Internet Engineering Task Force F. Brockners
Internet-Draft S. Bhandari
Intended status: Standards Track Cisco
Expires: April 26, 2010 V. Singh
Mavenir Systems
V. Fajardo
Telcordia Technologies
October 23, 2009
Diameter NAT Control Application
draft-ietf-dime-nat-control-01
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Abstract
This document describes the framework, messages, and procedures for
the Diameter NAT Control Application (DNCA), allowing for per-
endpoint control of large scale NAT devices, which are put in place
to cope with IPv4-address space completion. The Diameter NAT Control
Application allows external devices to configure and manage a Large
Scale NAT (LSN) device - expanding the existing Diameter-based AAA
and policy control capabilities with a NAT 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 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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Deployment framework and DNCA capabilities . . . . . . . . . . 6
3.1. Diameter NAT Control Application capabilities . . . . . . 6
3.2. LSN Control Deployment Framework . . . . . . . . . . . . . 7
3.2.1. LSN Deployment scenario . . . . . . . . . . . . . . . 8
3.2.2. Diameter NAT Control Application overview . . . . . . 9
3.2.3. Deployment scenarios for the Diameter NAT Control
Application . . . . . . . . . . . . . . . . . . . . . 9
4. Diameter NAT Control Application Session Establishment and
Management . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1. Parties involved . . . . . . . . . . . . . . . . . . . . . 12
4.2. Session Establishment . . . . . . . . . . . . . . . . . . 12
4.3. Session Re-Authorization . . . . . . . . . . . . . . . . . 14
4.4. Session and Binding Query . . . . . . . . . . . . . . . . 16
4.5. Session Termination . . . . . . . . . . . . . . . . . . . 18
4.6. DNCA Manager/Agent failures . . . . . . . . . . . . . . . 19
5. Use of the DIAMETER base protocol . . . . . . . . . . . . . . 20
5.1. Securing DIAMETER messages . . . . . . . . . . . . . . . . 20
5.2. Accounting functionality . . . . . . . . . . . . . . . . . 21
5.3. Use of sessions . . . . . . . . . . . . . . . . . . . . . 21
5.4. Routing considerations . . . . . . . . . . . . . . . . . . 21
5.5. Advertising Application support . . . . . . . . . . . . . 21
6. Diameter NAT Control Application Commands . . . . . . . . . . 22
6.1. NAT-Control Request (NCR) Command . . . . . . . . . . . . 22
6.2. NAT-Control Answer (NCA) Command . . . . . . . . . . . . . 22
7. Diameter NAT Control Application AVPs . . . . . . . . . . . . 23
7.1. Reused Base Protocol AVPs . . . . . . . . . . . . . . . . 23
7.2. Additional Result-Code AVP values . . . . . . . . . . . . 24
7.2.1. Success . . . . . . . . . . . . . . . . . . . . . . . 24
7.2.2. Transient failures . . . . . . . . . . . . . . . . . . 25
7.2.3. Permanent failures . . . . . . . . . . . . . . . . . . 25
7.3. Reused NASREQ Diameter application AVPs . . . . . . . . . 26
7.4. Reused from RFC 4675 . . . . . . . . . . . . . . . . . . . 26
7.5. Reused from Diameter QoS Application . . . . . . . . . . . 27
7.6. Reused from ETSI ES 283 034, e4 Diameter application . . . 27
7.7. Diameter NAT Control Application Defined AVPs . . . . . . 28
7.7.1. NC-Request-Type AVP . . . . . . . . . . . . . . . . . 28
7.7.2. NAT-Control-Install AVP . . . . . . . . . . . . . . . 29
7.7.3. NAT-Control-Remove AVP . . . . . . . . . . . . . . . . 29
7.7.4. NAT-Control-Definition AVP . . . . . . . . . . . . . . 30
7.7.5. NAT-Internal-Address AVP . . . . . . . . . . . . . . . 30
7.7.6. NAT-External-Address AVP . . . . . . . . . . . . . . . 31
7.7.7. Max-NAT-Bindings . . . . . . . . . . . . . . . . . . . 31
7.7.8. NAT-Control-Binding-Rule AVP . . . . . . . . . . . . . 31
7.7.9. Duplicate-Session-Id AVP . . . . . . . . . . . . . . . 31
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8. Accounting Commands . . . . . . . . . . . . . . . . . . . . . 31
8.1. NAT Control Accounting Messages . . . . . . . . . . . . . 32
8.2. NAT Control Accounting AVPs . . . . . . . . . . . . . . . 32
8.2.1. NAT-Control-Record . . . . . . . . . . . . . . . . . . 32
8.2.2. NAT-Control-Binding-Status . . . . . . . . . . . . . . 32
8.2.3. Current-NAT-Bindings . . . . . . . . . . . . . . . . . 33
9. AVP Occurrence Table . . . . . . . . . . . . . . . . . . . . . 33
9.1. DNCA AVP Table for NAT control initial and update
requests . . . . . . . . . . . . . . . . . . . . . . . . . 34
9.2. DNCA AVP Table for Session Query request . . . . . . . . . 34
9.3. DNCA AVP Table for NAT Control Terminate requests . . . . 34
9.4. DNCA AVP Table for accounting message . . . . . . . . . . 35
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
10.1. Command Codes . . . . . . . . . . . . . . . . . . . . . . 35
10.2. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 36
10.3. AVP Values . . . . . . . . . . . . . . . . . . . . . . . . 36
10.3.1. Result-Code AVP Values . . . . . . . . . . . . . . . . 36
10.4. Application IDs . . . . . . . . . . . . . . . . . . . . . 37
11. Security Considerations . . . . . . . . . . . . . . . . . . . 37
12. Change history (to be removed prior to publication as an
RFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38
13.1. Normative References . . . . . . . . . . . . . . . . . . . 38
13.2. Informative References . . . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
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1. Introduction
With the foreseeable depletion of available IPv4 addresses from the
IANA pool, service providers are starting to consider network designs
which no longer assign unique global IPv4 addresses to their
subscribers. One of the approaches considered, is the deployment of
a provider-operated large scale NAT device between the end-users and
the Internet. Nishitani et al. [I-D.nishitani-cgn] call this NAT
device a "Large Scale NAT (LSN)".
LSNs will be inserted into the existing subscriber access and
aggregation networks which typically provide for per-endpoint service
management and control as well as per-endpoint accounting. Per-
endpoint rules include those which relate to service offerings of the
SP (e.g. access bandwidth, time or volume based access restrictions)
as well as rules which follow legal regulations of the "National
Regulation Authorities (NRA)". The introduction of a LSN impacts the
per-endpoint service offerings as well as the regulatory requirements
and gives rise to new control requirements within the service
provider network: Service providers need to manage the behavior of
the LSN on a per-endpoint basis.
The per-endpoint management capabilities of a LSN comprise, for
example the control of the number of NAT-address-port pairs (often
called "NAT-bindings" or simply "bindings") allocated to a single
endpoint. Given that global IPv4 address-port pairs are becoming a
scarce resource, several service providers intend to restrict the
number of NAT-bindings on a per endpoint basis and thus increase
address utilization efficiency. The number of bindings an endpoint
can consume becomes another parameter within a tiered-service
offering. In addition, the service provider might offer static
bindings to endpoints or pre-allocate external IP-address/port-ranges
to certain endpoints. One of the NRA requirements is that a service
provider needs to provide the identity of a user (which e.g.
translates to the public IP address and ports leveraged by the user
at a given point in time) upon request.
Dynamic per-endpoint management at the LSN requires an associated
interface that has to be tightly integrated with the existing per-
endpoint authentication, authorization, and accounting (AAA)
environment of the service provider.
This document describes the framework, messages and procedures for
the Diameter carrier-grade NAT Control Application (DNCA). The DNCA
interacts with the LSN to coordinate per-endpoint configuration and
management of subscriber traffic traversing the LSN. Use of a
Diameter application allows for simple integration into the existing
AAA environment of a service provider.
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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 are used in this document:
AAA: Authentication, Authorization, Accounting
DNCA: Diameter NAT Control Application
LSN: Large Scale NAT device
NAT: Network Address Translation
NAS: Network Access Server
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
NRA: National Regulatory Authority
3. Deployment framework and DNCA capabilities
3.1. Diameter NAT Control Application capabilities
The Diameter NAT control application offers the following
capabilities:
1. Limit the number of NAT-bindings per endpoint: Define/restrict
the maximum number of NAT-bindings on a per-endpoint basis. This
enables service providers to offer differentiated services based
on the number of bindings and hence optimize the consumption of
IP-address/port-ranges.
2. Request the allocation of specific NAT-bindings: Under normal
operation the LSN would allocate NAT-bindings based on rules and
algorithms local to the LSN. Fixed or pre-defined bindings would
be the exception rather than the rule but are essential for
certain deployment scenarios. Requests for NAT-binding
allocation could happen either at or after initial session
establishment. Two cases could be distinguished:
* Request the allocation of a pre-defined NAT-binding. Both the
internal as well as the external IP-address/port pair are
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specified within the request. Some deployment cases, such as
access to a web-server within a user's home network with IP-
address and port, benefit from statically configured bindings.
* Request the allocation of an external IP-address for a given
internal IP-address and report the allocated external IP-
address back to the requestor. In some deployment scenarios,
the application requires immediate knowledge of the allocated
binding for a given internal IP-address but does not control
the allocation of the external IP-address (e.g. SIP-proxy
server deployments).
3. Define the external address-pool(s) to be used for allocating an
external IP-address. External address-pools can either be pre-
defined on the LSN, or specified within a request. If pre-
defined address-pools are used, a request would just include a
reference (e.g. name) to an already defined address pool on LSN.
Otherwise, the request will contain a description of the IP-
address pool(s) to be used (e.g. list of IP-subnets).
4. Accounting/Reporting: Report established bindings for a
particular user. Apart from statistical and charging purposes,
binding reporting is also required for legal reasons. Most
National Regulatory Authorities (NRA) require that service
providers provide the identity of a user upon request. The
service provider needs to be able to correlate a tuple (public
IP-address, port, time) to a particular user or endpoint.
5. Flexible Information Query: Report details and statistics of
bindings for a single endpoint or a set of endpoints through an
external interface which integrates with the overall per-endpoint
management suite. Hence this information query capability of the
DNCA potentially complements alternative information query
mechanisms such as SNMP-based mechanisms.
6. Global Endpoint ID: The global endpoint ID will allow for common
identification of an endpoint on a LSN as well as other endpoint-
or subscriber-aware devices such as a Network Access Server (NAS)
or an AAA system. 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.
3.2. LSN Control Deployment Framework
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3.2.1. LSN Deployment scenario
Figure 1 shows a typical network deployment for internet access. A
user's IPv4-host gains access to the internet though a Network Access
Server (NAS) which facilitates the authentication of the endpoint and
configures the user's connection according to the authorization and
configuration data received from the AAA-server upon successful
authentication. Public IPv4 addresses are used throughout the
network.
+---------+
| |
| 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 LSN 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 LSN performs
network address translation between private IPv4 addresses and public
IPv4 addresses. If the LSN would be put in place without any
endpoint awareness, the service offerings of the service provider
would be hampered. Provisioning static NAT-bindings for particular
endpoints, using different public IP-address pools for different set
of endpoints (e.g. residential or business customers), as well as
reporting on the allocated bindings on a per-endpoint basis would be
burdensome for a service provider if the LSN would not be aware of
endpoints and allow for per-endpoint control and management which
easily integrates with the already existing per-endpoint management
infrastructure of the service provider.
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+---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | | | | | IPv4 |
| Host |----| NAS |----| LSN |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Private IPv4 -----------><--- Public IPv4 --->
Figure 2: Access network deployment with LSN
3.2.2. Diameter NAT Control Application overview
The Diameter NAT Control Application runs between a Diameter NAT
Control Application Agent on the LSN and the Diameter NAT Control
Application Manager. DNCA allows for per-endpoint control and
management of a LSN. 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 request and answer commands to control the allowed number
of NAT-bindings per endpoint, to request the allocation of specific
bindings for an endpoint, to define the address pool to be used for
an endpoint, to provide per endpoint reporting on the allocated NAT-
bindings, as well as to provide for unique identification of an
endpoint on both LSN, AAA-server and NAS, thus simplifying the
correlation of accounting data streams.
DNCA allows for controlling the behavior of a LSN on a per-endpoint
basis during initial session establishment as well as at later stages
by providing an update procedure for already established sessions.
Using DNCA, per-endpoint NAT-binding information can be retrieved
either using accounting mechanisms or through an explicit session
query to the LSN.
3.2.3. Deployment scenarios for the Diameter NAT Control Application
Deployment dependent, the role of the Diameter NAT Control Manager
can be fulfilled by either the NAS or by an external server such as
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an 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 LSN
from external servers such as the AAA-server as much as possible. It
is suited for environments where minimal changes to the existing AAA
deployment are desired. The NAS, taking the role of the DNCA
manager, is in charge of initiating and managing the session to the
LSN, exchanging LSN specific configuration information as well as
handling reporting and accounting information. The NAS receives
reporting and accounting information from LSN. This way the NAS can
provide for a single accounting record for the user, offloading
external accounting systems from correlating accounting information
received from multiple sources.
An example network attachment for an integrated LSN deployment could
be described as follows: An endpoint connects to the network, with
the NAS being the point of attachment. After successful
authentication, NAS receives endpoint related authorization data from
the AAA-server. A portion of the authorization data applies to per-
endpoint configuration on the NAS itself, another portion describes
authorization and configuration information for NAT control aimed at
the LSN. NAS will initiate a DNCA session to the LSN and send the
relevant authorization and configuration information for the
particular endpoint to the LSN. This could comprise e.g. NAT-
bindings which have to be pre-established for the endpoint, or
management related configuration, such as the maximum number of NAT-
bindings allowed for the endpoint or accounting requirements. The
LSN will send its per-endpoint accounting information to the NAS
which aggregates the accounting information received from the LSN
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 |----| LSN |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Private IPv4 ----------><--- Public IPv4 ---->
Figure 3: LSN Control deployment: Integrated deployment
The autonomous deployment approach decouples user management on NAS
and LSN. The AAA system performing the role of the DNCA manager
manages the connection to the LSN, controls the per-endpoint
configuration, and also receives accounting and reporting information
from LSN. Different from the integrated deployment scenario, the
autonomous deployment scenario does not "hide" the existence of the
LSN 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 LSN.
+---------+
| (M) |
| AAA |
| |
+---------+
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4 | | | | (A) | | IPv4 |
| Host |----| NAS |----| LSN |----| Internet |
| | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Private IPv4 ----------><---- Public IPv4 --->
Figure 4: LSN Control deployment: Autonomous deployment
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4. Diameter NAT Control Application 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 Diameter NAT Control Application (DNCA) agent: The DNCA agent is
part of the Large scale NAT (LSN) device
o Diameter NAT Control Application (DNCA) manager
The current version of the draft assumes that the NAT control
requesting entity is always the DNCA manager. Sessions will always
be initiated, updated, or terminated by the DNCA manager. This mode
of operation is sometimes also referred to as "push mode". Session
initiation by the DNCA agent (sometimes referred to as "pull mode")
will be covered in a future version of this draft.
4.2. Session Establishment
The DNCA manager establishes a session to the DNCA agent to control
the behavior of the NAT device. During session establishment, the
DNCA manager will pass along configuration information to the DNCA
agent. Session configuration information could for example comprise
the maximum number of bindings allowed for the endpoint associated
with this session, a set of pre-defined NAT-bindings to be
established for this endpoint, or a description of the address pool,
external addresses should be allocated from.
The DNCA manager initiates the Diameter NAT Control session to the
DNCA agent. The DNCA manager generates a NAT-Control Request (NCR)
message to the DNCA agent with NC-Request-Type AVP set to
INITIAL_REQUEST. On receipt of the NCR the DNCA agent will setup a
new session for the endpoint associated with the endpoint
classifier(s) contained in the NCR. The DNCA agent notifies the DNCA
manager about successful session setup using a NAT-Control Answer
(NCA) message with Result-Code set to DIAMETER_SUCCESS. Figure 5
shows the protocol interaction between the DNCA manager and the DNCA
agent.
The initial NAT-Control-Request can contain configuration information
for the session which specifies the behavior of the LSN for the
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session. Configuration information which can be included comprises:
o A list of NAT-bindings which should be pre-allocated for the
session (e.g. in case a subscriber requires a fixed external IP-
address/port pair for one of his applications).
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 DNCA agent that will
be applied to the session. Such a predefined binding rule on DNCA
agent may contain, for example, the name of the IP-address pool
that the external IP-addresses should be allocated from, the
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 (i.e. DNCA manager and endpoint identifier match
an already existing session), the DNCA agent will return NCA with
Result-Code set to SESSION_EXISTS, and provides Session-Id of the
existing session in Duplicate-Session-Id AVP.
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 (i.e. DNCA manager and endpoint
identifier match already existing sessions), the DNCA agent will
return a NCA with Result-Code set to Insufficient- Classifiers.
In case a DNCA manager receives a NCA that reports Insufficient-
Classifiers, it may choose to retry establishing a new session
using additional/more specific classifiers.
o If the NCR contains a binding rule not defined on the LSN, the
DNCA agent will return a 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 (i.e. LSN) treats a NCR as an
atomic operation; hence none of the requested bindings will be
established by LSN. Either all requested actions within a NCR are
completed successfully, or the entire request fails.
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o If DNCA agent does not have sufficient resources to process a
request, it will return 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 (i.e. a
predefined template on LSN) 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 LSN 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 NAT-Control Request (NCR) message to the
DNCA agent with NC-Request-Type AVP set to UPDATE_REQUEST upon
receiving a trigger signal. In case the session is updated
successfully, the DNCA agent notifies the DNCA manager about
successful session update using a NAT-Control Answer (NCA) message
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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 perform the tasks
requested within the NCR. These include the following:
o If DNCA agent receives a NCR update/query request for non-existent
session it will set error code in answer, to
DIAMETER_UNKNOWN_SESSION_ID.
o If the NCR contains a binding rule not defined on the LSN, the
DNCA agent will return a 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 will return NCA with Result-Code AVP set
to MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT.
o In case the DNCA agent cannot establish some or all of the
bindings requested in a NCR, but has not yet reached the maximum
number of allowed bindings for the subscriber, it will return a
NCA with Result-Code set to BINDING_FAILURE. The DNCA agent (i.e.
LSN) treats a NCR as an atomic operation; hence none of the
requested bindings will be established by LSN. Either all
requested actions 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 will return a 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
LSN how LSN would cope with a case where the new value is lower
than the actual number of allocated bindings. Typically the LSN
would refrain from enforcing the new limit immediately (i.e.
actively remove bindings) but rather disallow the establishment of
new bindings until the current number of bindings is lower than
the newly established maximum number of allowed bindings.
o If a NCR specifies a new binding rule, predefined on the DNCA
agent, the binding rule will override any previously defined rules
for the session.
o In case Max-NAT-Binding and Nat-Control-Definition are included in
the NCR along with a reference to a binding rule (i.e. a
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predefined template on LSN) 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
| |
| |
| |
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
LSN or discover the session identifier for a particular external IP-
address/port pair.
The DNCA manager initiates a session query by sending a NAT-Control
Request (NCR) message to the DNCA agent with NC-Request-Type AVP set
to QUERY_REQUEST. 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 in to retrieve the
session identifiers, along with the associated bindings, matching a
criteria. This enables the DNCA manager to find out which sessions
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utilize a specific external IP address.
1. Request a list of currently allocated NAT-bindings for a
particular session: The DNCA agent will, on receipt of the NCR,
lookup the session information for the session id contained in
the NCR, and will report all currently active NAT-bindings for
the session using a NAT-Control Answer (NCA) message with Result-
Code set to DIAMETER_SUCCESS. In this case the NCR MUST NOT
contain a NAT-Control-Definition AVP. Each NAT-Binding will be
reported in a NAT-Control-Definition AVP. In case the session id
is unknown to the DNCA agent a DIAMETER_UNKNOWN_SESSION_ID error
is returned.
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 will report the NAT-
bindings and associated session ids corresponding to the external
IP-address/port pairs in a NAT-Control Answer (NCA) message with
Result-Code set to DIAMETER_SUCCESS and the same session id as
the one used in the NCR. In case an external IP-address/port
pair has no associated existing NAT-binding, the NAT-Control-
Definition AVP contained in the reply just contains the NAT-
External-Address AVP.
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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
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 DIAMETER_UNKNOWN_SESSION_ID error.
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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
4.6. DNCA Manager/Agent failures
Disclaimer: This version of the draft does not cover details in case
DNCA manager and DNCA agent go out of sync, which could happen for
example due to DNCA manager or DNCA agent restart, (temporary) loss
of network connectivity etc. Future versions of this draft will
cover failure cases and corresponding behavior of DNCA manager and
DNCA agent in detail.
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 will return an error that contains
Duplicate-Session-Id AVP to report Session-Id of existing
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session. The DNCA manager may then send an explicit
TERMINATE_REQUEST for the older session that was lost.
* the DNCA manager may receive accounting records for a session
that does not exist. The DNCA manager will send an accounting
answer with error-code set to DIAMETER_UNKNOWN_SESSION_ID. On
receipt of which the DNCA agent clears the session and removes
the associated session state.
o The DNCA agent loses session state. In such a case, the DNCA
agent could receive a NCR with NC-Request-Type AVP set to
UPDATE_REQUEST for a non-existent session. The DNCA agent will
return NCA with error code set to DIAMETER_UNKNOWN_SESSION_ID.
State recovery procedures of the DNCA agent will be covered in a
future version of this document.
o The DNCA manager is unreachable (as e.g. detected by Diameter
watchdog) or down and accounting requests from the DNCA agent fail
to get a response. The current version of the draft does not
specify procedures for DNCA agent session state clean up or
recovery. The mechanism to ensure that a DNCA manager no longer
has associated state for a session being cleared at the DNCA agent
is beyond the scope of this document.
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 could, for
example, choose to terminate the access session to the endpoint.
5. Use of the DIAMETER base protocol
The DIAMETER Base Protocol defined by [RFC3588] shall apply, with the
clarifications listed in the present specification.
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 to do so, based on:
o The Identity of the DNCA Manager
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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 (see also capabilities Section 3.1). The DNCA agent and
DNCA manager maintain state associated with the Session-Id. This
globally unique Session-Id is used for updating, accounting for and
terminating the session. DNCA session MUST NOT have more than one
outstanding request at any given instant. The DNCA agent sends an
Abort-Session-Request as defined in [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 address/name 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:
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.
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6. Diameter NAT Control Application Commands
The following commands are used to establish, maintain and clear LSN
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.
Message Format:
< 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-Interface-Id ]
[ EGRESS-VLANID]
[ NAS-Port-ID]
[ Address-Realm ]
[ Called-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 ]
* [ AVP ]
7. Diameter NAT Control Application 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
Result-Code AVP values that fall within the permanent failures
category are used to inform the peer that the request failed, and
should not be attempted again. The request may be able to be
satisfied in the future.
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
init request.
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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 |
| Called-Station-Id| 30 | 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 | | | | | | | |
+------------------+------+------------|----+-----+----+-----|----+
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. Diameter NAT Control Application Defined AVPs
The following table describes the new Diameter AVPs used in the
present document, their AVP Code values, types, possible flag values
and whether the AVP may or not be encrypted.
+-------------------+
| 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)
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An Initial Request is used to install binding at the DNCA agent
on a successful access session setup.
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 ]
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* [ AVP ]
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 which the
binding is created. Exactly zero or one Protocol AVP may be
contained within NAT-Control-Definition AVP. If the Protocol AVP is
omitted and if both internal and external address are specified then
the binding reserves the addresses for all transport protocols.
The Direction AVP is of type Enumerated and specifies in which
direction to apply the binding. The values of the enumeration
applicable in this context are: "IN","OUT". If Direction AVP is OUT
or absent NAT-Internal-Address refers to the address of the
subscriber device that needs to be translated. If Direction AVP is
"IN" NAT-Internal-Address is the destination address that has to be
translated.
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, and
it describes the internal IP address and port for a binding.
AVP format:
NAT-Internal-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ]
[ 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, and 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 is of type
OctetString, and it defines a name for a policy template that will be
predefined at LSN. Details on the contents and structure of the
template as well as how it would be configured are outside the scope
of this document. The policy to which this AVP refers to may contain
NAT Bindings, address pool for external address allocation of NAT
binding, maximum allowed NAT bindings etc.
7.7.9. Duplicate-Session-Id AVP
The Duplicate-Session-Id AVP (AVP Code TBD) is of is of type
UTF8String. It is used to report error and contains the Session-Id
of an existing session.
8. Accounting Commands
The Diameter NAT Control Application reuses session based accounting
as defined in Diameter Base Protocol [RFC3588] to report the bindings
used per endpoint. This reporting is achieved by sending Diameter
Accounting Requests (ACR) [Start, Interim and Stop] from the DNCA
agent to DNCA manager.
The DNCA agent sends an ACR Start on receiving an NCR with NC-
Request-Type AVP set to INITIAL_REQUEST received for a session, or on
creation of the first binding for a session requested in an earlier
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NCR. The DNCA may send ACR Interim updates, if required, either due
to a change in bindings resulting from an NCR with NC-Request-Type
AVP set to UPDATE_REQUEST, or periodically as specified in Acct-
Interim-Interval by DNCA Manager or when it creates/tears down
bindings. An ACR Stop is sent by the DNCA agent on receiving an NCR
with NC-Request-Type AVP set to TERMINATION_REQUEST.
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 the CDF. ACR will contain one or more
optional NAT-Control-Record AVP to report the bindings. The DNCA
agent indicates the number of the currently allocated NAT bindings to
the DNCA manager using the Current-NAT-Bindings AVP. This number
needs to match the number of bindings identified as active within the
NAT-Control-Record AVP.
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, and it
describes a binding and its status. Event-Timestamp indicates the
time at which binding was created if NAT-Control-Binding-Status is
set to Created, or time at which the binding was removed if NAT-
Control-Binding-Status is set to removed. If the NAT-Control-
Binding-Status is active Event-Timestamp need not be present, if
present it indicates that binding is active at the mentioned time.
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 and it describes whether the binding being reported was
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created or removed or simply indicates that it is active.
The following values are defined:
Created (1)
Indicates that NAT binding is created.
Active (2)
Indicates that NAT binding is active.
Removed (3)
Indicates that the NAT binding was removed.
8.2.3. Current-NAT-Bindings
The Current-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32,
and it indicates number of NAT bindings active on LSN.
9. AVP Occurrence Table
The following sections presents the AVPs defined in this document and
specifies in which Diameter messages they MAY be present. Note that
AVPs that can only be present within a Grouped AVP are not
represented in this table.
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 presents which NAT control application specific
AVPs are to be present in NCR/NCA with NC-Request-Type set to
INITIAL_REQUEST or UPDATE_REQUEST.
+-------------------+
| 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 presents which NAT control application specific
AVPs are to be present in NCR/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 presents which NAT control application specific
AVPs are to be present in NCR/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
Following table presents which NAT control application specific AVPs
May or May Not be present in ACR/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 failures and permanent failures. IANA is requested to
allocate the corresponding values from the ranges for transient
(4xxx) and permanent (5xxx) failures.
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+-----------+---------------------------------------+---------------+
| Code | Name | Reference |
| Value | | |
+-----------+---------------------------------------+---------------+
| to be | RESOURCE_FAILURE | Section 7.2.2 |
| assigned | | |
| to be | UNKNOWN_BINDING_RULE_NAME | Section 7.2.3 |
| assigned | | |
| to be | BINDING_FAILURE | Section 7.2.3 |
| assigned | | |
| to be | MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT | Section 7.2.3 |
| assigned | | |
| to be | SESSION_EXISTS | Section 7.2.3 |
| assigned | | |
| to be | INSUFFICIENT_CLASSIFIERS | Section 7.2.3 |
| assigned | | |
+-----------+---------------------------------------+---------------+
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 what the Diameter QoS application (see
[I-D.ietf-dime-diameter-qos]) does for authorization of QoS
reservations, this document describes procedures for authorizing
network address translation related attributes and parameters by an
entity which is non-local to the device performing network address
translation. The security considerations for the Diameter QoS
application (see [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) as well as the NAT device
requires bilateral authentication of the involved parties,
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authorization of the involved parties to perform the required
procedures and functions, as well as procedures to ensure integrity
and confidentiality of the information exchange. DNCA makes use of
the capabilities offered by Diameter as well as the underlying
transport protocols to deliver on these requirements (see
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. 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
13. References
13.1. 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.
[I-D.ietf-dime-qos-attributes]
Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M.,
and A. Lior, "Quality of Service Attributes for Diameter",
draft-ietf-dime-qos-attributes-13 (work in progress),
July 2009.
[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.
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[RFC4675] Congdon, P., Sanchez, M., and B. Aboba, "RADIUS Attributes
for Virtual LAN and Priority Support", RFC 4675,
September 2006.
13.2. 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-11 (work in progress),
August 2009.
[I-D.ietf-dime-qos-parameters]
Korhonen, J., Tschofenig, H., and E. Davies, "Quality of
Service Parameters for Usage with Diameter",
draft-ietf-dime-qos-parameters-11 (work in progress),
May 2009.
[I-D.nishitani-cgn]
Nishitani, T., Miyakawa, S., Nakagawa, A., and H. Ashida,
"Common Functions of Large Scale NAT (LSN)",
draft-nishitani-cgn-02 (work in progress), June 2009.
[RFC4005] Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
"Diameter Network Access Server Application", RFC 4005,
August 2005.
[TS32299] "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", 2008.
Authors' Addresses
Frank Brockners
Cisco
Hansaallee 249, 3rd Floor
DUESSELDORF, NORDRHEIN-WESTFALEN 40549
Germany
Email: fbrockne@cisco.com
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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
Victor Fajardo
Telcordia Technologies
1 Telcordia Drive #1S-222
Piscataway, NJ 08854
USA
Email: vfajardo@research.telcordia.com
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