AAA Working Group                                         Pat R. Calhoun
Internet-Draft                                    Sun Laboratories, Inc.
Category: Standards Track                             Charles E. Perkins
<draft-ietf-aaa-diameter-mobileip-03.txt>          Nokia Research Center
                                                                May 2001



                    Diameter Mobile IPv4 Extensions



Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
   and its working groups.  Note that other groups may also distribute
   working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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      http://www.ietf.org/ietf/1id-abstracts.txt

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      http://www.ietf.org/shadow.html.

   Distribution of this memo is unlimited.

   Copyright   (C) The Internet Society 2001.  All Rights Reserved.















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Abstract

   This document specifies an extension to the Diameter base protocol
   that allows a Diameter server to authenticate, authorize and collect
   accounting information for Mobile IPv4 services rendered to a mobile
   node.  Combined with the Inter-Domain capability of the base
   protocol, this extension allows mobile nodes to receive service from
   foreign service providers. The Diameter Accounting extension will be
   used by the Foreign and Home agents to transfer usage information to
   the Diameter servers.


Table of Contents

      1.0  Introduction
            1.1  Requirements language
            1.2  Inter-Domain Mobile IP
            1.3  Allocation of Home Agent in Foreign Network
            1.4  Co-located Mobile Node
            1.5  Diameter Session Termination
            1.6  Advertising extension support
      2.0  Command-Code Values
            2.1  AA-Mobile-Node-Request (AMR) Command
            2.2  AA-Mobile-Node-Answer (AMA) Command
            2.3  Home-Agent-MIP-Request (HAR) Command
            2.4  Home-Agent-MIP-Answer (HAA) Command
      3.0  Result-Code AVP Values
            3.1  Hop-by-Hop Failures
      4.0  DSI-Event AVP Values
      5.0  Diameter AVPs
            5.1  MIP-Reg-Request AVP
            5.2  MIP-Reg-Reply AVP
            5.3  MIP-Mobile-Node-Address AVP
            5.4  MIP-Home-Agent-Address AVP
            5.5  MIP-Previous-FA-FQDN AVP
            5.6  MIP-Previous-FA-Addr AVP
            5.7  MIP-Feature-Vector AVP
            5.8  MIP-MN-AAA-Auth AVP
                  5.8.1  MIP-MN-AAA-SPI AVP
                  5.8.2  MIP-Auth-Input-Data-Length AVP
                  5.8.3  MIP-Authenticator-Length AVP
                  5.8.4  MIP-Authenticator-Offset AVP
                  5.9  MIP-FA-Challenge
      6.0  Key Distribution Center
            6.1  Distributing the Mobile-Home Registration Key
            6.2  Distributing the Mobile-Foreign Registration Key
            6.3  Distributing the Foreign-Home Registration Key
            6.4  Key Distribution Example



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      7.0  Key Distribution Center (KDC) AVPs
            7.1  Mobile Node Session Keys
                  7.1.1  MIP-MN-to-FA-Key AVP
                  7.1.2  MIP-MN-to-HA-Key AVP
            7.2  Mobility Agent Session Keys
                  7.2.1  MIP-FA-to-MN-Key AVP
                  7.2.2  MIP-FA-to-HA-Key AVP
                  7.2.3  MIP-HA-to-FA-Key AVP
                  7.2.4  MIP-HA-to-MN-Key AVP
                  7.2.5  MIP-Peer-SPI AVP
                  7.2.6  MIP-Session-Key AVP
                  7.2.7  MIP-Algorithm-Type AVP
                  7.2.8  MIP-Replay-Mode AVP
            7.3  FA-MN-Preferred-SPI AVP
            7.4  FA-HA-Preferred-SPI AVP
      8.0  Accounting AVPs
            8.1  Accounting-Input-Octets AVP
            8.2  Accounting-Output-Octets AVP
            8.3  Accounting-Session-Time AVP
            8.4  Accounting-Input-Packets AVP
            8.5  Accounting-Output-Packets AVP
      9.0  Interactions with Resource Management
      10.0  AVP Table
            10.1  Mobile IP Command AVP Table
            10.2  Accounting AVP Table
      11.0  Acknowledgements
      12.0  IANA Considerations
            12.1  Command Codes
            12.2  AVP Codes
            12.3  Result-Code AVP Values
            12.4  DSI-Event AVP Values
            12.5  MIP-Feature-Vector AVP Values
            12.6  MIP-Algorithm-Type AVP Values
            12.7  MIP-Replay-Mode AVP Values
            12.8  Extension Identifier
      13.0  Security Considerations
      14.0  References
      15.0  Authors' Addresses
      16.0  Full Copyright Statement


1.0  Introduction

   Mobile IP, as defined in [4], defines a method that allows a Mobile
   Node to change its point of attachment to the Internet with minimal
   service disruption. Mobile IP does not provide any specific support
   for mobility across disparate administrative domains, and therefore
   does not specify how usage can be accounted for, which has limited



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   the applicability of Mobile IP in a IPv4 commercial deployment.  The
   Mobile IP protocol [4] requires that mobile nodes have static home
   agent and home addresses, which is not desirable in a commercial
   network.  Recent specification [8] allows a mobile node to use its
   NAI instead of its home address, which better accommodates current
   administrative practice.

   This document specifies Extension 4 to the Diameter base protocol [1]
   that allows a Diameter server to authenticate, authorize and collect
   accounting information for Mobile IPv4 services rendered to a mobile
   node. This extension MUST NOT be used in conjunction with the Mobile
   IPv6 protocol.

   Combined with the Inter-Domain capability of the base protocol, this
   extension allows  mobile nodes to receive service from foreign
   service providers. The Diameter Accounting messages will be used by
   the Foreign and Home agents to transfer usage information to the
   Diameter servers.

   The Mobile IP protocol [4] specifies a security model that requires
   that mobile nodes and home agents share a pre-existing security
   association, which leads to scaling and configuration issues. This
   specification defines Diameter functions that allow the AAA server to
   act as a Key Distribution Center (KDC), whereby dynamic registration
   keys are created and distributed to the mobility entities for the
   purposes of securing Mobile IP Registration messages.

   As with the Diameter base protocol, AAA servers implementing the
   Mobile IP extension can process users' identities supplied in a
   Network Access Identifier (NAI) format [6], which is used for
   Diameter message routing purposes.  Mobile nodes include their NAI in
   Registration messages, as defined in [8].  The use of the NAI is
   consistent with the roaming model defined by the ROAMOPS Working
   Group [7].

   The Diameter Mobile-IP Extension meets the requirements specified in
   [3, 16].  Later subsections in this introductory section provide some
   examples and message flows of the Mobile IP and Diameter messages
   that occur when a Mobile Node requests service in a foreign network.
   In this document, the role of the "attendant" [3] is performed by the
   foreign agent for the Mobile-IP Extension, and these terms will be
   used interchangeably.


1.1  Requirements language

   In this document, the key words "MAY", "MUST", "MUST NOT",
   "optional", "recommended", "SHOULD", and "SHOULD NOT", are to be



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   interpreted as described in [11].


1.2  Inter-Domain Mobile IP

   When a Mobile Node node requests service by issuing a Registration
   Request to the foreign agent, the foreign agent creates the AA-
   Mobile-Node-Request (AMR) message, which includes the AVPs defined in
   section 2.1.  The Home Address, Home Agent, Mobile Node NAI and other
   important fields are extracted from the registration messages for
   possible inclusion as Diameter AVPs.  The AMR message is then
   forwarded to the local Diameter server, known as the AAA-Foreign, or
   AAAF.

                   Visited Domain                  Home Domain
                     +--------+                     +--------+
                     |abc.com |       AMR/AMA       |xyz.com |
                     |  AAAF  |<------------------->|  AAAH  |
                  +->| server |    server-server    | server |
                  |  +--------+    communication    +--------+
                  |         ^                         ^
                  | AMR/AMA |      client-server      | HAR/HAA
                  |         |      communication      |
                  v         v                         v
          +---------+      +---------+              +---------+
          | Foreign |      | Foreign |              |  Home   |
          |  Agent  |      |  Agent  |              |  Agent  |
          +---------+      +---------+              +---------+
                            ^
                            | Mobile IP
                            |
                            v
                           +--------+
                           | Mobile |
                           | Node   | mn@xyz.com
                           +--------+
                      Figure 1: Inter-Domain Mobility

   Upon receiving the AMR, the AAAF follows the procedures outlined in
   [1] to determine whether the AMR should be processed locally, or if
   it should be forwarded to another Diameter Server, known as the AAA-
   Home, or AAAH.  Figure 1 shows an example in which a mobile node
   (mn@xyz.com) requests service from a foreign provider (abc.com).  The
   request received by the AAAF is forwarded to xyz.com's AAAH server.

   Figure 2 shows the message flows involved when the attendant (foreign
   agent) invokes the AAA infrastructure to request that a mobile node
   be authenticated and authorized.  Note that it is not required that



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   the foreign agent invoke AAA services every time a Registration
   Request is received from the mobile, but rather only when the prior
   authorization from the AAAH expires.  The expiration time of the
   authorization (and registration keys, if allocated by the AAA server)
   is communicated through the Authorization-Lifetime AVP in the AA-
   Mobile-Node-Answer (AMA, see section 2.2) from the AAAH.

   Mobile Node   Foreign Agent       AAAF          AAAH      Home Agent
   -----------   -------------   ------------   ----------   ----------
                 Advertisement &
        <--------- Challenge
   Reg-Req&MN-AAA  ---->
                      AMR------------->
                                     AMR------------>
                                                   HAR----------->
                                                     <----------HAA
                                       <-----------AMA
                        <------------AMA
        <-------Reg-Reply

              Figure 2: Mobile IP/Diameter Message Exchange

   The foreign agent (as shown in Figure 2) MAY provide a challenge,
   which gives it direct control over the replay protection in the
   Mobile IP registration process, as described in [5].  The mobile node
   includes the Challenge and MN-AAA authentication extension to enable
   authorization by AAAH.  If the authentication data supplied in the
   MN-AAA extension is invalid, AAAH returns the response (AMA) with the
   Result-Code AVP set to DIAMETER_ERROR_AUTH_FAILURE (see section 3.0).

   If the Mobile Node was successfully authenticated, the AAAH checks
   for the MIP-Home-Agent-Address AVP. If one was specified, the AAAH
   checks that the address is that of a known Home Agent, and one that
   the Mobile Node is allowed to request. If no Home Agent was
   specified, and if the MIP-Feature-Vector has the Home-Agent-Requested
   flag set, and if allowed by policy in the home domain, the AAAH
   SHOULD allocate a home agent on behalf of the Mobile Node.  This can
   be done in a variety of ways, including using a load balancing
   algorithm in order to keep the load on all home agents equal. The
   actual algorithm used and the method of discovering the home agents
   is outside the scope of this specification.

   If the AAAH does not know the address of the home agent (perhaps
   because it will be allocated by AAAF within the visited domain as
   described in section 1.3), then AAAH sends an HAR message to AAAF
   which contains a MIP-Reg-Request AVP.

   Otherwise, if the home agent address is known, the AAAH then sends a



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   Home-Agent-MIP-Request (HAR), which contains the Mobile IP
   Registration Request message data encapsulated in the MIP-Reg-Request
   AVP, to the assigned or requested Home Agent. The AAAH MAY allocate a
   home address for the mobile node, and include it in a MIP-Mobile-
   Node-Address AVP within the HAR, or else leave this allocation
   responsibility for the Home Agent.

   Upon receipt of the HAR, the Home Agent first processes the Diameter
   message. If the HAR is invalid, a HAA is returned with the Result-
   Code AVP set to DIAMETER_ERROR_BAD_HAR (see section 3.0).  Otherwise,
   the Home Agent processes the MIP-Reg-Request AVP and creates the
   Registration Reply, encapsulating it within the MIP-Reg-Reply AVP.
   If a home address is needed, the Home Agent MUST assign one and
   include the address in both the Registration Reply and within the
   MIP-Mobile-Node-Address AVP. The Diameter response is then forwarded
   to the AAAH.

   Upon receipt of the HAA, the AAAH sets the Command-Code field to AA-
   Mobile-Node-Answer (AMA) and forwards the message to the AAAF.  The
   AAAH includes the MIP-Home-Agent-Address and MIP-Mobile-Node-Address
   AVPs in the AMA message, enabling appropriate firewall controls for
   the penetration of tunneled traffic between the Home Agent and the
   Mobile Node.

   The AAAF is responsible for ensuring that the AMA message is properly
   forwarded to the correct foreign agent.


1.3  Allocation of Home Agent in Foreign Network

   The Diameter Mobile IP extension allows a Home Agent to be allocated
   in a foreign network, as required in [3, 16]. When a foreign agent
   detects that the mobile node has a home agent address equal to
   0.0.0.0 or 255.255.255.255 in the Registration Request message, it
   MUST add a MIP-Feature-Vector AVP with the Home-Agent-Requested flag
   set to one.  If the home agent address is equal to 255.255.255.255,
   then the foreign agent also MUST set the Home-Address-Allocatable-
   Only-in-Home-Domain flag equal to one. If the home agent address is
   set to 0.0.0.0, the foreign agent MUST set the Home-Address-
   Allocatable-Only-in-Home-Domain flag equal to zero.

   When the AAAF receives a AMR message with the Home-Agent-Requested
   flag set to one, and the Home-Address-Allocatable-Only-in-Home-Domain
   flag equal to zero, AAAF MAY set the Foreign-Home-Agent-Available
   flag in the MIP-Feature-Vector AVP to inform the AAAH that it is
   willing and able to assign a Home Agent for the Mobile Node.

   In the event that the mobile node requests a home agent in the



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   foreign network, and the AAAF authorizes its use, the AAAF MUST set
   the Home-Agent-In-Foreign-Network bit in the MIP-Feature-Vector AVP.
   This could happen when the AAA request is sent to "extend" a mobile
   node's current session.

   When the AAAH receives a AMR message, it first checks the
   authentication data supplied by the mobile node, according to the
   MIP-Reg-Request AVP and MIP-MN-AAA-Auth AVP, and determines whether
   to authorize the mobile node.  If the AMR indicates that the AAAF has
   offered to allocate a home agent for the mobile node, then the AAAH
   must decide whether its local policy would allow the user to have a
   Home Agent in the foreign network.  If so, and after checking
   authorization from the data in the AMR message, the AAAH sends the
   HAR message to the AAAF that does not contain the MIP-Home-Agent-
   Address. The AAAF MUST allocate a Home Agent, if one has not already
   been assigned to the Mobile Node, and the AAAF forwards the HAR
   message to the Home Agent.

                           Visited                           Home
                            Domain                          Domain
                          +--------+ ------- AMR -------> +--------+
                          |  AAAF  | <------ HAR -------- |  AAAH  |
                          |        |                      |        |
                     +--->| server | ------- HAA -------> | server |
                     |    +--------+ <------ AMA -------- +--------+
                     |         ^  |
                     |         |  |
             HAR/HAA |     AMR |  | AMA
                     v         |  v
             +---------+       +---------+
             |   Home  |       | Foreign |
             |  Agent  |       |  Agent  |
             +---------+       +---------+
                                       ^
                  +--------+           |
                  | Mobile |<----------+
                  | Node   |  Mobile IP
                  +--------+
             Figure 3: Home Agent allocated in Visited Domain

   Upon receipt of a HAA from the Home Agent in the Visited Domain, with
   the Result-Code AVP indicating success, the AAAF forwards the HAA to
   the AAAH in the home domain. The AMA is then constructed, and issued
   to the AAAF, and finally to the FA. The HAA and AMA MUST include the
   MIP-Home-Agent-Address and the MIP-Mobile-Node-Address AVPs.






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   Mobile Node   Foreign Agent    Home Agent        AAAF         AAAH
   -----------   -------------  -------------   ----------    ----------

      <----Challenge----
    Reg-Req (Response)->
                         ------------AMR------------->
                                                     -----AMR---->
                                                     <----HAR-----
                                      <-----HAR------
                                      ------HAA------>
                                                     -----HAA---->
                                                     <----AMA-----
                       <-------------AMA------------
       <---Reg-Reply----
               Figure 4: Mobile IP/Diameter Message Exchange

   If the Mobile Node moves to another Foreign Network, it MAY either
   request to keep the same Home Agent within the old foreign network,
   or request to get a new one in the new foreign network. If the AAAH
   is willing to provide the requested service, the mobile node will
   have to interact with two AAAFs.

   Figure 5 shows the message flows for a Mobile Node requesting to keep
   the Home Agent assigned in Foreign network 1 when it moves to foreign
   network 2. Upon reception of the AMR in Foreign network 2, the AAAF
   follows the procedures described earlier and forwards AMR to the
   Mobile Node's home network, i.e. its AAAH. If the Mobile Node was
   successfully authenticated the AAAH checks for the MIP-Home-Agent-
   Address and the MIP-Previous-FA-FQDN AVPs. If a AAAH deduces that the
   Mobile Node has moved to a new domain, it must check whether the
   Mobile can still use the previously assigned Home Agent.




















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                   +---------------+ +---------------+ +-------------+
                   |Foreign net 2  | |Foreign net 1  | |Home network |
                   |               | |               | |             |
      Mobile Node  |  FA      AAAF | |  HA     AAAF  | |    AAAH     |
      -----------  | ----     ---- | | ----   ------ | |   ------    |
                   +---------------+ +---------------+ +-------------+

      <----Challenge----
      Reg-Req (Response)->
                       ---AMR--->
                                ----------------AMR--------------->
                                                     <-----HAR-----
                                        <---HAR----
                                        ----HAA--->
                                                     ------HAA---->
                                <---------------AMA----------------
                       <--AMA----
       <----Reg-Reply-----
      Figure 5: Request to access Home Agent from new Foreign Network

   If the Mobile Node is allowed to keep the Home Agent the AAAH then
   sends a HAR, which contains the Mobile IP Registration Request
   message data encapsulated in the MIP-Reg-Request AVP and the MIP-
   Home-Agent-Address AVP with Home Agent address, as well as any
   optional KDC session keys, to the AAAF in foreign network 1.  Upon
   reception the AAAF in foreign network 1 will forward the HAR to the
   Home Agent if its local policy allows such service. If the AAAF does
   not permit such service, it MUST return a
   DIAMETER_ERROR_NO_FOREIGN_HA_SERVICE.

   When the AAAF receives a successful HAA, the AAAF will forward the
   HAA back to the AAAH. The HAA MUST include the MIP-Home-Agent-Address
   and the MIP-Mobile-Node-Address AVPs. The AAAH will then send back an
   AMA to the AAAF in foreign network 2.

   If the old Foreign Network does not permit the use of its Home Agent
   when the Mobile Node moves to a new foreign network, the AAAH or AAAF
   MUST return an AMA with the Result-Code AVP set to
   DIAMETER_ERROR_HA_NOT_AVAILABLE. Upon receipt of this error, the
   Foreign Agent MUST issue a Mobile IP Registration Reply to the Mobile
   Node with an appropriate error. The Mobile Node MAY attempt to
   request that a new Home Agent and Address be allocated. When the AAAH
   transmits such an error, it MUST issue a Diameter Session-
   Termination-Indication message to the AAAF overseeing the Home Agent
   to enable it to release any resources.


1.4  Co-located Mobile Node



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   In the event that a Mobile Node registers with the Home Agent as a
   co-located Mobile Node, there is no Foreign Agent involved.
   Therefore, when the Home Agent receives the Registration Request, an
   AMR message is sent to the local AAAH server, with the Co-Located-
   Mobile-Node bit set in the MIP-Feature-Vector AVP.

                                          Home
                                         Domain
                                       +--------+
                                       |  AAAH  |
                                       |        |
                                       | server |
                                       +--------+
                                         ^  |
                                         |  |
                                     AMR |  | AMA
                                         |  v
             +--------+               +---------+
             | Mobile | Registration  |  Home   |
             | Node   |-------------->|  Agent  |
             +--------+    Request    +---------+
                     Figure 6: Co-located Mobile Node

         If the MN-HA-Key-Requested bit was set in the AMR message from
         the Home Agent, the Home Agent and Mobile Node's session keys
         would be present in the AMA message.


1.5  Diameter Session Termination

   A Foreign and Home Agent following this specification MAY expect
   their respective Diameter servers to maintain session state
   information for each mobile node in their networks. In order for the
   Diameter Server to release any resources allocated to a specific
   mobile node, the mobility agents MUST send a Session-Termination-
   Request (STR) [1] to their respective Diameter servers.

   The Home Diameter server SHOULD only deallocate all resources after
   the STR is received from the Home Agent. This ensures that a Mobile
   Node that moves from one Foreign Agent to another (hand-off) does not
   cause the Home Diameter Server to free all resources for the Mobile
   Node. The Diameter Server is free to initiate the session termination
   at any time by issuing the Session-Termination-Ind (STI) [1].


1.6  Advertising extension support

   Diameter nodes conforming to this specification MAY advertise support



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   by including the value of four (4) in either the Device-Reboot-Ind
   Command's [1] Auth-Extension-Id or Acct-Extension-Id AVPs.


2.0  Command-Code Values

   This section defines Command-Code [1] values that MUST be supported
   by all Diameter implementations conforming to this specification.
   The following Command Codes are defined in this specification:

      Command-Name             Abbreviation    Code       Section
      -----------------------------------------------------------
      AA-Mobile-Node-Answer        AMA         261          2.2
      AA-Mobile-Node-Request       AMR         260          2.1
      Home-Agent-MIP-Answer        HAA         263          2.4
      Home-Agent-MIP-Request       HAR         262          2.3


2.1  AA-Mobile-Node-Request (AMR) Command

   The AA-Mobile-Node-Request (AMR), indicated by the Command-Code field
   set to 260, is sent by an attendant, acting as a Diameter client, to
   a server in order to request the authentication and authorization of
   a Mobile Node. The Foreign Agent (or Home Agent in the case of a co-
   located Mobile Node) uses information found in the Registration
   Request to construct the following AVPs that are to be included as
   part of the AMR:

          home address (MIP-Mobile-Node-Address AVP),
          home agent address (MIP-Home-Agent-Address AVP),
          mobile node NAI (User-Name AVP [1]).
          MN-HA Key Request (MIP-Feature-Vector AVP)
          MN-FA Key Request (MIP-Feature-Vector AVP)

   If the mobile node's home address is zero, the foreign or home agent
   MUST NOT include a MIP-Mobile-Node-Address AVP in the AMR. If the
   home agent address is zero or all ones, the MIP-Home-Agent-Address
   AVP MUST NOT be present in the AMR.

   If a Foreign Agent is used in a visited network, the AAAF MAY set the
   Foreign-Home-Agent-Available flag in the MIP-Feature-Vector AVP in
   the AMR message to indicate that it is willing to assign a Home Agent
   in the visited domain.

   If the MIP-Previous-FA-FQDN AVP is found in the request, the Diameter
   client requests that the server return the registration key that was
   assigned to the previous Foreign Agent for use with the Mobile Node
   and Home Agent. The registration key is identified through the use of



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   the User-Name AVP.

   Message Format

      <AA-Mobile-Node-Request> ::= < Diameter Header: 260 >
                                   < Session-ID >
                                   { Auth-Extension-Id }
                                   { User-Name }
                                   { Destination-Realm }
                                   { Origin-FQDN }
                                   { Origin-Realm }
                                   { MIP-Reg-Request }
                                   { MIP-MN-AAA-Auth }
                                   [ MIP-Mobile-Node-Address ]
                                   [ MIP-Home-Agent-Address ]
                                   [ MIP-Feature-Vector ]
                                   [ Authorization-Lifetime ]
                                   [ MIP-FA-MN-Preferred-SPI ]
                                   [ MIP-FA-HA-Preferred-SPI ]
                                   [ MIP-Previous-FA-FQDN ]
                                   [ MIP-Previous-FA-Addr ]
                                   [ MIP-FA-Challenge ]
                                   [ Destination-FQDN ]
                                 * [ AVP ]
                                 * [ Proxy-Info ]
                                 * [ Route-Record ]


2.2  AA-Mobile-Node-Answer (AMA) Command

   The AA-Mobile-Node-Answer (AMA), indicated by the Command-Code field
   set to 261, is sent by the AAAH in response to the AA-Mobile-Node-
   Request message.  The Result-Code AVP MAY contain one of the values
   defined in section 3.0, in addition to the values defined in [1]. An
   AMA message with the Result-Code AVP indicating success MUST also
   include the MIP-Reg-Reply AVP.

   The MIP-Home-Agent-Address AVP contains the Home Agent assigned to
   the Mobile Node, while the MIP-Mobile-Node-Address AVP contains the
   home address that was assigned. A successful AMA message MUST include
   the MIP-Home-Agent-Address, MIP-Home-Mobile-Node-Address AVP and
   MIP-Reg-Reply AVPs.

   The AMA message MUST contain the MIP-FA-to-HA-Key, MIP-FA-to-MN-Key
   and MIP-Reg-Reply AVPs if they were received by AAAH in the HAA
   message.

   The MIP-MN-to-HA-Key and MIP-HA-to-MN-Key AVPs MUST be present if the



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   session keys were requested in the AMR, and the Co-Located-Mobile-
   Node bit was set in the MIP-Feature-Vector AVP.

   Message Format

      <AA-Mobile-Node-Answer> ::= < Diameter Header: 261 >
                                  < Session-Id >
                                  { Auth-Extension-Id }
                                  { Session-Timeout }
                                  { Authorization-Lifetime }
                                  { Result-Code }
                                  { Origin-FQDN }
                                  { Origin-Realm }
                                  { Destination-FQDN }
                                  [ Error-Reporting-FQDN ]
                                  [ MIP-Reg-Reply ]
                                  [ MIP-MN-to-HA-Key ]
                                  [ MIP-FA-to-MN-Key ]
                                  [ MIP-FA-to-HA-Key ]
                                  [ MIP-MN-to-HA-Key ]
                                  [ MIP-HA-to-MN-Key ]
                                  [ MIP-Home-Agent-Address ]
                                  [ MIP-Mobile-Node-Address ]
                                  [ Original-Session-Id ]
                                  [ Filter-Rule ]
                                * [ AVP ]
                                * [ Proxy-Info ]
                                * [ Route-Record ]


2.3  Home-Agent-MIP-Request (HAR) Command

   The Home-Agent-MIP-Request (HAR), indicated by the Command-Code field
   set to 262, is sent by the AAA to the Home Agent. If the Home Agent
   is to be assigned in a foreign network, the HAR is issued by the AAAH
   and forwarded by the AAAF. If the HAR message does not include a
   MIP-Mobile-Node-Address AVP, and the Registration Request has 0.0.0.0
   for the home address, and the HAR is successfully processed, the Home
   Agent MUST allocate one such address to the mobile node. If the home
   agent's local AAA server allocates the mobile node's home address, it
   MUST include the assigned address in an MIP-Mobile-Node-Address AVP.

   When registration keys are requested for use by the mobile node (see
   section 6.0), the AAAH MUST create them and include them in the HAR
   message.  When a Foreign-Home registration key is requested, it will
   be created and distributed by the AAA server in the same domain as
   the home agent.




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   Message Format

      <Home-Agent-MIP-Request> ::= < Diameter Header: 262 >
                                   < Session-Id >
                                   { Auth-Extension-Id }
                                   { Session-Timeout }
                                   { Authorization-Lifetime }
                                   { MIP-Reg-Request }
                                   { Origin-FQDN }
                                   { Origin-Realm }
                                   { User-Name }
                                   { Destination-Realm }
                                   [ Destination-FQDN ]
                                   [ MIP-MN-to-HA-Key ]
                                   [ MIP-MN-to-FA-Key ]
                                   [ MIP-HA-to-MN-Key ]
                                   [ MIP-HA-to-FA-Key ]
                                   [ MIP-FA-to-MN-Key ]
                                   [ MIP-FA-to-HA-Key ]
                                   [ MIP-Mobile-Node-Address ]
                                   [ MIP-Home-Agent-Address ]
                                   [ Filter-Rule ]
                                 * [ AVP ]
                                 * [ Proxy-Info ]
                                 * [ Route-Record ]


2.4  Home-Agent-MIP-Answer (HAA) Command

   The Home-Agent-MIP-Answer (HAA), indicated by the Command-Code field
   set to 263, is sent by the Home Agent to its local AAA server in
   response to a Home-Agent-MIP-Request. If the home agent allocated a
   home address for the Mobile Node, the address MUST be included in the
   MIP-Mobile-Node-Address AVP. The Result-Code AVP MAY contain one of
   the values defined in section 3.0 instead of the values defined in
   [1].















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   Message Format

      <Home-Agent-MIP-Answer> ::= < Diameter Header: 263 >
                                  < Session-Id >
                                  { Auth-Extension-Id }
                                  { Session-Timeout }
                                  { Authorization-Lifetime }
                                  { Result-Code }
                                  { Origin-FQDN }
                                  { Origin-Realm }
                                  { Destination-FQDN }
                                  [ Error-Reporting-FQDN ]
                                  [ MIP-Reg-Reply ]
                                  [ MIP-Home-Agent-Address ]
                                  [ MIP-Mobile-Node-Address ]
                                  [ MIP-FA-to-MN-Key ]
                                  [ MIP-FA-to-HA-Key ]
                                  [ Filter-Rule ]
                                * [ AVP ]
                                * [ Proxy-Info ]
                                * [ Route-Record ]


3.0  Result-Code AVP Values

   This section defines new Result-Code [1] values that MUST be
   supported by all Diameter implementations that conform to this
   specification.


3.1  Transient Failures

   Errors that fall within the transient failures category are used to
   inform a peer that the request could not be satisfied at the time it
   was received, but MAY be able to satisfy the request in the future.

      DIAMETER_ERROR_AUTH_FAILURE        4004
         This error code is used by AAAH to inform AAAF that the
         authentication data in the MN-AAA authentication extension is
         invalid.

      DIAMETER_ERROR_MIP_REPLY_FAILURE   4005
         This error code is used by the Home Agent when processing of
         the Registration Request has failed.

      DIAMETER_ERROR_HA_NOT_AVAILABLE    4006
         This error code is used to inform the Foreign Agent that the
         requested Home Agent cannot be assigned to the Mobile Node at



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         this time. The Foreign Agent MUST return a Mobile IP
         Registration Reply to the Mobile Node with an appropriate error
         code.


4.0  DSI-Event Values

   This section defines new DSI-Event [1] values that MUST be supported
   by all Diameter implementations that conform to this specification.


4.1  Transient Failure Events

   Errors that fall within the transient failures category are used to
   inform a peer that the request could not be satisfied at the time it
   was received, but MAY be able to satisfy the request if the error is
   corrected.

      DIAMETER_ERROR_BAD_KEY             4002
         This error code is used by the Home Agent to indicate to the
         local Diameter server that the key generated is invalid.

      DIAMETER_ERROR_BAD_HOME_ADDRESS    4003
         This error code is used by the Home Agent to indicate that the
         Home Address chosen by the Mobile Node or assigned by the local
         Diameter server is unavailable.

      DIAMETER_ERROR_BAD_HAR-day         4004
         This error code is used by HA to inform the AAA server that the
         Home-Agent-Request (HAR) message could not be processed
         correctly.


4.2  Permanent Failure Events

   Errors that fall within the permanent failures category are used to
   inform the peer that the request failed, and cannot be satisfied by
   the originator of the Device-Status-Ind. The receiver of a DSI
   message with the DSI-Event set to a value that falls within this
   event class SHOULD forward the message to an alternate peer, if one
   is available.

      DIAMETER_ERROR_NO_FOREIGN_HA_SERVICE 5009
         This error is used by the AAAF to inform the AAAH that
         allocation of a Home Agent in the Foreign Agent is not
         permitted at this time.





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5.0  Mandatory AVPs

   The following table describes the Diameter AVPs defined in the Mobile
   IP extension, their AVP Code values, types, possible flag values and
   whether the AVP MAY be encrypted.

                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|MAY |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
   -----------------------------------------|----+-----+----+-----|----|
   Filter-Rule      400  5.10    OctetString| M  |  P  |    |  V  | Y  |
   MIP-Auth-Input-  338  5.8.2   Unsigned32 | M  |  P  |    |  V  | Y  |
     Data-Length                            |    |     |    |     |    |
   MIP-             339  5.8.3   Unsigned32 | M  |  P  |    |  V  | Y  |
     Authenticator-Length                   |    |     |    |     |    |
   MIP-             340  5.8.4   Unsigned32 | M  |  P  |    |  V  | Y  |
     Authenticator-Offset                   |    |     |    |     |    |
   MIP-FA-Challenge 344  5.9     OctetString| M  |  P  |    |  V  | Y  |
   MIP-Feature-     337  5.7     Unsigned32 | M  |  P  |    |  V  | Y  |
     Vector                                 |    |     |    |     |    |
   MIP-Home-Agent-  334  5.4     Address    | M  |  P  |    |  V  | Y  |
     Address                                |    |     |    |     |    |
   MIP-MN-AAA-Auth  322  5.8     Grouped    | M  |  P  |    |  V  | Y  |
   MIP-MN-AAA-SPI   341  5.8.1   Unsigned32 | M  |  P  |    |  V  | Y  |
   MIP-Mobile-Node- 333  5.3     Address    | M  |  P  |    |  V  | Y  |
     Address                                |    |     |    |     |    |
   MIP-Previous-FA- 336  5.6     Address    | M  |  P  |    |  V  | Y  |
     Addr                                   |    |     |    |     |    |
   MIP-Previous-FA- 335  5.5     OctetString| M  |  P  |    |  V  | Y  |
     FQDN                                   |    |     |    |     |    |
   MIP-Reg-Request  320  5.1     OctetString| M  |  P  |    |  V  | Y  |
   MIP-Reg-Reply    321  5.2     OctetString| M  |  P  |    |  V  | Y  |


5.1  MIP-Reg-Request AVP

   The MIP-Reg-Request AVP (AVP Code 320) is of type OctetString and
   contains the Mobile IP Registration Request [4] sent by the Mobile
   Node to the Foreign Agent.


5.2  MIP-Reg-Reply AVP

   The MIP-Reg-Reply AVP (AVP Code 321) is of type OctetString and
   contains the Mobile IP Registration Reply [4] sent by the Home Agent
   to the Foreign Agent.



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5.3  MIP-Mobile-Node-Address AVP

   The Mobile-Node-Address AVP (AVP Code 333) is of type Address and
   contains the Mobile Node's Home Address.


5.4  MIP-Home-Agent-Address AVP

   The Home-Agent-Addess AVP (AVP Code 334) is of type Address and
   contains the Mobile Node's Home Agent Address.


5.5  MIP-Previous-FA-FQDN AVP

   The MIP-Previous-FA-FQDN AVP (AVP Code 335) is of type OctetString
   and contains the Fully Qualified Domain Name of the Mobile Node's old
   Foreign Agent, encoded in the UTF-8 [12] format. The Mobile Node MAY
   include this information in the Registration Request when it moves
   its point of attachment to a new foreign agent under the same
   administrative domain as the old FA.

   When this AVP is present in the AA-Mobile-Node-Request, it indicates
   that the local Diameter server overseeing the Foreign Agent should
   attempt to return the registration key that was previously allocated
   to the old Foreign Agent for the Mobile Node. The registration key is
   identified through the use of the User-Name AVP, which MUST be
   present if this extension is present.

   In many circumstances, this allows the Mobile Node to move from one
   Foreign Agent to another within the same administrative domain
   without having to send the request back to the Mobile Node's Home
   Diameter Server (AAAH).


5.6  MIP-Previous-FA-Addr AVP

   The MIP-Previous-FA-Addr AVP (AVP Code 336) is of type Address and
   contains the IP Address of the Mobile Node's old Foreign Agent.  The
   Mobile Node MAY include this information in the Previous Foreign
   Agent Notification Extension to the Mobile IP Registration Request
   when it moves its point of attachment to a new foreign agent.

   When this AVP is present in the AA-Mobile-Node-Request, it indicates
   that the local Diameter server overseeing the Foreign Agent should
   attempt to return the registration key that was previously allocated
   to the old Foreign Agent for the Mobile Node. The registration key is
   identified through the use of the User-Name AVP, which MUST be
   present if this extension is present.



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   In many circumstances, this allows the Mobile Node to move from one
   Foreign Agent to another within the same administrative domain
   without having to send the request back to the Mobile Node's Home
   Diameter Server (AAAH).


5.7  MIP-Feature-Vector AVP

   The MIP-Feature-Vector AVP (AVP Code 337) is of type Unsigned32 and
   is added with flag values set by the Foreign Agent or by the AAAF
   owned by the same administrative domain as the Foreign Agent.  The
   Foreign Agent SHOULD include MIP-Feature-Vector AVP within the AMR
   message it sends to the AAAF.

   Flag values currently defined include:
         1       Mobile-Node-Home-Address-Requested
         2       Home-Address-Allocatable-Only-in-Home-Domain
         4       Home-Agent-Requested
         8       Foreign-Home-Agent-Available
         16      MN-HA-Key-Request
         32      MN-FA-Key-Request
         64      FA-HA-Key-Request
         128     Home-Agent-In-Foreign-Network
         256     Co-Located-Mobile-Node

   The flags are set according to the following rules.

   If the mobile node includes a valid home address (i.e., not equal to
   0.0.0.0 or 255.255.255.255) in its Registration Request, the Foreign
   Agent zeroes the Mobile-Node-Home-Address-Requested flag in the MIP-
   Feature-Vector AVP.

   If the mobile node sets the home address field equal to 0.0.0.0 in
   its Registration Request, the Foreign Agent sets the Mobile-Node-
   Home-Address-Requested flag to one.

   If the mobile node sets the home agent field equal to 255.255.255.255
   in its Registration Request, the Foreign Agent sets both the Home-
   Agent-Requested flag and the Home-Address-Allocatable-Only-in-Home-
   Domain flag to one in the MIP-Feature-Vector AVP.

   If the mobile node sets the home agent field equal to 0.0.0.0 in its
   Registration Request, the Foreign Agent sets the Home-Agent-Requested
   flag to one, and zeroes the Home-Address-Allocatable-Only-in-Home-
   Domain flag in the MIP-Feature-Vector AVP.

   Whenever the Foreign Agent sets either the Mobile-Node-Home-Address-
   Requested flag or the Home-Agent-Request flag to one, it MUST set the



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   MN-HA-Key-Request flag to one. The MN-HA-Key-Request flag is also set
   to one if the mobile node includes a Generalized MN-HA Key Request
   [15] extension, with the subtype set to AAA.

   If the mobile node includes a Generalized MN-FA Key Request [15]
   extension with the AAA subtype in its Registration Request, the
   Foreign Agent sets the MN-FA-Key-Request flag to one in the MIP-
   Feature-Vector AVP.

   If the mobile node requests a home agent in the foreign network by
   setting the home address field to all ones, and the AAAF authorizes
   the request, the AAAF MUST set the Home-Agent-In-Foreign-Network bit
   to one.

   If the Home Agent receives a Registration Request from the Mobile
   Node indicating that the MN is acting as a Co-Located Mobile Node,
   the Home Agent sets the Co-Located-Mobile-Node bit to one.

   If the Foreign Agent's local policy allows it to receive AAA Session
   Keys, and it does not have any existing keys with the Home Agent, it
   MAY set the FA-HA-Key-Request flag.

   The Foreign Agent MUST NOT set the Foreign-Home-Agent-Available, and
   Home-Agent-In-Foreign-Network flag to one.

   When the AAAF receives the AMR message, it MUST first verify that the
   sender was an authorized Foreign Agent.  The AAAF then takes any
   actions indicated by the settings of the MIP-Feature-Vector AVP
   flags.  The AAAF then MAY set additional flags.  Only the AAAF may
   set the Foreign-Home-Agent-Available flag to one.  This is done
   according to local administrative policy.  When the AAAF has finished
   setting additional flags according to its local policy, then the AAAF
   transmits the AMR with the possibly modified MIP-Feature-Vector AVP
   to the AAAH.


5.8  MIP-MN-AAA-Auth AVP

   The MN-AAA-Auth AVP (AVP Code 322) is of type Grouped and contains
   some ancillary data to simplify processing of the authentication data
   in the Mobile IP Registration Request [4] by the target AAA server.
   Its value has the following ABNF grammar:

      MIP-MN-AAA-Auth   = ma-spi authinlen authlen authoffset
         ma-spi          = ; MIP-MN-AAA-SPI, See Section 5.8.1
         authinlen       = ; MIP-Auth-Input-Data-Length, /
                           ; See Section 5.8.2
         authlen         = ; MIP-Authenticator-Length, /



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                           ; See Section 5.8.3
         authoffset      = ; MIP-Authenticator-Offset, /
                           ; See Section 5.8.4

      +---------------------------------------------------------------+
      |                 AVP Header (AVP Code = 322)                   |
      +---------------------------------------------------------------+
      |                     MIP-MN-AAA-SPI AVP                        |
      +---------------------------------------------------------------+
      |                MIP-Auth-Input-Data-Length AVP                 |
      +---------------------------------------------------------------+
      |                 MIP-Authenticator-Length AVP                  |
      +---------------------------------------------------------------+
      |                 MIP-Authenticator-Offset AVP                  |
      +---------------------------------------------------------------+


5.8.1  MIP-MN-AAA-SPI AVP

   The MIP-MN-AAA-SPI AVP (AVP Code 341) is of type Unsigned32 and
   indicates the algorithm by which the targeted AAA server (AAAH)
   should attempt to validate the Authenticator computed by the mobile
   node over the Registration Request data.


5.8.2  MIP-Auth-Input-Data-Length AVP

   The MIP-Auth-Input-Data-Length AVP (AVP Code 338) is of type
   Unsigned32 and contains the length, in bytes, of the Registration
   Request data (data portion of MIP-Reg-Request AVP) that should be
   used as input to the algorithm (indicated by the MN-AAA-SPI AVP) used
   to determine whether the Authenticator Data supplied by the Mobile
   Node is valid.


5.8.3  MIP-Authenticator-Length AVP

   The MIP-Authenticator-Length AVP (AVP Code 339) is of type Unsigned32
   and contains the length of the authenticator to be validated by the
   targeted AAA server (i.e., AAAH).


5.8.4  MIP-Authenticator-Offset AVP

   The MIP-Authenticator-Offset AVP (AVP Code 340) is of type Unsigned32
   and contains the offset into the Registration Request Data, of the
   authenticator to be validated by the targeted AAA server (i.e.,
   AAAH).



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5.9   MIP-FA-Challenge

   The MIP-FA-Challenge AVP (AVP Code 344) is of type OctetString and
   contains the challenge advertised by the Foreign Agent to the Mobile
   Node. This AVP MUST be present in the AMR if the Mobile Node used the
   RADIUS-style MN-AAA computation algorithm.


5.10  Filter-Rule AVP

   The Filter-Rule AVP (AVP Code 400) is of type OctetString, encoded in
   the UTF-8 [29] format, and provides filter rules that need to be
   configured on the Foreign or Home Agent for the user. One or more
   such AVPs MAY be present in an authorization response.

   Each packet can be filtered based on the following information that
   is associated with it:

      Direction                          (in or out)
      Source and destination IP address  (possibly masked)
      Protocol
      Source and destination port        (lists or ranges)
      TCP flags
      IP fragment flag
      IP options
      ICMP types

   Rules for the appropriate direction are evaluated in order, with the
   first matched rule terminating the evaluation.  Each packet is
   evaluated once. If no rule matches, the packet is dropped if the last
   rule evaluated was a permit, and passed if the last rule was a deny.

   The filters in the Filter-Rule AVP MUST follow the format:

      action dir proto from src to dst [options]

      action       permit - Allow packets that match the rule.
                   deny - Drop packets that match the rule.

      dir          "in" is from the terminal, "out" is to the terminal.

      proto        An IP protocol specified by number.  The "ip" keyword
                   means any protocol will match.

      src and dst  <address/mask> [ports]

                   The <address/mask> may be specified as:
                   ipno       An IPv4 or IPv6 number in dotted-quad or



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                              canonical IPv6 form. Only this exact IP
                              number will match the rule.
                   ipno/bits  An IP number as above with a mask width of
                              the form 1.2.3.4/24.  In this case all IP
                              numbers from 1.2.3.0 to 1.2.3.255 will
                              match.  The bit width MUST be valid for
                              the IP version and the IP number MUST NOT
                              have bits set beyond the mask.

                   The sense of the match can be inverted by preceding
                   an address with the not modifier, causing all other
                   addresses to be matched instead.  This does not
                   affect the selection of port numbers.

                      The keyword "any" is 0.0.0.0/0 or the IPv6
                      equivalent.  The keyword "assigned" is the address
                      or set of addresses assigned to the terminal.  The
                      first rule SHOULD be "deny in ip !assigned".

                   With the TCP and UDP protocols, optional ports may be
                   specified as:

                      {port|port-port}[,port[,...]]

                   The `-' notation specifies a range of ports
                   (including boundaries).

                   Fragmented packets which have a non-zero offset (i.e.
                   not the first fragment) will never match a rule which
                   has one or more port specifications.  See the frag
                   option for details on matching fragmented packets.

      options:
         frag    Match if the packet is a fragment and this is not the
                 first fragment of the datagram.  frag may not be used
                 in conjunction with either tcpflags or TCP/UDP port
                 specifications.

         ipoptions spec
                 Match if the IP header contains the comma separated
                 list of options specified in spec. The supported IP
                 options are:

                 ssrr (strict source route), lsrr (loose source route),
                 rr (record packet route) and ts (timestamp). The
                 absence of a particular option may be denoted with a
                 `!'.




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         tcpoptions spec
                 Match if the TCP header contains the comma separated
                 list of options specified in spec. The supported TCP
                 options are:

                 mss (maximum segment size), window (tcp window
                 advertisement), sack (selective ack), ts (rfc1323
                 timestamp) and cc (rfc1644 t/tcp connection count).
                 The absence of a particular option may be denoted with
                 a `!'.

         established
                 TCP packets only. Match packets that have the RST or
                 ACK bits set.

         setup   TCP packets only. Match packets that have the SYN bit
                 set but no ACK bit.

         tcpflags spec
                 TCP packets only. Match if the TCP header contains the
                 comma separated list of flags specified in spec. The
                 supported TCP flags are:

                 fin, syn, rst, psh, ack and urg. The absence of a
                 particular flag may be denoted with a `!'. A rule which
                 contains a tcpflags specification can never match a
                 fragmented packet which has a non-zero offset.  See the
                 frag option for details on matching fragmented packets.

         icmptypes types
                 ICMP packets only.  Match if the ICMP type is in the
                 list types. The list may be specified as any
                 combination of ranges or individual types separated by
                 commas.  The supported ICMP types are:

                 echo reply (0), destination unreachable (3), source
                 quench (4), redirect (5), echo request (8), router
                 advertisement (9), router solicitation (10), time-to-
                 live exceeded (11), IP header bad (12), timestamp
                 request (13), timestamp reply (14), information request
                 (15), information reply (16), address mask request (17)
                 and address mask reply (18).

   There is one kind of packet that the FA MUST always discard, that is
   an IP fragment with a fragment offset of one.  This is a valid
   packet, but it only has one use, to try to circumvent firewalls.

      An FA that is unable to interpret or apply a deny rule MUST



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      terminate the session.  An FA that is unable to interpret or apply
      a permit rule MAY apply a more restrictive rule.  An FA MAY apply
      deny rules of its own before the supplied rules, for example to
      protect the FA owner's infrastructure.

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


6.0  Key Distribution Center

   The mobile node and mobility agents use registration keys to compute
   authentication extensions applied to registration messages, as
   defined in [4]: Mobile-Foreign, Foreign-Home and Mobile-Home.  If
   registration keys are requested the AAA server(s) MUST create them
   after the Mobile Node is successfully authenticated and authorized.

   The keys destined for each mobility entity are encrypted either using
   the secret shared with the entity [1], or via its public key [9], as
   indicated by the relevant security association.  If the AAAH does not
   communicate directly with the Foreign Agent, those keys are encrypted
   using the security association shared with the AAAF.  The
   Authorization-Lifetime AVP contains the number of seconds before
   registration keys destined for the Home Agent and/or Foreign Agent
   expire.  A value of zero indicates infinity (no timeout).

   AAA support for key distribution departs slightly from the existing
   SPI usage, as described in [4].  The SPI values are used as key
   identifiers, meaning that each registration key has its own SPI
   value; nodes that share a key also share an SPI.  If no preferred SPI
   value is indicated, the AAA server MAY generate SPI values for the
   Mobility Agents as opposed to the receiver choosing its own SPI
   value. For example, suppose a Mobile Node and a Foreign Agent share a
   key that was generated by AAAH with a corresponding SPI value of
   37,496. All Mobile-Foreign Authentication extensions will be computed
   by either entity (in this example) using the shared key and MUST
   include the SPI value of 37,496.

   Once the registration keys have been distributed, subsequent Mobile
   IP registrations need not invoke the AAA infrastructure until the
   keys expire.  These registrations MUST include the Mobile-Home
   authentication extension.  In addition, subsequent registrations MUST
   also include Mobile-Foreign authentication extension if the Mobile-
   Foreign key was generated and distributed by AAA; similarly for
   subsequent use of the Foreign-Home authentication extensions.

   Each registration key that is generated by AAA will generally be
   distributed to two parties; for instance, a Mobile-Foreign key goes



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   to both a mobile node and a foreign agent.  The methods by which the
   key is encoded will depend upon the security associations available
   to the AAA server and each recipient of the key.  These methods will
   often be different for the two recipients, so that the registration
   key under consideration has to be encoded twice.

   See sections 7.1 and 7.2 for details about the format of the AVPs
   used to distribute the registration keys.


6.1  Distributing the Mobile-Home Registration Key

   If the mobile node does not have a Mobile-Home registration key, then
   the AAAH is likely to be the only entity trusted that is available to
   the mobile node.  Thus, the AAAH has to generate the Mobile-Home
   registration key, and encode it for eventual consumption by the
   mobile node and home agent.

   If the home agent is in the home domain, then AAAH can directly
   encode the Mobile-Home registration key into a MIP-HA-to-MN-Key AVP
   and include that AVP in the HAR message for delivery to the home
   agent.

   If, on the other hand, the home agent is to be allocated in the
   visited domain, the AAAH does not transmit the HAR to the home agent,
   but instead transmits the HAR to the AAAF. When the AAAF receives the
   HAR, it first allocates a home agent, and then issues the HAR for
   that home agent.

   The AAAH also has to arrange for the key to be delivered to the
   mobile node.  Unfortunately, the AAA server only knows about Diameter
   messages and AVPs, and the mobile node only knows about Mobile IP
   messages and extensions[4].  For this purpose, AAAH encodes the
   Mobile-Home registration key into a MIP-MN-to-HA-Key AVP, using its
   security association with the mobile node, which is added to the HAR
   message, and delivered either to a local home agent, or to the AAAF
   in the case where the home agent is in the visited network. The AAAH
   has to rely on the home agent (that also understands Diameter) to
   transfer the key into a Mobile IP Generalized MN-HA Key Reply
   extension in the Registration Reply message. The home agent can
   format the Reply message and extensions correctly for eventual
   delivery to the mobile node. The resulting Registration Reply is
   added to the MIP-Reg-Reply AVP and added to the AMA.

   After the HAA message is parsed by the AAAH, and transformed into an
   AMA, the AMA message containing the MIP-Reg-Reply AVP will eventually
   be received by the attendant (i.e., the foreign agent). The foreign
   agent can then use that AVP to recreate a Registration Reply message,



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   containing the Generalized MN-HA Key Reply extension, for delivery to
   the mobile node.

   In summary, the AAAH generates the Mobile-Home registration key and
   encodes it into a MIP-HA-to-MN-Key AVP and a MIP-MN-to-HA-Key AVP.
   These AVPs are delivered to a home agent by including them in a HAR
   message sent from either AAAH or AAAF. The home agent decodes the key
   for its own use.  The home agent also copies the encoded registration
   key from the MIP-MN-to-HA-Key AVP into a Generalized MN-HA Key Reply
   extension appended to the Mobile IP Registration Reply message. This
   Registration Reply message MUST also include the Mobile-Home
   authentication extension, created using the newly allocated Mobile-
   Home registration key. The home agent then encodes the Registration
   Reply message and extensions into a MIP-Reg-Reply AVP included as
   part of the HAA message to be sent back to the AAA server.


6.2  Distributing the Mobile-Foreign Registration Key

   The Mobile-Foreign registration key is also generated by AAAH (upon
   request), so that it can be encoded into a MIP-MN-to-FA-Key AVP,
   which is added to the HAR, and copied by the home agent into a
   Generalized MN-FA Key Reply Extension [15] to the Mobile IP
   Registration Reply message. Most of the considerations for
   distributing the Mobile-Foreign registration key are similar to the
   distribution of the Mobile-Home Registration Key.

   If the MIP-FA-to-MN-Key AVP is present in the HAR, the home agent
   MUST ensure that the same AVP is present in the AHA. The AAAH MUST
   ensure that this AVP is present in the AMA, which is sent to the
   foreign agent.


6.3  Distributing the Foreign-Home Registration Key

   If the home agent is in the home domain, then AAAH has to generate
   the Foreign-Home registration key.  Otherwise, it is generated by
   AAAF.

   In either case, the AAA server encodes the registration key into a
   MIP-HA-to-FA-Key AVP and includes that AVP as part of the HAR message
   sent to the home agent, and waits for the HAA message to be returned.

   If the MIP-FA-to-HA-Key AVP was present in the HAR, the same AVP MUST
   be present in the corresponding HAA, which is eventually transformed
   by the AAAH into an AMA message that is transmitted back to the
   foreign agent.




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   Upon receipt of the AMA, the foreign agent recovers the Foreign-Home
   registration key, and uses this key to create a Foreign-Home
   authentication extension to the Registration Reply message.


6.4  Key Distribution Example

   Figure 7 provides an example of subsequent Mobile IP message
   exchange, assuming that AAAH distributed registration keys for all
   three MN-FA, FA-HA and HA-MN authentication extensions.

   Mobile Node                Foreign Agent                 Home Agent
   -----------                -------------                 ----------

   Reg-Req(MN-HA-Auth, MN-FA-Auth)-------->

                              Reg-Req(MN-HA-Auth, FA-HA-Auth)-------->

                              <--------Reg-Rep(MN-HA-Auth, FA-HA-Auth)

   <--------Reg-Rep(MN-HA-Auth, MN-FA-Auth)

                   Figure 7: Mobile IP Message Exchange


7.0  Key Distribution Center (KDC) AVPs

   The Mobile-IP protocol defines a set of security associations shared
   between the Mobile Node, Foreign Agent and Home Agents. These three
   security associations (Mobile-Home, Mobile-Foreign, and Foreign-
   Home), can be dynamically created by the AAAH. This requires that the
   AAAH create Mobile-IP Registration Keys, and that these keys be
   distributed to the three mobile entities, via the Diameter Protocol.
   AAA servers supporting the Diameter Mobile IP Extension MUST
   implement the KDC AVPs defined in this document. In other words, AAA
   servers MUST be able to create three registration keys: the Mobile-
   Home, Mobile-Foreign, and Foreign-Home keys.

   Each of these keys is encrypted two different ways, as needed for
   each key recipient.  The mobile node and home agent registration keys
   are sent to the Home Agent, while the foreign agent's keys are sent
   to the foreign agent via the AAAF.  This leads to six different AVPs,
   since there are three keys, and each one has to be able to be
   encrypted in two different ways.

   The names of the KDC AVPs indicate the two entities sharing the
   security association defined by the encrypted key material; the
   intended receiver of the AVP is the first named entity.  So, for



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   instance, the MIP-MN-to-HA-Key AVP contains the Mobile-Home key
   encrypted in a way that allows it to be recovered by the mobile node.

   If strong authentication and confidentiality of the registration keys
   is required, it is recommended that the strong security extension [9]
   be used.

   The following table describes the Diameter AVPs defined in the Mobile
   IP extension, their AVP Code values, types, possible flag values and
   whether the AVP MAY be encrypted.

                                             +---------------------+
                                             |    AVP Flag rules   |
                                             |----+-----+----+-----|----+
                    AVP  Section             |    |     |SHLD| MUST|MAY |
    Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
    -----------------------------------------|----+-----+----+-----|----|
    MIP-FA-to-MN-Key 326  7.2.1   Grouped    | M  |  P  |    |  V  | Y  |
    MIP-FA-to-HA-Key 328  7.2.2   Grouped    | M  |  P  |    |  V  | Y  |
    MIP-HA-to-FA-Key 329  7.2.3   Grouped    | M  |  P  |    |  V  | Y  |
    MIP-HA-to-MN-Key 332  7.2.4   Grouped    | M  |  P  |    |  V  | Y  |
    MIP-MN-to-FA-Key 325  7.1.1   OctetString| M  |  P  |    |  V  | Y  |
    MIP-MN-to-HA-Key 331  7.1.2   OctetString| M  |  P  |    |  V  | Y  |
    MIP-Peer-SPI     342  7.2.5   Unsigned32 | M  |  P  |    |  V  | Y  |
    MIP-FA-MN-       324  7.3     Unsigned32 | M  |  P  |    |  V  | Y  |
      Preferred-SPI                          |    |     |    |     |    |
    MIP-FA-HA-       327  7.4     Unsigned32 | M  |  P  |    |  V  | Y  |
      Preferred-SPI                          |    |     |    |     |    |
    MIP-Session-Key  343  7.2.6   OctetString| M  |  P  |    |  V  | Y  |
    MIP-Algorithm-   345  7.2.7   Unsigned32 | M  |  P  |    |  V  | Y  |
      Type                                   |    |     |    |     |    |
    MIP-Replay-Mode  346  7.2.8   Unsigned32 | M  |  P  |    |  V  | Y  |


7.1  Mobile Node Registration Keys

   When the AAAH acts as a Key Distribution Center, and it is determined
   that keying material is to be created for Mobile Nodes, the AAAH
   creates the keys and encodes them in the MIP-MN-to-FA-Key and MIP-
   MN-to-HA-Key AVPs as opaque data. The actual format of the AVP value
   is described in [15], and would contains the data immediately
   following the Mobile IP extension header.

   The Mobile IP key described in [15] refers to the AAA SPI, which MUST
   be set to the value the AAAH shares with the Mobile Node. The Key
   Lifetime field is set to the same value as the one found in the
   Authorization-Lifetime AVP.




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7.1.1  MIP-MN-to-FA-Key AVP

   The MIP-MN-to-FA-Key AVP (AVP Code 325) is of type OctetString, and
   contains the Keying material described in the "Unsolicited MN-FA Key
   from AAA Subtype" in [15]. The FA SPI field of the data structure in
   [15] MUST be set to the same value as the MIP-Peer-SPI AVP within the
   FA-to-MN-Key AVP.


7.1.2  MIP-MN-to-HA-Key AVP

   The MIP-MN-to-HA-Key AVP (AVP Code 331) is of type OctetString, and
   contains the Keying material described in the "Unsolicited MN-HA Key
   from AAA Subtype" in [15]. The HA SPI field of the data structure in
   [15] MUST be set to the same value as the MIP-Peer-SPI AVP within the
   HA-to-MN-Key AVP.


7.2  Mobility Agent Session Keys

   The Mobility Agent session keys are the keys created by a Diameter
   server, which it distributes to Foreign and Home Agents, acting as
   Diameter clients.  The lifetime of the generated keys MUST be the
   same as the value of the Authorization-Lifetime AVP. These session
   keys, described below, are of type Grouped, and therefore their value
   have the following ABNF format:

      Mobility Agent Session Key AVP   = Peer-SPI Algorithm-Type /
          Replay-Mode Session-Key
         Peer-SPI        = ; MIP-Peer-SPI, See Section 7.2.5
         Algorithm-Type  = ; MIP-Algorithm-Type, See Section 7.2.7
         Replay-Mode     = ; MIP-Replay-Mode, See Section 7.2.8
         Session-Key     = ; MIP-Session-Key, See Section 7.2.6

   The MIP-Peer-SPI AVP contains the Security Parameter Index, which the
   Mobility Agent MUST use to refer to the Key contained in the MIP-
   Session-Key AVP.

      +---------------------------------------------------------------+
      |                AVP Header (AVP Code = see below)              |
      +---------------------------------------------------------------+
      |                        MIP-Peer-SPI AVP                       |
      +---------------------------------------------------------------+
      |                       MIP-Session-Key AVP                     |
      +---------------------------------------------------------------+


7.2.1  MIP-FA-to-MN-Key AVP



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   The MIP-FA-to-MN-Key AVP (AVP Code 326) is of type Grouped, and
   contains the Foreign Agent's session key, which it shares with the
   Mobile Node. Its format is described in Section 6.2.


7.2.2  MIP-FA-to-HA-Key AVP

   The MIP-FA-to-HA-Key AVP (AVP Code 328) is of type Grouped, and
   contains the Foreign Agent's session key, which it shares with the
   Home Agent. Its format is described in Section 6.2.


7.2.3  MIP-HA-to-FA-Key AVP

   The MIP-HA-to-FA-Key AVP (AVP Code 329) is of type Grouped, and
   contains the Home Agent's session key, which it shares with the
   Foreign Agent. Its format is described in Section 7.2.


7.2.4  MIP-HA-to-MN-Key AVP

   The MIP-HA-to-MN-Key AVP (AVP Code 332) is of type Grouped, and
   contains the Home Agent's session key, which it shares with the
   Mobile Node. Its format is described in Section 7.2.


7.2.5  MIP-Peer-SPI AVP

   The MIP-Peer-SPI AVP (AVP Code 342) is of type Unsigned32, and
   contains the Security Parameter Index to use to reference the key in
   the associated MIP-Session-Key AVP.


7.2.6  MIP-Session-Key AVP

   The MIP-Session-Key AVP (AVP Code 343) is of type OctetString and
   contains the Session Key to be used between two Mobile IP entities.


7.2.7  MIP-Algorithm-Type AVP

   The MIP-Algorithm-Type AVP (AVP Code 345) is of type Unsigned32, and
   contains the Algorithm identifier used to generate the associated
   Mobile IP authentication extension. The following values are
   currently defined:

      0       Prefix+Suffix MD5
      1       HMAC-MD5



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7.2.8  MIP-Replay-Mode AVP

   The MIP-Replay-Mode AVP (AVP Code 346) is of type Unsigned32 and
   contains the replay mode the Home Agent should use when
   authenticating the Mobile Node. Although present in the Grouped AVPs
   sent to the Foreign Agent, this field is ignored.

   The following values are supported (see [4] for more information):

      0       None
      1       Timestamps
      2       Nonces


7.3  MIP-FA-MN-Preferred-SPI AVP

   The MIP-FA-MN-Preferred-SPI AVP (AVP Code 324) is of type Unsigned32
   and is sent in the AA-Mobile-Node-Request by the Foreign Agent. The
   AVP contains the SPI that the Foreign Agent would prefer to have
   assigned by the AAAH in the MIP-FA-to-MN-Key AVP.


7.4  MIP-FA-HA-Preferred-SPI AVP

   The MIP-FA-HA-Preferred-SPI AVP (AVP Code 327) is of type Unsigned32
   and is sent in the AA-Mobile-Node-Request by the Foreign Agent. The
   AVP contains the SPI that the Foreign Agent would prefer to have
   assigned by the AAAH in the MIP-FA-to-HA-Key AVP.


8.0  Accounting AVPs

   This section will define the Accounting AVPs that are specific to
   Mobile IP, and MUST be included in all Accounting-Request messages.
   These AVPs MAY be present in the corresponding Accounting-Answer
   messages as well.


8.1  Accounting-Input-Octets AVP

   The Accounting-Input-Octets AVP (AVP Code 42) is of type Unsigned64,
   and contains the number of octets in IP packets received by the user.


8.2  Accounting-Output-Octets AVP

   The Accounting-Output-Octets AVP (AVP Code 43) is of type Unsigned64,
   and contains the number of octets in IP packets sent to the user.



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8.3  Accounting-Session-Time AVP

   The Accounting-Session-Time AVP (AVP Code 46) is of type Unsigned32,
   and indicates the length of the current session in seconds.


8.4  Accounting-Input-Packets AVP

   The Accounting-Input-Packets (AVP Code 47) is of type Unsigned64, and
   contains the number of IP packets received by the user.


8.5  Accounting-Output-Packets AVP

   The Accounting-Output-Packets (AVP Code 48) is of type Unsigned64,
   and contains the number of IP packets sent to the user.


9.0  Interactions with Resource Management

   The Resource Management extension [2] provides the ability for a
   Diameter node to query a peer for session state information. The
   document states that service-specific extensions are responsible for
   specifying what AVPs are to be present in the Resource-Token [2] AVP.

   In addition to the AVPs listed in [2], the Resource-Token AVP MUST
   include the MIP-Mobile-Node-Address and the MIP-Home-Agent-Address
   AVPs.


10.0  AVP Occurrence Tables

   The following tables presents the AVPs defined in this document, and
   specifies in which Diameter messages they MAY, or MAY NOT be present.
   Note that AVPs that can only be present within a Grouped AVP are not
   represented in this table.

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







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10.1  Mobile IP Command AVP Table

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


                                 +-----------------------+
                                 |      Command-Code     |
                                 |-----+-----+-----+-----+
   Attribute Name                | AMR | AMA | HAR | HAA |
   ------------------------------|-----+-----+-----+-----+
   Authorization-Lifetime        | 1   | 1   | 1   | 1   |
   Destination-FQDN              | 0+  | 1   | 0+  | 1   |
   Destination-Realm             | 1   | 0   | 1   | 0   |
   Error-Reporting-FQDN          | 0   | 0+  | 0   | 0+  |
   Auth-Extension-Id             | 1   | 1   | 1   | 1   |
   Filter-Rule                   | 0   | 0+  | 0+  | 0   |
   MIP-FA-to-HA-Key              | 0   | 0-1 | 0-1 | 0-1 |
   MIP-FA-to-MN-Key              | 0   | 0-1 | 0-1 | 0-1 |
   MIP-Feature-Vector            | 0-1 | 0   | 0   | 0   |
   MIP-FA-HA-Preferred-SPI       | 0-1 | 0   | 0   | 0   |
   MIP-FA-MN-Preferred-SPI       | 0-1 | 0   | 0   | 0   |
   MIP-HA-to-FA-Key              | 0   | 0   | 0-1 | 0   |
   MIP-HA-to-MN-Key              | 0   | 0   | 0-1 | 0   |
   MIP-Home-Agent-Address        | 0-1 | 0-1 | 0   | 0-1 |
   MIP-MN-AAA-Auth               | 1   | 0   | 0   | 0   |
   MIP-MN-to-FA-Key              | 0   | 0   | 0-1 | 0   |
   MIP-MN-to-HA-Key              | 0   | 0-1 | 0-1 | 0   |
   MIP-Mobile-Node-Address       | 0-1 | 0-1 | 0-1 | 0-1 |
   MIP-Previous-FA-Address       | 0-1 | 0   | 0   | 0   |
   MIP-Previous-FA-FQDN          | 0-1 | 0   | 0   | 0   |
   MIP-Reg-Reply                 | 0   | 0-1 | 0   | 0-1 |
   MIP-Reg-Request               | 1   | 0   | 1   | 0   |
   Origin-FQDN                   | 1   | 1   | 1   | 1   |
   Origin-Realm                  | 1   | 1   | 1   | 1   |
   Proxy-Info                    | 0+  | 0+  | 0+  | 0+  |
   Result-Code                   | 0   | 1   | 0   | 1   |
   Route-Record                  | 0+  | 0+  | 0+  | 0+  |
   Session-Id                    | 1   | 1   | 1   | 1   |
   Session-Timeout               | 0   | 1   | 1   | 1   |
   User-Name                     | 1   | 0   | 1   | 0   |
   ------------------------------|-----+-----+-----+-----|


10.2  Accounting AVP Table

   The table in this section is used to represent which AVPs defined in
   this document are to be present in the Accounting messages, defined



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   in [1].

                                 +-----------------------+
                                 |      Command-Code     |
                                 |-----+-----+-----+-----+
   Attribute Name                | ACR | ACA | API | ASI |
   ------------------------------|-----+-----+-----+-----+
   Accounting-Input-Octets       | 1   | 1   | 0   | 0   |
   Accounting-Input-Packets      | 1   | 1   | 0   | 0   |
   Accounting-Output-Octets      | 1   | 1   | 0   | 0   |
   Accounting-Output-Packets     | 1   | 1   | 0   | 0   |
   Accounting-Session-Time       | 1   | 1   | 0   | 0   |
   Accounting-State              | 0   | 0   | 1   | 0   |
   MIP-Feature-Vector            | 1   | 1   | 0   | 0   |
   MIP-Home-Agent-Address        | 1   | 1   | 0   | 0   |
   MIP-Mobile-Node-Address       | 1   | 1   | 0   | 0   |
   MIP-Previous-FA-Address       | 1   | 1   | 0   | 0   |
   MIP-Previous-FA-FQDN          | 1   | 1   | 0   | 0   |
   ------------------------------|-----+-----+-----+-----+


11.0  Acknowledgements

   The authors would like to thank Nenad Trifunovic, Haseeb Akhtar and
   Pankaj Patel for their participation in the Document Reading Party,
   to Erik Guttman for his very useful proposed text, and to Tony
   Johansson for the proposed text AND being in the doc reading party.
   The authors would also like to thank the participants of 3GPP2's
   TSG-P working group for their valuable feedback.


12.0  IANA Considerations


   This section contains the namespaces that have either been created in
   this specification, or the values assigned to existing namespaces
   managed by IANA.


12.1  Command Codes

   This specification assigns the values 260-263 from the Command Code
   namespace defined in [1], and extended in [9] and [14]. See section
   2.0 for the assignment of the namespace in this specification.


12.2  AVP Codes




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   This specification assigns the values 320-322, 324-329 and 331-346
   from the AVP Code namespace defined in [1], and extended in [9] and
   [14].  See sections 5.0 and 7.0 for the assignment of the namespace
   in this specification.

   This specification also makes use of AVP Code 400, which is assigned
   in [14].


12.3  Result-Code AVP Values

   This specification assigns the values 4004-4006 from the Result-Code
   AVP (AVP Code 268) value namespace defined in [1], and extended in
   [9].  See section 3.0 for the assignment of the namespace in this
   specification.


12.4  DSI-Event AVP Values

   This specification assigns the values 4002-4004 and 5009 from the
   DSI-Event AVP (AVP Code 297) value namespace defined in [1]. See
   section 4.0 for the assignment of the namespace in this
   specification.


12.5  MIP-Feature-Vector AVP Values

   There are 32 bits in the MIP-Feature-Vector AVP (AVP Code 337) that
   are available for assignment. This document assigns bits 1-9, as
   listed in section 5.7. The remaining bits should only be assigned via
   Standards Action [14].


12.6  MIP-Algorithm-Type AVP Values

   As defined in Section 7.2.7, the MIP-Algorithm-Type AVP (AVP Code
   345) defines the values 0-1. All remaining values are available for
   assignment via Designated Expert [14].


12.7  MIP-Replay-Mode AVP Values

   As defined in Section 7.2.8, the MIP-Replay-Mode AVP (AVP Code 346)
   defines the values 0-2. All remaining values are available for
   assignment via Designated Expert [14].


12.8  Extension Identifier



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   This specification assigns the value four (4) to the Extension
   Identifier namespace defined in [1]. See section 1.6 for more
   information.


13.0  Security Considerations

   This specification describes the Diameter extension necessary to
   authenticate and authorize a Mobile IP Mobile Node. The
   authentication algorithm used is dependent upon the transforms
   available by the Mobile IP protocol, and [5]. This specification also
   defines a method by which the home Diameter server can create and
   distribute registration keys to be used to authenticate Mobile IP
   registration messages. The keys are distributed in an encrypted
   format through the Diameter protocol, and SHOULD be encrypted using
   the methods defined in [9].


14.0  References


   [1]  P. Calhoun, A. Rubens, H. Akhtar, E. Guttman, "Diameter Base
        Protocol", draft-ietf-aaa-diameter-03.txt, IETF work in pro-
        gress, May 2001.

   [2]  P. Calhoun, "Diameter Resource Management", draft-calhoun-
        diameter-res-mgmt-06.txt, IETF Work in Progress, February 2001.

   [3]  S. Glass, S. Jacobs, C. Perkins, "Mobile IP Authentication,
        Authorization, and Accounting Requirements". RFC 2977. October
        2000.

   [4]  C. Perkins, Editor. IP Mobility Support. RFC 2002, October 1996.

   [5]  C. Perkins, P. Calhoun, "Mobile IP Challenge/Response Exten-
        sions". RFC 3012. November 2000.

   [6]  B. Aboba, M. Beadles "The Network Access Identifier." RFC 2486.
        January 1999.

   [7]  B. Aboba, G. Zorn, "Criteria for Evaluating Roaming Protocols",
        RFC 2477, January 1999.

   [8]  P. Calhoun, C. Perkins, "Mobile IP Network Address Identifier
        Extension", RFC 2794, March 2000.

   [9]  P. Calhoun, W. Bulley, S. Farrell, "Diameter End-2-End Security
        Extensions", draft-ietf-aaa-diameter-e2e-sec-01.txt, IETF work



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        in progress, May 2001.

   [10] Kent, Atkinson, "IP Encapsulating Security Payload (ESP)", RFC
        2406, November 1998.

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

   [12] F. Yergeau, "UTF-8, a transformation format of ISO 10646", RFC
        2279, January 1998.

   [13] H. Krawczyk, M. Bellare, and R. Cannetti.  HMAC: Keyed-Hashing
        for Message Authentication.  RFC 2104, February 1997.

   [14] P. Calhoun, W. Bulley, A. Rubens, J. Haag, "Diameter NASREQ
        Extension", draft-ietf-aaa-diameter-nasreq-03.txt, IETF work in
        progress, May 2001.

   [15] C. Perkins, P. Calhoun, "AAA Registration Keys for Mobile IP",
        draft-ietf-aaa-mobileip-aaa-key-04.txt, IETF work in progress,
        May 2001.

   [16] T. Hiller and al, "CDMA2000 Wireless Data Requirements for AAA",
        draft-hiller-cdma2000-aaa-01.txt, IETF work in progress, June
        2000.

   [17] Narten, Alvestrand,"Guidelines for Writing an IANA Considera-
        tions Section in RFCs", BCP 26, RFC 2434, October 1998


15.0  Authors' Addresses

   Questions about this memo can be directed to:

      Pat R. Calhoun
      Network and Security Research Center, Sun Labs
      Sun Microsystems, Inc.
      15 Network Circle
      Menlo Park, California, 94025
      USA

       Phone:  +1 650-786-7733
         Fax:  +1 650-786-6445
      E-mail:  pcalhoun@eng.sun.com







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      Charles E. Perkins
      Nokia Research Center
      313 Fairchild Drive
      Mountain View, California 94043
      USA

      Phone:  +1 650-625-2986
        Fax:  +1 650-625-2502
      E-Mail: charliep@iprg.nokia.com


16.0  Full Copyright Statement

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this docu-
   ment itself may not be modified in any way, such as by removing the
   copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of develop-
   ing Internet standards in which case the procedures for copyrights
   defined in the Internet Standards process must be followed, or as
   required to translate it into languages other than English. The lim-
   ited permissions granted above are perpetual and will not be revoked
   by the Internet Society or its successors or assigns. This document
   and the information contained herein is provided on an "AS IS" basis
   and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DIS-
   CLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
   TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
   INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
   FITNESS FOR A PARTICULAR PURPOSE.


17.0  Expiration Date

   This memo is filed as <draft-ietf-aaa-diameter-mobileip-03.txt> and
   expires in October 2001.










Calhoun, Perkins          expires October 2001                 [Page 40]