One document matched: draft-ietf-dime-nat-control-09.xml
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<rfc category="std" docName="draft-ietf-dime-nat-control-09" 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="Diameter NAT Control Application">Diameter Network Address
and Port Translation Control Application</title>
<!-- add 'role="editor"' below for the editors if appropriate -->
<!-- Another author who claims to be an editor -->
<author fullname="Frank Brockners" initials="F." surname="Brockners">
<organization>Cisco</organization>
<address>
<postal>
<street>Hansaallee 249, 3rd Floor</street>
<!-- Reorder these if your country does things differently -->
<city>DUESSELDORF</city>
<region>NORDRHEIN-WESTFALEN</region>
<code>40549</code>
<country>Germany</country>
</postal>
<email>fbrockne@cisco.com</email>
<!-- uri and facsimile elements may also be added -->
</address>
</author>
<author fullname="Shwetha Bhandari" initials="S." surname="Bhandari">
<organization>Cisco</organization>
<address>
<postal>
<street>Cessna Business Park, Sarjapura Marathalli Outer Ring
Road</street>
<city>Bangalore, KARNATAKA 560 087</city>
<country>India</country>
</postal>
<email>shwethab@cisco.com</email>
</address>
</author>
<author fullname="Vaneeta Singh" initials="V." surname="Singh">
<organization></organization>
<address>
<postal>
<street>18, Cambridge Road</street>
<city>Bangalore 560008</city>
<country>India</country>
</postal>
<email>vaneeta.singh@gmail.com</email>
</address>
</author>
<author fullname="Victor Fajardo" initials="V." surname="Fajardo">
<organization>Telcordia Technologies</organization>
<address>
<postal>
<street>1 Telcordia Drive #1S-222</street>
<city>Piscataway, NJ 08854</city>
<country>USA</country>
</postal>
<email>vf0213@gmail.com</email>
</address>
</author>
<date day="10" month="July" year="2011" />
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<area>General</area>
<workgroup>Internet Engineering Task Force</workgroup>
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<abstract>
<t>This document describes the framework, messages, and procedures for
the Diameter Network address and port translation Control Application.
This Diameter application allows per endpoint control of Network Address
Translators and Network Address and Port Translators, which are added to
networks to cope with IPv4-address space depletion. This Diameter
application allows external devices to configure and manage a Network
Address Translator device - expanding the existing Diameter-based AAA
and policy control capabilities with a Network Address Translators and
Network Address and Port Translators control component. These external
devices can be network elements in the data plane such as a Network
Access Server, or can be more centralized control plane devices such as
AAA-servers. This Diameter application establishes a context to commonly
identify and manage endpoints on a gateway or server, and a Network
Address Translator and Network Address and Port Translator device. This
includes, for example, the control of the total number of Network
Address Translator bindings allowed or the allocation of a specific
Network Address Translator binding for a particular endpoint. In
addition, it allows Network Address Translator devices to provide
information relevant to accounting purposes.</t>
</abstract>
</front>
<middle>
<section title="Introduction" toc="default">
<t>Internet service providers have started to deploy Network Address
Translators (NATs) and Network Address and Port Translators (NAPTs) in
their networks to deal with the depletion of available public IPv4
addresses. This document defines a Diameter application allowing
providers to control the behavior of these NAT and NAPT devices. The use
of a Diameter application allows for simple integration into the
existing Authentication, Authorization and Accounting (AAA) environment
of a provider.</t>
<t>The Diameter Network address and port translation Control Application
(DNCA) offers the following capabilities:</t>
<t><list style="numbers">
<t>Limits or defines the number of NAPT/NAT bindings made available
to an individual end point or user. The main motivation for
restricting the number of bindings on a per end point basis is to
protect the service of the service provider against denial of
service attacks. If multiple end points share a single public IP
address, these end points can share fate. If one end point would
(either intentionally, or due to mis-behavior, mis-configuration,
mal-ware, etc.) be able to consume all available bindings for a
given single public IP address, service would be hampered (or might
even become unavailable) for those other end points sharing the same
public IP address. The efficiency of a NAPT deployment depends on
the maximum number of bindings an end point could use. Given that
the typical number of bindings an end point uses depends on the type
of end point (e.g. a personal computer of a broadband user is
expected to use a higher number of bindings than a simple mobile
phone) and a NAPT device is often shared by different types of end
points, it is desirable to actively manage the maximum number of
bindings.</t>
<t>Supports the allocation of specific NAPT/NAT bindings. Two types
of specific bindings can be distinguished:<list style="symbols">
<t>Allocation of a pre-defined NAT binding: Both the internal
and external IP address and port pair are specified within the
request. Some deployment cases, such as access to a web-server
within a user’s home network with IP address and port,
benefit from statically configured bindings.</t>
<t>Allocation of an external IP address for a given internal IP
address: The allocated external IP address is reported back to
the requestor. In some deployment scenarios, the application
requires immediate knowledge of the allocated binding for a
given internal IP address but does not control the allocation of
the external IP address; for example, SIP-proxy server
deployments.</t>
</list></t>
<t>Defines the external address pool(s) to be used for allocating an
external IP address: External address pools can either be
pre-assigned at the NAPT/NAT device, or specified within a request.
If pre-assigned address pools are used, a request needs to include a
reference to identify the pool. Otherwise, the request contains a
description of the IP address pool(s) to be used; for example, a
list of IP-subnets. Such external address pools can be used to
select the external IP address in NAPT/NAT bindings for multiple
subscribers.</t>
<t>Generates reports and accounting records: Reports established
bindings for a particular user. The collected information is used by
accounting systems for statistical purposes.</t>
<t>Queries and retrieves details about bindings on demand: This
feature complements the previously mentioned accounting
functionality (see item 4).</t>
<t>Identifies a subscriber or endpoint on multiple network devices
(NAT/NAPT device, the AAA-server, or the Network Access Server
(NAS)): Endpoint identification is facilitated through a Global
Endpoint ID. Endpoints are identified through a single or a set of
classifiers, such as IP address, Virtual Local Area Network (VLAN)
identifier, or interface identifier which uniquely identify the
traffic associated with a particular global endpoint.</t>
</list></t>
<t>This document is structured as follows: Section 2 lists terminology,
while Section 3 provides an introduction to DNCA and its overall
deployment framework. Sections 4 to 8 cover DNCA specifics, with Section
4 describing session management, Section 5 the use of the Diameter base
protocol, Section 6 new commands, Section 7 AVPs used, and Section 8
accounting aspects. Section 9 presents an AVP occurence table. IANA and
security considerations are addressed in Sections 10 and 11.</t>
</section>
<section anchor="Conventions" title="Conventions">
<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>
<t>Abbreviations used in this document:</t>
<t><list style="empty">
<t>AAA: Authentication, Authorization, Accounting</t>
<t>DNCA: Diameter Network address and port translation Control
Application</t>
<t>NAPT: Network Address and Port Translation</t>
<t>NAT: Network Address Translation (NAT and NAPT are used in this
document interchangeably)</t>
<t>NAT-binding or binding: Association of two IP address/port pairs
(with one IP address typically being private and the other one
public) to facilitate NAT</t>
<t>NAT-device: Network Address Translator or Network Address and
Port Translator: An entity performing NAT or NAPT</t>
<t>NAT-controller: Entity controlling the behavior of a
NAT-device</t>
<t>NAS: Network Access Server</t>
<t>NCR: NAT Control Request</t>
<t>NCA: NAT Control Answer</t>
</list></t>
</section>
<section anchor="framework" title="Deployment Framework">
<section title="Deployment Scenario">
<t><xref target="fig-network-deployment"></xref> shows a typical
network deployment for Internet access. A user’s IPv4 host gains
access to the Internet though a NAS, which facilitates the
authentication of the endpoint and configures the user’s
connection according to the authorization and configuration data
received from the AAA-server upon successful authentication. Public
IPv4 addresses are used throughout the network.</t>
<figure anchor="fig-network-deployment"
title="Typical network deployment for internet access">
<artwork><![CDATA[
+---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+---------+ +---------+ +----------+
| IPv4 | | | | IPv4 |
| Host |----------| NAS |-------------| Internet |
| | | | | |
+---------+ +---------+ +----------+
<-------------------- Public IPv4 ---------------------->
]]></artwork>
</figure>
<t><xref target="fig-NAT-deployment"></xref> depicts the deployment
scenario when a service provider introduces a NAT-device to increase
the efficiency of the global IPv4 address pool utilization. The
objective is to provide the customer with connectivity to the public
IPv4 Internet. The NAT-device performs network address and port (and
optionally address family) translation, depending on whether the
access network uses private IPv4 addresses or public IPv6 addresses,
to public IPv4 addresses. If the NAT-device would be put in place
without any endpoint awareness, the service offerings of the service
provider could be impacted. This includes cases like:</t>
<t><list style="symbols">
<t>Provisioning static NAT bindings for particular endpoints</t>
<t>Using different public IP address pools for different set of
endpoints (for example, residential or business customers)</t>
<t>Reporting allocated bindings on a per endpoint basis</t>
<t>Integrate control of the NAT-device into the already existing
per endpoint management infrastructure of the service provider</t>
</list></t>
<figure anchor="fig-NAT-deployment"
title="Access network deployment with NAT">
<artwork><![CDATA[
+---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+--------+ +---------+ +--------+ +----------+
| IPv4/ | | | | | | IPv4 |
| IPv6 |----| NAS |----| NAT- |----| Internet |
| Host | | | | device | | |
+--------+ +---------+ +--------+ +----------+
<-------- Private IPv4 ----------><--- Public IPv4 --->
<-------- Public IPv6 ----------><--- Public IPv4 --->
]]></artwork>
</figure>
</section>
<section title="Diameter NAPT Control Application Overview">
<t>DNCA runs between two DNCA Diameter peers. One DNCA Diameter peer
resides within the NAT-device, the other DNCA Diameter peer resides
within the NAT-Controller. DNCA allows per endpoint control and
management of NAT within the NAT-device. Based on Diameter, DNCA
integrates well with the suite of Diameter applications deployed for
per endpoint authentication, authorization, accounting, and policy
control in service provider networks.</t>
<t>DNCA offers:<list style="symbols">
<t>Request and answer commands to control the allowed number of
NAT bindings per endpoint , to request the allocation of specific
bindings for an endpoint, to define the address pool to be used
for an endpoint.</t>
<t>Provides per endpoint reporting of the allocated NAT
bindings.</t>
<t>Provides unique identification of an endpoint on NAT-device,
AAA-server and NAS, to simplify correlation of accounting data
streams.</t>
</list></t>
<t>DNCA allows controlling the behavior of a NAT-device on a per
endpoint basis during initial session establishment and at later
stages by providing an update procedure for already established
sessions. Using DNCA, per endpoint NAT binding information can be
retrieved either using accounting mechanisms or through an explicit
session query to the NAT.</t>
</section>
<section title="Deployment Scenarios For DNCA">
<t>DNCA can be deployed in different ways. Two common deployment
scenarios are outlined in <xref
target="fig-NAT-integrated-deployment"></xref> (“integrated
deployment”) and <xref
target="fig-NAT-autonomous-deployment"></xref> (“autonomous
deployment”). The two scenarios differ in which entity fulfills
the role of the NAT-controller. Within the figures (C) denotes the
network element performing the role of the NAT-controller.</t>
<t>The integrated deployment approach hides the existence of the
NAT-device from external servers, such as the AAA-server. It is suited
for environments where minimal changes to the existing AAA deployment
are desired. The NAS and the NAT-device are Diameter peers supporting
the DNCA. The Diameter peer within the NAS, performing the role of the
NAT-controller, initiates and manages sessions with the NAT-device,
exchanges NAT specific configuration information and handles reporting
and accounting information. The NAS receives reporting and accounting
information from NAT-device. With this information, the NAS can
provide a single accounting record for the endpoint. A system
correlating the accounting information received from NAS and
NAT-device would not be needed.</t>
<t>An example network attachment for an integrated NAT deployment can
be described as follows: An endpoint connects to the network, with the
NAS being the point of attachment. After successful authentication,
the NAS receives endpoint related authorization data from the
AAA-server. A portion of the authorization data applies to per
endpoint configuration on the NAS itself, another portion describes
authorization and configuration information for NAT control aimed at
the NAT-device. The NAS initiates a DNCA session to the NAT-device and
sends relevant authorization and configuration information for the
particular endpoint to the NAT-device. This can comprise NAT-bindings,
which have to be pre-established for the endpoint, or management
related configuration, such as the maximum number of NAT-bindings
allowed for the endpoint. The NAT-device sends its per endpoint
accounting information to the NAS, which aggregates the accounting
information received from the NAT-device with its local accounting
information for the endpoint into a single accounting stream towards
the AAA-server.</t>
<figure anchor="fig-NAT-integrated-deployment"
title="NAT control deployment: Integrated deployment">
<artwork><![CDATA[
+---------+
| |
| AAA |
| |
+---------+
|
|
|
+--------+ +---------+ +--------+ +----------+
| IPv4/ | | (C) | | | | IPv4 |
| IPv6 |----| NAS |----| NAT- |----| Internet |
| Host | | | | device | | |
+--------+ +---------+ +--------+ +----------+
<-------- Public IPv6 ----------><--- Public IPv4 --->
<-------- Private IPv4 ----------><--- Public IPv4 --->
]]></artwork>
</figure>
<t>The autonomous deployment approach decouples user management on NAS
and NAT-device. In the autonomous deployment approach, the AAA-system
and the NAT-device are the Diameter peers running the DNCA. The
AAA-system also serves as NAT-controller. It manages the connection to
the NAT-device, controls the per endpoint configuration, and also
receives accounting and reporting information from the NAT-device.
Different from the integrated deployment scenario, the autonomous
deployment scenario does not “hide” the existence of the
NAT-device from the AAA infrastructure. Here two accounting streams
are received by the AAA-server for one particular endpoint, one from
the NAS, and one from the NAT-device.</t>
<figure anchor="fig-NAT-autonomous-deployment"
title="NAT control deployment: Autonomous deployment">
<artwork><![CDATA[
+---------+
| (C) |
| AAA |---------
| | |
+---------+ |
| |
| |
| |
+--------+ +---------+ +---------+ +----------+
| IPv4/ | | | | | | IPv4 |
| IPv6 |----| NAS |----| NAT- |----| Internet |
| Host | | | | device | | |
+--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><---- Public IPv4 --->
<-------- Private IPv4 ----------><---- Public IPv4 --->]]></artwork>
</figure>
</section>
</section>
<section anchor="sec-dnca"
title="DNCA Session Establishment and Management">
<t>Note that this section forward references some of the commands and
AVPs defined for DNCA. Please refer to <xref
target="sec-dnca-commands"></xref> and <xref
target="sec-dnca-avps"></xref> for details. DNCA runs between a Diameter
peer residing in a NAT-controller and a Diameter peer residing in a
NAT-device. The Diameter peer within the NAT-controller is always the
control requesting entity: It initiates, updates, or terminates the
sessions. Sessions are initiated when the NAT-controller learns about a
new endpoint (i.e., host) that requires a NAT service. This could for
example be due to the entity hosting the NAT-controller receiving
authentication, authorization, or accounting requests for or from the
endpoint. Alternate methods that could trigger session set up include
local configuration, receipt of a packet from a formerly unknown
IP-address, etc.</t>
<section title="Session Establishment">
<t>The DNCA Diameter peer within the NAT-controller establishes a
session with the DNCA Diameter peer within the NAT-device to control
the behavior of the NAT function within the NAT-device. During session
establishment, the DNCA Diameter peer within the NAT-controller passes
along configuration information to DNCA Diameter peer within the
NAT-device. The session configuration information comprises the
maximum number of bindings allowed for the endpoint associated with
this session, a set of pre-defined NAT bindings to be established for
this endpoint, or a description of the address pool, that external
addresses are to be allocated from.</t>
<t>The DNCA Diameter peer within the NAT-controller generates a
NAT-Control Request (NCR) message to the DNCA Diameter peer within the
NAT-device with NC-Request-Type AVP set to INITIAL_REQUEST to initiate
a Diameter NAT control session. On receipt of a NCR the DNCA Diameter
peer within the NAT-device sets up a new session for the endpoint
associated with the endpoint classifier(s) contained in the NCR. The
DNCA Diameter peer within the NAT-device notifies its DNCA Diameter
peer within the NAT-controller about successful session setup using a
NAT-Control Answer (NCA) message with Result-Code set to
DIAMETER_SUCCESS. <xref target="fig-session-establishment"></xref>
shows the initial protocol interaction between the two DNCA Diameter
peers.</t>
<t>The initial NAT-Control-Request may contain configuration
information for the session, which specifies the behavior of the
NAT-device for the session. The configuration information which may be
included, comprises: <list style="symbols">
<t>A list of NAT bindings, which should be pre-allocated for the
session; for example, in case a user requires a fixed external
IP-address/port pair for one of his applications.</t>
<t>The maximum number of NAT-bindings allowed for an endpoint.</t>
<t>A description of the external IP-address pool(s) to be used for
the session.</t>
<t>A reference to a predefined binding rule on the NAT-device,
which is applied to the session. Such a predefined binding rule on
the NAT-device may contain, for example, the name of the
IP-address pool that external IP-addresses should be allocated
from, the maximum number of bindings permitted for the endpoint,
etc.</t>
</list></t>
<t>In certain cases, the NAT-device may not be able to perform the
tasks requested within the NCR. These include the following: <list
style="symbols">
<t>If a DNCA Diameter peer within the NAT-device receives a NCR
from a DNCA Diameter peer within a NAT-controller with NC-
Request-Type AVP set to INITIAL_REQUEST that identifies an already
existing session; that is, DNCA Diameter peer and endpoint
identifier match an already existing session, the DNCA Diameter
peer within the NAT-device returns NCA with Result-Code set to
SESSION_EXISTS, and provides the Session-Id of the existing
session in the Duplicate-Session-Id AVP.</t>
<t>If a DNCA Diameter peer within the NAT-device receives a NCR
from a DNCA Diameter peer within a NAT-controller with NC-
Request-Type AVP set to INITIAL_REQUEST that matches more than one
of the already existing sessions; that is, DNCA Diameter peer and
endpoint identifier match already existing sessions, the DNCA
Diameter peer within the NAT-device returns a NCA with Result-Code
set to INSUFFICIENT-CLASSIFIERS. In case a DNCA Diameter peer
receives a NCA that reports Insufficient-Classifiers, it may
choose to retry establishing a new session using additional or
more specific classifiers.</t>
<t>If the NCR contains a binding rule not defined on the
NAT-device, the DNCA Diameter peer within the NAT-device returns
NCA with Result-Code AVP set to UNKNOWN_BINDING_RULE.</t>
<t>In case the NAT-device is unable to establish all of the
bindings requested in the NCR, the DNCA Diameter peer will return
a NCA with Result-Code set to BINDING_FAILURE. A DNCA Diameter
peer within a NAT-device treats a NCR as an atomic operation;
hence none of the requested bindings will be established by the
NAT-device. Either all requested actions within a NCR are
completed successfully, or the entire request fails.</t>
<t>If a NAT-device does not have sufficient resources to process a
request, the DNCA Diameter peer returns a NCA with Result-Code set
to RESOURCE_FAILURE.</t>
<t>In case Max-NAT-Binding and NAT-Control-Definition are included
in the NCR along with a reference to a binding rule; that is, a
predefined template on NAT-device, and the values in
Max-NAT-Binding and NAT-Control-Definition contradict those
specified in the pre-defined binding rule, Max-NAT-Binding and
NAT-Control-Definition override the values specified in the
binding rule.</t>
</list></t>
<figure anchor="fig-session-establishment"
title="Initial NAT control request and session establishment ">
<artwork><![CDATA[
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| |
| |
| |
Trigger |
| |
| NCR |
|------------------------------------------>|
| (INITIAL_REQUEST, endpoint classifier, |
| session id, NAT control config data) |
| |
| |
| |
| |
| If Able to comply
| with Request then
| Create session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |]]></artwork>
</figure>
<t>Note: The DNCA Diameter peer within the NAT-device creates session
state only if it is able to comply with the NCR. On success it will
reply with a NCA with Result-Code set to DIAMETER_SUCCESS.</t>
</section>
<section title="Session Re-Authorization">
<t>Session re-authorization is performed if the NAT-controller desires
to change the behavior of the NAT-device for an existing session.
Session re-authorization could be used, for example, to change the
number of allowed bindings for a particular session, or establish or
remove a pre-defined binding.</t>
<t>The DNCA Diameter peer within the NAT-controller generates a NCR
message to DNCA Diameter peer within NAT-device with NC-Request-Type
AVP set to UPDATE_REQUEST upon receiving a trigger signal. If the
session is updated successfully, the DNCA Diameter peer within the
NAT-device notifies the DNCA Diameter peer within the NAT-controller
about the successful session update using a NAT-Control Answer (NCA)
message with Result-Code set to DIAMETER_SUCCESS. <xref
target="fig-session-re-auth"></xref> shows the protocol interaction
between the two DNCA Diameter peers.</t>
<t>In certain cases, the NAT-device may not be able to perform the
tasks requested within the NCR. These include the following: <list
style="symbols">
<t>If DNCA Diameter peer within a NAT-device receives a NCR update
or query request for a non-existent session, it sets Result-Code
in the answer to DIAMETER_UNKNOWN_SESSION_ID.</t>
<t>If the NCR contains a binding rule not defined on the
NAT-device, a NCA with Result-Code AVP set to UNKNOWN_BINDING_RULE
is returned.</t>
<t>If the NAT-device cannot establish the requested binding
because the maximum number of allowed bindings has been reached
for the endpoint classifier, a NCA with Result-Code AVP set to
MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT by the DNCA Diameter
peer.</t>
<t>If the NAT-device cannot establish some or all of the bindings
requested in a NCR, but has not yet reached the maximum number of
allowed bindings for the endpoint, a NCA with Result-Code set to
BINDING_FAILURE is returned. As already noted, the DNCA Diameter
peer in a NAT-device treats a NCR as an atomic operation. Hence
none of the requested bindings will be established by the
NAT-device in case of failure. Actions requested within a NCR are
either all successful or all fail.</t>
<t>If the NAT-device does not have sufficient resources to process
a request, a NCA with Result-Code set to RESOURCE_FAILURE is
returned.</t>
<t>If a NCR redefines the maximum number of NAT-bindings allowed
for the endpoint, the new value will override any previously
defined limit on NAT bindings. It depends on the implementation of
the NAT-device on how the NAT-device copes with a case where the
new value is lower than the actual number of allocated bindings.
Typically the NAT-device refrains from enforcing the new limit
immediately; that is, actively remove bindings, but rather
disallow the establishment of new bindings until the current
number of bindings is lower than the newly established maximum
number of allowed bindings.</t>
<t>If a NCR specifies a new binding rule, predefined on the
NAT-device, the binding rule overrides any previously defined rule
for the session.</t>
<t>If Max-NAT-Binding and NAT-Control-Definition AVPs are included
in the NCR along with a reference to a binding rule (a predefined
template on the NAT-device) and the values in Max-NAT-Binding and
NAT-Control-Definition AVPs contradict those specified in the
pre-defined binding rule, Max-NAT-Binding and
NAT-Control-Definition AVPs override the values specified in the
binding rule.</t>
</list>Note: Already established bindings for the session will not
be affected in case the tasks requested within the NCR cannot be
completed.</t>
<figure anchor="fig-session-re-auth"
title="NAT control request for session update ">
<artwork><![CDATA[
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| |
| |
| |
Change of session |
attributes |
| |
| NCR |
|------------------------------------------>|
| (UPDATE_REQUEST session id, |
| NAT control config data) |
| |
| |
| If able to comply
| with the request:
| Update session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |]]></artwork>
</figure>
</section>
<section title="Session and Binding Query">
<t>Session query can be used by the DNCA Diameter peer within the
NAT-controller to either retrieve information on the current bindings
for a particular session at the NAT-device or discover the session
identifier for a particular external IP address/port pair.</t>
<t>A DNCA Diameter peer within the NAT-controller starts a session
query by sending a NCR message with NC-Request-Type AVP set to
QUERY_REQUEST. <xref target="fig-session-query"></xref> shows the
protocol interaction between the DNCA Diameter peers.</t>
<t>Two types of query requests exist. The first type of query request
uses the session ID as input parameter to the query. It is to allow
the DNCA Diameter peer within the NAT-controller to retrieve the
current set of bindings for a specific session. The second type of
query request is used to retrieve the session identifiers, along with
the associated bindings, matching a criteria. This enables the DNCA
Diameter peer within the NAT-controller to find those sessions, which
utilize a specific external IP-address.</t>
<t><list style="numbers">
<t>Request a list of currently allocated NAT bindings for a
particular session: On receiving a NCR, the NAT-device looks up
the session information for the session ID contained in the NCR,
and reports all currently active NAT-bindings for the session
using a NCA message with Result-Code set to DIAMETER_SUCCESS. In
this case the NCR MUST NOT contain a NAT-Control-Definition AVP.
Each NAT-binding is reported in a NAT-Control-Definition AVP. In
case the session ID is unknown, the DNCA Diameter peer within the
NAT-device returns NCA with Result-Code set to
DIAMETER_UNKNOWN_SESSION_ID.</t>
<t>Retrieve session IDs and internal IP address/port pairs for one
or multiple external IP-address/port pairs: If the DNCA Diameter
peer within the NAT-controller wishes to retrieve the session
ID(s) for one or multiple external IP-address/port pairs, it MUST
include the external IP-address/port pair(s) as part of the
NAT-Control-Definition AVP of the NCR. The session ID is not
included in the NCR or the NCA for this type of a query. The DNCA
Diameter peer within the NAT-device reports the NAT-bindings and
associated session IDs corresponding to the external
IP-address/port pairs in a NCA message with Result-Code set to
DIAMETER_SUCCESS with the same session ID, which was used in NCR.
In case an external IP-address/port pair has no associated
existing NAT-binding, the NAT-Control-Definition AVP contained in
the reply just contains the NAT-External-Address AVP.</t>
</list></t>
<figure anchor="fig-session-query" title="Session query">
<artwork><![CDATA[
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| |
| |
| |
DNCA Session Established |
| |
| NCR |
|------------------------------------------>|
| (QUERY_REQUEST) |
| |
| |
| |
| Look up corresponding session
| and associated NAT-bindings
| |
| NCA |
|<------------------------------------------|
| (Result-Code) |
| |
| |]]></artwork>
</figure>
</section>
<section anchor="sec-dnca-sess-term" title="Session Termination">
<t>Similar to session initiation, session tear down is always
initiated by the DNCA Diameter peer within the NAT-controller. The
DNCA Diameter peer sends a Session Terminate Request (STR) message to
its peer within the NAT-device upon receiving a trigger signal. The
source of the trigger signal is outside the scope of this document. In
response, the DNCA Diameter peer within the NAT-device sends an
accounting stop record reporting all bindings and notifies its DNCA
Diameter peer about successful session termination using a Session
Terminate Answer (STA) message with Result-Code set to
DIAMETER_SUCCESS. <xref target="fig-session-terminate"></xref> shows
the protocol interaction between the two DNCA Diameter peers.</t>
<t>If a DNCA Diameter peer within a NAT-device receives a STR and
fails to find a matching session, the DNCA Diameter peer returns a STA
with Result-Code set to DIAMETER_UNKNOWN_SESSION_ID.</t>
<figure anchor="fig-session-terminate"
title="Terminate NAT control session">
<artwork><![CDATA[
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| |
| |
Trigger |
| |
| STR |
|------------------------------------------->|
| (session id) |
| |
| |
| Remove NAT-bindings
| of session
| |
| |
| Send accounting stop |
|<-------------------------------------------|
| reporting all session bindings |
| |
| Terminate session /
| Remove session state
| |
| |
| |
| STA |
|<-------------------------------------------|
| (Result-Code) |
| |]]></artwork>
</figure>
</section>
<section title="Session Abort">
<t>An Abort-Session-Request (ASR) message is sent from the DNCA
Diameter peer within the NAT-device to the DNCA Diameter peer within
the NAT-controller when it is unable to maintain a session due to
resource limitations. The DNCA Diameter peer within the NAT-controller
acknowledges successful session abort using a Abort Session Answer
(ASA) message with Result-Code set to DIAMETER_SUCCESS. <xref
target="fig-session-abort"></xref> shows the protocol interaction
between the DNCA Diameter peers. The DNCA Diameter peers will start a
session termination procedure as described in <xref
target="sec-dnca-sess-term"></xref> following an ASA with Result-Code
set to DIAMETER_SUCCESS.</t>
<t>If the DNCA Diameter peer within a NAT-controller receives an ASR
but fails to find a matching session, it returns an ASA with
Result-Code set to DIAMETER_UNKNOWN_SESSION_ID. If the DNCA Diameter
peer within the NAT-controller is unable to comply with the ASR for
any other reason, an ASA with Result-Code set to
DIAMETER_UNABLE_TO_COMPLY is returned.</t>
<figure anchor="fig-session-abort" title="Abort NAT control session">
<artwork><![CDATA[
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| |
| |
| Trigger
| |
| ASR |
|<-------------------------------------------|
| (session id) |
| |
| |
| ASA |
|------------------------------------------->|
| (Result-Code) |
| |
| |
| On successful ASA |
|<------Session Termination Procedure------->|]]></artwork>
</figure>
</section>
<section title="Failure cases of the DNCA Diameter peers">
<t>This document does not specify the behavior in case NAT-device and
NAT-controller, or their respective DNCA Diameter peers are out of
sync. This could happen for example if one of the entities restarts,
in case of a (temporary) loss of network connectivity etc. The peering
entities MUST have built-in redundancy support to recover state in
case of failure.</t>
<t>Example failure cases include the following:</t>
<t><list style="symbols">
<t>NAT-controller and the DNCA Diameter peer within the
NAT-controller lose state (e.g. due to a restart). In this case,
<list style="symbols">
<t>the DNCA Diameter peer within the NAT-device may receive a
NCR with NC-Request-Type AVP set to INITIAL_REQUEST that
matches an existing session of the DNCA Diameter peer within
the NAT-device. The DNCA Diameter peer within the NAT-device
returns a Result-Code that contains Duplicate-Session-Id AVP
to report the Session-ID of the existing session. The DNCA
Diameter peer within the NAT-controller may send an explicit
Session Terminate Request (STR) for the older session, which
was lost.</t>
<t>a DNCA Diameter peer may receive accounting records for a
session that does not exist. The DNCA Diameter peer sends an
accounting answer with Result-Code set to
DIAMETER_UNKNOWN_SESSION_ID in response. On receiving the
response, the DNCA Diameter peer clears the session and
removes the associated session state.</t>
</list></t>
<t>NAT-device and the DNCA Diameter peer within NAT-device lose
state. In such a case, the DNCA Diameter peer may receive a NCR
with NC-Request-Type AVP set to UPDATE_REQUEST for a non-existent
session. The DNCA Diameter peer returns NCA with Result-Code set
to DIAMETER_UNKNOWN_SESSION_ID.</t>
<t>The DNCA Diameter peer within the NAT-controller is
unreachable, for example detected by Diameter watchdog, or down
and accounting requests from the DNCA Diameter peer fail to get a
response. The mechanism to ensure that a DNCA Diameter peer within
the NAT-controller no longer has associated state for a session
which was cleared or removed by the DNCA Diameter peer within the
NAT-device is beyond the scope of this document.</t>
<t>The DNCA Diameter peer within the NAT-device is unreachable or
down and NCR requests fail to get a response. Handling of this
case depends on the actual service offering of the service
provider. The service provider could for example choose to stop
offering connectivity service.</t>
</list></t>
</section>
</section>
<section anchor="sec-diameter-base-use"
title="Use Of The Diameter Base Protocol">
<t>The Diameter Base Protocol defined by <xref target="RFC3588"></xref>
applies with the clarifications listed in the present specification.</t>
<section anchor="sec-diameter-messages"
title="Securing Diameter Messages ">
<t>For secure transport of Diameter messages recommendations in <xref
target="RFC3588"></xref> apply.</t>
<t>DNCA Diameter peers MAY verify their identity during the
Capabilities Exchange Request procedure.</t>
<t>A DNCA Diameter peer within the NAT-device MAY verify that a DNCA
Diameter peer that issues a NCR command is allowed to do so based on:
<list style="symbols">
<t>The identity of the DNCA Diameter peer</t>
<t>The type of NCR Command</t>
<t>The content of the NCR Command</t>
<t>Any combination of the above</t>
</list></t>
</section>
<section title="Accounting Functionality">
<t>Accounting functionality (accounting session state machine, related
command codes and AVPs) is defined in <xref
target="sec-accounting"></xref> below.</t>
</section>
<section title="Use Of Sessions">
<t>Each DNCA session MUST have a globally unique Session-ID as defined
in <xref target="RFC3588"></xref>, which MUST NOT be changed during
the lifetime of a DNCA session. The Diameter Session-ID serves as the
global endpoint identifier. The DNCA Diameter peers maintain state
associated with the Session-ID. This globally unique Session-ID is
used for updating, accounting, and terminating the session. DNCA
session MUST NOT have more than one outstanding request at any given
instant. A DNCA Diameter peer sends an Abort-Session-Request as
defined in <xref target="RFC3588"></xref> if it is unable to maintain
sessions due to resource limitation.</t>
</section>
<section title="Routing Considerations">
<t>It is assumed that the DNCA Diameter peer within a NAT-controller
knows the DiameterIdentity of the Diameter peer within a NAT-device
for a given endpoint. Both the Destination-Realm and Destination-Host
AVPs are present in the request from a DNCA Diameter peer within a
NAT-controller to a DNCA Diameter peer within a NAT-device.</t>
</section>
<section title="Advertising Application Support">
<t>Diameter nodes conforming to this specification MUST advertise
support for DNCA by including the value of TBD in the
Auth-Application-Id of the Capabilities-Exchange-Request and
Capabilities-Exchange-Answer command<xref
target="RFC3588"></xref>.</t>
</section>
</section>
<section anchor="sec-dnca-commands" title="DNCA Commands">
<t>The following commands are used to establish, maintain and query
NAT-bindings.</t>
<section anchor="sec-dnca-ncr" title="NAT-Control Request (NCR) Command">
<t>The NAT-Control Request (NCR) command, indicated by the command
field set to TBD and the "R" bit set in the Command Flags field, is
sent from the DNCA Diameter peer within the NAT-controller to the DNCA
Diameter peer within the NAT-device in order to install
NAT-bindings.</t>
<t>User-Name, Logical-Access-Id, Physical-Access-ID,
Framed-IP-Address, Framed-IPv6-Prefix , Framed-Interface-Id,
EGRESS-VLANID, NAS-Port-ID, Address-Realm, Calling-Station-ID AVPs
serve as identifiers for the endpoint.</t>
<t>Message format:</t>
<figure>
<artwork><![CDATA[ < NC-Request > ::= < Diameter Header: TBD, REQ, PXY>
[ Session-Id ]
{ Auth-Application-Id }
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Destination-Host }
{ NC-Request-Type }
[ Origin-State-Id ]
*1 [ NAT-Control-Remove ]
*1 [ NAT-Control-Install ]
[ User-Name ]
[ Logical-Access-Id ]
[ Physical-Access-ID ]
[ Framed-IP-Address ]
[ Framed-IPv6-Prefix ]
[ Framed-Interface-Id ]
[ EGRESS-VLANID]
[ NAS-Port-ID]
[ Address-Realm ]
[ Calling-Station-ID ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ AVP ]
]]></artwork>
</figure>
</section>
<section anchor="sec-dnca-nca" title="NAT-Control Answer (NCA) Command">
<t>The NAT-Control-Answer (NCA) command, indicated by the Command-Code
field set to TBD and the "R" bit cleared in the Command Flags field,
is sent by the DNCA Diameter peer within the NAT-device in response to
NAT-Control-Request command.</t>
<t>Message format:</t>
<figure>
<artwork><![CDATA[ <NC-Answer> ::= < Diameter Header: TBD, PXY >
[ Session-Id ]
{ Origin-Host }
{ Origin-Realm }
{ Result-Code }
[ NC-Request-Type ]
* [ NAT-Control-Definition ]
[ Current-NAT-Bindings ]
[ Origin-State-Id ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
* [ Proxy-Info ]
[ Duplicate-Session-ID ]
* [ Redirect-Host]
[ Redirect-Host-Usage ]
[ Redirect-Max-Cache-Time ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ Failed-AVP ]
* [ AVP ]
]]></artwork>
</figure>
</section>
</section>
<section title="NAT Control Application Session State Machine">
<t>This section contains a set of finite state machines, representing
the life cycle of DNCA session, which MUST be observed by all
implementations of the DNCA Diameter application. The DNCA Diameter
peers are stateful and the state machine maintained is similar to the
stateful Client and Server authorization state machine described in
<xref target="RFC3588"></xref>. When a session is moved to the Idle
state, any resources that were allocated for the particular session must
be released. Any event not listed in the state machines MUST be
considered as an error condition, and an answer, if applicable, MUST be
returned to the originator of the message.</t>
<t>In the state table, the event 'Failure to send NCR' means that the
DNCA Diameter peer within the NAT-controller is unable to send the NCR
command to the desired destination. This could be due to the peer being
down, or due to the peer sending back the transient failure or temporary
protocol error notification DIAMETER_TOO_BUSY or DIAMETER_LOOP_DETECTED
in the Result-Code AVP of NCA.</t>
<t>In the state table "FAILED NCA" means that the DNCA Diameter peer
within the NAT-device was not able to honor the corresponding NCR. This
can happen due to any transient and permanent error at the NAT-device or
its associated DNCA Diameter peer within indicated by the following
error Result-Code values: RESOURCE_FAILURE, UNKNOWN_BINDING_RULE_NAME,
BINDING_FAILURE, MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT, SESSION_EXISTS,
INSUFFICIENT_CLASSIFIERS.</t>
<t>The following state machine is observed by a DNCA Diameter peer
within a NAT-controller. The state machine description uses the term
"access session" to describe the connectivity service offered to the
endpoint or host. "Access session" should not be confused with the
Diameter session ID.</t>
<figure>
<artwork><![CDATA[
DNCA Diameter peer within a NAT-controller
State Event Action New State
-------------------------------------------------------------
Idle New endpoint detected that Send Pending
requires NAT Control NCR
Initial
Request
Idle ASR Received Send ASA Idle
for unknown session with
Result-Code
= UNKNOWN_
SESSION_ID
Pending Successful NCA Setup Open
received complete
Pending Successful NCA Sent STR Discon
received
but peer unable to provide
service
Pending Error processing successful Sent STR Discon
NCA
Pending Failed Cleanup Idle
NCA received
Open NAT control Send Open
update required NCR Update
Request
Open Successful Open
NCA received
Open Failed Cleanup Idle
NCA received.
Open Access session end detected Send STR Discon
Open ASR Received, Send ASA Discon
access session will be with
terminated Result-Code
= SUCCESS,
Send STR.
Open ASR Received, Send ASA Open
access session will not with
be terminated Result-Code
!= SUCCESS
Discon ASR Received Send ASA Idle
Discon STA Received Discon. Idle
user/device]]></artwork>
</figure>
<t>The following state machine is observed by a DNCA Diameter peer
within a NAT-device.</t>
<figure>
<artwork><![CDATA[
DNCA Diameter peer within a NAT-device
State Event Action New State
-------------------------------------------------------------
Idle NCR request Send Open
received, and successful
able to provide requested NCA
NAT control service
Idle NCR request Send Idle
received, and failed
unable to provide requested NCA
NAT control service
Open NCR request Send Open
received, and successful
able to provide requested NCA
NAT control service
Open NCR request Send Idle
received, and failed
unable to provide requested NCA,
NAT control service Cleanup
Open Unable to continue Send ASR Discon
providing requested
NAT control service
Discon Failure to send ASR Wait, Discon
resend ASR
Discon ASR successfully sent and Cleanup Idle
ASA Received with Result-Code
Not ASA Received None No change
Discon
Any STR Received Send STA, Idle
Cleanup.]]></artwork>
</figure>
</section>
<section anchor="sec-dnca-avps" title="DNCA AVPs">
<t></t>
<section title="Reused Base Protocol AVPs">
<t>AVPs reused from Diameter Base Protocol <xref
target="RFC3588"></xref> are listed below.</t>
<figure anchor="tab-avps-from-diameter-base"
title="DIAMETER AVPs used from Diameter base ">
<artwork><![CDATA[ +-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP | | | May |
| Attribute Name Code Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|Acct-Interim-Interval 85 Unsigned32 | M | P | Y |
|Auth-Application-Id 258 Unsigned32 | M | P | N |
|Destination-Host 293 DiamIdent | M | P | N |
|Destination-Realm 283 DiamIdent | M | P | N |
|Error-Message 281 UTF8String | M | P | N |
|Error-Reporting-Host 294 DiamIdent | M | P | N |
|Failed-AVP 279 Grouped | M | P | N |
|Origin-Host 264 DiamIdent | M | P | N |
|Origin-Realm 296 DiamIdent | M | P | N |
|Origin-State-Id 278 Unsigned32 | M | P | N |
|Proxy-Info 284 Grouped | M | P | N |
|Result-Code 268 Unsigned32 | M | P | N |
|Route-Record 282 DiamIdent | M | | N |
|Session-Id 263 UTF8String | M | P | Y |
|User-Name 1 UTF8String | M | P | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
+-------------------------------------------------------------------+
]]></artwork>
</figure>
<t>The Auth-Application-Id AVP (AVP Code 258) is assigned by IANA to
Diameter applications. The value of the Auth-Application-Id for the
Diameter NAT Control Application is TBD.</t>
</section>
<section anchor="sec_result-codes"
title="Additional Result-Code AVP Values">
<t>This section defines new values for the Result-Code AVP which SHALL
be supported by all Diameter implementations that conform to the
present document.</t>
<section title="Success">
<t>No new Result-Code AVP value is defined within this category.</t>
</section>
<section anchor="sec_result-code-transient" title="Transient Failures">
<t>Result-Code AVP values that fall within the transient failures
category are those used to inform a peer that the request could not
be satisfied at the time that it was received. The request may be
able to be satisfied in the future.</t>
<t>The following new values of the Result-Code AVP are defined:</t>
<t><list style="empty">
<t>RESOURCE_FAILURE (TBD)<list style="empty">
<t>The DNCA Diameter peer within the NAT-device indicates
that the binding could not be installed or a new session
could not be created due to resource shortage.</t>
</list></t>
</list></t>
</section>
<section anchor="sec_result-code-permanent"
title="Permanent Failures ">
<t>The Result-Code AVP values, which fall within the permanent
failures category are used to inform the peer that the request
failed, and should not be attempted again. The request may be able
to be satisfied in the future.</t>
<t>The following new values of the Result-Code AVP are defined:</t>
<t><list style="empty">
<t>UNKNOWN_BINDING_RULE_NAME (TBD)<list style="empty">
<t>The DNCA Diameter peer within the NAT-device indicates
that the binding could not be installed or a new session
could not be created because the specified
NAT-Control-Binding-Rule AVP, that refers to a predefined
policy template in the NAT-device, is unknown.</t>
</list>BINDING_FAILURE (TBD)<list style="empty">
<t>DNCA indicates that the requested binding(s) could not be
installed. For example: Requested ports are already in
use.</t>
</list></t>
<t>MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT (TBD)<list
style="empty">
<t>The DNCA Diameter peer within the NAT-device denies the
request because the maximum number of allowed bindings has
been reached for the specified endpoint classifier.</t>
</list></t>
<t>SESSION_EXISTS (TBD)<list style="empty">
<t>The DNCA Diameter peer within the NAT-device denies
request to initialize a new session, if it already has a
DNCA session that uses the same set of classifiers as
indicated by the DNCA Diameter peer within the
NAT-controller in the new session initialization
request.</t>
</list></t>
<t>INSUFFICIENT_CLASSIFIERS (TBD)<list style="empty">
<t>The DNCA Diameter peer within the NAT-device requests to
initialize a new session, if the classifiers in the request
match more than one of the existing sessions on the DNCA
Diameter peer within the NAT-device.</t>
</list></t>
</list></t>
</section>
</section>
<section title="Reused NASREQ Diameter Application AVPs">
<t>The following AVPs are reused from Diameter Network Access Server
Application <xref target="RFC4005"></xref>.</t>
<figure anchor="tab-avps-from-nasreq"
title="Reused NASREQ Diameter application AVPs">
<artwork><![CDATA[ +---------------------+
| AVP Flag rules |
+------------------+------+------------|----+-----+----+-----|----+
| | AVP | | | |SHLD| MUST| |
| Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr|
|------------------|------|------------|----+-----+----+-----|----|
| NAS-Port | 5 | Unsigned32 | M | P | | V | Y |
| NAS-Port-Id | 87 | UTF8String | M | P | | V | Y |
| Calling-Station- | 31 | UTF8String | M | P | | V | Y |
| Id | | | | | | | |
| Framed-IP-Address| 8 | OctetString| M | P | | V | Y |
| Framed-Interface-| 96 | Unsigned64 | M | P | | V | Y |
| Id | | | | | | | |
| Framed-IPv6- | 97 | OctetString| M | P | | V | Y |
| Prefix | | | | | | | |
+------------------+------+------------|----+-----+----+-----|----+]]></artwork>
</figure>
</section>
<section title="Reused AVPs from RFC 4675 ">
<t>The following AVPs are reused from "RADIUS Attributes for Virtual
LAN and Priority Support" specification <xref
target="RFC4675"></xref>.</t>
<figure anchor="tab-avps-from-rfc4675"
title="Reused attributes from RFC 4675">
<artwork><![CDATA[ +---------------------+
| AVP Flag rules |
+------------------+------+------------|----+-----+----+-----|----+
| | AVP | | | |SHLD| MUST| |
| Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr|
|------------------|------|------------|----+-----+----+-----|----|
| Egress-VLANID | 56 | OctetString| M | P | | V | Y |
+------------------+------+------------|----+-----+----+-----|----+]]></artwork>
</figure>
</section>
<section title="Reused AVPs from Diameter QoS Application">
<t>The following AVPs are reused from the Traffic Classification and
Quality of Service (QoS) Attributes for Diameter <xref
target="RFC5777"></xref>.</t>
<figure anchor="tab-avps-from-diameter-qos"
title="Reused QoS-attributes">
<artwork><![CDATA[ +-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP | | | May |
| Attribute Name Code Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|Port TBD Integer32 | M | P | Y |
|IP-Address-Mask TBD Grouped | M | P | Y |
|Protocol TBD Enumerated | M | P | Y |
|Direction TBD Enumerated | M | P | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
+-------------------------------------------------------------------+]]></artwork>
</figure>
</section>
<section title="Reused AVPs from ETSI ES 283 034, e4 Diameter Application">
<t>The following AVPs are reused from the Diameter e4 Application
<xref target="ETSIES283034"></xref>.</t>
<figure anchor="tab-avps-from-diameter-e4"
title="Reused AVPs from Diameter e4 application ">
<artwork><![CDATA[ +-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP | | | May |
| Attribute Name Code Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|Address-Realm 301 OctetString | M,V | | Y |
|Logical-Access-Id 302 OctetString | V | M | Y |
|Physical-Access-ID 313 UTF8String | V | M | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
|V - Indicates whether the optional Vendor-ID field is present |
| in the AVP header. Vendor-Id header of all AVPs in |
| this table will be set to ETSI (13019). |
+-------------------------------------------------------------------+]]></artwork>
</figure>
</section>
<section title="DNCA Defined AVPs">
<t>The following table describes the new Diameter AVPs used in this
document.</t>
<figure anchor="tab-new-avps" title="New Diameter AVPs">
<artwork><![CDATA[ +-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP Section | | | May |
| Attribute Name Code Defined Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|NC-Request-Type TBD 8.7.1 Enumerated | M | P | Y |
|NAT-Control-Install TBD 8.7.2 Grouped | M | P | Y |
|NAT-Control-Remove TBD 8.7.3 Grouped | M | P | Y |
|NAT-Control-Definition TBD 8.7.4 Grouped | M | P | Y |
|NAT-Internal-Address TBD 8.7.5 Grouped | M | P | Y |
|NAT-External-Address TBD 8.7.6 Grouped | M | P | Y |
|Max-NAT-Bindings TBD 8.7.7 Unsigned32 | M | P | Y |
|NAT-Control- TBD 8.7.8 OctetString| M | P | Y |
| Binding-Rule | | | |
|Duplicate- TBD 8.7.9 UTF8String | M | P | Y |
| Session-ID | | | |
|NAT-Control-Record TBD 9.2.1 Grouped | M | P | Y |
|NAT-Control- TBD 9.2.2 Enumerated | M | P | Y |
| Binding-Status | | | |
|Current-NAT-Bindings TBD 9.2.3 Unsigned32 | M | P | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
+-------------------------------------------------------------------+]]></artwork>
</figure>
<section anchor="avp_NC-Request-Type" title="NC-Request-Type AVP">
<t>The NC-Request-Type AVP (AVP Code TBD) is of type Enumerated and
contains the reason for sending the NAT-Control-Request command. It
shall be present in all NAT-Control-Request messages.</t>
<t>The following values are defined: <list style="empty">
<t>INITIAL_REQUEST (1)<list style="empty">
<t>An Initial Request is to initiate a Diameter NAT control
session between the DNCA Diameter peers.</t>
</list>UPDATE_REQUEST (2)<list style="empty">
<t>An Update Request is used to update bindings previously
installed on a given access session, to add new binding on a
given access session, or to remove one or several binding(s)
activated on a given access session.</t>
</list></t>
<t>QUERY_REQUEST (3)<list style="empty">
<t>Query Request is used to query a NAT-device about the
currently installed bindings for an endpoint classifier.</t>
</list></t>
</list></t>
</section>
<section anchor="avp_NAT-Control-Install"
title="NAT-Control-Install AVP">
<t>The NAT-Control AVP (AVP code TBD) is of type Grouped, and it is
used to activate or install NAT bindings. It also contains
Max-NAT-Bindings that defines the maximum number of NAT bindings to
be allowed for a subscriber and the NAT-Control-Binding-Rule that
references a predefined policy template on the NAT-device that may
contain static binding, a maximum number of bindings allowed, an
IP-address pool from which external binding addresses should be
allocated.</t>
<t>AVP format:</t>
<figure>
<artwork><![CDATA[ NAT-Control-Install ::= < AVP Header: TBD >
* [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ]
[ Max-NAT-Bindings]
* [ AVP ]]]></artwork>
</figure>
</section>
<section anchor="avp_NAT-Control-Remove"
title="NAT-Control-Remove AVP">
<t>The NAT-Control-Remove AVP (AVP code TBD) is of type Grouped, and
it is used to deactivate or remove NAT-bindings.</t>
<t>AVP format:</t>
<figure>
<artwork><![CDATA[ NAT-Control-Remove ::= < AVP Header: TBD >
* [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ]
* [ AVP ]]]></artwork>
</figure>
</section>
<section anchor="avp_NAT-Control-Definition"
title="NAT-Control-Definition AVP">
<t>The NAT-Control-Definition AVP (AVP code TBD) is of type Grouped,
and it describes a binding.</t>
<t>The NAT-Control-Definition AVP uniquely identifies the binding
between the DNCA Diameter peers.</t>
<t>If both the NAT-Internal-Address and NAT-External-Address AVP(s)
are supplied, it is a pre-defined binding.</t>
<t>The Protocol AVP describes the transport protocol for the
binding. The NAT-Control-Definition AVP can contain either zero or
one Protocol AVP. If the Protocol AVP is omitted and if both
internal and external IP-address are specified then the binding
reserves the IP-addresses for all transport protocols.</t>
<t>The Direction AVP is of type Enumerated. It specifies the
direction for the binding. The values of the enumeration applicable
in this context are: "IN","OUT". If Direction AVP is OUT or absent,
the NAT-Internal-Address refers to the IP-address of the endpoint
that needs to be translated. If Direction AVP is "IN",
NAT-Internal-Address is the destination IP-address that has to be
translated.</t>
<t>AVP format:</t>
<figure>
<artwork><![CDATA[ NAT-Control-Definition ::= < AVP Header: TBD >
{ NAT-Internal-Address }
[ Protocol ]
[ Direction ]
[ NAT-External-Address ]
[ Session-Id ]
* [ AVP ]]]></artwork>
</figure>
</section>
<section anchor="avp_NAT-Internal-Address"
title="NAT-Internal-Address AVP">
<t>The NAT-Internal-Address AVP (AVP code TBD) is of type Grouped.
It describes the internal IP-address and port for a binding.
Framed-IPV6-Prefix and Framed-IP-Address AVPs are mutually
exclusive.</t>
<t>AVP format:</t>
<figure>
<artwork><![CDATA[ NAT-Internal-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ]
[ Framed-IPv6-Prefix ]
[ Port]
* [ AVP ]]]></artwork>
</figure>
</section>
<section anchor="avp_NAT-External-Address"
title="NAT-External-Address AVP">
<t>The NAT-External-Address AVP (AVP code TBD) is of type Grouped,
and it describes the external IP-address and port for a binding.
IP-Address-Mask AVP can only be specified when the Framed-IP-Address
AVP is present. The external IP-address specified in this attribute
can be reused for multiple endpoints by specifying the same address
in the respective NAT-External-Address AVPs.</t>
<t>AVP format:</t>
<figure>
<artwork><![CDATA[ NAT-External-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ]
[ IP-Address-Mask ]
[ Port ]
* [ AVP ]]]></artwork>
</figure>
</section>
<section anchor="avp_Max-NAT-Bindings" title="Max-NAT-Bindings">
<t>The Max-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32. It
indicates the maximum number of NAT-bindings allowed for a
particular endpoint.</t>
</section>
<section anchor="avp_NAT-Control-Binding-Rule"
title="NAT-Control-Binding-Rule AVP">
<t>The NAT-Control-Binding-Rule AVP (AVP code TBD) is of type
OctetString. It defines a name for a policy template that is
predefined at the NAT-device. Details on the contents and structure
of the template and configuration are outside the scope of this
document. The policy to which this AVP refers to may contain
NAT-bindings, IP-address pool for allocating the external IP-address
of a NAT-binding, and maximum number of allowed NAT-bindings. Such
policy template can be reused by specifying the same
NAT-Control-Binding-Rule AVP in the corresponding
NAT-Control-Install AVPs of multiple endpoints.</t>
</section>
<section anchor="avp_Duplicate-Session-Id"
title="Duplicate-Session-Id AVP">
<t>The Duplicate-Session-Id AVP (AVP Code TBD) is of type
UTF8String. It is used to report errors and contains the Session-Id
of an existing session.</t>
</section>
</section>
</section>
<section anchor="sec-accounting" title="Accounting Commands">
<t>The DNCA reuses session based accounting as defined in the Diameter
Base Protocol<xref target="RFC3588"></xref> to report the bindings per
endpoint. This reporting is achieved by sending Diameter Accounting
Requests (ACR) [Start, Interim and Stop] from the DNCA Diameter peer
within the NAT-device to its associated DNCA Diameter peer within the
NAT-controller.</t>
<t>The DNCA Diameter peer within the NAT-device sends an ACR Start on
receiving a NCR with NC-Request-Type AVP set to INITIAL_REQUEST for a
session or on creation of the first binding for a session requested in
an earlier NCR. DNCA may send ACR Interim updates, if required, either
due to a change in bindings resulting from a NCR with NC-Request-Type
AVP set to UPDATE_REQUEST, or periodically as specified in
Acct-Interim-Interval by the DNCA Diameter peer within the
NAT-controller, or when it creates or tears down bindings. An ACR Stop
is sent by the DNCA Diameter peer within the NAT-device on receiving
STR.</t>
<t>The function of correlating the multiple bindings used by an endpoint
at any given time is relegated to the post processor.</t>
<t>The DNCA Diameter peer within the NAT-device may trigger an interim
accounting record when maximum number of bindings, if received in NCR,
is reached.</t>
<section title="NAT Control Accounting Messages">
<t>The ACR and ACA messages are reused as defined in Diameter Base
Protocol <xref target="RFC3588"></xref> for exchanging endpoint NAT
binding details between the DNCA Diameter peers. DNCA Application ID
is used in the accounting commands. ACR contains one or more optional
NAT-Control-Record AVP to report the bindings. The NAT-device
indicates the number of allocated NAT bindings to NAT-controller using
the Current-NAT-Bindings AVP. This number needs to match the number of
bindings identified as active within the NAT-Control-Record AVP.</t>
</section>
<section title="NAT Control Accounting AVPs">
<t>In addition to AVPs for ACR specified in <xref
target="RFC3588"></xref>, the DNCA Diameter peer within the NAT-device
must add the NAT-Control-Record AVP.</t>
<section anchor="avp_NAT-Control-Record" title="NAT-Control-Record">
<t>The NAT-Control-Record AVP (AVP code TBD) is of type Grouped. It
describes a binding and its status. If NAT-Control-Binding-Status is
set to Created, Event-Timestamp indicates the binding creation time.
If NAT-Control-Binding-Status is set to Removed, Event-Timestamp
indicates the binding removal time. If NAT-Control-Binding-Status is
active, Event-Timestamp need not be present; if a value is present,
it indicates that binding is active at the given time.</t>
<figure>
<artwork><![CDATA[ NAT-Control-Record ::= < AVP Header: TBD >
{ NAT-Control-Definition }
{ NAT-Control-Binding-Status }
[ Event-Timestamp ]]]></artwork>
</figure>
</section>
<section anchor="avp_NAT-Control-Binding-Status"
title="NAT-Control-Binding-Status">
<t>The NAT-Control-Binding-Status AVP (AVP code TBD) is of type
enumerated. It indicates the status of the binding - created,
removed, or active.</t>
<t>The following values are defined: <list style="empty">
<t>Created (1)<list style="empty">
<t>NAT binding is created.</t>
</list></t>
<t>Active (2)<list style="empty">
<t>NAT binding is active.</t>
</list></t>
<t>Removed (3)<list style="empty">
<t>NAT binding was removed.</t>
</list></t>
</list></t>
</section>
<section anchor="avp_Current-NAT-Bindings"
title="Current-NAT-Bindings">
<t>The Current-NAT-Bindings AVP (AVP code TBD) is of type
Unsigned32. It indicates number of NAT bindings active on
NAT-device.</t>
</section>
</section>
</section>
<section anchor="sec-avp-occurence-table" title="AVP Occurrence Table">
<t>The following sections presents the AVPs defined in this document and
specifies the Diameter messages in which, they MAY be present. Note:
AVPs that can only be present within a Grouped AVP are not represented
in this table.</t>
<t>The table uses the following symbols:</t>
<t><list style="empty">
<t><list hangIndent="10" style="hanging">
<t hangText="0">The AVP MUST NOT be present in the message.</t>
<t hangText="0+">Zero or more instances of the AVP MAY be
present in the message.</t>
<t hangText="0-1">Zero or one instance of the AVP MAY be present
in the message. It is considered an error if there is more than
one instance of the AVP.</t>
<t hangText="1">One instance of the AVP MUST be present in the
message.</t>
<t hangText="1+">At least one instance of the AVP MUST be
present in the message.</t>
</list></t>
</list></t>
<section title="DNCA AVP Table for NAT Control Initial and Update Requests">
<t>The following table lists DNCA specific AVPs that have to be
present in NCR and NCA with NC-Request-Type set to INITIAL_REQUEST or
UPDATE_REQUEST.</t>
<figure>
<artwork><![CDATA[ +-------------------+
| Command Code |
+-----------------------------------+-------------------+
| Attribute Name NCR NCA |
+-------------------------------------------------------+
|NC-Request-Type 1 1 |
|NAT-Control-Install 0-1 0 |
|NAT-Control-Remove 0-1 0 |
|NAT-Control-Definition 0 0 |
|Current-NAT-Bindings 0 0 |
|Duplicate-Session-Id 0 0-1 |
+-------------------------------------------------------+]]></artwork>
</figure>
</section>
<section title="DNCA AVP Table for Session Query request">
<t>The following table lists DNCA specific AVPs that have to be
present in NCR and NCA with NC-Request-Type set to QUERY_REQUEST.</t>
<figure>
<artwork><![CDATA[ +-------------------+
| Command Code |
+-----------------------------------+-------------------+
| Attribute Name NCR NCA |
+-------------------------------------------------------+
|NC-Request-Type 1 1 |
|NAT-Control-Install 0 0 |
|NAT-Control-Remove 0 0 |
|NAT-Control-Definition 0 0+ |
|Current-NAT-Bindings 0 1 |
|Duplicate-Session-Id 0 0 |
+-------------------------------------------------------+]]></artwork>
</figure>
</section>
<section title="DNCA AVP Table for Accounting Message">
<t>The following table lists DNCA specific AVPs, which may or may not
be present in ACR and ACA messages.</t>
<figure>
<artwork><![CDATA[ +-------------------+
| Command Code |
+-----------------------------------+-------------------+
| Attribute Name ACR ACA |
+-------------------------------------------------------+
|NAT-Control-Record 0+ 0 |
|Current-NAT-Bindings 1 0 |
+-------------------------------------------------------+
]]></artwork>
</figure>
</section>
</section>
<!-- -->
<!-- Possibly a 'Contributors' section ...
-->
<section anchor="IANA" title="IANA Considerations">
<t>This section contains the namespaces that have either been created in
this specification, or the values assigned to existing namespaces
managed by IANA.</t>
<t>In the subsections below, when we speak about review by a Designated
Expert, please note that the designated expert will be assigned by the
IESG. Initially, such Expert discussions take place on the AAA WG
mailing list.</t>
<section title="Application Identifier">
<t>This specification assigns the value <TBD>, 'Diameter NAT
Control Application', to the Application Identifier namespace defined
in <xref target="RFC3588"></xref>. See <xref target="sec-dnca"></xref>
for more information.</t>
</section>
<section title="Command Codes">
<t>This specification uses the value <TBD> from the Command code
namespace defined in <xref target="RFC3588"></xref> for the
NAT-Control-Request (NCR), NAT-Control-Answer (NCA) commands. See
<xref target="sec-dnca-ncr"></xref> and <xref
target="sec-dnca-nca"></xref> for more information on these
commands.</t>
</section>
<section title="AVP Codes">
<t>This specification assigns the values <TBD> from the AVP code
namespace defined in <xref target="RFC3588"></xref>. See <xref
target="tab-new-avps"></xref>for the assignment of the namespace in
this specification.</t>
</section>
<section title="Result-Code AVP Values ">
<t>This specification assigns the values <TBD> (4xxx, 5xxx,
5xxx, 5xxx, 5xxx,5xxx) from the Result-Code AVP value namespace
defined in <xref target="RFC3588"></xref>. See <xref
target="sec_result-codes"></xref> for the assignment of the namespace
in this specification.</t>
</section>
<section title="NC-Request-Type AVP">
<t>As defined in <xref target="avp_NC-Request-Type"></xref>, the
NC-Request-Type AVP includes Enumerated type values 1 - 3. IANA has
created and is maintaining a namespace for this AVP. All remaining
values are available for assignment by a Designated Expert <xref
target="RFC5226"></xref>.</t>
</section>
<section title="NAT-Control-Binding-Status AVP">
<t>As defined in <xref target="avp_NC-Request-Type"></xref>, the
NAT-Control-Binding-Status AVP includes Enumerated type values 1 - 3.
IANA has created and is maintaining a namespace for this AVP. All
remaining values are available for assignment by a Designated Expert
<xref target="RFC5226"></xref>.</t>
</section>
</section>
<section anchor="Security" title="Security Considerations">
<t>This document describes procedures for controlling NAT related
attributes and parameters by an entity, which is non-local to the device
performing NAT. This section discusses security considerations for DNCA.
This includes the interactions between the Diameter peers within a
NAT-controller and a NAT-device as well as general considerations for
NAT-control in a service provider network. </t>
<t>Security between NAT-controller and NAT-device has a number of
components: authentication, authorization, integrity, and
confidentiality.</t>
<t>Authentication refers to confirming the identity of an originator for
all datagrams received from the originator. Lack of authentication of
Diameter messages between the Diameter peers can jeopardize the
fundamental service of the peering network elements. A consequence of
not authenticating the message sender by the recipient would be that an
attacker could spoof the identity of a "legitimate" authorizing entity
in order to change the behavior of the receiver. An attacker could for
example launch a denial of service attack by setting the maximum number
of bindings for a session on the NAT-device to zero; provision bindings
on a NAT-device which include IP-addresses already in use in other parts
of the network; or request session termination of the Diameter session
and hamper a user's connectivity. Lack of authentication of a NAT-device
to a NAT-controller could lead to situations where the NAT-device could
provide a wrong view of the resources (i.e. NAT-bindings). In addition,
templates on the NAT-device specifying pre-defined binding rules could
be configured differently than expected by the NAT-controller. Failing
of any of the two DNCA Diameter peers to provide the required
credentials should be subject to logging.</t>
<t>Authorization refers to whether a particular authorizing entity is
authorized to signal a network element requests for one or more
applications, adhering to a certain policy profile. Failing the
authorization process might indicate a resource theft attempt or failure
due to administrative and/or credential deficiencies. In either case,
the network element should take the proper measures to log such
attempts.</t>
<t>Integrity is required to ensure that a Diameter message exchanged
between the Diameter peers has not been maliciously altered by
intermediate devices. The result of a lack of data integrity enforcement
in an untrusted environment could be that an impostor will alter the
messages exchanged between the peers. This could cause a change of
behavior of the peers, including the potential of a denial of
service.</t>
<t>Confidentiality protection of Diameter messages ensures that the
signaling data is accessible only to the authorized entities. When
signaling messages between the DNCA Diameter peers traverse untrusted
networks, lack of confidentiality will allow eavesdropping and traffic
analysis.</t>
<t>Diameter offers security mechanisms to deal with the functionality
demanded above. DNCA makes use of the capabilities offered by Diameter
and the underlying transport protocols to deliver these requirements
(see <xref target="sec-diameter-messages"></xref> ). If the DNCA
communication traverses untrusted networks, it is assumed that messages
between DNCA Diameter peers are secured using either IPsec or TLS.
Please refer to <xref target="RFC3588"></xref>, section 13 for details.
DNCA Diameter peers MAY perform bilateral authentication, authorization
as well as procedures to ensure integrity and confidentiality of the
information exchange.</t>
<t>It is assumed that the DNCA Diameter peers are typically in the same
domain and have a mutual trust set up. This document does not specify a
mechanisms for authorization between the DNCA Diameter peers. It is
assumed that the DNCA Diameter peers are provided with sufficient
information to make an authorization decision. The information can come
from various sources, for example the peering devices could store local
authentication policy, listing the identities of authorized peers.</t>
<t>Any mechanism or protocol providing control of a NAT-device, and DNCA
is an example of such a control mechanism, could allow for misuse of the
NAT-device given that it enables the definition of per-destination or
per-source rules. Misuse could include anti-competitive practices among
providers, censorship, crime, etc. NAT-control could be used as a tool
for preventing or redirecting access to particular sites. For instance,
by controlling the NAT bindings, one could ensure that end points aren't
able to receive particular flows, or that those flows are redirected to
a relay that snoops or tampers with traffic instead of directly
forwarding the traffic to the intended end point. In addition one could
setup a binding in a way that the source IP address used is one of a
relay so that traffic coming back can be snooped on or interfered with.
The protections on DNCA and its Diameter protocol exchanges don't
prevent such abuses of NAT-control. A service provider deploying DNCA
needs to make sure that higher layer processes and procedures are put in
place which allow them to detect and mitigate misuses.</t>
</section>
<section title="Acknowledgements">
<t>The authors would like to thank Wesley Eddy, Miguel A. Garcia, Jouni
Korhonen, Matt Lepinski, Avi Lior, Chris Metz, Pallavi Mishra, Lionel
Morand, Hannes Tschofenig, Shashank Vikram, Greg Weber, and Glen Zorn
for their input on this document.</t>
</section>
<section title="Change History (to be removed prior to publication as an RFC) ">
<t>Changes from -00 to -01</t>
<t><list style="letters">
<t>new values for Result-Code AVP used - instead of
Experimental-Result AVP</t>
<t>added support for transport specific binding (UDP/TCP)</t>
<t>added support for twice-NAT</t>
<t>clarified the use of the two different types of
query-requests</t>
</list></t>
<t>Changes from -01 to -02</t>
<t><list style="letters">
<t>Reference to pull mode removed, session initiation event
clarified in section 4.1</t>
<t>added Redirect-* AVPs in NCA command</t>
<t>Removed reference to Called-Station-Id AVP in NCR command</t>
<t>Editorial changes</t>
<t>added support for bindings providing AFT (NAT64)</t>
</list>Changes from -02 to -03<list style="letters">
<t>Editorial changes</t>
</list>Changes from -03 to -04<list style="letters">
<t>Editorial changes suggested in WG last call review</t>
<t>Removed NCR Request type terminate and replaced with STR</t>
<t>All references to Auth-Session-State are removed and a new
section to describe FSM for Manager and Agent has been added</t>
<t>Clarified reuse of External address and address pools among
multiple subscribers</t>
</list>Changes from -04 to -05<list style="letters">
<t>Removed references to Large Scale NAT as per review comments</t>
</list>Changes from -05 to -06<list style="letters">
<t>Editorial changes</t>
</list>Changes from -06 to -07<list style="letters">
<t>Added a note in section 4.3 stating the state of pre-existing
bindings on update failure</t>
<t>Security considerations are made consistent between sections 5.1
and 12</t>
<t>Editorial changes</t>
</list>Changes from -07 to -08<list style="letters">
<t>Added section 4.6 to describe session abort</t>
<t>Editorial changes</t>
<t>Nomenclature change: From DNCA Agent/Manager to DNCA Diameter
peers identifying the location where they reside (NAT-controller or
NAT-device)</t>
<t>IANA consideration Section format changes</t>
<t>Updated security section (included considerations directly,
rather than referring to Diameter QoS similarities).</t>
</list></t>
<t>Changes from -08 to -09</t>
<t><list style="letters">
<t>expanded on the need for an SP controlling the maximum number of
bindings of an end point (see introduction section)</t>
<t>added a paragraph in the security section outlining general
mis-uses of NAT-control (non specific to DNCA), with DNCA being an
example of such a NAT-control protocol</t>
<t>editorial changes</t>
</list></t>
</section>
</middle>
<!-- *****BACK MATTER ***** -->
<back>
<!-- References split into informative and normative -->
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(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="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?-->
&RFC2119;
&RFC3588;
&RFC4675;
&RFC5777;
&RFC5226;
<reference anchor="ETSIES283034">
<front>
<title>Telecommunications and Internet Converged Services and
Protocols for Advanced Networks (TISPAN),Network Attachment
Sub-System (NASS),e4 interface based on the Diameter
protocol.</title>
<author fullname="ETSI" surname="ETSI">
<organization></organization>
</author>
<date month="September" year="2008" />
</front>
</reference>
&RFC4005;
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 04:22:25 |