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RFC 7155 - Diameter Network Access Server Application


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Internet Engineering Task Force (IETF)                      G. Zorn, Ed.
Request for Comments: 7155                                   Network Zen
Obsoletes: 4005                                               April 2014
Category: Standards Track
ISSN: 2070-1721

               Diameter Network Access Server Application

Abstract

   This document describes the Diameter protocol application used for
   Authentication, Authorization, and Accounting services in the Network
   Access Server (NAS) environment; it obsoletes RFC 4005.  When
   combined with the Diameter Base protocol, Transport Profile, and
   Extensible Authentication Protocol specifications, this application
   specification satisfies typical network access services requirements.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7155.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................4
      1.1. Changes from RFC 4005 ......................................5
      1.2. Terminology ................................................6
      1.3. Requirements Language ......................................7
      1.4. Advertising Application Support ............................8
      1.5. Application Identification .................................8
      1.6. Accounting Model ...........................................8
   2. NAS Calls, Ports, and Sessions ..................................8
      2.1. Diameter Session Establishment .............................9
      2.2. Diameter Session Reauthentication or Reauthorization .......9
      2.3. Diameter Session Termination ..............................10
   3. Diameter NAS Application Messages ..............................11
      3.1. AA-Request (AAR) Command ..................................11
      3.2. AA-Answer (AAA) Command ...................................13
      3.3. Re-Auth-Request (RAR) Command .............................15
      3.4. Re-Auth-Answer (RAA) Command ..............................16
      3.5. Session-Termination-Request (STR) Command .................17
      3.6. Session-Termination-Answer (STA) Command ..................17
      3.7. Abort-Session-Request (ASR) Command .......................18
      3.8. Abort-Session-Answer (ASA) Command ........................19
      3.9. Accounting-Request (ACR) Command ..........................20
      3.10. Accounting-Answer (ACA) Command ..........................22
   4. Diameter NAS Application AVPs ..................................23
      4.1. Derived AVP Data Formats ..................................23
           4.1.1. QoSFilterRule ......................................23
      4.2. NAS Session AVPs ..........................................24
           4.2.1. Call and Session Information .......................24
           4.2.2. NAS-Port AVP .......................................25
           4.2.3. NAS-Port-Id AVP ....................................25
           4.2.4. NAS-Port-Type AVP ..................................26
           4.2.5. Called-Station-Id AVP ..............................26
           4.2.6. Calling-Station-Id AVP .............................26
           4.2.7. Connect-Info AVP ...................................27
           4.2.8. Originating-Line-Info AVP ..........................27
           4.2.9. Reply-Message AVP ..................................28
      4.3. NAS Authentication AVPs ...................................28
           4.3.1. User-Password AVP ..................................29
           4.3.2. Password-Retry AVP .................................29
           4.3.3. Prompt AVP .........................................29
           4.3.4. CHAP-Auth AVP ......................................29
           4.3.5. CHAP-Algorithm AVP .................................30
           4.3.6. CHAP-Ident AVP .....................................30
           4.3.7. CHAP-Response AVP ..................................30
           4.3.8. CHAP-Challenge AVP .................................30
           4.3.9. ARAP-Password AVP ..................................30
           4.3.10. ARAP-Challenge-Response AVP .......................31

           4.3.11. ARAP-Security AVP .................................31
           4.3.12. ARAP-Security-Data AVP ............................31
      4.4. NAS Authorization AVPs ....................................31
           4.4.1. Service-Type AVP ...................................33
           4.4.2. Callback-Number AVP ................................34
           4.4.3. Callback-Id AVP ....................................34
           4.4.4. Idle-Timeout AVP ...................................34
           4.4.5. Port-Limit AVP .....................................34
           4.4.6. NAS-Filter-Rule AVP ................................35
           4.4.7. Filter-Id AVP ......................................35
           4.4.8. Configuration-Token AVP ............................35
           4.4.9. QoS-Filter-Rule AVP ................................35
           4.4.10. Framed Access Authorization AVPs ..................36
                  4.4.10.1. Framed-Protocol AVP ......................36
                  4.4.10.2. Framed-Routing AVP .......................36
                  4.4.10.3. Framed-MTU AVP ...........................37
                  4.4.10.4. Framed-Compression AVP ...................37
                  4.4.10.5. IP Access Authorization AVPs .............37
                           4.4.10.5.1. Framed-IP-Address AVP .........37
                           4.4.10.5.2. Framed-IP-Netmask AVP .........37
                           4.4.10.5.3. Framed-Route AVP ..............38
                           4.4.10.5.4. Framed-Pool AVP ...............38
                           4.4.10.5.5. Framed-Interface-Id AVP .......38
                           4.4.10.5.6. Framed-IPv6-Prefix AVP ........39
                           4.4.10.5.7. Framed-IPv6-Route AVP .........39
                           4.4.10.5.8. Framed-IPv6-Pool AVP ..........39
                  4.4.10.6. IPX Access AVPs ..........................39
                           4.4.10.6.1. Framed-IPX-Network AVP ........40
                  4.4.10.7. AppleTalk Network Access AVPs ............40
                           4.4.10.7.1. Framed-Appletalk-Link AVP .....40
                           4.4.10.7.2. Framed-Appletalk-Network AVP ..40
                           4.4.10.7.3. Framed-Appletalk-Zone AVP .....41
                  4.4.10.8. AppleTalk Remote Access AVPs .............41
                           4.4.10.8.1. ARAP-Features AVP .............41
                           4.4.10.8.2. ARAP-Zone-Access AVP ..........41
           4.4.11. Non-Framed Access Authorization AVPs ..............41
                  4.4.11.1. Login-IP-Host AVP ........................41
                  4.4.11.2. Login-IPv6-Host AVP ......................42
                  4.4.11.3. Login-Service AVP ........................42
                  4.4.11.4. TCP Services .............................42
                           4.4.11.4.1. Login-TCP-Port AVP ............42
                  4.4.11.5. LAT Services .............................43
                           4.4.11.5.1. Login-LAT-Service AVP .........43
                           4.4.11.5.2. Login-LAT-Node AVP ............43
                           4.4.11.5.3. Login-LAT-Group AVP ...........44
                           4.4.11.5.4. Login-LAT-Port AVP ............44
      4.5. NAS Tunneling AVPs ........................................45
           4.5.1. Tunneling AVP ......................................45

           4.5.2. Tunnel-Type AVP ....................................46
           4.5.3. Tunnel-Medium-Type AVP .............................46
           4.5.4. Tunnel-Client-Endpoint AVP .........................46
           4.5.5. Tunnel-Server-Endpoint AVP .........................47
           4.5.6. Tunnel-Password AVP ................................48
           4.5.7. Tunnel-Private-Group-Id AVP ........................48
           4.5.8. Tunnel-Assignment-Id AVP ...........................48
           4.5.9. Tunnel-Preference AVP ..............................50
           4.5.10. Tunnel-Client-Auth-Id AVP .........................50
           4.5.11. Tunnel-Server-Auth-Id AVP .........................50
      4.6. NAS Accounting AVPs .......................................51
           4.6.1. Accounting-Input-Octets AVP ........................52
           4.6.2. Accounting-Output-Octets AVP .......................52
           4.6.3. Accounting-Input-Packets AVP .......................52
           4.6.4. Accounting-Output-Packets AVP ......................53
           4.6.5. Acct-Session-Time AVP ..............................53
           4.6.6. Acct-Authentic AVP .................................53
           4.6.7. Accounting-Auth-Method AVP .........................53
           4.6.8. Acct-Delay-Time AVP ................................53
           4.6.9. Acct-Link-Count AVP ................................54
           4.6.10. Acct-Tunnel-Connection AVP ........................55
           4.6.11. Acct-Tunnel-Packets-Lost AVP ......................55
   5. AVP Occurrence Tables ..........................................55
      5.1. AA-Request / AA-Answer AVP Table ..........................56
      5.2. Accounting AVP Tables .....................................58
           5.2.1. Framed Access Accounting AVP Table .................59
           5.2.2. Non-Framed Access Accounting AVP Table .............61
   6. Unicode Considerations .........................................62
   7. IANA Considerations ............................................63
   8. Security Considerations ........................................63
      8.1. Authentication Considerations .............................63
      8.2. AVP Considerations ........................................64
   9. References .....................................................65
      9.1. Normative References ......................................65
      9.2. Informative References ....................................65
   Appendix A. Acknowledgements ......................................69
     A.1. This Document ..............................................69
     A.2. RFC 4005 ...................................................69

1.  Introduction

   This document describes the Diameter protocol application used for
   Authentication, Authorization, and Accounting in the Network Access
   Server (NAS) environment.  When combined with the Diameter Base
   protocol [RFC6733], Transport Profile [RFC3539], and Extensible
   Authentication Protocol (EAP) [RFC4072] specifications, this
   specification satisfies the NAS-related requirements defined in
   [RFC2989] and [RFC3169].

   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.

1.1.  Changes from RFC 4005

   This document obsoletes [RFC4005] and is not backward compatible with
   that document.  An overview of some of the major changes is given
   below.

   o  All of the material regarding RADIUS/Diameter protocol
      interactions has been removed; however, where AVPs are derived
      from RADIUS Attributes, the range and format of those Attribute
      values have been retained for ease of transition.

   o  The Command Code Format (CCF) [RFC6733] for the Accounting-Request
      and Accounting-Answer messages has been changed to explicitly
      require the inclusion of the Acct-Application-Id AVP and exclude
      the Vendor-Specific-Application-Id AVP.  Normally, this type of
      change would require the allocation of a new command code (see
      Section 1.3.3 of [RFC6733]) and consequently, a new application-
      id.  However, the presence of an instance of the Acct-Application-
      Id AVP was required in [RFC4005], as well:

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

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

      Thus, though the syntax of the commands has changed, the semantics
      have not (with the caveat that the Acct-Application-Id AVP can no
      longer be contained in the Vendor-Specific-Application-Id AVP).

   o  The lists of RADIUS attribute values have been deleted in favor of
      references to the appropriate IANA registries.

   o  The accounting model to be used is now specified (see
      Section 1.6).

   There are many other miscellaneous fixes that have been introduced in
   this document that may not be considered significant, but they are
   useful nonetheless.  Examples are fixes to example IP addresses,
   addition of clarifying references, etc.  Errata reports filed against
   [RFC4005] at the time of writing have been reviewed and incorporated
   as necessary.  A comprehensive list of changes is not shown here for
   practical reasons.

1.2.  Terminology

   Section 1.2 of the Diameter Base protocol specification [RFC6733]
   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 [RFC2881].

   PPP (Point-to-Point Protocol)

      A multiprotocol serial datalink.  PPP is the primary IP datalink
      used for dial-in NAS connection service [RFC1661].

   CHAP (Challenge Handshake Authentication Protocol)

      An authentication process used in PPP [RFC1994].

   PAP (Password Authentication Protocol)

      A deprecated PPP authentication process, but often used for
      backward compatibility [RFC1334].

   SLIP (Serial Line Internet 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 (Internetwork Packet Exchange)

      The network protocol used by NetWare networks [IPX].

   L2TP (Layer Two Tunneling Protocol)

      L2TP [RFC3931] provides a dynamic mechanism for tunneling Layer 2
      "circuits" across a packet-oriented data network.

   LAC (L2TP Access Concentrator)

      An L2TP Control Connection Endpoint being used to cross-connect an
      L2TP session directly to a datalink [RFC3931].

   LAT (Local Area Transport)

      A Digital Equipment Corp.  LAN protocol for terminal services
      [LAT].

   LCP (Link Control Protocol)

      One of the three major components of PPP [RFC1661].  LCP is used
      to automatically agree upon encapsulation format options, handle
      varying limits on sizes of packets, detect a looped-back link and
      other common misconfiguration errors, and terminate the link.
      Other optional facilities provided are authentication of the
      identity of its peer on the link, and determination when a link is
      functioning properly and when it is failing.

   PPTP (Point-to-Point Tunneling Protocol)

      A protocol that allows PPP to be tunneled through an IP network
      [RFC2637].

   VPN (Virtual Private Network)

      In this document, this term is used to describe access services
      that use tunneling methods.

1.3.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

   The use of "MUST" and "MUST NOT" in the AVP Flag Rules columns of AVP
   Tables in this document refers to AVP flags ([RFC6733], Section 4.1)
   that:

   o  MUST be set to 1 in the AVP Header ("MUST" column) and

   o  MUST NOT be set to 1 ("MUST NOT" column)

1.4.  Advertising Application Support

   Diameter nodes conforming to this specification MUST advertise
   support by including the value of one (1) in the Auth-Application-Id
   of the Capabilities-Exchange-Request (CER) message [RFC6733].

1.5.  Application Identification

   When used in this application, the Auth-Application-Id AVP MUST be
   set to the value one (1) in the following messages

   o  AA-Request (Section 3.1)

   o  Re-Auth-Request(Section 3.3)

   o  Session-Termination-Request (Section 3.5)

   o  Abort-Session-Request (Section 3.7)

1.6.  Accounting Model

   It is RECOMMENDED that the coupled accounting model (RFC 6733,
   Section 9.3) be used with this application; therefore, the value of
   the Acct-Application-Id AVP in the Accounting-Request (Section 3.9)
   and Accounting-Answer (Section 3.10) messages SHOULD be set to one
   (1).

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 Application 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.

   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.

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 [RFC6733].  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 [RFC6733] 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.

   A Diameter server informs the NAS of the maximum time allowed before
   reauthentication or reauthorization via the Authorization-Lifetime
   AVP [RFC6733].  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 [RFC6733]) to the NAS.  Upon receipt of
   such a message, the NAS MUST respond to the request with a Re-Auth-
   Answer (RAA) message [RFC6733].

   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
   subsessions.  A service may also use a different Session-Id value for
   accounting (see Section 9.6 of [RFC6733]).

   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., an LCP Terminate-Request message
   [RFC1661] is received) or an administrative command, the NAS MUST
   issue a Session-Termination-Request (STR) [RFC6733] 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)
   [RFC6733] MUST issue an Abort-Session-Answer (ASA) if the session
   identified is active and disconnect the PPP (or tunneling) session.

   If accounting is active, an Accounting STOP_RECORD message [RFC6733]
   MUST be sent upon termination of the session context.

   More information on Diameter Session Termination can be found in
   Sections 8.4 and 8.5 of [RFC6733].

3.  Diameter NAS Application Messages

   This section defines the Diameter message Command Code [RFC6733]
   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  | Section 3.1  |
   | AA-Answer                         |   AAA   | 265  | Section 3.2  |
   | Re-Auth-Request                   |   RAR   | 258  | Section 3.3  |
   | Re-Auth-Answer                    |   RAA   | 258  | Section 3.4  |
   | Session-Termination-Request       |   STR   | 275  | Section 3.5  |
   | Session-Termination-Answer        |   STA   | 275  | Section 3.6  |
   | Abort-Session-Request             |   ASR   | 274  | Section 3.7  |
   | Abort-Session-Answer              |   ASA   | 274  | Section 3.8  |
   | Accounting-Request                |   ACR   | 271  | Section 3.9  |
   | Accounting-Answer                 |   ACA   | 271  | Section 3.10 |
   +-----------------------------------+---------+------+--------------+

   Note that the message formats in the following subsections use the
   standard Diameter Command Code Format ([RFC6733], Section 3.2).

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
   [RFC6733].  The recommended value for most 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 4.4.

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

   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 ]
                        * [ 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 4.4.

   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 can be achieved in PPP via PAP.  If it is impossible to
   deliver the text prompt to the user, the Diameter NAS Application
   client 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 ]
                         [ 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 ]
                         [ 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 can initiate reauthentication and/or
   reauthorization for a particular session by issuing a Re-Auth-Request
   (RAR) message [RFC6733].

   For example, for prepaid 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 reauthentication 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 ]
                          [ 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 [RFC6733] 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 ]

3.5.  Session-Termination-Request (STR) Command

   The Session-Termination-Request (STR) message [RFC6733] 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 [RFC6733] 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 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 ]
                        * [ Failed-AVP ]
                          [ Origin-AAA-Protocol ]
                          [ Origin-State-Id ]
                        * [ Redirect-Host ]
                          [ Redirect-Host-Usage ]
                          [ Redirect-Max-Cache-Time ]
                        * [ Proxy-Info ]
                        * [ AVP ]

3.7.  Abort-Session-Request (ASR) Command

   The Abort-Session-Request (ASR) message [RFC6733] can be sent by any
   Diameter 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 ]

3.8.  Abort-Session-Answer (ASA) Command

   The ASA message [RFC6733] 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, the Result-Code is set to DIAMETER_SUCCESS.  If the
   session is not currently active, the Result-Code AVP is set to
   DIAMETER_UNKNOWN_SESSION_ID.  If the access device does not stop the
   session for any other reason, the Result-Code AVP 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 [RFC6733] is sent by the NAS to report its session
   information to a target server downstream.

   The Acct-Application-Id AVP MUST be present.

   The AVPs listed in the Diameter Base protocol specification [RFC6733]
   MUST be assumed to be present, as appropriate.  NAS service-specific
   accounting AVPs SHOULD be present as described in Section 4.6 and the
   rest of this specification.

      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 }
                         [ 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 ]
                         [ 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 [RFC6733] is used to acknowledge an Accounting-
   Request command.  The Accounting-Answer command contains the same
   Session-Id as the Request.

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

   The Acct-Application-Id AVP MUST be present.

   The AVPs listed in the Diameter Base protocol specification [RFC6733]
   MUST be assumed to be present, as appropriate.  NAS service-specific
   accounting AVPs SHOULD be present as described in Section 4.6 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 }
                         [ 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 ]
                       * [ AVP ]

4.  Diameter NAS Application AVPs

   The following sections define a new derived AVP data format, define a
   set of application-specific AVPs, and describe the use of AVPs
   defined in other documents by the Diameter NAS Application.

4.1.  Derived AVP Data Formats

4.1.1.  QoSFilterRule

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

   o  Direction (in or out)

   o  Source and destination IP address (possibly masked)

   o  Protocol

   o  Source and destination port (lists or ranges)

   o  Differentiated Services Code Point (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 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]

      where

      action

                  tag  Mark packet with a specific DSCP [RFC2474]

                  meter  Meter traffic

      dir         The format is as described under IPFilterRule
                  [RFC6733]

      proto       The format is as described under IPFilterRule
                  [RFC6733]

      src and dst The format is as described under IPFilterRule
                  [RFC6733]

   The options are described in Section 4.4.9.

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

4.2.  NAS Session AVPs

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

4.2.1.  Call and Session Information

   This section describes the AVPs specific to 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 following AVPs from the
   Diameter Base protocol specification [RFC6733]:

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

   The following table gives the possible flag values for the session
   level AVPs.

                                            +-----------+
                                            | AVP Flag |
                                            |   Rules  |
                                            |-----+-----+
                                            |MUST | MUST|
   Attribute Name          Section Defined  |     |  NOT|
   -----------------------------------------|-----+-----|
   NAS-Port                4.2.2            |  M  |  V  |
   NAS-Port-Id             4.2.3            |  M  |  V  |
   NAS-Port-Type           4.2.4            |  M  |  V  |
   Called-Station-Id       4.2.5            |  M  |  V  |
   Calling-Station-Id      4.2.6            |  M  |  V  |
   Connect-Info            4.2.7            |  M  |  V  |
   Originating-Line-Info   4.2.8            |  M  |  V  |
   Reply-Message           4.2.9            |  M  |  V  |
   -----------------------------------------|-----+-----|

4.2.2.  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 authenticates the
   user.  Note that "port" is meant in its sense as a service connection
   on the NAS, not as an IP protocol identifier; hence, the format and
   contents of the string that identifies the port are specific to the
   NAS implementation.

   Either the NAS-Port AVP or the NAS-Port-Id AVP (Section 4.2.3) SHOULD
   be present in the AA-Request (AAR, Section 3.1) command if the NAS
   differentiates among its ports.

4.2.3.  NAS-Port-Id AVP

   The NAS-Port-Id AVP (AVP Code 87) is of type UTF8String and consists
   of 7-bit US-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 the NAS-Port-Id AVP or the NAS-Port AVP (Section 4.2.2) SHOULD
   be present in the AA-Request (AAR, Section 3.1) command if the NAS
   differentiates among its ports.  NAS-Port-Id is intended for use by
   NASes that cannot conveniently number their ports.

4.2.4.  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 currently supported values of the NAS-Port-Type AVP are listed in
   [RADIUSAttrVals].

4.2.5.  Called-Station-Id AVP

   The Called-Station-Id AVP (AVP Code 30) is of type UTF8String and
   contains a 7-bit US-ASCII string sent by the NAS to describe the
   Layer 2 address the user contacted in the request.  For dialup
   access, this can be a phone number obtained by using the Dialed
   Number Identification Service (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 Media Access Control (MAC) address formatted as described in
   [RFC3580].

   If the Called-Station-Id AVP is present in an AAR message, the Auth-
   Request-Type AVP is set to AUTHORIZE_ONLY, and the User-Name AVP is
   absent, the Diameter server MAY perform authorization based on this
   AVP.  This can be used by a NAS to request whether a call should be
   answered based on the DNIS result.

   Further codification of this field's allowed content and usage is
   outside the scope of this specification.

4.2.6.  Calling-Station-Id AVP

   The Calling-Station-Id AVP (AVP Code 31) is of type UTF8String and
   contains a 7-bit US-ASCII string sent by the NAS to describe 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, formatted as described in RFC 3580.

   If the Calling-Station-Id AVP is present in an AAR message, the Auth-
   Request-Type AVP is set to AUTHORIZE_ONLY, and the User-Name AVP is
   absent, the Diameter server MAY perform authorization based on the
   value of this AVP.  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.)

   Further codification of this field's allowed content and usage is
   outside the scope of this specification.

4.2.7.  Connect-Info AVP

   The Connect-Info AVP (AVP Code 77) is of type UTF8String and is sent
   in the AA-Request message or an ACR message with the value of the
   Accounting-Record-Type AVP set to STOP.  When sent in the AA-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 at which the NAS modem transmits), then a
   slash (/), then the receive speed, and then other optional
   information.

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

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

4.2.8.  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 a Signaling System 7 (SS7).

   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 phone, cellular phone).  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 information on the currently assigned
   values, see [ANITypes].

4.2.9.  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 contain text to prompt the user before
   another AA-Request attempt.  When used in an AA-Answer message
   containing a Result-Code AVP with the value DIAMETER_MULTI_ROUND_AUTH
   or in a Re-Auth-Request message, it MAY contain text to prompt the
   user for a response.

4.3.  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 Authentication, Authorization, and Accounting
   service [RFC2865] over a more reliable and secure transport, as
   defined in the Diameter Base protocol [RFC6733].

   The following table gives the possible flag values for the session
   level AVPs.

                                            +----------+
                                            | AVP Flag |
                                            |  Rules   |
                                            |----+-----|
                                            |MUST| MUST|
   Attribute Name           Section Defined |    |  NOT|
   -----------------------------------------|----+-----|
   User-Password                 4.3.1      | M  |  V  |
   Password-Retry                4.3.2      | M  |  V  |
   Prompt                        4.3.3      | M  |  V  |
   CHAP-Auth                     4.3.4      | M  |  V  |
   CHAP-Algorithm                4.3.5      | M  |  V  |
   CHAP-Ident                    4.3.6      | M  |  V  |
   CHAP-Response                 4.3.7      | M  |  V  |
   CHAP-Challenge                4.3.8      | M  |  V  |
   ARAP-Password                 4.3.9      | M  |  V  |
   ARAP-Challenge-Response       4.3.10     | M  |  V  |
   ARAP-Security                 4.3.11     | M  |  V  |
   ARAP-Security-Data            4.3.12     | M  |  V  |
   -----------------------------------------|----+-----|

4.3.1.  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 by the
   Diameter Base protocol [RFC6733], Diameter messages are encrypted by
   using IPsec [RFC4301] or Transport Layer Security (TLS) [RFC5246].
   Unless this AVP is used for one-time passwords, the User-Password AVP
   SHOULD NOT be used in untrusted proxy environments without encrypting
   it by using end-to-end security techniques.

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

4.3.2.  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 (Section 4.4.10.1) is set to ARAP.

4.3.3.  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 [RADIUSAttrVals].

4.3.4.  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) [RFC1994].  If the CHAP-Auth
   AVP is found in a message, the CHAP-Challenge AVP (Section 4.3.8)
   MUST be present as well.  The optional AVPs containing the CHAP
   response depend upon the value of the CHAP-Algorithm AVP
   (Section 4.3.8).  The grouped AVP has the following ABNF [RFC5234]
   grammar:

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

4.3.5.  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 [RFC1994].  The following values are currently supported:

   CHAP with MD5       5

      The CHAP response is computed by using the procedure described in
      [RFC1994].  This algorithm requires that the CHAP-Response AVP
      (Section 4.3.7) MUST be present in the CHAP-Auth AVP
      (Section 4.3.4).

4.3.6.  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 [RFC1994].

4.3.7.  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 [RFC1994].

4.3.8.  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
   [RFC1994].

4.3.9.  ARAP-Password AVP

   The ARAP-Password AVP (AVP Code 70) is of type OctetString and is
   only present when the Framed-Protocol AVP (Section 4.4.10.1) 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 [RFC2869] for more information on the contents of this AVP.

4.3.10.  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 (Section 4.4.10.1)
   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 Diameter
   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
   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.

4.3.11.  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
   (Section 4.4.10.1) is set to the value of ARAP, and the Result-Code
   AVP ([RFC6733], Section 7.1) is set to DIAMETER_MULTI_ROUND_AUTH.
   See RFC 2869 for more information on the contents of this AVP.

4.3.12.  ARAP-Security-Data AVP

   The ARAP-Security-Data 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 (Section 4.4.10.1) is set to the value of ARAP and the
   Result-Code AVP ([RFC6733], Section 7.1) is set to
   DIAMETER_MULTI_ROUND_AUTH.  This AVP contains the security module
   challenge or response associated with the ARAP Security Module
   specified in the ARAP-Security AVP (Section 4.3.11).

4.4.  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
   Section 4.5 MAY be present.

   The following table gives the possible flag values for the session-
   level AVPs.

                                            +----------+
                                            | AVP Flag |
                                            |  Rules   |
                                            |----+-----|
                                            |MUST| MUST|
   Attribute Name           Section Defined |    |  NOT|
   -----------------------------------------|----+-----|
   Service-Type                4.4.1        | M  |  V  |
   Callback-Number             4.4.2        | M  |  V  |
   Callback-Id                 4.4.3        | M  |  V  |
   Idle-Timeout                4.4.4        | M  |  V  |
   Port-Limit                  4.4.5        | M  |  V  |
   NAS-Filter-Rule             4.4.6        | M  |  V  |
   Filter-Id                   4.4.7        | M  |  V  |
   Configuration-Token         4.4.8        | M  |  V  |
   QoS-Filter-Rule             4.4.9        |    |     |
   Framed-Protocol             4.4.10.1     | M  |  V  |
   Framed-Routing              4.4.10.2     | M  |  V  |
   Framed-MTU                  4.4.10.3     | M  |  V  |
   Framed-Compression          4.4.10.4     | M  |  V  |
   Framed-IP-Address           4.4.10.5.1   | M  |  V  |
   Framed-IP-Netmask           4.4.10.5.2   | M  |  V  |
   Framed-Route                4.4.10.5.3   | M  |  V  |
   Framed-Pool                 4.4.10.5.4   | M  |  V  |
   Framed-Interface-Id         4.4.10.5.5   | M  |  V  |
   Framed-IPv6-Prefix          4.4.10.5.6   | M  |  V  |
   Framed-IPv6-Route           4.4.10.5.7   | M  |  V  |
   Framed-IPv6-Pool            4.4.10.5.8   | M  |  V  |
   Framed-IPX-Network          4.4.10.6.1   | M  |  V  |
   Framed-Appletalk-Link       4.4.10.7.1   | M  |  V  |
   Framed-Appletalk-Network    4.4.10.7.2   | M  |  V  |
   Framed-Appletalk-Zone       4.4.10.7.3   | M  |  V  |
   ARAP-Features               4.4.10.8.1   | M  |  V  |
   ARAP-Zone-Access            4.4.10.8.2   | M  |  V  |
   Login-IP-Host               4.4.11.1     | M  |  V  |
   Login-IPv6-Host             4.4.11.2     | M  |  V  |
   Login-Service               4.4.11.3     | M  |  V  |
   Login-TCP-Port              4.4.11.4.1   | M  |  V  |
   Login-LAT-Service           4.4.11.5.1   | M  |  V  |
   Login-LAT-Node              4.4.11.5.2   | M  |  V  |
   Login-LAT-Group             4.4.11.5.3   | M  |  V  |
   Login-LAT-Port              4.4.11.5.4   | M  |  V  |
   -----------------------------------------|----+-----|

4.4.1.  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-Type AVPs 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
   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 complete list of defined values that the Service-Type AVP can
   take can be found in [RFC2865] and the relevant IANA registry
   [RADIUSAttrVals], but the following values require further
   qualification here:

      Login (1)

         The user should be connected to a host.  The message MAY
         include additional AVPs as defined in Sections 4.4.11.4 or
         4.4.11.5.

      Framed (2)

         A Framed Protocol, such as PPP or SLIP, should be started for
         the user.  The message MAY include additional AVPs defined in
         Sections 4.4.10 or 4.5 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
         Sections 4.4.10 or 4.5 for tunneling services.

4.4.2.  Callback-Number AVP

   The Callback-Number AVP (AVP Code 19) is of type UTF8String and
   contains a dialing string to be used for callback, the format of
   which is deployment specific.  The Callback-Number AVP 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.

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

4.4.3.  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
   (Section 4.4.2) is therefore RECOMMENDED.

4.4.4.  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.

4.4.5.  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 [RFC1990] service is desired, but the
   server is not required to honor the hint in the corresponding
   response.

4.4.6.  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.

4.4.7.  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.  It is intended to be
   human readable.  Zero or more Filter-Id AVPs MAY be sent in an
   authorization answer message.

   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 environments where backward compatibility with RADIUS is not
   required, it is RECOMMENDED that the NAS-Filter-Rule AVP
   (Section 4.4.6) be used instead.

4.4.8.  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 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.

4.4.9.  QoS-Filter-Rule AVP

   The QoS-Filter-Rule AVP (AVP Code 407) is of type QoSFilterRule
   (Section 4.1.1) 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.

   The use of this AVP is NOT RECOMMENDED; the AVPs defined by [RFC5777]
   SHOULD be used instead.

   The following options are defined for the QoSFilterRule filters:

   DSCP <color>

         If action is set to tag (Section 4.1.1), this option MUST be
         included in the rule.

         Color values are defined in [RFC2474].  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
         [RFC2597].  and MUST be present if the action is set to meter
         (Section 4.1.1) 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 [RFC2597] (e.g., AF13).

         The metering option also supports the strict limit on traffic
         required by Expedited Forwarding, as defined in [RFC3246].  The
         color_over option may contain the keyword "drop" to prevent
         forwarding of traffic that exceeds the rate parameter.

4.4.10.  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".

4.4.10.1.  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 [RADIUSAttrVals].

4.4.10.2.  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 [RADIUSAttrVals].

4.4.10.3.  Framed-MTU AVP

   The Framed-MTU AVP (AVP Code 12) is of type Unsigned32 and contains
   the Maximum Transmission Unit (MTU) 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.

4.4.10.4.  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 [RADIUSAttrVals].

4.4.10.5.  IP Access Authorization AVPs

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

4.4.10.5.1.  Framed-IP-Address AVP

   The Framed-IP-Address AVP (AVP Code 8) [RFC2865] 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).

4.4.10.5.2.  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

   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.

4.4.10.5.3.  Framed-Route AVP

   The Framed-Route AVP (AVP Code 22) is of type UTF8String and contains
   the 7-bit US-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,

      "192.0.2.0/24 192.0.2.1 1"

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

      "192.0.2.0 192.0.2.1 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.

4.4.10.5.4.  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
   [RFC2869], the encoding of the Data field SHOULD also conform to the
   rules for the UTF8String Data Format.

4.4.10.5.5.  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 identifier is desired, but the server is not
   required to honor the hint in the corresponding response.

4.4.10.5.6.  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.

4.4.10.5.7.  Framed-IPv6-Route AVP

   The Framed-IPv6-Route AVP (AVP Code 99) is of type UTF8String and
   contains the US-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,

      "2001:db8::/32 2001:db8:106: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:

      "2001:db8::/32 :: 1"

4.4.10.5.8.  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
   [RFC3162], the encoding of the Data field SHOULD also conform to the
   rules for the UTF8String Data Format.

4.4.10.6.  IPX Access AVPs

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

4.4.10.6.1.  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).

4.4.10.7.  AppleTalk Network Access AVPs

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

4.4.10.7.1.  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.

4.4.10.7.2.  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.

4.4.10.7.3.  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.

4.4.10.8.  AppleTalk Remote Access AVPs

   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 (Section 4.4.10.1) is set to ARAP.  Section 2.2 of RFC
   2869 describes the operational use of these attributes.

4.4.10.8.1.  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 RFC 2869 for more information about the
   format of this AVP.

4.4.10.8.2.  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 [RADIUSAttrVals] and defined in
   [RFC2869].

4.4.11.  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".

4.4.11.1.  Login-IP-Host AVP

   The Login-IP-Host AVP (AVP Code 14) [RFC2865] 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
   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.

4.4.11.2.  Login-IPv6-Host AVP

   The Login-IPv6-Host AVP (AVP Code 98) [RFC3162] 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.

4.4.11.3.  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 RFC 2869.

4.4.11.4.  TCP Services

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

4.4.11.4.1.  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.

4.4.11.5.  LAT Services

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

4.4.11.5.1.  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.  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 lower-case
   alphabetics, and the ISO Latin-1 character set extension
   [ISO.8859-1.1987].  All LAT string comparisons are case insensitive.

4.4.11.5.2.  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 lower-case
   alphabetics, and the ISO Latin-1 character set extension
   [ISO.8859-1.1987].  All LAT string comparisons are case insensitive.

4.4.11.5.3.  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.

4.4.11.5.4.  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.

   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
   [ISO.8859-1.1987].

   All LAT string comparisons are case insensitive.

4.5.  NAS Tunneling AVPs

   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 Authentication, Authorization, and Accounting server, based on
   the user's authorization information.  Several tunnel characteristics
   may be returned, and the NAS implementation may choose one.  See
   [RFC2868] and [RFC2867] for further information.

   The following table gives the possible flag values for the session-
   level AVPs and specifies whether the AVP MAY be encrypted.

                                            +----------+
                                            | AVP Flag |
                                            |  Rules   |
                                            |----+-----|
                                            |MUST| MUST|
   Attribute Name          Section Defined  |    | NOT |
   -----------------------------------------|----+-----|
   Tunneling                   4.5.1        | M  |  V  |
   Tunnel-Type                 4.5.2        | M  |  V  |
   Tunnel-Medium-Type          4.5.3        | M  |  V  |
   Tunnel-Client-Endpoint      4.5.4        | M  |  V  |
   Tunnel-Server-Endpoint      4.5.5        | M  |  V  |
   Tunnel-Password             4.5.6        | M  |  V  |
   Tunnel-Private-Group-Id     4.5.7        | M  |  V  |
   Tunnel-Assignment-Id        4.5.8        | M  |  V  |
   Tunnel-Preference           4.5.9        | M  |  V  |
   Tunnel-Client-Auth-Id       4.5.10       | M  |  V  |
   Tunnel-Server-Auth-Id       4.5.11       | M  |  V  |
   -----------------------------------------|----+-----|

4.5.1.  Tunneling AVP

   The Tunneling AVP (AVP Code 401) is of type Grouped and contains the
   following AVPs, used to describe a compulsory tunnel service
   [RFC2868] [RFC2867].  Its data field has the following ABNF grammar:

   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 ]

4.5.2.  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 ACR 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 [RADIUSAttrVals].

4.5.3.  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 [RFC3931]) 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 [RADIUSAttrVals].

4.5.4.  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 ACR messages, in which case it indicates the
   address from which the tunnel was initiated.  This AVP, along with
   the Tunnel-Server-Endpoint (Section 4.5.5) and Session-Id AVPs
   ([RFC6733], Section 8.8), can be used to provide a globally unique
   means to identify a tunnel for accounting and auditing purposes.

   If the value of the Tunnel-Medium-Type AVP (Section 4.5.3) is IPv4
   (1), then this string is either the fully qualified domain name
   (FQDN) of the tunnel client 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 client machine or a text representation of the
   address in either the preferred or alternate form [RFC3516].
   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.

   Note that this application handles Internationalized Domain Names
   (IDNs) in the same way as the Diameter Base protocol (see Appendix D
   of RFC 6733 for details).

4.5.5.  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 ACR messages, in
   which case it indicates the address from which the tunnel was
   initiated.  This AVP, along with the Tunnel-Client-Endpoint
   (Section 4.5.4) and Session-Id AVP ([RFC6733], Section 8.8), can 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 [RFC3516].
   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.

   Note that this application handles IDNs in the same way as the
   Diameter base protocol (see Appendix D of RFC 6733 for details).

4.5.6.  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 SHOULD NOT be used in untrusted proxy
   environments without encrypting it by using end-to-end security
   techniques.

4.5.7.  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 ACR messages that pertain to the tunneled session.

4.5.8.  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 [RFC2637] and L2TP [RFC3931], 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 (for example, a 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 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:

   o  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.

   o  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.

   o  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.

4.5.9.  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 AVPs.  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.

   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.

4.5.10.  Tunnel-Client-Auth-Id AVP

   The Tunnel-Client-Auth-Id AVP (AVP Code 90) is of type UTF8String and
   specifies the 7-bit US-ASCII 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 ACR messages
   pertaining to the tunneled session.

4.5.11.  Tunnel-Server-Auth-Id AVP

   The Tunnel-Server-Auth-Id AVP (AVP Code 91) is of type UTF8String and
   specifies the 7-bit US-ASCII 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 ACR
   messages pertaining to the tunneled session.

4.6.  NAS Accounting AVPs

   Applications implementing this specification use Diameter Accounting
   (as defined in [RFC6733]) and the AVPs in the following section.
   Service-specific AVP usage is defined in the tables in Section 5.

   If accounting is active, Accounting Request (ACR) messages SHOULD be
   sent after the completion of any Authentication or Authorization
   transaction and at the end of a session.  The value of the
   Accounting-Record-Type AVP [RFC6733] 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 latter 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 gives the possible flag values for the session-
   level AVPs and specifies whether the AVP MAY be encrypted.

                                            +----------+
                                            | AVP Flag |
                                            |  Rules   |
                                            |----+-----|
                                    Section |MUST| MUST|
   Attribute Name                   Defined |    |  NOT|
   -----------------------------------------|----+-----|
   Accounting-Input-Octets           4.6.1  | M  |  V  |
   Accounting-Output-Octets          4.6.2  | M  |  V  |
   Accounting-Input-Packets          4.6.3  | M  |  V  |
   Accounting-Output-Packets         4.6.4  | M  |  V  |
   Acct-Session-Time                 4.6.5  | M  |  V  |
   Acct-Authentic                    4.6.6  | M  |  V  |
   Accounting-Auth-Method            4.6.7  | M  |  V  |
   Acct-Delay-Time                   4.6.8  | M  |  V  |
   Acct-Link-Count                   4.6.9  | M  |  V  |
   Acct-Tunnel-Connection            4.6.10 | M  |  V  |
   Acct-Tunnel-Packets-Lost          4.6.11 | M  |  V  |
   -----------------------------------------|----+-----|

4.6.1.  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.

   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 [RFC6733] of
   INTERIM_RECORD or STOP_RECORD.

4.6.2.  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.

4.6.3.  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.

4.6.4.  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.

4.6.5.  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.

4.6.6.  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 [RADIUSAttrVals].

4.6.7.  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
   AVP is semantically equivalent, and the supported values are
   identical, to the Microsoft MS-Acct-Auth-Type vendor-specific RADIUS
   attribute [RFC2548]).

4.6.8.  Acct-Delay-Time AVP

   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
   it 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 re-sent 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.

4.6.9.  Acct-Link-Count AVP

   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-Request
   AVPs 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-Request AVPs
   received with Accounting-Record-Type = STOP_RECORD and with the same
   Acct-Multi-Session-Id and unique Session-Id AVPs equals the largest
   value of Acct-Link-Count seen in those Accounting-Request AVPs, all
   STOP_RECORD Accounting-Request AVPs for that multilink service have
   been received.

   The following example, showing eight Accounting-Request AVPs,
   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
   AVPs.

   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

4.6.10.  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 (Section 4.5.4) and
   Tunnel-Server-Endpoint (Section 4.5.5) 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 (Section 4.5.2).  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.

4.6.11.  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 tunnel.

5.  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.  Messages and AVPs defined in the Diameter Base protocol
   [RFC6733] 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 tables use 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    Exactly one instance of the AVP MUST be present in the
           message.

5.1.  AA-Request / AA-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 |
   ------------------------------|-----+-----+

                                 +-----------+
                                 |  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 |
   ------------------------------|-----+-----+

                                 +-----------+
                                 |  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   |
   ------------------------------|-----+-----+

5.2.  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 [RFC6733] and [RFC2866].

5.2.1.  Framed Access Accounting AVP Table

   The table in this section is used when the Service-Type AVP
   (Section 4.4.1) 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+  |
      ---------------------------------------|-----+-----+

                                          +-----------+
                                          |  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 |
   ---------------------------------------|-----+-----+

5.2.2.  Non-Framed Access Accounting AVP Table

   The table in this section is used when the Service-Type AVP
   (Section 4.4.1) 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   |
   ---------------------------------------|-----+-----+

                                          +-----------+
                                          |  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 |
   ---------------------------------------|-----+-----+

6.  Unicode Considerations

   A number of the AVPs in this RFC use the UTF8String type specified in
   the Diameter Base protocol [RFC6733].  Implementation differences in
   Unicode input processing may result in the same Unicode input
   characters generating different UTF-8 strings that fail to match when
   compared for equality.  This may result in interoperability problems
   between a network access server and a Diameter server when a UTF-8
   string entered locally is compared with one received via Diameter.
   Many of the uses of UTF8String in this RFC are limited to the 7-bit
   US-ASCII-compatible subset of UTF-8, where this class of Unicode
   string comparison problems does not arise.

   Careful preparation of Unicode strings can increase the likelihood
   that string comparison will work in ways that make sense for typical
   users throughout the world; [RFC3454] is an example a framework for
   such Unicode string preparation.  The Diameter application specified
   in this RFC has been deployed with use of Unicode in accordance with
   [RFC4005], which does not require any Unicode string preparation.  As
   a result, additional requirements for Unicode string preparation in
   this RFC would not be backwards compatible with existing usage.

   The Diameter server and the network access servers that it serves can
   be assumed to be under common administrative control, and all of the
   UTF-8 strings involved are part of the configuration of these
   servers.  Therefore, administrative interfaces for implementations of
   this RFC:

   a.  SHOULD accept direct UTF-8 input of all configuration strings for
       AVPs that allow Unicode characters beyond the 7-bit US-ASCII-
       compatible subset of Unicode (in addition to any provisions for
       accepting Unicode characters for processing into UTF-8), and

   b.  SHOULD make all such configuration strings available as UTF-8
       strings.

   This functionality enables an administrator who encounters Unicode
   string comparison problems to copy one instance of aproblematic UTF-8
   string from one server to the other, after which the two (now
   identical) copies should compare as expected.

7.  IANA Considerations

   Several of the namespaces used in this document are managed by the
   Internet Assigned Numbers Authority [IANA], including the AVP Codes
   [AVP-Codes], AVP Specific Values [AVP-Vals], Application IDs
   [App-Ids], Command Codes [Command-Codes], and RADIUS Attribute Values
   [RADIUSAttrVals].

   For the current values allocated, and the policies governing
   allocation in those namespaces, please see the above-referenced
   registries.

8.  Security Considerations

   This document describes the extension of Diameter for the NAS
   application.  Security considerations regarding the Diameter protocol
   itself are discussed in [RFC6733].  Use of this application of
   Diameter MUST take into consideration the security issues and
   requirements of the Base protocol.

8.1.  Authentication Considerations

   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 [RFC4072] can offer
   better security, given a method suitable for the circumstances.

   Depending on the value of 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 provided by RADIUS (Section 5.6 of
   [RFC2865]) in that no access decision is requested.  As a result, a
   new session cannot be started as a result of a response to an
   authorization-only request without introducing a significant security
   vulnerability.

8.2.  AVP Considerations

   Diameter AVPs often contain security-sensitive data; for example,
   user passwords and location data, network addresses and cryptographic
   keys.  With the exception of the Configuration-Token (Section 4.4.8),
   QoS-Filter-Rule (Section 4.4.9), and Tunneling (Section 4.5.1) AVPs,
   all of the AVPs defined in this document are considered to be
   security-sensitive.

   Diameter messages containing any AVPs considered to be security-
   sensitive MUST only be sent protected via mutually authenticated TLS
   or IPsec.  In addition, those messages MUST NOT be sent via
   intermediate nodes unless there is end-to-end security between the
   originator and recipient or the originator has locally trusted
   configuration that indicates that end-to-end security is not needed.
   For example, end-to-end security may not be required in the case
   where an intermediary node is known to be operated as part of the
   same administrative domain as the endpoints so that an ability to
   successfully compromise the intermediary would imply a high
   probability of being able to compromise the endpoints as well.  Note
   that no end-to-end security mechanism is specified in this document.

9.  References

9.1.  Normative References

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

   [RFC1994]  Simpson, W., "PPP Challenge Handshake Authentication
              Protocol (CHAP)", RFC 1994, August 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)", RFC
              2865, June 2000.

   [RFC3162]  Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6", RFC
              3162, August 2001.

   [RFC3516]  Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516,
              April 2003.

   [RFC3539]  Aboba, B. and J. Wood, "Authentication, Authorization and
              Accounting (AAA) Transport Profile", RFC 3539, June 2003.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC5777]  Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M.,
              and A. Lior, "Traffic Classification and Quality of
              Service (QoS) Attributes for Diameter", RFC 5777, February
              2010.

   [RFC6733]  Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,
              "Diameter Base Protocol", RFC 6733, October 2012.

9.2.  Informative References

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

   [AVP-Codes]
              IANA, "AVP Codes",
              <http://www.iana.org/assignments/aaa-parameters/>.

   [AVP-Vals] IANA, "AVP Specific Values",
              <http://www.iana.org/assignments/aaa-parameters/>.

   [App-Ids]  IANA, "Application IDs",
              <http://www.iana.org/assignments/aaa-parameters/>.

   [AppleTalk]
              Sidhu, G., Andrews, R., and A. Oppenheimer, "Inside
              AppleTalk", Second Edition Apple Computer, 1990.

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

   [Command-Codes]
              IANA, "Command Codes",
              <http://www.iana.org/assignments/aaa-parameters/>.

   [IANA]     IANA, "Internet Assigned Numbers Authority",
              <http://www.iana.org/>.

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

   [ISO.8859-1.1987]
              International Organization for Standardization,
              "Information technology - 8-bit single byte coded graphic
              - character sets - Part 1: Latin alphabet No. 1, JTC1/
              SC2", ISO Standard 8859-1, 1987.

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

   [RADIUSAttrVals]
              IANA, "Radius Attribute Values",
              <http://www.iana.org/assignments/radius-types/>.

   [RFC1334]  Lloyd, B. and W. Simpson, "PPP Authentication Protocols",
              RFC 1334, October 1992.

   [RFC1661]  Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
              RFC 1661, July 1994.

   [RFC1990]  Sklower, K., Lloyd, B., McGregor, G., Carr, D., and T.
              Coradetti, "The PPP Multilink Protocol (MP)", RFC 1990,
              August 1996.

   [RFC2474]  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.

   [RFC2548]  Zorn, G., "Microsoft Vendor-specific RADIUS Attributes",
              RFC 2548, March 1999.

   [RFC2597]  Heinanen, J., Baker, F., Weiss, W., and J. Wroclawski,
              "Assured Forwarding PHB Group", RFC 2597, June 1999.

   [RFC2637]  Hamzeh, K., Pall, G., Verthein, W., Taarud, J., Little,
              W., and G. Zorn, "Point-to-Point Tunneling Protocol", RFC
              2637, July 1999.

   [RFC2866]  Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.

   [RFC2867]  Zorn, G., Aboba, B., and D. Mitton, "RADIUS Accounting
              Modifications for Tunnel Protocol Support", RFC 2867, June
              2000.

   [RFC2868]  Zorn, G., Leifer, D., Rubens, A., Shriver, J., Holdrege,
              M., and I. Goyret, "RADIUS Attributes for Tunnel Protocol
              Support", RFC 2868, June 2000.

   [RFC2869]  Rigney, C., Willats, W., and P. Calhoun, "RADIUS
              Extensions", RFC 2869, June 2000.

   [RFC2881]  Mitton, D. and M. Beadles, "Network Access Server
              Requirements Next Generation (NASREQNG) NAS Model", RFC
              2881, July 2000.

   [RFC2989]  Aboba, B., Calhoun, P., Glass, S., Hiller, T., McCann, P.,
              Shiino, H., Walsh, P., Zorn, G., Dommety, G., Perkins, C.,
              Patil, B., Mitton, D., Manning, S., Beadles, M., Chen, X.,
              Sivalingham, S., Hameed, A., Munson, M., Jacobs, S., Lim,
              B., Hirschman, B., Hsu, R., Koo, H., Lipford, M.,
              Campbell, E., Xu, Y., Baba, S., and E. Jaques, "Criteria
              for Evaluating AAA Protocols for Network Access", RFC
              2989, November 2000.

   [RFC3169]  Beadles, M. and D. Mitton, "Criteria for Evaluating
              Network Access Server Protocols", RFC 3169, September
              2001.

   [RFC3246]  Davie, B., Charny, A., Bennet, J., 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.

   [RFC3454]  Hoffman, P. and M. Blanchet, "Preparation of
              Internationalized Strings ("stringprep")", RFC 3454,
              December 2002.

   [RFC3580]  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.

   [RFC3931]  Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
              Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.

   [RFC4005]  Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
              "Diameter Network Access Server Application", RFC 4005,
              August 2005.

   [RFC4072]  Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible
              Authentication Protocol (EAP) Application", RFC 4072,
              August 2005.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, December 2005.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

Appendix A.  Acknowledgements

A.1.  This Document

   The vast majority of the text in this document was taken directly
   from RFC 4005; the editor owes a debt of gratitude to the authors
   thereof (especially Dave Mitton, who somehow managed to make nroff
   paginate the AVP Occurance Tables correctly!).

   Thanks (in no particular order) to Jai-Jin Lim, Liu Hans, Sebastien
   Decugis, Jouni Korhonen, Mark Jones, Hannes Tschofenig, Dave Crocker,
   David Black, Barry Leiba, Peter Saint-Andre, Stefan Winter, and
   Lionel Morand for their useful reviews and helpful comments.

A.2.  RFC 4005

   The authors would like to thank Carl Rigney, Allan C. Rubens, William
   Allen Simpson, and Steve Willens for their work on the original
   RADIUS protocol, from which many of the concepts in this
   specification were derived.  Thanks, also, to Carl Rigney for
   [RFC2866] and [RFC2869]; Ward Willats for [RFC2869]; Glen Zorn,
   Bernard Aboba, and Dave Mitton for [RFC2867] and [RFC3162]; and Dory
   Leifer, John Shriver, Matt Holdrege, Allan Rubens, Glen Zorn, and
   Ignacio Goyret for their work on [RFC2868].  This document stole text
   and concepts from both [RFC2868] and [RFC2869].  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.

Author's Address

   Glen Zorn (editor)
   Network Zen
   227/358 Thanon Sanphawut
   Bang Na, Bangkok  10260
   Thailand

   Phone: +66 (0)8-1000-4155
   EMail: glenzorn@gmail.com

 

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