| Internet Engineering Task Force | F. Brockners |
| Internet-Draft | S. Bhandari |
| Intended status: Standards Track | Cisco |
| Expires: August 20, 2011 | V. Singh |
| V. Fajardo | |
| Telcordia Technologies | |
| February 16, 2011 |
Diameter Network Address and Port Translation Control Application
draft-ietf-dime-nat-control-07
This document describes the framework, messages, and procedures for the Diameter Network address and port translation Control Application. This Diameter application allows per endpoint control of Network Address Translators and Network Address and Port Translators, which are added to cope with IPv4-address space completion. This Diameter application allows external devices to configure and manage a Network Address Translator device - expanding the existing Diameter-based AAA and policy control capabilities with a Network Address Translators and Network Address and Port Translators control component. These external devices can be network elements in the data plane such as a Network Access Server, or can be more centralized control plane devices such as AAA-servers. This Diameter application establishes a context to commonly identify and manage endpoints on a gateway or server, and a Network Address Translator and Network Address and Port Translator device. This includes, for example, the control of the total number of Network Address Translator bindings allowed or the allocation of a specific Network Address Translator binding for a particular endpoint. In addition, it allows Network Address Translator devices to provide information relevant to accounting purposes.
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Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 20, 2011.
Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
Internet service providers have started to deploy Network Address Translators (NATs) and Network Address and Port Translators (NAPTs) at the edge of their networks to deal with the depletion of available public IPv4 addresses. This document defines a Diameter application for providers deploying such NAT and NAPT devices. The use of a Diameter application allows for simple integration into the existing Authentication, Authorization and Accounting (AAA) environment of a provider.
The Diameter Network address and port translation Control Application (DNCA) offers the following capabilities:
This document is structured as follows: Section 2 lists terminology, while Section 3 provides an introduction to DNCA and its overall deployment framework. Sections 4 to 8 cover DNCA specifics, with Section 4 describing session management, Section 5 the use of the Diameter base protocol, Section 6 new commands, Section 7 AVPs used, and Section 8 accounting aspects. Section 9 presents an AVP occurance table. IANA and security considerations are addressed in Sections 10 and 11.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
Abbreviations used in this document:
Figure 1 shows a typical network deployment for Internet access. A user’s IPv4 host gains access to the Internet though a NAS, which facilitates the authentication of the endpoint and configures the user’s connection according to the authorization and configuration data received from the AAA-server upon successful authentication. Public IPv4 addresses are used throughout the network.
+---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+---------+ +---------+ +----------+
| IPv4 | | | | IPv4 |
| Host |----------| NAS |-------------| Internet |
| | | | | |
+---------+ +---------+ +----------+
<-------------------- Public IPv4 ---------------------->
Figure 2 depicts the deployment scenario when a service provider introduces a NAT device to increase the efficiency of the global IPv4 address pool utilization. The objective is to provide the customer with connectivity to the public IPv4 Internet. The NAT device performs network address and port (and optionally address family) translation, depending on whether the access network uses private IPv4 addresses or public IPv6 addresses, to public IPv4 addresses. If the NAT device would be put in place without any endpoint awareness, the service offerings of the service provider could be hampered. Provisioning static NAT bindings for particular endpoints, using different public IP address pools for different set of endpoints; for example, residential or business customers, and reporting allocated bindings on a per endpoint basis is burdensome for a service provider if the NAT device is not aware of endpoints and allows per endpoint control and management, which easily integrates with the already existing per endpoint management infrastructure of the service provider.
+---------+
| |
| AAA |
| |
+---------+
|
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4/ | | | | | | IPv4 |
| IPv6 |----| NAS |----| NAT |----| Internet |
| Host | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Private IPv4 -----------><--- Public IPv4 --->
<-------- Public IPv6 -----------><--- Public IPv4 --->
DNCA runs between a DNCA Agent on the NAT and DNCA Manager. DNCA allows per endpoint control and management of NAT. Based on Diameter, DNCA integrates well with the suite of Diameter applications deployed for per endpoint authentication, authorization, accounting, and policy control in service provider networks.
DNCA offers:
DNCA allows controlling the behavior of a NAT device on a per endpoint basis during initial session establishment and at later stages by providing an update procedure for already established sessions. Using DNCA, per endpoint NAT binding information can be retrieved either using accounting mechanisms or through an explicit session query to the NAT.
The role of DNCA can be fulfilled by either the NAS or by an external server, such as AAA-server. The two deployment scenarios are outlined in Figure 3 (“integrated deployment”) and Figure 4 (“autonomous deployment”).
Within the figures (M) denotes the network element, which takes on DNCA Manager role. Similarly, (A) identifies the network element, which performs DNCA Agent role.
The integrated deployment approach hides the existence of the NAT device from external servers, such as the AAA-server as much as possible. It is suited for environments where minimal changes to the existing AAA deployment are desired. As DNCA Manager the NAS, initiates and manages session with the NAT device, exchanges NAT specific configuration information and handles reporting and accounting information. The NAS receives reporting and accounting information from NAT device. With this information, the NAS provides a single accounting record for the user. This reduces the usage of an external accounting system for correlating the information received from multiple sources.
An example network attachment for an integrated NAT deployment can be described as follows: An endpoint connects to the network, with the NAS being the point of attachment. After successful authentication, NAS receives endpoint related authorization data from the AAA-server. A portion of the authorization data applies to per endpoint configuration on the NAS itself, another portion describes authorization and configuration information for NAT control aimed at the NAT device. NAS will initiate a DNCA session to the NAT and send the relevant authorization and configuration information for the particular endpoint to the NAT device. This can comprise NAT bindings, which have to be pre-established for the endpoint, or management related configuration, such as the maximum number of NAT bindings allowed for the endpoint or accounting requirements. The NAT device sends its per endpoint accounting information to the NAS, which aggregates the accounting information received form the NAT device with its local accounting information for the endpoint into a single accounting stream towards the AAA-server.
+---------+
| |
| AAA |
| |
+---------+
|
|
|
+--------+ +---------+ +---------+ +----------+
| IPv4/ | | (M) | | (A) | | IPv4 |
| IPv6 |----| NAS |----| NAT |----| Internet |
| Host | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><--- Public IPv4 ---->
<-------- Private IPv4 ----------><--- Public IPv4 ---->
The autonomous deployment approach decouples user management on NAS and NAT device. The AAA system performing the role of DNCA Manager manages the connection to the NAT device, controls the per endpoint configuration, and also receives accounting and reporting information from the NAT device. Different from the integrated deployment scenario, the autonomous deployment scenario does not “hide” the existence of the NAT device from the AAA infrastructure. Here two accounting streams are received by the AAA-server for one particular endpoint, one from the NAS, and one from the NAT device.
+---------+
| (M) |
| AAA |---------
| | |
+---------+ |
| |
| |
| |
+--------+ +---------+ +---------+ +----------+
| IPv4/ | | | | (A) | | IPv4 |
| IPv6 |----| NAS |----| NAT |----| Internet |
| Host | | | | | | |
+--------+ +---------+ +---------+ +----------+
<-------- Public IPv6 ----------><---- Public IPv4 --->
<-------- Private IPv4 ----------><---- Public IPv4 --->
Note that this section forward references some of the commands and AVPs defined for DNCA. Please refer to Section 6 and Section 8 for details.
Authorization and control models supported by this application include the following parties:
The NAT control requesting entity is always DNCA Manager. DNCA Manager always initiates, updates, or terminates the sessions. This mode of operation is sometimes also referred to as "push mode".
DNCA Manager can be NAS or AAA-server. DNCA Manager initiates a session with DNCA Agent when it learns about the subscriber. DNCA Manager may learn about a subscriber when it receives authentication, authorization, or accounting request for that subscriber or by some other means, such as on the box configuration to identify a subscriber with respect to his IP packets.
DNCA Manager establishes a session with DNCA Agent to control the behavior of the NAT device. During session establishment, DNCA Manager passes along configuration information to DNCA Agent. The session configuration information comprises the maximum number of bindings allowed for the endpoint associated with this session, a set of pre-defined NAT bindings to be established for this endpoint, or a description of the address pool, external addresses to be allocated from.
DNCA Manager initiates the Diameter NAT Control session to DNCA Agent. DNCA Manager generates a NAT-Control Request (NCR) message to DNCA Agent with NC-Request-Type AVP set to INITIAL_REQUEST. On receipt of NCR DNCA Agent sets up a new session for the endpoint associated with the endpoint classifier(s) contained in the NCR. DNCA Agent notifies DNCA Manager about successful session setup using a NAT-Control Answer (NCA) message with Result-Code set to DIAMETER_SUCCESS. Figure 5 shows the initial protocol interaction between DNCA Manager and DNCA Agent.
The initial NAT-Control-Request may contain configuration information for the session, which specifies the behavior of the NAT device for the session. The configuration information, which may be included, comprises:
In certain cases, DNCA Agent may not be able to perform the tasks requested within the NCR. These include the following:
DNCA Manager DNCA Agent
| |
| |
| |
Trigger |
| |
| NCR |
|------------------------------------------>|
| (INITIAL_REQUEST, endpoint classifier, |
| session id, NAT control config data) |
| |
| |
| Create session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |
Session re-authorization is performed if DNCA Manager desires to change the behavior of the NAT for an existing session. Re-authorization could be used, for example, to change the number of allowed bindings for a particular session, or establish or remove a pre-defined binding.
DNCA Manager generates a NCR message to DNCA Agent with NC-Request-Type AVP set to UPDATE_REQUEST upon receiving a trigger signal. In case the session is updated successfully, DNCA Agent notifies DNCA Manager about successful session update using a NAT-Control Answer (NCA) message with Result-Code set to DIAMETER_SUCCESS. Figure 6 shows the protocol interaction between DNCA Manager and DNCA Agent.
In certain cases, DNCA Agent may not be able to perform the tasks requested within the NCR. These include the following:
Note: Already established bindings for the session will not be affected.
DNCA Manager DNCA Agent
| |
| |
| |
Change of session |
attributes |
| |
| NCR |
|------------------------------------------>|
| (UPDATE_REQUEST session id, |
| NAT control config data) |
| |
| |
| Update session state
| |
| |
| NCA |
|<------------------------------------------|
| (result code) |
| |
| |
Session query can be used by DNCA Manager to either retrieve information on the current bindings for a particular session at the NAT device or discover the session identifier for a particular external IP address/port pair.
DNCA Manager initiates a session query by sending a NCR message to DNCA Agent with NC-Request-Type AVP set to QUERY_REQUEST. Figure 7 shows the protocol interaction between DNCA Manager and DNCA Agent.
Two types of query requests exist. The first type of query request uses the session ID as input parameter to the query. It is to allow DNCA Manager retrieve the current set of bindings for a specific session. The second type of query request is used to retrieve the session identifiers, along with the associated bindings, matching a criteria. This enables DNCA Manager to find the sessions, which utilize a specific external IP address.
DNCA Manager DNCA Agent
| |
| |
| |
DNCA Session Established |
| |
| NCR |
|------------------------------------------>|
| (QUERY_REQUEST) |
| |
| |
| |
| Look up corresponding session
| and associated NAT Bindings
| |
| NCA |
|<------------------------------------------|
| (Result-Code) |
| |
| |
DNCA Manager generates a Session Terminate Request (STR) message to DNCA Agent upon receiving a trigger signal. The source of the trigger signal is outside the scope of this document. DNCA Agent sends accounting stop record reporting all the bindings and notifies DNCA Manager about successful session termination using a Session Terminate Answer (STA) message with Result-Code set to DIAMETER_SUCCESS. Figure 8 shows the protocol interaction between DNCA Manager and DNCA Agent.
If a DNCA Agent receives STR from a DNCA Manager and fails to find a matching session, DNCA Agent returns STA with Result-Code set to DIAMETER_UNKNOWN_SESSION_ID.
DNCA Manager DNCA Agent
| |
| |
Trigger |
| |
| STR |
|------------------------------------------->|
| (session id) |
| |
| |
| Remove NAT bindings
| of session
| |
| |
| Send accounting stop |
|<-------------------------------------------|
| for all session bindings |
| |
| Terminate Session /
| Remove session state
| |
| |
| |
| STA |
|<-------------------------------------------|
| (Result-Code) |
| |
This document does not cover details in case DNCA Manager and DNCA Agent are out of sync. This happens when DNCA Manager or DNCA Agent restart, (temporary) loss of network connectivity etc. DNCA Manager and DNCA Agent MUST have builtin redundancy support to recover state in case of failure.
Example failure cases include the following:
The Diameter Base Protocol defined by [RFC3588] applies with the clarifications listed in the present specification.
For secure transport of Diameter messages recommendations in [RFC3588] apply.
DNCA Agent MAY verify the identity of DNCA Manager during the Capabilities Exchange Request procedure.
DNCA Agent MAY verify if DNCA Manager that issues a NCR command is allowed and it is based on:
Accounting functionality (accounting session state machine, related command codes and AVPs) is defined in Section 9 below.
Each DNCA session MUST have a globally unique Session-ID as defined in [RFC3588], which MUST NOT be changed during the lifetime of a DNCA session. The Diameter Session-ID serves as the global endpoint identifier. DNCA Agent and DNCA Manager maintain state associated with the Session-ID. This globally unique Session-ID is used for updating, accounting, and terminating the session. DNCA session MUST NOT have more than one outstanding request at any given instant. DNCA Agent sends an Abort-Session-Request as defined in [RFC3588] if it is unable to maintain sessions due to resource limitation.
It is assumed that DNCA Manager knows the DiameterIdentity of DNCA Agent for a given endpoint. Both the Destination-Realm and Destination-Host AVPs are present in the request from DNCA Manager to DNCA Agent.
Diameter nodes conforming to this specification MUST advertise support for DNCA by including the value of TBD in the Auth-Application-Id of the Capabilities-Exchange-Request and Capabilities-Exchange-Answer command[RFC3588].
The following commands are used to establish, maintain and query NAT bindings.
The NAT-Control Request (NCR) command, indicated by the command field set to TBD and the "R" bit set in the Command Flags field, is sent from DNCA Manager to DNCA Agent in order to install NAT bindings.
User-Name, Logical-Access-Id, Physical-Access-ID, Framed-IP-Address, Framed-IPv6-Prefix , Framed-Interface-Id, EGRESS-VLANID, NAS-Port-ID, Address-Realm, Calling-Station-ID AVPs serve as identifiers for the subscriber.
Message Format:
< NC-Request > ::= < Diameter Header: TBD, REQ, PXY>
[ Session-Id ]
{ Auth-Application-Id }
{ Origin-Host }
{ Origin-Realm }
{ Destination-Realm }
{ Destination-Host }
{ NC-Request-Type }
[ Origin-State-Id ]
*1 [ NAT-Control-Remove ]
*1 [ NAT-Control-Install ]
[ User-Name ]
[ Logical-Access-Id ]
[ Physical-Access-ID ]
[ Framed-IP-Address ]
[ Framed-IPv6-Prefix ]
[ Framed-Interface-Id ]
[ EGRESS-VLANID]
[ NAS-Port-ID]
[ Address-Realm ]
[ Calling-Station-ID ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ AVP ]
The NAT-Control-Answer (NCA) command, indicated by the Command-Code field set to TBD and the "R" bit cleared in the Command Flags field, is sent by DNCA Agent in response to NAT-Control-Request command.
Message Format:
<NC-Answer> ::= < Diameter Header: TBD, PXY >
[ Session-Id ]
{ Origin-Host }
{ Origin-Realm }
{ NC-Request-Type }
[ Result-Code ]
* [ NAT-Control-Definition ]
[ Current-NAT-Bindings ]
[ Origin-State-Id ]
[ Error-Message ]
[ Error-Reporting-Host ]
* [ Failed-AVP ]
* [ Proxy-Info ]
[ Duplicate-Session-ID ]
* [ Redirect-Host]
[ Redirect-Host-Usage ]
[ Redirect-Max-Cache-Time ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ Failed-AVP ]
* [ AVP ]
* [ AVP ]
This section contains a set of finite state machines, representing the life cycle of DNCA session, which MUST be observed by all implementations of DNCA Diameter application. DNCA Agent and Manager are stateful and the state machine maintained is similar to the stateful Client and Server authorization state machine described in [RFC3588]. When a session is moved to the Idle state, any resources that were allocated for the particular session must be released. Any event not listed in the state machines MUST be considered as an error condition, and an answer, if applicable, MUST be returned to the originator of the message.
In the state table, the event 'Failure to send NCR' means that DNCA Manager is unable to send command NCR to the desired destination. This could be due to the peer being down, or due to the peer sending back a transient failure or temporary protocol error notification DIAMETER_TOO_BUSY or DIAMETER_LOOP_DETECTED in the Result-Code AVP of NCA.
In the state table "FAILED NCA" means that DNCA Agent was not able to honor corresponding NCR. This can happen due to any of the transient and permanent error at DNCA Agent indicated by the following error Result-Code values - RESOURCE_FAILURE, UNKNOWN_BINDING_RULE_NAME, BINDING_FAILURE, MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT, SESSION_EXISTS, INSUFFICIENT_CLASSIFIERS
The following state machine is observed by a DNCA Manager:
MANAGER
State Event Action New State
-------------------------------------------------------------
Idle New Host detected that Send Pending
requires NAT Control NCR
Initial
Request
Idle ASR Received Send ASA Idle
for unknown session with
Result-Code
= UNKNOWN_
SESSION_ID
Pending Successful NCA Setup Open
received complete
Pending Successful NCA Sent STR Discon
received
but Agent unable to provide
service
Pending Error processing successful Sent STR Discon
NCA
Pending Failed Cleanup Idle
NCA received
Open NAT control Send Open
update required NCR Update
Request
Open Successful Open
NCA received
Open Failed Cleanup Idle
NCA received.
Open Access Session end detected Send STR Discon
Open ASR Received, Send ASA Discon
client will comply with with
request to end the session Result-Code
= SUCCESS,
Send STR.
Open ASR Received, Send ASA Open
client will not comply with with
request to end the session Result-Code
!= SUCCESS
Discon ASR Received Send ASA Idle
Discon STA Received Discon. Idle
user/device
The following state machine is observed by a DNCA Agent:
AGENT
State Event Action New State
-------------------------------------------------------------
Idle NCR request Send Open
received, and successful
able to provide requested NCA
NAT control service
Idle NCR request Send Idle
received, and failed
unable to provide requested NCA
NAT control service
Open NCR request Send Open
received, and successful
able to provide requested NCA
NAT control service
Open NCR request Send Idle
received, and failed
unable to provide requested NCA,
NAT control service Cleanup
Open Unable to continue Send ASR Discon
providing requested
NAT control service
Discon Failure to send ASR Wait, Discon
resend ASR
Discon ASR successfully sent and Cleanup Idle
ASA Received with Result-Code
Not ASA Received None No Change.
Discon
Any STR Received Send STA, Idle
Cleanup.
AVPs reused from Diameter Base Protocol [RFC3588] are listed below.
+-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP | | | May |
| Attribute Name Code Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|Acct-Interim-Interval 85 Unsigned32 | M | P | Y |
|Auth-Application-Id 258 Unsigned32 | M | P | N |
|Destination-Host 293 DiamIdent | M | P | N |
|Destination-Realm 283 DiamIdent | M | P | N |
|Error-Message 281 UTF8String | M | P | N |
|Error-Reporting-Host 294 DiamIdent | M | P | N |
|Failed-AVP 279 Grouped | M | P | N |
|Origin-Host 264 DiamIdent | M | P | N |
|Origin-Realm 296 DiamIdent | M | P | N |
|Origin-State-Id 278 Unsigned32 | M | P | N |
|Proxy-Info 284 Grouped | M | P | N |
|Result-Code 268 Unsigned32 | M | P | N |
|Route-Record 282 DiamIdent | M | | N |
|Session-Id 263 UTF8String | M | P | Y |
|User-Name 1 UTF8String | M | P | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
+-------------------------------------------------------------------+
The Auth-Application-Id AVP (AVP Code 258) is assigned by IANA to Diameter applications. The value of the Auth-Application-Id for the Diameter NAT Control Application is TBD.
This section defines new values for the Result-Code AVP which SHALL be supported by all Diameter implementations that conform to the present document.
No new Result-Code AVP value is defined within this category.
Result-Code AVP values that fall within the transient failures category are those used to inform a peer that the request could not be satisfied at the time that it was received. The request may be able to be satisfied in the future.
The following new values of the Result-Code AVP are defined:
The Result-Code AVP values, which fall within the permanent failures category are used to inform the peer that the request failed, and should not be attempted again. The request may be able to be satisfied in the future.
The following new values of the Result-Code AVP are defined:
BINDING_FAILURE (TBD)
The following AVPs are reused from Diameter Network Access Server Application [RFC4005].
+---------------------+
| AVP Flag rules |
+------------------+------+------------|----+-----+----+-----|----+
| | AVP | | | |SHLD| MUST| |
| Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr|
|------------------|------|------------|----+-----+----+-----|----|
| NAS-Port | 5 | Unsigned32 | M | P | | V | Y |
| NAS-Port-Id | 87 | UTF8String | M | P | | V | Y |
| Calling-Station- | 31 | UTF8String | M | P | | V | Y |
| Id | | | | | | | |
| Framed-IP-Address| 8 | OctetString| M | P | | V | Y |
| Framed-Interface-| 96 | Unsigned64 | M | P | | V | Y |
| ID | | | | | | | |
| Framed-IPv6- | 97 | OctetString| M | P | | V | Y |
| Prefix | | | | | | | |
+------------------+------+------------|----+-----+----+-----|----+
The following AVPs are reused from "RADIUS Attributes for Virtual LAN and Priority Support" specification [RFC4675].
+---------------------+
| AVP Flag rules |
+------------------+------+------------|----+-----+----+-----|----+
| | AVP | | | |SHLD| MUST| |
| Attribute Name | Code | Value Type|MUST| MAY | NOT| NOT|Encr|
|------------------|------|------------|----+-----+----+-----|----|
| Egress-VLANID | 56 | OctetString| M | P | | V | Y |
+------------------+------+------------|----+-----+----+-----|----+
The following AVPs are reused from the Traffic Classification and Quality of Service (QoS) Attributes for Diameter [RFC5777].
+-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP | | | May |
| Attribute Name Code Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|Port TBD Integer32 | M | P | Y |
|IP-Address-Mask TBD Grouped | M | P | Y |
|Protocol TBD Enumerated | M | P | Y |
|Direction TBD Enumerated | M | P | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
+-------------------------------------------------------------------+
The following AVPs are reused from the Diameter e4 Application [ETSIES283034].
+-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP | | | May |
| Attribute Name Code Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|Address-Realm 301 OctetString | M,V | | Y |
|Logical-Access-Id 302 OctetString | V | M | Y |
|Physical-Access-ID 313 UTF8String | V | M | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
|V - Indicates whether the optional Vendor-ID field is present |
| in the AVP header. Vendor-Id header of all AVPs in |
| this table will be set to ETSI (13019). |
+-------------------------------------------------------------------+
The following table describes the new Diameter AVPs used in this document.
+-------------------+
| AVP Flag rules |
+-----------------------------------------------|-----+---+---------+
| AVP Section | | | May |
| Attribute Name Code Defined Data Type |MUST |MAY| encrypt |
+-----------------------------------------------+-----+---+---------+
|NC-Request-Type TBD 7.7.1 Enumerated | M | P | Y |
|NAT-Control-Install TBD 7.7.2 Grouped | M | P | Y |
|NAT-Control-Remove TBD 7.7.3 Grouped | M | P | Y |
|NAT-Control-Definition TBD 7.7.4 Grouped | M | P | Y |
|NAT-Internal-Address TBD 7.7.5 Grouped | M | P | Y |
|NAT-External-Address TBD 7.7.6 Grouped | M | P | Y |
|Max-NAT-Bindings TBD 7.7.7 Unsigned32 | M | P | Y |
|NAT-Control- TBD 7.7.8 OctetString| M | P | Y |
| Binding-Rule | | | |
|Duplicate- TBD 7.7.9 UTF8String | M | P | Y |
| Session-ID | | | |
|NAT-Control-Record TBD 8.2.1 Grouped | M | P | Y |
|NAT-Control- TBD 8.2.2 Enumerated | M | P | Y |
| Binding-Status | | | |
|Current-NAT-Bindings TBD 8.2.3 Unsigned32 | M | P | Y |
+-----------------------------------------------+-----+---+---------+
|M - Mandatory bit. An AVP with "M" bit set and its value MUST be |
| supported and recognized by a Diameter entity in order the |
| message, which carries this AVP, to be accepted. |
|P - Indicates the need for encryption for end-to-end security. |
|V - Vendor specific bit that indicates whether the optional |
| Vendor-ID field is present in the AVP header. |
+-------------------------------------------------------------------+
The NC-Request-Type AVP (AVP Code TBD) is of type Enumerated and contains the reason for sending the NAT-Control-Request command. It shall be present in all NAT-Control-Request messages.
The following values are defined:
UPDATE_REQUEST (2)
The NAT-Control AVP (AVP code TBD) is of type Grouped, and it is used to activate or install NAT bindings. It also contains Max-NAT-Bindings that defines maximum number of NAT bindings to be allowed for a subscriber and NAT-Control-Binding-Rule that references predefined policy template on DNCA Agent that may contain static bindings, maximum number of bindings to be allowed, address pool from which external binding address should be allocated.
AVP format:
NAT-Control-Install ::= < AVP Header: TBD >
* [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ]
[ Max-NAT-Bindings]
* [ AVP ]
The NAT-Control-Remove AVP (AVP code TBD) is of type Grouped, and it is used to deactivate or remove NAT bindings.
AVP format:
NAT-Control-Remove ::= < AVP Header: TBD >
* [ NAT-Control-Definition ]
[ NAT-Control-Binding-Rule ]
* [ AVP ]
The NAT-Control-Definition AVP (AVP code TBD) is of type Grouped, and it describes a binding.
The NAT-Control-Definition AVP uniquely identifies the binding between DNCA Agent and DNCA Manager.
If both the NAT-Internal-Address and NAT-External-Address AVP(s) are supplied, it is a pre-defined binding.
The Protocol AVP describes the transport protocol for the binding. The NAT-Control-Definition AVP can contain either zero or one Protocol AVP. If the Protocol AVP is omitted and if both internal and external address are specified then the binding reserves the addresses for all transport protocols.
The Direction AVP is of type Enumerated. It specifies the direction for the binding. The values of the enumeration applicable in this context are: "IN","OUT". If Direction AVP is OUT or absent, NAT-Internal-Address refers to the address of the subscriber device that needs to be translated. If Direction AVP is "IN", NAT-Internal-Address is the destination address that has to be translated.
AVP format:
NAT-Control-Definition ::= < AVP Header: TBD >
{ NAT-Internal-Address }
[ Protocol ]
[ Direction ]
[ NAT-External-Address ]
[ Session-Id ]
* [ AVP ]
The NAT-Internal-Address AVP (AVP code TBD) is of type Grouped. It describes the internal IP address and port for a binding. Framed-IPV6-Prefix and Framed-IP-Address AVPs are mutually exclusive.
AVP format:
NAT-Internal-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ]
[ Framed-IPv6-Prefix ]
[ Port]
* [ AVP ]
The NAT-External-Address AVP (AVP code TBD) is of type Grouped, and it describes the external IP address and port for a binding. IP-Address-Mask AVP can only be specified when Framed-IP-Address AVP is present. External IP address specified in this attribute can be reused for multiple subscribers by specifying the same address in the respective NAT-External-Address AVPs.
AVP format:
NAT-External-Address ::= < AVP Header: TBD >
[ Framed-IP-Address ]
[ IP-Address-Mask ]
[ Port ]
* [ AVP ]
The Max-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32. It indicates the maximum number of NAT bindings allowed.
The NAT-Control-Binding-Rule AVP (AVP code TBD) is of type OctetString. It defines a name for a policy template that will be predefined at NAT. Details on the contents and structure of the template and configuration are outside the scope of this document. The policy to which this AVP refers to may contain NAT bindings, address pool for external address allocation of NAT binding, and maximum allowed NAT bindings. Such policy template can be reused by specifying same NAT-Control-Binding-Rule AVP in corresponding NAT-Control-Install AVPs of multiple subscribers.
The Duplicate-Session-Id AVP (AVP Code TBD) is of type UTF8String. It is used to report error and contains the Session-Id of an existing session.
DNCA reuses session based accounting as defined in Diameter Base Protocol[RFC3588] to report the bindings per endpoint. This reporting is achieved by sending Diameter Accounting Requests (ACR) [Start, Interim and Stop] from DNCA Agent to DNCA Manager.
DNCA Agent sends an ACR Start on receiving an NCR with NC-Request-Type AVP set to INITIAL_REQUEST for a session or on creation of the first binding for a session requested in an earlier NCR. DNCA may send ACR Interim updates, if required, either due to a change in bindings resulting from a NCR with NC-Request-Type AVP set to UPDATE_REQUEST, or periodically as specified in Acct-Interim-Interval by DNCA Manager, or when it creates or tears down bindings. An ACR Stop is sent by DNCA Agent on receiving STR.
The function of correlating the multiple bindings used by an endpoint at any given time is relegated to the post processor.
DNCA Agent may trigger an interim accounting record when maximum number of bindings, if received in NCR, is reached.
The ACR and ACA messages are reused as defined in Diameter Base Protocol [RFC3588] for exchanging endpoint NAT binding details between DNCA Agent and DNCA Manager. DNCA Application ID is used in the accounting commands. ACR contains one or more optional NAT-Control-Record AVP to report the bindings. DNCA Agent indicates the number of allocated NAT bindings to DNCA Manager using the Current-NAT-Bindings AVP. This number needs to match the number of bindings identified as active within the NAT-Control-Record AVP.
In addition to AVPs for ACR specified in [RFC3588], DNCA Agent must add the NAT-Control-Record AVP.
The NAT-Control-Record AVP (AVP code TBD) is of type Grouped. It describes a binding and its status. If NAT-Control-Binding-Status is set to Created, Event-Timestamp indicates the binding creation time. If NAT-Control-Binding-Status is set to Removed, Event-Timestamp indicates the binding removal time. If NAT-Control-Binding-Status is active, Event-Timestamp need not be present; if a value is present, it indicates that binding is active at the given time.
NAT-Control-Record ::= < AVP Header: TBD >
{ NAT-Control-Definition }
{ NAT-Control-Binding-Status }
[ Event-Timestamp ]
The NAT-Control-Binding-Status AVP (AVP code TBD) is of type enumerated. It indicates the status of the binding - created, removed, or active.
The following values are defined:
The Current-NAT-Bindings AVP (AVP code TBD) is of type Unsigned32. It indicates number of NAT bindings active on NAT device.
The following sections presents the AVPs defined in this document and specifies the Diameter messages in which, they MAY be present. Note: AVPs that can only be present within a Grouped AVP are not represented in this table.
The table uses the following symbols:
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 UPDATE_REQUEST.
+-------------------+
| Command Code |
+-----------------------------------+-------------------+
| Attribute Name NCR NCA |
+-------------------------------------------------------+
|NC-Request-Type 1 1 |
|NAT-Control-Install 0-1 0 |
|NAT-Control-Remove 0-1 0 |
|NAT-Control-Definition 0 0 |
|Current-NAT-Bindings 0 0 |
|Duplicate-Session-Id 0 0-1 |
+-------------------------------------------------------+
The following table lists DNCA specific AVPs that have to be present in NCR and NCA with NC-Request-Type set to QUERY_REQUEST.
+-------------------+
| Command Code |
+-----------------------------------+-------------------+
| Attribute Name NCR NCA |
+-------------------------------------------------------+
|NC-Request-Type 1 1 |
|NAT-Control-Install 0 0 |
|NAT-Control-Remove 0 0 |
|NAT-Control-Definition 0 0+ |
|Current-NAT-Bindings 0 1 |
|Duplicate-Session-Id 0 0 |
+-------------------------------------------------------+
The following table lists DNCA specific AVPs, which may or may not be present in ACR and ACA messages.
+-------------------+
| Command Code |
+-----------------------------------+-------------------+
| Attribute Name ACR ACA |
+-------------------------------------------------------+
|NAT-Control-Record 0+ 0 |
|Current-NAT-Bindings 1 0 |
+-------------------------------------------------------+
This section contains the namespaces that have either been created in this specification or had their values assigned to existing namespaces managed by IANA.
IANA is requested to allocate command code values for the following.
Registry:
| Code Value | Name | Reference |
|---|---|---|
| to be assigned | NAT-Control-Request (NCR), NAT-Control-Answer (NCA) | Section 6.1, Section 6.2 |
IANA is requested to allocate AVP codes for the following AVPs that are defined in this document.
Registry:
| Code Value | Name | Reference |
|---|---|---|
| to be assigned | NC-Request-Type | Section 8.7.1 |
| to be assigned | NAT-Control-Install | Section 8.7.2 |
| to be assigned | NAT-Control-Remove | Section 8.7.3 |
| to be assigned | NAT-Control-Definition | Section 8.7.4 |
| to be assigned | NAT-Internal-Address | Section 8.7.5 |
| to be assigned | NAT-External-Address | Section 8.7.6 |
| to be assigned | Max-NAT-Bindings | Section 8.7.7 |
| to be assigned | NAT-Control-Binding-Rule | Section 8.7.8 |
| to be assigned | Duplicate-Session-Id | Section 8.7.9 |
| to be assigned | NAT-Control-Record | Section 9.2.1 |
| to be assigned | NAT-Control-Binding-Status | Section 9.2.2 |
| to be assigned | Current-NAT-Bindings | Section 9.2.3 |
Section 8.2 defines several new values for the Result-Code AVP for transient and permanent failures. IANA is requested to allocate the corresponding values from the ranges for transient (4xxx) and permantent (5xxx) failures.
| Code Value | Name | Reference |
|---|---|---|
| to be assigned (4xxx) | RESOURCE_FAILURE | Section 8.2.2 |
| to be assigned (5xxx) | UNKNOWN_BINDING_RULE_NAME | Section 8.2.3 |
| to be assigned (5xxx) | BINDING_FAILURE | Section 8.2.3 |
| to be assigned (5xxx) | MAXIMUM_BINDINGS_REACHED_FOR_ENDPOINT | Section 8.2.3 |
| to be assigned (5xxx) | SESSION_EXISTS | Section 8.2.3 |
| to be assigned (5xxx) | INSUFFICIENT_CLASSIFIERS | Section 8.2.3 |
IANA is requested to allocate the following application ID using the next value from the 7-16777215 range.
Registry:
| ID Value | Name | Reference |
|---|---|---|
| to be assigned | Diameter NAT Control Application | Section 4 |
Similar to the impact of Diameter QoS application (see [RFC5866]) on authorization of QoS reservations, this document describes procedures for authorizing NAT related attributes and parameters by an entity, which is non-local to the device performing NAT. The security considerations for the Diameter QoS application (see [RFC5866] section 11) apply in a similar way to DNCA. To secure the information exchange between the authorizing entity (DNCA Manager) and the NAT device (DNCA Agent) requires bilateral authentication of the involved parties, authorization of the involved parties to perform the required procedures and functions, and procedures to ensure integrity and confidentiality of the information exchange MAY be performed. DNCA makes use of the capabilities offered by Diameter and the underlying transport protocols to deliver these requirements (see Section 5.1 ).
It is assumed that DNCA Agent and DNCA Manager are in the same domain and have a mutual trust set up. Authorization between DNCA Agent and DNCA Manager is beyond the scope of this document.
The authors would like to thank Jouni Korhonen, Avi Lior, Chris Metz, Pallavi Mishra, Lionel Morand, Hannes Tschofenig, Shashank Vikram, Greg Weber, and Glen Zorn for their input on this document.
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| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. |
| [RFC3588] | Calhoun, P., Loughney, J., Guttman, E., Zorn, G. and J. Arkko, "Diameter Base Protocol", RFC 3588, September 2003. |
| [RFC4675] | Congdon, P., Sanchez, M. and B. Aboba, "RADIUS Attributes for Virtual LAN and Priority Support", RFC 4675, September 2006. |
| [RFC5777] | Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M. and A. Lior, "Traffic Classification and Quality of Service (QoS) Attributes for Diameter", RFC 5777, February 2010. |
| [ETSIES283034] | ETSI, , "Telecommunications and Internet Converged Services and Protocols for Advanced Networks (TISPAN),Network Attachment Sub-System (NASS),e4 interface based on the Diameter protocol.", September 2008. |
| [RFC4005] | Calhoun, P., Zorn, G., Spence, D. and D. Mitton, "Diameter Network Access Server Application", RFC 4005, August 2005. |
| [RFC5866] | Sun, D., McCann, P., Tschofenig, H., Tsou, T., Doria, A. and G. Zorn, "Diameter Quality-of-Service Application", RFC 5866, May 2010. |