draft-ietf-dime-nat-control-09.txt   draft-ietf-dime-nat-control-10.txt 
Internet Engineering Task Force F. Brockners Internet Engineering Task Force F. Brockners
Internet-Draft S. Bhandari Internet-Draft S. Bhandari
Intended status: Standards Track Cisco Intended status: Standards Track Cisco
Expires: January 11, 2012 V. Singh Expires: March 5, 2012 V. Singh
V. Fajardo V. Fajardo
Telcordia Technologies Telcordia Technologies
July 10, 2011 September 2, 2011
Diameter Network Address and Port Translation Control Application Diameter Network Address and Port Translation Control Application
draft-ietf-dime-nat-control-09 draft-ietf-dime-nat-control-10
Abstract Abstract
This document describes the framework, messages, and procedures for This document describes the framework, messages, and procedures for
the Diameter Network address and port translation Control the Diameter Network address and port translation Control
Application. This Diameter application allows per endpoint control Application. This Diameter application allows per endpoint control
of Network Address Translators and Network Address and Port of Network Address Translators and Network Address and Port
Translators, which are added to networks to cope with IPv4-address Translators, which are added to networks to cope with IPv4-address
space depletion. This Diameter application allows external devices space depletion. This Diameter application allows external devices
to configure and manage a Network Address Translator device - to configure and manage a Network Address Translator device -
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 11, 2012. This Internet-Draft will expire on March 5, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Deployment Framework . . . . . . . . . . . . . . . . . . . . . 7 3. Deployment Framework . . . . . . . . . . . . . . . . . . . . . 8
3.1. Deployment Scenario . . . . . . . . . . . . . . . . . . . 7 3.1. Deployment Scenario . . . . . . . . . . . . . . . . . . . 8
3.2. Diameter NAPT Control Application Overview . . . . . . . . 9 3.2. Diameter NAPT Control Application Overview . . . . . . . . 10
3.3. Deployment Scenarios For DNCA . . . . . . . . . . . . . . 10 3.3. Deployment Scenarios For DNCA . . . . . . . . . . . . . . 10
4. DNCA Session Establishment and Management . . . . . . . . . . 12 4. DNCA Session Establishment and Management . . . . . . . . . . 13
4.1. Session Establishment . . . . . . . . . . . . . . . . . . 12 4.1. Session Establishment . . . . . . . . . . . . . . . . . . 13
4.2. Session Re-Authorization . . . . . . . . . . . . . . . . . 14 4.2. Session Re-Authorization . . . . . . . . . . . . . . . . . 16
4.3. Session and Binding Query . . . . . . . . . . . . . . . . 17 4.3. Session and Binding Query . . . . . . . . . . . . . . . . 18
4.4. Session Termination . . . . . . . . . . . . . . . . . . . 18 4.4. Session Termination . . . . . . . . . . . . . . . . . . . 20
4.5. Session Abort . . . . . . . . . . . . . . . . . . . . . . 19 4.5. Session Abort . . . . . . . . . . . . . . . . . . . . . . 21
4.6. Failure cases of the DNCA Diameter peers . . . . . . . . . 20 4.6. Failure cases of the DNCA Diameter peers . . . . . . . . . 22
5. Use Of The Diameter Base Protocol . . . . . . . . . . . . . . 21 5. Use of the Diameter Base Protocol . . . . . . . . . . . . . . 23
5.1. Securing Diameter Messages . . . . . . . . . . . . . . . . 21 5.1. Securing Diameter Messages . . . . . . . . . . . . . . . . 23
5.2. Accounting Functionality . . . . . . . . . . . . . . . . . 22 5.2. Accounting Functionality . . . . . . . . . . . . . . . . . 24
5.3. Use Of Sessions . . . . . . . . . . . . . . . . . . . . . 22 5.3. Use of Sessions . . . . . . . . . . . . . . . . . . . . . 24
5.4. Routing Considerations . . . . . . . . . . . . . . . . . . 22 5.4. Routing Considerations . . . . . . . . . . . . . . . . . . 24
5.5. Advertising Application Support . . . . . . . . . . . . . 22 5.5. Advertising Application Support . . . . . . . . . . . . . 24
6. DNCA Commands . . . . . . . . . . . . . . . . . . . . . . . . 22 6. DNCA Commands . . . . . . . . . . . . . . . . . . . . . . . . 24
6.1. NAT-Control Request (NCR) Command . . . . . . . . . . . . 22 6.1. NAT-Control Request (NCR) Command . . . . . . . . . . . . 24
6.2. NAT-Control Answer (NCA) Command . . . . . . . . . . . . . 23 6.2. NAT-Control Answer (NCA) Command . . . . . . . . . . . . . 25
7. NAT Control Application Session State Machine . . . . . . . . 24 7. NAT Control Application Session State Machine . . . . . . . . 26
8. DNCA AVPs . . . . . . . . . . . . . . . . . . . . . . . . . . 27 8. DNCA AVPs . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.1. Reused Base Protocol AVPs . . . . . . . . . . . . . . . . 27 8.1. Reused Base Protocol AVPs . . . . . . . . . . . . . . . . 30
8.2. Additional Result-Code AVP Values . . . . . . . . . . . . 28 8.2. Additional Result-Code AVP Values . . . . . . . . . . . . 30
8.2.1. Success . . . . . . . . . . . . . . . . . . . . . . . 28 8.2.1. Success . . . . . . . . . . . . . . . . . . . . . . . 30
8.2.2. Transient Failures . . . . . . . . . . . . . . . . . . 28 8.2.2. Transient Failures . . . . . . . . . . . . . . . . . . 31
8.2.3. Permanent Failures . . . . . . . . . . . . . . . . . . 29 8.2.3. Permanent Failures . . . . . . . . . . . . . . . . . . 31
8.3. Reused NASREQ Diameter Application AVPs . . . . . . . . . 30 8.3. Reused NASREQ Diameter Application AVPs . . . . . . . . . 32
8.4. Reused AVPs from RFC 4675 . . . . . . . . . . . . . . . . 30 8.4. Reused AVPs from RFC 4675 . . . . . . . . . . . . . . . . 32
8.5. Reused AVPs from Diameter QoS Application . . . . . . . . 31 8.5. Reused AVPs from Diameter QoS Application . . . . . . . . 33
8.6. Reused AVPs from ETSI ES 283 034, e4 Diameter 8.6. Reused AVPs from ETSI ES 283 034, e4 Diameter
Application . . . . . . . . . . . . . . . . . . . . . . . 31 Application . . . . . . . . . . . . . . . . . . . . . . . 33
8.7. DNCA Defined AVPs . . . . . . . . . . . . . . . . . . . . 32 8.7. DNCA Defined AVPs . . . . . . . . . . . . . . . . . . . . 34
8.7.1. NC-Request-Type AVP . . . . . . . . . . . . . . . . . 32 8.7.1. NC-Request-Type AVP . . . . . . . . . . . . . . . . . 35
8.7.2. NAT-Control-Install AVP . . . . . . . . . . . . . . . 33 8.7.2. NAT-Control-Install AVP . . . . . . . . . . . . . . . 36
8.7.3. NAT-Control-Remove AVP . . . . . . . . . . . . . . . . 33 8.7.3. NAT-Control-Remove AVP . . . . . . . . . . . . . . . . 36
8.7.4. NAT-Control-Definition AVP . . . . . . . . . . . . . . 33 8.7.4. NAT-Control-Definition AVP . . . . . . . . . . . . . . 36
8.7.5. NAT-Internal-Address AVP . . . . . . . . . . . . . . . 34 8.7.5. NAT-Internal-Address AVP . . . . . . . . . . . . . . . 37
8.7.6. NAT-External-Address AVP . . . . . . . . . . . . . . . 34 8.7.6. NAT-External-Address AVP . . . . . . . . . . . . . . . 37
8.7.7. Max-NAT-Bindings . . . . . . . . . . . . . . . . . . . 35 8.7.7. Max-NAT-Bindings . . . . . . . . . . . . . . . . . . . 38
8.7.8. NAT-Control-Binding-Rule AVP . . . . . . . . . . . . . 35 8.7.8. NAT-Control-Binding-Template AVP . . . . . . . . . . . 38
8.7.9. Duplicate-Session-Id AVP . . . . . . . . . . . . . . . 35 8.7.9. Duplicate-Session-Id AVP . . . . . . . . . . . . . . . 38
9. Accounting Commands . . . . . . . . . . . . . . . . . . . . . 35 8.7.10. NAT-External-Port-Style AVP . . . . . . . . . . . . . 38
9.1. NAT Control Accounting Messages . . . . . . . . . . . . . 36 9. Accounting Commands . . . . . . . . . . . . . . . . . . . . . 39
9.2. NAT Control Accounting AVPs . . . . . . . . . . . . . . . 36 9.1. NAT Control Accounting Messages . . . . . . . . . . . . . 39
9.2.1. NAT-Control-Record . . . . . . . . . . . . . . . . . . 36 9.2. NAT Control Accounting AVPs . . . . . . . . . . . . . . . 40
9.2.2. NAT-Control-Binding-Status . . . . . . . . . . . . . . 36 9.2.1. NAT-Control-Record . . . . . . . . . . . . . . . . . . 40
9.2.3. Current-NAT-Bindings . . . . . . . . . . . . . . . . . 37 9.2.2. NAT-Control-Binding-Status . . . . . . . . . . . . . . 40
10. AVP Occurrence Table . . . . . . . . . . . . . . . . . . . . . 37 9.2.3. Current-NAT-Bindings . . . . . . . . . . . . . . . . . 40
10. AVP Occurrence Table . . . . . . . . . . . . . . . . . . . . . 41
10.1. DNCA AVP Table for NAT Control Initial and Update 10.1. DNCA AVP Table for NAT Control Initial and Update
Requests . . . . . . . . . . . . . . . . . . . . . . . . . 37 Requests . . . . . . . . . . . . . . . . . . . . . . . . . 41
10.2. DNCA AVP Table for Session Query request . . . . . . . . . 38 10.2. DNCA AVP Table for Session Query request . . . . . . . . . 42
10.3. DNCA AVP Table for Accounting Message . . . . . . . . . . 38 10.3. DNCA AVP Table for Accounting Message . . . . . . . . . . 42
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 43
11.1. Application Identifier . . . . . . . . . . . . . . . . . . 39 11.1. Application Identifier . . . . . . . . . . . . . . . . . . 43
11.2. Command Codes . . . . . . . . . . . . . . . . . . . . . . 39 11.2. Command Codes . . . . . . . . . . . . . . . . . . . . . . 43
11.3. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 39 11.3. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 43
11.4. Result-Code AVP Values . . . . . . . . . . . . . . . . . . 39 11.4. Result-Code AVP Values . . . . . . . . . . . . . . . . . . 43
11.5. NC-Request-Type AVP . . . . . . . . . . . . . . . . . . . 39 11.5. NC-Request-Type AVP . . . . . . . . . . . . . . . . . . . 43
11.6. NAT-Control-Binding-Status AVP . . . . . . . . . . . . . . 39 11.6. NAT-External-Port-Style AVP . . . . . . . . . . . . . . . 43
12. Security Considerations . . . . . . . . . . . . . . . . . . . 40 11.7. NAT-Control-Binding-Status AVP . . . . . . . . . . . . . . 44
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 41 12. Security Considerations . . . . . . . . . . . . . . . . . . . 44
14. Change History (to be removed prior to publication as an 13. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
RFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 13.1. DNCA Session Establishment Example . . . . . . . . . . . . 46
15. Normative References . . . . . . . . . . . . . . . . . . . . . 43 13.2. DNCA Session Update with Port Style Example . . . . . . . 49
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 44 13.3. DNCA Session Query Example . . . . . . . . . . . . . . . . 50
13.4. DNCA Session Termination Example . . . . . . . . . . . . . 51
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 54
15. Change History (to be removed prior to publication as an
RFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 57
16.1. Normative References . . . . . . . . . . . . . . . . . . . 57
16.2. Informative References . . . . . . . . . . . . . . . . . . 57
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 58
1. Introduction 1. Introduction
Internet service providers have started to deploy Network Address Internet service providers deploy Network Address Translators (NATs)
Translators (NATs) and Network Address and Port Translators (NAPTs) and Network Address and Port Translators (NAPTs) [RFC3022] in their
in their networks to deal with the depletion of available public IPv4 networks. A key motivation for doing so is the depletion of
addresses. This document defines a Diameter application allowing available public IPv4 addresses. This document defines a Diameter
providers to control the behavior of these NAT and NAPT devices. The application allowing providers to control the behavior of NAT and
use of a Diameter application allows for simple integration into the NAPT devices that implement IPv4-to-IPv4 network address and port
existing Authentication, Authorization and Accounting (AAA) translation [RFC2663] as well as stateful IPv6-to-IPv4 address family
environment of a provider. translation translation as defined in [RFC2663], [RFC6145], and
[RFC6146]. The use of a Diameter application allows for simple
integration into the existing Authentication, Authorization and
Accounting (AAA) environment of a provider.
The Diameter Network address and port translation Control Application The Diameter Network address and port translation Control Application
(DNCA) offers the following capabilities: (DNCA) offers the following capabilities:
1. Limits or defines the number of NAPT/NAT bindings made available 1. Limits or defines the number of NAPT/NAT bindings made available
to an individual end point or user. The main motivation for to an individual end point or user. The main motivation for
restricting the number of bindings on a per end point basis is to restricting the number of bindings on a per end point basis is to
protect the service of the service provider against denial of protect the service of the service provider against denial of
service attacks. If multiple end points share a single public IP service attacks. If multiple end points share a single public IP
address, these end points can share fate. If one end point would address, these end points can share fate. If one end point would
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mal-ware, etc.) be able to consume all available bindings for a mal-ware, etc.) be able to consume all available bindings for a
given single public IP address, service would be hampered (or given single public IP address, service would be hampered (or
might even become unavailable) for those other end points sharing might even become unavailable) for those other end points sharing
the same public IP address. The efficiency of a NAPT deployment the same public IP address. The efficiency of a NAPT deployment
depends on the maximum number of bindings an end point could use. depends on the maximum number of bindings an end point could use.
Given that the typical number of bindings an end point uses Given that the typical number of bindings an end point uses
depends on the type of end point (e.g. a personal computer of a depends on the type of end point (e.g. a personal computer of a
broadband user is expected to use a higher number of bindings broadband user is expected to use a higher number of bindings
than a simple mobile phone) and a NAPT device is often shared by than a simple mobile phone) and a NAPT device is often shared by
different types of end points, it is desirable to actively manage different types of end points, it is desirable to actively manage
the maximum number of bindings. the maximum number of bindings. This requirement is specified in
REQ-3 of [I-D.ietf-behave-lsn-requirements]
2. Supports the allocation of specific NAPT/NAT bindings. Two types 2. Supports the allocation of specific NAPT/NAT bindings. Two types
of specific bindings can be distinguished: of specific bindings can be distinguished:
* Allocation of a pre-defined NAT binding: Both the internal and * Allocation of a pre-defined NAT binding: Both the internal and
external IP address and port pair are specified within the external IP address and port pair are specified within the
request. Some deployment cases, such as access to a web- request. Some deployment cases, such as access to a web-
server within a user's home network with IP address and port, server within a user's home network with IP address and port,
benefit from statically configured bindings. benefit from statically configured bindings.
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example, a list of IP-subnets. Such external address pools can example, a list of IP-subnets. Such external address pools can
be used to select the external IP address in NAPT/NAT bindings be used to select the external IP address in NAPT/NAT bindings
for multiple subscribers. for multiple subscribers.
4. Generates reports and accounting records: Reports established 4. Generates reports and accounting records: Reports established
bindings for a particular user. The collected information is bindings for a particular user. The collected information is
used by accounting systems for statistical purposes. used by accounting systems for statistical purposes.
5. Queries and retrieves details about bindings on demand: This 5. Queries and retrieves details about bindings on demand: This
feature complements the previously mentioned accounting feature complements the previously mentioned accounting
functionality (see item 4). functionality (see item 4). This feature can be used by an
entity to find NAT-bindings belonging to one or multiple end
points on the NAT-device. The entity is not required to create a
DNCA control session to perform the query.
6. Identifies a subscriber or endpoint on multiple network devices 6. Identifies a subscriber or endpoint on multiple network devices
(NAT/NAPT device, the AAA-server, or the Network Access Server (NAT/NAPT device, the AAA-server, or the Network Access Server
(NAS)): Endpoint identification is facilitated through a Global (NAS)): Endpoint identification is facilitated through a Global
Endpoint ID. Endpoints are identified through a single or a set Endpoint ID. Endpoints are identified through a single or a set
of classifiers, such as IP address, Virtual Local Area Network of classifiers, such as IP address, Virtual Local Area Network
(VLAN) identifier, or interface identifier which uniquely (VLAN) identifier, or interface identifier which uniquely
identify the traffic associated with a particular global identify the traffic associated with a particular global
endpoint. endpoint.
With the above capabilities, DNCA qualifies as a MIDCOM protocol
[RFC3303], [RFC3304], [RFC5189] for middle boxes which perform NAT.
The MIDCOM protocol evaluation [RFC4097] evaluated Diameter as a
candidate protocol for MIDCOM. DNCA provides the extensions to the
Diameter base protocol [RFC3588] following the MIDCOM protocol
requirements, such as the support of NAT-specific rule transport,
support for oddity of mapped ports, as well as support for
consecutive range port numbers. DNCA adds to the MIDCOM protocol
capabilities in that it allows to maintain the reference to an end
point representing a user or subscriber in the control operation,
enabling the control of the behavior of a NAT-device on a per end
point basis. Following the requirements of different operators and
deployments, different management protocols are employed. Examples
include e.g. SNMP [RFC3411] and NETCONF [RFC6241] which can both be
used for device configuration. Similarly, DNCA is complementing
existing MIDCOM implementations, offering a MIDCOM protocol option
for operators with an operational environment that is Diameter-
focused which desire to use Diameter to perform per end point NAT
control.
This document is structured as follows: Section 2 lists terminology, This document is structured as follows: Section 2 lists terminology,
while Section 3 provides an introduction to DNCA and its overall while Section 3 provides an introduction to DNCA and its overall
deployment framework. Sections 4 to 8 cover DNCA specifics, with deployment framework. Sections 4 to 8 cover DNCA specifics, with
Section 4 describing session management, Section 5 the use of the Section 4 describing session management, Section 5 the use of the
Diameter base protocol, Section 6 new commands, Section 7 AVPs used, Diameter base protocol, Section 6 new commands, Section 7 Attribute
and Section 8 accounting aspects. Section 9 presents an AVP Value Pairs(AVPs) used, and Section 8 accounting aspects. Section 9
occurence table. IANA and security considerations are addressed in presents AVP occurrence tables. IANA and security considerations are
Sections 10 and 11. addressed in Sections 10 and 11.
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
Abbreviations used in this document: Abbreviations used in this document:
AAA: Authentication, Authorization, Accounting AAA: Authentication, Authorization, Accounting
DNCA: Diameter Network address and port translation Control DNCA: Diameter Network address and port translation Control
Application Application
NAPT: Network Address and Port Translation NAPT: Network Address and Port Translation, see also [RFC3022]
NAT: Network Address Translation (NAT and NAPT are used in this NAT: Network Address Translation (NAT and NAPT are used in this
document interchangeably) document interchangeably)
NAT-binding or binding: Association of two IP address/port pairs NAT-binding or binding: Association of two IP address/port pairs
(with one IP address typically being private and the other one (with one IP address typically being private and the other one
public) to facilitate NAT public) to facilitate NAT
NAT Binding Predefined template: Is a policy template or
configuration that is predefined at the NAT-device. It may
contain NAT-bindings, IP-address pools for allocating the external
IP-address of a NAT-binding, the maximum number of allowed NAT-
bindings for end-points, etc.
NAT-device: Network Address Translator or Network Address and Port NAT-device: Network Address Translator or Network Address and Port
Translator: An entity performing NAT or NAPT Translator: An entity performing NAT or NAPT.
NAT-controller: Entity controlling the behavior of a NAT-device NAT-controller: Entity controlling the behavior of a NAT-device.
NAS: Network Access Server NAS: Network Access Server
NCR: NAT Control Request NCR: NAT Control Request
NCA: NAT Control Answer NCA: NAT Control Answer
NAT44: IPv4 to IPv4 network address and port translation, see
[RFC2663]
NAT64: IPv6 to IPv4 address family translation, see [RFC6145] and
[RFC6146]
PPP: Point-to-Point Protocol [RFC1661]
3. Deployment Framework 3. Deployment Framework
3.1. Deployment Scenario 3.1. Deployment Scenario
Figure 1 shows a typical network deployment for Internet access. A Figure 1 shows a typical network deployment for IPv4-Internet access.
user's IPv4 host gains access to the Internet though a NAS, which A user's IPv4 host gains access to the Internet though a NAS, which
facilitates the authentication of the endpoint and configures the facilitates the authentication of the endpoint and configures the
user's connection according to the authorization and configuration user's connection according to the authorization and configuration
data received from the AAA-server upon successful authentication. data received from the AAA-server upon successful authentication.
Public IPv4 addresses are used throughout the network. Public IPv4 addresses are used throughout the network.
+---------+ +---------+
| | | |
| AAA | | AAA |
| | | |
+---------+ +---------+
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+---------+ +---------+ +----------+ +---------+ +---------+ +----------+
| IPv4 | | | | IPv4 | | IPv4 | | | | IPv4 |
| Host |----------| NAS |-------------| Internet | | Host |----------| NAS |-------------| Internet |
| | | | | | | | | | | |
+---------+ +---------+ +----------+ +---------+ +---------+ +----------+
<-------------------- Public IPv4 ----------------------> <-------------------- Public IPv4 ---------------------->
Figure 1: Typical network deployment for internet access Figure 1: Typical network deployment for internet access
Figure 2 depicts the deployment scenario when a service provider Figure 2 depicts the deployment scenario where a service provider
introduces a NAT-device to increase the efficiency of the global IPv4 places a NAT between the host and the public Internet. The objective
address pool utilization. The objective is to provide the customer is to provide the customer with connectivity to the public IPv4
with connectivity to the public IPv4 Internet. The NAT-device Internet. The NAT-device performs network address and port (and
performs network address and port (and optionally address family) optionally address family) translation, depending on whether the
translation, depending on whether the access network uses private access network uses private IPv4 addresses or public IPv6 addresses,
IPv4 addresses or public IPv6 addresses, to public IPv4 addresses. to public IPv4 addresses. Note that there may be more than one NAS,
NAT-device, or AAA-entity in a deployment, although the figures only
depict one entity each for clarity.
If the NAT-device would be put in place without any endpoint If the NAT-device would be put in place without any endpoint
awareness, the service offerings of the service provider could be awareness, the service offerings of the service provider could be
impacted. This includes cases like: impacted as detailed in [I-D.ietf-behave-lsn-requirements]. This
includes cases like:
o Provisioning static NAT bindings for particular endpoints o Provisioning static NAT bindings for particular endpoints
o Using different public IP address pools for different set of o Using different public IP address pools for different set of
endpoints (for example, residential or business customers) endpoints (for example, residential or business customers)
o Reporting allocated bindings on a per endpoint basis o Reporting allocated bindings on a per endpoint basis
o Integrate control of the NAT-device into the already existing per o Integrate control of the NAT-device into the already existing per
endpoint management infrastructure of the service provider endpoint management infrastructure of the service provider
skipping to change at page 9, line 14 skipping to change at page 9, line 38
+---------+ +---------+
| | | |
| AAA | | AAA |
| | | |
+---------+ +---------+
| |
| |
| |
| |
+--------+ +---------+ +--------+ +----------+ +--------+ +---------+ +--------+ +----------+
| IPv4/ | | | | | | IPv4 | | | | | | | | |
| IPv6 |----| NAS |----| NAT- |----| Internet | | Host |----| NAS |----| NAT- |----| IPv4- |
| Host | | | | device | | | | | | | | device | | Internet |
+--------+ +---------+ +--------+ +----------+ +--------+ +---------+ +--------+ +----------+
<-------- Private IPv4 ----------><--- Public IPv4 --->
<-------- Public IPv6 ----------><--- Public IPv4 ---> For NAT44 deployments (IPv4 host):
<----- Private IPv4 ----------><--- Public IPv4 --->
For NAT64 deployments (IPv6 host):
<----- Public IPv6 ----------><--- Public IPv4 --->
Figure 2: Access network deployment with NAT Figure 2: Access network deployment with NAT
Figure 2 shows a typical deployment for IPv4-Internet access
involving a NAT-device within the service provider network. The
figure describes two scenarios: One where an IPv4-host (with a
private IPv4 address) accesses the IPv4-Internet, as well as one
where an IPv6-host accesses the IPv4-Internet.
3.2. Diameter NAPT Control Application Overview 3.2. Diameter NAPT Control Application Overview
DNCA runs between two DNCA Diameter peers. One DNCA Diameter peer DNCA runs between two DNCA Diameter peers. One DNCA Diameter peer
resides within the NAT-device, the other DNCA Diameter peer resides resides within the NAT-device, the other DNCA Diameter peer resides
within the NAT-Controller. DNCA allows per endpoint control and within a NAT-controller (discussed in Section 3.3). DNCA allows per
management of NAT within the NAT-device. Based on Diameter, DNCA endpoint control and management of NAT within the NAT-device. Based
integrates well with the suite of Diameter applications deployed for on Diameter, DNCA integrates well with the suite of Diameter
per endpoint authentication, authorization, accounting, and policy applications deployed for per endpoint authentication, authorization,
control in service provider networks. accounting, and policy control in service provider networks.
DNCA offers: DNCA offers:
o Request and answer commands to control the allowed number of NAT o Request and answer commands to control the allowed number of NAT
bindings per endpoint , to request the allocation of specific bindings per endpoint to request the allocation of specific
bindings for an endpoint, to define the address pool to be used bindings for an endpoint, to define the address pool to be used
for an endpoint. for an endpoint.
o Provides per endpoint reporting of the allocated NAT bindings. o Provides per endpoint reporting of the allocated NAT bindings.
o Provides unique identification of an endpoint on NAT-device, AAA- o Provides unique identification of an endpoint on NAT-device, AAA-
server and NAS, to simplify correlation of accounting data server and NAS, to simplify correlation of accounting data
streams. streams.
DNCA allows controlling the behavior of a NAT-device on a per DNCA allows controlling the behavior of a NAT-device on a per
endpoint basis during initial session establishment and at later endpoint basis during initial session establishment and at later
stages by providing an update procedure for already established stages by providing an update procedure for already established
sessions. Using DNCA, per endpoint NAT binding information can be sessions. Using DNCA, per endpoint NAT binding information can be
retrieved either using accounting mechanisms or through an explicit retrieved either using accounting mechanisms or through an explicit
session query to the NAT. session query to the NAT.
3.3. Deployment Scenarios For DNCA 3.3. Deployment Scenarios For DNCA
DNCA can be deployed in different ways. Two common deployment DNCA can be deployed in different ways. DNCA supports deployments
scenarios are outlined in Figure 3 ("integrated deployment") and with "n" NAT-controllers and "m" NAT-devices, with n and m equal to
Figure 4 ("autonomous deployment"). The two scenarios differ in or greater than 1. For DNCA, the session representing a particular
which entity fulfills the role of the NAT-controller. Within the endpoint is atomic. Any deployment MUST ensure that for every given
figures (C) denotes the network element performing the role of the endpoint only a single NAT-controller and only a single NAT-device
NAT-controller. are active at any point in time. This is to ensure that NAT-devices
controlled by multiple NAT-controllers do not receive conflicting
control requests for a particular endpoint, or would be unclear which
NAT-controller to send accounting information to.
Two common deployment scenarios are outlined in Figure 3 ("integrated
deployment") and Figure 4 ("autonomous deployment"). Per the note
above, multiple instances of NAT-controllers and NAT-devices could be
deployed. The figures only show single instances for reasons of
clarity. The two shown scenarios differ in which entity fulfills the
role of the NAT-controller. Within the figures (C) denotes the
network element performing the role of the NAT-controller.
The integrated deployment approach hides the existence of the NAT- The integrated deployment approach hides the existence of the NAT-
device from external servers, such as the AAA-server. It is suited device from external servers, such as the AAA-server. It is suited
for environments where minimal changes to the existing AAA deployment for environments where minimal changes to the existing AAA deployment
are desired. The NAS and the NAT-device are Diameter peers are desired. The NAS and the NAT-device are Diameter peers
supporting the DNCA. The Diameter peer within the NAS, performing supporting the DNCA. The Diameter peer within the NAS, performing
the role of the NAT-controller, initiates and manages sessions with the role of the NAT-controller, initiates and manages sessions with
the NAT-device, exchanges NAT specific configuration information and the NAT-device, exchanges NAT specific configuration information and
handles reporting and accounting information. The NAS receives handles reporting and accounting information. The NAS receives
reporting and accounting information from NAT-device. With this reporting and accounting information from the NAT-device. With this
information, the NAS can provide a single accounting record for the information, the NAS can provide a single accounting record for the
endpoint. A system correlating the accounting information received endpoint. A system correlating the accounting information received
from NAS and NAT-device would not be needed. from the NAS and NAT-device would not be needed.
An example network attachment for an integrated NAT deployment can be An example network attachment for an integrated NAT deployment can be
described as follows: An endpoint connects to the network, with the described as follows: An endpoint connects to the network, with the
NAS being the point of attachment. After successful authentication, NAS being the point of attachment. After successful authentication,
the NAS receives endpoint related authorization data from the AAA- the NAS receives endpoint related authorization data from the AAA-
server. A portion of the authorization data applies to per endpoint server. A portion of the authorization data applies to per endpoint
configuration on the NAS itself, another portion describes configuration on the NAS itself, another portion describes
authorization and configuration information for NAT control aimed at authorization and configuration information for NAT control aimed at
the NAT-device. The NAS initiates a DNCA session to the NAT-device the NAT-device. The NAS initiates a DNCA session to the NAT-device
and sends relevant authorization and configuration information for and sends relevant authorization and configuration information for
skipping to change at page 11, line 14 skipping to change at page 12, line 14
+---------+ +---------+
| | | |
| AAA | | AAA |
| | | |
+---------+ +---------+
| |
| |
| |
+--------+ +---------+ +--------+ +----------+ +--------+ +---------+ +--------+ +----------+
| IPv4/ | | (C) | | | | IPv4 | | | | (C) | | | | |
| IPv6 |----| NAS |----| NAT- |----| Internet | | Host |----| NAS |----| NAT- |----| IPv4- |
| Host | | | | device | | | | | | | | device | | Internet |
+--------+ +---------+ +--------+ +----------+ +--------+ +---------+ +--------+ +----------+
<-------- Public IPv6 ----------><--- Public IPv4 --->
<-------- Private IPv4 ----------><--- Public IPv4 ---> For NAT44 deployments (IPv4 host):
<----- Private IPv4 ----------><--- Public IPv4 --->
For NAT64 deployments (IPv6 host):
<----- Public IPv6 ----------><--- Public IPv4 --->
Figure 3: NAT control deployment: Integrated deployment Figure 3: NAT control deployment: Integrated deployment
The autonomous deployment approach decouples user management on NAS Figure 3 shows examples of integrated deployments. The figure
and NAT-device. In the autonomous deployment approach, the AAA- describes two scenarios: One where an IPv4-host (with a private IPv4
address) accesses the IPv4-Internet, as well as one where an IPv6-
host accesses the IPv4-Internet.
The autonomous deployment approach decouples user management on the
NAS and NAT-device. In the autonomous deployment approach, the AAA-
system and the NAT-device are the Diameter peers running the DNCA. system and the NAT-device are the Diameter peers running the DNCA.
The AAA-system also serves as NAT-controller. It manages the The AAA-system also serves as NAT-controller. It manages the
connection to the NAT-device, controls the per endpoint connection to the NAT-device, controls the per endpoint
configuration, and also receives accounting and reporting information configuration, and also receives accounting and reporting information
from the NAT-device. Different from the integrated deployment from the NAT-device. Different from the integrated deployment
scenario, the autonomous deployment scenario does not "hide" the scenario, the autonomous deployment scenario does not "hide" the
existence of the NAT-device from the AAA infrastructure. Here two existence of the NAT-device from the AAA infrastructure. Here two
accounting streams are received by the AAA-server for one particular accounting streams are received by the AAA-server for one particular
endpoint, one from the NAS, and one from the NAT-device. endpoint, one from the NAS, and one from the NAT-device.
+---------+ +---------+
| (C) | | (C) |
| AAA |--------- | AAA |---------
| | | | | |
+---------+ | +---------+ |
| | | |
| | | |
| | | |
+--------+ +---------+ +---------+ +----------+ +--------+ +---------+ +---------+ +----------+
| IPv4/ | | | | | | IPv4 | | IPv4/ | | | | | | IPv4 |
| IPv6 |----| NAS |----| NAT- |----| Internet | | IPv6 |----| NAS |----| NAT- |----| Internet |
| Host | | | | device | | | | Host | | | | device | | |
+--------+ +---------+ +---------+ +----------+ +--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><---- Public IPv4 --->
<-------- Private IPv4 ----------><---- Public IPv4 ---> For NAT44 deployments (IPv4 host):
<----- Private IPv4 ----------><--- Public IPv4 --->
For NAT64 deployments (IPv6 host):
<----- Public IPv6 ----------><--- Public IPv4 --->
Figure 4: NAT control deployment: Autonomous deployment Figure 4: NAT control deployment: Autonomous deployment
Figure 4 shows examples of autonomous deployments. The figure
describes two scenarios: One where an IPv4-host (with a private IPv4
address) accesses the IPv4-Internet, as well as one where an IPv6-
host accesses the IPv4-Internet.
4. DNCA Session Establishment and Management 4. DNCA Session Establishment and Management
Note that this section forward references some of the commands and Note that this section forward references some of the commands and
AVPs defined for DNCA. Please refer to Section 6 and Section 8 for AVPs defined for DNCA. Please refer to Section 6 and Section 8 for
details. DNCA runs between a Diameter peer residing in a NAT- details. DNCA runs between a Diameter peer residing in a NAT-
controller and a Diameter peer residing in a NAT-device. The controller and a Diameter peer residing in a NAT-device. The
Diameter peer within the NAT-controller is always the control Diameter peer within the NAT-controller is always the control
requesting entity: It initiates, updates, or terminates the sessions. requesting entity: It initiates, updates, or terminates the sessions.
Sessions are initiated when the NAT-controller learns about a new Sessions are initiated when the NAT-controller learns about a new
endpoint (i.e., host) that requires a NAT service. This could for endpoint (i.e., host) that requires a NAT service. This could for
example be due to the entity hosting the NAT-controller receiving example be due to the entity hosting the NAT-controller receiving
authentication, authorization, or accounting requests for or from the authentication, authorization, or accounting requests for or from the
endpoint. Alternate methods that could trigger session set up endpoint. Alternate methods that could trigger session setup include
include local configuration, receipt of a packet from a formerly local configuration, receipt of a packet from a formerly unknown IP-
unknown IP-address, etc. address, etc.
4.1. Session Establishment 4.1. Session Establishment
The DNCA Diameter peer within the NAT-controller establishes a The DNCA Diameter peer within the NAT-controller establishes a
session with the DNCA Diameter peer within the NAT-device to control session with the DNCA Diameter peer within the NAT-device to control
the behavior of the NAT function within the NAT-device. During the behavior of the NAT function within the NAT-device. During
session establishment, the DNCA Diameter peer within the NAT- session establishment, the DNCA Diameter peer within the NAT-
controller passes along configuration information to DNCA Diameter controller passes along configuration information to DNCA Diameter
peer within the NAT-device. The session configuration information peer within the NAT-device. The session configuration information
comprises the maximum number of bindings allowed for the endpoint comprises the maximum number of bindings allowed for the endpoint
skipping to change at page 12, line 46 skipping to change at page 14, line 25
NAT-device with NC-Request-Type AVP set to INITIAL_REQUEST to NAT-device with NC-Request-Type AVP set to INITIAL_REQUEST to
initiate a Diameter NAT control session. On receipt of a NCR the initiate a Diameter NAT control session. On receipt of a NCR the
DNCA Diameter peer within the NAT-device sets up a new session for DNCA Diameter peer within the NAT-device sets up a new session for
the endpoint associated with the endpoint classifier(s) contained in the endpoint associated with the endpoint classifier(s) contained in
the NCR. The DNCA Diameter peer within the NAT-device notifies its the NCR. The DNCA Diameter peer within the NAT-device notifies its
DNCA Diameter peer within the NAT-controller about successful session DNCA Diameter peer within the NAT-controller about successful session
setup using a NAT-Control Answer (NCA) message with Result-Code set setup using a NAT-Control Answer (NCA) message with Result-Code set
to DIAMETER_SUCCESS. Figure 5 shows the initial protocol interaction to DIAMETER_SUCCESS. Figure 5 shows the initial protocol interaction
between the two DNCA Diameter peers. between the two DNCA Diameter peers.
The initial NAT-Control-Request may contain configuration information The initial NAT-Control-Request MAY contain configuration information
for the session, which specifies the behavior of the NAT-device for for the session, which specifies the behavior of the NAT-device for
the session. The configuration information which may be included, the session. The configuration information that MAY be included,
comprises: comprises:
o A list of NAT bindings, which should be pre-allocated for the o A list of NAT bindings, which should be pre-allocated for the
session; for example, in case a user requires a fixed external IP- session; for example, in case a user requires a fixed external IP-
address/port pair for one of his applications. address/port pair for one of his applications.
o The maximum number of NAT-bindings allowed for an endpoint. o The maximum number of NAT-bindings allowed for an endpoint.
o A description of the external IP-address pool(s) to be used for o A description of the external IP-address pool(s) to be used for
the session. the session.
o A reference to a predefined binding rule on the NAT-device, which o A reference to a NAT Binding Predefined template on the NAT-
is applied to the session. Such a predefined binding rule on the device, which is applied to the session. Such a NAT Binding
NAT-device may contain, for example, the name of the IP-address Predefined template on the NAT-device may contain, for example,
pool that external IP-addresses should be allocated from, the the name of the IP-address pool that external IP-addresses should
maximum number of bindings permitted for the endpoint, etc. be allocated from, the maximum number of bindings permitted for
the endpoint, etc.
In certain cases, the NAT-device may not be able to perform the tasks In certain cases, the NAT-device may not be able to perform the tasks
requested within the NCR. These include the following: requested within the NCR. These include the following:
o If a DNCA Diameter peer within the NAT-device receives a NCR from o If a DNCA Diameter peer within the NAT-device receives a NCR from
a DNCA Diameter peer within a NAT-controller with NC- Request-Type a DNCA Diameter peer within a NAT-controller with NC-Request-Type
AVP set to INITIAL_REQUEST that identifies an already existing AVP set to INITIAL_REQUEST that identifies an already existing
session; that is, DNCA Diameter peer and endpoint identifier match session; that is, DNCA Diameter peer and endpoint identifier match
an already existing session, the DNCA Diameter peer within the an already existing session, the DNCA Diameter peer within the
NAT-device returns NCA with Result-Code set to SESSION_EXISTS, and NAT-device MUST return an NCA with Result-Code set to
provides the Session-Id of the existing session in the Duplicate- SESSION_EXISTS, and provide the Session-Id of the existing session
Session-Id AVP. in the Duplicate-Session-Id AVP.
o If a DNCA Diameter peer within the NAT-device receives a NCR from o If a DNCA Diameter peer within the NAT-device receives a NCR from
a DNCA Diameter peer within a NAT-controller with NC- Request-Type a DNCA Diameter peer within a NAT-controller with NC-Request-Type
AVP set to INITIAL_REQUEST that matches more than one of the AVP set to INITIAL_REQUEST that matches more than one of the
already existing sessions; that is, DNCA Diameter peer and already existing sessions; that is, DNCA Diameter peer and
endpoint identifier match already existing sessions, the DNCA endpoint identifier match already existing sessions, the DNCA
Diameter peer within the NAT-device returns a NCA with Result-Code Diameter peer within the NAT-device MUST return an NCA with
set to INSUFFICIENT-CLASSIFIERS. In case a DNCA Diameter peer Result-Code set to INSUFFICIENT-CLASSIFIERS. In case a DNCA
receives a NCA that reports Insufficient-Classifiers, it may Diameter peer receives a NCA that reports Insufficient-
choose to retry establishing a new session using additional or Classifiers, it MAY choose to retry establishing a new session
more specific classifiers. using additional or more specific classifiers.
o If the NCR contains a binding rule not defined on the NAT-device, o If the NCR contains a NAT Binding Predefined template not defined
the DNCA Diameter peer within the NAT-device returns NCA with on the NAT-device, the DNCA Diameter peer within the NAT-device
Result-Code AVP set to UNKNOWN_BINDING_RULE. MUST return an NCA with Result-Code AVP set to
UNKNOWN_BINDING_TEMPLATE_NAME.
o In case the NAT-device is unable to establish all of the bindings o In case the NAT-device is unable to establish all of the bindings
requested in the NCR, the DNCA Diameter peer will return a NCA requested in the NCR, the DNCA Diameter peer MUST return an NCA
with Result-Code set to BINDING_FAILURE. A DNCA Diameter peer with Result-Code set to BINDING_FAILURE. A DNCA Diameter peer
within a NAT-device treats a NCR as an atomic operation; hence within a NAT-device MUST treat a NCR as an atomic operation; hence
none of the requested bindings will be established by the NAT- none of the requested bindings will be established by the NAT-
device. Either all requested actions within a NCR are completed device. Either all requested actions within a NCR MUST be
successfully, or the entire request fails. completed successfully, or the entire request fails.
o If a NAT-device does not have sufficient resources to process a o If a NAT-device does not have sufficient resources to process a
request, the DNCA Diameter peer returns a NCA with Result-Code set request, the DNCA Diameter peer MUST return an NCA with Result-
to RESOURCE_FAILURE. Code set to RESOURCE_FAILURE.
o In case Max-NAT-Binding and NAT-Control-Definition are included in o In case Max-NAT-Binding, NAT-Control-Definition as well as NAT-
the NCR along with a reference to a binding rule; that is, a Control-Binding-Template are included in the NCR, and the values
predefined template on NAT-device, and the values in Max-NAT- in Max-NAT-Binding and NAT-Control-Definition contradict those
Binding and NAT-Control-Definition contradict those specified in specified in the pre-provisioned template on the NAT-device which
the pre-defined binding rule, Max-NAT-Binding and NAT-Control- NAT-Control-Binding-Template references, Max-NAT-Binding and NAT-
Definition override the values specified in the binding rule. Control-Definition MUST override the values specified in the
template that NAT-Control-Binding-Template refers to.
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer) NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| | | |
| | | |
| | | |
Trigger | Trigger |
| | | |
| NCR | | NCR |
|------------------------------------------>| |------------------------------------------>|
| (INITIAL_REQUEST, endpoint classifier, |
| session id, NAT control config data) |
| | | |
| | | |
| | | |
| | | |
| If Able to comply | If Able to comply
| with Request then | with Request then
| Create session state | Create session state
| | | |
| | | |
| NCA | | NCA |
|<------------------------------------------| |<------------------------------------------|
| (result code) |
| | | |
| | | |
Figure 5: Initial NAT control request and session establishment Figure 5: Initial NAT control request and session establishment
Note: The DNCA Diameter peer within the NAT-device creates session Note: The DNCA Diameter peer within the NAT-device creates session
state only if it is able to comply with the NCR. On success it will state only if it is able to comply with the NCR. On success it will
reply with a NCA with Result-Code set to DIAMETER_SUCCESS. reply with an NCA with Result-Code set to DIAMETER_SUCCESS.
4.2. Session Re-Authorization 4.2. Session Re-Authorization
Session re-authorization is performed if the NAT-controller desires Session re-authorization is performed if the NAT-controller desires
to change the behavior of the NAT-device for an existing session. to change the behavior of the NAT-device for an existing session.
Session re-authorization could be used, for example, to change the Session re-authorization could be used, for example, to change the
number of allowed bindings for a particular session, or establish or number of allowed bindings for a particular session, or establish or
remove a pre-defined binding. remove a pre-defined binding.
The DNCA Diameter peer within the NAT-controller generates a NCR The DNCA Diameter peer within the NAT-controller generates a NCR
message to DNCA Diameter peer within NAT-device with NC-Request-Type message to the DNCA Diameter peer within the NAT-device with NC-
AVP set to UPDATE_REQUEST upon receiving a trigger signal. If the Request-Type AVP set to UPDATE_REQUEST upon receiving a trigger
session is updated successfully, the DNCA Diameter peer within the signal. If the session is updated successfully, the DNCA Diameter
NAT-device notifies the DNCA Diameter peer within the NAT-controller peer within the NAT-device notifies the DNCA Diameter peer within the
about the successful session update using a NAT-Control Answer (NCA) NAT-controller about the successful session update using a NAT-
message with Result-Code set to DIAMETER_SUCCESS. Figure 6 shows the Control Answer (NCA) message with Result-Code set to
protocol interaction between the two DNCA Diameter peers. DIAMETER_SUCCESS. Figure 6 shows the protocol interaction between
the two DNCA Diameter peers.
In certain cases, the NAT-device may not be able to perform the tasks In certain cases, the NAT-device may not be able to perform the tasks
requested within the NCR. These include the following: requested within the NCR. These include the following:
o If DNCA Diameter peer within a NAT-device receives a NCR update or o If DNCA Diameter peer within a NAT-device receives an NCR update
query request for a non-existent session, it sets Result-Code in or query request for a non-existent session, it MUST set Result-
the answer to DIAMETER_UNKNOWN_SESSION_ID. Code in the answer to DIAMETER_UNKNOWN_SESSION_ID.
o If the NCR contains a binding rule not defined on the NAT-device, o If the NCR contains a NAT Binding Predefined template not defined
a NCA with Result-Code AVP set to UNKNOWN_BINDING_RULE is on the NAT-device, an NCA with Result-Code AVP set to
returned. UNKNOWN_BINDING_TEMPLATE_NAME MUST be returned.
o If the NAT-device cannot establish the requested binding because o If the NAT-device cannot establish the requested binding because
the maximum number of allowed bindings has been reached for the the maximum number of allowed bindings has been reached for the
endpoint classifier, a NCA with Result-Code AVP set to endpoint classifier, an NCA with Result-Code AVP set to
MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT by the DNCA Diameter peer. MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT MUST be returned to the DNCA
Diameter peer.
o If the NAT-device cannot establish some or all of the bindings o If the NAT-device cannot establish some or all of the bindings
requested in a NCR, but has not yet reached the maximum number of requested in an NCR, but has not yet reached the maximum number of
allowed bindings for the endpoint, a NCA with Result-Code set to allowed bindings for the endpoint, an NCA with Result-Code set to
BINDING_FAILURE is returned. As already noted, the DNCA Diameter BINDING_FAILURE MUST be returned. As already noted, the DNCA
peer in a NAT-device treats a NCR as an atomic operation. Hence Diameter peer in a NAT-device MUST treat an NCR as an atomic
none of the requested bindings will be established by the NAT- operation. Hence none of the requested bindings will be
device in case of failure. Actions requested within a NCR are established by the NAT-device in case of failure. Actions
either all successful or all fail. requested within a NCR are either all successful or all fail.
o If the NAT-device does not have sufficient resources to process a o If the NAT-device does not have sufficient resources to process a
request, a NCA with Result-Code set to RESOURCE_FAILURE is request, an NCA with Result-Code set to RESOURCE_FAILURE MUST be
returned. returned.
o If a NCR redefines the maximum number of NAT-bindings allowed for o If an NCR redefines the maximum number of NAT-bindings allowed for
the endpoint, the new value will override any previously defined the endpoint, the new value MUST override any previously defined
limit on NAT bindings. It depends on the implementation of the 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 NAT-device on how the NAT-device copes with a case where the new
value is lower than the actual number of allocated bindings. value is lower than the actual number of allocated bindings. The
Typically the NAT-device refrains from enforcing the new limit NAT-device MAY refrain from enforcing the new limit immediately
immediately; that is, actively remove bindings, but rather (that is, actively remove bindings), but rather disallows the
disallow the establishment of new bindings until the current establishment of new bindings until the current number of bindings
number of bindings is lower than the newly established maximum is lower than the newly established maximum number of allowed
number of allowed bindings. bindings.
o If a NCR specifies a new binding rule, predefined on the NAT- o If an NCR specifies a new NAT Binding Predefined template on the
device, the binding rule overrides any previously defined rule for NAT-device, the NAT Binding Predefined template overrides any
the session. previously defined rule for the session.
o If Max-NAT-Binding and NAT-Control-Definition AVPs are included in o In case Max-NAT-Binding, NAT-Control-Definition as well as NAT-
the NCR along with a reference to a binding rule (a predefined Control-Binding-Template are included in the NCR, and the values
template on the NAT-device) and the values in Max-NAT-Binding and in Max-NAT-Binding and NAT-Control-Definition contradict those
NAT-Control-Definition AVPs contradict those specified in the pre- specified in the pre-provisioned template on the NAT-device which
defined binding rule, Max-NAT-Binding and NAT-Control-Definition NAT-Control-Binding-Template references, Max-NAT-Binding and NAT-
AVPs override the values specified in the binding rule. Control-Definition MUST override the values specified in the
template that the NAT-Control-Binding-Template refers to.
Note: Already established bindings for the session will not be Note: Already established bindings for the session SHOULD NOT be
affected in case the tasks requested within the NCR cannot be affected in case the tasks requested within the NCR cannot be
completed. completed.
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer) NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| | | |
| | | |
| | | |
Change of session | Change of session |
attributes | attributes |
| | | |
| NCR | | NCR |
|------------------------------------------>| |------------------------------------------>|
| (UPDATE_REQUEST session id, |
| NAT control config data) |
| | | |
| | | |
| If able to comply | If able to comply
| with the request: | with the request:
| Update session state | Update session state
| | | |
| | | |
| NCA | | NCA |
|<------------------------------------------| |<------------------------------------------|
| (result code) |
| |
| | | |
Figure 6: NAT control request for session update Figure 6: NAT control request for session update
4.3. Session and Binding Query 4.3. Session and Binding Query
Session query can be used by the DNCA Diameter peer within the NAT- A Session and NAT-binding query MAY be used by the DNCA Diameter peer
controller to either retrieve information on the current bindings for within the NAT-controller to either retrieve information on the
a particular session at the NAT-device or discover the session current bindings for a particular session at the NAT-device or
identifier for a particular external IP address/port pair. discover the session identifier for a particular external IP address/
port pair.
A DNCA Diameter peer within the NAT-controller starts a session query A DNCA Diameter peer within the NAT-controller starts a session query
by sending a NCR message with NC-Request-Type AVP set to by sending an NCR message with NC-Request-Type AVP set to
QUERY_REQUEST. Figure 7 shows the protocol interaction between the QUERY_REQUEST. Figure 7 shows the protocol interaction between the
DNCA Diameter peers. DNCA Diameter peers.
Two types of query requests exist. The first type of query request 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 uses the session ID as input parameter to the query. It is to allow
the DNCA Diameter peer within the NAT-controller to retrieve the the DNCA Diameter peer within the NAT-controller to retrieve the
current set of bindings for a specific session. The second type of current set of bindings for a specific session. The second type of
query request is used to retrieve the session identifiers, along with query request is used to retrieve the session identifiers, along with
the associated bindings, matching a criteria. This enables the DNCA the associated bindings, matching a criteria. This enables the DNCA
Diameter peer within the NAT-controller to find those sessions, which Diameter peer within the NAT-controller to find those sessions, which
utilize a specific external IP-address. utilize a specific external IP-address.
1. Request a list of currently allocated NAT bindings for a 1. Request a list of currently allocated NAT bindings for a
particular session: On receiving a NCR, the NAT-device looks up particular session: On receiving a NCR, the NAT-device SHOULD
the session information for the session ID contained in the NCR, look up the session information for the session ID contained in
and reports all currently active NAT-bindings for the session the NCR, and report all currently active NAT-bindings for the
using a NCA message with Result-Code set to DIAMETER_SUCCESS. In session using an NCA message with Result-Code set to
this case the NCR MUST NOT contain a NAT-Control-Definition AVP. DIAMETER_SUCCESS. In this case the NCR MUST NOT contain a NAT-
Each NAT-binding is reported in a NAT-Control-Definition AVP. In Control-Definition AVP. Each NAT-binding is reported in a NAT-
case the session ID is unknown, the DNCA Diameter peer within the Control-Definition AVP. In case the session ID is unknown, the
NAT-device returns NCA with Result-Code set to DNCA Diameter peer within the NAT-device MUST return an NCA
DIAMETER_UNKNOWN_SESSION_ID. message with Result-Code set to DIAMETER_UNKNOWN_SESSION_ID.
2. Retrieve session IDs and internal IP address/port pairs for one 2. Retrieve session IDs and internal IP address/port pairs for one
or multiple external IP-address/port pairs: If the DNCA Diameter or multiple external IP-address/port pairs: If the DNCA Diameter
peer within the NAT-controller wishes to retrieve the session peer within the NAT-controller wishes to retrieve the session
ID(s) for one or multiple external IP-address/port pairs, it MUST 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- include the external IP-address/port pair(s) as part of the NAT-
Control-Definition AVP of the NCR. The session ID is not Control-Definition AVP of the NCR. The external IP-address/port
included in the NCR or the NCA for this type of a query. The pair(s) are pre-known to the controller via configuration, AAA
DNCA Diameter peer within the NAT-device reports the NAT-bindings interactions, or other means. The session ID is not included in
and associated session IDs corresponding to the external IP- the NCR or the NCA for this type of a query. The DNCA Diameter
address/port pairs in a NCA message with Result-Code set to peer within the NAT-device SHOULD report the NAT-bindings and
DIAMETER_SUCCESS with the same session ID, which was used in NCR. associated session IDs corresponding to the external IP-address/
In case an external IP-address/port pair has no associated port pairs in an NCA message using one or multiple instances of
existing NAT-binding, the NAT-Control-Definition AVP contained in the NAT-Control-Definition AVP. The Result-Code is set to
the reply just contains the NAT-External-Address AVP. DIAMETER_SUCCESS. 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.
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer) NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| | | |
| | | |
| | | |
DNCA Session Established | DNCA Session Established |
| | | |
| NCR | | NCR |
|------------------------------------------>| |------------------------------------------>|
| (QUERY_REQUEST) | | |
| | | |
| | | |
| | | |
| Look up corresponding session | Look up corresponding session
| and associated NAT-bindings | and associated NAT-bindings
| | | |
| NCA | | NCA |
|<------------------------------------------| |<------------------------------------------|
| (Result-Code) | | |
| | | |
| | | |
Figure 7: Session query Figure 7: Session query
4.4. Session Termination 4.4. Session Termination
Similar to session initiation, session tear down is always initiated Similar to session initiation, session tear down MUST be initiated by
by the DNCA Diameter peer within the NAT-controller. The DNCA the DNCA Diameter peer within the NAT-controller. The DNCA Diameter
Diameter peer sends a Session Terminate Request (STR) message to its peer sends a Session Terminate Request (STR) message to its peer
peer within the NAT-device upon receiving a trigger signal. The within the NAT-device upon receiving a trigger signal. The source of
source of the trigger signal is outside the scope of this document. the trigger signal is outside the scope of this document. As part of
In response, the DNCA Diameter peer within the NAT-device sends an STR message processing the DNCA Diameter peer within the NAT-device
accounting stop record reporting all bindings and notifies its DNCA MAY send an accounting stop record reporting all bindings. All the
Diameter peer about successful session termination using a Session NAT-bindings belonging to the session are removed and the session
Terminate Answer (STA) message with Result-Code set to state is cleaned up. The DNCA Diameter peer within the NAT-device
DIAMETER_SUCCESS. Figure 8 shows the protocol interaction between MUST notify its DNCA Diameter peer in the NAT-controller about
the two DNCA Diameter peers. successful session termination using a Session Terminate Answer (STA)
message with Result-Code set to DIAMETER_SUCCESS. Figure 8 shows the
protocol interaction between the two DNCA Diameter peers.
If a DNCA Diameter peer within a NAT-device receives a STR and fails If a DNCA Diameter peer within a NAT-device receives a STR and fails
to find a matching session, the DNCA Diameter peer returns a STA with to find a matching session, the DNCA Diameter peer MUST return a STA
Result-Code set to DIAMETER_UNKNOWN_SESSION_ID. with Result-Code set to DIAMETER_UNKNOWN_SESSION_ID.
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer) NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| | | |
| | | |
Trigger | Trigger |
| | | |
| STR | | STR |
|------------------------------------------->| |------------------------------------------->|
| (session id) |
| | | |
| | | |
| Remove NAT-bindings | |
| of session
| | | |
| | | |
| Send accounting stop | | Send accounting stop |
|<-------------------------------------------| |<-------------------------------------------|
| reporting all session bindings | | reporting all session bindings |
| | | |
| |
| Remove NAT-bindings
| of session
| |
| Terminate session / | Terminate session /
| Remove session state | Remove session state
| | | |
| | | |
| | | |
| STA | | STA |
|<-------------------------------------------| |<-------------------------------------------|
| (Result-Code) | | |
| | | |
Figure 8: Terminate NAT control session Figure 8: Terminate NAT control session
4.5. Session Abort 4.5. Session Abort
An Abort-Session-Request (ASR) message is sent from the DNCA Diameter An Abort-Session-Request (ASR) message is sent from the DNCA Diameter
peer within the NAT-device to the DNCA Diameter peer within the NAT- peer within the NAT-device to the DNCA Diameter peer within the NAT-
controller when it is unable to maintain a session due to resource controller when it is unable to maintain a session due to resource
limitations. The DNCA Diameter peer within the NAT-controller limitations. The DNCA Diameter peer within the NAT-controller MUST
acknowledges successful session abort using a Abort Session Answer acknowledge successful session abort using a Abort Session Answer
(ASA) message with Result-Code set to DIAMETER_SUCCESS. Figure 9 (ASA) message with Result-Code set to DIAMETER_SUCCESS. Figure 9
shows the protocol interaction between the DNCA Diameter peers. The shows the protocol interaction between the DNCA Diameter peers. The
DNCA Diameter peers will start a session termination procedure as DNCA Diameter peers will start a session termination procedure as
described in Section 4.4 following an ASA with Result-Code set to described in Section 4.4 following an ASA with Result-Code set to
DIAMETER_SUCCESS. DIAMETER_SUCCESS.
If the DNCA Diameter peer within a NAT-controller receives an ASR but If the DNCA Diameter peer within a NAT-controller receives an ASR but
fails to find a matching session, it returns an ASA with Result-Code fails to find a matching session, it MUST return an ASA with Result-
set to DIAMETER_UNKNOWN_SESSION_ID. If the DNCA Diameter peer within Code set to DIAMETER_UNKNOWN_SESSION_ID. If the DNCA Diameter peer
the NAT-controller is unable to comply with the ASR for any other within the NAT-controller is unable to comply with the ASR for any
reason, an ASA with Result-Code set to DIAMETER_UNABLE_TO_COMPLY is other reason, an ASA with Result-Code set to
returned. DIAMETER_UNABLE_TO_COMPLY MUST be returned.
NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer) NAT-controller (DNCA Diameter peer) NAT-device (DNCA Diameter peer)
| | | |
| | | |
| Trigger | Trigger
| | | |
| ASR | | ASR |
|<-------------------------------------------| |<-------------------------------------------|
| (session id) | | |
| | | |
| | | |
| ASA | | ASA |
|------------------------------------------->| |------------------------------------------->|
| (Result-Code) | | |
| | | |
| | | |
| On successful ASA | | On successful ASA |
|<------Session Termination Procedure------->| |<------Session Termination Procedure------->|
Figure 9: Abort NAT control session Figure 9: Abort NAT control session
4.6. Failure cases of the DNCA Diameter peers 4.6. Failure cases of the DNCA Diameter peers
This document does not specify the behavior in case NAT-device and This document does not specify the behavior in case the NAT-device
NAT-controller, or their respective DNCA Diameter peers are out of and NAT-controller, or their respective DNCA Diameter peers are out
sync. This could happen for example if one of the entities restarts, of sync or lose state. This could happen for example if one of the
in case of a (temporary) loss of network connectivity etc. The entities restarts, in case of a (temporary) loss of network
peering entities MUST have built-in redundancy support to recover connectivity etc. Example failure cases include the following:
state in case of failure.
Example failure cases include the following:
o NAT-controller and the DNCA Diameter peer within the NAT- o NAT-controller and the DNCA Diameter peer within the NAT-
controller lose state (e.g. due to a restart). In this case, controller lose state (e.g., due to a restart). In this case,
* the DNCA Diameter peer within the NAT-device may receive a NCR * the DNCA Diameter peer within the NAT-device MAY receive an NCR
with NC-Request-Type AVP set to INITIAL_REQUEST that matches an with NC-Request-Type AVP set to INITIAL_REQUEST that matches an
existing session of the DNCA Diameter peer within the NAT- existing session of the DNCA Diameter peer within the NAT-
device. The DNCA Diameter peer within the NAT-device returns a device. The DNCA Diameter peer within the NAT-device MUST
Result-Code that contains Duplicate-Session-Id AVP to report return Result-Code that contains Duplicate-Session-Id AVP to
the Session-ID of the existing session. The DNCA Diameter peer report the Session-ID of the existing session. The DNCA
within the NAT-controller may send an explicit Session Diameter peer within the NAT-controller MAY send an explicit
Terminate Request (STR) for the older session, which was lost. Session Terminate Request (STR) for the older session, which
was lost.
* a DNCA Diameter peer may receive accounting records for a * a DNCA Diameter peer MAY receive accounting records for a
session that does not exist. The DNCA Diameter peer sends an session that does not exist. The DNCA Diameter peer sends an
accounting answer with Result-Code set to accounting answer with Result-Code set to
DIAMETER_UNKNOWN_SESSION_ID in response. On receiving the DIAMETER_UNKNOWN_SESSION_ID in response. On receiving the
response, the DNCA Diameter peer clears the session and removes response, the DNCA Diameter peer SHOULD clear the session and
the associated session state. remove associated session state.
o NAT-device and the DNCA Diameter peer within NAT-device lose o NAT-device and the DNCA Diameter peer within NAT-device lose
state. In such a case, the DNCA Diameter peer may receive a NCR state. In such a case, the DNCA Diameter peer MAY receive a NCR
with NC-Request-Type AVP set to UPDATE_REQUEST for a non-existent with NC-Request-Type AVP set to UPDATE_REQUEST for a non-existent
session. The DNCA Diameter peer returns NCA with Result-Code set session. The DNCA Diameter peer MUST return an NCA with Result-
to DIAMETER_UNKNOWN_SESSION_ID. Code set to DIAMETER_UNKNOWN_SESSION_ID.
o The DNCA Diameter peer within the NAT-controller is unreachable, o The DNCA Diameter peer within the NAT-controller is unreachable,
for example detected by Diameter watchdog, or down and accounting for example detected by Diameter device watchdog messages (as
defined in Section 5.5 of [RFC3588]), or down and accounting
requests from the DNCA Diameter peer fail to get a response. The requests from the DNCA Diameter peer fail to get a response. The
mechanism to ensure that a DNCA Diameter peer within the NAT- mechanism to ensure that a DNCA Diameter peer within the NAT-
controller no longer has associated state for a session which was controller no longer has associated state for a session which was
cleared or removed by the DNCA Diameter peer within the NAT-device cleared or removed by the DNCA Diameter peer within the NAT-device
is beyond the scope of this document. is beyond the scope of this document.
o The DNCA Diameter peer within the NAT-device is unreachable or o The DNCA Diameter peer within the NAT-device is unreachable or
down and NCR requests fail to get a response. Handling of this down and NCR fails to get a response. Handling of this case
case depends on the actual service offering of the service depends on the actual service offering of the service provider.
provider. The service provider could for example choose to stop The service provider could for example choose to stop offering
offering connectivity service. connectivity service.
5. Use Of The Diameter Base Protocol 5. Use of the Diameter Base Protocol
The Diameter Base Protocol defined by [RFC3588] applies with the The Diameter Base Protocol defined by [RFC3588] applies with the
clarifications listed in the present specification. clarifications listed in the present specification.
5.1. Securing Diameter Messages 5.1. Securing Diameter Messages
For secure transport of Diameter messages recommendations in For secure transport of Diameter messages, the recommendations in
[RFC3588] apply. [RFC3588] apply.
DNCA Diameter peers MAY verify their identity during the Capabilities DNCA Diameter peers SHOULD verify their identity during the
Exchange Request procedure. Capabilities Exchange Request procedure.
A DNCA Diameter peer within the NAT-device MAY verify that a DNCA A DNCA Diameter peer within the NAT-device SHOULD verify that a DNCA
Diameter peer that issues a NCR command is allowed to do so based on: Diameter peer that issues a NCR command is allowed to do so based on:
o The identity of the DNCA Diameter peer o The identity of the DNCA Diameter peer
o The type of NCR Command o The type of NCR Command
o The content of the NCR Command o The content of the NCR Command
o Any combination of the above o Any combination of the above
5.2. Accounting Functionality 5.2. Accounting Functionality
Accounting functionality (accounting session state machine, related Accounting functionality (accounting session state machine, related
command codes and AVPs) is defined in Section 9 below. command codes and AVPs) is defined in Section 9 below.
5.3. Use Of Sessions 5.3. Use of Sessions
Each DNCA session MUST have a globally unique Session-ID as defined 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 in [RFC3588], which MUST NOT be changed during the lifetime of a DNCA
session. The Diameter Session-ID serves as the global endpoint session. The Diameter Session-ID serves as the global endpoint
identifier. The DNCA Diameter peers maintain state associated with identifier. The DNCA Diameter peers maintain state associated with
the Session-ID. This globally unique Session-ID is used for the Session-ID. This globally unique Session-ID is used for
updating, accounting, and terminating the session. DNCA session MUST updating, accounting, and terminating the session. A DNCA session
NOT have more than one outstanding request at any given instant. A MUST NOT have more than one outstanding request at any given instant.
DNCA Diameter peer sends an Abort-Session-Request as defined in A DNCA Diameter peer sends an Abort-Session-Request as defined in
[RFC3588] if it is unable to maintain sessions due to resource [RFC3588] if it is unable to maintain sessions due to resource
limitation. limitation.
5.4. Routing Considerations 5.4. Routing Considerations
It is assumed that the DNCA Diameter peer within a NAT-controller It is assumed that the DNCA Diameter peer within a NAT-controller
knows the DiameterIdentity of the Diameter peer within a NAT-device knows the DiameterIdentity of the Diameter peer within a NAT-device
for a given endpoint. Both the Destination-Realm and Destination- for a given endpoint. Both the Destination-Realm and Destination-
Host AVPs are present in the request from a DNCA Diameter peer within Host AVPs are present in the request from a DNCA Diameter peer within
a NAT-controller to a DNCA Diameter peer within a NAT-device. a NAT-controller to a DNCA Diameter peer within a NAT-device.
skipping to change at page 23, line 6 skipping to change at page 25, line 6
bindings. bindings.
6.1. NAT-Control Request (NCR) Command 6.1. NAT-Control Request (NCR) Command
The NAT-Control Request (NCR) command, indicated by the command field 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 set to TBD and the "R" bit set in the Command Flags field, is sent
from the DNCA Diameter peer within the NAT-controller to the DNCA from the DNCA Diameter peer within the NAT-controller to the DNCA
Diameter peer within the NAT-device in order to install NAT-bindings. Diameter peer within the NAT-device in order to install NAT-bindings.
User-Name, Logical-Access-Id, Physical-Access-ID, Framed-IP-Address, User-Name, Logical-Access-Id, Physical-Access-ID, Framed-IP-Address,
Framed-IPv6-Prefix , Framed-Interface-Id, EGRESS-VLANID, NAS-Port-ID, Framed-IPv6-Prefix, Framed-Interface-Id, EGRESS-VLANID, NAS-Port-ID,
Address-Realm, Calling-Station-ID AVPs serve as identifiers for the Address-Realm, Calling-Station-ID AVPs serve as identifiers for the
endpoint. endpoint.
Message format: Message format:
< NC-Request > ::= < Diameter Header: TBD, REQ, PXY> < NC-Request > ::= < Diameter Header: TBD, REQ, PXY>
[ Session-Id ] [ Session-Id ]
{ Auth-Application-Id } { Auth-Application-Id }
{ Origin-Host } { Origin-Host }
{ Origin-Realm } { Origin-Realm }
{ Destination-Realm } { Destination-Realm }
skipping to change at page 24, line 30 skipping to change at page 26, line 30
[ Redirect-Host-Usage ] [ Redirect-Host-Usage ]
[ Redirect-Max-Cache-Time ] [ Redirect-Max-Cache-Time ]
* [ Proxy-Info ] * [ Proxy-Info ]
* [ Route-Record ] * [ Route-Record ]
* [ Failed-AVP ] * [ Failed-AVP ]
* [ AVP ] * [ AVP ]
7. NAT Control Application Session State Machine 7. NAT Control Application Session State Machine
This section contains a set of finite state machines, representing This section contains a set of finite state machines, representing
the life cycle of DNCA session, which MUST be observed by all the life cycle of a DNCA session, which MUST be observed by all
implementations of the DNCA Diameter application. The DNCA Diameter implementations of the DNCA Diameter application. The DNCA Diameter
peers are stateful and the state machine maintained is similar to the peers are stateful and the state machine maintained is similar to the
stateful Client and Server authorization state machine described in stateful Client and Server authorization state machine described in
[RFC3588]. When a session is moved to the Idle state, any resources [RFC3588]. When a session is moved to the Idle state, any resources
that were allocated for the particular session must be released. Any that were allocated for the particular session must be released. Any
event not listed in the state machines MUST be considered as an error event not listed in the state machines MUST be considered as an error
condition, and an answer, if applicable, MUST be returned to the condition, and an answer, if applicable, MUST be returned to the
originator of the message. originator of the message.
In the state table, the event 'Failure to send NCR' means that the In the state table, the event 'Failure to send NCR' means that the
DNCA Diameter peer within the NAT-controller is unable to send the DNCA Diameter peer within the NAT-controller is unable to send the
NCR command to the desired destination. This could be due to the NCR command to the desired destination. This could be due to the
peer being down, or due to the peer sending back the transient peer being down, or due to the peer sending back the transient
failure or temporary protocol error notification DIAMETER_TOO_BUSY or failure or temporary protocol error notification DIAMETER_TOO_BUSY or
DIAMETER_LOOP_DETECTED in the Result-Code AVP of NCA. DIAMETER_LOOP_DETECTED in the Result-Code AVP of an NCA.
In the state table "FAILED NCA" means that the DNCA Diameter peer In the state table "FAILED NCA" means that the DNCA Diameter peer
within the NAT-device was not able to honor the corresponding NCR. within the NAT-device was not able to honor the corresponding NCR.
This can happen due to any transient and permanent error at the NAT- This can happen due to any transient and permanent error at the NAT-
device or its associated DNCA Diameter peer within indicated by the device or its associated DNCA Diameter peer within indicated by the
following error Result-Code values: RESOURCE_FAILURE, following error Result-Code values: RESOURCE_FAILURE,
UNKNOWN_BINDING_RULE_NAME, BINDING_FAILURE, UNKNOWN_BINDING_TEMPLATE_NAME, BINDING_FAILURE,
MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT, SESSION_EXISTS, MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT, SESSION_EXISTS,
INSUFFICIENT_CLASSIFIERS. INSUFFICIENT_CLASSIFIERS.
The following state machine is observed by a DNCA Diameter peer The following state machine is observed by a DNCA Diameter peer
within a NAT-controller. The state machine description uses the term within a NAT-controller. The state machine description uses the term
"access session" to describe the connectivity service offered to the "access session" to describe the connectivity service offered to the
endpoint or host. "Access session" should not be confused with the endpoint or host. "Access session" should not be confused with the
Diameter session ID. Diameter session ID.
DNCA Diameter peer within a NAT-controller DNCA Diameter peer within a NAT-controller
skipping to change at page 25, line 32 skipping to change at page 27, line 32
Idle ASR Received Send ASA Idle Idle ASR Received Send ASA Idle
for unknown session with for unknown session with
Result-Code Result-Code
= UNKNOWN_ = UNKNOWN_
SESSION_ID SESSION_ID
Pending Successful NCA Setup Open Pending Successful NCA Setup Open
received complete received complete
Pending Successful NCA Sent STR Discon Pending Successful NCA Send STR Discon
received received
but peer unable to provide but peer unable to provide
service service
Pending Error processing successful Sent STR Discon Pending Error processing successful Send STR Discon
NCA NCA
Pending Failed Cleanup Idle Pending Failed Clean up Idle
NCA received NCA received
Open NAT control Send Open Open NAT control Send Open
update required NCR Update update required NCR Update
Request Request
Open Successful Open Open Successful Open
NCA received NCA received
Open Failed Cleanup Idle Open Failed Clean up Idle
NCA received. NCA received
Open Access session end detected Send STR Discon Open Access session end detected Send STR Discon
Open ASR Received, Send ASA Discon Open ASR Received, Send ASA Discon
access session will be with access session will be with
terminated Result-Code terminated Result-Code
= SUCCESS, = SUCCESS,
Send STR. Send STR
Open ASR Received, Send ASA Open Open ASR Received, Send ASA Open
access session will not with access session will not with
be terminated Result-Code be terminated Result-Code
!= SUCCESS != SUCCESS
Discon ASR Received Send ASA Idle Discon ASR Received Send ASA Idle
Discon STA Received Discon. Idle Discon STA Received Discon. Idle
user/device user/device
The following state machine is observed by a DNCA Diameter peer The following state machine is observed by a DNCA Diameter peer
within a NAT-device. within a NAT-device.
DNCA Diameter peer within a NAT-device DNCA Diameter peer within a NAT-device
State Event Action New State State Event Action New State
------------------------------------------------------------- -------------------------------------------------------------
Idle NCR request Send Open Idle NCR Query request Send Idle
received, and successful received, and successful
able to provide requested NCA able to provide requested NCA
NAT Binding report
Idle NCR received Send Open
and able to successful
provide requested NCA
NAT control service NAT control service
Idle NCR request Send Idle Idle NCR request Send Idle
received, and failed received, and failed
unable to provide requested NCA unable to provide requested NCA
NAT control service NAT control service
Open NCR request Send Open Open NCR request Send Open
received, and successful received, and successful
able to provide requested NCA able to provide requested NCA
NAT control service NAT control service
Open NCR request Send Idle Open NCR request Send Idle
received, and failed received, and failed
unable to provide requested NCA, unable to provide requested NCA,
NAT control service Cleanup NAT control service Clean up
Open Unable to continue Send ASR Discon Open Unable to continue Send ASR Discon
providing requested providing requested
NAT control service NAT control service
Discon Failure to send ASR Wait, Discon Discon Failure to send ASR Wait, Discon
resend ASR resend ASR
Discon ASR successfully sent and Cleanup Idle Discon ASR successfully sent and Clean up Idle
ASA Received with Result-Code ASA Received with Result-Code
Not ASA Received None No change Not ASA Received None No change
Discon Discon
Any STR Received Send STA, Idle Any STR Received Send STA, Idle
Cleanup. Clean up
8. DNCA AVPs 8. DNCA AVPs
8.1. Reused Base Protocol AVPs 8.1. Reused Base Protocol AVPs
AVPs reused from Diameter Base Protocol [RFC3588] are listed below. The following table describes the AVPs reused from Diameter Base
Protocol [RFC3588]; their AVP Code values, types, and possible flag
+-------------------+ values; and whether the AVP MAY be encrypted.The [RFC3588] specifies
| AVP Flag rules | the AVP Flag rules for AVPs in section 4.5. The Diameter AVP rules
are defined in the [RFC3588], section 4.
+---------+
| AVP |
| Flag |
| rules |
+-----------------------------------------------|-----+---+---------+ +-----------------------------------------------|-----+---+---------+
| AVP | | | May | | AVP | | | |
| Attribute Name Code Data Type |MUST |MAY| encrypt | | Attribute Name Code Data Type |MUST |MAY| Encr |
+-----------------------------------------------+-----+---+---------+ +-----------------------------------------------+-----+---+---------+
|Acct-Interim-Interval 85 Unsigned32 | M | P | Y | |Acct-Interim-Interval 85 Unsigned32 | M | P | Y |
|Auth-Application-Id 258 Unsigned32 | M | P | N | |Auth-Application-Id 258 Unsigned32 | M | P | N |
|Destination-Host 293 DiamIdent | M | P | N | |Destination-Host 293 DiamIdent | M | P | N |
|Destination-Realm 283 DiamIdent | M | P | N | |Destination-Realm 283 DiamIdent | M | P | N |
|Error-Message 281 UTF8String | M | P | N | |Error-Message 281 UTF8String | M | P | N |
|Error-Reporting-Host 294 DiamIdent | M | P | N | |Error-Reporting-Host 294 DiamIdent | M | P | N |
|Failed-AVP 279 Grouped | M | P | N | |Failed-AVP 279 Grouped | M | P | N |
|Origin-Host 264 DiamIdent | M | P | N | |Origin-Host 264 DiamIdent | M | P | N |
|Origin-Realm 296 DiamIdent | M | P | N | |Origin-Realm 296 DiamIdent | M | P | N |
|Origin-State-Id 278 Unsigned32 | M | P | N | |Origin-State-Id 278 Unsigned32 | M | P | N |
|Proxy-Info 284 Grouped | M | P | N | |Proxy-Info 284 Grouped | M | P | N |
|Result-Code 268 Unsigned32 | M | P | N | |Result-Code 268 Unsigned32 | M | P | N |
|Route-Record 282 DiamIdent | M | | N | |Route-Record 282 DiamIdent | M | | N |
|Session-Id 263 UTF8String | M | P | Y | |Session-Id 263 UTF8String | M | P | Y |
|User-Name 1 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 | Table 1: DIAMETER AVPs used from Diameter base
| 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 10: DIAMETER AVPs used from Diameter base
The Auth-Application-Id AVP (AVP Code 258) is assigned by IANA to 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 applications. The value of the Auth-Application-Id for the
Diameter NAT Control Application is TBD. Diameter NAT Control Application is TBD.
8.2. Additional Result-Code AVP Values 8.2. Additional Result-Code AVP Values
This section defines new values for the Result-Code AVP which SHALL This section defines new values for the Result-Code AVP which SHALL
be supported by all Diameter implementations that conform to the be supported by all Diameter implementations that conform to the
present document. present document.
skipping to change at page 29, line 24 skipping to change at page 31, line 29
8.2.3. Permanent Failures 8.2.3. Permanent Failures
The Result-Code AVP values, which fall within the 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 category are used to inform the peer that the request failed, and
should not be attempted again. The request may be able to be should not be attempted again. The request may be able to be
satisfied in the future. satisfied in the future.
The following new values of the Result-Code AVP are defined: The following new values of the Result-Code AVP are defined:
UNKNOWN_BINDING_RULE_NAME (TBD) UNKNOWN_BINDING_TEMPLATE_NAME (TBD)
The DNCA Diameter peer within the NAT-device indicates that the The DNCA Diameter peer within the NAT-device indicates that the
binding could not be installed or a new session could not be binding could not be installed or a new session could not be
created because the specified NAT-Control-Binding-Rule AVP, created because the specified NAT-Control-Binding-Template AVP,
that refers to a predefined policy template in the NAT-device, that refers to a predefined policy template in the NAT-device,
is unknown. is unknown.
BINDING_FAILURE (TBD) BINDING_FAILURE (TBD)
DNCA indicates that the requested binding(s) could not be DNCA indicates that the requested binding(s) could not be
installed. For example: Requested ports are already in use. installed. For example: Requested ports are already in use.
MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT (TBD) MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT (TBD)
skipping to change at page 30, line 14 skipping to change at page 32, line 16
INSUFFICIENT_CLASSIFIERS (TBD) INSUFFICIENT_CLASSIFIERS (TBD)
The DNCA Diameter peer within the NAT-device requests to The DNCA Diameter peer within the NAT-device requests to
initialize a new session, if the classifiers in the request initialize a new session, if the classifiers in the request
match more than one of the existing sessions on the DNCA match more than one of the existing sessions on the DNCA
Diameter peer within the NAT-device. Diameter peer within the NAT-device.
8.3. Reused NASREQ Diameter Application AVPs 8.3. Reused NASREQ Diameter Application AVPs
The following AVPs are reused from Diameter Network Access Server The following table describes the AVPs reused from the Diameter
Application [RFC4005]. Network Access Server Application [RFC4005]; their AVP Code values,
types, and possible flag values; and whether the AVP MAY be
encrypted.The [RFC3588] specifies the AVP Flag rules for AVPs in
section 4.5. The Diameter AVP rules are defined in the [RFC3588],
section 4.
+---------------------+ +---------------------+
| AVP Flag rules | | AVP Flag rules |
+------------------+------+------------|----+-----+----+-----|----+ +------------------+------+------------|----+-----+----+-----|----+
| | AVP | | | |SHLD| MUST| | | | AVP | | | |SHLD| MUST| |
| Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr| | Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr|
|------------------|------|------------|----+-----+----+-----|----| |------------------|------|------------|----+-----+----+-----|----|
| NAS-Port | 5 | Unsigned32 | M | P | | V | Y | | NAS-Port | 5 | Unsigned32 | M | P | | V | Y |
| NAS-Port-Id | 87 | UTF8String | M | P | | V | Y | | NAS-Port-Id | 87 | UTF8String | M | P | | V | Y |
| Calling-Station- | 31 | UTF8String | M | P | | V | Y | | Calling-Station- | 31 | UTF8String | M | P | | V | Y |
| Id | | | | | | | | | Id | | | | | | | |
| Framed-IP-Address| 8 | OctetString| M | P | | V | Y | | Framed-IP-Address| 8 | OctetString| M | P | | V | Y |
| Framed-IP-Netmask| 9 | OctetString| M | P | | V | Y |
| Framed-Interface-| 96 | Unsigned64 | M | P | | V | Y | | Framed-Interface-| 96 | Unsigned64 | M | P | | V | Y |
| Id | | | | | | | | | Id | | | | | | | |
| Framed-IPv6- | 97 | OctetString| M | P | | V | Y | | Framed-IPv6- | 97 | OctetString| M | P | | V | Y |
| Prefix | | | | | | | | | Prefix | | | | | | | |
+------------------+------+------------|----+-----+----+-----|----+ +------------------+------+------------|----+-----+----+-----|----+
Table 2: Reused NASREQ Diameter application AVPs
Figure 11: Reused NASREQ Diameter application AVPs
8.4. Reused AVPs from RFC 4675 8.4. Reused AVPs from RFC 4675
The following AVPs are reused from "RADIUS Attributes for Virtual LAN The following table describes the AVPs reused from "RADIUS Attributes
and Priority Support" specification [RFC4675]. for Virtual LAN and Priority Support" specification [RFC4675]; their
AVP Code values, types, and possible flag values; and whether the AVP
MAY be encrypted.The [RFC3588] specifies the AVP Flag rules for AVPs
in section 4.5. The Diameter AVP rules are defined in the [RFC3588],
section 4.
+---------------------+ +---------------------+
| AVP Flag rules | | AVP Flag rules |
+------------------+------+------------|----+-----+----+-----|----+ +------------------+------+------------|----+-----+----+-----|----+
| | AVP | | | |SHLD| MUST| | | | AVP | | | |SHLD| MUST| |
| Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr| | Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr|
|------------------|------|------------|----+-----+----+-----|----| |------------------|------|------------|----+-----+----+-----|----|
| Egress-VLANID | 56 | OctetString| M | P | | V | Y | | Egress-VLANID | 56 | OctetString| M | P | | V | Y |
+------------------+------+------------|----+-----+----+-----|----+ +------------------+------+------------|----+-----+----+-----|----+
Table 3: Reused attributes from RFC 4675
Figure 12: Reused attributes from RFC 4675
8.5. Reused AVPs from Diameter QoS Application 8.5. Reused AVPs from Diameter QoS Application
The following AVPs are reused from the Traffic Classification and The following table describes the AVPs reused from the Traffic
Quality of Service (QoS) Attributes for Diameter [RFC5777]. Classification and Quality of Service (QoS) Attributes for Diameter
+-------------------+ [RFC5777]; their AVP Code values, types, and possible flag values;
| AVP Flag rules | and whether the AVP MAY be encrypted.The [RFC3588] specifies the AVP
Flag rules for AVPs in section 4.5. The Diameter AVP rules are
defined in the [RFC3588], section 4.
+---------+
| AVP |
| Flag |
| rules |
+-----------------------------------------------|-----+---+---------+ +-----------------------------------------------|-----+---+---------+
| AVP | | | May | | AVP | | | |
| Attribute Name Code Data Type |MUST |MAY| encrypt | | Attribute Name Code Data Type |MUST |MAY| Encr |
+-----------------------------------------------+-----+---+---------+ +-----------------------------------------------+-----+---+---------+
|Port TBD Integer32 | M | P | Y | |Port 530 Integer32 | M | P | Y |
|IP-Address-Mask TBD Grouped | M | P | Y | |Protocol 513 Enumerated | M | P | Y |
|Protocol TBD Enumerated | M | P | Y | |Direction 514 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 13: Reused QoS-attributes Table 4: Reused QoS-attributes
8.6. Reused AVPs from ETSI ES 283 034, e4 Diameter Application 8.6. Reused AVPs from ETSI ES 283 034, e4 Diameter Application
The following AVPs are reused from the Diameter e4 Application The following table describes the AVPs reused from the Diameter e4
[ETSIES283034]. Application [ETSIES283034]; their AVP Code values, types, and
+-------------------+ possible flag values; and whether the AVP MAY be encrypted.The
| AVP Flag rules | [RFC3588] specifies the AVP Flag rules for AVPs in section 4.5. The
Diameter AVP rules are defined in the [RFC3588], section 4. The
Vendor-ID field in these AVP header will be set to ETSI (13019).
+---------+
| AVP |
| Flag |
| rules |
+-----------------------------------------------|-----+---+---------+ +-----------------------------------------------|-----+---+---------+
| AVP | | | May | | AVP | | | |
| Attribute Name Code Data Type |MUST |MAY| encrypt | | Attribute Name Code Data Type |MUST |MAY| Encr |
+-----------------------------------------------+-----+---+---------+ +-----------------------------------------------+-----+---+---------+
|Address-Realm 301 OctetString | M,V | | Y | |Address-Realm 301 OctetString | M,V | | Y |
|Logical-Access-Id 302 OctetString | V | M | Y | |Logical-Access-Id 302 OctetString | V | M | Y |
|Physical-Access-ID 313 UTF8String | 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 14: Reused AVPs from Diameter e4 application Table 5: Reused AVPs from Diameter e4 application
8.7. DNCA Defined AVPs 8.7. DNCA Defined AVPs
The following table describes the new Diameter AVPs used in this The following table describes the new Diameter AVPs defined in this
document. document; their AVP Code values, types, and possible flag values; and
+-------------------+ whether the AVP MAY be encrypted.The [RFC3588] specifies the AVP Flag
| AVP Flag rules | rules for AVPs in section 4.5. The Diameter AVP rules are defined in
the [RFC3588], section 4. The AVPs defined here MUST NOT have the V
bit in the AVP Flag set.
+---------+
| AVP |
| Flag |
| rules |
+-----------------------------------------------|-----+---+---------+ +-----------------------------------------------|-----+---+---------+
| AVP Section | | | May | | AVP | | | |
| Attribute Name Code Defined Data Type |MUST |MAY| encrypt | | Attribute Name Code Data Type |MUST |MAY| Encr |
+-----------------------------------------------+-----+---+---------+ +-----------------------------------------------+-----+---+---------+
|NC-Request-Type TBD 8.7.1 Enumerated | M | P | Y | |NC-Request-Type TBD 8.7.1 Enumerated | M | P | Y |
|NAT-Control-Install TBD 8.7.2 Grouped | M | P | Y | |NAT-Control-Install TBD 8.7.2 Grouped | M | P | Y |
|NAT-Control-Remove TBD 8.7.3 Grouped | M | P | Y | |NAT-Control-Remove TBD 8.7.3 Grouped | M | P | Y |
|NAT-Control-Definition TBD 8.7.4 Grouped | M | P | Y | |NAT-Control-Definition TBD 8.7.4 Grouped | M | P | Y |
|NAT-Internal-Address TBD 8.7.5 Grouped | M | P | Y | |NAT-Internal-Address TBD 8.7.5 Grouped | M | P | Y |
|NAT-External-Address TBD 8.7.6 Grouped | M | P | Y | |NAT-External-Address TBD 8.7.6 Grouped | M | P | Y |
|Max-NAT-Bindings TBD 8.7.7 Unsigned32 | M | P | Y | |Max-NAT-Bindings TBD 8.7.7 Unsigned32 | M | P | Y |
|NAT-Control- TBD 8.7.8 OctetString| M | P | Y | |NAT-Control- TBD 8.7.8 OctetString| M | P | Y |
| Binding-Rule | | | | | Binding-Template | | | |
|Duplicate- TBD 8.7.9 UTF8String | M | P | Y | |Duplicate- TBD 8.7.9 UTF8String | M | P | Y |
| Session-ID | | | | | Session-ID | | | |
|NAT-External-Port- TBD 8.7.10 Enumerated | M | P | Y |
| Style | | | |
|NAT-Control-Record TBD 9.2.1 Grouped | M | P | Y | |NAT-Control-Record TBD 9.2.1 Grouped | M | P | Y |
|NAT-Control- TBD 9.2.2 Enumerated | M | P | Y | |NAT-Control- TBD 9.2.2 Enumerated | M | P | Y |
| Binding-Status | | | | | Binding-Status | | | |
|Current-NAT-Bindings TBD 9.2.3 Unsigned32 | M | P | Y | |Current-NAT-Bindings TBD 9.2.3 Unsigned32 | M | P | Y |
+-----------------------------------------------+-----+---+---------+ +-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
+-------------------------------------------------------------------+
Figure 15: New Diameter AVPs Table 6: New Diameter AVPs
8.7.1. NC-Request-Type AVP 8.7.1. NC-Request-Type AVP
The NC-Request-Type AVP (AVP Code TBD) is of type Enumerated and The NC-Request-Type AVP (AVP Code TBD) is of type Enumerated and
contains the reason for sending the NAT-Control-Request command. It contains the reason for sending the NAT-Control-Request command. It
shall be present in all NAT-Control-Request messages. shall be present in all NAT-Control-Request messages.
The following values are defined: The following values are defined:
INITIAL_REQUEST (1) INITIAL_REQUEST (1)
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QUERY_REQUEST (3) QUERY_REQUEST (3)
Query Request is used to query a NAT-device about the currently Query Request is used to query a NAT-device about the currently
installed bindings for an endpoint classifier. installed bindings for an endpoint classifier.
8.7.2. NAT-Control-Install AVP 8.7.2. NAT-Control-Install AVP
The NAT-Control AVP (AVP code TBD) is of type Grouped, and it is used 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- to activate or install NAT bindings. It also contains Max-NAT-
Bindings that defines the maximum number of NAT bindings to be Bindings that defines the maximum number of NAT bindings allowed for
allowed for a subscriber and the NAT-Control-Binding-Rule that an end point and the NAT-Control-Binding-Template that references a
references a predefined policy template on the NAT-device that may predefined template on the NAT-device that may contain static
contain static binding, a maximum number of bindings allowed, an IP- binding, a maximum number of bindings allowed, an IP-address pool
address pool from which external binding addresses should be from which external binding addresses should be allocated, etc. If
allocated. the NAT-External-Port-Style AVP is present, then the NAT-device MUST
select the external ports for the NAT-Bindings as per the style
specified. The NAT-External-Port-Style is applicable for NAT-
Bindings defined by the NAT-Control-Definition AVPs whose NAT-
External-Address or Port AVPs within the NAT-External-Address are
unspecified.
AVP format: AVP format:
NAT-Control-Install ::= < AVP Header: TBD > NAT-Control-Install ::= < AVP Header: TBD >
* [ NAT-Control-Definition ] * [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ] [ NAT-Control-Binding-Template ]
[ Max-NAT-Bindings] [ Max-NAT-Bindings ]
[ NAT-External-Port-Style ]
* [ AVP ] * [ AVP ]
8.7.3. NAT-Control-Remove AVP 8.7.3. NAT-Control-Remove AVP
The NAT-Control-Remove AVP (AVP code TBD) is of type Grouped, and it The NAT-Control-Remove AVP (AVP code TBD) is of type Grouped, and it
is used to deactivate or remove NAT-bindings. is used to deactivate or remove NAT-bindings. At least one of the
two AVPs (NAT-Control-Definition AVP, NAT-Control-Binding-Template
AVP) SHOULD be present in the NAT-Control-Remove AVP.
AVP format: AVP format:
NAT-Control-Remove ::= < AVP Header: TBD > NAT-Control-Remove ::= < AVP Header: TBD >
* [ NAT-Control-Definition ] * [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ] [ NAT-Control-Binding-Template ]
* [ AVP ] * [ AVP ]
8.7.4. NAT-Control-Definition AVP 8.7.4. NAT-Control-Definition AVP
The NAT-Control-Definition AVP (AVP code TBD) is of type Grouped, and The NAT-Control-Definition AVP (AVP code TBD) is of type Grouped, and
it describes a binding. it describes a binding.
The NAT-Control-Definition AVP uniquely identifies the binding The NAT-Control-Definition AVP uniquely identifies the binding
between the DNCA Diameter peers. between the DNCA Diameter peers.
If both the NAT-Internal-Address and NAT-External-Address AVP(s) are If both the NAT-Internal-Address and NAT-External-Address AVP(s) are
supplied, it is a pre-defined binding. supplied, it is a pre-defined binding.
If the NAT-External-Address AVP is not specified then the NAT-device
MUST select the external port as per the NAT-External-Port-Style AVP,
if present in the NAT-Control-Definition AVP.
The Protocol AVP describes the transport protocol for the binding. The Protocol AVP describes the transport protocol for the binding.
The NAT-Control-Definition AVP can contain either zero or one The NAT-Control-Definition AVP can contain either zero or one
Protocol AVP. If the Protocol AVP is omitted and if both internal Protocol AVP. If the Protocol AVP is omitted and if both internal
and external IP-address are specified then the binding reserves the and external IP-address are specified then the binding reserves the
IP-addresses for all transport protocols. IP-addresses for all transport protocols.
The Direction AVP is of type Enumerated. It specifies the direction The Direction AVP is of type Enumerated. It specifies the direction
for the binding. The values of the enumeration applicable in this for the binding. The values of the enumeration applicable in this
context are: "IN","OUT". If Direction AVP is OUT or absent, the NAT- context are: "IN","OUT". If Direction AVP is OUT or absent, the NAT-
Internal-Address refers to the IP-address of the endpoint that needs Internal-Address refers to the IP-address of the endpoint that needs
skipping to change at page 34, line 44 skipping to change at page 37, line 51
AVP format: AVP format:
NAT-Internal-Address ::= < AVP Header: TBD > NAT-Internal-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ] [ Framed-IP-Address ]
[ Framed-IPv6-Prefix ] [ Framed-IPv6-Prefix ]
[ Port] [ Port]
* [ AVP ] * [ AVP ]
8.7.6. NAT-External-Address AVP 8.7.6. NAT-External-Address AVP
The NAT-External-Address AVP (AVP code TBD) is of type Grouped, and 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- it describes the external IP-address and port for a binding. Framed-
Address-Mask AVP can only be specified when the Framed-IP-Address AVP IP-Netmask AVP can only be specified when the Framed-IP-Address AVP
is present. The external IP-address specified in this attribute can is present. The external IP-address specified in this attribute can
be reused for multiple endpoints by specifying the same address in be reused for multiple endpoints by specifying the same address in
the respective NAT-External-Address AVPs. the respective NAT-External-Address AVPs. If the external IP-address
is not specified and the NAT-External-Port-Style AVP is specified in
the NAT-Control-Definition AVP then the NAT-device MUST select
external port as per the NAT-External-Port-Style AVP.
AVP format: AVP format:
NAT-External-Address ::= < AVP Header: TBD > NAT-External-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ] [ Framed-IP-Address ]
[ IP-Address-Mask ] [ Framed-IP-Netmask ]
[ Port ] [ Port ]
* [ AVP ] * [ AVP ]
8.7.7. Max-NAT-Bindings 8.7.7. Max-NAT-Bindings
The Max-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32. It The Max-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32. It
indicates the maximum number of NAT-bindings allowed for a particular indicates the maximum number of NAT-bindings allowed for a particular
endpoint. endpoint.
8.7.8. NAT-Control-Binding-Rule AVP 8.7.8. NAT-Control-Binding-Template AVP
The NAT-Control-Binding-Rule AVP (AVP code TBD) is of type The NAT-Control-Binding-Template AVP (AVP code TBD) is of type
OctetString. It defines a name for a policy template that is OctetString. It defines a name for a policy template that is
predefined at the NAT-device. Details on the contents and structure predefined at the NAT-device. Details on the contents and structure
of the template and configuration are outside the scope of this of the template and configuration are outside the scope of this
document. The policy to which this AVP refers to may contain NAT- document. The policy to which this AVP refers to may contain NAT-
bindings, IP-address pool for allocating the external IP-address of a bindings, IP-address pool for allocating the external IP-address of a
NAT-binding, and maximum number of allowed NAT-bindings. Such policy NAT-binding, and maximum number of allowed NAT-bindings. Such policy
template can be reused by specifying the same NAT-Control-Binding- template can be reused by specifying the same NAT-Control-Binding-
Rule AVP in the corresponding NAT-Control-Install AVPs of multiple Template AVP in the corresponding NAT-Control-Install AVPs of
endpoints. multiple endpoints.
8.7.9. Duplicate-Session-Id AVP 8.7.9. Duplicate-Session-Id AVP
The Duplicate-Session-Id AVP (AVP Code TBD) is of type UTF8String. The Duplicate-Session-Id AVP (AVP Code TBD) is of type UTF8String.
It is used to report errors and contains the Session-Id of an It is used to report errors and contains the Session-Id of an
existing session. existing session.
8.7.10. NAT-External-Port-Style AVP
The NAT-External-Port-Style AVP (AVP Code TBD) is of type Enumerated
and contains the style to be followed while selecting the external
port for a NAT-Binding relative to the internal port.
The following values are defined:
FOLLOW_INTERNAL_PORT_STYLE (1)
External port numbers selected MUST follow the same sequence
and oddity as the internal ports of the NAT-bindings. The port
odditity is required to support protocols like RTP and RTCP as
defined in [RFC3550]. If for example the internal port in a
requested NAT-binding is odd numbered then the external port
allocated MUST also be odd numbered, and vice versa for an even
numbered port. In addition, the sequence of port numbering is
maintained: If internal ports are consecutive, then the NAT-
device MUST choose consecutive external ports for the NAT-
bindings.
9. Accounting Commands 9. Accounting Commands
The DNCA reuses session based accounting as defined in the Diameter The DNCA reuses session based accounting as defined in the Diameter
Base Protocol[RFC3588] to report the bindings per endpoint. This Base Protocol[RFC3588] to report the bindings per endpoint. This
reporting is achieved by sending Diameter Accounting Requests (ACR) reporting is achieved by sending Diameter Accounting Requests (ACR)
[Start, Interim and Stop] from the DNCA Diameter peer within the NAT- [Start, Interim and Stop] from the DNCA Diameter peer within the NAT-
device to its associated DNCA Diameter peer within the NAT- device to its associated DNCA Diameter peer within the NAT-
controller. controller.
The DNCA Diameter peer within the NAT-device sends an ACR Start on The DNCA Diameter peer within the NAT-device sends an ACR Start on
skipping to change at page 36, line 12 skipping to change at page 39, line 42
Request-Type AVP set to UPDATE_REQUEST, or periodically as specified Request-Type AVP set to UPDATE_REQUEST, or periodically as specified
in Acct-Interim-Interval by the DNCA Diameter peer within the NAT- in Acct-Interim-Interval by the DNCA Diameter peer within the NAT-
controller, or when it creates or tears down bindings. An ACR Stop controller, or when it creates or tears down bindings. An ACR Stop
is sent by the DNCA Diameter peer within the NAT-device on receiving is sent by the DNCA Diameter peer within the NAT-device on receiving
STR. STR.
The function of correlating the multiple bindings used by an endpoint The function of correlating the multiple bindings used by an endpoint
at any given time is relegated to the post processor. at any given time is relegated to the post processor.
The DNCA Diameter peer within the NAT-device may trigger an interim The DNCA Diameter peer within the NAT-device may trigger an interim
accounting record when maximum number of bindings, if received in accounting record when the maximum number of bindings, if received in
NCR, is reached. an NCR, is reached.
9.1. NAT Control Accounting Messages 9.1. NAT Control Accounting Messages
The ACR and ACA messages are reused as defined in Diameter Base The ACR and ACA messages are reused as defined in the Diameter Base
Protocol [RFC3588] for exchanging endpoint NAT binding details Protocol [RFC3588] for exchanging endpoint NAT binding details
between the DNCA Diameter peers. DNCA Application ID is used in the between the DNCA Diameter peers. The DNCA Application IDs is used in
accounting commands. ACR contains one or more optional NAT-Control- the accounting commands. ACR contains one or more optional NAT-
Record AVP to report the bindings. The NAT-device indicates the Control-Record AVPs to report the bindings. The NAT-device indicates
number of allocated NAT bindings to NAT-controller using the Current- the number of allocated NAT bindings to the NAT-controller using the
NAT-Bindings AVP. This number needs to match the number of bindings Current-NAT-Bindings AVP. This number needs to match the number of
identified as active within the NAT-Control-Record AVP. bindings identified as active within the NAT-Control-Record AVP.
9.2. NAT Control Accounting AVPs 9.2. NAT Control Accounting AVPs
In addition to AVPs for ACR specified in [RFC3588], the DNCA Diameter In addition to AVPs for ACR specified in [RFC3588], the DNCA Diameter
peer within the NAT-device must add the NAT-Control-Record AVP. peer within the NAT-device must add the NAT-Control-Record AVP.
9.2.1. NAT-Control-Record 9.2.1. NAT-Control-Record
The NAT-Control-Record AVP (AVP code TBD) is of type Grouped. It 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 describes a binding and its status. If NAT-Control-Binding-Status is
skipping to change at page 37, line 20 skipping to change at page 40, line 50
NAT binding is active. NAT binding is active.
Removed (3) Removed (3)
NAT binding was removed. NAT binding was removed.
9.2.3. Current-NAT-Bindings 9.2.3. Current-NAT-Bindings
The Current-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32. The Current-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32.
It indicates number of NAT bindings active on NAT-device. It indicates the number of NAT bindings active on the NAT-device.
10. AVP Occurrence Table 10. AVP Occurrence Table
The following sections presents the AVPs defined in this document and The following sections present the AVPs defined in this document and
specifies the Diameter messages in which, they MAY be present. Note: specify the Diameter messages in which they can be present. Note:
AVPs that can only be present within a Grouped AVP are not AVPs that can only be present within a Grouped AVP are not
represented in this table. represented in this table.
The table uses the following symbols: The table uses the following symbols:
0 The AVP MUST NOT be present in the message. 0 The AVP MUST NOT be present in the message.
0+ Zero or more instances of the AVP MAY be present in the 0+ Zero or more instances of the AVP can be present in the
message. message.
0-1 Zero or one instance of the AVP MAY be present in the 0-1 Zero or one instance of the AVP can be present in the
message. It is considered an error if there is more message. It is considered an error if there is more
than one instance of the AVP. than one instance of the AVP.
1 One instance of the AVP MUST be present in the message. 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 1+ At least one instance of the AVP MUST be present in the
message. message.
10.1. DNCA AVP Table for NAT Control Initial and Update Requests 10.1. DNCA AVP Table for NAT Control Initial and Update Requests
The following table lists DNCA specific AVPs that have to be present The following table lists DNCA specific AVPs that have to be present
in NCR and NCA with NC-Request-Type set to INITIAL_REQUEST or in NCRs and NCAs with NC-Request-Type set to INITIAL_REQUEST or
UPDATE_REQUEST. UPDATE_REQUEST.
+-------------------+ +-------------------+
| Command Code | | Command Code |
+-----------------------------------+-------------------+ +-----------------------------------+-------------------+
| Attribute Name NCR NCA | | Attribute Name NCR NCA |
+-------------------------------------------------------+ +-------------------------------------------------------+
|NC-Request-Type 1 1 | |NC-Request-Type 1 1 |
|NAT-Control-Install 0-1 0 | |NAT-Control-Install 0-1 0 |
|NAT-Control-Remove 0-1 0 | |NAT-Control-Remove 0-1 0 |
|NAT-Control-Definition 0 0 | |NAT-Control-Definition 0 0 |
|Current-NAT-Bindings 0 0 | |Current-NAT-Bindings 0 0 |
skipping to change at page 38, line 18 skipping to change at page 41, line 46
| Attribute Name NCR NCA | | Attribute Name NCR NCA |
+-------------------------------------------------------+ +-------------------------------------------------------+
|NC-Request-Type 1 1 | |NC-Request-Type 1 1 |
|NAT-Control-Install 0-1 0 | |NAT-Control-Install 0-1 0 |
|NAT-Control-Remove 0-1 0 | |NAT-Control-Remove 0-1 0 |
|NAT-Control-Definition 0 0 | |NAT-Control-Definition 0 0 |
|Current-NAT-Bindings 0 0 | |Current-NAT-Bindings 0 0 |
|Duplicate-Session-Id 0 0-1 | |Duplicate-Session-Id 0 0-1 |
+-------------------------------------------------------+ +-------------------------------------------------------+
Note that any combination of "NAT-Control-Install" and "NAT-Control-
Remove" AVPs could be present in an update or initial requests.
Consider the following examples:
Neither "NAT-Control-Install AVP" nor "NAT-Control-Remove AVP" are
present: This could for example be the case if the NAT-controller
would only want to receive accounting information, but not control
NAT-bindings.
Only "NAT-Control-Install AVP" is present: This could for example
be the case if a new NAT-binding is installed for an existing
session.
Only "NAT-Control-Remove AVP" is present: This could for example
be the case if a new NAT-binding is removed from an existing
session.
Both, "NAT-Control-Install AVP" and "NAT-Control-Remove AVP" are
present: This could for example be the case if a formerly created
NAT-binding is removed and a new NAT-binding is established within
the same request.
10.2. DNCA AVP Table for Session Query request 10.2. DNCA AVP Table for Session Query request
The following table lists DNCA specific AVPs that have to be present The following table lists DNCA specific AVPs that have to be present
in NCR and NCA with NC-Request-Type set to QUERY_REQUEST. in NCRs and NCAs with NC-Request-Type set to QUERY_REQUEST.
+-------------------+ +-------------------+
| Command Code | | Command Code |
+-----------------------------------+-------------------+ +-----------------------------------+-------------------+
| Attribute Name NCR NCA | | Attribute Name NCR NCA |
+-------------------------------------------------------+ +-------------------------------------------------------+
|NC-Request-Type 1 1 | |NC-Request-Type 1 1 |
|NAT-Control-Install 0 0 | |NAT-Control-Install 0 0 |
|NAT-Control-Remove 0 0 | |NAT-Control-Remove 0 0 |
|NAT-Control-Definition 0 0+ | |NAT-Control-Definition 0 0+ |
|Current-NAT-Bindings 0 1 | |Current-NAT-Bindings 0 1 |
skipping to change at page 39, line 27 skipping to change at page 43, line 32
11.2. Command Codes 11.2. Command Codes
This specification uses the value <TBD> from the Command code This specification uses the value <TBD> from the Command code
namespace defined in [RFC3588] for the NAT-Control-Request (NCR), namespace defined in [RFC3588] for the NAT-Control-Request (NCR),
NAT-Control-Answer (NCA) commands. See Section 6.1 and Section 6.2 NAT-Control-Answer (NCA) commands. See Section 6.1 and Section 6.2
for more information on these commands. for more information on these commands.
11.3. AVP Codes 11.3. AVP Codes
This specification assigns the values <TBD> from the AVP code This specification assigns the values <TBD> from the AVP code
namespace defined in [RFC3588]. See Figure 15for the assignment of namespace defined in [RFC3588]. See Section 8.7 for the assignment
the namespace in this specification. of the namespace in this specification.
11.4. Result-Code AVP Values 11.4. Result-Code AVP Values
This specification assigns the values <TBD> (4xxx, 5xxx, 5xxx, 5xxx, This specification assigns the values <TBD> (4xxx, 5xxx, 5xxx, 5xxx,
5xxx,5xxx) from the Result-Code AVP value namespace defined in 5xxx,5xxx) from the Result-Code AVP value namespace defined in
[RFC3588]. See Section 8.2 for the assignment of the namespace in [RFC3588]. See Section 8.2 for the assignment of the namespace in
this specification. this specification.
11.5. NC-Request-Type AVP 11.5. NC-Request-Type AVP
As defined in Section 8.7.1, the NC-Request-Type AVP includes As defined in Section 8.7.1, the NC-Request-Type AVP includes
Enumerated type values 1 - 3. IANA has created and is maintaining a Enumerated type values 1 - 3. IANA has created and is maintaining a
namespace for this AVP. All remaining values are available for namespace for this AVP. All remaining values are available for
assignment by a Designated Expert [RFC5226]. assignment by a Designated Expert [RFC5226].
11.6. NAT-Control-Binding-Status AVP 11.6. NAT-External-Port-Style AVP
As defined in Section 8.7.10, the NAT-External-Port-Style AVP
includes Enumerated type value 1. IANA has created and is
maintaining a namespace for this AVP. All remaining values are
available for assignment by a Designated Expert [RFC5226].
11.7. NAT-Control-Binding-Status AVP
As defined in Section 8.7.1, the NAT-Control-Binding-Status AVP As defined in Section 8.7.1, the NAT-Control-Binding-Status AVP
includes Enumerated type values 1 - 3. IANA has created and is includes Enumerated type values 1 - 3. IANA has created and is
maintaining a namespace for this AVP. All remaining values are maintaining a namespace for this AVP. All remaining values are
available for assignment by a Designated Expert [RFC5226]. available for assignment by a Designated Expert [RFC5226].
12. Security Considerations 12. Security Considerations
This document describes procedures for controlling NAT related This document describes procedures for controlling NAT related
attributes and parameters by an entity, which is non-local to the attributes and parameters by an entity, which is non-local to the
device performing NAT. This section discusses security device performing NAT. This section discusses security
considerations for DNCA. This includes the interactions between the considerations for DNCA. This includes the interactions between the
Diameter peers within a NAT-controller and a NAT-device as well as Diameter peers within a NAT-controller and a NAT-device as well as
general considerations for NAT-control in a service provider network. general considerations for NAT-control in a service provider network.
Security between NAT-controller and NAT-device has a number of Security between a NAT-controller and a NAT-device has a number of
components: authentication, authorization, integrity, and components: authentication, authorization, integrity, and
confidentiality. confidentiality.
Authentication refers to confirming the identity of an originator for Authentication refers to confirming the identity of an originator for
all datagrams received from the originator. Lack of authentication all datagrams received from the originator. Lack of authentication
of Diameter messages between the Diameter peers can jeopardize the of Diameter messages between the Diameter peers can jeopardize the
fundamental service of the peering network elements. A consequence fundamental service of the peering network elements. A consequence
of not authenticating the message sender by the recipient would be of not authenticating the message sender by the recipient would be
that an attacker could spoof the identity of a "legitimate" that an attacker could spoof the identity of a "legitimate"
authorizing entity in order to change the behavior of the receiver. authorizing entity in order to change the behavior of the receiver.
An attacker could for example launch a denial of service attack by An attacker could for example launch a denial of service attack by
setting the maximum number of bindings for a session on the NAT- setting the maximum number of bindings for a session on the NAT-
device to zero; provision bindings on a NAT-device which include IP- device to zero; provision bindings on a NAT-device which include IP-
addresses already in use in other parts of the network; or request addresses already in use in other parts of the network; or request
session termination of the Diameter session and hamper a user's session termination of the Diameter session and hamper a user's
connectivity. Lack of authentication of a NAT-device to a NAT- connectivity. Lack of authentication of a NAT-device to a NAT-
controller could lead to situations where the NAT-device could controller could lead to situations where the NAT-device could
provide a wrong view of the resources (i.e. NAT-bindings). In provide a wrong view of the resources (i.e. NAT-bindings). In
addition, templates on the NAT-device specifying pre-defined binding addition, NAT Binding Predefined template on the NAT-device could be
rules could be configured differently than expected by the NAT- configured differently than expected by the NAT-controller. Failing
controller. Failing of any of the two DNCA Diameter peers to provide of any of the two DNCA Diameter peers to provide the required
the required credentials should be subject to logging. credentials should be subject to logging. The corresponding logging
infrastructure of the operator SHOULD be built in a way that it can
mitigate potential denial of service attacks resulting from large
amounts of logging events. This could include proper dimensioning of
the logging infrastructure combined with policing the maximum amount
of logging events accepted by the logging system to a threshold which
the system is known to be able to handle.
Authorization refers to whether a particular authorizing entity is Authorization refers to whether a particular authorizing entity is
authorized to signal a network element requests for one or more authorized to signal a network element requests for one or more
applications, adhering to a certain policy profile. Failing the applications, adhering to a certain policy profile. Failing the
authorization process might indicate a resource theft attempt or authorization process might indicate a resource theft attempt or
failure due to administrative and/or credential deficiencies. In failure due to administrative and/or credential deficiencies. In
either case, the network element should take the proper measures to either case, the network element should take the proper measures to
log such attempts. log such attempts.
Integrity is required to ensure that a Diameter message exchanged Integrity is required to ensure that a Diameter message exchanged
skipping to change at page 41, line 14 skipping to change at page 45, line 31
Confidentiality protection of Diameter messages ensures that the Confidentiality protection of Diameter messages ensures that the
signaling data is accessible only to the authorized entities. When signaling data is accessible only to the authorized entities. When
signaling messages between the DNCA Diameter peers traverse untrusted signaling messages between the DNCA Diameter peers traverse untrusted
networks, lack of confidentiality will allow eavesdropping and networks, lack of confidentiality will allow eavesdropping and
traffic analysis. traffic analysis.
Diameter offers security mechanisms to deal with the functionality Diameter offers security mechanisms to deal with the functionality
demanded above. DNCA makes use of the capabilities offered by demanded above. DNCA makes use of the capabilities offered by
Diameter and the underlying transport protocols to deliver these Diameter and the underlying transport protocols to deliver these
requirements (see Section 5.1 ). If the DNCA communication traverses requirements (see Section 5.1). If the DNCA communication traverses
untrusted networks, it is assumed that messages between DNCA Diameter untrusted networks, messages between DNCA Diameter peers SHOULD be
peers are secured using either IPsec or TLS. Please refer to secured using either IPsec or TLS. Please refer to [RFC3588],
[RFC3588], section 13 for details. DNCA Diameter peers MAY perform section 13 for details. DNCA Diameter peers SHOULD perform bilateral
bilateral authentication, authorization as well as procedures to authentication, authorization as well as procedures to ensure
ensure integrity and confidentiality of the information exchange. integrity and confidentiality of the information exchange.
It is assumed that the DNCA Diameter peers are typically in the same DNCA Diameter peers SHOULD have a mutual trust setup. This document
domain and have a mutual trust set up. This document does not does not specify a mechanisms for authorization between the DNCA
specify a mechanisms for authorization between the DNCA Diameter Diameter peers. The DNCA Diameter peers SHOULD be provided with
peers. It is assumed that the DNCA Diameter peers are provided with
sufficient information to make an authorization decision. The sufficient information to make an authorization decision. The
information can come from various sources, for example the peering information can come from various sources, for example the peering
devices could store local authentication policy, listing the devices could store local authentication policy, listing the
identities of authorized peers. identities of authorized peers.
Any mechanism or protocol providing control of a NAT-device, and DNCA Any mechanism or protocol providing control of a NAT-device, and DNCA
is an example of such a control mechanism, could allow for misuse of is an example of such a control mechanism, could allow for misuse of
the NAT-device given that it enables the definition of per- the NAT-device given that it enables the definition of per-
destination or per-source rules. Misuse could include anti- destination or per-source rules. Misuse could include anti-
competitive practices among providers, censorship, crime, etc. NAT- competitive practices among providers, censorship, crime, etc. NAT-
control could be used as a tool for preventing or redirecting access control could be used as a tool for preventing or redirecting access
to particular sites. For instance, by controlling the NAT bindings, to particular sites. For instance, by controlling the NAT bindings,
one could ensure that end points aren't able to receive particular one could ensure that end points aren't able to receive particular
flows, or that those flows are redirected to a relay that snoops or flows, or that those flows are redirected to a relay that snoops or
tampers with traffic instead of directly forwarding the traffic to tampers with traffic instead of directly forwarding the traffic to
the intended end point. In addition one could setup a binding in a the intended end point. In addition one could set up a binding in a
way that the source IP address used is one of a relay so that traffic way that the source IP address used is one of a relay so that traffic
coming back can be snooped on or interfered with. The protections on coming back can be snooped on or interfered with. The protections on
DNCA and its Diameter protocol exchanges don't prevent such abuses of DNCA and its Diameter protocol exchanges don't prevent such abuses of
NAT-control. A service provider deploying DNCA needs to make sure NAT-control. A service provider deploying DNCA needs to make sure
that higher layer processes and procedures are put in place which that higher layer processes and procedures are put in place which
allow them to detect and mitigate misuses. allow them to detect and mitigate misuses.
13. Acknowledgements 13. Examples
The authors would like to thank Wesley Eddy, Miguel A. Garcia, Jouni This section shows example DNCA message content and exchange.
Korhonen, Matt Lepinski, Avi Lior, Chris Metz, Pallavi Mishra, Lionel
Morand, Hannes Tschofenig, Shashank Vikram, Greg Weber, and Glen Zorn
for their input on this document.
14. Change History (to be removed prior to publication as an RFC) 13.1. DNCA Session Establishment Example
Figure 15 depicts a typical call flow for DNCA session establishment.
In this example, the NAT-controller:
a. requests a maximum of 100 NAT-bindings for the end point.
b. defines a static binding for a TCP connection which associates
the internal IP-Address:Port 192.0.2.1:80 with the external IP-
Address:Port 198.51.100.1:80 for the end point.
c. requests the use of a preconfigured template called "local-
policy" while creating NAT-bindings for the end point.
end point NAT-Controller (within NAS) NAT-device
| | |
| | |
| 1. Trigger | |
|--------------------------->| |
| +-------------------------------------+ |
| | 2. Determine that NAT control | |
| | is required for the end point | |
| +-------------------------------------+ |
| | |
| | |
| ...................................
| .| 3. Diameter Base CER/CEA |.
| .|<----------------------------->|.
| ...................................
| | |
| | |
| | 4. NCR |
| |------------------------------>|
| | |
| | 5. DNCA session
| | established
| | |
| | 6. NCA |
| |<------------------------------|
| | |
| | |
| 7. Data traffic |
|----------------------------------------------------------->|
| | |
| | |
| | 8. NAT Bindings
| | created as per
| | directives in the
| | DNCA session
| | |
Figure 15: Initial NAT control request and session establishment
example
Detailed description of the steps shown in Figure 15:
1. The NAT-controller (co-located with the NAS here) creates state
for an end point based on a trigger. This could for example be
the successful establishment of a Point-to-Point Protocol (PPP)
[RFC1661] access session.
2. Based on the configuration of the DNCA Diameter peer within the
NAT-controller, the NAT-controller determines that NAT-control is
required and is to be enforced at a NAT-device.
3. If there is no Diameter session already established with the DNCA
Diameter peer within NAT-device, a Diameter connection is
established and Diameter Base CER/CEA are exchanged.
4. The NAT-Controller creates an NCR message (see below) and sends
it to the NAT-device. This example shows IPv4 to IPv4 address
and port translation. For IPv6 to IPv4 translation, the Framed-
IP-Address AVP would be replaced by the Framed-IPv6-Address AVP
with the value set to the IPv6 address of the end point.
< NC-Request > ::= < Diameter Header: TBD, REQ, PXY>
Session-Id = "natC.example.com:33041;23432;"
Auth-Application-Id = <DNCA Application ID>
Origin-Host = "natC.example.com"
Origin-Realm = "example.com"
Destination-Realm = "example.com"
Destination-Host = "nat-device.example.com"
NC-Request-Type = INITIAL_REQUEST
User-Name = "subscriber_example1"
Framed-IP-Address = "192.0.2.1"
NAT-Control-Install = {
NAT-Control-Definition = {
Protocol = TCP
Direction = OUT
NAT-Internal-Address = {
Framed-IP-Address = "192.0.2.1"
Port = 80
}
NAT-External-Address = {
Framed-IP-Address = "198.51.100.1"
Port = 80
}
}
Max-NAT-Bindings = 100
NAT-Control-Binding-Template = "local-policy"
}
5. The NAT-device establishes a DNCA session as it is able to comply
with the request.
6. The NAT-device sends an NCA to indicate the successful completion
of the request.
<NC-Answer> ::= < Diameter Header: TBD, PXY >
Session-Id = "natC.example.com:33041;23432;"
Origin-Host = "nat-device.example.com"
Origin-Realm = "example.com"
NC-Request-Type = INITIAL_REQUEST
Result-Code = DIAMETER_SUCCESS
7. The end point sends packets that reach the NAT-device.
8. The NAT-device performs NAT for traffic received from the end
point with source address 192.0.2.1. Traffic with source IP-
address 192.0.2.1 and port 80 are translated to the external IP-
address 198.51.100.1 and port 80. Traffic with source IP-address
192.0.2.1 and a source port different from 80 will be translated
to IP-address 198.51.100.1 and a port chosen by the NAT-device.
Note that this example assumes that the NAT-device follows
typical binding allocation rules for end points, in that only a
single external IP-address is used for all traffic received from
a single IP-address of an end point. The NAT-device will allow a
maximum of 100 NAT-bindings be created for the end point.
13.2. DNCA Session Update with Port Style Example
This section gives an example for a DNCA session update: A new set of
NAT-bindings is requested for an existing session. The request
contains a directive ( the "NAT-External-Port-Style" AVP set to
FOLLOW_INTERNAL_PORT_STYLE) that directs the NAT-device to maintain
port-sequence and port-oddity for the newly created NAT-bindings. In
the example shown, the internal ports are UDP port 1036 and 1037.
The NAT-device follows the directive selects the external ports
accordingly. The NAT-device would for example create a mapping of
192.0.2.1:1036 to 198.51.100.1:5056 and 192.0.2.1:1037 to
198.51.100.1:5057, thereby maintaining port oddity (1036->5056,
1037->5057) and sequence ( the consecutive internal ports 1036 and
1037 map to the consecutive external ports 5056 and 5057).
< NC-Request > ::= < Diameter Header: TBD, REQ, PXY>
Session-Id = "natC.example.com:33041;23432;"
Auth-Application-Id = <DNCA Application ID>
Origin-Host = "natC.example.com"
Origin-Realm = "example.com"
Destination-Realm = "example.com"
Destination-Host = "nat-device.example.com"
NC-Request-Type = UPDATE_REQUEST
NAT-Control-Install = {
NAT-Control-Definition = {
Protocol = UDP
Direction = OUT
NAT-Internal-Address = {
Framed-IP-Address = "192.0.2.1"
Port = 1035
}
}
NAT-Control-Definition = {
Protocol = UDP
Direction = OUT
NAT-Internal-Address = {
Framed-IP-Address = "192.0.2.1"
Port = 1036
}
}
NAT-External-Port-
Style = FOLLOW_INTERNAL_PORT_STYLE
}
13.3. DNCA Session Query Example
This section shows an example for DNCA session query for a subscriber
whose internal IP-Address is 192.0.2.1.
< NC-Request > ::= < Diameter Header: TBD, REQ, PXY>
Auth-Application-Id = <DNCA Application ID>
Origin-Host = "natC.example.com"
Origin-Realm = "example.com"
Destination-Realm = "example.com"
Destination-Host = "nat-device.example.com"
NC-Request-Type = QUERY_REQUEST
Framed-IP-Address = "192.0.2.1"
The NAT-device constructs an NCA to report all currently active NAT-
bindings whose internal address is 192.0.2.1.
<NC-Answer> ::= < Diameter Header: TBD, PXY >
Origin-Host = "nat-device.example.com"
Origin-Realm = "example.com"
NC-Request-Type = QUERY_REQUEST
NAT-Control-Definition = {
Protocol = TCP
Direction = OUT
NAT-Internal-Address = {
Framed-IP-Address = "192.0.2.1"
Port = 80
}
NAT-External-Address = {
Framed-IP-Address = "198.51.100.1"
Port = 80
}
Session-Id = "natC.example.com:33041;23432;"
}
NAT-Control-Definition = {
Protocol = TCP
Direction = OUT
NAT-Internal-Address = {
Framed-IP-Address = "192.0.2.1"
Port = 1036
}
NAT-External-Address = {
Framed-IP-Address = "198.51.100.1"
Port = 5056
}
Session-Id = "natC.example.com:33041;23432;"
}
NAT-Control-Definition = {
Protocol = TCP
Direction = OUT
NAT-Internal-Address = {
Framed-IP-Address = "192.0.2.1"
Port = 1037
}
NAT-External-Address = {
Framed-IP-Address = "198.51.100.1"
Port = 5057
}
Session-Id = "natC.example.com:33041;23432;"
}
13.4. DNCA Session Termination Example
In this example the NAT-controller decides to terminate the
previously established DNCA session. This could for example be the
case as a result of an access session (e.g. a PPP session) associated
with an end point been torn down.
NAT-Controller NAT-device
| |
| |
+--------------+ |
| 1. Trigger | |
+--------------+ |
| |
| |
| 2. STR |
|-------------------------------------->|
| |
| 3. DNCA session
| lookup
| 4. ACR |
|<--------------------------------------|
| |
| 5. ACA |
|-------------------------------------->|
| |
| |
| 6. DNCA bindings
| and session cleanup
| |
| 7. STA |
|<--------------------------------------|
| |
Figure 20: NAT control session termination example
The following steps describe the sequence of events for tearing down
the DNCA session in the example above:
1. The NAT-controller receives a trigger that a DNCA session
associated with a specific end point should be terminated. An
example event could be the termination of the PPP [RFC1661]
access session to an end point in a NAS. The NAS correspondingly
triggers the NAT-controller request tear-down of the associated
DNCA session.
2. The NAT-controller creates the required NCR message and sends it
to the NAT-device:
< STR > ::= < Diameter Header: 275, REQ, PXY>
Session-Id = "natC.example.com:33041;23432;"
Auth-Application-Id = <DNCA Application ID>
Origin-Host = "natC.example.com"
Origin-Realm = "example.com"
Destination-Realm = "example.com"
Destination-Host = "nat-device.example.com"
Termination-Cause = DIAMETER_LOGOUT
3. The NAT-device looks up the DNCA session based on the Session-Id
AVP and finds a previously established active session.
4. The NAT-device reports all NAT-bindings established for that
subscriber using an ACR:
< ACR > ::= < Diameter Header: 271, REQ, PXY>
Session-Id = "natC.example.com:33041;23432;"
Auth-Application-Id = <DNCA Application ID>
Origin-Host = "nat-device.example.com"
Origin-Realm = "example.com"
Destination-Realm = "example.com"
Destination-Host = "natC.example.com"
Accounting-Record-Type = STOP_RECORD
Accounting-Record-Number = 1
NAT-Control-Record = {
NAT-Control-Definition = {
Protocol = TCP
Direction = OUT
NAT-Internal-Address = {
Framed-IP-Address = "192.0.2.1"
Port = 5001
}
NAT-External-Address = {
Framed-IP-Address = "198.51.100.1"
Port = 7777
}
}
NAT-Control-Binding-Status = Removed
}
5. The NAT-controller receives and processes the ACR as per its
configuration. It responds with an ACA to the NAT-device.
<ACA> ::= < Diameter Header: 271, PXY >
Session-Id = "natC.example.com:33041;23432;"
Origin-Host = "natC.example.com"
Origin-Realm = "example.com"
Result-Code = DIAMETER_SUCCESS
Accounting-Record-Type = STOP_RECORD
Accounting-Record-Number = 1
6. On receipt of the ACA the NAT-device cleans up all NAT-bindings
and associated session state for the end point.
7. NAT-device sends an STA. On receipt of the STA the NAT-
controller will clean up the corresponding session state.
<STA> ::= < Diameter Header: TBD, PXY >
Session-Id = "natC.example.com:33041;23432;"
Origin-Host = "nat-device.example.com"
Origin-Realm = "example.com"
Result-Code = DIAMETER_SUCCESS
14. Acknowledgements
The authors would like to thank Jari Arkko, Wesley Eddy, Stephen
Farrell, Miguel A. Garcia, David Harrington, Jouni Korhonen, Matt
Lepinski, Avi Lior, Chris Metz, Pallavi Mishra, Lionel Morand, Robert
Sparks, Martin Stiemerling, Dave Thaler, Hannes Tschofenig, Sean
Turner, Shashank Vikram, Greg Weber, and Glen Zorn for their input on
this document.
15. Change History (to be removed prior to publication as an RFC)
Changes from -00 to -01 Changes from -00 to -01
a. new values for Result-Code AVP used - instead of Experimental- a. new values for Result-Code AVP used - instead of Experimental-
Result AVP Result AVP
b. added support for transport specific binding (UDP/TCP) b. added support for transport specific binding (UDP/TCP)
c. added support for twice-NAT c. added support for twice-NAT
skipping to change at page 43, line 46 skipping to change at page 56, line 28
a. expanded on the need for an SP controlling the maximum number of a. expanded on the need for an SP controlling the maximum number of
bindings of an end point (see introduction section) bindings of an end point (see introduction section)
b. added a paragraph in the security section outlining general mis- b. added a paragraph in the security section outlining general mis-
uses of NAT-control (non specific to DNCA), with DNCA being an uses of NAT-control (non specific to DNCA), with DNCA being an
example of such a NAT-control protocol example of such a NAT-control protocol
c. editorial changes c. editorial changes
15. Normative References Changes from -09 to -10
a. Section 4 and security considerations updated with RFC 2119
language
b. NAT-External-Port-Style AVP added to aid external port oddity
requirement as per MIDCOM framework
c. NAT related RFCs added in normative reference
d. Section 13 added to provide example DNCA message exchange flows
e. Added a description to provide DNCA comparison with MIDCOM
f. n:1 deployment model for NAT-controllers and NAT-devices
explicitly specified
g. editorial changes as per IESG DISCUSS comments
16. References
16.1. Normative References
[ETSIES283034] [ETSIES283034]
ETSI, "Telecommunications and Internet Converged Services ETSI, "Telecommunications and Internet Converged Services
and Protocols for Advanced Networks (TISPAN),Network and Protocols for Advanced Networks (TISPAN),Network
Attachment Sub-System (NASS),e4 interface based on the Attachment Sub-System (NASS),e4 interface based on the
Diameter protocol.", September 2008. Diameter protocol.", September 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
skipping to change at page 44, line 30 skipping to change at page 57, line 35
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5777] Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M., [RFC5777] Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M.,
and A. Lior, "Traffic Classification and Quality of and A. Lior, "Traffic Classification and Quality of
Service (QoS) Attributes for Diameter", RFC 5777, Service (QoS) Attributes for Diameter", RFC 5777,
February 2010. February 2010.
16.2. Informative References
[I-D.ietf-behave-lsn-requirements]
Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
and H. Ashida, "Common requirements for Carrier Grade NAT
(CGN)", draft-ietf-behave-lsn-requirements-03 (work in
progress), August 2011.
[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
RFC 1661, July 1994.
[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address
Translator (NAT) Terminology and Considerations",
RFC 2663, August 1999.
[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022,
January 2001.
[RFC3303] Srisuresh, P., Kuthan, J., Rosenberg, J., Molitor, A., and
A. Rayhan, "Middlebox communication architecture and
framework", RFC 3303, August 2002.
[RFC3304] Swale, R., Mart, P., Sijben, P., Brim, S., and M. Shore,
"Middlebox Communications (midcom) Protocol Requirements",
RFC 3304, August 2002.
[RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An
Architecture for Describing Simple Network Management
Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
December 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC4097] Barnes, M., "Middlebox Communications (MIDCOM) Protocol
Evaluation", RFC 4097, June 2005.
[RFC5189] Stiemerling, M., Quittek, J., and T. Taylor, "Middlebox
Communication (MIDCOM) Protocol Semantics", RFC 5189,
March 2008.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)",
RFC 6241, June 2011.
Authors' Addresses Authors' Addresses
Frank Brockners Frank Brockners
Cisco Cisco
Hansaallee 249, 3rd Floor Hansaallee 249, 3rd Floor
DUESSELDORF, NORDRHEIN-WESTFALEN 40549 DUESSELDORF, NORDRHEIN-WESTFALEN 40549
Germany Germany
Email: fbrockne@cisco.com Email: fbrockne@cisco.com
Shwetha Bhandari Shwetha Bhandari
Cisco Cisco
Cessna Business Park, Sarjapura Marathalli Outer Ring Road Cessna Business Park, Sarjapura Marathalli Outer Ring Road
Bangalore, KARNATAKA 560 087 Bangalore, KARNATAKA 560 087
India India
Email: shwethab@cisco.com Email: shwethab@cisco.com
Vaneeta Singh Vaneeta Singh
18, Cambridge Road 18, Cambridge Road
Bangalore 560008 Bangalore 560008
India India
Email: vaneeta.singh@gmail.com Email: vaneeta.singh@gmail.com
Victor Fajardo Victor Fajardo
Telcordia Technologies Telcordia Technologies
1 Telcordia Drive #1S-222 1 Telcordia Drive #1S-222
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