Internet Engineering Task Force F. Brockners
Internet-Draft S. Bhandari
Intended status: Standards Track Cisco
Expires: January 13, 2011 V. Singh
Mavenir Systems
V. Fajardo
Telcordia Technologies
July 12, 2010
Diameter Network Address and Port Translation Control Application
draft-ietf-dime-nat-control-03
Abstract
This document describes the framework, messages, and procedures for
the Diameter Network address and port translation Control Application
(DNCA). The DNCA allows per endpoint control of large scale Network
Address Translators (NATs) and Network Address and Port Translators
(NAPTs), which are added 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 and 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 NAT/
NAPT 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.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on January 13, 2011.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Deployment Framework . . . . . . . . . . . . . . . . . . . . . 7
3.1. Deployment Scenario . . . . . . . . . . . . . . . . . . . 7
3.2. Diameter NAPT Control Application Overview . . . . . . . . 8
3.3. Deployment Scenarios For DNCA . . . . . . . . . . . . . . 9
4. DNCA Session Establishment and Management . . . . . . . . . . 11
4.1. Parties Involved . . . . . . . . . . . . . . . . . . . . . 11
4.2. Session Establishment . . . . . . . . . . . . . . . . . . 11
4.3. Session Re-Authorization . . . . . . . . . . . . . . . . . 13
4.4. Session and Binding Query . . . . . . . . . . . . . . . . 15
4.5. Session Termination . . . . . . . . . . . . . . . . . . . 17
4.6. DNCA Manager and Agent Failures . . . . . . . . . . . . . 18
5. Use Of The Diameter Base Protocol . . . . . . . . . . . . . . 18
5.1. Securing Diameter Messages . . . . . . . . . . . . . . . . 19
5.2. Accounting Functionality . . . . . . . . . . . . . . . . . 19
5.3. Use Of Sessions . . . . . . . . . . . . . . . . . . . . . 19
5.4. Routing Considerations . . . . . . . . . . . . . . . . . . 19
5.5. Advertising Application Support . . . . . . . . . . . . . 19
6. DNCA Commands . . . . . . . . . . . . . . . . . . . . . . . . 20
6.1. NAT-Control Request (NCR) Command . . . . . . . . . . . . 20
6.2. NAT-Control Answer (NCA) Command . . . . . . . . . . . . . 21
7. DNCA AVPs . . . . . . . . . . . . . . . . . . . . . . . . . . 22
7.1. Reused Base Protocol AVPs . . . . . . . . . . . . . . . . 22
7.2. Additional Result-Code AVP Values . . . . . . . . . . . . 23
7.2.1. Success . . . . . . . . . . . . . . . . . . . . . . . 23
7.2.2. Transient Failures . . . . . . . . . . . . . . . . . . 24
7.2.3. Permanent Failures . . . . . . . . . . . . . . . . . . 24
7.3. Reused NASREQ Diameter Application AVPs . . . . . . . . . 25
7.4. Reused from RFC 4675 . . . . . . . . . . . . . . . . . . . 25
7.5. Reused from Diameter QoS Application . . . . . . . . . . . 26
7.6. Reused from ETSI ES 283 034, e4 Diameter Application . . . 26
7.7. DNCA Defined AVPs . . . . . . . . . . . . . . . . . . . . 27
7.7.1. NC-Request-Type AVP . . . . . . . . . . . . . . . . . 27
7.7.2. NAT-Control-Install AVP . . . . . . . . . . . . . . . 28
7.7.3. NAT-Control-Remove AVP . . . . . . . . . . . . . . . . 28
7.7.4. NAT-Control-Definition AVP . . . . . . . . . . . . . . 29
7.7.5. NAT-Internal-Address AVP . . . . . . . . . . . . . . . 29
7.7.6. NAT-External-Address AVP . . . . . . . . . . . . . . . 30
7.7.7. Max-NAT-Bindings . . . . . . . . . . . . . . . . . . . 30
7.7.8. NAT-Control-Binding-Rule AVP . . . . . . . . . . . . . 30
7.7.9. Duplicate-Session-Id AVP . . . . . . . . . . . . . . . 30
8. Accounting Commands . . . . . . . . . . . . . . . . . . . . . 30
8.1. NAT Control Accounting Messages . . . . . . . . . . . . . 31
8.2. NAT Control Accounting AVPs . . . . . . . . . . . . . . . 31
8.2.1. NAT-Control-Record . . . . . . . . . . . . . . . . . . 31
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8.2.2. NAT-Control-Binding-Status . . . . . . . . . . . . . . 31
8.2.3. Current-NAT-Bindings . . . . . . . . . . . . . . . . . 32
9. AVP Occurrence Table . . . . . . . . . . . . . . . . . . . . . 32
9.1. DNCA AVP Table for NAT Control Initial and Update
Requests . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.2. DNCA AVP Table for Session Query request . . . . . . . . . 33
9.3. DNCA AVP Table for NAT Control Terminate requests . . . . 33
9.4. DNCA AVP Table for Accounting Message . . . . . . . . . . 34
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
10.1. Command Codes . . . . . . . . . . . . . . . . . . . . . . 34
10.2. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 35
10.3. AVP Values . . . . . . . . . . . . . . . . . . . . . . . . 35
10.3.1. Result-Code AVP Values . . . . . . . . . . . . . . . . 35
10.4. Application IDs . . . . . . . . . . . . . . . . . . . . . 36
11. Security Considerations . . . . . . . . . . . . . . . . . . . 36
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 37
13. Change History (to be removed prior to publication as an
RFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38
14.1. Normative References . . . . . . . . . . . . . . . . . . . 38
14.2. Informative References . . . . . . . . . . . . . . . . . . 38
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
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1. Introduction
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.
The Diameter Network address and port translation Control Application
(DNCA) offers the following capabilities:
1. Limits or defines the number of NAPT/NAT bindings made available
to an individual subscriber or end point.
2. Supports the allocation of specific NAPT/NAT bindings. Two types
of specific bindings can be distinguished:
* 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.
* 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.
3. Defines the external address pool(s) to be used for allocating an
external IP address: External address pools can either be pre-
assigned at the NAPT/NAT device, or specified within a request.
If pre-assigned address pools are used, a request needs to
include a reference to identify the pool. Otherwise, the request
contains a description of the IP address pool(s) to be used; for
example, list of IP-subnets.
4. Generates reports and accounting records: Reports established
bindings for a particular user. The collected information is
used by accounting systems for statistical purposes.
5. Queries and retrieves details about bindings on demand: This
feature complements the previously mentioned accounting
functionality(see item 4). The query functionality complements
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alternative information query mechanisms, such as SNMP-based
mechanism, if available.
6. 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
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.
2. Conventions
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 [RFC2119].
Abbreviations used in this document:
AAA: Authentication, Authorization, Accounting
DNCA: Diameter Network address and port translation Control
Application
NAPT: Network Address and Port Translation
NAT: Network Address Translation (NAT and NAPT are used in this
document interchangeably)
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
NAS: Network Access Server
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3. Deployment Framework
3.1. Deployment Scenario
Figure 1 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.
+---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+---------+ +---------+ +----------+
| IPv4 | | | | IPv4 |
| Host |----------| NAS |-------------| Internet |
| | | | | |
+---------+ +---------+ +----------+
<-------------------- Public IPv4 ---------------------->
Figure 1: Typical network deployment for internet access
Figure 2 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 sets 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.
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+---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | | | | | IPv4 |
| Host |----| NAS |----| NAT |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Private IPv4 -----------><--- Public IPv4 --->
<-------- Public IPv6 -----------><--- Public IPv4 --->
Figure 2: Access network deployment with LSN
3.2. Diameter NAPT Control Application Overview
The DNCA runs between a DNCA Agent on the NAT device and the DNCA
Manager. DNCA allows per endpoint control and management of 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.
DNCA offers:
o 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.
o Provides per endpoint reporting of the allocated NAT bindings.
o Provides unique identification of an endpoint on NAT device, AAA-
server and NAS, to simplify correlation of accounting data
streams.
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 device.
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3.3. Deployment Scenarios For DNCA
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 Figure 3 ("integrated
deployment") and Figure 4 ("autonomous deployment").
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.
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.
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 device
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.
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+---------+
| |
| AAA |
| |
+---------+
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | (M) | | (A) | | IPv4 |
| Host |----| NAS |----| NAT |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><--- Public IPv4 ---->
<-------- Private IPv4 ----------><--- Public IPv4 ---->
Figure 3: LSN Control deployment: Integrated deployment
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.
+---------+
| (M) |
| AAA |
| |
+---------+
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | | | (A) | | IPv4 |
| Host |----| NAS |----| NAT |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><---- Public IPv4 --->
<-------- Private IPv4 ----------><---- Public IPv4 --->
Figure 4: LSN Control deployment: Autonomous deployment
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4. DNCA Session Establishment and Management
Note that this section forward references some of the commands and
AVPs defined for the DNCA. Please refer to Section 6 and Section 7
for details.
4.1. Parties Involved
Authorization and control models supported by this application
include the following parties:
o DNCA Agent: The DNCA Agent is part of the Large Scale NAT (LSN)
device
o DNCA Manager
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".
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.
4.2. Session Establishment
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.
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. Figure 5 shows the
protocol interaction between the DNCA Manager and the DNCA Agent.
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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:
o 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.
o The maximum number of NAT bindings allowed for an endpoint.
o A description of the external address pool(s) to be used for the
session.
o 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.
In certain cases, the DNCA Agent may not be able to perform the tasks
requested within the NCR. These include the following:
o 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.
o 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.
o 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.
o 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
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within a NCR are completed successfully, or the entire request
fails.
o If DNCA Agent does not have sufficient resources to process a
request, it returns NCA with Result-Code set to RESOURCE_FAILURE.
o 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.
DNCA Manager DNCA Agent
| |
| |
| |
Trigger |
| |
| NCR |
|------------------------------------------>|
| (INITIAL_REQUEST, endpoint classifier, |
| session id, NAT control config data) |
| |
| |
| Create session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |
Figure 5: Initial NAT Control request and session establishment
4.3. Session Re-Authorization
Session re-authorization is performed if the DNCA Manager desires to
change the behavior of the NAT device 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.
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
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NAT-Control Answer (NCA) message with Result-Code set to
DIAMETER_SUCCESS. Figure 6 shows the protocol interaction between
the DNCA Manager and the DNCA Agent.
In certain cases, the DNCA Agent may not be able to perfborm the
tasks requested within the NCR. These include the following:
o 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.
o 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.
o 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.
o 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..
o If DNCA Agent does not have sufficient resources to process a
request, it returns NCA with Result-Code set to RESOURCE_FAILURE.
o 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.
o If a NCR specifies a new binding rule, predefined on the DNCA
Agent, the binding rule overrides any previously defined rules for
the session.
o If Max-NAT-Binding and NAT-Control-Definition AVPs are included in
the NCR along with a reference to a binding rule (a predefined
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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.
DNCA Manager DNCA Agent
| |
| |
| |
Change of session |
attributes |
| |
| NCR |
|------------------------------------------>|
| (UPDATE_REQUEST session id, |
| NAT control config data) |
| |
| |
| Update session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |
Figure 6: NAT Control request for session update
4.4. Session and Binding Query
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.
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.
Figure 7 shows the protocol interaction between the DNCA Manager and
the DNCA Agent.
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.
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1. 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.
2. 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.
DNCA Manager DNCA Agent
| |
| |
| |
DNCA Session Established |
| |
| NCR |
|------------------------------------------>|
| (QUERY_REQUEST) |
| |
| |
| |
| Look up corresponding session
| and associated NAT Bindings
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |
Figure 7: Session Query
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4.5. Session Termination
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. Figure 8 shows the
protocol interaction between the DNCA Manager and the DNCA Agent.
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 NCA with Result-Code set to
DIAMETER_UNKNOWN_SESSION_ID.
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) |
| |
Figure 8: Terminate NAT Control session
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4.6. DNCA Manager and Agent Failures
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.
Example failure cases include the following:
o The DNCA Manager loses session state (e.g. due to a restart). In
this case,
* 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
TERMINATE_REQUEST for the older session, which was lost.
* 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.
o 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.
o 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.
o 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.
5. Use Of The Diameter Base Protocol
The Diameter Base Protocol defined by [RFC3588] applies with the
clarifications listed in the present specification.
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5.1. Securing Diameter Messages
For secure transport of Diameter messages, IPSec MAY be used.
The DNCA Agent MAY verify the identity of the DNCA Manager during the
Capabilities Exchange Request procedure.
The DNCA Agent MAY verify if the DNCA Manager that issues a NCR
command is allowed and it is based on:
o The identity of the DNCA Manager
o The type of NCR Command
o The content of the NCR Command
o Any combination of the above
5.2. Accounting Functionality
Accounting functionality (accounting session state machine, related
command codes and AVPs) is defined in Section 8 below.
5.3. Use Of Sessions
Each DNCA session MUST have a globally unique Session-ID as defined
in [RFC3588], 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
[RFC3588] if it is unable to maintain sessions due to resource
limitation.
5.4. Routing Considerations
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.
5.5. Advertising Application Support
Diameter applications conforming to this specification MUST advertise
support by including the value of TBD in:
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o Auth-Application-Id and Acct-Application-Id of Capabilities-
Exchange-Request (CER)
o Auth-Application-Id of NC-request (NCR), NC-Answer (NCA), Abort-
Session-Request(ASR), Abort-Session-Answer (AAA) messages
o Acct-Application-Id in Accounting-Request (ACR) and Accounting-
Answer (AAA) messages.
6. DNCA Commands
The following commands are used to establish, maintain and clear NAT
bindings.
6.1. NAT-Control Request (NCR) Command
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.
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.
Message Format:
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< 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 ]
6.2. NAT-Control Answer (NCA) Command
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.
Message Format:
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<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 ]
7. DNCA AVPs
7.1. Reused Base Protocol AVPs
AVPs reused from Diameter Base Protocol [RFC3588] are listed below.
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+-------------------+
| 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. |
+-------------------------------------------------------------------+
Figure 9: DIAMETER AVPs used from Diameter base
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.
7.2. Additional Result-Code AVP Values
This section defines new values for the Result-Code AVP which SHALL
be supported by all Diameter implementations that conform to the
present document.
7.2.1. Success
No new Result-Code AVP value is defined within this category.
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7.2.2. Transient Failures
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.
The following new values of the Result-Code AVP are defined:
RESOURCE_FAILURE (TBD)
The DNCA Agent indicates that the binding could not be
installed or a new session could not be created due to resource
shortage.
7.2.3. Permanent Failures
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.
The following new values of the Result-Code AVP are defined:
UNKNOWN_BINDING_RULE_NAME (TBD)
The DNCA Agent indicates that the binding could not be
installed or a new session could not be created due to resource
shortage.
BINDING_FAILURE (TBD)
The DNCA indicates that the requested binding(s) could not be
installed.
MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT (TBD)
The DNCA Agent denies the request because the maximum number of
allowed bindings has been reached for the specified Endpoint
Classifier.
SESSION_EXISTS (TBD)
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.
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INSUFFICIENT_CLASSIFIERS (TBD)
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.
7.3. Reused NASREQ Diameter Application AVPs
The following AVPs are reused from Diameter Network Access Server
Application [RFC4005].
+---------------------+
| 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 | | | | | | | |
+------------------+------+------------|----+-----+----+-----|----+
Figure 10: Reused NASREQ Diameter application AVPs
7.4. Reused from RFC 4675
The following AVPs are reused from "RADIUS Attributes for Virtual LAN
and Priority Support" specification [RFC4675].
+---------------------+
| AVP Flag rules |
+------------------+------+------------|----+-----+----+-----|----+
| | AVP | | | |SHLD| MUST| |
| Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr|
|------------------|------|------------|----+-----+----+-----|----|
| Egress-VLANID | 56 | OctetString| M | P | | V | Y |
+------------------+------+------------|----+-----+----+-----|----+
Figure 11: Reused attributes from RFC 4675
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7.5. Reused from Diameter QoS Application
The following AVPs are reused from the Diameter QoS Application
[I-D.ietf-dime-diameter-qos].
+-------------------+
| 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. |
+-------------------------------------------------------------------+
Figure 12: Reused QoS-attributes
7.6. Reused from ETSI ES 283 034, e4 Diameter Application
The following AVPs are reused from the Diameter e4 Application
[ETSIES283034].
+-------------------+
| 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). |
+-------------------------------------------------------------------+
Figure 13: Reused AVPs from Diameter e4 application
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7.7. DNCA Defined AVPs
The following table describes the new Diameter AVPs used in this
document.
+-------------------+
| 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. |
+-------------------------------------------------------------------+
Figure 14: New Diameter AVPs
7.7.1. NC-Request-Type AVP
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.
The following values are defined:
INITIAL_REQUEST (1)
An Initial Request is used to install binding at the DNCA Agent
on a successful access session setup.
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UPDATE_REQUEST (2)
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.
TERMINATION_REQUEST (3)
Termination Request is used to deactivate and remove all
bindings previously activated on a given access session.
QUERY_REQUEST (4)
Query Request is used to query the DNCA Agent about the
currently installed bindings for an endpoint classifier.
7.7.2. NAT-Control-Install AVP
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.
AVP format:
NAT-Control-Install ::= < AVP Header: TBD >
* [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ]
[ Max-NAT-Bindings]
* [ AVP ]
7.7.3. NAT-Control-Remove AVP
The NAT-Control-Remove AVP (AVP code TBD) is of type Grouped, and it
is used to deactivate or remove NAT bindings.
AVP format:
NAT-Control-Remove ::= < AVP Header: TBD >
* [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ]
* [ AVP ]
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7.7.4. NAT-Control-Definition AVP
The NAT-Control-Definition AVP (AVP code TBD) is of type Grouped, and
it describes a binding.
The NAT-Control-Definition AVP uniquely identifies the binding
between the DNCA Agent and the DNCA Manager.
If both the NAT-Internal-Address and NAT-External-Address AVP(s) are
supplied, it is a pre-defined binding.
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.
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.
AVP format:
NAT-Control-Definition ::= < AVP Header: TBD >
{ NAT-Internal-Address }
[ Protocol ]
[ Direction ]
[ NAT-External-Address ]
[ Session-Id ]
* [ AVP ]
7.7.5. NAT-Internal-Address AVP
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.
AVP format:
NAT-Internal-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ]
[ Framed-IPv6-Prefix ]
[ Port]
* [ AVP ]
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7.7.6. NAT-External-Address AVP
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.
AVP format:
NAT-External-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ]
[ IP-Address-Mask ]
[ Port ]
* [ AVP ]
7.7.7. Max-NAT-Bindings
The Max-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32. It
indicates the maximum number of NAT bindings allowed.
7.7.8. NAT-Control-Binding-Rule AVP
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.
7.7.9. Duplicate-Session-Id AVP
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.
8. Accounting Commands
The DNCA reuses session based accounting as defined in Diameter Base
Protocol,[RFC3588] 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.
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
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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 an NCR
with NC-Request-Type AVP set to TERMINATION_REQUEST.
The function of correlating the multiple bindings used by an endpoint
at any given time is relegated to the post processor.
The DNCA Agent may trigger an interim accounting record when maximum
number of bindings, if received in NCR, is reached.
8.1. NAT Control Accounting Messages
The ACR and ACA messages are reused as defined in Diameter Base
Protocol [RFC3588] 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.
8.2. NAT Control Accounting AVPs
In addition to AVPs for ACR specified in [RFC3588], the DNCA Agent
must add the NAT-Control-Record AVP.
8.2.1. NAT-Control-Record
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.
NAT-Control-Record ::= < AVP Header: TBD >
{ NAT-Control-Definition }
{ NAT-Control-Binding-Status }
[ Event-Timestamp ]
8.2.2. NAT-Control-Binding-Status
The NAT-Control-Binding-Status AVP (AVP code TBD) is of type
enumerated. It indicates the status of the binding - created,
removed, or active.
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The following values are defined:
Created (1)
NAT binding is created.
Active (2)
NAT binding is active.
Removed (3)
NAT binding was removed.
8.2.3. Current-NAT-Bindings
The Current-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32.
It indicates number of NAT bindings active on NAT device.
9. AVP Occurrence Table
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.
The table uses the following symbols:
0 The AVP MUST NOT be present in the message.
0+ Zero or more instances of the AVP MAY be present in the
message.
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.
1 One instance of the AVP MUST be present in the message.
1+ At least one instance of the AVP MUST be present in the
message.
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9.1. DNCA AVP Table for NAT Control Initial and Update Requests
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.
+-------------------+
| 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 |
+-------------------------------------------------------+
9.2. DNCA AVP Table for Session Query request
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.
+-------------------+
| 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 |
+-------------------------------------------------------+
9.3. DNCA AVP Table for NAT Control Terminate requests
The following table lists the DNCA specific AVPs that have to be
present in NCR and NCA with NC-Request-Type set to
TERMINATION_REQUEST.
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+-------------------+
| 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 |
+-------------------------------------------------------+
9.4. DNCA AVP Table for Accounting Message
The following table lists the DNCA specific AVPs, which may or may
not be present in ACR and ACA messages.
+-------------------+
| 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 |
+-------------------------------------------------------+
10. IANA Considerations
This section contains the namespaces that have either been created in
this specification or had their values assigned to existing
namespaces managed by IANA.
10.1. Command Codes
IANA is requested to allocate command code values for the following.
Registry:
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+----------------+---------------------------+-------------+
| Code Value | Name | Reference |
+----------------+---------------------------+-------------+
| to be assigned | NAT-Control-Request (NCR) | Section 6.1 |
| to be assigned | NAT-Control-Answer (NCA) | Section 6.2 |
+----------------+---------------------------+-------------+
Table 1: Command codes
10.2. AVP Codes
IANA is requested to allocate AVP codes for the following AVPs that
are defined in this document.
Registry:
+----------------+----------------------------+---------------+
| Code Value | Name | Reference |
+----------------+----------------------------+---------------+
| to be assigned | NC-Request-Type | Section 7.7.1 |
| to be assigned | NAT-Control-Install | Section 7.7.2 |
| to be assigned | NAT-Control-Remove | Section 7.7.3 |
| to be assigned | NAT-Control-Definition | Section 7.7.4 |
| to be assigned | NAT-Internal-Address | Section 7.7.5 |
| to be assigned | NAT-External-Address | Section 7.7.6 |
| to be assigned | Max-NAT-Bindings | Section 7.7.7 |
| to be assigned | NAT-Control-Binding-Rule | Section 7.7.8 |
| to be assigned | Duplicate-Session-Id | Section 7.7.9 |
| to be assigned | NAT-Control-Record | Section 8.2.1 |
| to be assigned | NAT-Control-Binding-Status | Section 8.2.2 |
| to be assigned | Current-NAT-Bindings | Section 8.2.3 |
+----------------+----------------------------+---------------+
Table 2: AVP codes
10.3. AVP Values
10.3.1. Result-Code AVP Values
Section 7.2 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.
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+-----------+---------------------------------------+---------------+
| Code | Name | Reference |
| Value | | |
+-----------+---------------------------------------+---------------+
| to be | RESOURCE_FAILURE | Section 7.2.2 |
| assigned | | |
| (4xxx) | | |
| to be | UNKNOWN_BINDING_RULE_NAME | Section 7.2.3 |
| assigned | | |
| (5xxx) | | |
| to be | BINDING_FAILURE | Section 7.2.3 |
| assigned | | |
| (5xxx) | | |
| to be | MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT | Section 7.2.3 |
| assigned | | |
| (5xxx) | | |
| to be | SESSION_EXISTS | Section 7.2.3 |
| assigned | | |
| (5xxx) | | |
| to be | INSUFFICIENT_CLASSIFIERS | Section 7.2.3 |
| assigned | | |
| (5xxx) | | |
+-----------+---------------------------------------+---------------+
Table 3: Result Code AVP Values
10.4. Application IDs
IANA is requested to allocate the following application ID using the
next value from the 7-16777215 range.
Registry:
+----------------+----------------------------------+-----------+
| ID Value | Name | Reference |
+----------------+----------------------------------+-----------+
| to be assigned | Diameter NAT Control Application | Section 4 |
+----------------+----------------------------------+-----------+
Table 4: Diameter Application ID values
11. Security Considerations
Similar to the impact of Diameter QoS application (see
[I-D.ietf-dime-diameter-qos]) 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
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device performing NAT. The security considerations for the Diameter
QoS application (see [I-D.ietf-dime-diameter-qos] 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 Section 5.1 ).
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.
12. Acknowledgements
The authors would like to thank Ramya Balakrishna, Jouni Korhonen,
Avi Lior, Chris Metz, Hannes Tschofenig, Greg Weber, and Glen Zorn
for their input on this document.
13. Change History (to be removed prior to publication as an RFC)
Changes from -00 to -01
a. new values for Result-Code AVP used - instead of Experimental-
Result AVP
b. added support for transport specific binding (UDP/TCP)
c. added support for twice-NAT
d. clarified the use of the two different types of query-requests
Changes from -01 to -02
a. Reference to pull mode removed, session initiation event
clarified in section 4.1
b. added Redirect-* AVPs in NCA command
c. Removed reference to Called-Station-Id AVP in NCR command
d. Editorial changes
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e. added support for bindings providing AFT (NAT64)
Changes from -02 to -03
a. Editorial changes
14. References
14.1. Normative References
[ETSIES283034]
ETSI, "Telecommunications and Internet Converged Services
and Protocols for Advanced Networks (TISPAN),Network
Attachment Sub-System (NASS),e4 interface based on the
Diameter protocol.", September 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
[RFC4675] Congdon, P., Sanchez, M., and B. Aboba, "RADIUS Attributes
for Virtual LAN and Priority Support", RFC 4675,
September 2006.
[RFC5777] Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M.,
and A. Lior, "Traffic Classification and Quality of
Service (QoS) Attributes for Diameter", RFC 5777,
February 2010.
14.2. Informative References
[I-D.ietf-dime-diameter-qos]
Sun, D., McCann, P., Tschofenig, H., ZOU), T., Doria, A.,
and G. Zorn, "Diameter Quality of Service Application",
draft-ietf-dime-diameter-qos-14 (work in progress),
February 2010.
[I-D.narten-iana-considerations-rfc2434bis]
Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs",
draft-narten-iana-considerations-rfc2434bis-09 (work in
progress), March 2008.
[I-D.nishitani-cgn]
Nishitani, T., Yamagata, I., Miyakawa, S., Nakagawa, A.,
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and H. Ashida, "Common Functions of Large Scale NAT
(LSN)", draft-nishitani-cgn-03 (work in progress),
November 2009.
[RFC4005] Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
"Diameter Network Access Server Application", RFC 4005,
August 2005.
[RFC5624] Korhonen, J., Tschofenig, H., and E. Davies, "Quality of
Service Parameters for Usage with Diameter", RFC 5624,
August 2009.
[TS32299] "3rd Generation Partnership Project; Technical
Specification Group Service and System Aspects;
Telecommunication management; Charging management;
"Diameter charging applications", 3GPP TS 32.299 Version
9.4.0", 2008.
Authors' Addresses
Frank Brockners
Cisco
Hansaallee 249, 3rd Floor
DUESSELDORF, NORDRHEIN-WESTFALEN 40549
Germany
Email: fbrockne@cisco.com
Shwetha Bhandari
Cisco
Cessna Business Park, Sarjapura Marathalli Outer Ring Road
Bangalore, KARNATAKA 560 087
India
Email: shwethab@cisco.com
Vaneeta Singh
Mavenir Systems
Sharda Towers, 56/13 Nandidurga Road
Bangalore 560046
India
Email: vaneeta@mavenir.com
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Victor Fajardo
Telcordia Technologies
1 Telcordia Drive #1S-222
Piscataway, NJ 08854
USA
Email: vf0213@gmail.com
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