path: root/lib/diameter/doc/standard/rfc4005.txt

Network Working Group                                         P. Calhoun
Request for Comments: 4005                                       G. Zorn
Category: Standards Track                             Cisco Systems Inc.
                                                               D. Spence
                                                              Consultant
                                                               D. Mitton
                                                       Circular Networks
                                                             August 2005


               Diameter Network Access Server Application

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document describes the Diameter protocol application used for
   Authentication, Authorization, and Accounting (AAA) services in the
   Network Access Server (NAS) environment.  When combined with the
   Diameter Base protocol, Transport Profile, and Extensible
   Authentication Protocol specifications, this application
   specification satisfies typical network access services requirements.

   Initial deployments of the Diameter protocol are expected to include
   legacy systems.  Therefore, this application has been carefully
   designed to ease the burden of protocol conversion between RADIUS and
   Diameter.  This is achieved by including the RADIUS attribute space
   to eliminate the need to perform many attribute translations.

   The interactions between Diameter applications and RADIUS specified
   in this document are to be applied to all Diameter applications.  In
   this sense, this document extends the Base Diameter protocol.









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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
       1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . .  5
       1.2.  Requirements Language  . . . . . . . . . . . . . . . . .  6
       1.3.  Advertising Application Support  . . . . . . . . . . . .  6
   2.  NAS Calls, Ports, and Sessions . . . . . . . . . . . . . . . .  6
       2.1.  Diameter Session Establishment . . . . . . . . . . . . .  7
       2.2.  Diameter Session Reauthentication or Reauthorization . .  7
       2.3.  Diameter Session Termination . . . . . . . . . . . . . .  8
   3.  NAS Messages . . . . . . . . . . . . . . . . . . . . . . . . .  9
       3.1.  AA-Request (AAR) Command . . . . . . . . . . . . . . . .  9
       3.2.  AA-Answer (AAA) Command  . . . . . . . . . . . . . . . . 11
       3.3.  Re-Auth-Request (RAR) Command  . . . . . . . . . . . . . 13
       3.4.  Re-Auth-Answer (RAA) Command . . . . . . . . . . . . . . 14
       3.5.  Session-Termination-Request (STR) Command  . . . . . . . 15
       3.6.  Session-Termination-Answer (STA) Command . . . . . . . . 15
       3.7.  Abort-Session-Request (ASR) Command  . . . . . . . . . . 16
       3.8.  Abort-Session-Answer (ASA) Command . . . . . . . . . . . 17
       3.9.  Accounting-Request (ACR) Command . . . . . . . . . . . . 17
       3.10. Accounting-Answer (ACA) Command. . . . . . . . . . . . . 19
   4.  NAS Session AVPs . . . . . . . . . . . . . . . . . . . . . . . 20
       4.1.  Call and Session Information . . . . . . . . . . . . . . 21
       4.2.  NAS-Port AVP . . . . . . . . . . . . . . . . . . . . . . 22
       4.3.  NAS-Port-Id AVP  . . . . . . . . . . . . . . . . . . . . 22
       4.4.  NAS-Port-Type AVP  . . . . . . . . . . . . . . . . . . . 22
       4.5.  Called-Station-Id AVP  . . . . . . . . . . . . . . . . . 23
       4.6.  Calling-Station-Id AVP . . . . . . . . . . . . . . . . . 23
       4.7.  Connect-Info AVP . . . . . . . . . . . . . . . . . . . . 24
       4.8.  Originating-Line-Info AVP  . . . . . . . . . . . . . . . 24
       4.9.  Reply-Message AVP  . . . . . . . . . . . . . . . . . . . 25
   5.  NAS Authentication AVPs  . . . . . . . . . . . . . . . . . . . 26
       5.1.  User-Password AVP  . . . . . . . . . . . . . . . . . . . 26
       5.2.  Password-Retry AVP . . . . . . . . . . . . . . . . . . . 27
       5.3.  Prompt AVP . . . . . . . . . . . . . . . . . . . . . . . 27
       5.4.  CHAP-Auth AVP  . . . . . . . . . . . . . . . . . . . . . 27
       5.5.  CHAP-Algorithm AVP . . . . . . . . . . . . . . . . . . . 28
       5.6.  CHAP-Ident AVP . . . . . . . . . . . . . . . . . . . . . 28
       5.7.  CHAP-Response AVP  . . . . . . . . . . . . . . . . . . . 28
       5.8.  CHAP-Challenge AVP . . . . . . . . . . . . . . . . . . . 28
       5.9.  ARAP-Password AVP  . . . . . . . . . . . . . . . . . . . 28
       5.10. ARAP-Challenge-Response AVP. . . . . . . . . . . . . . . 28
       5.11. ARAP-Security AVP. . . . . . . . . . . . . . . . . . . . 29
       5.12. ARAP-Security-Data AVP . . . . . . . . . . . . . . . . . 29
   6.  NAS Authorization AVPs . . . . . . . . . . . . . . . . . . . . 29
       6.1.  Service-Type AVP . . . . . . . . . . . . . . . . . . . . 30
       6.2.  Callback-Number AVP  . . . . . . . . . . . . . . . . . . 32
       6.3.  Callback-Id AVP  . . . . . . . . . . . . . . . . . . . . 32



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       6.4.  Idle-Timeout AVP . . . . . . . . . . . . . . . . . . . . 32
       6.5.  Port-Limit AVP . . . . . . . . . . . . . . . . . . . . . 32
       6.6.  NAS-Filter-Rule AVP  . . . . . . . . . . . . . . . . . . 32
       6.7.  Filter-Id AVP  . . . . . . . . . . . . . . . . . . . . . 33
       6.8.  Configuration-Token AVP  . . . . . . . . . . . . . . . . 33
       6.9.  QoS-Filter-Rule AVP  . . . . . . . . . . . . . . . . . . 33
       6.10. Framed Access Authorization AVPs . . . . . . . . . . . . 35
             6.10.1.  Framed-Protocol AVP . . . . . . . . . . . . . . 35
             6.10.2.  Framed-Routing AVP. . . . . . . . . . . . . . . 35
             6.10.3.  Framed-MTU AVP. . . . . . . . . . . . . . . . . 35
             6.10.4.  Framed-Compression AVP. . . . . . . . . . . . . 36
       6.11. IP Access Authorization AVPs.. . . . . . . . . . . . . . 36
             6.11.1.  Framed-IP-Address AVP . . . . . . . . . . . . . 36
             6.11.2.  Framed-IP-Netmask AVP . . . . . . . . . . . . . 36
             6.11.3.  Framed-Route AVP. . . . . . . . . . . . . . . . 37
             6.11.4.  Framed-Pool AVP . . . . . . . . . . . . . . . . 37
             6.11.5.  Framed-Interface-Id AVP . . . . . . . . . . . . 37
             6.11.6.  Framed-IPv6-Prefix AVP. . . . . . . . . . . . . 38
             6.11.7.  Framed-IPv6-Route AVP . . . . . . . . . . . . . 38
             6.11.8.  Framed-IPv6-Pool AVP. . . . . . . . . . . . . . 38
       6.12. IPX Access . . . . . . . . . . . . . . . . . . . . . . . 38
             6.12.1.  Framed-IPX-Network AVP. . . . . . . . . . . . . 39
       6.13. AppleTalk Network Access . . . . . . . . . . . . . . . . 39
             6.13.1.  Framed-AppleTalk-Link AVP . . . . . . . . . . . 39
             6.13.2.  Framed-AppleTalk-Network AVP . . . . . . . . .  39
             6.13.3.  Framed-AppleTalk-Zone AVP . . . . . . . . . . . 40
       6.14. AppleTalk Remote Access. . . . . . . . . . . . . . . . . 40
             6.14.1.  ARAP-Features AVP . . . . . . . . . . . . . . . 40
             6.14.2.  ARAP-Zone-Access AVP. . . . . . . . . . . . . . 40
       6.15. Non-Framed Access Authorization AVPs . . . . . . . . . . 40
             6.15.1.  Login-IP-Host AVP . . . . . . . . . . . . . . . 40
             6.15.2.  Login-IPv6-Host AVP . . . . . . . . . . . . . . 41
             6.15.3.  Login-Service AVP . . . . . . . . . . . . . . . 41
       6.16. TCP Services . . . . . . . . . . . . . . . . . . . . . . 42
             6.16.1.  Login-TCP-Port AVP . . . . . . . . . . . . . .  42
       6.17. LAT Services . . . . . . . . . . . . . . . . . . . . . . 42
             6.17.1.  Login-LAT-Service AVP . . . . . . . . . . . . . 42
             6.17.2.  Login-LAT-Node AVP. . . . . . . . . . . . . . . 43
             6.17.3.  Login-LAT-Group AVP . . . . . . . . . . . . . . 43
             6.17.4.  Login-LAT-Port AVP. . . . . . . . . . . . . . . 43
   7.  NAS Tunneling  . . . . . . . . . . . . . . . . . . . . . . . . 44
       7.1.  Tunneling AVP  . . . . . . . . . . . . . . . . . . . . . 44
       7.2.  Tunnel-Type AVP  . . . . . . . . . . . . . . . . . . . . 45
       7.3.  Tunnel-Medium-Type AVP . . . . . . . . . . . . . . . . . 46
       7.4.  Tunnel-Client-Endpoint AVP . . . . . . . . . . . . . . . 46
       7.5.  Tunnel-Server-Endpoint AVP . . . . . . . . . . . . . . . 47
       7.6.  Tunnel-Password AVP  . . . . . . . . . . . . . . . . . . 48
       7.7.  Tunnel-Private-Group-Id AVP  . . . . . . . . . . . . . . 48



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       7.8.  Tunnel-Assignment-Id AVP . . . . . . . . . . . . . . . . 48
       7.9.  Tunnel-Preference AVP  . . . . . . . . . . . . . . . . . 49
       7.10. Tunnel-Client-Auth-Id AVP. . . . . . . . . . . . . . . . 50
       7.11. Tunnel-Server-Auth-Id AVP. . . . . . . . . . . . . . . . 50
   8.  NAS Accounting . . . . . . . . . . . . . . . . . . . . . . . . 50
       8.1.  Accounting-Input-Octets AVP  . . . . . . . . . . . . . . 51
       8.2.  Accounting-Output-Octets AVP . . . . . . . . . . . . . . 52
       8.3.  Accounting-Input-Packets AVP . . . . . . . . . . . . . . 52
       8.4.  Accounting-Output-Packets AVP  . . . . . . . . . . . . . 52
       8.5.  Acct-Session-Time AVP  . . . . . . . . . . . . . . . . . 52
       8.6.  Acct-Authentic AVP . . . . . . . . . . . . . . . . . . . 52
       8.7.  Accounting-Auth-Method AVP . . . . . . . . . . . . . . . 53
       8.8.  Acct-Delay-Time  . . . . . . . . . . . . . . . . . . . . 53
       8.9.  Acct-Link-Count  . . . . . . . . . . . . . . . . . . . . 54
       8.10. Acct-Tunnel-Connection AVP . . . . . . . . . . . . . . . 54
       8.11. Acct-Tunnel-Packets-Lost AVP . . . . . . . . . . . . . . 55
   9.  RADIUS/Diameter Protocol Interactions  . . . . . . . . . . . . 55
       9.1.  RADIUS Request Forwarded as Diameter Request . . . . . . 55
             9.1.1.   RADIUS Dynamic Authorization Considerations . . 59
       9.2.  Diameter Request Forwarded as RADIUS Request . . . . . . 60
             9.2.1.   RADIUS Dynamic Authorization Considerations . . 62
       9.3.  AVPs Used Only for Compatibility . . . . . . . . . . . . 63
             9.3.1.   NAS-Identifier AVP. . . . . . . . . . . . . . . 63
             9.3.2.   NAS-IP-Address AVP. . . . . . . . . . . . . . . 64
             9.3.3.   NAS-IPv6-Address AVP. . . . . . . . . . . . . . 65
             9.3.4.   State AVP . . . . . . . . . . . . . . . . . . . 65
             9.3.5.   Termination-Cause AVP Code Values . . . . . . . 66
             9.3.6.   Origin-AAA-Protocol . . . . . . . . . . . . . . 68
       9.4.  Prohibited RADIUS Attributes . . . . . . . . . . . . . . 69
       9.5.  Translatable Diameter AVPs . . . . . . . . . . . . . . . 69
       9.6.  RADIUS Vendor-Specific Attributes  . . . . . . . . . . . 69
             9.6.1.  Forwarding a Diameter Vendor Specific AVP as a
                     RADIUS VSA . . . . . . . . . . . . . . . . . . . 70
             9.6.2.  Forwarding a RADIUS VSA as a Diameter Vendor
                     Specific AVP . . . . . . . . . . . . . . . . . . 70
   10. AVP Occurrence Tables. . . . . . . . . . . . . . . . . . . . . 71
       10.1. AA-Request/Answer AVP Table. . . . . . . . . . . . . . . 71
       10.2. Accounting AVP Tables. . . . . . . . . . . . . . . . . . 73
             10.2.1.  Accounting Framed Access AVP Table. . . . . . . 74
             10.2.2.  Accounting Non-Framed Access AVP Table. . . . . 76
   11. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 77
       11.1. Command Codes. . . . . . . . . . . . . . . . . . . . . . 77
       11.2. AVP Codes. . . . . . . . . . . . . . . . . . . . . . . . 78
       11.3. Application Identifier . . . . . . . . . . . . . . . . . 78
       11.4. CHAP-Algorithm AVP Values. . . . . . . . . . . . . . . . 78
       11.5. Accounting-Auth-Method AVP Values. . . . . . . . . . . . 78
       11.6. Origin-AAA-Protocol AVP Values . . . . . . . . . . . . . 78
   12. Security Considerations. . . . . . . . . . . . . . . . . . . . 78



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   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 79
       13.1. Normative References . . . . . . . . . . . . . . . . . . 79
       13.2. Informative References . . . . . . . . . . . . . . . . . 80
   14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 83
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 84
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 85

1.  Introduction

   This document describes the Diameter protocol application used for
   AAA in the Network Access Server (NAS) environment.  When combined
   with the Diameter Base protocol [BASE], Transport Profile
   [DiamTrans], and EAP [DiamEAP] specifications, this Diameter NAS
   application specification satisfies NAS-related requirements defined
   in RFC 2989 [AAACriteria] and RFC 3169 [NASCriteria].

   Initial deployments of the Diameter protocol are expected to include
   legacy systems.  Therefore, this application has been carefully
   designed to ease the burden of protocol conversion between RADIUS and
   Diameter.  This is achieved by including the RADIUS attribute space
   to eliminate the need to perform many attribute translations.

   The interactions specified in this document between Diameter
   applications and RADIUS are to be applied to all Diameter
   applications.  In this sense, this document extends the Base Diameter
   protocol [BASE].

   First, this document describes the operation of a Diameter NAS
   application.  Then it defines the Diameter message Command-Codes.
   The following sections list the AVPs used in these messages, grouped
   by common usage.  These are session identification, authentication,
   authorization, tunneling, and accounting.  The authorization AVPs are
   further broken down by service type.  Interaction and backward
   compatibility issues with RADIUS are discussed in later sections.

1.1.  Terminology

   The base Diameter [BASE] specification section 1.4 defines most of
   the terminology used in this document.  Additionally, the following
   terms and acronyms are used in this application:

   NAS (Network Access Server) - A device that provides an access
   service for a user to a network.  The service may be a network
   connection or a value-added service such as terminal emulation
   [NASModel].






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   PPP (Point-to-Point Protocol) - A multiprotocol serial datalink.  PPP
   is the primary IP datalink used for dial-in NAS connection service
   [PPP].

   CHAP (Challenge Handshake Authentication Protocol) - An
   authentication process used in PPP [PPPCHAP].

   PAP (Password Authentication Protocol) - A deprecated PPP
   authentication process, but often used for backward compatibility
   [PAP].

   SLIP (Serial Line Interface Protocol) - A serial datalink that only
   supports IP.  A design prior to PPP.

   ARAP (Appletalk Remote Access Protocol) - A serial datalink for
   accessing Appletalk networks [ARAP].

   IPX (Internet Packet Exchange) - The network protocol used by NetWare
   networks [IPX].

   LAT (Local Area Transport) - A Digital Equipment Corp. LAN protocol
   for terminal services [LAT].

   VPN (Virtual Private Network) - In this document, this term is used
   to describe access services that use tunneling methods.

1.2.  Requirements Language

   In this document, the key words "MAY", "MUST", "MUST NOT",
   "OPTIONAL", "RECOMMENDED", "SHOULD", and "SHOULD NOT" are to be
   interpreted as described in [Keywords].

1.3.  Advertising Application Support

   Diameter applications conforming to this specification MUST advertise
   support by including the value of one (1) in the Auth-Application-Id
   of Capabilities-Exchange-Request (CER), AA-Request (AAR), and AA-
   Answer (AAA) messages.  All other messages are defined by [BASE] and
   use the Base application id value.

2.  NAS Calls, Ports, and Sessions

   The arrival of a new call or service connection at a port of a
   Network Access Server (NAS) starts a Diameter NAS message exchange.
   Information about the call, the identity of the user, and the user's
   authentication information are packaged into a Diameter AA-Request
   (AAR) message and sent to a server.




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   The server processes the information and responds with a Diameter
   AA-Answer (AAA) message that contains authorization information for
   the NAS, or a failure code (Result-Code AVP).  A value of
   DIAMETER_MULTI_ROUND_AUTH indicates an additional authentication
   exchange, and several AAR and AAA messages may be exchanged until the
   transaction completes.

   Depending on the Auth-Request-Type AVP, the Diameter protocol allows
   authorization-only requests that contain no authentication
   information from the client.  This capability goes beyond the Call
   Check capabilities described in section 5.6 of [RADIUS] in that no
   access decision is requested.  As a result, service cannot be started
   as a result of a response to an authorization-only request without
   introducing a significant security vulnerability.

   Since no equivalent capability exists in RADIUS, authorization-only
   requests from a NAS implementing Diameter may not be easily
   translated to an equivalent RADIUS message by a Diameter/RADIUS
   gateway.  For example, when a Diameter authorization-only request
   cannot be translated to a RADIUS Call Check, it would be necessary
   for the Diameter/RADIUS gateway to add authentication information to
   the RADIUS Access Request.  On receiving the Access-Reply, the
   Diameter/RADIUS gateway would need to discard the access decision
   (Accept/Reject).  It is not clear whether these translations can be
   accomplished without adding significant security vulnerabilities.

2.1.  Diameter Session Establishment

   When the authentication or authorization exchange completes
   successfully, the NAS application SHOULD start a session context.  If
   the Result-Code of DIAMETER_MULTI_ROUND_AUTH is returned, the
   exchange continues until a success or error is returned.

   If accounting is active, the application MUST also send an Accounting
   message [BASE].  An Accounting-Record-Type of START_RECORD is sent
   for a new session.  If a session fails to start, the EVENT_RECORD
   message is sent with the reason for the failure described.

   Note that the return of an unsupportable Accounting-Realtime-Required
   value [BASE] would result in a failure to establish the session.

2.2.  Diameter Session Reauthentication or Reauthorization

   The Diameter Base protocol allows users to be periodically
   reauthenticated and/or reauthorized.  In such instances, the
   Session-Id AVP in the AAR message MUST be the same as the one present
   in the original authentication/authorization message.




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   A Diameter server informs the NAS of the maximum time allowed before
   reauthentication or reauthorization via the Authorization-Lifetime
   AVP [BASE].  A NAS MAY reauthenticate and/or reauthorize before the
   end, but A NAS MUST reauthenticate and/or reauthorize at the end of
   the period provided by the Authorization-Lifetime AVP.  The failure
   of a reauthentication exchange will terminate the service.

   Furthermore, it is possible for Diameter servers to issue an
   unsolicited reauthentication and/or reauthorization request (e.g.,
   Re-Auth-Request (RAR) message [BASE]) to the NAS.  Upon receipt of
   such a message, the NAS MUST respond to the request with a Re-Auth-
   Answer (RAA) message [BASE].

   If the RAR properly identifies an active session, the NAS will
   initiate a new local reauthentication or authorization sequence as
   indicated by the Re-Auth-Request-Type value.  This will cause the NAS
   to send a new AAR message using the existing Session-Id.  The server
   will respond with an AAA message to specify the new service
   parameters.

   If accounting is active, every change of authentication or
   authorization SHOULD generate an accounting message.  If the NAS
   service is a continuation of the prior user context, then an
   Accounting-Record-Type of INTERIM_RECORD indicating the new session
   attributes and cumulative status would be appropriate.  If a new user
   or a significant change in authorization is detected by the NAS, then
   the service may send two messages of the types STOP_RECORD and
   START_RECORD.  Accounting may change the subsession identifiers
   (Acct-Session-ID, or Acct-Sub-Session-Id) to indicate such sub-
   sessions.  A service may also use a different Session-Id value for
   accounting (see [BASE] section 9.6).

   However, the Diameter Session-ID AVP value used for the initial
   authorization exchange MUST be used to generate an STR message when
   the session context is terminated.

2.3.  Diameter Session Termination

   When a NAS receives an indication that a user's session is being
   disconnected by the client (e.g., LCP Terminate is received) or an
   administrative command, the NAS MUST issue a Session-Termination-
   Request (STR) [BASE] to its Diameter Server.  This will ensure that
   any resources maintained on the servers are freed appropriately.

   Furthermore, a NAS that receives an Abort-Session-Request (ASR)
   [BASE] MUST issue an ASA if the session identified is active and
   disconnect the PPP (or tunneling) session.




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   If accounting is active, an Accounting STOP_RECORD message [BASE]
   MUST be sent upon termination of the session context.

   More information on Diameter Session Termination is included in
   [BASE] sections 8.4 and 8.5.

3.  NAS Messages

   This section defines the Diameter message Command-Code [BASE] values
   that MUST be supported by all Diameter implementations conforming to
   this specification.  The Command Codes are as follows:

      Command-Name                  Abbrev.  Code   Reference
      -------------------------------------------------------
      AA-Request                      AAR     265     3.1
      AA-Answer                       AAA     265     3.2
      Re-Auth-Request                 RAR     258     3.3
      Re-Auth-Answer                  RAA     258     3.4
      Session-Termination-Request     STR     275     3.5
      Session-Termination-Answer      STA     275     3.6
      Abort-Session-Request           ASR     274     3.7
      Abort-Session-Answer            ASA     274     3.8
      Accounting-Request              ACR     271     3.9
      Accounting-Answer               ACA     271     3.10

3.1.  AA-Request (AAR) Command

   The AA-Request (AAR), which is indicated by setting the Command-Code
   field to 265 and the 'R' bit in the Command Flags field, is used to
   request authentication and/or authorization for a given NAS user.
   The type of request is identified through the Auth-Request-Type AVP
   [BASE].  The recommended value for most RADIUS interoperabily
   situations is AUTHORIZE_AUTHENTICATE.

   If Authentication is requested, the User-Name attribute SHOULD be
   present, as well as any additional authentication AVPs that would
   carry the password information.  A request for authorization SHOULD
   only include the information from which the authorization will be
   performed, such as the User-Name, Called-Station-Id, or Calling-
   Station-Id AVPs.  All requests SHOULD contain AVPs uniquely
   identifying the source of the call, such as Origin-Host and NAS-Port.
   Certain networks MAY use different AVPs for authorization purposes.
   A request for authorization will include some AVPs defined in section
   6.

   It is possible for a single session to be authorized first and then
   for an authentication request to follow.




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   This AA-Request message MAY be the result of a multi-round
   authentication exchange, which occurs when the AA-Answer message is
   received with the Result-Code AVP set to DIAMETER_MULTI_ROUND_AUTH.
   A subsequent AAR message SHOULD be sent, with the User-Password AVP
   that includes the user's response to the prompt, and MUST include any
   State AVPs that were present in the AAA message.

   Message Format
      <AA-Request> ::= < Diameter Header: 265, REQ, PXY >
                       < Session-Id >
                       { Auth-Application-Id }
                       { Origin-Host }
                       { Origin-Realm }
                       { Destination-Realm }
                       { Auth-Request-Type }
                       [ Destination-Host ]
                       [ NAS-Identifier ]
                       [ NAS-IP-Address ]
                       [ NAS-IPv6-Address ]
                       [ NAS-Port ]
                       [ NAS-Port-Id ]
                       [ NAS-Port-Type ]
                       [ Origin-AAA-Protocol ]
                       [ Origin-State-Id ]
                       [ Port-Limit ]
                       [ User-Name ]
                       [ User-Password ]
                       [ Service-Type ]
                       [ State ]
                       [ Authorization-Lifetime ]
                       [ Auth-Grace-Period ]
                       [ Auth-Session-State ]
                       [ Callback-Number ]
                       [ Called-Station-Id ]
                       [ Calling-Station-Id ]
                       [ Originating-Line-Info ]
                       [ Connect-Info ]
                       [ CHAP-Auth ]
                       [ CHAP-Challenge ]
                     * [ Framed-Compression ]
                       [ Framed-Interface-Id ]
                       [ Framed-IP-Address ]
                     * [ Framed-IPv6-Prefix ]
                       [ Framed-IP-Netmask ]
                       [ Framed-MTU ]
                       [ Framed-Protocol ]
                       [ ARAP-Password ]
                       [ ARAP-Security ]



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                     * [ ARAP-Security-Data ]
                     * [ Login-IP-Host ]
                     * [ Login-IPv6-Host ]
                       [ Login-LAT-Group ]
                       [ Login-LAT-Node ]
                       [ Login-LAT-Port ]
                       [ Login-LAT-Service ]
                     * [ Tunneling ]
                     * [ Proxy-Info ]
                     * [ Route-Record ]
                     * [ AVP ]

3.2.  AA-Answer (AAA) Command

   The AA-Answer (AAA) message is indicated by setting the Command-Code
   field to 265 and clearing the 'R' bit in the Command Flags field.  It
   is sent in response to the AA-Request (AAR) message.  If
   authorization was requested, a successful response will include the
   authorization AVPs appropriate for the service being provided, as
   defined in section 6.

   For authentication exchanges requiring more than a single round trip,
   the server MUST set the Result-Code AVP to DIAMETER_MULTI_ROUND_AUTH.
   An AAA message with this result code MAY include one Reply-Message or
   more and MAY include zero or one State AVPs.

   If the Reply-Message AVP was present, the network access server
   SHOULD send the text to the user's client to display to the user,
   instructing the client to prompt the user for a response.  For
   example, this capability can be achieved in PPP via PAP.  If the
   access client is unable to prompt the user for a new response, it
   MUST treat the AA-Answer (AAA) with the Reply-Message AVP as an error
   and deny access.

   Message Format

      <AA-Answer> ::= < Diameter Header: 265, PXY >
                      < Session-Id >
                      { Auth-Application-Id }
                      { Auth-Request-Type }
                      { Result-Code }
                      { Origin-Host }
                      { Origin-Realm }
                      [ User-Name ]
                      [ Service-Type ]
                    * [ Class ]
                    * [ Configuration-Token ]
                      [ Acct-Interim-Interval ]



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                      [ Error-Message ]
                      [ Error-Reporting-Host ]
                    * [ Failed-AVP ]
                      [ Idle-Timeout ]
                      [ Authorization-Lifetime ]
                      [ Auth-Grace-Period ]
                      [ Auth-Session-State ]
                      [ Re-Auth-Request-Type ]
                      [ Multi-Round-Time-Out ]
                      [ Session-Timeout ]
                      [ State ]
                    * [ Reply-Message ]
                      [ Origin-AAA-Protocol ]
                      [ Origin-State-Id ]
                    * [ Filter-Id ]
                      [ Password-Retry ]
                      [ Port-Limit ]
                      [ Prompt ]
                      [ ARAP-Challenge-Response ]
                      [ ARAP-Features ]
                      [ ARAP-Security ]
                    * [ ARAP-Security-Data ]
                      [ ARAP-Zone-Access ]
                      [ Callback-Id ]
                      [ Callback-Number ]
                      [ Framed-Appletalk-Link ]
                    * [ Framed-Appletalk-Network ]
                      [ Framed-Appletalk-Zone ]
                    * [ Framed-Compression ]
                      [ Framed-Interface-Id ]
                      [ Framed-IP-Address ]
                    * [ Framed-IPv6-Prefix ]
                      [ Framed-IPv6-Pool ]
                    * [ Framed-IPv6-Route ]
                      [ Framed-IP-Netmask ]
                    * [ Framed-Route ]
                      [ Framed-Pool ]
                      [ Framed-IPX-Network ]
                      [ Framed-MTU ]
                      [ Framed-Protocol ]
                      [ Framed-Routing ]
                    * [ Login-IP-Host ]
                    * [ Login-IPv6-Host ]
                      [ Login-LAT-Group ]
                      [ Login-LAT-Node ]
                      [ Login-LAT-Port ]
                      [ Login-LAT-Service ]
                      [ Login-Service ]



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                      [ Login-TCP-Port ]
                    * [ NAS-Filter-Rule ]
                    * [ QoS-Filter-Rule ]
                    * [ Tunneling ]
                    * [ Redirect-Host ]
                      [ Redirect-Host-Usage ]
                      [ Redirect-Max-Cache-Time ]
                    * [ Proxy-Info ]
                    * [ AVP ]

3.3.  Re-Auth-Request (RAR) Command

   A Diameter server may initiate a re-authentication and/or re-
   authorization service for a particular session by issuing a Re-Auth-
   Request (RAR) message [BASE].

   For example, for pre-paid services, the Diameter server that
   originally authorized a session may need some confirmation that the
   user is still using the services.

   If a NAS receives an RAR message with Session-Id equal to a currently
   active session and a Re-Auth-Type that includes authentication, it
   MUST initiate a re-authentication toward the user, if the service
   supports this particular feature.

   Message Format

      <RA-Request>  ::= < Diameter Header: 258, REQ, PXY >
                       < Session-Id >
                       { Origin-Host }
                       { Origin-Realm }
                       { Destination-Realm }
                       { Destination-Host }
                       { Auth-Application-Id }
                       { Re-Auth-Request-Type }
                       [ User-Name ]
                       [ Origin-AAA-Protocol ]
                       [ Origin-State-Id ]
                       [ NAS-Identifier ]
                       [ NAS-IP-Address ]
                       [ NAS-IPv6-Address ]
                       [ NAS-Port ]
                       [ NAS-Port-Id ]
                       [ NAS-Port-Type ]
                       [ Service-Type ]
                       [ Framed-IP-Address ]
                       [ Framed-IPv6-Prefix ]
                       [ Framed-Interface-Id ]



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                       [ Called-Station-Id ]
                       [ Calling-Station-Id ]
                       [ Originating-Line-Info ]
                       [ Acct-Session-Id ]
                       [ Acct-Multi-Session-Id ]
                       [ State ]
                     * [ Class ]
                       [ Reply-Message ]
                     * [ Proxy-Info ]
                     * [ Route-Record ]
                     * [ AVP ]

3.4.  Re-Auth-Answer (RAA) Command

   The Re-Auth-Answer (RAA) message [BASE] is sent in response to the
   RAR.  The Result-Code AVP MUST be present and indicates the
   disposition of the request.

   A successful RAA transaction MUST be followed by an AAR message.

   Message Format

      <RA-Answer>  ::= < Diameter Header: 258, PXY >
                       < Session-Id >
                       { Result-Code }
                       { Origin-Host }
                       { Origin-Realm }
                       [ User-Name ]
                       [ Origin-AAA-Protocol ]
                       [ Origin-State-Id ]
                       [ Error-Message ]
                       [ Error-Reporting-Host ]
                     * [ Failed-AVP ]
                     * [ Redirected-Host ]
                       [ Redirected-Host-Usage ]
                       [ Redirected-Host-Cache-Time ]
                       [ Service-Type ]
                     * [ Configuration-Token ]
                       [ Idle-Timeout ]
                       [ Authorization-Lifetime ]
                       [ Auth-Grace-Period ]
                       [ Re-Auth-Request-Type ]
                       [ State ]
                     * [ Class ]
                     * [ Reply-Message ]
                       [ Prompt ]
                     * [ Proxy-Info ]
                     * [ AVP ]



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3.5.  Session-Termination-Request (STR) Command

   The Session-Termination-Request (STR) message [BASE] is sent by the
   NAS to inform the Diameter Server that an authenticated and/or
   authorized session is being terminated.

   Message Format

      <ST-Request> ::= < Diameter Header: 275, REQ, PXY >
                      < Session-Id >
                      { Origin-Host }
                      { Origin-Realm }
                      { Destination-Realm }
                      { Auth-Application-Id }
                      { Termination-Cause }
                      [ User-Name ]
                      [ Destination-Host ]
                    * [ Class ]
                      [ Origin-AAA-Protocol ]
                      [ Origin-State-Id ]
                    * [ Proxy-Info ]
                    * [ Route-Record ]
                    * [ AVP ]

3.6.  Session-Termination-Answer (STA) Command

   The Session-Termination-Answer (STA) message [BASE] is sent by the
   Diameter Server to acknowledge the notification that the session has
   been terminated.  The Result-Code AVP MUST be present and MAY contain
   an indication that an error occurred while the STR was being
   serviced.

   Upon sending or receiving the STA, the Diameter Server MUST release
   all resources for the session indicated by the Session-Id AVP.  Any
   intermediate server in the Proxy-Chain MAY also release any
   resources, if necessary.

   Message Format

      <ST-Answer>  ::= < Diameter Header: 275, PXY >
                       < Session-Id >
                       { Result-Code }
                       { Origin-Host }
                       { Origin-Realm }
                       [ User-Name ]
                     * [ Class ]
                       [ Error-Message ]
                       [ Error-Reporting-Host ]



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                     * [ Failed-AVP ]
                       [ Origin-AAA-Protocol ]
                       [ Origin-State-Id ]
                     * [ Redirect-Host ]
                       [ Redirect-Host-Usase ]
                       [ Redirect-Max-Cache-Time ]
                     * [ Proxy-Info ]
                     * [ AVP ]

3.7.  Abort-Session-Request (ASR) Command

   The Abort-Session-Request (ASR) message [BASE] may be sent by any
   server to the NAS providing session service, to request that the
   session identified by the Session-Id be stopped.

   Message Format

      <AS-Request>  ::= < Diameter Header: 274, REQ, PXY >
                       < Session-Id >
                       { Origin-Host }
                       { Origin-Realm }
                       { Destination-Realm }
                       { Destination-Host }
                       { Auth-Application-Id }
                       [ User-Name ]
                       [ Origin-AAA-Protocol ]
                       [ Origin-State-Id ]
                       [ NAS-Identifier ]
                       [ NAS-IP-Address ]
                       [ NAS-IPv6-Address ]
                       [ NAS-Port ]
                       [ NAS-Port-Id ]
                       [ NAS-Port-Type ]
                       [ Service-Type ]
                       [ Framed-IP-Address ]
                       [ Framed-IPv6-Prefix ]
                       [ Framed-Interface-Id ]
                       [ Called-Station-Id ]
                       [ Calling-Station-Id ]
                       [ Originating-Line-Info ]
                       [ Acct-Session-Id ]
                       [ Acct-Multi-Session-Id ]
                       [ State ]
                     * [ Class ]
                     * [ Reply-Message ]
                     * [ Proxy-Info ]
                     * [ Route-Record ]
                     * [ AVP ]



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3.8.  Abort-Session-Answer (ASA) Command

   The ASA message [BASE] is sent in response to the ASR.  The Result-
   Code AVP MUST be present and indicates the disposition of the
   request.

   If the session identified by Session-Id in the ASR was successfully
   terminated, Result-Code is set to DIAMETER_SUCCESS.  If the session
   is not currently active, Result-Code is set to
   DIAMETER_UNKNOWN_SESSION_ID.  If the access device does not stop the
   session for any other reason, Result-Code is set to
   DIAMETER_UNABLE_TO_COMPLY.

   Message Format

      <AS-Answer>  ::= < Diameter Header: 274, PXY >
                       < Session-Id >
                       { Result-Code }
                       { Origin-Host }
                       { Origin-Realm }
                       [ User-Name ]
                       [ Origin-AAA-Protocol ]
                       [ Origin-State-Id ]
                       [ State]
                       [ Error-Message ]
                       [ Error-Reporting-Host ]
                     * [ Failed-AVP ]
                     * [ Redirected-Host ]
                       [ Redirected-Host-Usage ]
                       [ Redirected-Max-Cache-Time ]
                     * [ Proxy-Info ]
                     * [ AVP ]

3.9.  Accounting-Request (ACR) Command

   The ACR message [BASE] is sent by the NAS to report its session
   information to a target server downstream.

   Either of Acct-Application-Id or Vendor-Specific-Application-Id AVPs
   MUST be present.  If the Vendor-Specific-Application-Id grouped AVP
   is present, it must have an Acct-Application-Id inside.

   The AVPs listed in the Base MUST be assumed to be present, as
   appropriate.  NAS service-specific accounting AVPs SHOULD be present
   as described in section 8 and the rest of this specification.






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   Message Format

      <AC-Request> ::= < Diameter Header: 271, REQ, PXY >
                      < Session-Id >
                      { Origin-Host }
                      { Origin-Realm }
                      { Destination-Realm }
                      { Accounting-Record-Type }
                      { Accounting-Record-Number }
                      [ Acct-Application-Id ]
                      [ Vendor-Specific-Application-Id ]
                      [ User-Name ]
                      [ Accounting-Sub-Session-Id ]
                      [ Acct-Session-Id ]
                      [ Acct-Multi-Session-Id ]
                      [ Origin-AAA-Protocol ]
                      [ Origin-State-Id ]
                      [ Destination-Host ]
                      [ Event-Timestamp ]
                      [ Acct-Delay-Time ]
                      [ NAS-Identifier ]
                      [ NAS-IP-Address ]
                      [ NAS-IPv6-Address ]
                      [ NAS-Port ]
                      [ NAS-Port-Id ]
                      [ NAS-Port-Type ]
                    * [ Class ]
                      [ Service-Type ]
                      [ Termination-Cause ]
                      [ Accounting-Input-Octets ]
                      [ Accounting-Input-Packets ]
                      [ Accounting-Output-Octets ]
                      [ Accounting-Output-Packets ]
                      [ Acct-Authentic ]
                      [ Accounting-Auth-Method ]
                      [ Acct-Link-Count ]
                      [ Acct-Session-Time ]
                      [ Acct-Tunnel-Connection ]
                      [ Acct-Tunnel-Packets-Lost ]
                      [ Callback-Id ]
                      [ Callback-Number ]
                      [ Called-Station-Id ]
                      [ Calling-Station-Id ]
                    * [ Connection-Info ]
                      [ Originating-Line-Info ]
                      [ Authorization-Lifetime ]
                      [ Session-Timeout ]
                      [ Idle-Timeout ]



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                      [ Port-Limit ]
                      [ Accounting-Realtime-Required ]
                      [ Acct-Interim-Interval ]
                    * [ Filter-Id ]
                    * [ NAS-Filter-Rule ]
                    * [ Qos-Filter-Rule ]
                      [ Framed-AppleTalk-Link ]
                      [ Framed-AppleTalk-Network ]
                      [ Framed-AppleTalk-Zone ]
                      [ Framed-Compression ]
                      [ Framed-Interface-Id ]
                      [ Framed-IP-Address ]
                      [ Framed-IP-Netmask ]
                    * [ Framed-IPv6-Prefix ]
                      [ Framed-IPv6-Pool ]
                    * [ Framed-IPv6-Route ]
                      [ Framed-IPX-Network ]
                      [ Framed-MTU ]
                      [ Framed-Pool ]
                      [ Framed-Protocol ]
                    * [ Framed-Route ]
                      [ Framed-Routing ]
                    * [ Login-IP-Host ]
                    * [ Login-IPv6-Host ]
                      [ Login-LAT-Group ]
                      [ Login-LAT-Node ]
                      [ Login-LAT-Port ]
                      [ Login-LAT-Service ]
                      [ Login-Service ]
                      [ Login-TCP-Port ]
                    * [ Tunneling ]
                    * [ Proxy-Info ]
                    * [ Route-Record ]
                    * [ AVP ]

3.10.  Accounting-Answer (ACA) Command

   The ACA message [BASE] is used to acknowledge an Accounting-Request
   command.  The Accounting-Answer command contains the same Session-Id
   as the Request.  If the Accounting-Request was protected by end-to-
   end security, then the corresponding ACA message MUST be protected as
   well.

   Only the target Diameter Server or home Diameter Server SHOULD
   respond with the Accounting-Answer command.

   Either Acct-Application-Id or Vendor-Specific-Application-Id AVPs
   MUST be present, as it was in the request.



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   The AVPs listed in the Base MUST be assumed to be present, as
   appropriate.  NAS service-specific accounting AVPs SHOULD be present
   as described in section 8 and the rest of this specification.

   Message Format

      <AC-Answer> ::= < Diameter Header: 271, PXY >
                      < Session-Id >
                      { Result-Code }
                      { Origin-Host }
                      { Origin-Realm }
                      { Accounting-Record-Type }
                      { Accounting-Record-Number }
                      [ Acct-Application-Id ]
                      [ Vendor-Specific-Application-Id ]
                      [ User-Name ]
                      [ Accounting-Sub-Session-Id ]
                      [ Acct-Session-Id ]
                      [ Acct-Multi-Session-Id ]
                      [ Event-Timestamp ]
                      [ Error-Message ]
                      [ Error-Reporting-Host ]
                    * [ Failed-AVP ]
                      [ Origin-AAA-Protocol ]
                      [ Origin-State-Id ]
                      [ NAS-Identifier ]
                      [ NAS-IP-Address ]
                      [ NAS-IPv6-Address ]
                      [ NAS-Port ]
                      [ NAS-Port-Id ]
                      [ NAS-Port-Type ]
                      [ Service-Type ]
                      [ Termination-Cause ]
                      [ Accounting-Realtime-Required ]
                      [ Acct-Interim-Interval ]
                    * [ Class ]
                    * [ Proxy-Info ]
                    * [ Route-Record ]
                    * [ AVP ]

4.  NAS Session AVPs

   Diameter reserves the AVP Codes 0 - 255 for RADIUS functions that are
   implemented in Diameter.

   AVPs new to Diameter have code values of 256 and greater.  A Diameter
   message that includes one of these AVPs may represent functions not
   present in the RADIUS environment and may cause interoperability



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   issues, should the request traverse an AAA system that only supports
   the RADIUS protocol.

   Some RADIUS attributes are not allowed or supported directly in
   Diameter.  See section 9 for more information.

4.1.  Call and Session Information

   This section contains the AVPs specific to NAS Diameter applications
   that are needed to identify the call and session context and status
   information.  On a request, this information allows the server to
   qualify the session.

   These AVPs are used in addition to the Base AVPs of:

      Session-Id
      Auth-Application-Id
      Origin-Host
      Origin-Realm
      Auth-Request-Type
      Termination-Cause

   The following table describes the session level AVPs; their AVP Code
   values, types, and possible flag values; and whether the AVP MAY be
   encrypted.

                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|    |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
   -----------------------------------------|----+-----+----+-----|----|
   NAS-Port           5   4.2    Unsigned32 | M  |  P  |    |  V  | Y  |
   NAS-Port-Id       87   4.3    UTF8String | M  |  P  |    |  V  | Y  |
   NAS-Port-Type     61   4.4    Enumerated | M  |  P  |    |  V  | Y  |
   Called-Station-Id 30   4.5    UTF8String | M  |  P  |    |  V  | Y  |
   Calling-Station-  31   4.6    UTF8String | M  |  P  |    |  V  | Y  |
     Id                                     |    |     |    |     |    |
   Connect-Info      77   4.7    UTF8String | M  |  P  |    |  V  | Y  |
   Originating-Line- 94   4.8    OctetString|    | M,P |    |  V  | Y  |
     Info                                   |    |     |    |     |    |
   Reply-Message     18   4.9    UTF8String | M  |  P  |    |  V  | Y  |
   -----------------------------------------|----+-----+----+-----|----|








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4.2.  NAS-Port AVP

   The NAS-Port AVP (AVP Code 5) is of type Unsigned32 and contains the
   physical or virtual port number of the NAS which is authenticating
   the user.  Note that "port" is meant in its sense as a service
   connection on the NAS, not as an IP protocol identifier.

   Either NAS-Port or NAS-Port-Id (AVP Code 87) SHOULD be present in
   AA-Request (AAR) commands if the NAS differentiates among its ports.

4.3.  NAS-Port-Id AVP

   The NAS-Port-Id AVP (AVP Code 87) is of type UTF8String and consists
   of ASCII text identifying the port of the NAS authenticating the
   user.  Note that "port" is meant in its sense as a service connection
   on the NAS, not as an IP protocol identifier.

   Either NAS-Port or NAS-Port-Id SHOULD be present in AA-Request (AAR)
   commands if the NAS differentiates among its ports.  NAS-Port-Id is
   intended for use by NASes that cannot conveniently number their
   ports.

4.4.  NAS-Port-Type AVP

   The NAS-Port-Type AVP (AVP Code 61) is of type Enumerated and
   contains the type of the port on which the NAS is authenticating the
   user.  This AVP SHOULD be present if the NAS uses the same NAS-Port
   number ranges for different service types concurrently.

   The supported values are defined in [RADIUSTypes].  The following
   list is informational and subject to change by the IANA.

       0   Async
       1   Sync
       2   ISDN Sync
       3   ISDN Async V.120
       4   ISDN Async V.110
       5   Virtual
       6   PIAFS
       7   HDLC Clear Channel
       8   X.25
       9   X.75
      10   G.3 Fax
      11   SDSL - Symmetric DSL
      12   ADSL-CAP - Asymmetric DSL, Carrierless Amplitude Phase
              Modulation
      13   ADSL-DMT - Asymmetric DSL, Discrete Multi-Tone
      14   IDSL - ISDN Digital Subscriber Line



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      15   Ethernet
      16   xDSL - Digital Subscriber Line of unknown type
      17   Cable
      18   Wireless - Other
      19   Wireless - IEEE 802.11
      20   Token-Ring   [RAD802.1X]
      21   FDDI         [RAD802.1X]
      22   Wireless - CDMA2000
      23   Wireless - UMTS
      24   Wireless - 1X-EV
      25   IAPP    [IEEE 802.11f]

4.5.  Called-Station-Id AVP

   The Called-Station-Id AVP (AVP Code 30) is of type UTF8String and
   allows the NAS to send the ASCII string describing the layer 2
   address the user contacted in the request.  For dialup access, this
   can be a phone number obtained by using Dialed Number Identification
   (DNIS) or a similar technology.  Note that this may be different from
   the phone number the call comes in on.  For use with IEEE 802 access,
   the Called-Station-Id MAY contain a MAC address formatted as
   described in [RAD802.1X].  It SHOULD only be present in
   authentication and/or authorization requests.

   If the Auth-Request-Type AVP is set to authorization-only and the
   User-Name AVP is absent, the Diameter Server MAY perform
   authorization based on this field.  This can be used by a NAS to
   request whether a call should be answered based on the DNIS.

   The codification of this field's allowed usage range is outside the
   scope of this specification.

4.6.  Calling-Station-Id AVP

   The Calling-Station-Id AVP (AVP Code 31) is of type UTF8String and
   allows the NAS to send the ASCII string describing the layer 2
   address from which the user connected in the request.  For dialup
   access, this is the phone number the call came from, using Automatic
   Number Identification (ANI) or a similar technology.  For use with
   IEEE 802 access, the Calling-Station-Id AVP MAY contain a MAC
   address, formated as described in [RAD802.1X].  It SHOULD only be
   present in authentication and/or authorization requests.

   If the Auth-Request-Type AVP is set to authorization-only and the
   User-Name AVP is absent, the Diameter Server MAY perform
   authorization based on this field.  This can be used by a NAS to
   request whether a call should be answered based on the layer 2
   address (ANI, MAC Address, etc.)



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   The codification of this field's allowed usage range is outside the
   scope of this specification.

4.7.  Connect-Info AVP

   The Connect-Info AVP (AVP Code 77) is of type UTF8String and is sent
   in the AA-Request message or ACR STOP message.  When sent in the
   Access-Request, it indicates the nature of the user's connection.
   The connection speed SHOULD be included at the beginning of the first
   Connect-Info AVP in the message.  If the transmit and receive
   connection speeds differ, both may be included in the first AVP with
   the transmit speed listed first (the speed the NAS modem transmits
   at), then a slash (/), then the receive speed, and then other
   optional information.

   For example: "28800 V42BIS/LAPM" or "52000/31200 V90"

   More than one Connect-Info attribute may be present in an
   Accounting-Request packet to accommodate expected efforts by the ITU
   to have modems report more connection information in a standard
   format that might exceed 252 octets.

   If sent in the ACR STOP, this attribute may summarize statistics
   relating to session quality.  For example, in IEEE 802.11, the
   Connect-Info attribute may contain information on the number of link
   layer retransmissions.  The exact format of this attribute is
   implementation specific.

4.8.  Originating-Line-Info AVP

   The Originating-Line-Info AVP (AVP Code 94) is of type OctetString
   and is sent by the NAS system to convey information about the origin
   of the call from an SS7 system.

   The originating line information (OLI) element indicates the nature
   and/or characteristics of the line from which a call originated
   (e.g., pay phone, hotel, cellular).  Telephone companies are starting
   to offer OLI to their customers as an option over Primary Rate
   Interface (PRI).  Internet Service Providers (ISPs) can use OLI in
   addition to Called-Station-Id and Calling-Station-Id attributes to
   differentiate customer calls and to define different services.

   The Value field contains two octets (00 - 99).  ANSI T1.113 and
   BELLCORE 394 can be used for additional information about these
   values and their use.  For more information on current assignment
   values, see [ANITypes].





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    Value   Description
   ------------------------------------------------------------
      00    Plain Old Telephone Service (POTS)
      01    Multiparty Line (more than 2)
      02    ANI Failure
      03    ANI Observed
      04    ONI Observed
      05    ANI Failure Observed
      06    Station Level Rating
      07    Special Operator Handling Required
      08    InterLATA Restricted
      10    Test Call
      20    Automatic Identified Outward Dialing (AIOD)
      23    Coin or Non-Coin
      24    Toll Free Service (Non-Pay Origination)
      25    Toll Free Service (Pay Origination)
      27    Toll Free Service (Coin Control Origination)
      29    Prison/Inmate Service
      30-32 Intercept
      30    Intercept (Blank)
      31    Intercept (Trouble)
      32    Intercept (Regular)
      34    Telco Operator Handled Call
      40-49 Unrestricted Use
      52    Outward Wide Area Telecommunications Service (OUTWATS)
      60    Telecommunications Relay Service (TRS)(Unrestricted)
      61    Cellular/Wireless PCS (Type 1)
      62    Cellular/Wireless PCS (Type 2)
      63    Cellular/Wireless PCS (Roaming)
      66    TRS (Hotel)
      67    TRS (Restricted)
      70    Pay Station, No Coin Control
      93    Access for Private Virtual Network Service

4.9.  Reply-Message AVP

   The Reply-Message AVP (AVP Code 18) is of type UTF8String and
   contains text that MAY be displayed to the user.  When used in an
   AA-Answer message with a successful Result-Code AVP, it indicates
   success.  When found in an AAA message with a Result-Code other than
   DIAMETER_SUCCESS, the AVP contains a failure message.

   The Reply-Message AVP MAY indicate dialog text to prompt the user
   before another AA-Request attempt.  When used in an AA-Answer with a
   Result-Code of DIAMETER_MULTI_ROUND_AUTH or in an Re-Auth-Request
   message, it MAY contain a dialog text to prompt the user for a
   response.




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   Multiple Reply-Messages MAY be included, and if any are displayed,
   they MUST be displayed in the same order as they appear in the
   Diameter message.

5.  NAS Authentication AVPs

   This section defines the AVPs necessary to carry the authentication
   information in the Diameter protocol.  The functionality defined here
   provides a RADIUS-like AAA service over a more reliable and secure
   transport, as defined in the base protocol [BASE].

   The following table describes the AVPs; their AVP Code values, types,
   and possible flag values, and whether the AVP MAY be encrypted.

                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|    |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
   -----------------------------------------|----+-----+----+-----|----|
   User-Password      2   5.1    OctetString| M  |  P  |    |  V  | Y  |
   Password-Retry    75   5.2    Unsigned32 | M  |  P  |    |  V  | Y  |
   Prompt            76   5.3    Enumerated | M  |  P  |    |  V  | Y  |
   CHAP-Auth        402   5.4    Grouped    | M  |  P  |    |  V  | Y  |
   CHAP-Algorithm   403   5.5    Enumerated | M  |  P  |    |  V  | Y  |
   CHAP-Ident       404   5.6    OctetString| M  |  P  |    |  V  | Y  |
   CHAP-Response    405   5.7    OctetString| M  |  P  |    |  V  | Y  |
   CHAP-Challenge    60   5.8    OctetString| M  |  P  |    |  V  | Y  |
   ARAP-Password     70   5.9    OctetString| M  |  P  |    |  V  | Y  |
   ARAP-Challenge-   84   5.10   OctetString| M  |  P  |    |  V  | Y  |
     Response                               |    |     |    |     |    |
   ARAP-Security     73   5.11   Unsigned32 | M  |  P  |    |  V  | Y  |
   ARAP-Security-    74   5.12   OctetString| M  |  P  |    |  V  | Y  |
     Data                                   |    |     |    |     |    |
   -----------------------------------------|----+-----+----+-----|----|

5.1.  User-Password AVP

   The User-Password AVP (AVP Code 2) is of type OctetString and
   contains the password of the user to be authenticated, or the user's
   input in a multi-round authentication exchange.

   The User-Password AVP contains a user password or one-time password
   and therefore represents sensitive information.  As required in
   [BASE], Diameter messages are encrypted by using IPsec or TLS.
   Unless this AVP is used for one-time passwords, the User-Password AVP





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   SHOULD NOT be used in untrusted proxy environments without encrypting
   it by using end-to-end security techniques, such as the proposed CMS
   Security [DiamCMS].

   The clear-text password (prior to encryption) MUST NOT be longer than
   128 bytes in length.

5.2.  Password-Retry AVP

   The Password-Retry AVP (AVP Code 75) is of type Unsigned32 and MAY be
   included in the AA-Answer if the Result-Code indicates an
   authentication failure.  The value of this AVP indicates how many
   authentication attempts a user is permitted before being
   disconnected.  This AVP is primarily intended for use when the
   Framed-Protocol AVP (see section 6.10.1) is set to ARAP.

5.3.  Prompt AVP

   The Prompt AVP (AVP Code 76) is of type Enumerated and MAY be present
   in the AA-Answer message.  When present, it is used by the NAS to
   determine whether the user's response, when entered, should be
   echoed.

   The supported values are listed in [RADIUSTypes].  The following list
   is informational:

      0  No Echo
      1  Echo

5.4.  CHAP-Auth AVP

   The CHAP-Auth AVP (AVP Code 402) is of type Grouped and contains the
   information necessary to authenticate a user using the PPP
   Challenge-Handshake Authentication Protocol (CHAP) [PPPCHAP].  If the
   CHAP-Auth AVP is found in a message, the CHAP-Challenge AVP MUST be
   present as well.  The optional AVPs containing the CHAP response
   depend upon the value of the CHAP-Algorithm AVP.  The grouped AVP has
   the following ABNF grammar:

      CHAP-Auth  ::= < AVP Header: 402 >
                     { CHAP-Algorithm }
                     { CHAP-Ident }
                     [ CHAP-Response ]
                   * [ AVP ]







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5.5.  CHAP-Algorithm AVP

   The CHAP-Algorithm AVP (AVP Code 403) is of type Enumerated and
   contains the algorithm identifier used in the computation of the CHAP
   response [PPPCHAP].  The following values are currently supported:

      CHAP with MD5       5
         The CHAP response is computed by using the procedure described
         in [PPPCHAP].  This algorithm requires that the CHAP-Response
         AVP MUST be present in the CHAP-Auth AVP.

5.6.  CHAP-Ident AVP

   The CHAP-Ident AVP (AVP Code 404) is of type OctetString and contains
   the 1 octet CHAP Identifier used in the computation of the CHAP
   response [PPPCHAP].

5.7.  CHAP-Response AVP

   The CHAP-Response AVP (AVP Code 405) is of type OctetString and
   contains the 16 octet authentication data provided by the user in
   response to the CHAP challenge [PPPCHAP].

5.8.  CHAP-Challenge AVP

   The CHAP-Challenge AVP (AVP Code 60) is of type OctetString and
   contains the CHAP Challenge sent by the NAS to the CHAP peer
   [PPPCHAP].

5.9.  ARAP-Password AVP

   The ARAP-Password AVP (AVP Code 70) is of type OctetString and is
   only present when the Framed-Protocol AVP (see section 6.10.1) is
   included in the message and is set to ARAP.  This AVP MUST NOT be
   present if either the User-Password or the CHAP-Auth AVP is present.
   See [RADIUSExt] for more information on the contents of this AVP.

5.10.  ARAP-Challenge-Response AVP

   The ARAP-Challenge-Response AVP (AVP Code 84) is of type OctetString
   and is only present when the Framed-Protocol AVP (see section 6.10.1)
   is included in the message and is set to ARAP.  This AVP contains an
   8 octet response to the dial-in client's challenge.  The RADIUS
   server calculates this value by taking the dial-in client's challenge
   from the high-order 8 octets of the ARAP-Password AVP and performing
   DES encryption on this value with the authenticating user's password





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   as the key.  If the user's password is fewer than 8 octets in length,
   the password is padded at the end with NULL octets to a length of 8
   before it is used as a key.

5.11.  ARAP-Security AVP

   The ARAP-Security AVP (AVP Code 73) is of type Unsigned32 and MAY be
   present in the AA-Answer message if the Framed-Protocol AVP (see
   section 6.10.1) is set to the value of ARAP, and the Result-Code AVP
   is set to DIAMETER_MULTI_ROUND_AUTH.  See [RADIUSExt] for more
   information on the format of this AVP.

5.12.  ARAP-Security-Data AVP

   The ARAP-Security AVP (AVP Code 74) is of type OctetString and MAY be
   present in the AA-Request or AA-Answer message if the Framed-Protocol
   AVP is set to the value of ARAP, and the Result-Code AVP is set to
   DIAMETER_MULTI_ROUND_AUTH.  This AVP contains the security module
   challenge or response associated with the ARAP Security Module
   specified in ARAP-Security.

6.  NAS Authorization AVPs

   This section contains the authorization AVPs supported in the NAS
   Application.  The Service-Type AVP SHOULD be present in all messages,
   and, based on its value, additional AVPs defined in this section and
   in section 7 MAY be present.

   Due to space constraints, the short-form IPFltrRule is used to
   represent IPFilterRule, and QoSFltrRule is used for QoSFilterRule.

                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|    |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
   -----------------------------------------|----+-----+----+-----|----|
   Service-Type       6   6.1    Enumerated | M  |  P  |    |  V  | Y  |
   Callback-Number   19   6.2    UTF8String | M  |  P  |    |  V  | Y  |
   Callback-Id       20   6.3    UTF8String | M  |  P  |    |  V  | Y  |
   Idle-Timeout      28   6.4    Unsigned32 | M  |  P  |    |  V  | Y  |
   Port-Limit        62   6.5    Unsigned32 | M  |  P  |    |  V  | Y  |
   NAS-Filter-Rule  400   6.6    IPFltrRule | M  |  P  |    |  V  | Y  |
   Filter-Id         11   6.7    UTF8String | M  |  P  |    |  V  | Y  |
   Configuration-    78   6.8    OctetString| M  |     |    | P,V |    |
     Token                                  |    |     |    |     |    |
   QoS-Filter-Rule  407   6.9    QoSFltrRule|    |     |    |     |    |
   Framed-Protocol    7  6.10.1  Enumerated | M  |  P  |    |  V  | Y  |



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   Framed-Routing    10  6.10.2  Enumerated | M  |  P  |    |  V  | Y  |
   Framed-MTU        12  6.10.3  Unsigned32 | M  |  P  |    |  V  | Y  |
   Framed-           13  6.10.4  Enumerated | M  |  P  |    |  V  | Y  |
     Compression                            |    |     |    |     |    |
   Framed-IP-Address  8  6.11.1  OctetString| M  |  P  |    |  V  | Y  |
   Framed-IP-Netmask  9  6.11.2  OctetString| M  |  P  |    |  V  | Y  |
   Framed-Route      22  6.11.3  UTF8String | M  |  P  |    |  V  | Y  |
   Framed-Pool       88  6.11.4  OctetString| M  |  P  |    |  V  | Y  |
   Framed-           96  6.11.5  Unsigned64 | M  |  P  |    |  V  | Y  |
     Interface-Id                           |    |     |    |     |    |
   Framed-IPv6-      97  6.11.6  OctetString| M  |  P  |    |  V  | Y  |
     Prefix                                 |    |     |    |     |    |
   Framed-IPv6-      99  6.11.7  UTF8String | M  |  P  |    |  V  | Y  |
     Route                                  |    |     |    |     |    |
   Framed-IPv6-Pool 100  6.11.8  OctetString| M  |  P  |    |  V  | Y  |
   Framed-IPX-       23  6.12.1  UTF8String | M  |  P  |    |  V  | Y  |
     Network                                |    |     |    |     |    |
   Framed-Appletalk- 37  6.13.1  Unsigned32 | M  |  P  |    |  V  | Y  |
     Link                                   |    |     |    |     |    |
   Framed-Appletalk- 38  6.13.2  Unsigned32 | M  |  P  |    |  V  | Y  |
     Network                                |    |     |    |     |    |
   Framed-Appletalk- 39  6.13.3  OctetString| M  |  P  |    |  V  | Y  |
     Zone                                   |    |     |    |     |    |
   ARAP-Features     71  6.14.1  OctetString| M  |  P  |    |  V  | Y  |
   ARAP-Zone-Access  72  6.14.2  Enumerated | M  |  P  |    |  V  | Y  |
   Login-IP-Host     14  6.15.1  OctetString| M  |  P  |    |  V  | Y  |
   Login-IPv6-Host   98  6.15.2  OctetString| M  |  P  |    |  V  | Y  |
   Login-Service     15  6.15.3  Enumerated | M  |  P  |    |  V  | Y  |
   Login-TCP-Port    16  6.16.1  Unsigned32 | M  |  P  |    |  V  | Y  |
   Login-LAT-Service 34  6.17.1  OctetString| M  |  P  |    |  V  | Y  |
   Login-LAT-Node    35  6.17.2  OctetString| M  |  P  |    |  V  | Y  |
   Login-LAT-Group   36  6.17.3  OctetString| M  |  P  |    |  V  | Y  |
   Login-LAT-Port    63  6.17.4  OctetString| M  |  P  |    |  V  | Y  |
   -----------------------------------------|----+-----+----+-----|----|

6.1.  Service-Type AVP

   The Service-Type AVP (AVP Code 6) is of type Enumerated and contains
   the type of service the user has requested or the type of service to
   be provided.  One such AVP MAY be present in an authentication and/or
   authorization request or response.  A NAS is not required to
   implement all of these service types.  It MUST treat unknown or
   unsupported Service-Types received in a response as a failure and end
   the session with a DIAMETER_INVALID_AVP_VALUE Result-Code.

   When used in a request, the Service-Type AVP SHOULD be considered a
   hint to the server that the NAS believes the user would prefer the
   kind of service indicated.  The server is not required to honor the



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   hint.  Furthermore, if the service specified by the server is
   supported, but not compatible with the current mode of access, the
   NAS MUST fail to start the session.  The NAS MUST also generate the
   appropriate error message(s).

   The following values have been defined for the Service-Type AVP.  The
   complete list of defined values can be found in [RADIUS] and
   [RADIUSTypes].  The following list is informational:

       1  Login
       2  Framed
       3  Callback Login
       4  Callback Framed
       5  Outbound
       6  Administrative
       7  NAS Prompt
       8  Authenticate Only
       9  Callback NAS Prompt
      10  Call Check
      11  Callback Administrative
      12  Voice
      13  Fax
      14  Modem Relay
      15  IAPP-Register   [IEEE 802.11f]
      16  IAPP-AP-Check   [IEEE 802.11f]
      17  Authorize Only  [RADDynAuth]

   The following values are further qualified:

      Login               1
         The user should be connected to a host.  The message MAY
         include additional AVPs defined in sections 6.16 or 6.17.

      Framed              2
         A Framed Protocol, such as PPP or SLIP, should be started for
         the User.  The message MAY include additional AVPs defined in
         section 6.10, or section 7 for tunneling services.

      Callback Login      3
         The user should be disconnected and called back, then connected
         to a host.  The message MAY include additional AVPs defined in
         this section.

      Callback Framed     4
         The user should be disconnected and called back, and then a
         Framed Protocol, such as PPP or SLIP, should be started for the
         User.  The message MAY include additional AVPs defined in
         section 6.10, or in section 7 for tunneling services.



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6.2.  Callback-Number AVP

   The Callback-Number AVP (AVP Code 19) is of type UTF8String and
   contains a dialing string to be used for callback.  It MAY be used in
   an authentication and/or authorization request as a hint to the
   server that a Callback service is desired, but the server is not
   required to honor the hint in the corresponding response.

   The codification of this field's allowed usage range is outside the
   scope of this specification.

6.3.  Callback-Id AVP

   The Callback-Id AVP (AVP Code 20) is of type UTF8String and contains
   the name of a place to be called, to be interpreted by the NAS.  This
   AVP MAY be present in an authentication and/or authorization
   response.

   This AVP is not roaming-friendly as it assumes that the Callback-Id
   is configured on the NAS.  Using the Callback-Number AVP therefore
   preferable.

6.4.  Idle-Timeout AVP

   The Idle-Timeout AVP (AVP Code 28) is of type Unsigned32 and sets the
   maximum number of consecutive seconds of idle connection allowable to
   the user before termination of the session or before a prompt is
   issued.  The default is none, or system specific.

6.5.  Port-Limit AVP

   The Port-Limit AVP (AVP Code 62) is of type Unsigned32 and sets the
   maximum number of ports the NAS provides to the user.  It MAY be used
   in an authentication and/or authorization request as a hint to the
   server that multilink PPP [PPPMP] service is desired, but the server
   is not required to honor the hint in the corresponding response.

6.6.  NAS-Filter-Rule AVP

   The NAS-Filter-Rule AVP (AVP Code 400) is of type IPFilterRule and
   provides filter rules that need to be configured on the NAS for the
   user.  One or more of these AVPs MAY be present in an authorization
   response.








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6.7.  Filter-Id AVP

   The Filter-Id AVP (AVP Code 11) is of type UTF8String and contains
   the name of the filter list for this user.  Zero or more Filter-Id
   AVPs MAY be sent in an authorization answer.

   Identifying a filter list by name allows the filter to be used on
   different NASes without regard to filter-list implementation details.
   However, this AVP is not roaming friendly, as filter naming differs
   from one service provider to another.

   In non-RADIUS environments, it is RECOMMENDED that the NAS-Filter-
   Rule AVP be used instead.

6.8.  Configuration-Token AVP

   The Configuration-Token AVP (AVP Code 78) is of type OctetString and
   is sent by a Diameter Server to a Diameter Proxy Agent or Translation
   Agent in an AA-Answer command to indicate a type of user profile to
   be used.  It should not be sent to a Diameter Client (NAS).

   The format of the Data field of this AVP is site specific.

6.9.  QoS-Filter-Rule AVP

   The QoS-Filter-Rule AVP (AVP Code 407) is of type QoSFilterRule and
   provides QoS filter rules that need to be configured on the NAS for
   the user.  One or more such AVPs MAY be present in an authorization
   response.

   Note: Due to an editorial mistake in [BASE], only the AVP format is
   discussed.  The complete QoSFilterRule definition was not included.
   It is reprinted here for clarification.

   QoSFilterRule

      The QosFilterRule format is derived from the OctetString AVP Base
      Format.  It uses the ASCII charset.  Packets may be marked or
      metered based on the following information:

         Direction                          (in or out)
         Source and destination IP address  (possibly masked)
         Protocol
         Source and destination port        (lists or ranges)
         DSCP values                        (no mask or range)

      Rules for the appropriate direction are evaluated in order; the
      first matched rule terminates the evaluation.  Each packet is



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      evaluated once.  If no rule matches, the packet is treated as best
      effort.  An access device unable to interpret or apply a QoS rule
      SHOULD NOT terminate the session.

   QoSFilterRule filters MUST follow the following format:

      action dir proto from src to dst [options]

                tag    - Mark packet with a specific DSCP
                         [DIFFSERV].  The DSCP option MUST be
                         included.
                meter  - Meter traffic.  The metering options
                         MUST be included.

   dir           The format is as described under IPFilterRule.

   proto         The format is as described under IPFilterRule.

   src and dst   The format is as described under IPFilterRule.

         options:

         DSCP <color>
               Color values as defined in [DIFFSERV].  Exact
               matching of DSCP values is required (no masks or
               ranges).

         metering <rate> <color_under> <color_over>
               The metering option provides Assured Forwarding,
               as defined in [DIFFSERVAF], and MUST be present
               if the action is set to meter.  The rate option is
               the throughput, in bits per second, used
               by the access device to mark packets.  Traffic
               over the rate is marked with the color_over
               codepoint, and traffic under the rate is marked
               with the color_under codepoint.  The color_under
               and color_over options contain the drop
               preferences and MUST conform to the recommended
               codepoint keywords described in [DIFFSERVAF]
               (e.g., AF13).

               The metering option also supports the strict
               limit on traffic required by Expedited
               Forwarding, as defined in [DIFFSERVEF].  The
               color_over option may contain the keyword "drop"
               to prevent forwarding of traffic that exceeds the
               rate parameter.




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         The rule syntax is a modified subset of ipfw(8) from FreeBSD,
         and the ipfw.c code may provide a useful base for
         implementations.

6.10.  Framed Access Authorization AVPs

   This section lists the authorization AVPs necessary to
   support framed access, such as PPP and SLIP.  AVPs defined in this
   section MAY be present in a message if the Service-Type AVP was set
   to "Framed" or "Callback Framed".

6.10.1.  Framed-Protocol AVP

   The Framed-Protocol AVP (AVP Code 7) is of type Enumerated and
   contains the framing to be used for framed access.  This AVP MAY be
   present in both requests and responses.  The supported values are
   listed in [RADIUSTypes].  The following list is informational:

      1  PPP
      2  SLIP
      3  AppleTalk Remote Access Protocol (ARAP)
      4  Gandalf proprietary SingleLink/MultiLink protocol
      5  Xylogics proprietary IPX/SLIP
      6  X.75 Synchronous

6.10.2.  Framed-Routing AVP

   The Framed-Routing AVP (AVP Code 10) is of type Enumerated and
   contains the routing method for the user when the user is a router to
   a network.  This AVP SHOULD only be present in authorization
   responses.  The supported values are listed in [RADIUSTypes].  The
   following list is informational:

      0  None
      1  Send routing packets
      2  Listen for routing packets
      3  Send and Listen

6.10.3.  Framed-MTU AVP

   The Framed-MTU AVP (AVP Code 12) is of type Unsigned32 and contains
   the Maximum Transmission Unit to be configured for the user, when it
   is not negotiated by some other means (such as PPP).  This AVP SHOULD
   only be present in authorization responses.  The MTU value MUST be in
   the range from 64 to 65535.






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6.10.4.  Framed-Compression AVP

   The Framed-Compression AVP (AVP Code 13) is of type Enumerated and
   contains the compression protocol to be used for the link.  It MAY be
   used in an authorization request as a hint to the server that a
   specific compression type is desired, but the server is not required
   to honor the hint in the corresponding response.

   More than one compression protocol AVP MAY be sent.  The NAS is
   responsible for applying the proper compression protocol to the
   appropriate link traffic.

   The supported values are listed in [RADIUSTypes].  The following list
   is informational:

      0  None
      1  VJ TCP/IP header compression
      2  IPX header compression
      3  Stac-LZS compression

6.11.  IP Access Authorization AVPs

   The AVPs defined in this section are used when the user requests, or
   is being granted, access service to IP.

6.11.1.  Framed-IP-Address AVP

   The Framed-IP-Address AVP (AVP Code 8) [RADIUS] is of type
   OctetString and contains an IPv4 address of the type specified in the
   attribute value to be configured for the user.  It MAY be used in an
   authorization request as a hint to the server that a specific address
   is desired, but the server is not required to honor the hint in the
   corresponding response.

   Two values have special significance: 0xFFFFFFFF and 0xFFFFFFFE.  The
   value 0xFFFFFFFF indicates that the NAS should allow the user to
   select an address (i.e., negotiated).  The value 0xFFFFFFFE indicates
   that the NAS should select an address for the user (e.g., assigned
   from a pool of addresses kept by the NAS).

6.11.2.  Framed-IP-Netmask AVP

   The Framed-IP-Netmask AVP (AVP Code 9) is of type OctetString and
   contains the four octets of the IPv4 netmask to be configured for the
   user when the user is a router to a network.  It MAY be used in an
   authorization request as a hint to the server that a specific netmask





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   is desired, but the server is not required to honor the hint in the
   corresponding response.  This AVP MUST be present in a response if
   the request included this AVP with a value of 0xFFFFFFFF.

6.11.3.  Framed-Route AVP

   The Framed-Route AVP (AVP Code 22) is of type UTF8String and contains
   the ASCII routing information to be configured for the user on the
   NAS.  Zero or more of these AVPs MAY be present in an authorization
   response.

   The string MUST contain a destination prefix in dotted quad form
   optionally followed by a slash and a decimal length specifier stating
   how many high-order bits of the prefix should be used.  This is
   followed by a space, a gateway address in dotted quad form, a space,
   and one or more metrics separated by spaces; for example,

      "192.168.1.0/24 192.168.1.1 1".

   The length specifier may be omitted, in which case it should default
   to 8 bits for class A prefixes, to 16 bits for class B prefixes, and
   to 24 bits for class C prefixes; for example,

      "192.168.1.0 192.168.1.1 1".

   Whenever the gateway address is specified as "0.0.0.0" the IP address
   of the user SHOULD be used as the gateway address.

6.11.4.  Framed-Pool AVP

   The Framed-Pool AVP (AVP Code 88) is of type OctetString and contains
   the name of an assigned address pool that SHOULD be used to assign an
   address for the user.  If a NAS does not support multiple address
   pools, the NAS SHOULD ignore this AVP.  Address pools are usually
   used for IP addresses but can be used for other protocols if the NAS
   supports pools for those protocols.

   Although specified as type OctetString for compatibility with RADIUS
   [RADIUSExt], the encoding of the Data field SHOULD also conform to
   the rules for the UTF8String Data Format.

6.11.5.  Framed-Interface-Id AVP

   The Framed-Interface-Id AVP (AVP Code 96) is of type Unsigned64 and
   contains the IPv6 interface identifier to be configured for the user.
   It MAY be used in authorization requests as a hint to the server that
   a specific interface id is desired, but the server is not required to
   honor the hint in the corresponding response.



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6.11.6.  Framed-IPv6-Prefix AVP

   The Framed-IPv6-Prefix AVP (AVP Code 97) is of type OctetString and
   contains the IPv6 prefix to be configured for the user.  One or more
   AVPs MAY be used in authorization requests as a hint to the server
   that specific IPv6 prefixes are desired, but the server is not
   required to honor the hint in the corresponding response.

6.11.7.  Framed-IPv6-Route AVP

   The Framed-IPv6-Route AVP (AVP Code 99) is of type UTF8String and
   contains the ASCII routing information to be configured for the user
   on the NAS.  Zero or more of these AVPs MAY be present in an
   authorization response.

   The string MUST contain an IPv6 address prefix followed by a slash
   and a decimal length specifier stating how many high order bits of
   the prefix should be used.  This is followed by a space, a gateway
   address in hexadecimal notation, a space, and one or more metrics
   separated by spaces; for example,

      "2000:0:0:106::/64 2000::106:a00:20ff:fe99:a998 1".

   Whenever the gateway address is the IPv6 unspecified address, the IP
   address of the user SHOULD be used as the gateway address, such as
   in:

      "2000:0:0:106::/64 :: 1".

6.11.8.  Framed-IPv6-Pool AVP

   The Framed-IPv6-Pool AVP (AVP Code 100) is of type OctetString and
   contains the name of an assigned pool that SHOULD be used to assign
   an IPv6 prefix for the user.  If the access device does not support
   multiple prefix pools, it MUST ignore this AVP.

   Although specified as type OctetString for compatibility with RADIUS
   [RADIUSIPv6], the encoding of the Data field SHOULD also conform to
   the rules for the UTF8String Data Format.

6.12.  IPX Access

   The AVPs defined in this section are used when the user requests, or
   is being granted, access to an IPX network service.







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6.12.1.  Framed-IPX-Network AVP

   The Framed-IPX-Network AVP (AVP Code 23) is of type Unsigned32 and
   contains the IPX Network number to be configured for the user.  It
   MAY be used in an authorization request as a hint to the server that
   a specific address is desired, but the server is not required to
   honor the hint in the corresponding response.

   Two addresses have special significance: 0xFFFFFFFF and 0xFFFFFFFE.
   The value 0xFFFFFFFF indicates that the NAS should allow the user to
   select an address (i.e., Negotiated).  The value 0xFFFFFFFE indicates
   that the NAS should select an address for the user (e.g., assign it
   from a pool of one or more IPX networks kept by the NAS).

6.13.  AppleTalk Network Access

   The AVPs defined in this section are used when the user requests, or
   is being granted, access to an AppleTalk network [AppleTalk].

6.13.1.  Framed-AppleTalk-Link AVP

   The Framed-AppleTalk-Link AVP (AVP Code 37) is of type Unsigned32 and
   contains the AppleTalk network number that should be used for the
   serial link to the user, which is another AppleTalk router.  This AVP
   MUST only be present in an authorization response and is never used
   when the user is not another router.

   Despite the size of the field, values range from 0 to 65,535.  The
   special value of 0 indicates an unnumbered serial link.  A value of 1
   to 65,535 means that the serial line between the NAS and the user
   should be assigned that value as an AppleTalk network number.

6.13.2.  Framed-AppleTalk-Network AVP

   The Framed-AppleTalk-Network AVP (AVP Code 38) is of type Unsigned32
   and contains the AppleTalk Network number that the NAS should probe
   to allocate an AppleTalk node for the user.  This AVP MUST only be
   present in an authorization response and is never used when the user
   is not another router.  Multiple instances of this AVP indicate that
   the NAS may probe, using any of the network numbers specified.

   Despite the size of the field, values range from 0 to 65,535.  The
   special value 0 indicates that the NAS should assign a network for
   the user, using its default cable range.  A value between 1 and
   65,535 (inclusive) indicates to the AppleTalk Network that the NAS
   should probe to find an address for the user.





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6.13.3.  Framed-AppleTalk-Zone AVP

   The Framed-AppleTalk-Zone AVP (AVP Code 39) is of type OctetString
   and contains the AppleTalk Default Zone to be used for this user.
   This AVP MUST only be present in an authorization response.  Multiple
   instances of this AVP in the same message are not allowed.

   The codification of this field's allowed range is outside the scope
   of this specification.

6.14.  AppleTalk Remote Access

   The AVPs defined in this section are used when the user requests, or
   is being granted, access to the AppleTalk network via the AppleTalk
   Remote Access Protocol [ARAP].  They are only present if the Framed-
   Protocol AVP (see section 6.10.1) is set to ARAP.  Section 2.2 of RFC
   2869 [RADIUSExt] describes the operational use of these attributes.

6.14.1.  ARAP-Features AVP

   The ARAP-Features AVP (AVP Code 71) is of type OctetString and MAY be
   present in the AA-Accept message if the Framed-Protocol AVP is set to
   the value of ARAP.  See [RADIUSExt] for more information about the
   format of this AVP.

6.14.2.  ARAP-Zone-Access AVP

   The ARAP-Zone-Access AVP (AVP Code 72) is of type Enumerated and MAY
   be present in the AA-Accept message if the Framed-Protocol AVP is set
   to the value of ARAP.

   The supported values are listed in [RADIUSTypes] and defined in
   [RADIUSExt].

6.15.  Non-Framed Access Authorization AVPs

   This section contains the authorization AVPs that are needed to
   support terminal server functionality.  AVPs defined in this section
   MAY be present in a message if the Service-Type AVP was set to
   "Login" or "Callback Login".

6.15.1.  Login-IP-Host AVP

   The Login-IP-Host AVP (AVP Code 14) [RADIUS] is of type OctetString
   and contains the IPv4 address of a host with which to connect the
   user when the Login-Service AVP is included.  It MAY be used in an
   AA-Request command as a hint to the Diameter Server that a specific




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   host is desired, but the Diameter Server is not required to honor the
   hint in the AA-Answer.

   Two addresses have special significance: all ones and 0.  The value
   of all ones indicates that the NAS SHOULD allow the user to select an
   address.  The value 0 indicates that the NAS SHOULD select a host to
   connect the user to.

6.15.2.  Login-IPv6-Host AVP

   The Login-IPv6-Host AVP (AVP Code 98) [RADIUSIPv6] is of type
   OctetString and contains the IPv6 address of a host with which to
   connect the user when the Login-Service AVP is included.  It MAY be
   used in an AA-Request command as a hint to the Diameter Server that a
   specific host is desired, but the Diameter Server is not required to
   honor the hint in the AA-Answer.

   Two addresses have special significance:

   0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF and 0.  The value
   0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF indicates that the NAS SHOULD
   allow the user to select an address.  The value 0 indicates that the
   NAS SHOULD select a host to connect the user to.

6.15.3.  Login-Service AVP

   The Login-Service AVP (AVP Code 15) is of type Enumerated and
   contains the service that should be used to connect the user to the
   login host.  This AVP SHOULD only be present in authorization
   responses.

   The supported values are listed in [RADIUSTypes].  The following list
   is informational:

      0  Telnet
      1  Rlogin
      2  TCP Clear
      3  PortMaster (proprietary)
      4  LAT
      5  X25-PAD
      6  X25-T3POS
      8  TCP Clear Quiet (suppresses any NAS-generated connect
                  string)








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6.16.  TCP Services

   The AVPs described in this section MAY be present if the Login-
   Service AVP is set to Telnet, Rlogin, TCP Clear, or TCP Clear Quiet.

6.16.1.  Login-TCP-Port AVP

   The Login-TCP-Port AVP (AVP Code 16) is of type Unsigned32 and
   contains the TCP port with which the user is to be connected when the
   Login-Service AVP is also present.  This AVP SHOULD only be present
   in authorization responses.  The value MUST NOT be greater than
   65,535.

6.17.  LAT Services

   The AVPs described in this section MAY be present if the Login-
   Service AVP is set to LAT [LAT].

6.17.1.  Login-LAT-Service AVP

   The Login-LAT-Service AVP (AVP Code 34) is of type OctetString and
   contains the system with which the user is to be connected by LAT.
   It MAY be used in an authorization request as a hint to the server
   that a specific service is desired, but the server is not required to
   honor the hint in the corresponding response.  This AVP MUST only be
   present in the response if the Login-Service AVP states that LAT is
   desired.

   Administrators use this service attribute when dealing with clustered
   systems, such as a VAX or Alpha cluster.  In these environments,
   several different time-sharing hosts share the same resources (disks,
   printers, etc.), and administrators often configure each host to
   offer access (service) to each of the shared resources.  In this
   case, each host in the cluster advertises its services through LAT
   broadcasts.

   Sophisticated users often know which service providers (machines) are
   faster and tend to use a node name when initiating a LAT connection.
   Some administrators want particular users to use certain machines as
   a primitive form of load balancing (although LAT knows how to do load
   balancing itself).

   The String field contains the identity of the LAT service to use.
   The LAT Architecture allows this string to contain $ (dollar), -
   (hyphen), . (period), _ (underscore), numerics, upper- and lowercase
   alphabetics, and the ISO Latin-1 character set extension [ISOLatin].
   All LAT string comparisons are case insensitive.




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6.17.2.  Login-LAT-Node AVP

   The Login-LAT-Node AVP (AVP Code 35) is of type OctetString and
   contains the Node with which the user is to be automatically
   connected by LAT.  It MAY be used in an authorization request as a
   hint to the server that a specific LAT node is desired, but the
   server is not required to honor the hint in the corresponding
   response.  This AVP MUST only be present in a response if the Login-
   Service-Type AVP is set to LAT.

   The String field contains the identity of the LAT service to use.
   The LAT Architecture allows this string to contain $ (dollar), -
   (hyphen), . (period), _ (underscore), numerics, upper- and lowercase
   alphabetics, and the ISO Latin-1 character set extension [ISOLatin].
   All LAT string comparisons are case insensitive.

6.17.3.  Login-LAT-Group AVP

   The Login-LAT-Group AVP (AVP Code 36) is of type OctetString and
   contains a string identifying the LAT group codes this user is
   authorized to use.  It MAY be used in an authorization request as a
   hint to the server that a specific group is desired, but the server
   is not required to honor the hint in the corresponding response.
   This AVP MUST only be present in a response if the Login-Service-Type
   AVP is set to LAT.

   LAT supports 256 different group codes, which LAT uses as a form of
   access rights.  LAT encodes the group codes as a 256-bit bitmap.

   Administrators can assign one or more of the group code bits at the
   LAT service provider; it will only accept LAT connections that have
   these group codes set in the bitmap.  The administrators assign a
   bitmap of authorized group codes to each user.  LAT gets these from
   the operating system and uses them in its requests to the service
   providers.

   The codification of the range of allowed usage of this field is
   outside the scope of this specification.

6.17.4.  Login-LAT-Port AVP

   The Login-LAT-Port AVP (AVP Code 63) is of type OctetString and
   contains the Port with which the user is to be connected by LAT.  It
   MAY be used in an authorization request as a hint to the server that
   a specific port is desired, but the server is not required to honor
   the hint in the corresponding response.  This AVP MUST only be
   present in a response if the Login-Service-Type AVP is set to LAT.




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   The String field contains the identity of the LAT service to use.
   The LAT Architecture allows this string to contain $ (dollar), -
   (hyphen), . (period), _ (underscore), numerics, upper- and lower-case
   alphabetics, and the ISO Latin-1 character set extension [ISOLatin].
   All LAT string comparisons are case insensitive.

7.  NAS Tunneling

   Some NASes support compulsory tunnel services in which the incoming
   connection data is conveyed by an encapsulation method to a gateway
   elsewhere in the network.  This is typically transparent to the
   service user, and the tunnel characteristics may be described by the
   remote AAA server, based on the user's authorization information.
   Several tunnel characteristics may be returned, and the NAS
   implementation may choose one [RADTunnels], [RADTunlAcct].

                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|    |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT| NOT |Encr|
   -----------------------------------------|----+-----+----+-----|----|
   Tunneling        401   7.1    Grouped    | M  |  P  |    |  V  | N  |
   Tunnel-Type       64   7.2    Enumerated | M  |  P  |    |  V  | Y  |
   Tunnel-Medium-    65   7.3    Enumerated | M  |  P  |    |  V  | Y  |
     Type                                   |    |     |    |     |    |
   Tunnel-Client-    66   7.4    UTF8String | M  |  P  |    |  V  | Y  |
     Endpoint                               |    |     |    |     |    |
   Tunnel-Server-    67   7.5    UTF8String | M  |  P  |    |  V  | Y  |
     Endpoint                               |    |     |    |     |    |
   Tunnel-Password   69   7.6    OctetString| M  |  P  |    |  V  | Y  |
   Tunnel-Private-   81   7.7    OctetString| M  |  P  |    |  V  | Y  |
     Group-Id                               |    |     |    |     |    |
   Tunnel-           82   7.8    OctetString| M  |  P  |    |  V  | Y  |
     Assignment-Id                          |    |     |    |     |    |
   Tunnel-Preference 83   7.9    Unsigned32 | M  |  P  |    |  V  | Y  |
   Tunnel-Client-    90   7.10   UTF8String | M  |  P  |    |  V  | Y  |
     Auth-Id                                |    |     |    |     |    |
   Tunnel-Server-    91   7.11   UTF8String | M  |  P  |    |  V  | Y  |
     Auth-Id                                |    |     |    |     |    |
   -----------------------------------------|----+-----+----+-----|----|

7.1.  Tunneling AVP

   The Tunneling AVP (AVP Code 401) is of type Grouped and contains the
   following AVPs, used to describe a compulsory tunnel service:
   [RADTunnels], [RADTunlAcct].  Its data field has the following ABNF
   grammar:



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      Tunneling     ::= < AVP Header: 401 >
                        { Tunnel-Type }
                        { Tunnel-Medium-Type }
                        { Tunnel-Client-Endpoint }
                        { Tunnel-Server-Endpoint }
                        [ Tunnel-Preference ]
                        [ Tunnel-Client-Auth-Id ]
                        [ Tunnel-Server-Auth-Id ]
                        [ Tunnel-Assignment-Id ]
                        [ Tunnel-Password ]
                        [ Tunnel-Private-Group-Id ]

7.2.  Tunnel-Type AVP

   The Tunnel-Type AVP (AVP Code 64) is of type Enumerated and contains
   the tunneling protocol(s) to be used (in the case of a tunnel
   initiator) or in use (in the case of a tunnel terminator).  It MAY be
   used in an authorization request as a hint to the server that a
   specific tunnel type is desired, but the server is not required to
   honor the hint in the corresponding response.

   The Tunnel-Type AVP SHOULD also be included in Accounting-Request
   messages.

   A tunnel initiator is not required to implement any of these tunnel
   types.  If a tunnel initiator receives a response that contains only
   unknown or unsupported Tunnel-Types, the tunnel initiator MUST behave
   as though a response were received with the Result-Code indicating a
   failure.

   The supported values are listed in [RADIUSTypes].  The following list
   is informational:

       1  Point-to-Point Tunneling Protocol (PPTP)
       2  Layer Two Forwarding (L2F)
       3  Layer Two Tunneling Protocol (L2TP)
       4  Ascend Tunnel Management Protocol (ATMP)
       5  Virtual Tunneling Protocol (VTP)
       6  IP Authentication Header in the Tunnel-mode (AH)
       7  IP-in-IP Encapsulation (IP-IP)
       8  Minimal IP-in-IP Encapsulation (MIN-IP-IP)
       9  IP Encapsulating Security Payload in the Tunnel-mode (ESP)
      10  Generic Route Encapsulation (GRE)
      11  Bay Dial Virtual Services (DVS)
      12  IP-in-IP Tunneling
      13  Virtual LANs (VLAN)





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7.3.  Tunnel-Medium-Type AVP

   The Tunnel-Medium-Type AVP (AVP Code 65) is of type Enumerated and
   contains the transport medium to use when creating a tunnel for
   protocols (such as L2TP) that can operate over multiple transports.
   It MAY be used in an authorization request as a hint to the server
   that a specific medium is desired, but the server is not required to
   honor the hint in the corresponding response.

   The supported values are listed in [RADIUSTypes].  The following list
   is informational:

       1  IPv4 (IP version 4)
       2  IPv6 (IP version 6)
       3  NSAP
       4  HDLC (8-bit multidrop)
       5  BBN 1822
       6  802 (includes all 802 media plus Ethernet "canonical
                    format")
       7  E.163 (POTS)
       8  E.164 (SMDS, Frame Relay, ATM)
       9  F.69 (Telex)
      10  X.121 (X.25, Frame Relay)
      11  IPX
      12  Appletalk
      13  Decnet IV
      14  Banyan Vines
      15  E.164 with NSAP format subaddress

7.4.  Tunnel-Client-Endpoint AVP

   The Tunnel-Client-Endpoint AVP (AVP Code 66) is of type UTF8String
   and contains the address of the initiator end of the tunnel.  It MAY
   be used in an authorization request as a hint to the server that a
   specific endpoint is desired, but the server is not required to honor
   the hint in the corresponding response.

   This AVP SHOULD be included in the corresponding Accounting-Request
   messages, in which case it indicates the address from which the
   tunnel was initiated.  This AVP, along with the Tunnel-Server-
   Endpoint and Session-Id AVP [BASE], MAY be used to provide a globally
   unique means to identify a tunnel for accounting and auditing
   purposes.

   If Tunnel-Medium-Type is IPv4 (1), then this string is either the
   fully qualified domain name (FQDN) of the tunnel client machine, or a





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   "dotted-decimal" IP address.  Implementations MUST support the
   dotted-decimal format and SHOULD support the FQDN format for IP
   addresses.

   If Tunnel-Medium-Type is IPv6 (2), then this string is either the
   FQDN of the tunnel client machine, or a text representation of the
   address in either the preferred or alternate form [IPv6Addr].
   Conforming implementations MUST support the preferred form and SHOULD
   support both the alternate text form and the FQDN format for IPv6
   addresses.

   If Tunnel-Medium-Type is neither IPv4 nor IPv6, then this string is a
   tag referring to configuration data local to the Diameter client that
   describes the interface or medium-specific client address to use.

7.5.  Tunnel-Server-Endpoint AVP

   The Tunnel-Server-Endpoint AVP (AVP Code 67) is of type UTF8String
   and contains the address of the server end of the tunnel.  It MAY be
   used in an authorization request as a hint to the server that a
   specific endpoint is desired, but the server is not required to honor
   the hint in the corresponding response.

   This AVP SHOULD be included in the corresponding Accounting-Request
   messages, in which case it indicates the address from which the
   tunnel was initiated.  This AVP, along with the Tunnel-Client-
   Endpoint and Session-Id AVP [BASE], MAY be used to provide a globally
   unique means to identify a tunnel for accounting and auditing
   purposes.

   If Tunnel-Medium-Type is IPv4 (1), then this string is either the
   fully qualified domain name (FQDN) of the tunnel server machine, or a
   "dotted-decimal" IP address.  Implementations MUST support the
   dotted-decimal format and SHOULD support the FQDN format for IP
   addresses.

   If Tunnel-Medium-Type is IPv6 (2), then this string is either the
   FQDN of the tunnel server machine, or a text representation of the
   address in either the preferred or alternate form [IPv6Addr].
   Implementations MUST support the preferred form and SHOULD support
   both the alternate text form and the FQDN format for IPv6 addresses.

   If Tunnel-Medium-Type is not IPv4 or IPv6, this string is a tag
   referring to configuration data local to the Diameter client that
   describes the interface or medium-specific server address to use.






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7.6.  Tunnel-Password AVP

   The Tunnel-Password AVP (AVP Code 69) is of type OctetString and may
   contain a password to be used to authenticate to a remote server.
   The Tunnel-Password AVP contains sensitive information.  This value
   is not protected in the same manner as RADIUS [RADTunnels].

   As required in [BASE], Diameter messages are encrypted by using IPsec
   or TLS.  The Tunnel-Password AVP SHOULD NOT be used in untrusted
   proxy environments without encrypting it by using end-to-end security
   techniques, such as CMS Security [DiamCMS].

7.7.  Tunnel-Private-Group-Id AVP

   The Tunnel-Private-Group-Id AVP (AVP Code 81) is of type OctetString
   and contains the group Id for a particular tunneled session.  The
   Tunnel-Private-Group-Id AVP MAY be included in an authorization
   request if the tunnel initiator can predetermine the group resulting
   from a particular connection.  It SHOULD be included in the
   authorization response if this tunnel session is to be treated as
   belonging to a particular private group.  Private groups may be used
   to associate a tunneled session with a particular group of users.
   For example, it MAY be used to facilitate routing of unregistered IP
   addresses through a particular interface.  This AVP SHOULD be
   included in the Accounting-Request messages that pertain to the
   tunneled session.

7.8.  Tunnel-Assignment-Id AVP

   The Tunnel-Assignment-Id AVP (AVP Code 82) is of type OctetString and
   is used to indicate to the tunnel initiator the particular tunnel to
   which a session is to be assigned.  Some tunneling protocols, such as
   [PPTP] and [L2TP], allow for sessions between the same two tunnel
   endpoints to be multiplexed over the same tunnel and also for a given
   session to use its own dedicated tunnel.  This attribute provides a
   mechanism for Diameter to inform the tunnel initiator (e.g., PAC,
   LAC) whether to assign the session to a multiplexed tunnel or to a
   separate tunnel.  Furthermore, it allows for sessions sharing
   multiplexed tunnels to be assigned to different multiplexed tunnels.

   A particular tunneling implementation may assign differing
   characteristics to particular tunnels.  For example, different
   tunnels may be assigned different QoS parameters.  Such tunnels may
   be used to carry either individual or multiple sessions.  The
   Tunnel-Assignment-Id attribute thus allows the Diameter server to
   indicate that a particular session is to be assigned to a tunnel
   providing an appropriate level of service.  It is expected that any
   QoS-related Diameter tunneling attributes defined in the future



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   accompanying this one will be associated by the tunnel initiator with
   the Id given by this attribute.  In the meantime, any semantic given
   to a particular Id string is a matter left to local configuration in
   the tunnel initiator.

   The Tunnel-Assignment-Id AVP is of significance only to Diameter and
   the tunnel initiator.  The Id it specifies is only intended to be of
   local use to Diameter and the tunnel initiator.  The Id assigned by
   the tunnel initiator is not conveyed to the tunnel peer.

   This attribute MAY be included in authorization responses.  The
   tunnel initiator receiving this attribute MAY choose to ignore it and
   to assign the session to an arbitrary multiplexed or non-multiplexed
   tunnel between the desired endpoints.  This AVP SHOULD also be
   included in the Accounting-Request messages pertaining to the
   tunneled session.

   If a tunnel initiator supports the Tunnel-Assignment-Id AVP, then it
   should assign a session to a tunnel in the following manner:

      -  If this AVP is present and a tunnel exists between the
         specified endpoints with the specified Id, then the session
         should be assigned to that tunnel.

      -  If this AVP is present and no tunnel exists between the
         specified endpoints with the specified Id, then a new tunnel
         should be established for the session and the specified Id
         should be associated with the new tunnel.

      -  If this AVP is not present, then the session is assigned to an
         unnamed tunnel.  If an unnamed tunnel does not yet exist
         between the specified endpoints, then it is established and
         used for this session and for subsequent ones established
         without the Tunnel-Assignment-Id attribute.  A tunnel initiator
         MUST NOT assign a session for which a Tunnel-Assignment-Id AVP
         was not specified to a named tunnel (i.e., one that was
         initiated by a session specifying this AVP).

   Note that the same Id may be used to name different tunnels if these
   tunnels are between different endpoints.

7.9.  Tunnel-Preference AVP

   The Tunnel-Preference AVP (AVP Code 83) is of type Unsigned32 and is
   used to identify the relative preference assigned to each tunnel when
   more than one set of tunneling AVPs is returned within separate
   Grouped-AVP AVPs.  It MAY be used in an authorization request as a
   hint to the server that a specific preference is desired, but the



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   server is not required to honor the hint in the corresponding
   response.

   For example, suppose that AVPs describing two tunnels are returned by
   the server, one with a Tunnel-Type of PPTP and the other with a
   Tunnel-Type of L2TP.  If the tunnel initiator supports only one of
   the Tunnel-Types returned, it will initiate a tunnel of that type.
   If, however, it supports both tunnel protocols, it SHOULD use the
   value of the Tunnel-Preference AVP to decide which tunnel should be
   started.  The tunnel with the lowest numerical value in the Value
   field of this AVP SHOULD be given the highest preference.  The values
   assigned to two or more instances of the Tunnel-Preference AVP within
   a given authorization response MAY be identical.  In this case, the
   tunnel initiator SHOULD use locally configured metrics to decide
   which set of AVPs to use.

7.10.  Tunnel-Client-Auth-Id AVP

   The Tunnel-Client-Auth-Id AVP (AVP Code 90) is of type UTF8String and
   specifies the name used by the tunnel initiator during the
   authentication phase of tunnel establishment.  It MAY be used in an
   authorization request as a hint to the server that a specific
   preference is desired, but the server is not required to honor the
   hint in the corresponding response.  This AVP MUST be present in the
   authorization response if an authentication name other than the
   default is desired.  This AVP SHOULD be included in the Accounting-
   Request messages pertaining to the tunneled session.

7.11.  Tunnel-Server-Auth-Id AVP

   The Tunnel-Server-Auth-Id AVP (AVP Code 91) is of type UTF8String and
   specifies the name used by the tunnel terminator during the
   authentication phase of tunnel establishment.  It MAY be used in an
   authorization request as a hint to the server that a specific
   preference is desired, but the server is not required to honor the
   hint in the corresponding response.  This AVP MUST be present in the
   authorization response if an authentication name other than the
   default is desired.  This AVP SHOULD be included in the Accounting-
   Request messages pertaining to the tunneled session.

8.  NAS Accounting

   Applications implementing this specification use Diameter Accounting,
   as defined in [BASE], and the AVPs in the following section.
   Service-specific AVP usage is defined in the tables in section 10.

   If accounting is active, Accounting Request (ACR) messages SHOULD be
   sent after the completion of any Authentication or Authorization



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   transaction and at the end of a Session.  The Accounting-Record-Type
   value indicates the type of event.  All other AVPs identify the
   session and provide additional information relevant to the event.

   The successful completion of the first Authentication or
   Authorization transaction SHOULD cause a START_RECORD to be sent.  If
   additional Authentications or Authorizations occur in later
   transactions, the first exchange should generate a START_RECORD, and
   the later an INTERIM_RECORD.  For a given session, there MUST only be
   one set of matching START and STOP records, with any number of
   INTERIM_RECORDS in between, or one EVENT_RECORD indicating the reason
   a session wasn't started.

   The following table describes the AVPs; their AVP Code values, types,
   and possible flag values; and whether the AVP MAY be encrypted.

                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|    |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
   -----------------------------------------|----+-----+----+-----|----|
   Accounting-      363  8.1     Unsigned64 | M  |  P  |    |  V  | Y  |
     Input-Octets                           |    |     |    |     |    |
   Accounting-      364  8.2     Unsigned64 | M  |  P  |    |  V  | Y  |
     Output-Octets                          |    |     |    |     |    |
   Accounting-      365  8.3     Unsigned64 | M  |  P  |    |  V  | Y  |
     Input-Packets                          |    |     |    |     |    |
   Accounting-      366  8.4     Unsigned64 | M  |  P  |    |  V  | Y  |
     Output-Packets                         |    |     |    |     |    |
   Acct-Session-Time 46  8.5     Unsigned32 | M  |  P  |    |  V  | Y  |
   Acct-Authentic    45  8.6     Enumerated | M  |  P  |    |  V  | Y  |
   Acounting-Auth-  406  8.7     Enumerated | M  |  P  |    |  V  | Y  |
     Method                                 |    |     |    |     |    |
   Acct-Delay-Time   41  8.8     Unsigned32 | M  |  P  |    |  V  | Y  |
   Acct-Link-Count   51  8.9     Unsigned32 | M  |  P  |    |  V  | Y  |
   Acct-Tunnel-      68  8.10    OctetString| M  |  P  |    |  V  | Y  |
     Connection                             |    |     |    |     |    |
   Acct-Tunnel-      86  8.11    Unsigned32 | M  |  P  |    |  V  | Y  |
     Packets-Lost                           |    |     |    |     |    |
   -----------------------------------------|----+-----+----+-----|----|

8.1.  Accounting-Input-Octets AVP

   The Accounting-Input-Octets AVP (AVP Code 363) is of type Unsigned64
   and contains the number of octets received from the user.





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   For NAS usage, this AVP indicates how many octets have been received
   from the port in the course of this session.  It can only be present
   in ACR messages with an Accounting-Record-Type of INTERIM_RECORD or
   STOP_RECORD.

8.2.  Accounting-Output-Octets AVP

   The Accounting-Output-Octets AVP (AVP Code 364) is of type Unsigned64
   and contains the number of octets sent to the user.

   For NAS usage, this AVP indicates how many octets have been sent to
   the port in the course of this session.  It can only be present in
   ACR messages with an Accounting-Record-Type of INTERIM_RECORD or
   STOP_RECORD.

8.3.  Accounting-Input-Packets AVP

   The Accounting-Input-Packets (AVP Code 365) is of type Unsigned64 and
   contains the number of packets received from the user.

   For NAS usage, this AVP indicates how many packets have been received
   from the port over the course of a session being provided to a Framed
   User.  It can only be present in ACR messages with an Accounting-
   Record-Type of INTERIM_RECORD or STOP_RECORD.

8.4.  Accounting-Output-Packets AVP

   The Accounting-Output-Packets (AVP Code 366) is of type Unsigned64
   and contains the number of IP packets sent to the user.

   For NAS usage, this AVP indicates how many packets have been sent to
   the port over the course of a session being provided to a Framed
   User.  It can only be present in ACR messages with an Accounting-
   Record-Type of INTERIM_RECORD or STOP_RECORD.

8.5.  Acct-Session-Time AVP

   The Acct-Session-Time AVP (AVP Code 46) is of type Unsigned32 and
   indicates the length of the current session in seconds.  It can only
   be present in ACR messages with an Accounting-Record-Type of
   INTERIM_RECORD or STOP_RECORD.

8.6.  Acct-Authentic AVP

   The Acct-Authentic AVP (AVP Code 45) is of type Enumerated and
   specifies how the user was authenticated.  The supported values are
   listed in [RADIUSTypes].  The following list is informational:




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      1  RADIUS
      2  Local
      3  Remote
      4  Diameter

8.7.  Accounting-Auth-Method AVP

   The Accounting-Auth-Method AVP (AVP Code 406) is of type Enumerated.
   A NAS MAY include this AVP in an Accounting-Request message to
   indicate the method used to authenticate the user.  (Note that this
   is equivalent to the RADIUS MS-Acct-Auth-Type VSA attribute).

   The following values are defined:

      1  PAP
      2  CHAP
      3  MS-CHAP-1
      4  MS-CHAP-2
      5  EAP
      7  None

8.8.  Acct-Delay-Time

   The Acct-Delay-Time AVP (AVP Code 41) is of type Unsigned32 and
   indicates the number of seconds the Diameter client has been trying
   to send the Accounting-Request (ACR).  The accounting server may
   subtract this value from the time when the ACR arrives at the server
   to calculate the approximate time of the event that caused the ACR to
   be generated.

   This AVP is not used for retransmissions at the transport level (TCP
   or SCTP).  Rather, it may be used when an ACR command cannot be
   transmitted because there is no appropriate peer to transmit it to or
   was rejected because it could not be delivered.  In these cases, the
   command MAY be buffered and transmitted later, when an appropriate
   peer-connection is available or after sufficient time has passed that
   the destination-host may be reachable and operational.  If the ACR is
   resent in this way, the Acct-Delay-Time AVP SHOULD be included.  The
   value of this AVP indicates the number of seconds that elapsed
   between the time of the first attempt at transmission and the current
   attempt.










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8.9.  Acct-Link-Count

   The Acct-Link-Count AVP (AVP Code 51) is of type Unsigned32 and
   indicates the total number of links that have been active (current or
   closed) in a given multilink session at the time the accounting
   record is generated.  This AVP MAY be included in Accounting-Requests
   for any session that may be part of a multilink service.

   The Acct-Link-Count AVP may be used to make it easier for an
   accounting server to know when it has all the records for a given
   multilink service.  When the number of Accounting-Requests received
   with Accounting-Record-Type = STOP_RECORD and with the same Acct-
   Multi-Session-Id and unique Session-Ids equals the largest value of
   Acct-Link-Count seen in those Accounting-Requests, all STOP_RECORD
   Accounting-Requests for that multilink service have been received.

   The following example, showing eight Accounting-Requests, illustrates
   how the Acct-Link-Count AVP is used.  In the table below, only the
   relevant AVPs are shown, although additional AVPs containing
   accounting information will be present in the Accounting-Requests.

      Acct-Multi-                   Accounting-     Acct-
      Session-Id     Session-Id     Record-Type     Link-Count
      --------------------------------------------------------
        "...10"        "...10"      START_RECORD        1
        "...10"        "...11"      START_RECORD        2
        "...10"        "...11"      STOP_RECORD         2
        "...10"        "...12"      START_RECORD        3
        "...10"        "...13"      START_RECORD        4
        "...10"        "...12"      STOP_RECORD         4
        "...10"        "...13"      STOP_RECORD         4
        "...10"        "...10"      STOP_RECORD         4

8.10.  Acct-Tunnel-Connection AVP

   The Acct-Tunnel-Connection AVP (AVP Code 68) is of type OctetString
   and contains the identifier assigned to the tunnel session.  This
   AVP, along with the Tunnel-Client-Endpoint and Tunnel-Server-Endpoint
   AVPs, may be used to provide a means to uniquely identify a tunnel
   session for auditing purposes.

   The format of the identifier in this AVP depends upon the value of
   the Tunnel-Type AVP.  For example, to identify an L2TP tunnel
   connection fully, the L2TP Tunnel Id and Call Id might be encoded in
   this field.  The exact encoding of this field is implementation
   dependent.





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8.11.  Acct-Tunnel-Packets-Lost AVP

   The Acct-Tunnel-Packets-Lost AVP (AVP Code 86) is of type Unsigned32
   and contains the number of packets lost on a given link.

9.  RADIUS/Diameter Protocol Interactions

   This section describes some basic guidelines that servers acting as
   AAA Translation Agents may use.  A complete description of all the
   differences between RADIUS and Diameter is beyond the scope of this
   section and document.  Note that this document does not restrict
   implementations from creating additional translation methods, as long
   as the translation function doesn't violate the RADIUS or the
   Diameter protocols.

   Although the Diameter protocol is in many ways a superset of RADIUS
   functions, a number of RADIUS representations are not allowed, so
   that new capabilities can be used without the old problems.

   There are primarily two different situations that must be handled:
   one in which a RADIUS request is received that must be forwarded as a
   Diameter request, and another in which the inverse is true.  RADIUS
   does not support a peer-to-peer architecture, and server-initiated
   operations are generally not supported.  See [RADDynAuth] for an
   alternative.

   Some RADIUS attributes are encrypted.  RADIUS security and encryption
   techniques are applied on a hop-per-hop basis.  A Diameter agent will
   have to decrypt RADIUS attribute data entering the Diameter system,
   and if that information is forwarded, the agent MUST secure it by
   using Diameter specific techniques.

   Note that this section uses the two terms, "AVP" and "attribute", in
   a concise and specific manner.  The former is used to signify a
   Diameter AVP, and the latter to signify a RADIUS attribute.

9.1.  RADIUS Request Forwarded as Diameter Request

   This section describes the actions that should be taken when a
   Translation Agent receives a RADIUS message to be translated to a
   Diameter message.

   Note that RADIUS servers are assumed to be stateless.  It is also
   quite possible for the RADIUS messages that comprise the session
   (i.e., authentication and accounting messages) to be handled by
   different Translation Agents in the proxy network.  Therefore, a
   RADIUS/Diameter Translation Agent SHOULD NOT be assumed to have an
   accurate track on session-state information.



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   When a Translation Agent receives a RADIUS message, the following
   steps should be taken:

      -  If a Message-Authenticator attribute is present, the value MUST
         be checked but not included in the Diameter message.  If it is
         incorrect, the RADIUS message should be silently discarded.
         The gateway system SHOULD generate and include a Message-
         Authenticator in returned RADIUS responses.

      -  The transport address of the sender MUST be checked against the
         NAS identifying attributes.  See the description of NAS-
         Identifier and NAS-IP-Address below.

      -  The Translation Agent must maintain transaction state
         information relevant to the RADIUS request, such as the
         Identifier field in the RADIUS header, any existing RADIUS
         Proxy-State attribute, and the source IP address and port
         number of the UDP packet.  These may be maintained locally in a
         state table or saved in a Proxy-Info AVP group.  A Diameter
         Session-Id AVP value must be created using a session state
         mapping mechanism.

      -  If the RADIUS request contained a State attribute and the
         prefix of the data is "Diameter/", the data following the
         prefix contains the Diameter Origin-Host/Origin-Realm/Session-
         Id.  If no such attributes are present and the RADIUS command
         is an Access-Request, a new Session-Id is created.  The
         Session-Id is included in the Session-Id AVP.

      -  The Diameter Origin-Host and Origin-Realm AVPs MUST be created
         and added by using the information from an FQDN corresponding
         to the NAS-IP-Address attribute (preferred if available),
         and/or to the NAS-Identifier attribute.  (Note that the RADIUS
         NAS-Identifier is not required to be an FQDN.)

      -  The response MUST have an Origin-AAA-Protocol AVP added,
         indicating the protocol of origin of the message.

      -  The Proxy-Info group SHOULD be added, with the local server's
         identity specified in the Proxy-Host AVP.  This should ensure
         that the response is returned to this system.

      -  The Destination-Realm AVP is created from the information found
         in the RADIUS User-Name attribute.







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      -  If the RADIUS User-Password attribute is present, the password
         must be unencrypted by using the link's RADIUS shared secret.
         The unencrypted value must be forwarded in a User-Password AVP
         using Diameter security.

      -  If the RADIUS CHAP-Password attribute is present, the Ident and
         Data portion of the attribute are used to create the CHAP-Auth
         grouped AVP.

      -  If the RADIUS message contains an address attribute, it MUST be
         converted to the appropriate Diameter AVP and type.

      -  If the RADIUS message contains Tunnel information [RADTunnels],
         the attributes or tagged groups should each be converted to a
         Diameter Tunneling Grouped AVP set.  If the tunnel information
         contains a Tunnel-Password attribute, the RADIUS encryption
         must be resolved, and the password forwarded, by using Diameter
         security methods.

      -  If the RADIUS message received is an Accounting-Request, the
         Acct-Status-Type attribute value must be converted to a
         Accounting-Record-Type AVP value.  If the Acct-Status-Type
         attribute value is STOP, the local server MUST issue a
         Session-Termination-Request message once the Diameter
         Accounting-Answer message has been received.

      -  If the Accounting message contains an Acct-Termination-Cause
         attribute, it should be translated to the equivalent
         Termination-Cause AVP value.  (see below)

      -  If the RADIUS message contains the Accounting-Input-Octets,
         Accounting-Input-Packets, Accounting-Output-Octets, or
         Accounting-Output-Packets, these attributes must be converted
         to the Diameter equivalents.  Further, if the Acct-Input-
         Gigawords or Acct-Output-Gigawords attributes are present,
         these must be used to properly compute the Diameter accounting
         AVPs.

   The corresponding Diameter response is always guaranteed to be
   received by the same Translation Agent that translated the original
   request, due to the contents of the Proxy-Info AVP group in the
   Diameter request.  The following steps are applied to the response
   message during the Diameter-to-RADIUS translation:

      -  If the Diameter Command-Code is set to AA-Answer and the
         Result-Code AVP is set to DIAMETER_MULTI_ROUND_AUTH, the
         gateway must send a RADIUS Access-Challenge.  This must have
         the Origin-Host, Origin-Realm, and Diameter Session-Id AVPs



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         encapsulated in the RADIUS State attribute, with the prefix
         "Diameter/", concatenated in the above order separated with "/"
         characters, in UTF-8 [UTF-8].  This is necessary to ensure that
         the Translation Agent receiving the subsequent RADIUS Access-
         Request will have access to the Session Identifier and be able
         to set the Destination-Host to the correct value.  If the
         Multi-Round-Time-Out AVP is present, the value of the AVP MUST
         be inserted in the RADIUS Session-Timeout AVP.

      -  If the Command-Code is set to AA-Answer, the Diameter Session-
         Id AVP is saved in a new RADIUS Class attribute whose format
         consists of the string "Diameter/" followed by the Diameter
         Session Identifier.  This will ensure that the subsequent
         Accounting messages, which could be received by any Translation
         Agent, would have access to the original Diameter Session
         Identifier.
      -  If a Proxy-State attribute was present in the RADIUS request,
         the same attribute is added in the response.  This information
         may be found in the Proxy-Info AVP group, or in a local state
         table.

      -  If state information regarding the RADIUS request was saved in
         a Proxy-Info AVP or local state table, the RADIUS Identifier
         and UDP IP Address and port number are extracted and used in
         issuing the RADIUS reply.

   When translating a Diameter AA-Answer (with successful result code)
   to RADIUS Access-Accept that contains a Session-Timeout or
   Authorization-Lifetime AVP, take the following steps:

      -  If the Diameter message contains a Session-Timeout AVP but no
         Authorization-Lifetime AVP, translate it to a Session-Timeout
         attribute (not a Termination-Action).

      -  If the Diameter message contains an Authorization-Lifetime AVP
         but no Session-Timeout AVP, translate it to a Session-Timeout
         attribute and a Termination-Action set to AA-REQUEST.  (Remove
         Authorization-Lifetime and Re-Auth-Request-Type.)

      -  If the Diameter message has both, the Session-Timeout must be
         greater than or equal to the Authorization-Lifetime (required
         by [BASE]).  Translate it to a Session-Timeout value (with
         value from Authorization-Lifetime AVP, the smaller one) and
         with the Termination-Action set to AA-REQUEST.  (Remove the
         Authorization-Lifetime and Re-Auth-Request-Type.)






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9.1.1.  RADIUS Dynamic Authorization Considerations

   A Diameter/RADIUS gateway may communicate with a server that
   implements RADIUS Dynamic Authorization [RADDynAuth].  If the server
   supports these functions, it MUST be listening on the assigned port
   and would receive RADIUS CoA-Request and Disconnect-Request messages.
   These can be mapped into the Diameter Re-Auth-Request (RAR) and
   Abort-Session-Request (ASR) message exchanges, respectively [BASE].

   If the [RADDynAuth] is not supported, the port would not be active
   and the RADIUS server would receive an ICMP Port Unreachable
   indication.  Alternatively, if the messages are received but with an
   inappropriate Service-Type, the gateway can respond with the
   appropriate NAK message and an Error-Cause attribute with the value
   of 405, "Unsupported Service".

   The RADIUS CoA-Request and Disconnect-Request messages will not
   contain a Diameter Session-Id.  Diameter requires that this value
   match an active session context.  The gateway MUST have a session Id
   cache (or other means) to identify the sessions these functions
   pertain to.  If unable to identify the session, the gateway (or NAS)
   should return an Error-Cause value 503, "Session Context Not Found".

   The RADIUS CoA-Request message only supports a change of
   authorization attributes, and the received CoA-Request SHOULD include
   a Service-Type of "Authorize-Only".  This indicates an extended
   exchange request by the rules given in [RADDynAuth] section 3.2, note
   6.  This is the only type of exchange supported by Diameter [BASE].

   For the CoA-Request, the translated RAR message will have a Re-Auth-
   Type of AUTHORIZE_ONLY.  The returned RAA will be translated into a
   CoA-NAK with Error-Cause "Request Initiated".  The gateway's Diameter
   client SHOULD also start a reauthorization sequence by sending an AAR
   message, which will be translated into an Access-Request message.
   The RADIUS server will use the Access-Accept (or Access-Reject)
   message to convey the new authorization attributes, which the gateway
   will pass back in an AAA message.

   Any attributes included in the COA-Request or Access-Accept message
   are to be considered mandatory in Diameter.  If they cannot be
   supported, they MUST result in an error message return to the RADIUS
   server, with an Error-Cause of "Unsupported Attribute".  The Diameter
   NAS will attempt to apply all the attributes supplied in the AA
   message to the session.

   A RADIUS Disconnect-Request message received by the gateway would be
   translated to a Diameter Abort-Session-Request (ASR) message [BASE].
   The results will be returned by the Diameter client in an Abort-



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   Session-Answer (ASA) message.  A success indication would translate
   to a RADIUS Disconnect-ACK, and a failure would generate a
   Disconnect-NAK.

9.2.  Diameter Request Forwarded as RADIUS Request

   When a server receives a Diameter request to be forwarded to a RADIUS
   entity, the following are examples of the steps that may be taken:

      -  The Origin-Host AVP's value is inserted into the NAS-Identifier
         attribute.

      -  The following information MUST be present in the corresponding
         Diameter response and therefore MUST be saved, either in a
         local state table or encoded in a RADIUS Proxy-State attribute:

            1. Origin-Host AVP
            2. Session-Id AVP
            3. Proxy-Info AVP
            4. Any other AVP that MUST be present in the response and
               has no corresponding RADIUS attribute.

      -  If the CHAP-Auth AVP is present, the grouped AVPs are used to
         create the RADIUS CHAP-Password attribute data.

      -  If the User-Password AVP is present, the data should be
         encrypted and forwarded by using RADIUS rules.  The same is
         true for any other RADIUS-encrypted attribute values.

      -  AVPs of the type Address must be translated to the
         corresponding RADIUS attribute.

      -  If the Accounting-Input-Octets, Accounting-Input-Packets,
         Accounting-Output-Octets, or Accounting-Output-Packets AVPs are
         present, they must be translated to the corresponding RADIUS
         attributes.  If the value of the Diameter AVPs do not fit
         within a 32-bit RADIUS attribute, the RADIUS Acct-Input-
         Gigawords and Acct-Output-Gigawords must be used.

      -  If the RADIUS link supports the Message-Authenticator attribute
         [RADIUSExt], it SHOULD be generated and added to the request.

   When the corresponding response is received by the Translation Agent,
   which is guaranteed in the RADIUS protocol, the following steps may
   be taken:






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      -  If the RADIUS code is set to Access-Challenge, a Diameter AA-
         Answer message is created with the Result-Code set to
         DIAMETER_MULTI_ROUND_AUTH.  If the Session-Timeout AVP is
         present in the RADIUS message, its value is inserted into the
         Multi-Round-Time-Out AVP.

      - If a Proxy-State attribute is present, extract the encoded
         information; otherwise, retrieve the original Proxy-Info AVP
         group information from the local state table.

      -  The response's Origin-Host information is created from the FQDN
         of the RADIUS message's source IP address.  The same FQDN is
         also stored to a Route-Record AVP.

      -  The response's Destination-Host AVP is copied from the saved
         request's Origin-Host information.

      -  The Session-Id information can be recovered from local state,
         or from the constructed State or Proxy-State attribute, as
         above.

      -  If a Proxy-Info AVP was present in the request, the same AVP
         MUST be added to the response.

      -  If the RADIUS State attributes are present, they must be
         present in the Diameter response, minus those added by the
         gateway.

      -  Any other AVPs that were saved at request time, and that MUST
         be present in the response, are added to the message.

   When translating a RADIUS Access-Accept to Diameter AA-Answer that
   contains a Session-Timeout attribute, do the following:

      -  If the RADIUS message contains a Session-Timeout attribute and
         a Termination-Action attribute set to DEFAULT (or no
         Termination-Action attribute at all), translate it to AA-Answer
         with a Session-Timeout AVP and remove the Termination-Action
         attribute.

      -  If the RADIUS message contains a Session-Timeout attribute and
         a Termination-Action attribute set to AA-REQUEST, translate it
         to AA-Answer with Authorization-Lifetime AVP and with Re-Auth-
         Request-Type set to AUTHORIZE_AUTHENTICATE and remove the
         Session-Timeout attribute.






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9.2.1.  RADIUS Dynamic Authorization Considerations

   A RADIUS/Diameter gateway communicating with a RADIUS client that
   implements RADIUS Dynamic Authorization [RADDynAuth] may translate
   Diameter Re-Auth-Request (RAR) messages and Abort-Session-Request
   (ASR) messages [BASE] into RADIUS CoA-Request and Disconnect-Request
   messages respectively.

   If the RADIUS client does not support the capability, the gateway
   will receive an ICMP Port Unreachable indication when it transmits
   the RADIUS message.  Even if the NAS supports [RADDynAuth], it may
   not support the Service-Type in the request message.  In this case it
   will respond with a NAK message and (optionally) an Error-Cause
   attribute with value 405, "Unsupported Service".  If the gateway
   encounters these error conditions, or if it does not support
   [RADDynAuth], it sends a Diameter Answer message with an Result-Code
   AVP of "DIAMETER_COMMAND_UNSUPPORTED" to the AAA server.

   When encoding the RADIUS messages, the gateway MUST include the
   Diameter Session-ID in the RADIUS State attribute value, as mentioned
   above.  The RADIUS client should return it in the response.

   A Diameter Re-Auth-Request (RAR) message [BASE] received by the
   gateway will be translated into a RADIUS CoA-Request and sent to the
   RADIUS client.  The RADIUS client should respond with a CoA-ACK or
   CoA-NAK message, which the gateway should translate into a Re-Auth-
   Answer (RAA) message.

   If the gateway receives a RADIUS CoA-NAK response containing a
   Service-Type Attribute with value "Authorize Only" and an Error-Cause
   Attribute with value "Request Initiated", this indicates an extended
   exchange request per [RADDynAuth] section 3.2, note 6.

   The response is translated to a Diameter Re-Auth-Answer (RAA) with a
   Result-Code AVP of "DIAMETER_LIMITED_SUCCESS" sent to the AAA server.

   Subsequently, the gateway should receive a RADIUS Access-Request from
   the NAS, with a Service-Type of "Authorize Only".  This is translated
   into a Diameter AA-Request with an Auth-Request-Type AVP of
   AUTHORIZE_ONLY and sent to the AAA server.  The AAA server will then
   reply with a Diameter AA-Answer, which is translated into a RADIUS
   Access-Accept or Access-Reject, depending on the value of the
   Result-Code AVP.

   A Diameter Abort-Session-Request (ASR) message [BASE] received by the
   gateway will be translated into a RADIUS Disconnect-Request and sent
   to the RADIUS client.  The RADIUS client should respond with a




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   Disconnect-ACK or Disconnect-NAK message, which the gateway should
   translate into an Abort-Session-Answer (ASA) message.

   If the gateway receives a RADIUS Disconnect-NAK response containing a
   Service-Type Attribute with value "Authorize Only" and an Error-Cause
   Attribute with value "Request Initiated", the Disconnect-NAK response
   is translated into a Diameter Abort-Session-Answer (ASA) with a
   Result-Code AVP of "DIAMETER_LIMITED_SUCCESS" sent to the AAA server.

   Subsequently, the gateway should receive a RADIUS Access-Request from
   the NAS, with a Service-Type of "Authorize Only".  This is translated
   into a Diameter AA-Request with an Auth-Request-Type AVP of
   AUTHORIZE_ONLY and sent to the AAA server.  The AAA server will then
   reply with a Diameter AA-Answer, which is translated into a RADIUS
   Access-Accept or Access-Reject, depending on the value of the
   Result-Code AVP.

9.3.  AVPs Used Only for Compatibility

   The AVPs defined in this section SHOULD only be used for backwards
   compatibility when a Diameter/RADIUS translation function is invoked
   and are not typically originated by Diameter systems during normal
   operations.

                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|    |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
   -----------------------------------------|----+-----+----+-----|----|
   NAS-Identifier    32  9.3.1   UTF8String | M  |  P  |    |  V  | Y  |
   NAS-IP-Address     4  9.3.2   OctetString| M  |  P  |    |  V  | Y  |
   NAS-IPv6-Address  95  9.3.3   OctetString| M  |  P  |    |  V  | Y  |
   State             24  9.3.4   OctetString| M  |  P  |    |  V  | Y  |
   Termination-     295  9.3.5   Enumerated | M  |  P  |    |  V  | Y  |
      Cause                                 |    |     |    |     |    |
   Origin-AAA-      408  9.3.6   Enumerated | M  |  P  |    |  V  | Y  |
      Protocol                              |    |     |    |     |    |
   -----------------------------------------|----+-----+----+-----|----|

9.3.1.  NAS-Identifier AVP

   The NAS-Identifier AVP (AVP Code 32) [RADIUS] is of type UTF8String
   and contains the identity of the NAS providing service to the user.
   This AVP SHOULD only be added by a RADIUS/Diameter Translation Agent.
   When this AVP is present, the Origin-Host AVP identifies the NAS
   providing service to the user.




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   In RADIUS it would be possible for a rogue NAS to forge the NAS-
   Identifier attribute.  Diameter/RADIUS translation agents SHOULD
   attempt to check a received NAS-Identifier attribute against the
   source address of the RADIUS packet, by doing an A/AAAA RR query.  If
   the NAS-Identifier attribute contains an FQDN, then such a query
   would resolve to an IP address matching the source address.  However,
   the NAS-Identifier attribute is not required to contain an FQDN, so
   such a query could fail.  If it fails, an error should be logged, but
   no action should be taken, other than a reverse lookup on the source
   address and insert the resulting FQDN into the Route-Record AVP.

   Diameter agents and servers SHOULD check whether a NAS-Identifier AVP
   corresponds to an entry in the Route-Record AVP.  If no match is
   found, then an error is logged, but no other action is taken.

9.3.2.  NAS-IP-Address AVP

   The NAS-IP-Address AVP (AVP Code 4) [RADIUS] is of type OctetString
   and contains the IP Address of the NAS providing service to the user.
   This AVP SHOULD only be added by a RADIUS/Diameter Translation Agent.
   When this AVP is present, the Origin-Host AVP identifies the NAS
   providing service to the user.

   In RADIUS it would be possible for a rogue NAS to forge the NAS-IP-
   Address attribute value.  Diameter/RADIUS translation agents MUST
   check a received NAS-IP-Address or NAS-IPv6-Address attribute against
   the source address of the RADIUS packet.  If they do not match and
   the Diameter/RADIUS translation agent does not know whether the
   packet was sent by a RADIUS proxy or NAS (e.g., no Proxy-State
   attribute), then by default it is assumed that the source address
   corresponds to a RADIUS proxy, and that the NAS Address is behind
   that proxy, potentially with some additional RADIUS proxies in
   between.  The Diameter/RADIUS translation agent MUST insert entries
   in the Route-Record AVP corresponding to the apparent route.  This
   implies doing a reverse lookup on the source address and NAS-IP-
   Address or NAS-IPv6-Address attributes to determine the corresponding
   FQDNs.

   If the source address and the NAS-IP-Address or NAS-IPv6-Address do
   not match, and the Diameter/RADIUS translation agent knows that it is
   talking directly to the NAS (e.g., there are no RADIUS proxies
   between it and the NAS), then the error should be logged, and the
   packet MUST be discarded.

   Diameter agents and servers MUST check whether the NAS-IP-Address AVP
   corresponds to an entry in the Route-Record AVP.  This is done by
   doing a reverse lookup (PTR RR) for the NAS-IP-Address to retrieve
   the corresponding FQDN, and by checking for a match with the Route-



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   Record AVP.  If no match is found, then an error is logged, but no
   other action is taken.

9.3.3.  NAS-IPv6-Address AVP

   The NAS-IPv6-Address AVP (AVP Code 95) [RADIUSIPv6] is of type
   OctetString and contains the IPv6 Address of the NAS providing
   service to the user.  This AVP SHOULD only be added by a
   RADIUS/Diameter Translation Agent.  When this AVP is present, the
   Origin-Host AVP identifies the NAS providing service to the user.

   In RADIUS it would be possible for a rogue NAS to forge the NAS-
   IPv6-Address attribute.  Diameter/RADIUS translation agents MUST
   check a received NAS-IPv6-Address attribute against the source
   address of the RADIUS packet.  If they do not match and the
   Diameter/RADIUS translation agent does not know whether the packet
   was sent by a RADIUS proxy or NAS (e.g., no Proxy-State attribute),
   then by default it is assumed that the source address corresponds to
   a RADIUS proxy, and that the NAS-IPv6-Address is behind that proxy,
   potentially with some additional RADIUS proxies in between.  The
   Diameter/RADIUS translation agent MUST insert entries in the Route-
   Record AVP corresponding to the apparent route.  This implies doing a
   reverse lookup on the source address and NAS-IPv6-Address attributes
   to determine the corresponding FQDNs.

   If the source address and the NAS-IPv6-Address do not match, and the
   Diameter/RADIUS translation agent knows that it is talking directly
   to the NAS (e.g., there are no RADIUS proxies between it and the
   NAS), then the error should be logged, and the packet MUST be
   discarded.

   Diameter agents and servers MUST check whether the NAS-IPv6-Address
   AVP corresponds to an entry in the Route-Record AVP.  This is done by
   doing a reverse lookup (PTR RR) for the NAS-IPv6-Address to retrieve
   the corresponding FQDN, and by checking for a match with the Record-
   Route AVP.  If no match is found, then an error is logged, but no
   other action is taken.

9.3.4.  State AVP

   The State AVP (AVP Code 24) [RADIUS] is of type OctetString and has
   two uses in the Diameter NAS application.

   The State AVP MAY be sent by a Diameter Server to a NAS in an AA-
   Response command that contains a Result-Code of
   DIAMETER_MULTI_ROUND_AUTH.  If so, the NAS MUST return it unmodified
   in the subsequent AA-Request command.




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   The State AVP MAY also be sent by a Diameter Server to a NAS in an
   AA-Response command that also includes a Termination-Action AVP with
   the value of AA-REQUEST.  If the NAS performs the Termination-Action
   by sending a new AA-Request command upon termination of the current
   service, it MUST return the State AVP unmodified in the new request
   command.

   In either usage, the NAS MUST NOT interpret the AVP locally.  Usage
   of the State AVP is implementation dependent.

9.3.5.  Termination-Cause AVP Code Values

   This section defines a mapping between Termination-Cause AVP code
   values and RADIUS Acct-Terminate-Cause attribute code values from RFC
   2866 [RADIUSAcct] and [RADIUSTypes], thereby allowing a
   RADIUS/Diameter Translation Agent to convert between the attribute
   and AVP values.  This section thus extends the definitions in the
   "Termination-Cause AVP" section of the Base Diameter specification.

































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   The table in this section defines the mapping between Termination-
   Cause AVP and RADIUS Acct-Terminate-Cause causes.

                                 +-----------------------+
                                 |         Value         |
                                 +-----------+-----------+
   Cause Value Name              |  RADIUS   | Diameter  |
   ------------------------------|-----------+-----------+
   User Request                  |     1     |   11      |
   Lost Carrier                  |     2     |   12      |
   Lost Service                  |     3     |   13      |
   Idle Timeout                  |     4     |   14      |
   Session Timeout               |     5     |   15      |
   Admin Reset                   |     6     |   16      |
   Admin Reboot                  |     7     |   17      |
   Port Error                    |     8     |   18      |
   NAS Error                     |     9     |   19      |
   NAS Request                   |     10    |   20      |
   NAS Reboot                    |     11    |   21      |
   Port Unneeded                 |     12    |   22      |
   Port Preempted                |     13    |   23      |
   Port Suspended                |     14    |   24      |
   Service Unavailable           |     15    |   25      |
   Callback                      |     16    |   26      |
   User Error                    |     17    |   27      |
   Host Request                  |     18    |   28      |
   Supplicant Restart            |     19    |   29      |  [RAD802.1X]
   Reauthentication Failure      |     20    |   30      |  [RAD802.1X]
   Port Reinit                   |     21    |   31      |  [RAD802.1X]
   Port Disabled                 |     22    |   32      |  [RAD802.1X]
   ------------------------------|-----------+-----------+

   From RFC 2866, the termination causes are as follows:

   User Request         User requested termination of service, for
                        example with LCP Terminate or by logging out.

   Lost Carrier         DCD was dropped on the port.

   Lost Service         Service can no longer be provided; for
                        example, user's connection to a host was
                        interrupted.

   Idle Timeout         Idle timer expired.

   Session Timeout      Maximum session length timer expired.

   Admin Reset          Administrator reset the port or session.



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   Admin Reboot         Administrator is ending service on the NAS,
                        for example, prior to rebooting the NAS.

   Port Error           NAS detected an error on the port that
                        required ending the session.

   NAS Error            NAS detected an error (other than on the
                        port) that required ending the session.

   NAS Request          NAS ended the session for a non-error reason not
                        otherwise listed here.

   NAS Reboot           NAS ended the session to reboot
                        non-administratively ("crash").

   Port Unneeded        NAS ended the session because resource usage
                        fell below a low-water mark (for example, if
                        a bandwidth-on-demand algorithm decided that
                        the port was no longer needed).

   Port Preempted       NAS ended the session to allocate the
                        port to a higher priority use.

   Port Suspended       NAS ended the session to suspend a virtual
                        session.

   Service Unavailable  NAS was unable to provide requested service.

   Callback             NAS is terminating the current session
                        to perform callback for a new session.

   User Error           Input from user is in error, causing
                        session termination.

   Host Request         Login Host terminated session normally.

9.3.6.  Origin-AAA-Protocol

   The Origin-AAA-Protocol AVP (AVP Code 408) is of the type Enumerated
   and should be inserted in a Diameter message translated by a gateway
   system from another AAA protocol, such as RADIUS.  It identifies the
   source protocol of the message to the Diameter system receiving the
   message.

   The supported values are:

         1       RADIUS




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9.4.  Prohibited RADIUS Attributes

   The following RADIUS attributes MUST NOT appear in a Diameter
   message.  Instead, they are translated to other Diameter AVPs or
   handled in some special manner.  The rules for the treatment of the
   attributes are discussed in sections 9.1, 9.2, and 9.6.

   Attribute Description       Defined     Nearest Diameter AVP
   -----------------------------------------------------------------
    3 CHAP-Password            RFC 2865    CHAP-Auth Group
   26 Vendor-Specific          RFC 2865    Vendor Specific AVP
   29 Termination-Action       RFC 2865    Authorization-Lifetime
   40 Acct-Status-Type         RFC 2866    Accounting-Record-Type
   42 Acct-Input-Octets        RFC 2866    Accounting-Input-Octets
   43 Acct-Output-Octets       RFC 2866    Accounting-Output-Octets
   47 Acct-Input-Packets       RFC 2866    Accounting-Input-Packets
   48 Acct-Output-Packets      RFC 2866    Accounting-Output-Packets
   49 Acct-Terminate-Cause     RFC 2866    Termination-Cause
   52 Acct-Input-Gigawords     RFC 2869    Accounting-Input-Octets
   53 Acct-Output-Gigawords    RFC 2869    Accounting-Output-Octets
   80 Message-Authenticator    RFC 2869    none - check and discard

9.5.  Translatable Diameter AVPs

   In general, Diameter AVPs that are not RADIUS compatible have code
   values greater than 255.  The table in the section above shows the
   AVPs that can be converted into RADIUS attributes.

   Another problem may occur with Diameter AVP values that may be more
   than 253 octets in length.  Some RADIUS attributes (including but not
   limited to (8)Reply-Message, (79)EAP-Message, and (77)Connect-Info)
   allow concatenation of multiple instances to overcome this
   limitation.  If this is not possible, a Result-Code of
   DIAMETER_INVALID_AVP_LENGTH should be returned.

9.6.  RADIUS Vendor Specific Attributes

   RADIUS supports the inclusion of Vendor Specific Attributes (VSAs)
   through the use of attribute 26.  The recommended format [RADIUS] of
   the attribute data field includes a 4 octet vendor code followed by a
   one octet vendor type field and a one octet length field.  The last
   two fields MAY be repeated.

   A system communicating between Diameter and RADIUS MAY have specific
   knowledge of vendor formats, and MAY be able to translate between the
   two formats.  However, given the deployment of many RADIUS vendor
   formats that do not follow the example format in RFC 2865 [RADIUS],
   (e.g., those that use a longer vendor type code) the translations in



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   the next two sections will not work in general for those VSAs.  RFC
   2865 states that a robust implementation SHOULD support the field as
   undistinguished octets.

   Systems that don't have vendor format knowledge MAY discard such
   attributes without knowing a suitable translation.  An alternative
   format is under consideration [VSA], which proposes encodings that
   would preserve the native information and not require vendor
   knowledge in the gateway system.

   The following sections are an example for translating RADIUS VSAs
   that use the example RADIUS format, and Diameter VSAs that have type
   codes less than 255, and value field lengths less than 252.

9.6.1.  Forwarding a Diameter Vendor Specific AVP as a RADIUS VSA

   For Type codes less than 255, the value field length MUST be less
   than 252 or the AVP will be discarded.  The RADIUS VSA attribute
   should consist of the following fields;

      RADIUS Type = 26, Vendor Specific Attribute
      RADIUS Length = total length of attribute (header + data)
      RADIUS Vendor code = Diameter Vendor code
      RADIUS Vendor type code = low order byte of Diameter AVP code
      RADIUS Vendor data length = length of Diameter data

   If the Diameter AVP code is greater than 255, then the RADIUS
   speaking code may use a Vendor specific field coding, if it knows one
   for that vendor.  Otherwise, the AVP will be ignored.  If it is
   flagged as Mandatory, a "DIAMETER_AVP_UNSUPPORTED" Result-Code will
   be returned, and the RADIUS message will not be sent.

9.6.2.  Forwarding a RADIUS VSA as a Diameter Vendor Specific AVP

   The Diameter AVP will consist of the following fields:

      Diameter Flags: V=1, M=0, P=0
      Diameter Vendor code = RADIUS VSA Vendor code
      Diameter AVP code = RADIUS VSA Vendor type code
      Diameter AVP length = length of AVP (header + data)
      Diameter Data = RADIUS VSA vendor data

   Note that the VSAs are considered optional by RADIUS rules, and this
   specification does not set the Mandatory flag.  If an implementor
   desires a VSA be made mandatory because it represents a required
   service policy, the RADIUS gateway should have a process to set the
   bit on the Diameter side.




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   If the RADIUS receiving code knows of vendor specific field
   interpretations for the specific vendor, it may employ them to parse
   an extended AVP code or data length.  Otherwise the recommended
   standard fields will be used.

   Nested Multiple vendor data fields MUST be expanded into multiple
   Diameter AVPs.

10.  AVP Occurrence Tables

   The following tables present the AVPs used by NAS applications in NAS
   messages and specify in which Diameter messages they MAY or MAY NOT
   be present.  [BASE] messages and AVPs are not described in this
   document.  Note that AVPs that can only be present within a Grouped
   AVP are not represented in this table.

   The table uses the following symbols:

      0     The AVP MUST NOT be present in the message.
      0+    Zero or more instances of the AVP MAY be present in the
            message.
      0-1   Zero or one instance of the AVP MAY be present in the
            message.
      1     One instance of the AVP MUST be present in the message.

10.1.  AA-Request/Answer AVP Table

   The table in this section is limited to the Command Codes defined in
   this specification.

                                 +-----------+
                                 |  Command  |
                                 |-----+-----+
   Attribute Name                | AAR | AAA |
   ------------------------------|-----+-----+
   Acct-Interim-Interval         | 0   | 0-1 |
   ARAP-Challenge-Response       | 0   | 0-1 |
   ARAP-Features                 | 0   | 0-1 |
   ARAP-Password                 | 0-1 | 0   |
   ARAP-Security                 | 0-1 | 0-1 |
   ARAP-Security-Data            | 0+  | 0+  |
   ARAP-Zone-Access              | 0   | 0-1 |
   Auth-Application-Id           | 1   | 1   |
   Auth-Grace-Period             | 0-1 | 0-1 |
   Auth-Request-Type             | 1   | 1   |
   Auth-Session-State            | 0-1 | 0-1 |
   Authorization-Lifetime        | 0-1 | 0-1 |
   ------------------------------|-----+-----+



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                                 +-----------+
                                 |  Command  |
                                 |-----+-----+
   Attribute Name                | AAR | AAA |
   ------------------------------|-----+-----+
   Callback-Id                   | 0   | 0-1 |
   Callback-Number               | 0-1 | 0-1 |
   Called-Station-Id             | 0-1 | 0   |
   Calling-Station-Id            | 0-1 | 0   |
   CHAP-Auth                     | 0-1 | 0   |
   CHAP-Challenge                | 0-1 | 0   |
   Class                         | 0   | 0+  |
   Configuration-Token           | 0   | 0+  |
   Connect-Info                  | 0+  | 0   |
   Destination-Host              | 0-1 | 0   |
   Destination-Realm             | 1   | 0   |
   Error-Message                 | 0   | 0-1 |
   Error-Reporting-Host          | 0   | 0-1 |
   Failed-AVP                    | 0+  | 0+  |
   Filter-Id                     | 0   | 0+  |
   Framed-Appletalk-Link         | 0   | 0-1 |
   Framed-Appletalk-Network      | 0   | 0+  |
   Framed-Appletalk-Zone         | 0   | 0-1 |
   Framed-Compression            | 0+  | 0+  |
   Framed-Interface-Id           | 0-1 | 0-1 |
   Framed-IP-Address             | 0-1 | 0-1 |
   Framed-IP-Netmask             | 0-1 | 0-1 |
   Framed-IPv6-Prefix            | 0+  | 0+  |
   Framed-IPv6-Pool              | 0   | 0-1 |
   Framed-IPv6-Route             | 0   | 0+  |
   Framed-IPX-Network            | 0   | 0-1 |
   Framed-MTU                    | 0-1 | 0-1 |
   Framed-Pool                   | 0   | 0-1 |
   Framed-Protocol               | 0-1 | 0-1 |
   Framed-Route                  | 0   | 0+  |
   Framed-Routing                | 0   | 0-1 |
   Idle-Timeout                  | 0   | 0-1 |
   Login-IP-Host                 | 0+  | 0+  |
   Login-IPv6-Host               | 0+  | 0+  |
   Login-LAT-Group               | 0-1 | 0-1 |
   Login-LAT-Node                | 0-1 | 0-1 |
   Login-LAT-Port                | 0-1 | 0-1 |
   Login-LAT-Service             | 0-1 | 0-1 |
   Login-Service                 | 0   | 0-1 |
   Login-TCP-Port                | 0   | 0-1 |
   Multi-Round-Time-Out          | 0   | 0-1 |
   ------------------------------|-----+-----+




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                                 +-----------+
                                 |  Command  |
                                 |-----+-----+
   Attribute Name                | AAR | AAA |
   ------------------------------|-----+-----+
   NAS-Filter-Rule               | 0   | 0+  |
   NAS-Identifier                | 0-1 | 0   |
   NAS-IP-Address                | 0-1 | 0   |
   NAS-IPv6-Address              | 0-1 | 0   |
   NAS-Port                      | 0-1 | 0   |
   NAS-Port-Id                   | 0-1 | 0   |
   NAS-Port-Type                 | 0-1 | 0   |
   Origin-AAA-Protocol           | 0-1 | 0-1 |
   Origin-Host                   | 1   | 1   |
   Origin-Realm                  | 1   | 1   |
   Origin-State-Id               | 0-1 | 0-1 |
   Originating-Line-Info         | 0-1 | 0   |
   Password-Retry                | 0   | 0-1 |
   Port-Limit                    | 0-1 | 0-1 |
   Prompt                        | 0   | 0-1 |
   Proxy-Info                    | 0+  | 0+  |
   QoS-Filter-Rule               | 0   | 0+  |
   Re-Auth-Request-Type          | 0   | 0-1 |
   Redirect-Host                 | 0   | 0+  |
   Redirect-Host-Usage           | 0   | 0-1 |
   Redirect-Max-Cache-Time       | 0   | 0-1 |
   Reply-Message                 | 0   | 0+  |
   Result-Code                   | 0   | 1   |
   Route-Record                  | 0+  | 0+  |
   Service-Type                  | 0-1 | 0-1 |
   Session-Id                    | 1   | 1   |
   Session-Timeout               | 0   | 0-1 |
   State                         | 0-1 | 0-1 |
   Tunneling                     | 0+  | 0+  |
   User-Name                     | 0-1 | 0-1 |
   User-Password                 | 0-1 | 0   |
   ------------------------------|-----+-----+

10.2.  Accounting AVP Tables

   The tables in this section are used to show which AVPs defined in
   this document are to be present and used in NAS application
   Accounting messages.  These AVPs are defined in this document, as
   well as in [BASE] and [RADIUSAcct].







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10.2.1.  Accounting Framed Access AVP Table

   The table in this section is used when the Service-Type specifies
   Framed Access.

                                          +-----------+
                                          |  Command  |
                                          |-----+-----+
   Attribute Name                         | ACR | ACA |
   ---------------------------------------|-----+-----+
   Accounting-Auth-Method                 | 0-1 | 0   |
   Accounting-Input-Octets                | 1   | 0   |
   Accounting-Input-Packets               | 1   | 0   |
   Accounting-Output-Octets               | 1   | 0   |
   Accounting-Output-Packets              | 1   | 0   |
   Accounting-Record-Number               | 0-1 | 0-1 |
   Accounting-Record-Type                 | 1   | 1   |
   Accounting-Realtime-Required           | 0-1 | 0-1 |
   Accounting-Sub-Session-Id              | 0-1 | 0-1 |
   Acct-Application-Id                    | 0-1 | 0-1 |
   Acct-Session-Id                        | 1   | 0-1 |
   Acct-Multi-Session-Id                  | 0-1 | 0-1 |
   Acct-Authentic                         | 1   | 0   |
   Acct-Delay-Time                        | 0-1 | 0   |
   Acct-Interim-Interval                  | 0-1 | 0-1 |
   Acct-Link-Count                        | 0-1 | 0   |
   Acct-Session-Time                      | 1   | 0   |
   Acct-Tunnel-Connection                 | 0-1 | 0   |
   Acct-Tunnel-Packets-Lost               | 0-1 | 0   |
   Authorization-Lifetime                 | 0-1 | 0   |
   Callback-Id                            | 0-1 | 0   |
   Callback-Number                        | 0-1 | 0   |
   Called-Station-Id                      | 0-1 | 0   |
   Calling-Station-Id                     | 0-1 | 0   |
   Class                                  | 0+  | 0+  |
   Connection-Info                        | 0+  | 0   |
   Destination-Host                       | 0-1 | 0   |
   Destination-Realm                      | 1   | 0   |
   Event-Timestamp                        | 0-1 | 0-1 |
   Error-Message                          | 0   | 0-1 |
   Error-Reporting-Host                   | 0   | 0-1 |
   Failed-AVP                             | 0   | 0+  |
   ---------------------------------------|-----+-----+








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                                          +-----------+
                                          |  Command  |
                                          |-----+-----+
   Attribute Name                         | ACR | ACA |
   ---------------------------------------|-----+-----+
   Framed-AppleTalk-Link                  | 0-1 | 0   |
   Framed-AppleTalk-Network               | 0-1 | 0   |
   Framed-AppleTalk-Zone                  | 0-1 | 0   |
   Framed-Compression                     | 0-1 | 0   |
   Framed-IP-Address                      | 0-1 | 0   |
   Framed-IP-Netmask                      | 0-1 | 0   |
   Framed-IPv6-Prefix                     | 0+  | 0   |
   Framed-IPv6-Pool                       | 0-1 | 0   |
   Framed-IPX-Network                     | 0-1 | 0   |
   Framed-MTU                             | 0-1 | 0   |
   Framed-Pool                            | 0-1 | 0   |
   Framed-Protocol                        | 0-1 | 0   |
   Framed-Route                           | 0-1 | 0   |
   Framed-Routing                         | 0-1 | 0   |
   NAS-Filter-Rule                        | 0+  | 0   |
   NAS-Identifier                         | 0-1 | 0-1 |
   NAS-IP-Address                         | 0-1 | 0-1 |
   NAS-IPv6-Address                       | 0-1 | 0-1 |
   NAS-Port                               | 0-1 | 0-1 |
   NAS-Port-Id                            | 0-1 | 0-1 |
   NAS-Port-Type                          | 0-1 | 0-1 |
   Origin-AAA-Protocol                    | 0-1 | 0-1 |
   Origin-Host                            | 1   | 1   |
   Origin-Realm                           | 1   | 1   |
   Origin-State-Id                        | 0-1 | 0-1 |
   Originating-Line-Info                  | 0-1 | 0   |
   Proxy-Info                             | 0+  | 0+  |
   QoS-Filter-Rule                        | 0+  | 0   |
   Route-Record                           | 0+  | 0+  |
   Result-Code                            | 0   | 1   |
   Service-Type                           | 0-1 | 0-1 |
   Session-Id                             | 1   | 1   |
   Termination-Cause                      | 0-1 | 0-1 |
   Tunnel-Assignment-Id                   | 0-1 | 0   |
   Tunnel-Client-Endpoint                 | 0-1 | 0   |
   Tunnel-Medium-Type                     | 0-1 | 0   |
   Tunnel-Private-Group-Id                | 0-1 | 0   |
   Tunnel-Server-Endpoint                 | 0-1 | 0   |
   Tunnel-Type                            | 0-1 | 0   |
   User-Name                              | 0-1 | 0-1 |
   Vendor-Specific-Application-Id         | 0-1 | 0-1 |
   ---------------------------------------|-----+-----+




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10.2.2.  Accounting Non-Framed Access AVP Table

   The table in this section is used when the Service-Type specifies
   Non-Framed Access.

                                          +-----------+
                                          |  Command  |
                                          |-----+-----+
   Attribute Name                         | ACR | ACA |
   ---------------------------------------|-----+-----+
   Accounting-Auth-Method                 | 0-1 | 0   |
   Accounting-Input-Octets                | 1   | 0   |
   Accounting-Output-Octets               | 1   | 0   |
   Accounting-Record-Type                 | 1   | 1   |
   Accounting-Record-Number               | 0-1 | 0-1 |
   Accounting-Realtime-Required           | 0-1 | 0-1 |
   Accounting-Sub-Session-Id              | 0-1 | 0-1 |
   Acct-Application-Id                    | 0-1 | 0-1 |
   Acct-Session-Id                        | 1   | 0-1 |
   Acct-Multi-Session-Id                  | 0-1 | 0-1 |
   Acct-Authentic                         | 1   | 0   |
   Acct-Delay-Time                        | 0-1 | 0   |
   Acct-Interim-Interval                  | 0-1 | 0-1 |
   Acct-Link-Count                        | 0-1 | 0   |
   Acct-Session-Time                      | 1   | 0   |
   Authorization-Lifetime                 | 0-1 | 0   |
   Callback-Id                            | 0-1 | 0   |
   Callback-Number                        | 0-1 | 0   |
   Called-Station-Id                      | 0-1 | 0   |
   Calling-Station-Id                     | 0-1 | 0   |
   Class                                  | 0+  | 0+  |
   Connection-Info                        | 0+  | 0   |
   Destination-Host                       | 0-1 | 0   |
   Destination-Realm                      | 1   | 0   |
   Event-Timestamp                        | 0-1 | 0-1 |
   Error-Message                          | 0   | 0-1 |
   Error-Reporting-Host                   | 0   | 0-1 |
   Failed-AVP                             | 0   | 0+  |
   Login-IP-Host                          | 0+  | 0   |
   Login-IPv6-Host                        | 0+  | 0   |
   Login-LAT-Service                      | 0-1 | 0   |
   Login-LAT-Node                         | 0-1 | 0   |
   Login-LAT-Group                        | 0-1 | 0   |
   Login-LAT-Port                         | 0-1 | 0   |
   Login-Service                          | 0-1 | 0   |
   Login-TCP-Port                         | 0-1 | 0   |
   ---------------------------------------|-----+-----+




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                                          +-----------+
                                          |  Command  |
                                          |-----+-----+
   Attribute Name                         | ACR | ACA |
   ---------------------------------------|-----+-----+
   NAS-Identifier                         | 0-1 | 0-1 |
   NAS-IP-Address                         | 0-1 | 0-1 |
   NAS-IPv6-Address                       | 0-1 | 0-1 |
   NAS-Port                               | 0-1 | 0-1 |
   NAS-Port-Id                            | 0-1 | 0-1 |
   NAS-Port-Type                          | 0-1 | 0-1 |
   Origin-AAA-Protocol                    | 0-1 | 0-1 |
   Origin-Host                            | 1   | 1   |
   Origin-Realm                           | 1   | 1   |
   Origin-State-Id                        | 0-1 | 0-1 |
   Originating-Line-Info                  | 0-1 | 0   |
   Proxy-Info                             | 0+  | 0+  |
   QoS-Filter-Rule                        | 0+  | 0   |
   Route-Record                           | 0+  | 0+  |
   Result-Code                            | 0   | 1   |
   Session-Id                             | 1   | 1   |
   Service-Type                           | 0-1 | 0-1 |
   Termination-Cause                      | 0-1 | 0-1 |
   User-Name                              | 0-1 | 0-1 |
   Vendor-Specific-Application-Id         | 0-1 | 0-1 |
   ---------------------------------------|-----+-----+

11.  IANA Considerations

   This section provides guidance to the Internet Assigned Numbers
   Authority (IANA) regarding registration of values related to the
   Diameter protocol, in accordance with BCP 26 [IANAConsid].

   This document defines values in the namespaces that have been created
   and defined in the Diameter Base [BASE].  The IANA Considerations
   section of that document details the assignment criteria.  Values
   assigned in this document, or by future IANA action, must be
   coordinated within this shared namespace.

11.1.  Command Codes

   This specification assigns the value 265 from the Command Code
   namespace defined in [BASE].  See sections 3.1 and 3.2 for the
   assignment of the namespace in this specification.







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11.2.  AVP Codes

   This specification assigns the values 363 - 366 and 400 - 408 from
   the AVP Code namespace defined in [BASE].  See sections 4 and 5 for
   the assignment of the namespace in this specification.  Note that the
   values 363 - 366 are jointly, but consistently, assigned in
   [DiamMIP].  This document also creates one new namespace to be
   managed by IANA, as described in section 11.5.

   This specification also specifies the use of AVPs in the 0 - 255
   range, which are defined in [RADIUSTypes].  These values are assigned
   by the policy in RFC 2865 section 6 [RADIUS] and are amended by RFC
   3575 [RADIUSIANA].

11.3.  Application Identifier

   This specification uses the value one (1) in the Application
   Identifier namespace as assigned in [BASE].  See section 1.2 above
   for more information.

11.4.  CHAP-Algorithm AVP Values

   As defined in section 5.5, the CHAP-Algorithm AVP (AVP Code 403) uses
   the values of the "PPP AUTHENTICATION ALGORITHMS" namespace defined
   in [PPPCHAP].

11.5.  Accounting-Auth-Method AVP Values

   As defined in section 8.6, the Accounting-Auth-Method AVP (AVP Code
   406) defines the values 1 - 5.  All remaining values are available
   for assignment via IETF Consensus [IANA].

11.6.  Origin-AAA-Protocol AVP Values

   As defined in section 9.3.6, the Origin-AAA-Protocol AVP (AVP Code
   408) defines the value 1. All remaining values are available for
   assignment with a "Specification Required" policy [IANAConsid].

12.  Security Considerations

   This document describes the extension of Diameter for the NAS
   application.  The security considerations of the Diameter protocol
   itself have been discussed in [BASE].  Use of this application of
   Diameter MUST take into consideration the security issues and
   requirements of the Base protocol.






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   This document does not contain a security protocol but does discuss
   how PPP authentication protocols can be carried within the Diameter
   protocol.  The PPP authentication protocols described are PAP and
   CHAP.

   The use of PAP SHOULD be discouraged, as it exposes users' passwords
   to possibly non-trusted entities.  However, PAP is also frequently
   used for use with One-Time Passwords, which do not expose a security
   risk.

   This document also describes how CHAP can be carried within the
   Diameter protocol, which is required for RADIUS backward
   compatibility.  The CHAP protocol, as used in a RADIUS environment,
   facilitates authentication replay attacks.

   The use of the EAP authentication protocols described in [DiamEAP]
   can offer better security, given a method suitable for the
   circumstances.

13.  References

13.1.  Normative References

   [BASE]         Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and
                  J. Arkko, "Diameter Base Protocol", RFC 3588,
                  September 2003.

   [DiamTrans]    Aboba, B. and J. Wood, "Authentication, Authorization
                  and Accounting (AAA) Transport Profile", RFC 3539,
                  June 2003.

   [RADIUS]       Rigney, C., Willens, S., Rubens, A., and W. Simpson,
                  "Remote Authentication Dial In User Service (RADIUS)",
                  RFC 2865, June 2000.

   [RADIUSTypes]  IANA, "RADIUS Types", URL:
                  <http://www.iana.org/assignments/radius-types>

   [RADIUSIPv6]   Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
                  RFC 3162, August 2001.

   [IPv6Addr]     Nerenberg, L., "IMAP4 Binary Content Extension", RFC
                  3516, April 2003.

   [PPPCHAP]      Simpson, W., "PPP Challenge Handshake Authentication
                  Protocol (CHAP)", RFC 1994, August 1996.





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   [IANAConsid]   Narten, T. and H. Alvestrand, "Guidelines for Writing
                  an IANA Considerations Section in RFCs", BCP 26, RFC
                  2434, October 1998.

   [IANA]         IANA Assigned Numbers Database, URL:
                  <http://www.iana.org/numbers.html>

   [Keywords]     Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119, March 1997.

   [ANITypes]     NANPA Number Resource Info, ANI Assignments, URL:
                  <http://www.nanpa.com/number_resource_info/
                  ani_ii_assignments.html>

13.2.  Informative References

   [RADIUSAcct]   Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.

   [RADIUSExt]    Rigney, C., Willats, W., and P. Calhoun, "RADIUS
                  Extensions", RFC 2869, June 2000.

   [RADTunnels]   Zorn, G., Leifer, D., Rubens, A., Shriver, J.,
                  Holdrege, M., and I. Goyret, "RADIUS Attributes for
                  Tunnel Protocol Support", RFC 2868, June 2000.

   [RADTunlAcct]  Zorn, G., Aboba, B., and D. Mitton, "RADIUS Accounting
                  Modifications for Tunnel Protocol Support", RFC 2867,
                  June 2000.

   [RADDynAuth]   Chiba, M., Dommety, G., Eklund, M., Mitton, D., and B.
                  Aboba, "Dynamic Authorization Extensions to Remote
                  Authentication Dial In User Service (RADIUS)", RFC
                  3576, July 2003.

   [RADIUSIANA]   Aboba, B., "IANA Considerations for RADIUS (Remote
                  Authentication Dial In User Service)", RFC 3575, July
                  2003.

   [NASModel]     Mitton, D. and M. Beadles, "Network Access Server
                  Requirements Next Generation (NASREQNG) NAS Model",
                  RFC 2881, July 2000.

   [NASCriteria]  Beadles, M. and D. Mitton, "Criteria for Evaluating
                  Network Access Server Protocols", RFC 3169, September
                  2001.






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   [AAACriteria]  Aboba, B., Calhoun, P., Glass, S., Hiller, T., McCann,
                  P., Shiino, H., Zorn, G., Dommety, G., Perkins, C.,
                  Patil, B., Mitton, D., Manning, S., Beadles, M.,
                  Walsh, P., Chen, X., Sivalingham, S., Hameed, A.,
                  Munson, M., Jacobs, S., Lim, B., Hirschman, B., Hsu,
                  R., Xu, Y., Campbell, E., Baba, S., and E. Jaques,
                  "Criteria for Evaluating AAA Protocols for Network
                  Access", RFC 2989, November 2000.

   [DiamEAP]      Eronen, P., "Diameter EAP Application", Work in
                  Progress, May 2004.

   [DiamCMS]      Calhoun, P., Bulley, W., and S. Farrell, "Diameter CMS
                  Security Application", Work in Progress, March 2002.

   [DiamMIP]      Calhoun, P., Johansson, T., Perkins, C., Hiller, T.,
                  and P. McCann "Diameter Mobile IPv4 Application", RFC
                  4004, August 2005.

   [VSA]          Mitton, D., "Diameter/RADIUS Vendor Specific AVP
                  Translation", Work in Progress, April 2005.

   [RAD802.1X]    Congdon, P., Aboba, B., Smith, A., Zorn, G., and J.
                  Roese, "IEEE 802.1X Remote Authentication Dial In User
                  Service (RADIUS) Usage Guidelines", RFC 3580,
                  September 2003.

   [CDMA2000]     3GPP2 "P.S0001-B", Wireless IP Network Standard,
                  October 2002.
                  http://www.3gpp2.com/Public_html/specs/P.S0001-
                  B_v1.0.pdf

   [AppleTalk]    Sidhu, Gursharan; Andrews, Richard F. & Oppenheimer,
                  Alan B.  "Inside AppleTalk", Second Edition, Apple
                  Computer., 1990

   [ARAP]         Apple Remote Access Protocol (ARAP) Version 2.0
                  External Reference Specification", Apple Computer,
                  September 1994, R0612LL/B

   [IPX]          Novell, Inc., "NetWare System Technical Interface
                  Overview", June 1989,  # 883-000780-001

   [LAT]          Local Area Transport (LAT) Specification V5.0, Digital
                  Equipment Corp., AA-NL26A-TE, June 1989






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   [DIFFSERV]     Nichols, K., Blake, S., Baker, F., and D. Black,
                  "Definition of the Differentiated Services Field (DS
                  Field) in the IPv4 and IPv6 Headers", RFC 2474,
                  December 1998.

   [DIFFSERVAF]   Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
                  "Assured Forwarding PHB Group", RFC 2597, June 1999.

   [DIFFSERVEF]   Davie, B., Charny, A., Bennet, J.C., Benson, K., Le
                  Boudec, J., Courtney, W., Davari, S., Firoiu, V., and
                  D. Stiliadis, "An Expedited Forwarding PHB (Per-Hop
                  Behavior)", RFC 3246, March 2002.

   [UTF-8]        Yergeau, F., "UTF-8, a transformation format of ISO
                  10646", STD 63, RFC 3629, November 2003.

   [ISOLatin]     ISO 8859. International Standard -- Information
                  Processing -- 8-bit Single-Byte Coded Graphic
                  Character Sets -- Part 1: Latin Alphabet No. 1, ISO
                  8859-1:1987.  URL:
                  <http://www.iso.ch/cate/d16338.html>

   [PPP]          Simpson, W., "The Point-to-Point Protocol (PPP)", STD
                  51, RFC 1661, July 1994.

   [PAP]          Lloyd, B. and W. Simpson, "PPP Authentication
                  Protocols", RFC 1334, October 1992.

   [L2TP]         Townsley, W., Valencia, A., Rubens, A., Pall, G.,
                  Zorn, G., and B. Palter, "Layer Two Tunneling Protocol
                  "L2TP"", RFC 2661, August 1999.

   [PPPMP]        Sklower, K., Lloyd, B., McGregor, G., Carr, D., and T.
                  Coradetti, "The PPP Multilink Protocol (MP)", RFC
                  1990, August 1996.

   [PPTP]         Hamzeh, K., Pall, G., Verthein, W., Taarud, J.,
                  Little, W., and G. Zorn, "Point-to-Point Tunneling
                  Protocol", RFC 2637, July 1999.

   [IEEE 802.11F] IEEE, "Trial-Use Recommended Practice for Multi-Vendor
                  Access Point Interoperability via an Inter-Access
                  Point Protocol Across Distribution Systems Supporting
                  IEEE 802.11 Operation", IEEE 802.11F-2003, June 2003.







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14.  Acknowledgements

   The authors would like to thank Carl Rigney, Allan C. Rubens, William
   Allen Simpson, and Steve Willens for their work on the original
   RADIUS [RADIUS], from which many of the concepts in this
   specification were derived.  Thanks, also, to Carl Rigney for
   [RADIUSAcct] and [RADIUSExt]; Ward Willats for [RADIUSExt]; Glen
   Zorn, Bernard Aboba, and Dave Mitton for [RADTunlAcct] and
   [RADIUSIPv6]; and Dory Leifer, John Shriver, Matt Holdrege, and
   Ignacio Goyret for their work on [RADTunnels].  This document stole
   text and concepts from both [RADTunnels] and [RADIUSExt].  Thanks go
   to Carl Williams for providing IPv6-specific text.

   The authors would also like to acknowledge the following people for
   their contributions in the development of the Diameter protocol:
   Bernard Aboba, Jari Arkko, William Bulley, Kuntal Chowdhury, Daniel
   C. Fox, Lol Grant, Nancy Greene, Jeff Hagg, Peter Heitman, Paul
   Krumviede, Fergal Ladley, Ryan Moats, Victor Muslin, Kenneth Peirce,
   Sumit Vakil, John R. Vollbrecht, and Jeff Weisberg.

   Finally, Pat Calhoun would like to thank Sun Microsystems, as most of
   the effort put into this document was done while he was in their
   employ.




























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Authors' Addresses

   Pat Calhoun
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, CA 95134
   USA

   Phone: +1 408-853-5269
   EMail: [email protected]


   Glen Zorn
   Cisco Systems, Inc.
   500 108th Avenue N.E., Suite 500
   Bellevue, WA 98004
   USA

   Phone:  1 425-471-4861
   EMail: [email protected]


   David Spence
   3259 Bluett Rd.
   Ann Arbor, MI  48105
   USA

   Phone: +1 734 834 6481
   EMail: [email protected]


   David Mitton
   Circular Networks
   733 Turnpike St #154
   North Andover, MA 01845

   EMail: [email protected]














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Full Copyright Statement

   Copyright (C) The Internet Society (2005).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

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Acknowledgement

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   Internet Society.







Calhoun, et al.             Standards Track                    [Page 85]