One document matched: draft-ietf-behave-ipfix-nat-logging-02.xml
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<rfc category="std" docName="draft-ietf-behave-ipfix-nat-logging-02"
ipr="trust200902">
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<!-- ***** FRONT MATTER ***** -->
<front>
<!-- The abbreviated title is used in the page header - it is only necessary if the
full title is longer than 39 characters -->
<title abbrev="IPFIX IEs for NAT logging">IPFIX Information Elements for logging NAT Events</title>
<!-- add 'role="editor"' below for the editors if appropriate -->
<!-- Another author who claims to be an editor -->
<author fullname="Senthil Sivakumar" initials="S." surname="Sivakumar">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>7100-8 Kit Creek Road</street>
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<city>Research Triangle Park</city>
<region>North Carolina</region>
<code>27709</code>
<country>USA</country>
</postal>
<phone>+1 919 392 5158</phone>
<email>ssenthil@cisco.com</email>
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</address>
</author>
<author fullname="Renaldo Penno" initials="R." surname="Penno">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>170 W Tasman Drive</street>
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<city>San Jose</city>
<region>California</region>
<code>95035</code>
<country>USA</country>
</postal>
<phone></phone>
<email>repenno@cisco.com</email>
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</address>
</author>
<date month="November" year="2013" />
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<area>General</area>
<workgroup>Behave</workgroup>
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<abstract>
<t>NAT devices are required to log events like
creation and deletion of translations and information about the
resources it is managing.
The logs are required in many cases to
identify an attacker or a host that was used to launch malicious attacks
and/or for various other purposes of accounting. Since there is no
standard way of logging this information, different NAT devices behave
differently and hence it is difficult to expect a consistent behavior.
The lack of a consistent way makes it difficult to write the collector
applications that would receive this data and process it to present
useful information. This document describes the information that is
required to be logged by the NAT devices.</t>
</abstract>
</front>
<middle>
<section title="Terminology">
<t>The usage of the term "NAT device" in this document refer to any
NAT44 and NAT64 devices. The usage of the term "collector"
refers to any device that receives the binary data from a NAT device and
converts that into meaningful information. This document uses the term
"Session" as it is defined in <xref target="RFC2663"> </xref> and the
term BIB as it is defined in <xref target="RFC6146"></xref>. The usage
of the term Information Element (IE) is defined in
[RFC5101bis].</t>
</section>
<section title="Introduction">
<t>The IPFIX Protocol [RFC5101bis] defines a generic push mechanism for exporting information
and events. The IPFIX Information Model [IPFIX-IANA] defines a set of standard Information Elements
(IEs) which can be carried by the IPFIX protocol. This document details the IPFIX Information
Elements(IEs) that are required for logging by a NAT device. The document will specify the
format of the IE's that are required to be logged by the NAT device and all the optional fields. The
fields specified in this document are gleaned from <xref target="RFC4787"></xref> and <xref
target="RFC5382"></xref>.</t>
<t> Test [3GPP] </t>
<t>
This document and [I-D.behave-syslog-nat-logging] are provided in order to standardize
the events and parameters to be recorded, using IPFIX [RFC5101bis]
and SYSLOG [RFC5424]respectively. </t>
<section title="Requirements Language">
<t>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 <xref
target="RFC2119"></xref>.</t>
</section>
</section>
<section title="Scope">
<t>This document provides the information model to be used for logging
the NAT devices including Carrier Grade NAT (CGN) events. This document focuses exclusively on
the specification of IPFIX IE's.
This document does not provide guidance on the transport protocol like TCP, UDP or
SCTP that is to be used to log NAT events.
The log events SHOULD NOT be lost but the choice of the actual transport
protocol is beyond the scope of this document.</t>
<t>The existing IANA IPFIX IEs registry [IPFIX-IANA]
already has assignments for many NAT logging events. For convenience,
this document uses those same IEs. However, as stated
earlier, this document is not defining IPFIX or NetFlow v9 as the
framework for logging. Rather, the information contained in these
elements is within the scope of this document.</t>
<t>This document assumes that the NAT device will use the existing
IPFIX framework to send the log events to
the collector. This would mean that the NAT device will specify the template
that it is going to use for each of the events.
The templates can be of varying length and there could be multiple
templates that a NAT device could use to log the events. </t>
<t>The implementation details of the collector application is beyond the
scope of this document.</t>
<t>The optimization of logging the NAT events are left to the
implementation and are beyond the scope of this document.</t>
</section>
<section title="Applicability">
<t>NAT logging based on IPFIX uses binary encoding and hence is very efficient.
IPFIX based logging is recommended for environments where a high volume of logging is
required, for example, where per-flow logging is needed.
However, IPFIX based logging requires a collector that processes the binary
data and requires a network management application that converts this binary
data to a human readable format.</t>
</section>
<section title="Event based logging">
<t>An event in a NAT device can be viewed as a happening as it relates
to the management of NAT resources. The creation and deletion of NAT
sessions and bindings are examples of events as it results in the
resources (addresses and ports) being allocated or freed. The events can
happen either through the processing of data packets flowing through the
NAT device or through an external entity installing policies on the NAT
router or as a result of an asynchronous event like a timer.
The list of events are provided in Section 4.1. Each of these
events SHOULD be logged, unless they are administratively prohibited. A
NAT device MAY log these events to multiple collectors if redundancy is
required. The network administrator will specify the collectors to which
the log records are to be sent.</t>
<t> A collector may receive NAT events from multiple CGN devices and should be able
to distinguish between the devices. Each CGN device should have a unique source ID to
identify themselves. The source ID is part of the IPFIX template and data exchange.</t>
<t> Prior to logging any events, the NAT device MUST send the template of
the record to the collector to advertise the format of the data record
that it is using to send the events. The templates can be exchanged as
frequently as required given the reliability of the connection. There SHOULD
be a configurable timer for controlling the template refresh. NAT
device SHOULD combine as many events as possible in a single packet to
effectively utilize the network bandwidth.</t>
<section title="Logging of destination information">
<t> Logging of destination information in a NAT event has been discussed in
<xref target="RFC6302"></xref> and
<xref target="RFC6888"></xref>.
Logging of destination information increases the size of each record and
increases the need for storage considerably. It increases the number of log events
generated because when the same user connects to a different destination,
it results in a log record per destination address. Logging of destination
information also results in the loss of privacy and hence should be done with caution.
However, this draft provides the necessary fields to log the destination information
in cases where they are required to be logged.
</t>
</section>
<section title="Information Elements">
<t>The templates could contain a subset of the Information
Elements(IEs) shown in Table 1 depending upon the event being logged.
For example a NAT44 session creation template record will contain,</t>
<t>{sourceIPv4Adress, postNATSourceIPv4Address,
destinationIpv4Address, postNATDestinationIPv4Address,
sourceTransportPort, postNAPTSourceTransportPort,
destinationTransportPort, postNAPTDestTransportPort,
natOriginatingAddressRealm, natEvent, timeStamp}</t>
<t>An example of the actual event data record is shown below - in a
readable form</t>
<t>{192.168.16.1, 201.1.1.100, 207.85.231.104, 207.85.231.104, 14800,
1024, 80, 80, 0, 1, 09:20:10:789}</t>
<t>A single NAT device could be exporting multiple templates and the
collector should support receiving multiple templates from the same
source.
<vspace blankLines='50' />
</t>
<t> The following is the table of all the IE's that a CGN device would need
to export the events. The formats of the IE's and the IPFIX IDs are listed
below. </t>
<texttable anchor="Template_table" title="Template format Table">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="right">IANA IPFIX ID</ttcol>
<ttcol align="center">Description</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>323</c>
<c>System Time when the event occured.</c>
<c>vlanID</c>
<c>16</c>
<c>58</c>
<c>VLAN ID in case of overlapping networks</c>
<c>ingressVRFID</c>
<c>32</c>
<c>234</c>
<c>VRF ID in case of overlapping networks</c>
<c>sourceIPv4Address</c>
<c>32</c>
<c>8</c>
<c>Source IPv4 Address</c>
<c>postNATSourceIPv4Address</c>
<c>32</c>
<c>225</c>
<c>Translated Source IPv4 Address</c>
<c>protocolIdentifier</c>
<c>8</c>
<c>4</c>
<c>Transport protocol</c>
<c>sourceTransportPort</c>
<c>16</c>
<c>7</c>
<c>Source Port</c>
<c>postNAPTsourceTransportPort</c>
<c>16</c>
<c>227</c>
<c>Translated Source port</c>
<c>destinationIPv4Address</c>
<c>32</c>
<c>12</c>
<c>Destination IPv4 Address</c>
<c>postNATDestinationIPv4Address</c>
<c>32</c>
<c>226</c>
<c>Translated IPv4 destination address</c>
<c>destinationTransportPort</c>
<c>16</c>
<c>11</c>
<c>Destination port</c>
<c>postNAPTdestinationTransportPort</c>
<c>16</c>
<c>228</c>
<c>Translated Destination port</c>
<c>sourceIPv6Address</c>
<c>27</c>
<c>128</c>
<c>Source IPv6 address</c>
<c>destinationIPv6Address</c>
<c>128</c>
<c>28</c>
<c>Destination IPv6 address</c>
<c>postNATSourceIPv6Address</c>
<c>128</c>
<c>281</c>
<c>Translated source IPv6 addresss</c>
<c>postNATDestinationIPv6Address</c>
<c>128</c>
<c>282</c>
<c>Translated Destination IPv6 address</c>
<c>natOriginatingAddressRealm</c>
<c>8</c>
<c>229</c>
<c>Address Realm</c>
<c>natEvent</c>
<c>8</c>
<c>230</c>
<c>Type of Event</c>
<c>portRangeStart</c>
<c>16</c>
<c>361</c>
<c>Allocated port block start</c>
<c>portRangeEnd</c>
<c>16</c>
<c>362</c>
<c>Allocated Port block end</c>
<c>portRangeStepSize</c>
<c>16</c>
<c>363</c>
<c>Step size of next port</c>
<c>portRangeNumPorts</c>
<c>16</c>
<c>364</c>
<c>Number of ports</c>
</texttable>
</section>
<!-- End of section IEs above -->
<section title="Definition of NAT Events">
<t>The following are the list of NAT events and the proposed event
values. The list can be expanded in the future as necessary. The data
record will have the corresponding natEvent value to identify the
event that is being logged.</t>
<texttable anchor="event_id_table" title="NAT Event ID table">
<ttcol align="center">Event Name</ttcol>
<ttcol align="right">Values</ttcol>
<c>NAT44 Session create</c>
<c>1</c>
<c>NAT44 Session delete</c>
<c>2</c>
<c>NAT Addresses exhausted</c>
<c>3</c>
<c>NAT64 Session create</c>
<c>4</c>
<c>NAT64 Session delete</c>
<c>5</c>
<c>NAT44 BIB create</c>
<c>6</c>
<c>NAT44 BIB delete</c>
<c>7</c>
<c>NAT64 BIB create</c>
<c>8</c>
<c>NAT64 BIB delete</c>
<c>9</c>
<c>NAT ports exhausted</c>
<c>10</c>
<c>Quota exceeded</c>
<c>11</c>
<c>Address binding create</c>
<c>12</c>
<c>Address binding delete</c>
<c>13</c>
<c>Port block allocation</c>
<c>14</c>
<c>Port block de-allocation</c>
<c>15</c>
</texttable>
</section>
<section title="Quota exceeded - natLimitEvent types">
<t> The following table shows the sub event types for the Quota exceeded event </t>
<texttable anchor="limid_id_table" title="Sub Event ID table">
<ttcol align="center">Quota Exceeded Event Name</ttcol>
<ttcol align="right">Values</ttcol>
<c>Max Session entries </c>
<c>1</c>
<c>Max BIB entries </c>
<c>2</c>
<c>Max entries per user</c>
<c>3</c>
</texttable>
</section>
<section title="Templates for NAT Events">
<t>The following is the template of events that will have to logged.
The events below are identified at the time of this writing but
the events are expandable. Depending on the implementation and
configuration various IE's specified can be included or ignored.</t>
<section title="NAT44 create and delete session events">
<t>These events will be generated when a NAT44 session is created or
deleted. The template will be the same, the natEvent will indicate
whether it is a create or a delete event. The following is a
template of the event.</t>
<texttable anchor="event_template_table"
title="NAT44 Session delete/create template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>vlanID/ingressVRFID</c>
<c>32</c>
<c>No</c>
<c>sourceIPv4Address</c>
<c>32</c>
<c>Yes</c>
<c>postNATSourceIPv4Address</c>
<c>32</c>
<c>Yes</c>
<c>protocolIdentifier</c>
<c>8</c>
<c>Yes</c>
<c>sourceTransportPort</c>
<c>16</c>
<c>Yes</c>
<c>postNAPTsourceTransportPort</c>
<c>16</c>
<c>Yes</c>
<c>destinationIPv4Address</c>
<c>32</c>
<c>No</c>
<c>postNATDestinationIPv4Address</c>
<c>32</c>
<c>No</c>
<c>destinationTransportPort</c>
<c>16</c>
<c>No</c>
<c>postNAPTdestinationTransportPort</c>
<c>16</c>
<c>No</c>
<c>natOriginatingAddressRealm</c>
<c>8</c>
<c>No</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
</texttable>
</section>
<!-- End of section nat44 create/delete above -->
<section title="NAT64 create and delete session events">
<t>These events will be generated when a NAT64 session is created or deleted. The
following is a template of the event.</t>
<texttable anchor="nat64_session_event_template_table"
title="NAT64 session create/delete event template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>vlanID/ingressVRFID</c>
<c>32</c>
<c>No</c>
<c>sourceIPv6Address</c>
<c>128</c>
<c>Yes</c>
<c>postNATSourceIPv4Address</c>
<c>32</c>
<c>Yes</c>
<c>protocolIdentifier</c>
<c>8</c>
<c>Yes</c>
<c>sourceTransportPort</c>
<c>16</c>
<c>Yes</c>
<c>postNAPTsourceTransportPort</c>
<c>16</c>
<c>Yes</c>
<c>destinationIPv6Address</c>
<c>128</c>
<c>No</c>
<c>postNATDestinationIPv4Address</c>
<c>32</c>
<c>No</c>
<c>destinationTransportPort</c>
<c>16</c>
<c>No</c>
<c>postNAPTdestinationTransportPort</c>
<c>16</c>
<c>No</c>
<c>natOriginatingAddressRealm</c>
<c>8</c>
<c>No</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
</texttable>
</section>
<!-- End of section nat64 delete/create above -->
<section title="NAT44 BIB create and delete events">
<t>These events will be generated when a NAT44 Bind entry is created or deleted.
The following is a template of the event.</t>
<texttable anchor="nat44_bib_event_template_table"
title="NAT44 BIB create/delete event template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>vlanID/ingressVRFID</c>
<c>32</c>
<c>No</c>
<c>sourceIPv4Address</c>
<c>32</c>
<c>Yes</c>
<c>postNATSourceIPv4Address</c>
<c>32</c>
<c>Yes</c>
<c>protocolIdentifier</c>
<c>8</c>
<c>No</c>
<c>sourceTransportPort</c>
<c>16</c>
<c>No</c>
<c>postNAPTsourceTransportPort</c>
<c>16</c>
<c>No</c>
<c>natOriginatingAddressRealm</c>
<c>8</c>
<c>No</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
</texttable>
</section>
<!-- End of section nat44 BIB above -->
<section title="NAT64 BIB create and delete events">
<t>These events will be generated when a NAT64 Bind entry is created or deleted.
The following is a template of the event.</t>
<texttable anchor="nat64_bib_event_template_table"
title="NAT64 BIB create/delete event template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>vlanID/ingressVRFID</c>
<c>32</c>
<c>No</c>
<c>sourceIPv6Address</c>
<c>128</c>
<c>Yes</c>
<c>postNATSourceIPv4Address</c>
<c>32</c>
<c>Yes</c>
<c>protocolIdentifier</c>
<c>8</c>
<c>No</c>
<c>sourceTransportPort</c>
<c>16</c>
<c>No</c>
<c>postNAPTsourceTransportPort</c>
<c>16</c>
<c>No</c>
<c>natOriginatingAddressRealm</c>
<c>8</c>
<c>No</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
</texttable>
</section>
<section title="Addresses Exhausted event">
<t>This event will be generated when a NAT device runs out of global
IPv4 addresses in a given pool of addresses. Typically, this event would mean that the NAT device
wont be able to create any new translations until some
addresses/ports are freed. This event SHOULD be rate limited as many packets hitting the
device at the same time will trigger a burst of addresses exhausted events. </t>
<t> The following is a template of the event.</t>
<texttable anchor="nat_adress_exhaust_template_table"
title="NAT Address Exhausted event template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
<c>natPoolName</c>
<c>String</c>
<c>Yes</c>
</texttable>
</section>
<!-- End of section nat address exhaust event above -->
<section title="Ports Exhausted event">
<t>This event will be generated when a NAT device runs out of ports
for a global IPv4 address. Port exhaustion shall be reported per
protocol (UDP, TCP etc). This event SHOULD be rate limited as many packets hitting the
device at the same time will trigger a burst of port exhausted events. </t>
<t>The following is a template of the event. </t>
<texttable anchor="nat_ports_exhaust_template_table"
title="NAT Ports Exhausted event template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
<c>postNATSourceIPv4Address</c>
<c>32</c>
<c>Yes</c>
<c>protocolIdentifier</c>
<c>8</c>
<c>Yes</c>
</texttable>
</section>
<!-- End of section nat ports exhaust event above -->
<section title="Quota exceeded">
<t>This event will be generated when a NAT device cannot allocate
resources as a result of an administratively defined policy. The
examples of Quota exceeded are to allow only certain number of NAT
sessions per device, certain number of NAT sessions per user etc.
The following is a template of the event.</t>
<texttable anchor="nat_quota_exceeded_template_table"
title="NAT Quota Exceeded event template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
<c>natLimitEvent</c>
<c>32</c>
<c>Yes</c>
<c>sourceIPv4 address</c>
<c>32</c>
<c>Yes for NAT44</c>
<c>sourceIPv6 address</c>
<c>128</c>
<c>Yes for NAT64</c>
</texttable>
</section>
<section title="Address binding create and delete events">
<t>These events will be generated when a NAT device binds a local address with a global address and when the global address is freed.
This binding event happens when the first packet of the first flow from a host in the private
realm. </t>
<texttable anchor="address_binding_template_table"
title="NAT Address Binding template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>natEvent</c>
<c>8</c>
<c>Yes</c>
<c>sourceIPv4 address</c>
<c>32</c>
<c>Yes for NAT44</c>
<c>sourceIPv6 address</c>
<c>128</c>
<c>Yes for NAT64</c>
<c>Translated Source IPv4 Address</c>
<c>32</c>
<c>Yes</c>
</texttable>
</section>
<section title="Port block allocation and de-allocation">
<t>This event will be generated when a NAT device allocates/de-allocates ports
in a bulk fashion, as opposed to allocating a port on a per flow basis. </t>
<t> portRangeStart represents the starting value of the range. </t>
<t> portRangeEnd represents the ending value of the range. </t>
<t> portRangeNumPorts represents the number of ports that are allocated to the user. </t>
<t> portRangeStepSize represents the step size in case of non-contiguous port allocation. </t>
<t> NAT devices would do this in order to reduce logs
and potentially to limit the number of connections a subscriber is allowed to use. In the
following Port Block allocation template, the portRangeStart must be specified.
Along with portRangeStart,
atleast one of portRangeEnd, portRangeStepSize or portRangeNumPorts MUST be specified.
If portRangeEnd is specified, it MUST NOT be lesser than portRangeStart.
The value of portRangeStepSize MUST be between 1 and 32K. </t>
<t> It is up to the implementation to choose to consolidate log records in case two
consecutive port ranges for the same user are allocated or freed.
</t>
<texttable anchor="nat_bulk_port_allocation_template_table"
title="NAT Port Block Allocation event template">
<ttcol align="center">Field Name</ttcol>
<ttcol align="right">Size (bits)</ttcol>
<ttcol align="center">Mandatory</ttcol>
<c>timeStamp</c>
<c>64</c>
<c>Yes</c>
<c>sourceIPv4 address</c>
<c>32</c>
<c>Yes for NAT44</c>
<c>sourceIPv6 address</c>
<c>128</c>
<c>Yes for NAT64</c>
<c>Translated Source IPv4 Address</c>
<c>32</c>
<c>Yes</c>
<c>portRangeStart</c>
<c>16</c>
<c>Yes</c>
<c>portRangeEnd</c>
<c>16</c>
<c>No</c>
<c>portRangeStepSize</c>
<c>16</c>
<c>No</c>
<c>portRangeNumPorts</c>
<c>16</c>
<c>No</c>
</texttable>
</section>
<!-- End of section nat ports exhaust event above -->
</section>
<!-- End of section templates above -->
</section>
<!-- End of section Event based logging above -->
<section anchor="Encoding" title="Encoding">
<section title="IPFIX">
<t>
This document uses IPFIX as the encoding mechanism to describe the logging of NAT events. However, the information that
should be logged SHOULD be the same irrespective of what kind of encoding scheme is used. IPFIX is chosen because is it
an IETF standard that meets all the needs for a reliable logging mechanism. IPFIX provides the flexibility to the
logging device to define the data sets that it is logging. The IEs specified for logging MUST be
the same irrespective of the encoding mechanism used.
</t>
</section>
</section>
<section anchor="Acknowledgements" title="Acknowledgements">
<t>Thanks to Dan Wing, Selvi Shanmugam, Mohamed Boucadir, Jacni Qin
Ramji Vaithianathan, Simon Perreault, Jean-Francois Tremblay, Paul Aitken and Julia Renouard for their review
and comments.</t>
</section>
<!-- Possibly a 'Contributors' section ... -->
<section anchor="IANA" title="IANA Considerations">
<t> There are no IANA considerations for this document. </t>
</section>
<section anchor="Management" title="Management Considerations">
<t>This section considers requirements for management of the log system
to support logging of the events described above. It first covers
requirements applicable to log management in general. Any additional
standardization required to fullfil these requirements is out of scope
of the present document. Some management considerations is covered in
[I-D.behave-syslog-nat-logging]. This document covers the additional
considerations. </t>
<section title="Ability to collect events from multiple NAT devices">
<t>
An IPFIX collector should be able to collect events from multiple NAT devices and be able to
decipher events based on the sourceID in the IPFIX header.
</t>
</section>
<section title="Ability to suppress events">
<t>
The exhaustion events can be overwhelming during traffic bursts and hence should be handled
by the NAT devices to rate limit them before sending them to the collectors. For eg. when the
port exhaustion happens during bursty conditions, instead of sending a port exhaustion event
for every packet, the exhaustion events should be rate limited by the NAT device.
</t>
</section>
</section>
<section anchor="Security" title="Security Considerations">
<t>None.</t>
</section>
</middle>
<!-- *****BACK MATTER ***** -->
<back>
<!-- References split into informative and normative -->
<!-- There are 2 ways to insert reference entries from the citation libraries:
1. define an ENTITY at the top, and use "ampersand character"RFC2629; here (as shown)
2. simply use a PI "less than character"?rfc include="reference.RFC.2119.xml"?> here
(for I-Ds: include="reference.I-D.narten-iana-considerations-rfc2434bis.xml")
Both are cited textually in the same manner: by using xref elements.
If you use the PI option, xml2rfc will, by default, try to find included files in the same
directory as the including file. You can also define the XML_LIBRARY environment variable
with a value containing a set of directories to search. These can be either in the local
filing system or remote ones accessed by http (http://domain/dir/... ).-->
<references title="Normative References">
<?rfc include="reference.RFC.2119.xml"?>
<?rfc include="reference.RFC.2663.xml"?>
<?rfc include="reference.RFC.4787.xml"?>
<?rfc include="reference.RFC.5382.xml"?>
<?rfc include="reference.RFC.6146.xml"?>
<?rfc include="reference.RFC.6302.xml"?>
<?rfc include="reference.RFC.6888.xml"?>
</references>
<references title="Informative References">
<?rfc include="reference.RFC.5470.xml"?>
<?rfc include="reference.I-D.ietf-behave-syslog-nat-logging.xml"?>
<reference anchor="RFC5101bis">
<front>
<title>Specification of the IP Flow Information eXport (IPFIX) Protocol for the Exchange of Flow Information</title>
<author initials="B." surname="Claise" fullname="B. Claise">
<organization>Cisco Systems</organization>
</author>
<author initials="B." surname="Trammel" fullname="B. Trammel">
<organization>ETH Zurich</organization>
</author>
<date month="July" year="2013"/>
</front>
</reference>
<reference anchor="RFC5102bis">
<front>
<title>Information Model for IP Flow Information eXport (IPFIX)</title>
<author initials="B." surname="Claise" fullname="B. Claise">
<organization>Cisco Systems</organization>
</author>
<author initials="B." surname="Trammel" fullname="B. Trammel">
<organization>ETH Zurich</organization>
</author>
<date month="February" year="2013"/>
</front>
</reference>
<reference anchor="IPFIX-IANA"
target="http://www.iana.org/assignments/ipfix">
<front>
<title>IPFIX Information Elements registry</title>
<author>
<organization>IANA</organization>
</author>
<date/>
</front>
</reference>
<!--
Here we use entities that we defined at the beginningI. -->
</references>
<!-- Change Log
v00 2006-03-15 EBD Initial version
v01 2006-04-03 EBD Moved PI location back to position 1 -
v3.1 of XMLmind is better with them at this location.
v02 2007-03-07 AH removed extraneous nested_list attribute,
other minor corrections
v03 2007-03-09 EBD Added comments on null IANA sections and fixed heading capitalization.
Modified comments around figure to reflect non-implementation of
figure indent control. Put in reference using anchor="DOMINATION".
Fixed up the date specification comments to reflect current truth.
v04 2007-03-09 AH Major changes: shortened discussion of PIs,
added discussion of rfc include.
v05 2007-03-10 EBD Added preamble to C program example to tell about ABNF and alternative
images. Removed meta-characters from comments (causes problems). -->
</back>
</rfc>
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