One document matched: draft-ietf-dime-nat-control-04.xml
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<rfc category="std" docName="draft-ietf-dime-nat-control-04" 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 day="16" month="October" 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.
This Diameter application allows per endpoint control of large scale
Network Address Translators and Network Address and Port Translators,
which are added to cope with IPv4-address space completion. 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 large scale 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 large scale
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) 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 NAT 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 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 subscriber or end point.</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. In 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, 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, list
of IP-subnets. Such External address pools can be used to select
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). The query functionality complements
alternative information query mechanisms, such as SNMP-based
mechanism, if available.</t>
<t>Identifies a subscriber or endpoint on multiple network devices
(NAPT or 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 DNCA 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 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 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>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-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 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 hampered. Provisioning static NAT bindings for
particular endpoints, using different public IP address pools for
different set of endpoints; for example, residential or business
customers, and reporting allocated bindings on a per endpoint basis is
burdensome for a service provider if the NAT device is not aware of
endpoints and allows 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 |
| IPv6 |----| NAS |----| NAT |----| Internet |
| Host | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Private IPv4 -----------><--- Public IPv4 --->
<-------- Public IPv6 -----------><--- Public IPv4 --->
]]></artwork>
</figure>
</section>
<section title="Diameter NAPT Control Application Overview">
<t>The DNCA runs between a DNCA Agent on the NAT and the DNCA Manager.
DNCA allows per endpoint control and management of NAT. 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>The role of the Diameter NAT Control Manager can be fulfilled by
either the NAS or by an external server, such as 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. As DNCA Manager the NAS,
initiates and manages session 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 provides a
single accounting record for the user. This reduces the usage of an
external accounting system for correlating the information received
from multiple sources.</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,
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. 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 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 or accounting requirements. The NAT device
sends its per endpoint accounting information to the NAS, which
aggregates the accounting information received form the NAT device
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 |
| IPv6 |----| NAS |----| NAT |----| Internet |
| Host | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- 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 |
| IPv6 |----| NAS |----| NAT |----| Internet |
| Host | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- 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 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>DNCA agent: The DNCA agent is part of the NAT device</t>
<t>DNCA Manager</t>
</list></t>
<t>The NAT control requesting entity is always the DNCA Manager. The
DNCA Manager always initiates, updates, or terminates the sessions.
This mode of operation is sometimes also referred to as "push
mode".</t>
<t>The DNCA Manager can be NAS or AAA-server. The DNCA Manager
initiates a session with the DNCA agent when it learns about the
subscriber. The 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 a subscriber with respect to his IP packets.</t>
</section>
<section title="Session Establishment">
<t>The DNCA Manager establishes a session with the DNCA agent to
control the behavior of the NAT device. During session establishment,
the DNCA Manager passes along configuration information to the DNCA
agent. 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, external addresses to
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 NCR the DNCA Agent sets up 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 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 subscriber requires a fixed
external IP- address/port pair for one of the 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 the DNCA Agent,
which is applied to the session. Such a predefined binding rule on
the 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; that is, DNCA Manager and endpoint identifier
match an already existing session, the DNCA Agent returns NCA with
Result-Code set to SESSION_EXISTS, and provides the 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; that is, DNCA Manager and
endpoint identifier match already existing sessions, the DNCA
Agent returns a NCA with Result-Code set to
Insufficient-Classifiers. In case a DNCA Manager receives 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 Agent returns 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, that is 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 DNCA Agent does not have sufficient resources to process a
request, it returns 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[ 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 NC 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 perfborm the
tasks requested within the NCR. These include the following: <list
style="symbols">
<t>If DNCA Agent 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, the DNCA Agent returns 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 returns NCA with Result-Code AVP
set to MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT.</t>
<t>If 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 returns a NCA with
Result-Code set to BINDING_FAILURE. The DNCA Agent (i.e., NAT
device) treats a NCR as an atomic operation. Hence none of the
requested bindings will be established by NAT device. Either all
requested actions within a NCR are either successful or failed
completely..</t>
<t>If DNCA Agent does not have sufficient resources to process a
request, it returns 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 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 DNCA
agent, the binding rule overrides any previously defined rules 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 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></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 device 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 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 to retrieve the
session identifiers, along with the associated bindings, matching a
criteria. This enables the DNCA Manager to find the 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: The DNCA Agent on receiving NCR, looks up
session information for the session ID contained in the NCR, and
reports all currently active NAT bindings for the session using
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 Agent 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 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 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 is 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[ 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 Session Terminate Request (STR)
message to the DNCA Agent upon receiving a trigger signal. The source
of the trigger signal is outside the scope of this document. The DNCA
Agent sends accounting stop record reporting all the bindings and
notifies the DNCA Manager 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 DNCA Manager and the DNCA
Agent.</t>
<t>If a DNCA Agent receives STR from a DNCA Manager and fails to find
a matching session, the DNCA Agent returns STA with Result-Code set to
DIAMETER_UNKNOWN_SESSION_ID.</t>
<figure anchor="fig-session-terminate"
title="Terminate NAT Control session">
<artwork><![CDATA[
DNCA Manager DNCA Agent
| |
| |
Trigger |
| |
| STR |
|------------------------------------------->|
| (session id) |
| |
| |
| Remove NAT bindings
| of session
| |
| |
| Send accounting stop |
|<-------------------------------------------|
| for all session bindings |
| |
| Terminate Session /
| Remove session state
| |
| |
| |
| STA |
|<-------------------------------------------|
| (Result-Code) |
| |]]></artwork>
</figure>
</section>
<section title="DNCA Manager and Agent Failures">
<t>This document does not cover details in case DNCA Manager and DNCA
Agent are out of sync. This happens when the DNCA Manager or DNCA
Agent restart, (temporary) loss of network connectivity etc. The DNCA
relies 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 returns an error that contains
Duplicate-Session-Id AVP to report the Session-ID of existing
session. The DNCA Manager may send an explicit Sesstion
Terminate Request(STR) for the older session, which was
lost.</t>
<t>The DNCA Manager may receive accounting records for a
session that does not exist. The DNCA Manager sends an
accounting answer with Result-Code set to
DIAMETER_UNKNOWN_SESSION_ID. On receiving this, 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 may receive a NCR with NC-Request-Type AVP set to
UPDATE_REQUEST for a non-existent session. The DNCA Agent returns
NCA with Result-Code set to DIAMETER_UNKNOWN_SESSION_ID.</t>
<t>The DNCA Manager is unreachable, for example detected by
Diameter watchdog, or down and accounting request from the DNCA
Agent fails to get a response. The mechanism to ensure that a DNCA
Manager no longer has associated state for a session being cleared
by a 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 can
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>
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, 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 and it is 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, and terminating the session. The
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 (ASA)
messages</t>
<t>Acct-Application-Id in Accounting-Request (ACR) and
Accounting-Answer (ACA) messages.</t>
</list></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 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 ]
* [ 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 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. DNCA Agent and Manager
are stateful and the state machine maintained is similar to the stateful
Client and Server authorization state machine described in RFC3588. 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 Manager is unable to send command NCR to the desired destination.
This could be due to the peer being down, or due to the peer sending
back a 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 Agent was not
able to honor corresponding NCR. This can happen due to any of the
transient and permanent error at DNCA Agent 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 Manager:</t>
<figure>
<artwork><![CDATA[ MANAGER
State Event Action New State
-------------------------------------------------------------
Idle New Host 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 Agent 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
client will comply with with
request to end the session Result-Code
= SUCCESS,
Send STR.
Open ASR Received, Send ASA Open
client will not comply with with
request to end the session 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 Agent:</t>
<figure>
<artwork><![CDATA[ AGENT
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 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>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 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 initializationrequest.</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 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 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 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>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 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 address are specified then the binding
reserves the 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,
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.
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. External IP address specified in this attribute can be
reused for multiple subscribers 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.</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 will be
predefined at NAT. 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,
address pool for external address allocation of NAT binding, and
maximum allowed NAT bindings. Such policy template can be reused by
specifying same NAT-Control-Binding-Rule AVP in corresponding
NAT-Control-Install AVPs of multiple subscribers.</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 error 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 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 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 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 a NCR with NC-Request-Type AVP set to
UPDATE_REQUEST, or periodically as specified in Acct-Interim-Interval by
the DNCA Manager, or when it creates or tears down bindings. An ACR Stop
is sent by the DNCA Agent 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 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 DNCA Manager. The DNCA
Application ID is used in the accounting commands. ACR contains one or
more optional NAT-Control-Record AVP to report the bindings. The DNCA
Agent indicates the number of 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. 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 the 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 |
|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 lists the 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+ |
|NAT-Control-Record 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 the 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 |
+-------------------------------------------------------+
|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 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 the impact of Diameter QoS application (see <xref
target="I-D.ietf-dime-diameter-qos"></xref>) on authorization of QoS
reservations, this document describes procedures for authorizing NAT
related attributes and parameters by an entity, which is non-local to
the device performing NAT. 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) and the NAT
device requires bilateral authentication of the involved parties,
authorization of the involved parties to perform the required procedures
and functions, and procedures to ensure integrity and confidentiality of
the information exchange. The 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> ).</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</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 Lastcall 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></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">
&RFC4005;
&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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