One document matched: draft-ietf-behave-syslog-nat-logging-03.xml
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<rfc category="std" docName="draft-ietf-behave-syslog-nat-logging-03" 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>Syslog Format for NAT Logging</title>
<!-- add 'role="editor"' below for the editors if appropriate -->
<author fullname="Zhonghua Chen" initials="Z." surname="Chen">
<organization>China Telecom</organization>
<address>
<postal>
<street></street>
<city></city>
<code></code>
<country>P.R. China</country>
</postal>
<phone></phone>
<email>18918588897@189.cn</email>
</address>
</author>
<author fullname="Cathy Zhou" initials="C." surname="Zhou">
<organization>Huawei Technologies</organization>
<address>
<postal>
<street>Bantian, Longgang District</street>
<city>Shenzhen</city>
<code>518129</code>
<country>P.R. China</country>
</postal>
<phone></phone>
<email>cathy.zhou@huawei.com</email>
</address>
</author>
<author fullname="Tina Tsou" initials="T." surname="Tsou">
<organization>Huawei Technologies (USA)</organization>
<address>
<postal>
<street>2330 Central Expressway</street>
<city>Santa Clara</city>
<region>CA</region>
<code>95050</code>
<country>USA</country>
</postal>
<phone>+1 408 330 4424</phone>
<email>tina.tsou.zouting@huawei.com</email>
</address>
</author>
<author initials="T." surname="Taylor" fullname="T. Taylor" role="editor">
<organization>Huawei Technologies</organization>
<address>
<postal>
<street></street>
<city>Ottawa</city>
<region></region>
<code></code>
<country>Canada</country>
</postal>
<phone></phone>
<email>tom.taylor.stds@gmail.com</email>
</address>
</author>
<date year="2013" />
<!-- If the month and year are both specified and are the current ones,
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<!-- Meta-data Declarations -->
<area>Transport</area>
<workgroup>Behave Working Group</workgroup>
<!-- WG name at the upperleft corner of the doc,
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<abstract>
<t>With the wide deployment of Carrier Grade NAT (CGN) devices, the
logging of NAT-related events has become very important for various
operational purposes. The logs may be required for troubleshooting, to
identify a host that was used to launch malicious attacks, and/or for
accounting purposes. This document identifies the events that need to be
logged and the parameters that are required in the logs depending on the
context in which the NAT is being used. It goes on to standardize formats
for reporting these events and parameters using SYSLOG (RFC 5424). A
companion document specifies formats for reporting the same events and
parameters using IPFIX (RFC 5101). Applicability statements are provided
in this document and its companion to guide operators and implementors in
their choice of which technology to use for logging.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t> Operators already need to record the addresses assigned to
subscribers at any point in time, for operational and regulatory
reasons. When operators introduce NAT devices which support address
sharing (e.g., Carrier Grade NATs (CGNs)) into their network,
additional information has to be logged. This document and
<xref target="I-D.behave-ipfix-nat-logging"/> are provided in order to
standardize the events and parameters to be recorded, using
SYSLOG <xref target="RFC5424"/> and IPFIX <xref target="RFC5101"/>
respectively. The content proposed to be logged by the two documents
is exactly the same, but as will be seen, the choice of which to use
in a given scenario is an engineering issue. </t>
<t>Detailed logging requirements will vary depending on the context in
which they are used. For example, different methods for transition
from IPv4 to IPv6 require different events and different parameters to
be logged. <xref target="deploy"/> covers this topic.</t>
<t><xref target="events"/> provides a more
detailed description of the events that need logging and the parameters
that may be required in the logs.</t>
<t>The use of SYSLOG <xref target="RFC5424"/> has advantages and
disadvantages compared with the use of IPFIX <xref target="RFC5101"/>.
<xref target="applic"/> provides a statement of applicability for the
SYSLOG approach.</t>
<t><xref target="recFMT"/> specifies SYSLOG record formats for logging
of the events and parameters described in <xref target="events"/>. The
definitions provide the flexibility to vary actual log contents based
on the requirements of the particular deployment.</t>
<section title="Terminology">
<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">
"Key words for use in RFCs to Indicate Requirement Levels"</xref>.</t>
<t>This document uses the terms "session" and Binding
Information Base (BIB) as they are defined in Section 2 of <xref
target="RFC6146"/>. Note that this definition of "session" is
destination-specific, where the original definition of a NAT session in
<xref target="RFC2663"/> is destination-independent.</t>
<t>This document uses the term "address mapping" to denote the initial
logical step required to set up a session, as described in <xref
target="realms"/>. It uses the term "transport binding" to denote the
content of a BIB entry.</t>
<t>Except where a clear distinction is necessary, this document uses the
abbreviation "NAT" to encompass both Network Address Translation (NAT in
the strict sense) and Network Address and Port Translation (NAPT). The
event report descriptions provided in this document apply to NAPT, and
can be simplified for pure NAT operation.</t>
</section>
</section> <!-- Introduction -->
<section anchor="deploy" title="Deployment Considerations">
<section anchor="statDyn" title="Static and Dynamic NATs">
<t>A NAT controls a set of resources in the form of one or more pools of
external addresses. If the NAT also does port translation (i.e., it is a
NAPT), it also controls the sets of UDP and TCP port numbers and ICMP
identifiers associated with each external address. </t>
<t>Logging requirements for a NAT depend heavily on its resource
allocation strategy. NATs can be classed as static or dynamic depending
on whether the resources provided to individual users are pre-configured
or allocated in real time as the NAT recognizes new flows. </t>
<t>Static assignments can be logged at configuration time by the NAT or
by network infrastructure. The logging volume associated with static
assignments will be relatively low, of the order of the volume of user
logons. As discussed below, static assignments are typically associated
with IPv6 transition methods rather than traditional NAT. The details of
what to log will depend on the transition method concerned. </t>
<t>Dynamic assignments typically require both more detail in the logs
and a higher volume of logs in total. A traditional Network Address Port
Translator (NAPT) as described in <xref target="RFC3022"/> and following
the recommendations of <xref target="RFC4787"/> and <xref
target="RFC5382"/> will generate a new mapping each time it encounters a
new internal <address, port> combination.</t>
<t>For statistical reasons, static assignments support lower address
sharing ratios than fully dynamic assignments as exemplified by the
traditional NAPT. The sharing ratio can be increased while restraining
log volumes by assigning ports to users in multi-port increments as
required rather than assigning just one port at a time. A subscriber may
start with no initial allocation, or may start with an initial permanent
allocation to which temporary increments are added when the initial set
is all being used. See <xref target="RFC6264"/> and
<xref target="I-D.tsou-behave-natx4-log-reduction"/> for details. If
this strategy is followed, logging will be required only when an
increment is allocated or reclaimed rather than every time an internal
<address, port> combination is mapped to an external <address,
port>. </t>
</section> <!-- statDyn -->
<section anchor="realms" title="Realms and Address Pools">
<t>A realm defines the scope within which a specific set of addresses
are unique. In general these will be IPv4 or IPv6 addresses, but not
necessarily. A counter-example specifically addressed by this document
is the case of Gateway-Initiated DS-Lite <xref target="RFC6674"/>,
where individual host sites are identified by 16-bit Softwire
Identifiers. See further discussion in <xref target="transition"/> and
<xref target="genAddr"/>.</t>
<t>Table [proposed] in the NAT-MIB <xref target="I-D.Behave-NAT-MIB"/>
provides a mapping between each realm identifier and the Virtual Routing
Function (VRF) instance, VLAN identifier, or Gateway-Initiated DS-Lite
context, if any, with which it is associated. </t>
<t>From the point of view of a specific NAT session, only two realms
are involved: an internal realm and an external realm. However, the
NAT as a whole may support a number of realms, for example:
<list style="symbols">
<t>multiple internal realms with overlapping address spaces;</t>
<t>an external IPv4 public realm; and/or</t>
<t>an external IPv6 public realm.</t>
</list>
</t>
<t>As described in [RFC6146], for example, setting up a NAT session
proceeds in a series of logical steps. The first step in particular may
not be implemented explicitly in a given implementation, but logically
it has to happen before the next step can be taken.
<list style="numbers">
<t>An address mapping is created between the internal realm and
an external realm chosen based on information in the triggering packet
or administrative request.</t>
<t>Using that address mapping, a transport binding is created between
specific transport endpoints (e.g., between specific port values) in
the two realms for the protocol required by the session, and added to
the Binding Information Base (BIB).</t>
<t>Setup of the session is completed by mapping the destination
address and port (if necessary) into the selected external realm.</t>
</list>
</t>
<t>This section is concerned only with the address mapping step. That
step is always triggered either by a packet outgoing from the internal
host to a given destination, or by administrative action providing
equivalent information. The external realm for the mapping is chosen
based on the destination.</t>
<t>To summarize where we are: an address mapping binds an internal
address with an external address in a selected external realm.
One address mapping can serve as the basis for one to many transport
bindings in the BIB, and one BIB entry can serve as the basis for one to
many sessions. A single internal address may be associated with multiple
address mappings at one time.</t>
<section anchor="pools" title="Address Pools">
<t>An address pool is a mechanism for configuring the set of addresses
to which a given internal address can be mapped in a given realm. The
pool may be used simply to ration the available addresses within that
realm, or may be selected for other reasons such as to add additional
semantics (e.g., type of service required) to the external address
within the target realm. Clearly a given internal address may be mapped
into more than one address pool at a given time.</t>
<t>The model of an address pool assumed in this document and in the
NAT MIB [I-D.Behave-NAT-MIB] is that the pool offers a fixed range of
port/ICMP identifier values, the same over all addresses within the
pool. How these are allocated to individual transport bindings in the
BIB depends on the pooling behaviour. With a pooling behaviour of
"arbitrary" [RFC4787], the NAT can select any address in the pool with
a free port value for the required protocol and map the internal address
to it. With the recommended pooling behaviour of "paired" [RFC4787],
the NAT restricts itself to finding a free port at the address to
which the internal address is already mapped, if there is one.</t>
<t>From this description, one can see that ports are a limited
resource, subject to exhaustion at the pool level and, with "paired"
behaviour, at the level of the individual address. Log events are
defined in <xref target="poolThresh"/> that allow monitoring of port
utilization at the pool level. <xref target="mgmtConsid"/> discusses
how the thresholds for triggering these events should be varied
depending on pooling behaviour.</t>
</section> <!-- pools -->
</section> <!-- realms -->
<section anchor="transition" title="NAT Logging Requirements For Different Transition Methods">
<t>A number of transition technologies have been or are being
developed to aid in the transition from IPv4 to IPv6. 6rd
<xref target="RFC5969"/> and DS-Lite <xref target="RFC6333"/> are at
the deployment stage. Several 'stateless' technologies: Public IPv4
over IPv6 <xref target="I-D.softwire-public-4over6"/>, MAP-E
<xref target="I-D.softwire-map"/>, and Lightweight 4over6
<xref target="I-D.softwire-lw4over6"/> have seen experimental
deployment and are in the process of being standardized at the time of
writing of this document. </t>
<t>Of the technologies just listed, 6rd and Public IPv4 over IPv6 do
not involve NATs and hence need not be considered further. The other
techniques involve NAT at the customer edge, at the border router, or
both, and hence are in scope.</t>
<t>A DS-Lite Address Family Transition Router (AFTR) includes a
large-scale session-stateful NAT44 processing potentially
millions of sessions per second. The special character of AFTR
operation over that of a traditional NAT44 is that the source IPv4
addresses of the internal hosts may not be unique. As a consequence,
the session tables need to include an alternative identifier associated
with the subscriber host. For basic DS-Lite, this will be the IPv6
address used to encapsulate the packets outgoing from the host. See
Section 6.6 of <xref target="RFC6333"/>. For gateway-initiated DS-Lite
<xref target="RFC6674"/>, an identifier associated with the incoming
tunnel from the host is used instead.</t>
<t>The DS-Lite customer edge equipment (the 'B4') may also perform
NAT44 functions, similar to the functions performed
by traditional NAT44 devices.</t>
<t>As a NAT44, the DS-Lite AFTR may be fully dynamic, or may allocate
ports in increments as described in the previous section. </t>
<t>Lightweight 4over6 <xref target="I-D.softwire-lw4over6"/> and MAP-E
<xref target="I-D.softwire-map"/> both require NAT44 operation at the
customer equipment (unified CPE,
<xref target="I-D.softwire-unified-cpe"/>). In both cases the resource
allocation strategy is static. Thus any logging of resource allocation
for these two transition techniques can be done by the network at
configuration time.</t>
<section anchor="genAddr" title="IP Addresses and Generalized Addresses">
<t>In the event reports described below, external addresses and
destination addresses will always be true IPv4 or IPv6 addresses. Source
addresses of outgoing packets before mapping will also be IP addresses,
but will not always be meaningful because they will not be unique within
their realm. This is true in particular of some of the transition methods
described in the previous section.</t>
<t>For this reason, the event report descriptions introduce the term
"generalized address" to describe internal addresses (as opposed to
source addresses within packets). The detailed description of the
encoding of a generalized address in <xref target="params"/> provides for
an address type, address/prefix value, and address/prefix length,
similarly to the encoding of an IP address. However, the range of
generalized address types is expanded to support the following:
<list style="symbols">
<t>For traditional NATs, the source IPv4 address (for NAT44) or IPv6
address (for NAT64) is sufficient.</t>
<t>For the DS-Lite, Lightweight 4over6 or MAP-E transition methods,
the subscriber site can be identified by the IPv6 tunnel endpoint
prefix or address provisioned to that site.</t>
<t>Gateway-initiated DS-Lite uses the combination of a 32-bit context
identifier (CID) and a softwire identifier (SWID). Several different
realizations of these identifiers are described in Section 6 of <xref
target="RFC6674"/>. From the point of view of this document, the CID is
represented by a realm identifier, leaving the SWID as the value of the
generalized address itself.</t>
</list>
</t>
</section> <!-- genAddr -->
</section> <!-- transition -->
<section anchor="PCP" title="The Port Control Protocol (PCP)">
<t>The Port Control Protocol (PCP) <xref target="RFC6887"/> and
its port set extension <xref target="I-D.pcp-port-set"/> can be viewed
as a way to provision ports by other means. However, PCP can be invoked on a
per-flow basis, so the volume of logs generated by a PCP server can be
closer to the volume associated with a fully dynamic NAT. The volume
really depends on how PCP is being used in a specific network.</t>
</section> <!-- PCP -->
<section anchor="edgeLogs" title="Logging At the Customer Edge">
<t>Logging at the customer edge (or at the ISP edge for NATs
protecting the ISP's internal networks) may be done by the customer
for purposes of internal management, or by the ISP for its own
administrative and regulatory purposes. Given the likelihood of a high
internal community of interest, it is possible but unlikely that a NAT
at the edge of a large enterprise network processes a number of new
packet flows per second which is comparable to the volume handled by a
carrier grade NAT. Most customer edge NATs will handle a much smaller
volume of flows.</t>
</section> <!-- edgeLogs -->
</section> <!-- deploy -->
<section anchor="events" title="NAT-Related Events and Parameters">
<t>The events which follow were initially gleaned, in the words of the
authors of <xref target="I-D.behave-ipfix-nat-logging"/>, from <xref
target="RFC4787"/> and <xref target="RFC5382"/>. Some details were
subsequently informed by the discussion in <xref
target="deploy"/> and by provisions within the NAT MIB
<xref target="I-D.Behave-NAT-MIB"/>. Section 4 of <xref target="RFC6888"/>
also provides a brief statement of logging requirements for carrier grade
NATs.</t>
<t>Since the present document deals with SYSLOG rather
than IPFIX, the timestamp and the event type will appear in the log
header rather than as an explicit part of the structured data portion
of the log. Hence they are omitted from the parameter tabulations that
follow. </t>
<t>The listed parameters include an optional triggering NAT procedure in
each case. The triggering NAT procedure is an implementation-defined
string indicating the type of NAT function (e.g., NAT44) being applied in
association with the reported event. The same device can offer different
functions depending on the particular packets being processed. The
triggering NAT procedure is most relevant when address mappings are
created, but if address mapping events are not reported (i.e., because
pooling behaviour is "arbitrary" <xref target="RFC4787"/>),
implementations MAY choose to report it for BIB entry or session
events.</t>
<section anchor="sessCrDe" title="NAT Session Creation and Deletion">
<t>A NAT session creation or deletion event is logged when a transport
binding is further bound to or unbound from a specific destination
address and port in the external realm. One to many sessions can be
based on the same transport binding.</t>
<t>Implementations MUST NOT report session creation and deletion
events unless destination logging is enabled (see discussion below).</t>
<t>The following specific events are defined:
<list style="symbols">
<t>NAT session creation</t>
<t>NAT session deletion</t>
</list>
</t>
<t>These take the same parameters for all types of NAT. Parameters
"internal realm" through "protocol identifier" capture the underlying
transport binding. The destination IP address and port and possibly the
trigger are unique to the session. If the destination IP and port do not
require remapping into the external realm, the internal values are
redundant and SHOULD be omitted from the report. So long as the
underlying BIB entry exists, the internal values can in any event be
retrieved from the natMappingTable in the NAT MIB
<xref target="I-D.Behave-NAT-MIB"/> using the combination of protocol,
external realm, external destination address, and external destination
port as key.
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm (MANDATORY);</t>
<t>Generalized internal address (MANDATORY);</t>
<t>Internal port or ICMP identifier (MANDATORY);</t>
<t>External realm (MANDATORY);</t>
<t>External IP address (MANDATORY);</t>
<t>External port or ICMP identifier (MANDATORY);</t>
<t>Protocol identifier (MANDATORY);</t>
<t>Internal destination IP address (as given in outgoing packets)
(OPTIONAL);</t>
<t>Internal destination port or ICMP identifier (as given in
outgoing packets) (OPTIONAL);</t>
<t>External destination IP address (as given in outgoing packets)
(MANDATORY);</t>
<t>External destination port or ICMP identifier (as given in
outgoing packets) (MANDATORY);</t>
<t>Trigger for session creation or deletion (OPTIONAL):
<list style="symbols">
<t>outgoing packet received; </t>
<t>incoming packet received;</t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>); or</t>
<t>deletion of the underlying BIB entry.</t>
</list>
</t>
</list>
</t>
<section anchor="destLog" title="Destination Logging">
<t>The logging of destination address and port is generally
undesirable, for several reasons. <xref target="RFC6888"/> recommends
against destination logging because of the privacy issues it creates.
From an operator's point of view, destination logging is costly not
just because of the volume of logs it will generate, but because the
NAT now has to carry additional session state so that it only needs to
log once per session between two transport end points rather than
logging every packet. Finally, <xref target="RFC4787"/>, etc.
recommend the use of endpoint-independent mapping to maximize the
ability of applications to operate through the NAT. In that case, most
of the contents of the session creation event report will be repeated
for one destination after another.</t>
<t>One possibility is that the implementation provides the operator
with the ability to log destinations only for particular subscribers
or particular mapped addresses on a special study basis. This facility
could be used for trouble-shooting or malicious activity tracing in
particular cases as required. If such a capability is provided, the
implementation MUST report session creation and deletion events for
sessions matching the specified criteria, but MUST NOT report these
events for other sessions.</t>
</section> <!-- destLog -->
</section> <!-- sessCrDe -->
<section anchor="BIBCrDe" title="Binding Information Base Entry Creation and Deletion">
<t>A transport mapping as recorded in the Binding Information Base (BIB)
corresponds to the older definition of NAT session as defined in Section
2.3 of <xref target="RFC2663"/>. The BIB entry creation or deletion
event reports the addition or deletion of a mapping between an internal
transport endpoint and an external transport address. The event report
provides the same information as the session creation/deletion event,
except for the destination-related fields in the latter. </t>
<t>Particularly with endpoint-independent mapping behaviour <xref
target="RFC4787"/>, one BIB entry creation event is associated with
potentially many succeeding session creation events, as individual
destinations are mapped into the session table. Similarly, a BIB entry
deletion event will be associated with potentially many session deletion
events, which may have preceded it over a period of time or may occur at
the same time as a result of the BIB entry deletion.</t>
<t>Operators SHOULD disable the reporting of BIB entry creation and
deletion events when destination logging is enabled, because of the
redundancy between the BIB and session event reports. However, in the
case of endpoint-independent mapping behaviour <xref target="RFC4787"/>,
the BIB event provides a compact summary of most of the content of what
could be a large number of corresponding session events.</t>
<t>The following specific events are defined:
<list style="symbols">
<t>BIB entry creation</t>
<t>BIB entry deletion</t>
</list>
</t>
<t>These take the same parameters for all types of NAT. The internal
realm, generalized internal address, external realm, and external
address capture the underlying address mapping. The port values,
protocol, and possibly the trigger are unique to the BIB entry.
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm (MANDATORY);</t>
<t>Generalized internal address (MANDATORY);</t>
<t>Internal port or ICMP identifier (MANDATORY);</t>
<t>External realm (MANDATORY);</t>
<t>External address (MANDATORY);</t>
<t>External port or ICMP identifier (MANDATORY);</t>
<t>Protocol identifier (MANDATORY);</t>
<t>Trigger for transport mapping creation or deletion (OPTIONAL):
<list style="symbols">
<t>outgoing packet received; </t>
<t>incoming packet received;</t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>); or</t>
<t>deletion of the underlying address mapping.</t>
</list>
</t>
</list>
</t>
</section> <!-- BIBCrDe -->
<section anchor="addrBind" title="Address Mapping Creation and Deletion Events">
<t>Two specific events are provided:
<list style="symbols">
<t>Address mapping creation;</t>
<t>Address mapping deletion.</t>
</list>
</t>
<t>Address mapping is discussed in detail in <xref target="realms"/>. </t>
<t>One address mapping creation event is associated with potentially
many succeeding BIB entry creation events, as individual port values are
mapped into the BIB for specific protocols. Similarly, an address
mapping deletion event will be associated with potentially many BIB
entry deletion events, which may have preceded it over a period of time
or may occur at the same time as a result of the address unbinding.</t>
<t>The address mapping events take the following specific parameters:
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm (MANDATORY);</t>
<t>Generalized internal address (MANDATORY);</t>
<t>External realm (MANDATORY);</t>
<t>External IP address (MANDATORY).</t>
<t>Trigger for address mapping creation or deletion (OPTIONAL):
<list style="symbols">
<t>outgoing packet; </t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>); or</t>
<t>autonomous action of the NAT.</t>
</list>
</t>
</list></t>
</section> <!-- addrBind -->
<section anchor="portAssgn" title="Port Set Allocation and Deallocation">
<t>This event is recorded at a hybrid NAT whenever the set of ports
allocated to a given address mapping changes. It is assumed that when
ports are allocated in bulk, the same values are allocated for all
protocols.</t>
<t>The following specific events are defined:
<list style="symbols">
<t>Port set allocation;</t>
<t>Port set deallocation.</t>
</list>
</t>
<t>The parameters for these events are:
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm (MANDATORY);</t>
<t>Generalized internal address (MANDATORY);</t>
<t>External realm (MANDATORY);</t>
<t>External IP address (MANDATORY);</t>
<t>A set of ports available for transport mapping, newly allocated to
or deallocated from the given address mapping. The representation of a
port set is described in the next paragraph (MANDATORY).</t>
</list></t>
<t>A port set is represented by four parameters. The full set of
parameters describes a sequence of equally-spaced and equally-sized
ranges of consecutive port values. If only a single range is allocated
or deallocated, two of the parameters can be omitted. The four
parameters are:
<list style="symbols">
<t>Starting port number, the lowest port number in the entire port
set (MANDATORY);</t>
<t>Ending port number, the highest port number in the entire port
set (MANDATORY);</t>
<t>Range size, the number of port values in each range (OPTIONAL);</t>
<t>Range step, the difference between the first port number in one
range and the first port number in the immediately preceding range of
the port set (OPTIONAL).</t>
</list>
In the case of a single range, range size SHOULD be omitted
and range step MUST be omitted because it is meaningless.</t>
<t>Examples:
<list style="numbers">
<t>Two ranges, 1024-1535 and 2048-2559 are allocated. Each range
consists of 512 consecutive port numbers. The parameter values to
represent this allocation are:
<list style="symbols">
<t>starting port = 1024</t>
<t>ending port = 2559</t>
<t>range size = 512</t>
<t>range step = 1024.</t>
</list>
</t>
<t>Strictly for purposes of illustration, assume a sequence of 512
even-numbered ports is allocated, beginning at 1024, then 1026, ending
at 2046. The parameter values to represent this allocation are:
<list style="symbols">
<t>starting port = 1024</t>
<t>ending port = 2046</t>
<t>range size = 1</t>
<t>range step = 2.</t>
</list>
</t>
<t>A single range of ports is allocated, running consecutively from
1024 to 2046. The parameter values to represent this allocation
are:
<list style="symbols">
<t>starting port = 1024</t>
<t>ending port = 2046.</t>
</list>
</t>
</list>
</t>
<t>It will be necessary to use multiple event reports to report more
complex allocations or deallocations.</t>
</section> <!-- portAssgn -->
<section anchor="poolThresh" title="Address Pool High- and Low-Water-Mark Threshold Events">
<t>Two specific events provide reports on address pool utilization:
<list style="symbols">
<t>High-water-mark threshold reached or over-shot;</t>
<t>Low-water-mark threshold reached or under-shot.</t>
</list>
Depending on deployment the operator has the alternative of using the
SNMP notifications natNotifPoolWater-MarkHigh and
natNotifPoolWater-MarkLow defined in the NAT MIB
<xref target="I-D.Behave-NAT-MIB"/> rather than logging these events.
</t>
<t>Address pools are discussed in <xref target="pools"/>. The
natPoolTable object in the NAT MIB <xref target="I-D.Behave-NAT-MIB"/>
provides access to parameters describing the utilization level of
address-port combinations within a given pool. Since a new transport
mapping cannot be allocated unless a mappable address and a free port on
that address are available, it is important to know when the available
set of address-port combinations within a given pool is nearing
exhaustion. Hence the natPoolTable contains a high-water-mark threshold
settable by the operator. An address pool high-water-mark event report is
generated when a new mapping into the pool is triggered and aggregate
address-port utilization is equal to or greater the threshold.</t>
<t>Similarly it can be of interest to know when a pool is under-
utilized. Hence the natPoolTable also provides a low-water-mark
threshold. An address pool low-water-mark event report is generated wwhen
aggregate address-port utilization is equal to or less than the
low-water-mark threshold.</t>
<t><xref target="mgmtConsid"/> discusses factors affecting the choice
of the threshold values, taking note that the port utilization as
computed does not take account of the number of different protocols
mapped to a given port value.</t>
<t>An address pool threshold event report contains the following specific
parameters:
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Pool identifier, equal to the value of the natPoolIndex object
presented in the natPoolTable in the MIB (MANDATORY).</t>
</list>
</t>
</section> <!-- poolThresh -->
<section anchor="addrThresh" title="Global Address Mapping High-Water-Mark Threshold Event">
<t>One specific event allows monitoring of the total number of mappings
between internal and external addresses:
<list style="symbols">
<t>Address mapping high-water-mark threshold equalled or exceeded.</t>
</list>
This event report is most meaningful when the pooling type behaviour is
"paired" <xref target="RFC4787"/>, and is especially
applicable to devices implementing NAT functionality only and not port
translation. Depending on deployment, operators can choose instead to
use the SNMP notification natNotifAddrMappings defined in the NAT MIB
<xref target="I-D.Behave-NAT-MIB"/>.</t>
<t>The NAT MIB displays cumulative counts of address mappings created and
removed in the natCounters table. When the difference
between these two counters equals or exceeds the threshold
natAddrMapNotifyThreshold provided in the natLimits table the global
address binding high-water-mark threshold event is reported.</t>
<t>The specific parameters provided by this event report are:
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Current number of active address mappings, equal to the difference
between the natAddressMappingCreations and natAddressMappingRemovals
counters displayed in the natCounters table in the NAT MIB
(MANDATORY).</t>
</list>
</t>
</section> <!-- addrThresh -->
<section anchor="addrMapLim" title="Global Address Mapping Limit Exceeded">
<t>The "Global Address Mapping Limit Exceeded" event is reported when a
new address mapping is triggered but the total number of address
mappings would exceed an administrative limit if it were added. The
limit is given by object natLimitAddressMappings in the natLimits table
of the NAT MIB. MIB counters giving number of packets dropped due to
resource limitations including this one are:
<list style="symbols">
<t>globally, natResourceErrors in the natCounters table;</t>
<t>per protocol, natProtocolResourceErrors in natProtocolTable;</t>
<t>per subscriber, natSubscriberResourceErrors in natSubscribersTable.</t>
</list>
</t>
<t>The parameters for this event are:
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm (MANDATORY);</t>
<t>Generalized internal address (MANDATORY);</t>
<t>Trigger for address mapping creation (MANDATORY):
<list style="symbols">
<t>outgoing packet; </t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>).</t>
</list>
</t>
</list>
</t>
</section> <!-- addrMapLim -->
<section anchor="transThresh" title="Global Transport Mapping High-Water-Mark Threshold Event">
<t>One specific event allows monitoring of the total number of mapping
entries in the Binding Information Base (BIB):
<list style="symbols">
<t>Transport mapping high-water-mark threshold equalled or exceeded.</t>
</list>
Depending on deployment, operators can choose instead to use the SNMP
notification natNotifMappings defined in the NAT MIB
<xref target="I-D.Behave-NAT-MIB"/>.</t>
<t>The NAT MIB displays cumulative counts of mappings created in and
removed from the BIB in the natCounters table. When the difference
between these two counters equals or exceeds the threshold
natMappingsNotifyThreshold provided in the natLimits table the global
mapping high-water-mark threshold event is reported.</t>
<t>The specific parameters provided by this event report are:
<list style="symbols">
<t>Reporting device identifier (OPTIONAL);</t>
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Current number of active mappings, equal to the difference between
the natMappingCreations and natMappingRemovals counters displayed in
the natCounters table in the NAT MIB (MANDATORY).</t>
</list>
</t>
</section> <!-- transThresh -->
<section anchor="transMapLim" title="Global Transport Mapping Limit Exceeded">
<t>The "Global Transport Mapping Limit Exceeded" event is reported when
a new transport mapping (i.e., BIB entry creation) is triggered but the
total number of transport mappings would exceed an administrative limit
if it were added. The limit is given by object natLimitMappings in the
natLimits table of the NAT MIB. MIB counters giving number of packets
dropped due to resource limitations including this one are:
<list style="symbols">
<t>globally, natResourceErrors in the natCounters table;</t>
<t>per protocol, natProtocolResourceErrors in natProtocolTable;</t>
<t>per subscriber, natSubscriberResourceErrors in natSubscribersTable.</t>
</list>
</t>
<t>The parameters for this event are:
<list style="symbols">
<t>Reporting device identifier (OPTIONAL);</t>
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm (MANDATORY);</t>
<t>Generalized internal address (MANDATORY);</t>
<t>Trigger for BIB entry creation (MANDATORY):
<list style="symbols">
<t>incoming packet;</t>
<t>outgoing packet; </t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>).</t>
</list>
</t>
</list>
</t>
</section> <!-- transMapLim -->
<section anchor="subsThresh" title="Subscriber-Specific Mapping Threshold Event">
<t>An event is provided to allow monitoring of the total number of BIB
entries per subscriber:
<list style="symbols">
<t>Subscriber-specific mapping high-water-mark threshold equalled or exceeded.</t>
</list>
Depending on deployment, operators can choose instead to
use the SNMP notification natNotifSubscriberMappings defined in the NAT
MIB <xref target="I-D.Behave-NAT-MIB"/>.</t>
<t>The NAT MIB displays cumulative counts of transport mappings created
and removed per subscriber in the natSubscribersTable. When the
difference between these two counters equals or exceeds the threshold
natSubscriberMapNotifyThresh provided in that table the subscriber
mapping high-water-mark threshold event is reported.</t>
<t>The specific parameters provided by this event report are:
<list style="symbols">
<t>Reporting device identifier (OPTIONAL);</t>
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm of the subscriber (MANDATORY);</t>
<t>Generalized internal address of the subscriber (MANDATORY);</t>
<t>Current number of active transport mappings for this subscriber,
equal to the difference between the natSubscriberMappingCreations and
natSubscriberMappingRemovals counters displayed in the
natSubscribersTable table in the NAT MIB (MANDATORY).</t>
</list>
</t>
</section> <!-- subsThresh -->
<section anchor="actSubsLim" title="Global Limit On Number of Active Subscribers Exceeded">
<t>The "Global Limit On Number of Active Subscribers Exceeded" event is
reported when an address mapping is triggered (at least at the logical
level) for a subscriber with no previous active mappings, but the total
number of active subscribers would exceed an administrative limit if it
were added. The limit is given by object natLimitSubscribers in the
natLimits table of the NAT MIB. MIB counters giving number of packets
dropped due to resource limitations including this one are:
<list style="symbols">
<t>globally, natResourceErrors in the natCounters table;</t>
<t>per protocol, natProtocolResourceErrors in natProtocolTable;</t>
<t>per subscriber, natSubscriberResourceErrors in natSubscribersTable.</t>
</list>
</t>
<t>The parameters for this event are:
<list style="symbols">
<t>Reporting device identifier (OPTIONAL);</t>
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm of the rejected subscriber (MANDATORY);</t>
<t>Generalized internal address of the rejected subscriber (MANDATORY);</t>
<t>Trigger for mapping creation (MANDATORY):
<list style="symbols">
<t>outgoing packet; </t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>).</t>
</list>
</t>
</list>
</t>
</section> <!-- actSubsLim -->
<section anchor="subsMapLim" title="Subscriber-Specific Limit On Number of Transport Mappings Exceeded">
<t>The "Subscriber-Specific Limit On Number of Transport Mappings Exceeded" event is
reported when a new BIB entry is triggered, but the total
number of BIB entries for that subscriber would exceed an administrative limit if it
were added. The limit is given by object natSubscriberLimitMappings in
natSubscribersTable in the NAT MIB. MIB counters giving number of packets
dropped due to resource limitations including this one are:
<list style="symbols">
<t>globally, natResourceErrors in the natCounters table;</t>
<t>per protocol, natProtocolResourceErrors in natProtocolTable;</t>
<t>per subscriber, natSubscriberResourceErrors in natSubscribersTable.</t>
</list>
</t>
<t>The parameters for this event are:
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Internal realm of the subscriber (MANDATORY);</t>
<t>Generalized internal address of the subscriber (MANDATORY);</t>
<t>Trigger for transport mapping creation (MANDATORY):
<list style="symbols">
<t>incoming packet;</t>
<t>outgoing packet; </t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>).</t>
</list>
</t>
</list>
</t>
</section> <!-- subsMapLim -->
<section anchor="quota" title="Quota Exceeded Event">
<t>A "Quota Exceeded" event is reported when the NAT cannot allocate a
new address mapping, transport mapping, or session because an
administrative quota has been reached. Quotas may be applied on absolute
quantities or on rates. The specific types of quota capability offered
by a device are implementation dependent, hence the "Quota Exceeded"
event reports only the minimum of information needed to identify and
interpret the quota. Table [proposed] in the NAT MIB lists quota
identifiers and corresponding total counts of packets dropped because of quota
violations. This table may be extended to provide information on the
configuration of the particular quota, depending on the implementation.
</t>
<t>A number of counters within the NAT MIB record the number of packets
dropped due to quota violations:
<list style="symbols">
<t>globally, in counter natQuotaDrops in the natCounters table;</t>
<t>by protocol, in the natProtocolQuotaDrops counter in the
natProtocolTable;</t>
<t>per subscriber, in counter natSubscriberQuotaDrops in the
natSubscribersTable.</t>
</list>
</t>
<t>In the list of report parameters that follows, the internal realm and
generalized internal address MUST be provided if they are available. If
the trigger for the quota violation is a packet, the contents of the
received packet header and the realm that the packet came from MUST be
reported. If the trigger was an administrative action, the equivalent to
as much of this information as possible SHOULD be reported.
<list style="symbols">
<t>Triggering NAT procedure (OPTIONAL);</t>
<t>Quota identifier (MANDATORY);</t>
<t>Internal realm (OPTIONAL);</t>
<t>Generalized internal address (OPTIONAL);</t>
<t>Source realm for triggering packet (OPTIONAL);</t>
<t>Source IP address (OPTIONAL);</t>
<t>Source port or ICMP identifier (OPTIONAL);</t>
<t>Destination IP address (OPTIONAL);</t>
<t>Destination port (OPTIONAL);</t>
<t>Protocol (OPTIONAL);</t>
<t>Trigger for quota violation (OPTIONAL)
<list style="symbols">
<t>packet received at the NAT; </t>
<t>administrative action (e.g., via the Port Control Protocol
<xref target="RFC6887"/>).</t>
</list>
</t>
</list>
</t>
<t>In the special case where the quota addresses bulk port allocation,
the parameters listed above MUST be interpreted and populated as
follows, so as to capture the address mapping to which the ports would
have been allocated:
<list style="symbols">
<t>Internal realm and generalized internal address retain their usual
meanings;</t>
<t>Source realm and source IP address present the external realm and
address portion of the address mapping;</t>
<t>port numbers, protocol, and destination address MUST be omitted.</t>
</list>
</t>
</section> <!-- quota -->
<section anchor="fragLim" title="Global Limit On Number Of Fragments Pending Reassembly Exceeded">
<t>The "Global Limit On Number Of Fragments Pending Reassembly Exceeded"
event is reported when a new fragment is received and the number of
fragments currently awaiting reassembly is already equal to an
administrative limit. That limit is given by the natLimitFragments
object in the natLimits table. This event MUST NOT be reported unless
the NAT supports the "Receive Fragments Out of Order" behavior <xref
target="RFC4787"/>. MIB counters giving number of packets
dropped due to resource limitations including this one are:
<list style="symbols">
<t>globally, natResourceErrors in the natCounters table;</t>
<t>per protocol, natProtocolResourceErrors in natProtocolTable;</t>
<t>per subscriber, natSubscriberResourceErrors in natSubscribersTable.</t>
</list>
</t>
<t>The parameters for this event provide the contents of the IP header
of the received fragment that triggered it. If the source realm is
internal and the generalized internal address is available, it MUST also
be included.
<list style="symbols">
<t>Source realm of the packet (MANDATORY);</t>
<t>Source IP address (MANDATORY);</t>
<t>Destination IP address (MANDATORY);</t>
<t>Generalized internal address of the source (OPTIONAL).</t>
</list>
</t>
</section> <!-- fragLim -->
</section> <!-- events -->
<section anchor="applic" title="SYSLOG Applicability">
<t>The primary advantage of SYSLOG is the human readability and
searchability of its contents. In addition, it has built-in priority
and severity fields that allow for separate routing of reports
requiring management action. Finally, it has a well-developed
underpinning of transport and security protocol infrastructure.</t>
<t>SYSLOG presents two obstacles to scalability: the fact that the
records will typically be larger than records based on a binary
protocol such as IPFIX, and, depending on the architectural context,
the reduced performance of a router that is forced to do text
manipulation in the data plane. One has to conclude that for larger
message volumes, IPFIX should be preferred as the reporting medium on
the NAT itself. It is possible that SYSLOG could be used as a back-end
format on an off-board device processing IPFIX records in real time,
but this would give a limited boost to scalability. One concern
expressed in list discussion is that when the SYSLOG formatting
process gets overloaded records will be lost.</t>
<t>As a result, the key question is what the practical cutoff point is
for the expected volume of SYSLOG records, on-board or off-board the
NAT. This obviously depends on the computing power of the formatting
platform, and also on the record lengths being generated. </t>
<t>Information has been provided to the BEHAVE list at the time of
writing to the effect that one production application is generating an
average of 150,000 call detail records per second, varying in length from
500 to 1500 bytes. Capacities several times this level have been
reported involving shorter records, but this particular application
has chosen to limit the average in order to handle peaks.</t>
<t>As illustrated by the examples in <xref target="evCode"/>, typical
record sizes for the high-volume logs are in the order of 150 to 200
bytes, so throughput capacity should be higher than in the call detail
case for the same amount of computing power. In private communication,
a discussant has noted a practical limit of a few hundred thousand
SYSLOG records per second on a router.</t>
</section> <!-- applic -->
<section anchor="recFMT" title="SYSLOG Record Format For NAT Logging">
<t>This section describes the SYSLOG record format for NAT logging in
terms of the field names used in <xref target="RFC5424"/> and
specified in Section 6 of that document. In particular,
this section specifies values for the APP-NAME and MSGID fields in the
record header, the SD-ID identifying the STRUCTURED-DATA section, and
the PARAM-NAMEs and PARAM-VALUE types for the individual possible
parameters within that section. The specification is in three parts,
covering the header, encoding of the individual parameters, and encoding
of the complete log record for each event type.</t>
<section anchor="hdrFMT" title="SYSLOG HEADER Fields">
<t>Within the HEADER portion of the SYSLOG record, the priority (PRI)
level is subject to local policy, but a default value of 8x is
suggested, representing a Facility value of 10
(security/authorization) and a Severity level varying with the event
type. The suggested value by event type is shown in <xref
target="tab_events"/>. The HOSTNAME field MUST identify the NAT. The
value of the HOSTNAME field is subject to the preferences given in
Section 6.2.4 of <xref target="RFC5424"/>.</t>
<t> The values of the APP-NAME and MSGID fields in the record header
determine the semantics of the record. The APP-NAME value
"NAT" indicates that the record relates to an event reported by a NAT
device. The MSGID values indicate the individual events.
They are listed in <xref target="tab_events"/> for each of the events
defined in <xref target="events"/>. The table also shows the SD-ID
value used to label the event-specific STRUCTURED-DATA element.</t>
<texttable anchor="tab_events" title="Recommended MSGID Encodings and Default PRI Values for the Events Defined In Section 3">
<ttcol align="left">Event</ttcol>
<ttcol align="left">MSGID</ttcol>
<ttcol align="left">PRI</ttcol>
<ttcol align="left">SD-ID</ttcol>
<c>NAT session creation</c>
<c>SessAdd</c>
<c>86 info</c>
<c>NATsess</c>
<c>NAT session deletion</c>
<c>SessDel</c>
<c>86 info</c>
<c>NATsess</c>
<c>Address binding event</c>
<c>AddrBind</c>
<c>86 info</c>
<c>NATBind</c>
<c>Port allocation change</c>
<c>PtAlloc</c>
<c>86 info</c>
<c>NATPBlk</c>
<c>NAT address exhaustion</c>
<c>AddrEx</c>
<c>82 critical</c>
<c>NATAddrEx</c>
<c>NAT port exhaustion</c>
<c>PortEx</c>
<c>84 warning</c>
<c>NATPEx</c>
<c>Quota exceeded</c>
<c>Quota</c>
<c>85 notice</c>
<c>NATQEx</c>
<c>Invalid port detected</c>
<c>InvPort</c>
<c>83 error</c>
<c>NATInvP</c>
</texttable>
</section> <!-- hdrFMT -->
<section anchor="params" title="Parameter Encodings">
<t>This section describes how to encode the individual parameters that
can appear in NAT-related logs. The parameters are taken from the event
descriptions in <xref target="events"/>, and are listed in <xref
target="tab_params"/>. Formally, as will be seen in <xref
target="iana"/>, a parameter used with more than one event is registered
as multiple separate parameters, one for each event report in which it
is used. However, there is no reason to change either the PARAM-NAME or
the encoding of the PARAM-VALUE between different instances of the same
parameter.</t>
<texttable anchor="tab_params" title="Parameters Used In NAT-Related Log Reports, By PARAM-NAME">
<ttcol align="left">PARAM-NAME</ttcol>
<ttcol align="left">Parameter</ttcol>
<c>APoolId</c>
<c>Address pool identifier</c>
<c>DevID</c>
<c>reporting device identifier</c>
<c>DevTyp</c>
<c>reporting device type</c>
<c>PostS4</c>
<c>Mapped external IPv4 address</c>
<c>PostSPt</c>
<c>Mapped external port or ICMP identifier</c>
<c>PreSPt</c>
<c>Internal port or ICMP identifier</c>
<c>Proto</c>
<c>Protocol identifier</c>
<c>PScop</c>
<c>Protocol scope for quota</c>
<c>PSID</c>
<c>Port set identifier</c>
<c>PtRg</c>
<c>Range of consecutive port numbers</c>
<c>SiteID</c>
<c>Subscriber site identifier</c>
<c>SScop</c>
<c>Site scope for quota</c>
<c>TrigR</c>
<c>Address realm triggering the creation of the session</c>
<c>VLANid</c>
<c>VLAN identifier</c>
<c>VRFid</c>
<c>VPN routing and forwarding identifier</c>
</texttable>
<section anchor="APoolId" title="APoolId: Address Pool Identifier">
<t>PARAM-Value: decimal integer identifying a specific address pool at the
reporting NAT.</t>
</section> <!-- APoolId -->
<section anchor="DevID" title="DevID: Reporting Device Identifier">
<t>PARAM-VALUE: a US-ASCII string identifying the NAT or BR observing the
event which this record reports. Needed only if the necessary
identification is not provided by the HOSTNAME parameter in the log
record header. </t>
</section> <!-- DevID -->
<section anchor="DevTyp" title="DevTyp: Reporting Device Type">
<t>PARAM-VALUE: one of the values provided in the IANA SYSLOG
reporting device type registry established by this document. The
initial values in that registry are:
<list style="hanging" hangIndent="8">
<t hangText="44">NAT44 <xref target="RFC3022"/>;</t>
<t hangText="64">NAT64 <xref target="RFC6145"/> or
<xref target="RFC6146"/>;</t>
<t hangText="AFTR">DS-Lite AFTR <xref target="RFC6333"/>;</t>
<t hangText="BR">Lightweight 4over6 or MAP-E border router.</t>
</list></t>
<t>This parameter is primarily additional information for the human
reader of a log report, but could be used to provide a consistency
check on the contents of a log. Instances where parameter usage
depends on the reporting device type of the reporting NAT are noted in
<xref target="evCode"/>. </t>
</section> <!-- DevTyp -->
<section anchor="PostS4" title="PostS4: Mapped External IPv4 Address">
<t>PARAM-VALUE: IPv4 address, represented in dotted decimal form.</t>
</section> <!-- PostS4 -->
<section anchor="PostSPt" title="PostSPt: Mapped External Port or ICMP Identifier">
<t>PARAM-Value: decimal integer, port number or ICMP query
identifier.</t>
</section> <!-- PostSPt -->
<section anchor="PreSPt" title="PreSPt: Internal Port or ICMP Identifier">
<t>PARAM-Value: decimal integer, port number or ICMP query
identifier.</t>
</section> <!-- PreSPt -->
<section anchor="Proto" title="Proto: Protocol Identifier">
<t>PARAM-VALUE: an integer indicating the value of the Protocol header
field (IPv4) or Next Header field (IPv6) in the incoming packet(s)
(after decapsulation, for reporting device type "AFTR") to which the event
described by this record applies.</t>
</section> <!-- Proto -->
<section anchor="PScop" title="PScop: Protocol Scope For Quota">
<t>PARAM-VALUE: as for Proto for a specific protocol. "*" for sum over
all protocols.</t>
</section> <!-- PScop -->
<section anchor="PSID" title="PSID: Port Set Identifier">
<t>PARAM-VALUE: integer between 0 and 65535 designating a port set.
In practice the upper limit is likely to be two orders of magnitude
smaller.</t>
</section> <!-- PSID -->
<section anchor="PtRg" title="PtRg: Allocated Port Range">
<t>PARAM-VALUE: a field consisting of two decimal integers separated
by a minus sign/hyphen. The first integer is the lowest port number,
the second, the highest port number, in a range of consecutive
ports.</t>
</section> <!-- PtRg -->
<section anchor="SiteID" title="SiteID: Subscriber Site Identifier">
<t>A human-readable US-ASCII string identifying a specific host or CPE
served by the reporting device. The type of identifier depends on the
configuration of the reporting device, and is implementation and
deployment-specific. See <xref target="events"/> for a discussion of
the possible identifier types.</t>
</section> <!-- SiteID -->
<section anchor="SScop" title="SScop: Site Scope For Quota">
<t>PARAM-VALUE: "S" for single site, "M" for sum over multiple sites,
served by the same VLAN or VRF. "*" for sum over all sites served by
the NAT.</t>
</section> <!-- SScop -->
<section anchor="TrigR" title="TrigR: Realm Triggering Session Creation">
<t>PARAM-VALUE: "I" for internal, "E" for external.</t>
</section> <!-- TrigR -->
<section anchor="VLANid" title="VLANid: VLAN Identifier">
<t>PARAM-VALUE: a decimal integer representing the VLAN identifier
associated with the subscriber site.</t>
</section> <!-- VLANid -->
<section anchor="VRFid" title="VRFid: VPN Routing and Forwarding Identifier">
<t>PARAM-VALUE: a hexadecimal number representing a VPN identifier
<xref target="RFC2685"/> associated with the subscriber site. It is
RECOMMENDED that implementations be configurable to include or not
include the OUI portion of the identifier.</t>
</section> <!-- VRFid -->
</section> <!-- params -->
<section anchor="evCode" title="Encoding Of Complete Log Report For Each Event Type">
<t>This section describes the complete NAT-related contents of the logs
used to report the events listed in <xref target="tab_events"/>.</t>
<section anchor="SessCode" title="NAT Session Creation and Deletion">
<t>As shown in <xref target="tab_events"/>, the NAT session
creation event is indicated by MSG-ID set to "SessAdd". Similarly,
the NAT session deletion event is indicated by MSG-ID set to
"SessDel". For both events, the associated SD-ELEMENT is tagged by
SD-ID "NATsess". The contents of the NATsess SD-ELEMENT are shown in
<xref target="tab_NATsess"/>. The requirements for these contents are
derived from the description in <xref target="sessCrDe"/>.</t>
<texttable anchor="tab_NATsess" title="Contents Of the SD-ELEMENT Section For Logging the Session Creation and Deletion Events">
<ttcol align="left">PARAM-NAME</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Requirement</ttcol>
<c>DevTyp</c>
<c><xref target="DevTyp"/></c>
<c>OPTIONAL</c>
<c>DevID</c>
<c><xref target="DevID"/></c>
<c>OPTIONAL</c>
<c>SiteID</c>
<c><xref target="SiteID"/></c>
<c>MANDATORY</c>
<c>PostS4</c>
<c><xref target="PostS4"/></c>
<c>MANDATORY</c>
<c>Proto</c>
<c><xref target="Proto"/></c>
<c>MANDATORY</c>
<c>PreSPt</c>
<c><xref target="PreSPt"/></c>
<c>MANDATORY</c>
<c>PostSPt</c>
<c><xref target="PostSPt"/></c>
<c>MANDATORY</c>
<c>TrigR</c>
<c><xref target="TrigR"/></c>
<c>OPTIONAL</c>
</texttable>
<section anchor="sessEx" title="Examples">
<t>The first example is deliberately chosen to show how long a
complete session log might be. For this first example, assume the
log is formatted at an off-board device, which collects the
information from an AFTR. Thus HOSTNAME and DevID are both present.
IPv6 addresses are reported omitting a common /16 prefix and the IID
portion of the address (not to be too unrealistic!). All the
optional parameters are present. Note that the log could also
include other SD-ELEMENTs (e.g., timeQuality), but enough is
enough.</t>
<t>The log appears as a single record, but is wrapped between lines
for purposes of presentation.
<list style="empty">
<t><86>1 2013-05-07T22:14:15.03Z record.example.net NAT 5063 SessAdd
<vspace blankLines="0"/>
[NATsess DevTyp="AFTR" DevID="bgw211.example.net"
<vspace blankLines="0"/>
SiteID="A2E0:62" PostS4="198.51.100.127"
<vspace blankLines="0"/>
Proto="6" PreSPt="49156" PostSPt="6083" TrigR="I"]</t>
</list>
Character count: about 205.</t>
<t>The next example is perhaps more typical in size. Assume an
enterprise NAT44 generating its own logs. The optional
parameters are omitted. This is a session deletion event.
<list style="empty">
<t><86>1 2013-05-07T15:27:49.603-04:00 cerberus.example.com
<vspace blankLines="0"/>
NAT 175 SessDel [NATsess SiteID="192.0.2.5" PostS4="198.51.100.14"
<vspace blankLines="0"/>
Proto="6" PreSPt="51387" PostSPt="17865"]</t>
</list>
The character count: about 165.</t>
</section> <!-- sessEx -->
</section> <!-- SessCode -->
<section anchor="ABindCode" title="Address Binding Event">
<t>As shown in <xref target="tab_events"/>, the NAT address
binding event is indicated by MSG-ID set to "AddrBind". The associated
SD-ELEMENT is tagged by SD-ID "NATBind". The contents of the NATBind
SD-ELEMENT are shown in <xref target="tab_NATBind"/>. The requirements
for these contents are derived from the description in <xref
target="addrBind"/>.</t>
<texttable anchor="tab_NATBind" title="Contents Of the SD-ELEMENT Section For Logging the Address Binding Event">
<ttcol align="left">PARAM-NAME</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Requirement</ttcol>
<c>DevTyp</c>
<c> <xref target="DevTyp"/> </c>
<c>OPTIONAL</c>
<c>DevID</c>
<c> <xref target="DevID"/> </c>
<c>OPTIONAL</c>
<c>SiteID</c>
<c> <xref target="SiteID"/> </c>
<c>MANDATORY</c>
<c>PostS4</c>
<c> <xref target="PostS4"/> </c>
<c>MANDATORY</c>
</texttable>
<t>As an example, consider a DS-Lite AFTR <xref target="RFC6333"/>
incorporating a PCP server, where PCP is used to obtain an external
address binding and a port range. See Section 11 of <xref
target="RFC6887"/> for the address binding. (The port allocation is
shown in the next section's example.) As in the session creation
example, the first /16 prefix and the final 64 bits are omitted from
the encapsulating IPv6 address which is used as the subscriber site
identifier.
<list style="empty">
<t><86>1 2013-05-07T15:27:49.603Z yourd137mzmhow.example.net
<vspace blankLines="0"/>
NAT 68 AddrBind [NATBind SiteID="5A27:876E" PostS4="198.51.100.1"]</t>
</list>
Character count: about 125.</t>
</section> <!-- ABindCode -->
<section anchor="PBlkCode" title="Port Allocation Change">
<t>As indicated in <xref target="tab_events"/>, the port block
allocation change event is indicated by MSG-ID set to "PtAlloc". The
associated SD-ELEMENT is tagged by SD-ID "NATPBlk". The contents of
the NATPBlk SD-ELEMENT are shown in <xref target="tab_NATPBlk"/>. The
requirements for these contents are derived from the description in
<xref target="portAssgn"/>.</t>
<texttable anchor="tab_NATPBlk" title="Contents Of the SD-ELEMENT Section For Logging the Port Allocation Change Event">
<ttcol align="left">PARAM-NAME</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Requirement</ttcol>
<c>DevTyp</c>
<c><xref target="DevTyp"/></c>
<c>OPTIONAL</c>
<c>DevID</c>
<c><xref target="DevID"/></c>
<c>OPTIONAL</c>
<c>SiteID</c>
<c><xref target="SiteID"/></c>
<c>MANDATORY</c>
<c>PostS4</c>
<c><xref target="PostS4"/></c>
<c>MANDATORY</c>
<c>PtRg</c>
<c><xref target="PtRg"/></c>
<c>MANDATORY</c>
</texttable>
<t>As in the example in the previous section example, consider a DS-
Lite AFTR <xref target="RFC6333"/> incorporating a PCP server, where
PCP is used to obtain an external address binding and a port range.
See <xref target="I-D.pcp-port-set"/> for the port set part of this
operation.</t>
<t> Strictly for purposes of illustration, assume that the subscriber is
allocated two ranges of 64 consecutive values each, with the first
beginning at 2048 and the second at 4096.
<list style="empty">
<t><86>1 2013-05-07T15:27:49.751Z yourd137mzmhow.example.net
<vspace blankLines="0"/>
NAT 68 PtAlloc [NATPBlk SiteID="5A27:876E" PostS4="198.51.100.1"
<vspace blankLines="0"/>
PtRg="2048-2111" PtRg="4096-4159"]</t>
</list>
Character count: about 155.</t>
</section> <!-- PBlkCode -->
<section anchor="AExhCode" title="Address Exhaustion Event">
<t>As indicated in <xref target="tab_events"/>, the address
exhaustion event is indicated by MSG-ID set to "AddrEx". The
associated SD-ELEMENT is tagged by SD-ID "NATAddrEx". The contents of
the NATAddrEx SD-ELEMENT are shown in <xref target="tab_NATAddrEx"/>.
The requirements for these contents are derived from the description
in [event deleted].</t>
<texttable anchor="tab_NATAddrEx" title="Contents Of the SD-ELEMENT Section For Logging the Address Exhaustion Event">
<ttcol align="left">PARAM-NAME</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Requirement</ttcol>
<c>DevTyp</c>
<c><xref target="DevTyp"/></c>
<c>OPTIONAL</c>
<c>DevID</c>
<c><xref target="DevID"/></c>
<c>OPTIONAL</c>
<c>APoolId</c>
<c><xref target="APoolId"/></c>
<c>MANDATORY</c>
</texttable>
<t>The example shows this event being reported by a DS-Lite AFTR.
Note the critical priority indication at the beginning of the log.
As with the session example, we assume off-board log generation.
<list style="empty">
<t><82>1 2013-05-07T22:14:15.03Z record.example.net NAT 5063
<vspace blankLines="0"/>
AddrEx [NATAddrEx DevID="bgw211.example.net" APoolId="2"]</t>
</list>
Character count: about 120.</t>
</section> <!-- AExhCode -->
<section anchor="PortExCode" title="NAT Port Exhaustion">
<t>As indicated in <xref target="tab_events"/>, the port
exhaustion event is indicated by MSG-ID set to "PortEx". The
associated SD-ELEMENT is tagged by SD-ID "NATPEx". The contents of
the NATPEx SD-ELEMENT are shown in <xref target="tab_NATPEx"/>.
The requirements for these contents are derived from the description
in [event deleted].</t>
<texttable anchor="tab_NATPEx" title="Contents Of the SD-ELEMENT Section For Logging the Port Exhaustion Event">
<ttcol align="left">PARAM-NAME</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Requirement</ttcol>
<c>DevTyp</c>
<c><xref target="DevTyp"/></c>
<c>OPTIONAL</c>
<c>DevID</c>
<c><xref target="DevID"/></c>
<c>OPTIONAL</c>
<c>PostS4</c>
<c> <xref target="PostS4"/> </c>
<c>MANDATORY</c>
<c>Proto</c>
<c><xref target="Proto"/></c>
<c>MANDATORY</c>
</texttable>
<t>The example is straightforward.
Note the warning priority indication at the beginning of the log.
<list style="empty">
<t><84>1 2013-05-07T22:14:15.03Z cerberus.example.com NAT 5063
<vspace blankLines="0"/>
PortEx [NATPEx PostS4="198.51.100.1" Proto="6"]</t>
</list>
Character count: about 110.</t>
</section> <!-- PortExCode -->
<section anchor="quotaCode" title="Quota Exceeded">
<t>As indicated in <xref target="tab_events"/>, the quota
exceeded event is indicated by MSG-ID set to "Quota". The
associated SD-ELEMENT is tagged by SD-ID "NATQEx". The contents of
the NATQEx SD-ELEMENT are shown in <xref target="tab_NATQEx"/>.
The requirements for these contents are derived from the description
in <xref target="quota"/>.</t>
<texttable anchor="tab_NATQEx" title="Contents Of the SD-ELEMENT Section For Logging the Quota Exceeded Event">
<ttcol align="left">PARAM-NAME</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Requirement</ttcol>
<c>DevTyp</c>
<c><xref target="DevTyp"/></c>
<c>OPTIONAL</c>
<c>DevID</c>
<c><xref target="DevID"/></c>
<c>OPTIONAL</c>
<c>SScop</c>
<c><xref target="SScop"/></c>
<c>MANDATORY</c>
<c>PScop</c>
<c><xref target="PScop"/></c>
<c>MANDATORY</c>
<c>SiteID</c>
<c><xref target="SiteID"/></c>
<c>OPTIONAL</c>
<c>VLANid</c>
<c><xref target="VLANid"/></c>
<c>OPTIONAL</c>
<c>VRFid</c>
<c><xref target="VRFid"/></c>
<c>OPTIONAL</c>
</texttable>
<t>Example 1: limit on TCP sessions for a specific user site reached
at an AFTR with off-board log generation.
<list style="empty">
<t><85>1 2013-05-07T22:14:15.03Z record.example.net NAT 5063
<vspace blankLines="0"/>
Quota [NATQEx DevID="bgw211.example.net" SScop="S" PScop="6"
<vspace blankLines="0"/>
SiteID="A2E0:62"]</t>
</list>
Character count: about 135.</t>
<t>Example 2: global limit on number of sessions for all subscribers
served by the same VLAN.
<list style="empty">
<t><85>1 2013-05-07T15:27:49.603-04:00 cerberus.example.com
<vspace blankLines="0"/>
NAT 175 Quota [NATQEx SScop="M" PScop="*" VLANid="1246"]</t>
</list>
Character count: about 115.</t>
<t>Example 3: limit on total number of sessions for TCP.
<list style="empty">
<t><85>1 2013-05-07T15:27:49.603-04:00 cerberus.example.com
<vspace blankLines="0"/>
NAT 175 Quota [NATQEx SScop="*" PScop="6"]</t>
</list>
Character count: about 100.</t>
</section> <!-- quotaCode -->
</section> <!-- evCode -->
</section> <!-- recFMT -->
<section anchor="IANA" title="IANA Considerations">
<t>This document requests IANA to make the following assignments to
the SYSLOG Structured Data ID Values registry. RFCxxxx refers to the
present document when approved.</t>
<texttable anchor="iana" title="NAT-Related STRUCTERED-DATA Registrations">
<ttcol align="left">Structured Data ID</ttcol>
<ttcol align="left">Structured Data Parameter</ttcol>
<ttcol align="left">Required or Optional</ttcol>
<ttcol align="left">Reference</ttcol>
<c>NATsess</c>
<c></c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevTyp</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>SiteID</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PostS4</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>Proto</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PreSPt</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PostSPt</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>TrigR</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>NATBind</c>
<c></c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevTyp</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>SiteID</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PostS4</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>NATPBlk</c>
<c></c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevTyp</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>SiteID</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PostS4</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PtRg</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>NATAddrEx</c>
<c></c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevTyp</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>APoolId</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>NATPEx</c>
<c></c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevTyp</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>PostS4</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>Proto</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>NATQEx</c>
<c></c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevTyp</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>SScop</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PScop</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>SiteID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>VLANid</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>VRFid</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>----</c>
<c>NATInvP</c>
<c></c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>DevID</c>
<c>OPTIONAL</c>
<c>RFCxxxx</c>
<c></c>
<c>SiteID</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
<c></c>
<c>PSID</c>
<c>MANDATORY</c>
<c>RFCxxxx</c>
</texttable>
</section>
<section anchor="mgmtConsid" title="Management Considerations">
<t>To come.</t>
</section> <!-- mgmtConsid -->
<section anchor="Security" title="Security Considerations">
<t>When logs are being recorded for regulatory reasons, preservation
of their integrity and authentication of their origin is essential. To
achieve this result, it is RECOMMENDED that the operator deploy
<xref target="RFC5848"/>. </t>
<t>Access to the logs defined here while the reported assignments are
in force could improve an attacker's chance of hijacking a session
through port-guessing. Even after an assignment has expired, the
information in the logs SHOULD be treated as confidential, since, if
revealed, it could help an attacker trace sessions back to a
particular subscriber or subscriber location. It is therefore
RECOMMENDED that these logs be transported securely, using <xref
target="RFC5425"/>, for example, and that they be stored securely at
the collector.</t>
</section>
</middle>
<back>
<references title="Normative References">
&RFC2663;
&RFC2685;
&RFC5424;
&RFC5425;
&RFC5848;
&RFC5952;
&RFC6145;
&RFC6146;
&RFC2119;
</references>
<references title="Informative References">
&RFC3022;
&RFC4787;
&RFC5101;
&RFC5382;
&RFC5969;
&RFC6264;
&RFC6333;
&RFC6674;
&RFC6887;
&RFC6888;
<reference anchor="I-D.behave-ipfix-nat-logging">
<front>
<title>IPFIX Information Elements for logging NAT Events (Work in progress)</title>
<author initials="S." surname="Sivakumar" fullname="S. Sivakumar">
<organization>Cisco Systems</organization>
</author>
<author initials="R." surname="Penno" fullname="R. Penno">
<organization>Cisco Systems</organization>
</author>
<date month="March" year="2013"/>
</front>
</reference>
<reference anchor="I-D.softwire-public-4over6">
<front>
<title>Public IPv4 over IPv6 Access Network (Work in progress)</title>
<author initials="Y." surname="Cui" fullname="Y. Cui">
<organization>Tsinghua University</organization>
</author>
<author initials="J." surname="Wu" fullname="J. Wu">
<organization>Tsinghua University</organization>
</author>
<author initials="P." surname="Wu" fullname="P. Wu">
<organization>Tsinghua University</organization>
</author>
<author initials="O." surname="Vautrin" fullname="O. Vautrin">
<organization>Juniper Networks</organization>
</author>
<author initials="Y." surname="Lee" fullname="Y. Lee">
<organization>Comcast</organization>
</author>
<date month="February" year="2013"/>
</front>
</reference>
<reference anchor="I-D.softwire-map">
<front>
<title>Mapping of Address and Port with Encapsulation (MAP) (Work in progress)</title>
<author initials="O." surname="Troan" fullname="O. Troan">
<organization>Cisco Systems</organization>
</author>
<author initials="W." surname="Dec" fullname="W. Dec">
<organization>Cisco Systems</organization>
</author>
<author initials="X." surname="Li" fullname="X. Li">
<organization>CERNET Center/Tsinghua University</organization>
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<author initials="C." surname="Bao" fullname="C. Bao">
<organization>CERNET Center/Tsinghua University</organization>
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<organization>SoftBank Telecom</organization>
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<organization>IP Infusion</organization>
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<date month="March" year="2013"/>
</front>
</reference>
<reference anchor="I-D.softwire-lw4over6">
<front>
<title>Lightweight 4over6: An Extension to the DS-Lite Architecture (Work in progress)</title>
<author initials="Y." surname="Cui" fullname="Y. Cui">
<organization>Tsinghua University</organization>
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<organization>China Telecom</organization>
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<organization>France Telecom</organization>
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<organization>Comcast</organization>
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<organization>Deutsche Telekom AG</organization>
</author>
<date month="April" year="2013"/>
</front>
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<reference anchor="I-D.softwire-unified-cpe">
<front>
<title>Unified IPv4-in-IPv6 Softwire CPE (Work in progress)</title>
<author initials="M." surname="Boucadair" fullname="M. Boucadair">
<organization>France Telecom</organization>
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<organization>Deutsche Telekom</organization>
</author>
<date month="March" year="2013"/>
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<reference anchor="I-D.tsou-behave-natx4-log-reduction">
<front>
<title>Port Management To Reduce Logging In
Large-Scale NATs (Work in progress)</title>
<author fullname="Tina Tsou" initials="T." surname="Tsou">
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<organization>China Telecom</organization>
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<organization>Huawei Technologies</organization>
</author>
<date month="May" year="2013"/>
</front>
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<reference anchor="I-D.pcp-port-set">
<front>
<title>Port Control Protocol (PCP) Extension for Port Set Allocation (Work in progress)</title>
<author initials="Q." surname="Sun" fullname="Q. Sun">
<organization>China Telecom</organization>
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<organization>France Telecom</organization>
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<organization>Cisco Systems</organization>
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<organization>Huawei Technologies</organization>
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<organization>Huawei Technologies (USA)</organization>
</author>
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<organization>Viagenie</organization>
</author>
<date month="March" year="2013"/>
</front>
</reference>
<reference anchor="I-D.Behave-NAT-MIB">
<front>
<title>Additional Managed Objects for Network Address Translators (NAT) (Work in progress)</title>
<author initials="S." surname="Perreault">
<organization>Viagenie</organization>
</author>
<author initials="T." surname="Tsou">
<organization>Huawei</organization>
</author>
<author initials="S." surname="Sivakumar">
<organization>Cisco Systems</organization>
</author>
<date month="July" year="2013"/>
</front>
</reference>
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 01:18:49 |