Bra75] Brayer, K., "Evaluation of 32 Degree Polynomials in Error
Detection on the SATIN IV Autovon Error Patterns",
National Technical Information Service p.74, August 1975.
[CoHa08] Cormode, G. and M. Hadjieleftheriou, "Finding frequent
items in data streams", Journal, Proceedings of the Very
Large DataBase Endowment VLDB Endowment, Volume 1 Issue 2,
August 2008, August 2008.
[DuLT01] Duffield, N., Lund, C., and M. Thorup, "Charging from
Sampled Network Usage", ACM Internet Measurement Workshop
IMW 2001, San Francisco, USA, November 2001.
[Dw01] Dworkin, M., "Recommendation for Block Cipher Modes of
Operation - Methods and Techniques", NIST Special
Publication NIST Special Publication 800-38A 2001 Edition,
December 2001.
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[EsVa01] Estan, C. and G,. Varghese, "New Directions in Traffic
Measurement and Accounting: Focusing on the Elephants,
Ignoring the Mice", ACM SIGCOMM Internet Measurement
Workshop 2001, San Francisco (CA), November 2001.
[KaPS03] Karp, R., Papadimitriou, C., and S. S. Shenker, "A simple
algorithm for finding frequent elements in sets and
bags.", ACM Transactions on Database Systems, Volume 28,
51-55, 2003, March 2003.
[MSZC10] Mai, J., Sridharan, A., Zang, H., and C. Chuah, "Fast
Filtered Sampling", Computer Networks Volume 54, Issue 11,
Pages 1885-1898, ISSN 1389-1286, January 2010.
[MaMo02] Manku, G. and R. Motwani, "Approximate Frequency Counts
over Data Streams", Proceedings of the International
Conference on Very large DataBases (VLDB) pages 346--357,
2002, Hong Kong, China, 2002.
[RFC2804] IAB and IESG, "IETF Policy on Wiretapping", RFC 2804,
May 2000.
[RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander,
"Requirements for IP Flow Information Export (IPFIX)",
RFC 3917, October 2004.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J. Quittek,
"Architecture for IP Flow Information Export", RFC 5470,
March 2009.
[RFC6183] Kobayashi, A., Claise, B., Muenz, G., and K. Ishibashi,
"IP Flow Information Export (IPFIX) Mediation: Framework",
RFC 6183, April 2011.
[iana-ipfix-assignments]
"IP Flow Information Export Information Elements", 2007,
<http://www.iana.org/assignments/ipfix/ipfix.xml>.
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Authors' Addresses
Salvatore D'Antonio
University of Napoli "Parthenope"
Centro Direzionale di Napoli Is. C4
Naples 80143
Italy
Phone: +39 081 5476766
Email: salvatore.dantonio@uniparthenope.it
Tanja Zseby
CAIDA/FhG FOKUS
San Diego Supercomputer Center (SDSC)
University of California, San Diego (UCSD)
9500 Gilman Drive
La Jolla CA 92093-0505
USA
Email: tanja@caida.org
Christian Henke
Tektronix Communication Berlin
Wohlrabedamm 32
Berlin 13629
Germany
Phone: +49 17 2323 8717
Email: christian.henke@tektronix.com
Lorenzo Peluso
University of Napoli
Via Claudio 21
Napoli 80125
Italy
Phone: +39 081 7683821
Email: lorenzo.peluso@unina.it
D'Antonio, et al. Expires December 1, 2013 [Page 33]
