One document matched: draft-ietf-dime-nat-control-02.xml
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<rfc category="std" docName="draft-ietf-dime-nat-control-02" ipr="trust200902">
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<!-- ***** FRONT MATTER ***** -->
<front>
<!-- The abbreviated title is used in the page header - it is only necessary if the
full title is longer than 39 characters -->
<title abbrev="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>Mavenir Systems</organization>
<address>
<postal>
<street>Sharda Towers, 56/13 Nandidurga Road</street>
<city>Bangalore 560046</city>
<country>India</country>
</postal>
<email>vaneeta@mavenir.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 month="March" year="2010" />
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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
(DNCA), allowing for per-endpoint control of large scale NAT/NAPT
devices, which are put in place to cope with IPv4-address space
completion. The DNCA allows external devices to configure and manage a
NAT device - expanding the existing Diameter-based AAA and policy
control capabilities with a NAT/NAPT control component. These external
devices can be network elements in the data plane such as a Network
Access Server (NAS), or can be more centralized control plane devices
such as AAA-servers. DNCA establishes a context to commonly identify and
manage endpoints on a gateway or server, and a large scale NAPT/NAT
device. This includes, for example, the control of the total number of
NAT-bindings allowed or the allocation of a specific NAT-binding for a
particular endpoint. In addition, it allows large scale NAT 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) at
the edge of their networks to deal with the depletion of available
public IPv4 addresses. This document defines a Diameter application for
providers deploying such NATs and NAPT devices. The use of a Diameter
application allows for simple integration into the existing AAA
environment of a provider.</t>
<t>The Diameter NAPT Control Application (DNCA) offers the following
capabilities:</t>
<t><list style="numbers">
<t>Limit/Define the number of NAPT/NAT-bindings made available to an
individual subscriber or end point.</t>
<t>Support 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 as
well as the external IP-address/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 will be 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 (e.g. SIP-proxy server
deployments).</t>
</list></t>
<t>Define 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, 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 will contain
a description of the IP- address pool(s) to be used (e.g. list of
IP-subnets).</t>
<t>Accounting/Reporting: Report established bindings for a
particular user. The collected information is used by accounting
systems, for statistical purposes, etc.</t>
<t>Query functionality to retrieve details about bindings on demand.
This feature complements the previously mentioned accounting
functionality mentioned above (see item 4). The query functionality
complements alternative information query mechanisms such as
SNMP-based mechanisms, if available.</t>
<t>Common identification of a subscriber or endpoint on multiple
network devices such as the NAPT/NAT 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, 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 the Diameter NAPT Control
Application and its overall deployment framework. Sections 4 to 8 cover
the DNCA specifics, with Section 4 describing session management,
Section 5 the use of the Diameter base protocol, Section 6 new commands,
Section 7 the respective AVPs used, and Section 8 accounting aspects.
Section 9 presents an AVP occurance 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 are used in this document:</t>
<t><list style="empty">
<t>AAA: Authentication, Authorization, Accounting</t>
<t>DNCA: Diameter NAT 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>NAS: Network Access Server</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 Network Access Server (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-LSN-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 optionally
protocol) 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
would be hampered. Provisioning static NAT-bindings for particular
endpoints, using different public IP-address pools for different set
of endpoints (e.g. residential or business customers), as well as
reporting on the allocated bindings on a per-endpoint basis would be
burdensome for a service provider if the NAT device would not be aware
of endpoints and allow for per-endpoint control and management which
easily integrates with the already existing per-endpoint management
infrastructure of the service provider.</t>
<figure anchor="fig-LSN-deployment"
title="Access network deployment with LSN">
<artwork><![CDATA[ +---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | | | | | IPv4 |
| Host |----| NAS |----| NAT |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Private IPv4 -----------><--- Public IPv4 --->
<-------- Public IPv6 -----------><--- Public IPv4 --->]]></artwork>
</figure>
</section>
<section title="Diameter NAPT Control Application Overview">
<t>The Diameter NAT Control Application runs between a Diameter NAT
Control Application Agent on the NAT and the Diameter NAT Control
Application Manager. DNCA allows for per-endpoint control and
management of a NAT. Being 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 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, to provide per endpoint reporting on the
allocated NAT-bindings, as well as to provide for unique
identification of an endpoint on both NAT, AAA-server and NAS, thus
simplifying the correlation of accounting data streams.</t>
<t>DNCA allows for controlling the behavior of a NAT device on a
per-endpoint basis during initial session establishment as well as 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 The Diameter NAPT Control Application">
<t>Deployment dependent, the role of the Diameter NAT Control Manager
can be fulfilled by either the NAS or by an external server such as an
AAA-server. The two deployment scenarios are outlined in <xref
target="fig-LSN-integrated-deployment"></xref> (“integrated
deployment”) and <xref
target="fig-LSN-autonomous-deployment"></xref> (“autonomous
deployment”).</t>
<t>Within the figures (M) denotes the network element which takes on
the DNCA manager role. Similarly, (A) identifies the network element
which performs the DNCA agent role.</t>
<t>The integrated deployment approach hides the existence of the NAT
device from external servers such as the AAA-server as much as
possible. It is suited for environments where minimal changes to the
existing AAA deployment are desired. The NAS, taking the role of the
DNCA manager, is in charge of initiating and managing the session to
the NAT device, exchanging NAT specific configuration information as
well as handling reporting and accounting information. The NAS
receives reporting and accounting information from NAT device. This
way the NAS can provide for a single accounting record for the user,
offloading external accounting systems from correlating accounting
information received from multiple sources.</t>
<t>An example network attachment for an integrated NAT deployment
could be described as follows: An endpoint connects to the network,
with the NAS being the point of attachment. After successful
authentication, 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. NAS will initiate a DNCA session to the NAT and send
the relevant authorization and configuration information for the
particular endpoint to the NAT device. This could comprise e.g.
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 or accounting requirements. The
NAT device will send its per-endpoint accounting information to the
NAS which aggregates the accounting information received form the NAT
with its local accounting information for the endpoint into a single
accounting stream towards the AAA-server.</t>
<figure anchor="fig-LSN-integrated-deployment"
title="LSN Control deployment: Integrated deployment">
<artwork><![CDATA[ +---------+
| |
| AAA |
| |
+---------+
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | (M) | | (A) | | IPv4 |
| Host |----| NAS |----| NAT |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><--- Public IPv4 ---->
<-------- Private IPv4 ----------><--- Public IPv4 ---->
]]></artwork>
</figure>
<t>The autonomous deployment approach decouples user management on NAS
and NAT device. The AAA system performing the role of the DNCA manager
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-LSN-autonomous-deployment"
title="LSN Control deployment: Autonomous deployment">
<artwork><![CDATA[ +---------+
| (M) |
| AAA |
| |
+---------+
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | | | (A) | | IPv4 |
| Host |----| NAS |----| NAT |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><---- Public IPv4 --->
<-------- Private IPv4 ----------><---- Public IPv4 --->]]></artwork>
</figure>
</section>
</section>
<section anchor="sec-dnca"
title="Diameter NAT Control Application Session Establishment and Management">
<t>Note that this section forward references some of the commands and
AVPs defined for the DNCA. Please refer to <xref
target="sec-dnca-commands"></xref> and <xref
target="sec-dnca-avps"></xref> for details.</t>
<section title="Parties Involved ">
<t>Authorization and control models supported by this application
include the following parties: <list style="symbols">
<t>Diameter NAT Control Application (DNCA) agent: The DNCA agent
is part of the Large scale NAT (NAT) device</t>
<t>Diameter NAT Control Application (DNCA) manager</t>
</list></t>
<t>The NAT control requesting entity is always the DNCA manager.
Sessions will always be initiated, updated, or terminated by the DNCA
manager. This mode of operation is sometimes also referred to as "push
mode".</t>
<t>DNCA manager can be NAS or AAA Server. DNCA manager will initiate a
session with DNCA agent when it learns about the subscriber. DNCA
manager may learn about a subscriber when it receives authentication,
authorization or accounting request for that subscriber or by some
other means such as on the box configuration to identify subscriber
w.r.t IP packets.</t>
</section>
<section title="Session Establishment">
<t>The DNCA manager establishes a session to the DNCA agent to control
the behavior of the NAT device. During session establishment, the DNCA
manager will pass along configuration information to the DNCA agent.
Session configuration information could for example comprise 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, external
addresses should be allocated from.</t>
<t>The DNCA manager initiates the Diameter NAT Control session to the
DNCA agent. The DNCA manager generates a NAT-Control Request (NCR)
message to the DNCA agent with NC-Request-Type AVP set to
INITIAL_REQUEST. On receipt of the NCR the DNCA agent will setup a new
session for the endpoint associated with the endpoint classifier(s)
contained in the NCR. The DNCA agent notifies the DNCA manager 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 protocol
interaction between the DNCA manager and the DNCA agent.</t>
<t>The initial NAT-Control-Request can contain configuration
information for the session which specifies the behavior of the NAT
for the session. Configuration information which can be included
comprises: <list style="symbols">
<t>A list of NAT-bindings which should be pre-allocated for the
session (e.g. in case a subscriber 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 address pool(s) to be used for
the session.</t>
<t>A reference to a predefined binding rule on DNCA agent that
will be applied to the session. Such a predefined binding rule on
DNCA agent may contain, for example, the name of the IP-address
pool that external IP-addresses should be allocated from, maximum
number of bindings permitted for the endpoint etc.</t>
</list></t>
<t>In certain cases, the DNCA agent may not be able to perform the
tasks requested within the NCR. These include the following: <list
style="symbols">
<t>If a DNCA agent receives a NCR from a DNCA manager with NC-
Request-Type AVP set to INITIAL_REQUEST that identifies an already
existing session (i.e. DNCA manager and endpoint identifier match
an already existing session), the DNCA agent will return NCA with
Result-Code set to SESSION_EXISTS, and provides Session-Id of the
existing session in Duplicate-Session-Id AVP.</t>
<t>If a DNCA agent receives an NCR from a DNCA manager with NC-
Request-Type AVP set to INITIAL_REQUEST that matches more than one
of the already existing sessions (i.e. DNCA manager and endpoint
identifier match already existing sessions), the DNCA agent will
return a NCA with Result-Code set to Insufficient-Classifiers. In
case a DNCA manager receives a NCA that reports
Insufficient-Classifiers, it may choose to retry establishing a
new session using additional/more specific classifiers.</t>
<t>If the NCR contains a binding rule not defined on the NAT, the
DNCA agent will return a NCA with Result-Code AVP set to
UNKNOWN_BINDING_RULE.</t>
<t>In case the DNCA agent is unable to establish all of the
bindings requested in the NCR, it will return a NCA with
Result-Code set to BINDING_FAILURE. The DNCA agent (i.e. NAT)
treats a NCR as an atomic operation; hence none of the requested
bindings will be established by NAT. Either all requested actions
within a NCR are completed successfully, or the entire request
fails.</t>
<t>If DNCA agent does not have sufficient resources to process a
request, it will return 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 (i.e. a
predefined template on NAT) 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[ DNCA Manager DNCA Agent
| |
| |
| |
Trigger |
| |
| NCR |
|------------------------------------------>|
| (INITIAL_REQUEST, endpoint classifier, |
| session id, NAT control config data) |
| |
| |
| Create session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |]]></artwork>
</figure>
</section>
<section title="Session Re-Authorization">
<t>Session re-authorization is performed if the DNCA manager desires
to change the behavior of the NAT for an existing 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 manager generates a NAT-Control Request (NCR) message to
the DNCA agent with NC-Request-Type AVP set to UPDATE_REQUEST upon
receiving a trigger signal. In case the session is updated
successfully, the DNCA agent notifies the DNCA manager about
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 DNCA manager and the DNCA agent.</t>
<t>In certain cases, the DNCA agent may not be able to perform the
tasks requested within the NCR. These include the following: <list
style="symbols">
<t>If DNCA agent receives a NCR update/query request for
non-existent session it will set error code in answer, to
DIAMETER_UNKNOWN_SESSION_ID.</t>
<t>If the NCR contains a binding rule not defined on the NAT, the
DNCA agent will return a NCA with Result-Code AVP set to
UNKNOWN_BINDING_RULE.</t>
<t>If the DNCA agent cannot establish the requested binding
because the maximum number of allowed bindings has been reached
for the Endpoint Classifier, it will return NCA with Result-Code
AVP set to MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT.</t>
<t>In case the DNCA agent 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 subscriber, it will return a
NCA with Result-Code set to BINDING_FAILURE. The DNCA agent (i.e.
NAT) treats a NCR as an atomic operation; hence none of the
requested bindings will be established by NAT. Either all
requested actions within a NCR are completed successfully, or the
entire request fails.</t>
<t>If DNCA agent does not have sufficient resources to process a
request, it will return a NCA with Result-Code set to
RESOURCE_FAILURE.</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 how NAT would cope with a case where the new value is
lower than the actual number of allocated bindings. Typically the
NAT would refrain from enforcing the new limit immediately (i.e.
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 DNCA
agent, the binding rule will override any previously defined rules
for the session.</t>
<t>In case Max-NAT-Binding and Nat-Control-Definition AVPs are
included in the NCR along with a reference to a binding rule (i.e.
a predefined template on NAT) 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></t>
<figure anchor="fig-session-re-auth"
title="NAT Control request for session update ">
<artwork><![CDATA[ DNCA Manager DNCA Agent
| |
| |
| |
Change of session |
attributes |
| |
| NCR |
|------------------------------------------>|
| (UPDATE_REQUEST session id, |
| NAT control config data) |
| |
| |
| Update session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |]]></artwork>
</figure>
</section>
<section title="Session And Binding Query">
<t>Session query can be used by the DNCA manager to either retrieve
information on the current bindings for a particular session at the
NAT or discover the session identifier for a particular external
IP-address/port pair.</t>
<t>The DNCA manager initiates a session query by sending a NAT-Control
Request (NCR) message to the DNCA agent with NC-Request-Type AVP set
to QUERY_REQUEST. <xref target="fig-session-query"></xref> shows the
protocol interaction between the DNCA manager and the DNCA agent.</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 manager retrieve the current set of bindings for a specific
session. The second type of query request is used in to retrieve the
session identifiers, along with the associated bindings, matching a
criteria. This enables the DNCA manager to find out which sessions
utilize a specific external IP address.</t>
<t><list style="numbers">
<t>Request a list of currently allocated NAT-bindings for a
particular session: The DNCA agent will, on receipt of the NCR,
lookup the session information for the session id contained in the
NCR, and will report all currently active NAT-bindings for the
session using a NAT-Control Answer (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 will be reported in a
NAT-Control-Definition AVP. In case the session id is unknown to
the DNCA agent a DIAMETER_UNKNOWN_SESSION_ID error is
returned.</t>
<t>Retrieve session ids and internal IP-address/port pairs for one
or multiple external IP-address/port pairs: If the DNCA manager
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 used within the NCR is not meaningful
for this type of a query. The DNCA agent will report the
NAT-bindings and associated session ids corresponding to the
external IP-address/port pairs in a NAT-Control Answer (NCA)
message with Result-Code set to DIAMETER_SUCCESS and the same
session id as the one used in the 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[ DNCA Manager DNCA Agent
| |
| |
| |
DNCA Session Established |
| |
| NCR |
|------------------------------------------>|
| (QUERY_REQUEST) |
| |
| |
| |
| Look up corresponding session
| and associated NAT Bindings
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |]]></artwork>
</figure>
</section>
<section title="Session Termination">
<t>The DNCA manager generates a NAT-Control Request (NCR) message to
the DNCA agent with NC-Request-Type AVP set to TERMINATE_REQUEST upon
receiving a trigger signal. The DNCA agent sends accounting stop
record reporting all the bindings and notifies the DNCA manager about
successful session termination using a NAT-Control Answer (NCA)
message with Result-Code set to DIAMETER_SUCCESS. <xref
target="fig-session-terminate"></xref> shows the protocol interaction
between the DNCA manager and the DNCA agent.</t>
<t>If a DNCA agent receives a NCR from a DNCA manager with
NC-Request-Type AVP set to TERMINATE_REQUEST and fails to find a
matching session, the DNCA agent returns DIAMETER_UNKNOWN_SESSION_ID
error.</t>
<figure anchor="fig-session-terminate"
title="Terminate NAT Control session">
<artwork><![CDATA[ DNCA Manager DNCA Agent
| |
| |
Trigger |
| |
| NCR |
|------------------------------------------->|
| (TERMINATE_REQUEST, session id) |
| |
| |
| Remove NAT bindings
| of session
| |
| |
| Send accounting stop |
|<-------------------------------------------|
| for all session bindings |
| |
| Terminate Session /
| Remove session state
| |
| |
| |
| NCA |
|<-------------------------------------------|
| (result code) |
| |]]></artwork>
</figure>
</section>
<section title="DNCA Manager/Agent Failures">
<t>This document does not cover details in case DNCA manager and DNCA
agent go out of sync, which could happen for example due to DNCA
manager or DNCA agent restart, (temporary) loss of network
connectivity etc. DNCA application will rely on DNCA Manager and DNCA
Agent to have builtin redundancy support to recover state in case of
failure.</t>
<t>Example failure cases include the following:</t>
<t><list style="symbols">
<t>The DNCA manager loses session state (e.g. due to a restart).
In this case, <list style="symbols">
<t>the DNCA agent may receive a NCR with NC-Request-Type AVP
set to INITIAL_REQUEST that matches an existing session of
DNCA agent. The DNCA agent will return an error that contains
Duplicate-Session-Id AVP to report Session-Id of existing
session. The DNCA manager may then send an explicit
TERMINATE_REQUEST for the older session that was lost.</t>
<t>the DNCA manager may receive accounting records for a
session that does not exist. The DNCA manager will send an
accounting answer with error-code set to
DIAMETER_UNKNOWN_SESSION_ID. On receipt of which the DNCA
agent clears the session and removes the associated session
state.</t>
</list></t>
<t>The DNCA agent loses session state. In such a case, the DNCA
agent could receive a NCR with NC-Request-Type AVP set to
UPDATE_REQUEST for a non-existent session. The DNCA agent will
return NCA with error code set to DIAMETER_UNKNOWN_SESSION_ID.
State recovery procedures of the DNCA agent will be covered in a
future version of this document.</t>
<t>The DNCA manager is unreachable (as e.g. detected by Diameter
watchdog) or down and accounting requests from the DNCA agent fail
to get a response. The mechanism to ensure that a DNCA manager no
longer has associated state for a session being cleared at the
DNCA agent is beyond the scope of this document.</t>
<t>The DNCA agent 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 terminate the access session to the
endpoint.</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>
shall apply, 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, IPSec MAY be used.</t>
<t>The DNCA agent MAY verify the identity of the DNCA Manager during
the Capabilities Exchange Request procedure.</t>
<t>The DNCA agent MAY verify if the DNCA Manager that issues a NCR
command is allowed to do so, based on: <list style="symbols">
<t>The Identity of the DNCA Manager</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 agent and DNCA manager maintain
state associated with the Session-Id. This globally unique Session-Id
is used for updating, accounting for and terminating the session. DNCA
session MUST NOT have more than one outstanding request at any given
instant. The DNCA agent 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 manager knows the DiameterIdentity of
the DNCA agent for a given endpoint. Both the Destination-Realm and
Destination-Host AVPs are present in the Request from the DNCA manager
to the DNCA agent.</t>
</section>
<section title="Advertising Application Support">
<t>Diameter applications conforming to this specification MUST
advertise support by including the value of TBD in:</t>
<t><list style="symbols">
<t>Auth-Application-Id and Acct-Application-Id of
Capabilities-Exchange-Request (CER)</t>
<t>Auth-Application-Id of NC-request (NCR), NC-Answer (NCA),
Abort-Session-Request(ASR), Abort-Session-Answer (AAA)
messages</t>
<t>Acct-Application-Id in Accounting-Request (ACR) and
Accounting-Answer (AAA) messages.</t>
</list></t>
</section>
</section>
<section anchor="sec-dnca-commands"
title="Diameter NAT Control Application Commands">
<t>The following commands are used to establish, maintain and clear 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 manager to the DNCA agent 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 subscriber.</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 ]
[ Auth-Session-State ]
* [ NAT-Control-Remove ]
* [ 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 agent 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 }
{ NC-Request-Type }
[ Result-Code ]
* [ 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 ]
* [ AVP ]
]]></artwork>
</figure>
</section>
</section>
<section anchor="sec-dnca-avps"
title="Diameter NAT Control Application 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 |
|Auth-Session-State 277 Enumerated | 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 agent 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>Result-Code AVP values that 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 agent indicates that the binding could not be
installed or a new session could not be created due to
resource shortage.</t>
</list>BINDING_FAILURE (TBD)<list style="empty">
<t>The DNCA indicates that the requested binding(s) could
not be installed.</t>
</list></t>
<t>MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT (TBD)<list
style="empty">
<t>The DNCA agent 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 agent denies request to initialize a new
session, if it already has a DNCA session that uses the same
set of classifiers as indicated by DNCA manager in the new
session init request.</t>
</list></t>
<t>INSUFFICIENT_CLASSIFIERS (TBD)<list style="empty">
<t>The DNCA agent defines request to initialize a new
session, if the classifiers in the request match more than
one of the existing sessions on DNCA agent.</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 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 from Diameter QoS Application">
<t>The following AVPs are reused from the Diameter QoS Application
<xref target="I-D.ietf-dime-diameter-qos"></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 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="Diameter NAT Control Application Defined AVPs">
<t>The following table describes the new Diameter AVPs used in the
present document, their AVP Code values, types, possible flag values
and whether the AVP may or not be encrypted.</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 7.7.1 Enumerated | M | P | Y |
|NAT-Control-Install TBD 7.7.2 Grouped | M | P | Y |
|NAT-Control-Remove TBD 7.7.3 Grouped | M | P | Y |
|NAT-Control-Definition TBD 7.7.4 Grouped | M | P | Y |
|NAT-Internal-Address TBD 7.7.5 Grouped | M | P | Y |
|NAT-External-Address TBD 7.7.6 Grouped | M | P | Y |
|Max-NAT-Bindings TBD 7.7.7 Unsigned32 | M | P | Y |
|NAT-Control- TBD 7.7.8 OctetString| M | P | Y |
| Binding-Rule | | | |
|Duplicate- TBD 7.7.9 UTF8String | M | P | Y |
| Session-ID | | | |
|NAT-Control-Record TBD 8.2.1 Grouped | M | P | Y |
|NAT-Control- TBD 8.2.2 Enumerated | M | P | Y |
| Binding-Status | | | |
|Current-NAT-Bindings TBD 8.2.3 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. |
|V - Vendor specific bit that indicates whether the optional |
| Vendor-ID field is present in the AVP header |
+-------------------------------------------------------------------+]]></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 used to install binding at the DNCA
agent on a successful access session setup.</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>TERMINATION_REQUEST (3) <list style="empty">
<t>Termination Request is used to deactivate and remove all
bindings previously activated on a given access session.</t>
</list></t>
<t>QUERY_REQUEST (4)<list style="empty">
<t>Query Request is used to query the DNCA agent 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 maximum number of NAT bindings to be allowed
for a subscriber and NAT-Control-Binding-Rule that references
predefined policy template on DNCA agent that may contain static
bindings, maximum number of bindings to be allowed, address pool
from which external binding address 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 agent and the DNCA manager.</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 which the
binding is created. Exactly zero or one Protocol AVP may be
contained within NAT-Control-Definition AVP. If the Protocol AVP is
omitted and if both internal and external address are specified then
the binding reserves the addresses for all transport protocols.</t>
<t>The Direction AVP is of type Enumerated and specifies in which
direction to apply the binding. The values of the enumeration
applicable in this context are: "IN","OUT". If Direction AVP is OUT
or absent NAT-Internal-Address refers to the address of the
subscriber device that needs to be translated. If Direction AVP is
"IN" NAT-Internal-Address is the destination 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,
and 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 Framed-IP-Address AVP
is present.</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,
and it indicates the maximum number of NAT bindings allowed.</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 is of
type OctetString, and it defines a name for a policy template that
will be predefined at NAT. Details on the contents and structure of
the template as well as how it would be configured are outside the
scope of this document. The policy to which this AVP refers to may
contain NAT Bindings, address pool for external address allocation
of NAT binding, maximum allowed NAT bindings etc.</t>
</section>
<section anchor="avp_Duplicate-Session-Id"
title="Duplicate-Session-Id AVP">
<t>The Duplicate-Session-Id AVP (AVP Code TBD) is of is of type
UTF8String. It is used to report error and contains the Session-Id
of an existing session.</t>
</section>
</section>
</section>
<section anchor="sec-accounting" title="Accounting Commands">
<t>The Diameter NAT Control Application reuses session based accounting
as defined in Diameter Base Protocol <xref target="RFC3588"></xref> to
report the bindings used per endpoint. This reporting is achieved by
sending Diameter Accounting Requests (ACR) [Start, Interim and Stop]
from the DNCA agent to DNCA manager.</t>
<t>The DNCA agent sends an ACR Start on receiving an NCR with
NC-Request-Type AVP set to INITIAL_REQUEST received for a session, or on
creation of the first binding for a session requested in an earlier NCR.
The DNCA may send ACR Interim updates, if required, either due to a
change in bindings resulting from an NCR with NC-Request-Type AVP set to
UPDATE_REQUEST, or periodically as specified in Acct-Interim-Interval by
DNCA Manager or when it creates/tears down bindings. An ACR Stop is sent
by the DNCA agent on receiving an NCR with NC-Request-Type AVP set to
TERMINATION_REQUEST.</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 agent 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 agent and the CDF. DNCA Application
ID is used in the accounting commands. ACR will contain one or more
optional NAT-Control-Record AVP to report the bindings. The DNCA agent
indicates the number of the currently allocated NAT bindings to the
DNCA manager 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 agent 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, and
it describes a binding and its status. Event-Timestamp indicates the
time at which binding was created if NAT-Control-Binding-Status is
set to Created, or time at which the binding was removed if
NAT-Control-Binding-Status is set to removed. If the
NAT-Control-Binding-Status is active Event-Timestamp need not be
present, if present it indicates that binding is active at the
mentioned 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 and it describes whether the binding being reported was
created or removed or simply indicates that it is active.</t>
<t>The following values are defined: <list style="empty">
<t>Created (1)<list style="empty">
<t>Indicates that NAT binding is created.</t>
</list></t>
<t>Active (2)<list style="empty">
<t>Indicates that NAT binding is active.</t>
</list></t>
<t>Removed (3)<list style="empty">
<t>Indicates that the 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, and it indicates number of NAT bindings active on
NAT.</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 in which Diameter messages they MAY be present. Note that 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 presents which NAT control application specific
AVPs are to be present in NCR/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 |
|NAT-Control-Record 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 presents which NAT control application specific
AVPs are to be present in NCR/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+ |
|NAT-Control-Record 0 0 |
|Current-NAT-Bindings 0 1 |
|Duplicate-Session-Id 0 0 |
+-------------------------------------------------------+]]></artwork>
</figure>
</section>
<section title="DNCA AVP Table for NAT Control Terminate requests">
<t>The following table presents which NAT control application specific
AVPs are to be present in NCR/NCA with NC-Request-Type set to
TERMINATION_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 |
|NAT-Control-Record 0 0 |
|Current-NAT-Bindings 0 0 |
|Duplicate-Session-Id 0 0 |
+-------------------------------------------------------+]]></artwork>
</figure>
</section>
<section title="DNCA AVP Table For Accounting Message">
<t>Following table presents which NAT control application specific
AVPs May or May Not be present in ACR/ACA messages.</t>
<figure>
<artwork><![CDATA[ +-------------------+
| Command Code |
+-----------------------------------+-------------------+
| Attribute Name ACR ACA |
+-------------------------------------------------------+
|NC-Request-Type 0 0 |
|NAT-Control-Install 0 0 |
|NAT-Control-Remove 0 0 |
|NAT-Control-Definition 0 0 |
|NAT-Control-Record 0+ 0 |
|Current-NAT-Bindings 1 0 |
|Duplicate-Session-Id 0 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 had their values assigned to existing namespaces
managed by IANA.</t>
<section title="Command Codes">
<t>IANA is requested to allocate command code values for the
following.</t>
<t>Registry:</t>
<texttable align="right" anchor="table_command-codes"
suppress-title="true" title="Command codes">
<ttcol align="left">Code Value</ttcol>
<ttcol align="left">Name</ttcol>
<ttcol align="left">Reference</ttcol>
<c>to be assigned</c>
<c>NAT-Control-Request (NCR)</c>
<c><xref target="sec-dnca-ncr"></xref></c>
<c>to be assigned</c>
<c>NAT-Control-Answer (NCA)</c>
<c><xref target="sec-dnca-nca"></xref></c>
</texttable>
<t></t>
</section>
<section title="AVP Codes">
<t>IANA is requested to allocate AVP codes for the following AVPs that
are defined in this document.</t>
<t>Registry:</t>
<texttable align="right" anchor="table_avp-codes"
suppress-title="true" title="AVP codes">
<ttcol align="left">Code Value</ttcol>
<ttcol align="left">Name</ttcol>
<ttcol align="left">Reference</ttcol>
<c>to be assigned</c>
<c>NC-Request-Type</c>
<c><xref target="avp_NC-Request-Type"></xref></c>
<c>to be assigned</c>
<c>NAT-Control-Install</c>
<c><xref target="avp_NAT-Control-Install"></xref></c>
<c>to be assigned</c>
<c>NAT-Control-Remove</c>
<c><xref target="avp_NAT-Control-Remove"></xref></c>
<c>to be assigned</c>
<c>NAT-Control-Definition</c>
<c><xref target="avp_NAT-Control-Definition"></xref></c>
<c>to be assigned</c>
<c>NAT-Internal-Address</c>
<c><xref target="avp_NAT-Internal-Address"></xref></c>
<c>to be assigned</c>
<c>NAT-External-Address</c>
<c><xref target="avp_NAT-External-Address"></xref></c>
<c>to be assigned</c>
<c>Max-NAT-Bindings</c>
<c><xref target="avp_Max-NAT-Bindings"></xref></c>
<c>to be assigned</c>
<c>NAT-Control-Binding-Rule</c>
<c><xref target="avp_NAT-Control-Binding-Rule"></xref></c>
<c>to be assigned</c>
<c>Duplicate-Session-Id</c>
<c><xref target="avp_Duplicate-Session-Id"></xref></c>
<c>to be assigned</c>
<c>NAT-Control-Record</c>
<c><xref target="avp_NAT-Control-Record"></xref></c>
<c>to be assigned</c>
<c>NAT-Control-Binding-Status</c>
<c><xref target="avp_NAT-Control-Binding-Status"></xref></c>
<c>to be assigned</c>
<c>Current-NAT-Bindings</c>
<c><xref target="avp_Current-NAT-Bindings"></xref></c>
</texttable>
</section>
<section title="AVP Values">
<t></t>
<section title="Result-Code AVP Values">
<t><xref target="sec_result-codes"></xref> defines several new
values for the Result-Code AVP for transient failures and permanent
failures. IANA is requested to allocate the corresponding values
from the ranges for transient (4xxx) and permantent (5xxx)
failures.</t>
<texttable align="right" anchor="table_result-code-avps"
suppress-title="true" title="Result Code AVP Values">
<ttcol align="left">Code Value</ttcol>
<ttcol align="left">Name</ttcol>
<ttcol align="left">Reference</ttcol>
<c>to be assigned (4xxx)</c>
<c>RESOURCE_FAILURE</c>
<c><xref target="sec_result-code-transient"></xref></c>
<c>to be assigned (5xxx)</c>
<c>UNKNOWN_BINDING_RULE_NAME</c>
<c><xref target="sec_result-code-permanent"></xref></c>
<c>to be assigned (5xxx)</c>
<c>BINDING_FAILURE</c>
<c><xref target="sec_result-code-permanent"></xref></c>
<c>to be assigned (5xxx)</c>
<c>MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT</c>
<c><xref target="sec_result-code-permanent"></xref></c>
<c>to be assigned (5xxx)</c>
<c>SESSION_EXISTS</c>
<c><xref target="sec_result-code-permanent"></xref></c>
<c>to be assigned (5xxx)</c>
<c>INSUFFICIENT_CLASSIFIERS</c>
<c><xref target="sec_result-code-permanent"></xref></c>
</texttable>
</section>
</section>
<section title="Application IDs">
<t>IANA is requested to allocate the following application ID using
the next value from the 7-16777215 range.</t>
<t>Registry:</t>
<texttable align="right" anchor="table_id-codes" suppress-title="true"
title=" Diameter Application ID values">
<ttcol align="left">ID Value</ttcol>
<ttcol align="left">Name</ttcol>
<ttcol align="left">Reference</ttcol>
<c>to be assigned</c>
<c>Diameter NAT Control Application</c>
<c><xref target="sec-dnca"></xref></c>
</texttable>
</section>
</section>
<section anchor="Security" title="Security Considerations">
<t>Similar to what the Diameter QoS application (see <xref
target="I-D.ietf-dime-diameter-qos"></xref>) does for authorization of
QoS reservations, this document describes procedures for authorizing
network address translation related attributes and parameters by an
entity which is non-local to the device performing network address
translation. The security considerations for the Diameter QoS
application (see <xref target="I-D.ietf-dime-diameter-qos"></xref>
section 11) apply in a similar way to the DNCA. Securing the information
exchange between the authorizing entity (the DNCA manager) as well as
the NAT device requires bilateral authentication of the involved
parties, authorization of the involved parties to perform the required
procedures and functions, as well as procedures to ensure integrity and
confidentiality of the information exchange. DNCA makes use of the
capabilities offered by Diameter as well as the underlying transport
protocols to deliver on these requirements (see <xref
target="sec-diameter-messages"></xref> ).</t>
<t>It is assumed that the DNCA agent and DNCA manager are in the same
domain and have a mutual trust set up. Authorization between the DNCA
agent and DNCA manager is beyond the scope of this document.</t>
</section>
<section title="Acknowledgements">
<t>The authors would like to thank Jouni Korhonen, Avi Lior, Chris Metz,
Hannes Tschofenig, 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 (shorted intro section</t>
<t>added support for bindings providing AFT (NAT64)</t>
</list></t>
</section>
</middle>
<!-- *****BACK MATTER ***** -->
<back>
<!-- References split into informative and normative -->
<!-- There are 2 ways to insert reference entries from the citation libraries:
1. define an ENTITY at the top, and use "ampersand character"RFC2629; here (as shown)
2. simply use a PI "less than character"?rfc include="reference.RFC.2119.xml"?> here
(for I-Ds: include="reference.I-D.narten-iana-considerations-rfc2434bis.xml")
Both are cited textually in the same manner: by using xref elements.
If you use the PI option, xml2rfc will, by default, try to find included files in the same
directory as the including file. You can also define the XML_LIBRARY environment variable
with a value containing a set of directories to search. These can be either in the local
filing system or remote ones accessed by http (http://domain/dir/... ).-->
<references title="Normative References">
<!--?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?-->
&RFC2119;
&RFC3588;
&RFC4675;
&RFC5777;
<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>
</references>
<references title="Informative References">
&RFC5624;
&RFC4005;
&I-D.narten-iana-considerations-rfc2434bis;
&I-D.draft-ietf-dime-diameter-qos;
&I-D.draft-nishitani-cgn;
<reference anchor="TS32299">
<front>
<title>3rd Generation Partnership Project; Technical Specification
Group Service and System Aspects; Telecommunication management;
Charging management; "Diameter charging applications", 3GPP TS
32.299 Version 6.3.0.2</title>
<author fullname="3GPP TS 32.299">
<organization></organization>
</author>
<date year="2008" />
</front>
</reference>
</references>
</back>
</rfc>
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