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AAA Working Group                                         Pat R. Calhoun
Internet-Draft                                      Black Storm Networks
Category: Standards Track                                 Tony Johansson
<draft-ietf-aaa-diameter-mobileip-09.txt>                   Ericsson Inc
                                                      Charles E. Perkins
                                                   Nokia Research Center
                                                              March 2002



                    Diameter Mobile IPv4 Application


Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC 2026.

   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
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

   Distribution of this memo is unlimited.

   Copyright   (C) The Internet Society 2002.  All Rights Reserved.

Abstract

   This document specifies a Diameter application 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-Realm capability of the base protocol, this application
   allows mobile nodes to receive service from foreign service
   providers. Diameter Accounting messages will be used by the Foreign
   and Home agents to transfer usage information to the Diameter
   servers.



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Table of Contents

      1.0  Introduction
            1.1  Requirements language
            1.2  Inter-Realm Mobile IP
            1.3  Support for Mobile IP Handoffs
            1.4  Allocation of Home Agent in Foreign Network
            1.5  Co-located Mobile Node
            1.6  Diameter Session Termination
            1.7  Advertising Application support
            1.8  Fast Handoff support
      2.0  Command-Code Values
            2.1  AA-Mobile-Node-Request
            2.2  AA-Mobile-Node-Answer
            2.3  Home-Agent-MIP-Request
            2.4  Home-Agent-MIP-Answer
      3.0  Result-Code AVP Values
            3.1  Transient Failures
            3.2  Permanent Failures
      4.0  Diameter AVPs
            4.1  MIP-Reg-Request AVP
            4.2  MIP-Reg-Reply AVP
            4.3  MIP-Mobile-Node-Address AVP
            4.4  MIP-Home-Agent-Address AVP
            4.5  MIP-Feature-Vector AVP
            4.6  MIP-MN-AAA-Auth AVP
                  4.6.1  MIP-MN-AAA-SPI AVP
                  4.6.2  MIP-Auth-Input-Data-Length AVP
                  4.6.3  MIP-Authenticator-Length AVP
                  4.6.4  MIP-Authenticator-Offset AVP
            4.7  MIP-FA-Challenge AVP
            4.8  MIP-Foreign-Agent-Host AVP
            4.9  MIP-Filter-Rule AVP
            4.10 MIP-Candidate-Home-Agent-Host
            4.11 MIP-Originating-Foreign-AAA AVP
      5.0  Key Distribution Center
            5.1  Authorization Lifetime vs. MIP Key Lifetime
            5.2  Key Material vs. Session Key
            5.3  Distributing the Mobile-Home Session Key
            5.4  Distributing the Mobile-Foreign Session Key
            5.5  Distributing the Foreign-Home Session Key
            5.6  Key Distribution Example
      6.0  Key Distribution Center (KDC) AVPs
            6.1  MIP-FA-to-MN-Key AVP
            6.2  MIP-FA-to-HA-Key AVP
            6.3  MIP-HA-to-FA-Key AVP
            6.4  MIP-HA-to-MN-Key AVP
            6.5  MIP-MN-to-FA-Key AVP



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            6.6  MIP-MN-to-HA-Key AVP
            6.7  MIP-Session-Key AVP
            6.8  MIP-Algorithm-Type AVP
            6.9  MIP-Replay-Mode AVP
            6.10 MIP-FA-to-MN-SPI
            6.11 MIP-FA-to-HA-SPI
            6.12 MIP-Key-Material AVP
            6.13 MIP-Key-Lifetime AVP
      7.0  Accounting AVPs
            7.1  Accounting-Input-Octets AVP
            7.2  Accounting-Output-Octets AVP
            7.3  Acct-Session-Time AVP
            7.4  Accounting-Input-Packets AVP
            7.5  Accounting-Output-Packets AVP
      8.0  AVP Table
            8.1  Mobile IP Command AVP Table
            8.2  Accounting AVP Table
      9.0  IANA Considerations
            9.1  Command Codes
            9.2  AVP Codes
            9.3  Result-Code AVP Values
            9.4  MIP-Feature-Vector AVP Values
            9.5  MIP-Algorithm-Type AVP Values
            9.6  MIP-Replay-Mode AVP Values
            9.7  Application Identifier
      10.0 Security Considerations
      11.0 References
            11.1  Normative
            11.2  Informative
      12.0  Acknowledgements
      13.0  Authors' Addresses
      14.0  Full Copyright Statement
      15.0  Expiration Date


















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1.0  Introduction

   Mobile IP, as defined in [MOBILEIP], 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 the applicability of Mobile IP in a IPv4 commercial
   deployment.  The Mobile IP specification as defined in [MOBILEIP]
   recommends mobile nodes to have a static home address and a home
   agent. However this may not be always possible in certain deployment
   scenarios. Recent developments in areas that impact IP mobility in
   the IETF allow Mobile IP [MOBILEIP] to work just as well when mobile
   nodes do not have a static home agent and home address. Recent
   specification [MIPNAI] allows a mobile node to use its NAI instead of
   its home address, which better accommodates current administrative
   practice.

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

   Combined with the Inter-Realm capability of the base protocol, this
   application 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 [MOBILEIP] 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
   session 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 application can process users' identities supplied in a
   Network Access Identifier (NAI) format [NAI], which is used for
   Diameter message routing purposes.  Mobile nodes include their NAI in
   Registration messages, as defined in [MIPNAI]. The use of the NAI is
   consistent with the roaming model defined by the ROAMOPS Working
   Group [EVALROAM].






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   An AAA Home server (AAAH) and AAA foreign server (AAAF) which
   supports the Mobile-IP authentication application MAY maintain
   session-state or MAY be session-stateless. AAA redirect agents and
   AAA relay agents MUST not maintain session-state. The AAAH, AAAF,
   proxies and relays agents MUST maintain transaction state.

   Given the nature of Mobile IP, a re-authentication can only be
   initiated by a mobile node, which does not participate in the
   Diameter message exchanges. Therefore the Diameter base protocol's
   server initiated re-auth does not apply to this application

   The Diameter Mobile-IP Application meets the requirements specified
   in [MIPREQ, CDMA2000]. 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" [MIPREQ] is
   performed by either the home agents (for co-located mobile nodes) or
   foreign agents for the Mobile-IP Application, 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
   interpreted as described in [KEYWORDS].

























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1.2  Inter-Realm 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 Realm                    Home Realm
                     +--------+                     +--------+
                     |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-Realm Mobility

   Upon receiving the AMR, the AAAF follows the procedures outlined in
   [DIAMBASE] 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.










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   Figure 2 shows the message flows involved when the foreign agent
   invokes the AAA infrastructure to request that a mobile node be
   authenticated and authorized. Note that it is not required that 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 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------------>
                      Session-Id = foo

                                     AMR------------>
                                     Session-Id = foo

                                                   HAR----------->
                                                   Session-Id = bar

                                                     <----------HAA
                                                   Session-Id = bar

                                       <-----------AMA
                                       Session-Id = foo

                        <------------AMA
                        Session-Id = foo

        <-------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 [MIPCHAL].  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_AUTHENTICATION_REJECTED.





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   In the event that the AMR generated by the FA is for a session that
   has was previously authorized by the AAAH, it MUST include the
   Destination-Host AVP, with the identity of the AAAH. The AAAH's
   identity can be retrieved from the Origin-Host AVP in the last AMA
   received for the session.

   If the Mobile Node was successfully authenticated, the AAAH checks if
   the Home Agent was located in the foreign realm, by checking the
   Home-Agent-In-Foreign-Network flag of the MIP-Feature-Vector AVP.  If
   the flag is enabled, then the Home Agent is located in the foreign
   realm then AAAH sends an HAR message to AAAF which contains a MIP-
   Reg-Request AVP.

   If the Home Agent was not located in the foreign realm, 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, and the Home Agent's
   identity is included in the Destination-Host AVP. 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 realm, 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.

   The AAAH then sends an 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, while the Home
   Agent MUST support home address allocation. In the event the AAAH
   handles address allocation, it includes it in a MIP-Mobile-Node-
   Address AVP within the HAR.  The absence of this AVP informs the Home
   Agent to perform the allocation.

   During the creation of the HAR, the AAAH MUST use a different session
   identifier than the one used in the AMR/AMA (see Figure 2). If the
   AAAH is session-stateful, it should send the same session identifier
   for all HARs initiated on behalf of a given mobile node's session.
   Otherwise, if the AAAH is session-stateless, it will manufacture a
   unique session-id for every HAR.  (Note--This will not cause a
   problem for the HA, who must be able to recognize a handoff even if
   the AAAH thinks the session is new; an AAAH may incorrectly view a
   session as new when the handoff AMR goes to a different AAAH than the
   previous AMR).






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   A mobile node's session is identified via its identity in the User-
   Name AVP, the MIP-Mobile-Node-Address and the MIP-Home-Agent-Address
   AVPs. This is necessary in order to allow the session state machine,
   defined in the base protocol [DIAMBASE], to be used unmodified with
   this application. Therefore, an STR from a foreign agent would free
   the session from the foreign agent, but not the one towards the home
   agent (see figure 3).

           STR, Session-Id = foo       STR, Session-Id = bar
           --------------------->      <--------------------
      +----+      +------+      +------+                    +----+
      | FA |      | AAAF |      | AAAH |                    | HA |
      +----+      +------+      +------+                    +----+
           <---------------------      --------------------->
           STA, Session-Id = foo       STA, Session-Id = bar
            Figure 3: Session Termination and Session Identifiers

   Upon receipt of the HAR, the Home Agent first processes the Diameter
   message. 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 HA MUST include an Accounting-Multi-
   Session-Id AVP in the HAA returned to the AAAH.

   Upon receipt of the HAA, the AAAH creates the AA-Mobile-Node-Answer
   (AMA) message, includes the Accounting-Multi-Session-Id that was
   present in the HAA, and the MIP-Home-Agent-Address, 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  Support for Mobile IP Handoffs

   Given the nature of Mobile IP, a mobile node MAY receive service from
   many foreign agents during a period of time. However, the home realm
   should not view these handoffs as different sessions, since this
   could affect billing systems. Furthermore, many foreign agents do not
   communicate, which makes it quite difficult for AAA information to be
   exchanged between these entities.  Therefore, it MUST be assumed that
   a foreign agent is not aware that a registration request from a
   mobile node has been previously authorized.





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   The first registration request from a mobile node will therefore
   cause an AMR to be sent to its AAAF. The AMR will include a new
   session identifier, and MAY even be sent to a different AAAF in the
   visited network. It is also possible that the AMR will be received by
   a different AAAH.

   Since the new AAAH in the home network MAY not have access to the
   session identifier that was used by the old AAAH, or since the AAAH
   may be session-stateless, it is necessary for the resulting HAR
   received by the HA to be identified as a continuation of an existing
   session. If the HA receives an HAR for a mobile node, with a new
   session identifier, and the HA can guarantee that this request is to
   extend service for an existing service, then the HA MUST be able to
   modify its internal session state information to reflect the
   (possibly) new AAAH and new session identifier.

   If the AAAH is new, the HA MUST also issue an STR message with the
   old session identifier to the AAAH it was communicating with when
   using the old session identifier.

   It is necessary for accounting records to have some commonality
   across handoffs in order for correlation to occur.  Therefore, the
   home agent MUST send the same Accounting-Multi-Session-Id AVP value
   in all HAAs for the mobile's session.  That is, the HA generates a
   unique Accounting-Multi-Session-Id when receiving an HAR for a new
   session, and returns this same value in every HAA for the session.
   This Accounting-Multi-Session-Id AVP will be returned to the foreign
   agent by the AAAH in the AMA. Both the foreign and home agents MUST
   include the Accounting-Multi-Session-Id in the accounting messages.



           ACR, Session-Id = foo         ACR, Session-Id = bar
       Accounting-Multi-Session-Id = a   Accounting-Multi-Session-Id = a
           --------------------->      <--------------------
      +----+      +------+      +------+                    +----+
      | FA |      | AAAF |      | AAAH |                    | HA |
      +----+      +------+      +------+                    +----+
           <---------------------      --------------------->
           ACA, Session-Id = foo       ACA, Session-Id = bar

            Figure 4: Accounting messages w/ Mobile IP Application









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1.4  Allocation of Home Agent in Foreign Network

   The Diameter Mobile IP application allows a Home Agent to be
   allocated in a foreign network, as required in [MIPREQ, CDMA2000].
   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-Realm 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-Realm flag equal to zero.

   When the AAAF receives an AMR message with the Home-Agent-Requested
   flag set to one, and the Home-Address-Allocatable-Only-in-Home-Realm
   flag equal to zero, the 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. When
   doing so, the AAAF MUST include the MIP-Candidate-Home-Agent-Host AVP
   and the MIP-Originating-Foreign-AAA-AVP. The MIP-Candidate-Home-
   Agent-Host AVP contains the identity of the home agent that would be
   assigned to the mobile node and the MIP-Originating-Foreign-AAA AVP
   contains the identity of the AAAF.

   In the event that the mobile node requests a home agent in the
   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 an 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 Home Agent found in the AMR's MIP-Candidate-Home-
   Agent-Host AVP. The HAR message does not in this case contain the
   MIP-Home-Agent- Address, but includes the Destination-Host AVP set to
   the value in the MIP-Candidate-Home-Agent-Host AVP.









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   If the HA hasn't yet been allocated by the foreign domain, the HAR
   sent by the AAAH back to the foreign realm will not necessarily be
   received by the same AAAF which sent the AMR. Therefore the AAAH MUST
   always copy the MIP-Originating-Foreign-AAA AVP from the AMR message
   to the HAR message. In cases when another AAAF, which may not reside
   in the same domain, receives the HAR, thus the new AAAF will use the
   MIP-Originating-Foreign-AAA AVP for policy decisions, such as
   determining if the FA-HA Key should be encrypted or not.

                           Visited                           Home
                            Realm                           Realm
                          +--------+ ------- AMR -------> +--------+
                          |  AAAF  | <------ HAR -------- |  AAAH  |
                          |        |                      |        |
                     +--->| server | ------- HAA -------> | server |
                     |    +--------+ <------ AMA -------- +--------+
                     |         ^  |
                     |         |  |
             HAR/HAA |     AMR |  | AMA
                     v         |  v
             +---------+       +---------+
             |   Home  |       | Foreign |
             |  Agent  |       |  Agent  |
             +---------+       +---------+
                                       ^
                  +--------+           |
                  | Mobile |<----------+
                  | Node   |  Mobile IP
                  +--------+
              Figure 5: Home Agent allocated in Visited Realm

   Upon receipt of a HAA from the Home Agent in the visited realm, the
   AAAF forwards the HAA to the AAAH in the home realm. The AMA is then
   constructed, and issued to the AAAF, and finally to the FA. If the
   Result-Code indicates success, 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 6: 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 7 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 the identity of the
   foreign and home agent to determine whether the user is in a third
   realm. If this is the case, the AAAH must check whether the mobile is
   still permitted to 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 7: 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 HAA, the AAAF will forward the HAA back to
   the AAAH.  If successful, 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 Abort-Session-
   Request message to the Home Agent to enable it to release any
   resources.






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1.5  Co-located Mobile Node

   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. The Home Agent
   also includes the Accounting-Multi-Session-Id AVP in the AMR sent to
   the AAAH, as the AAAH may find this a useful piece of session-state
   or log entry information.

                                          Home
                                         Realm
                                       +--------+
                                       |  AAAH  |
                                       |        |
                                       | server |
                                       +--------+
                                         ^  |
                                         |  |
                                     AMR |  | AMA
                                         |  v
             +--------+               +---------+
             | Mobile | Registration  |  Home   |
             | Node   |-------------->|  Agent  |
             +--------+    Request    +---------+
                     Figure 8: 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.



1.6  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) to the Diameter server that authorized the service. The
   Session-Termination-Request (STR) MUST be issued by the mobility
   agents if the Authorization Lifetime has expired and no subsequent
   MIP registration request have been received.






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   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.

   In the event that the AAAF wishes to terminate a session, its Abort-
   Session-Request (ASR) [DIAMBASE] message SHOULD be sent to the FA.
   Similarly, the AAAH SHOULD send its message to the Home Agent.

1.7  Advertising application support

   Diameter nodes conforming to this specification MAY advertise support
   by including the value of four (4) in the Auth-Application-Id or the
   Acct-Application-Id AVP of the Capabilities-Exchange-Request and
   Capabilities-Exchange-Answer command [DIAMBASE].


1.8  Fast Handoff support

   This application requires that foreign agents issue an AMR upon
   receipt of the first registration message from a mobile node,
   regardless of the fact that the mobile node MAY have been previously
   authorized to another foreign agent.

   The Mobile IP Working Group is currently investigating fast handoff
   proposals, and the Seamoby WG is looking at creating a protocol that
   would allow AAA state information to be exchange between foreign
   agents during a handoff. These proposals MAY allow future
   enhancements to the Diameter protocol, in order to reduce the amount
   of Diameter exchanges required during a handoff.


2.0  Command-Code Values

   This section defines Command-Code [DIAMBASE] 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         260          2.2
      AA-Mobile-Node-Request       AMR         260          2.1
      Home-Agent-MIP-Answer        HAA         262          2.4
      Home-Agent-MIP-Request       HAR         262          2.3





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2.1  AA-Mobile-Node-Request

   The AA-Mobile-Node-Request (AMR), indicated by the Command-Code field
   set to 260 and the 'R' bit set in the Command Flags field, 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 [DIAMBASE]).
          MN-HA Key Request (MIP-Feature-Vector AVP)
          MN-FA Key Request (MIP-Feature-Vector AVP)
          MN-AAA Authentication Extension (MIP-MN-AAA-Auth AVP)
          Foreign Agent Challenge Extension (MIP-FA-Challenge 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 realm.

   If the mobile node's home address is all ones, the foreign or home
   agent MUST include a MIP-Mobile-Node-Address AVP, set to all ones.





















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   Message Format

      <AA-Mobile-Node-Request> ::= < Diameter Header: 260, REQ, PXY >
                                   < Session-ID >
                                   { Auth-Application-Id }
                                   { User-Name }
                                   { Destination-Realm }
                                   { Origin-Host }
                                   { Origin-Realm }
                                   { MIP-Reg-Request }
                                   { MIP-MN-AAA-Auth }
                                   [ Destination-Host ]
                                   [ Origin-State-Id ]
                                   [ MIP-Mobile-Node-Address ]
                                   [ MIP-Home-Agent-Address ]
                                   [ MIP-Feature-Vector ]
                                   [ MIP-Originating-Foreign-AAA ]
                                   [ Authorization-Lifetime ]
                                   [ Auth-Grace-Period ]
                                   [ Auth-Session-State ]
                                   [ MIP-FA-Challenge ]
                                   [ MIP-Candidate-Home-Agent-Host ]
                                 * [ AVP ]
                                 * [ Proxy-Info ]
                                 * [ Route-Record ]


2.2  AA-Mobile-Node-Answer

   The AA-Mobile-Node-Answer (AMA), indicated by the Command-Code field
   set to 260 and the 'R' bit cleared in the Command Flags field, is
   sent by the AAAH in response to the AA-Mobile-Node-Request message.
   The User-Name MAY be included in the AMA if present in the AMR. The
   Result-Code AVP MAY contain one of the values defined in section 3.0,
   in addition to the values defined in [DIAMBASE].

   An AMA message with the Result-Code AVP set to DIAMETER_SUCCESS MUST
   include the MIP-Home-Agent-Address AVP, MUST include the MIP-Home-
   Mobile-Node-Address AVP, and includes the MIP-Reg-Reply AVP if and
   only if the Co-Located-Mobile-Node bit was not set in the MIP-
   Feature-Vector 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. The AMA message MUST
   contain the MIP-FA-to-HA-Key, MIP-FA-to-MN-Key if they were requested
   in the AMR, and they were present in the HAR. The MIP-MN-to-HA-Key
   and MIP-HA-to-MN-Key AVPs MUST be present if the session keys were
   requested in the AMR, and the Co-Located-Mobile-Node bit was set in
   the MIP-Feature-Vector AVP.



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   An AMA message with the Result-Code AVP set to
   DIAMETER_LIMITED_SUCCESS MAY include the MIP-Home-Agent-Address AVP
   if a dynamically assigned home agent was requested by the mobile
   node. Upon receipt of this result code, the foreign agent MUST issue
   the Registration Request to the Home Agent in the manner described in
   [MOBILEIP].

   An AMA message with the Result-Code set to DIAMETER_MULTI_ROUND_AUTH
   MAY include mobile node session key AVPs (see Section 6.1) such as
   the MIP-MN-to-FA-Key AVP and the MIP-MN-to-HA-Key AVP. If such an AVP
   is present in the AMA message, the foreign agent MUST include the
   corresponding Mobile IP key distribution extension in the
   Registration Reply it sends to the mobile node. This is to support
   multi-roundtrip authentication mechanisms.





































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   Message Format

      <AA-Mobile-Node-Answer> ::= < Diameter Header: 260, PXY >
                                  < Session-Id >
                                  { Auth-Application-Id }
                                  { Result-Code }
                                  { Origin-Host }
                                  { Origin-Realm }
                                  [ User-Name ]
                                  [ Accounting-Multi-Session-Id ]
                                  [ Authorization-Lifetime ]
                                  [ Auth-Grace-Period ]
                                  [ Auth-Session-State ]
                                  [ Error-Message ]
                                  [ Error-Reporting-Host ]
                                  [ Re-Auth-Request-Type ]
                                  [ MIP-Feature-Vector ]
                                  [ MIP-Reg-Reply ]
                                  [ MIP-MN-to-FA-Key ]
                                  [ MIP-MN-to-HA-Key ]
                                  [ MIP-FA-to-MN-Key ]
                                  [ MIP-FA-to-HA-Key ]
                                  [ MIP-HA-to-MN-Key ]
                                  [ MIP-HA-to-FA-Key ]
                                  [ MIP-Key-Lifetime ]
                                  [ MIP-Home-Agent-Address ]
                                  [ MIP-Mobile-Node-Address ]
                                * [ MIP-Filter-Rule ]
                                  [ Session-Timeout ]
                                  [ Origin-State-Id ]
                                * [ AVP ]
                                * [ Proxy-Info ]


2.3  Home-Agent-MIP-Request

   The Home-Agent-MIP-Request (HAR), indicated by the Command-Code field
   set to 262 and the 'R' bit set in the Command Flags field, 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 session keys are requested for use by the mobile node (see



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   section 5.0), the AAAH MUST create them and include them in the HAR
   message.  When a Foreign-Home session key is requested, it will be
   created and distributed by the AAA server in the same realm as the
   home agent.

   Message Format

      <Home-Agent-MIP-Request> ::= < Diameter Header: 262, REQ, PXY >
                                   < Session-Id >
                                   { Auth-Application-Id }
                                   { Authorization-Lifetime }
                                   { Auth-Grace-Period }
                                   { Auth-Session-State }
                                   { MIP-Reg-Request }
                                   { Origin-Host }
                                   { Origin-Realm }
                                   { User-Name }
                                   { Destination-Realm }
                                   { MIP-Foreign-Agent-Host }
                                   { MIP-Feature-Vector }
                                   [ Destination-Host ]
                                   [ MIP-MN-to-HA-Key ]
                                   [ MIP-MN-to-FA-Key ]
                                   [ MIP-HA-to-MN-Key ]
                                   [ MIP-HA-to-FA-Key ]
                                   [ MIP-Key-Lifetime ]
                                   [ MIP-Originating-Foreign-AAA ]
                                   [ MIP-Mobile-Node-Address ]
                                   [ MIP-Home-Agent-Address ]
                                 * [ MIP-Filter-Rule ]
                                   [ Session-Timeout ]
                                   [ Origin-State-Id ]
                                 * [ AVP ]
                                 * [ Proxy-Info ]
                                 * [ Route-Record ]


2.4  Home-Agent-MIP-Answer

   The Home-Agent-MIP-Answer (HAA), indicated by the Command-Code field
   set to 262 and the 'R' bit cleared in the Command Flags field, is
   sent by the Home Agent to its local AAA server in response to a Home-
   Agent-MIP-Request. The User-Name MAY be included in the HAA if
   present in the HAR. 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 [DIAMBASE].




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   Message Format

      <Home-Agent-MIP-Answer> ::= < Diameter Header: 262, PXY >
                                  < Session-Id >
                                  { Auth-Application-Id }
                                  { Result-Code }
                                  { Origin-Host }
                                  { Origin-Realm }
                                  { MIP-Foreign-Agent-Host }
                                  { Accounting-Multi-Session-Id }
                                  [ User-Name ]
                                  [ Error-Reporting-Host ]
                                  [ Error-Message ]
                                  [ MIP-Reg-Reply ]
                                  [ MIP-Home-Agent-Address ]
                                  [ MIP-Mobile-Node-Address ]
                                  [ MIP-FA-to-HA-SPI ]
                                  [ MIP-FA-to-MN-SPI ]
                                  [ Origin-State-Id ]
                                * [ AVP ]
                                * [ Proxy-Info ]


3.0  Result-Code AVP Values

   This section defines new Result-Code [DIAMBASE] 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_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
         this time. The Foreign Agent MUST return a Mobile IP
         Registration Reply to the Mobile Node with an appropriate error
         code.





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      DIAMETER_ERROR_BAD_KEY             4007
         This error code is used by the Home Agent to indicate to the
         local Diameter server that the key generated is invalid.


3.2  Permanent Failures

   Errors that fall within the permanent failures category are used to
   inform the peer that the request failed, and should not be attempted
   again.

      DIAMETER_ERROR_NO_FOREIGN_HA_SERVICE 5024
         This error is used by the AAAF to inform the AAAH that
         allocation of a Home Agent in the Foreign Domain is not
         permitted at this time.


4.0  Mandatory AVPs

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

   Due to space constraints, the short form IPFiltrRule is used to
   represent IPFilterRule and DiamIdent is used to represent
   DiameterIdentity.

























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                                            +---------------------+
                                            |    AVP Flag rules   |
                                            |----+-----+----+-----|----+
                   AVP  Section             |    |     |SHLD| MUST|MAY |
   Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
   -----------------------------------------|----+-----+----+-----|----|
   MIP-Filter-Rule  342  4.9     IPFiltrRule| M  |  P  |    |  V  | Y  |
   MIP-Auth-Input-  338  4.6.2   Unsigned32 | M  |  P  |    |  V  | Y  |
     Data-Length                            |    |     |    |     |    |
   MIP-             339  4.6.3   Unsigned32 | M  |  P  |    |  V  | Y  |
     Authenticator-Length                   |    |     |    |     |    |
   MIP-             340  4.6.4   Unsigned32 | M  |  P  |    |  V  | Y  |
     Authenticator-Offset                   |    |     |    |     |    |
   MIP-Candidate-   336  4.10    DiamIdent  | M  |  P  |    |  V  | N  |
     Home-Agent-Host                        |    |     |    |     |    |
   MIP-FA-Challenge 344  4.7     OctetString| M  |  P  |    |  V  | Y  |
   MIP-Feature-     337  4.5     Unsigned32 | M  |  P  |    |  V  | Y  |
     Vector                                 |    |     |    |     |    |
   MIP-Foreign-     330  4.8     DiamIdent  | M  |  P  |    |  V  | Y  |
     Agent-Host                             |    |     |    |     |    |
   MIP-Home-Agent-  334  4.4     IPAddress  | M  |  P  |    |  V  | Y  |
     Address                                |    |     |    |     |    |
   MIP-MN-AAA-Auth  322  4.6     Grouped    | M  |  P  |    |  V  | Y  |
   MIP-MN-AAA-SPI   341  4.6.1   Unsigned32 | M  |  P  |    |  V  | Y  |
   MIP-Mobile-Node- 333  4.3     IPAddress  | M  |  P  |    |  V  | Y  |
     Address                                |    |     |    |     |    |
   MIP-Reg-Request  320  4.1     OctetString| M  |  P  |    |  V  | Y  |
   MIP-Reg-Reply    321  4.2     OctetString| M  |  P  |    |  V  | Y  |
   MIP-Originating- 347  4.11    Grouped    | M  |  P  |    |  V  | Y  |
   Foreign-AAA                              |    |     |    |     |    |

4.1  MIP-Reg-Request AVP

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

4.2  MIP-Reg-Reply AVP

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

4.3  MIP-Mobile-Node-Address AVP

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




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4.4  MIP-Home-Agent-Address AVP

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


4.5  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-Realm
         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-
   Realm 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-
   Realm flag in the MIP-Feature-Vector AVP.






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   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
   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
   [MIPKEYS] extension, with the subtype set to AAA.

   If the mobile node includes a Generalized MN-FA Key Request [MIPKEYS]
   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
   either by setting the home address field to all ones, or by
   specifying a home agent in the foreign network, 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 and Home-Agent-In-Foreign-Network
   flags 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.














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4.6  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 [MOBILEIP] by the target AAA
   server.  Its value has the following ABNF grammar:

      MIP-MN-AAA-Auth ::= < AVP Header: 322 >
                          { MIP-MN-AAA-SPI }
                          { MIP-Auth-Input-Data-Length }
                          { MIP-Authenticator-Length }
                          { MIP-Authenticator-Offset }
                        * [ AVP ]


4.6.1  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.


4.6.2  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.


4.6.3  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).


4.6.4  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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4.7   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.


4.8  MIP-Foreign-Agent-Host AVP

   The MIP-Foreign-Agent-Host AVP (AVP Code 330) is of type
   DiameterIdentity and contains the identity of the foreign agent. This
   AVP is copied from the value of the Origin-Host AVP in the AMR.


4.9  MIP-Filter-Rule AVP

   The MIP-Filter-Rule AVP (AVP Code 342) is of type IPFilterRule, 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.


4.10 MIP-Candidate-Home-Agent-Host

   The MIP-Candidate-Home-Agent-Host AVP (AVP Code 336) is of type
   DiameterIdentity and contains the identity of a home agent in the
   foreign network that the AAAF proposes be dynamically assigned to the
   mobile node.


4.11 MIP-Originating-Foreign-AAA AVP

   The MIP-Originating-Foreign-AAA AVP (AVP Code 347) if of type
   Grouped, and contains the identity of the AAAF, which issues the AMR
   to the AAAH. The MIP- Originating-Foreign-AAA AVP MUST only be used
   in cases when the home agent is or may be allocated in a foreign
   domain. If present in the AMR, the AAAH MUST copy the MIP-
   Originating-Foreign-AAA AVP into the HAR.

      MIP-Originating-Foreign-AAA ::= < AVP Header: 347 >
                                       { Origin-Realm }
                                       { Origin-Host }
                                     * [ AVP ]







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5.0  Key Distribution Center

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

   If the AAAH does not communicate directly with the foreign agent, and
   it does not wish for intermediate proxies to have access to the
   session keys, they SHOULD be protected using the CMS security
   application [CMS].

   The SPI values are used as key identifiers, meaning that each session
   key has its own SPI value; nodes that share a key also share an SPI.
   The Mobile Node proposes SPIs for use in computing the Mobile-Foreign
   and Mobile-Home authentication extensions, via the Mobile IP AAA Key
   Request extensions [MIPKEYS], while the Home Agent allocates the
   Mobile-Foreign, Mobile-Home and Foreign-Home SPIs.

   Once the session 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.

5.1 Authorization Lifetime vs. MIP Key Lifetime

   The Diameter Mobile IP application makes use of two timers - the
   Authorization-Lifetime AVP [DIAMBASE] and the MIP-Key-Lifetime AVP.

   The Authorization-Lifetime contains the number of seconds before the
   Mobile Node must issue a subsequent MIP registration request. The
   content of the Authorization-Lifetime AVP corresponds to the Lifetime
   field in the MIP header [MOBILEIP].

   The MIP-Key-Lifetime AVP contains the number of seconds before
   session keys destined for the Mobility Agents and the Mobile Node
   expire. A value of zero indicates infinity (no timeout). If not zero,
   the value of the MIP-Key-Lifetime AVP MUST be at least equal to the
   value in the Authorization Lifetime AVP.







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5.2  Key Material vs. Session Key

   Each session key that is generated by the AAAH will generally be
   distributed to two parties; for instance, a Mobile-Foreign is sent to
   both the mobile node and the foreign agent.

   The key sent to the mobile node is always in the form of key
   material, which the AAAH does by generating a random [RANDOM] value
   of at least 64 bits. The random value is used by the mobile node to
   create the actual session key. The following is an example of a
   session creation procedure, using MD5 as the hashing algorithm.
   Additional algorithms are supported, and listed in [MIPKEYS].

      MD5(AAA-Key | key material | node-address | AAA-Key)

      Where:

         - AAA-Key is the long term secret shared between the mobile
           node and the AAAH.
         - Key material is a random [RANDOM] value of at least 64 bits.
         - node-address is the mobile node's identity. This is the
           contents of the MIP-Mobile-Node-Address AVP, unless the value
           of the AVP is all zero or ones, in which case of value of the
           User-Name AVP is used instead.

   The AAAH then generates the session key, which is destined for the
   mobility agent, in this case the foreign agent, by following the
   above procedures. It is important that the hashing algorithm used by
   the mobile node to construct the session key is the same as the one
   used by the AAAH in the session key generation procedure. The AAAH
   therefore indicates the algorithm used along with the key material.
   The session keys destined for mobility agents may be encoded using
   the security association available between the AAA server and the
   agents (e.g. IPSec, TLS, CMS).

   The Foreign-Home session key is shared between two mobility agents:
   the FA and HA. Since this key is not destined for the mobile node,
   there is no need to follow the session key generation procedures
   detailed above. Instead, the AAAH generates a random [RANDOM] value
   of at least 64 bits for use as the Foreign-Home session key.

   See sections 6.0 for details about the format of the AVPs used to
   transport the session keys.








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5.3  Distributing the Mobile-Home Session Key

   If the mobile node does not have a Mobile-Home session 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 session
   key, and encode it for eventual consumption by the mobile node and
   home agent.

   If the home agent is in the home realm, then AAAH can directly encode
   the Mobile-Home session 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 realm, the AAAH transmits the HAR to the foreign home agent,
   where, prior to delivery to the home agent, it is perused by the AAAF
   hosting the 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 [MOBILEIP].  For this purpose, AAAH encodes
   the Mobile-Home session key material 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 keying information into a Mobile IP
   Generalized MN-HA Key Reply extension [MIPKEYS] in the Registration
   Reply message, using the SPI proposed by the Mobile Node in the MN-HA
   Key Request From AAA Subtype extension. 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 HAA's
   MIP-Reg-Reply AVP.

   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 the foreign agent. The foreign agent can then use
   that AVP to recreate a Registration Reply message, containing the
   Generalized MN-HA Key Reply extension, for delivery to the mobile
   node.

   In summary, the AAAH generates the Mobile-Home key material, which is
   added to the MIP-MN-to-HA-Key AVP. The key material is then used to
   compute the home agent's session key as specified in [MIPKEYS], which
   is then added to the MIP-HA-to-MN-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 key material from the MIP-MN-to-



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   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 session 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.


5.4  Distributing the Mobile-Foreign Session Key

   The Mobile-Foreign session key material is also generated by AAAH
   (upon request) and is added to the 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 [MIPKEYS] to the Mobile IP Registration Reply
   message, using the SPI proposed by the Mobile Node in the MN-FA Key
   Request From AAA Subtype extension. Further, the home agent includes
   the SPI in the HAA's MIP-FA-to-MN-SPI AVP. The AAAH includes the
   session key in the MIP-FA-to-MN-Key AVP in the HAA, which contains
   the session key used by the foreign agent in the computation of the
   Mobile-Foreign authentication extension.

   Upon receipt of the HAA, the Diameter server responsible for key
   allocation creates the MIP-FA-to-HA Key AVP, using the SPI in the
   MIP-FA-to-HA-SPI. If the key is generated at the AAAF (home agent in
   foreign domain), it adds the MIP-FA-to-HA Key AVP to the HAA and
   sends it to the AAAH. Depending upon where the HA was located the
   AAAH either generates the MIP-FA-to-HA Key AVP itself or extracts the
   AVP from the HAA sent by the AAAF. The AAAH adds the MIP-FA-to-HA Key
   to the AMA.  If the MIP-FA-to-MN-Key AVP was present in the AMA, the
   foreign agent MUST include the Mobile-Foreign authentication
   extension in the Registration Reply, using the newly distributed key.


5.5  Distributing the Foreign-Home Session Key

5.5.1 Home Agent in the home network

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

   In the cases when the AAAH generates the Foreign-Home session key,
   the AAAH includes the session key in the MIP-HA-to-FA-Key AVP, and
   includes the AVP as part of the HAR message sent to the home agent.
   The corresponding session key and algorithm that is to be sent to the
   foreign agent is cached in the AAAH until the HAA is received.





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   Upon receipt of the HAR, the home agent recovers the Foreign-Home
   session key, allocates an SPI to be used with the key. The allocated
   SPI is included in the HAA's MIP-FA-to-HA SPI AVP.

   Upon receipt of the HAA, the AAAH adds the MIP-FA-to-HA Key AVP,
   using the SPI in the MIP-FA-to-HA-SPI, and includes the AVP in the
   AMA.

5.5.2 Home Agent in foreign network

   In the cases when the AAAF generates the Foreign-Home session key
   (home agent in foreign domain), the AAAF will, upon receipt of the
   HAR message, generate the Foreign-Home session key and include the
   session key in the MIP-HA-to-FA-Key AVP as part of the HAR message
   forwarded to the home agent. The corresponding session key and
   algorithm that is to be sent to the foreign agent is cached in the
   AAAF until the HAA is received.

   Upon receipt of the HAA, the AAAF creates the MIP-FA-to-HA Key AVP,
   using the SPI in the MIP-FA-to-HA-SPI. The AAAF then checks if the
   Foreign-Home session key destined for the foreign agent needs to be
   encrypted.

   If the session key needs to be encrypted, the AAAF will check if a
   security association can be established using DSA messages defined in
   the CMS application [CMS] with the originating host found in the MIP-
   Originating-Foreign-AAA AVP. If the DSA establishment is successful,
   the AAAF will encrypt the MIP-FA-to-HA Key AVP in a CMS-Encrypted-
   Data AVP with the AAAF as originator and the recipient copied from
   the MIP-Originating-Foreign-AAA AVP. This CMS-Encrypted-Data AVP is
   included by the AAAF in the HAA destined for the AAAH. Otherwise, if
   the DSA establishment fails, the AAAF MUST return a Result-Code AVP
   with DIAMETER_ERROR_NO_FOREIGN_HA_SERVICE.

   If the session key does not need to be encrypted, the AAAF will add
   MIP-FA-to-HA Key to the HAA, upon reception from the HA and forward
   the HAA to the AAAH.

   In either case, the AAAF removes the MIP-FA-to-HA-SPI AVP from the
   HAA returned to the AAAH.

   Upon reception of the HAA, the AAAH MUST copy either the MIP-FA-to-HA
   Key AVP if present or the CMS-Ecrypted-data AVP if present and not
   destined for the AAAH into the AMA.

   If a Foreign-Home session key was present in the AMA, the foreign
   agent MUST include the Mobile-Foreign authentication extension in the
   Registration Reply, using the newly distributed key.



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5.6  Key Distribution Example

   Figure 9 provides an example of subsequent Mobile IP message
   exchange, assuming that AAAH distributed session 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 9: Mobile IP Message Exchange


6.0  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 Session Keys, and that these keys be
   distributed to the three mobile entities, via the Diameter Protocol.
   AAA servers supporting the Diameter Mobile IP Application MUST
   implement the KDC AVPs defined in this document. In other words, AAA
   servers MUST be able to create three session keys: the Mobile-Home,
   Mobile-Foreign, and Foreign-Home keys.

   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
   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 session keys is
   required, it is recommended that the CMS security application [CMS]
   be used.

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





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                                             +---------------------+
                                             |    AVP Flag rules   |
                                             |----+-----+----+-----|----+
                    AVP  Section             |    |     |SHLD| MUST|MAY |
    Attribute Name  Code Defined  Value Type |MUST| MAY | NOT|  NOT|Encr|
    -----------------------------------------|----+-----+----+-----|----|
    MIP-Algorithm-   345  6.8     Enumerated | M  |  P  |    |  V  | Y  |
      Type                                   |    |     |    |     |    |
    MIP-FA-to-HA-Key 328  6.2     Grouped    | M  |  P  |    |  V  | Y  |
    MIP-FA-to-HA-SPI 318  6.11    Unsigned32 | M  |  P  |    |  V  | Y  |
    MIP-FA-to-MN-Key 326  6.1     Grouped    | M  |  P  |    |  V  | Y  |
    MIP-FA-to-MN-SPI 319  6.10    Unsigned32 | M  |  P  |    |  V  | Y  |
    MIP-HA-to-FA-Key 329  6.3     Grouped    | M  |  P  |    |  V  | Y  |
    MIP-HA-to-MN-Key 332  6.4     Grouped    | M  |  P  |    |  V  | Y  |
    MIP-Key-Lifetime 367  6.13    Unsigned32 | M  |  P  |    |  V  | Y  |
    MIP-Key-Material 335  6.12    OctetString| M  |  P  |    |  V  | Y  |
    MIP-MN-to-FA-Key 325  6.5     Grouped    | M  |  P  |    |  V  | Y  |
    MIP-MN-to-HA-Key 331  6.6     Grouped    | M  |  P  |    |  V  | Y  |
    MIP-Replay-Mode  346  6.9     Enumerated | M  |  P  |    |  V  | Y  |
    MIP-Session-Key  343  6.7     OctetString| M  |  P  |    |  V  | Y  |


6.1  MIP-FA-to-MN-Key AVP

   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 Data field has the following ABNF grammar:

      MIP-FA-to-MN-Key ::= < AVP Header: 326 >
                           { MIP-FA-to-MN-SPI }
                           { MIP-Algorithm-Type }
                           { MIP-Session-Key }
                         * [ AVP ]


6.2  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 Data field has the following ABNF grammar:

      MIP-FA-to-HA-Key ::= < AVP Header: 328 >
                           { MIP-FA-to-HA-SPI }
                           { MIP-Algorithm-Type }
                           { MIP-Session-Key }
                         * [ AVP ]





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6.3  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 Data field has the following ABNF grammar:

      MIP-HA-to-FA-Key ::= < AVP Header: 329 >
                           { MIP-Algorithm-Type }
                           { MIP-Session-Key }
                         * [ AVP ]


6.4  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 Data field has the following ABNF grammar:

      MIP-HA-to-MN-Key ::= < AVP Header: 332 >
                           { MIP-Algorithm-Type }
                           { MIP-Replay-Mode }
                           { MIP-Session-Key }
                         * [ AVP ]


6.5  MIP-MN-to-FA-Key AVP

   The MIP-MN-to-FA-Key AVP (AVP Code 325) is of type Grouped, and
   contains the Mobile Node's key material, which it uses to derive the
   session key it shares with the Foreign Agent. The Home Agent uses
   this AVP in the construction of the Mobile IP "Unsolicted MN-FA Key
   from AAA Subtype" extension [MIPKEYS]. The SPI in the extension's FA
   SPI field is allocated by the Home Agent, but it SHOULD take into
   consideration the SPI requested by the Mobile Node in the "MN-FA Key
   Request From AAA Subtype" extension.

      MIP-MN-to-FA-Key ::= < AVP Header: 325 >
                           { MIP-Algorithm-Type }
                           { MIP-Key-Material }
                           { MIP-MN-AAA-SPI }
                         * [ AVP ]










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6.6  MIP-MN-to-HA-Key AVP

   The MIP-MN-to-HA-Key AVP (AVP Code 331) is of type Grouped, and
   contains the Mobile Node's  key material, which it uses to derive the
   session key it shares with the Home Agent. The Home Agent uses this
   AVP in the construction of the Mobile IP "Unsolicted MN-HA Key from
   AAA Subtype" extension [MIPKEYS]. The SPI in the extension's HA SPI
   field is allocated by the Home Agent, but it SHOULD take into
   consideration the SPI requested by the Mobile Node in the "MN-HA Key
   Request From AAA Subtype" extension.

      MIP-MN-to-HA-Key ::= < AVP Header: 331 >
                           { MIP-Algorithm-Type }
                           { MIP-Replay-Mode }
                           { MIP-Key-Material }
                           { MIP-MN-AAA-SPI }
                         * [ AVP ].fi


6.7  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.


6.8  MIP-Algorithm-Type AVP

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

      1   Prefix+Suffix MD5 [MOBILEIP]
      2   HMAC-MD5 [HMAC]
      3   HMAC-SHA-1 [HMAC]















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6.9  MIP-Replay-Mode AVP

   The MIP-Replay-Mode AVP (AVP Code 346) is of type Enumerated and
   contains the replay mode the Home Agent should use when
   authenticating the Mobile Node.

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

      1   None
      2   Timestamps
      3   Nonces


6.10  MIP-FA-to-MN-SPI AVP

   The MIP-FA-to-MN-SPI AVP (AVP Code 319) is of type Unsigned32, and
   contains the Security Parameter Index the Foreign Agent is to use to
   refer to the session key it shares with the Mobile Node. The SPI
   created MUST NOT be a value between zero (0) and 255, which is the
   reserved namespace defined in [MOBILEIP]. This AVP MAY be added in
   the HAA message by the Home Agent for the AAAH's use in MIP-FA-to-MN-
   SPI AVP of the MIP-FA-to-MN-Key AVP.


6.11  MIP-FA-to-HA-SPI AVP

   The MIP-FA-to-HA-SPI AVP (AVP Code 318) is of type Unsigned32, and
   contains the Security Parameter Index the Foreign Agent is to use to
   refer to the session key it shares with the Home Agent. The SPI
   created MUST NOT be a value between zero (0) and 255, which is the
   reserved namespace defined in [MOBILEIP]. If FA-HA keys are being
   generated, this AVP MUST be added in the HAA message by the Home
   Agent for the AAAH's (or AAAF's) use in providing the value of the
   MIP-FA-to-HA-SPI member of the grouped MIP-FA-to-HA-Key AVP.


6.12  MIP-Key-Material AVP

   The MIP-Key-Material AVP (AVP Code 335) is of type OctetString and
   contains the key material sent to the mobile node. The mobile node
   follows the procedures in [MIPKEYS] to generate the session key used
   to authenticate Mobile IP registration messages.








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6.13  MIP-Key-Lifetime AVP

   The MIP-Key-Lifetime AVP (AVP Code 367) is of type Unsigned32 and
   represents the period of time (in seconds) for which the session key
   is valid.  The session key MUST NOT be used if the lifetime has
   expired; if the key lifetime expires while the session to which it
   applies is still active, either the session key MUST be changed or
   the or the session MUST be terminated.


7.0  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.


7.1  Accounting-Input-Octets AVP

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


7.2  Accounting-Output-Octets AVP

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


7.3  Acct-Session-Time AVP

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


7.4  Accounting-Input-Packets AVP

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


7.5  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.



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8.0  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.


8.1  Mobile IP Command AVP Table

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































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                                 +-----------------------+
                                 |      Command-Code     |
                                 |-----+-----+-----+-----+
   Attribute Name                | AMR | AMA | HAR | HAA |
   ------------------------------|-----+-----+-----+-----+
   Authorization-Lifetime        | 0-1 | 0-1 | 1   | 0   |
   Auth-Application-Id           | 1   | 1   | 1   | 1   |
   Auth-Grace-Period             | 0-1 | 0-1 | 1   | 0   |
   Auth-Session-State            | 0-1 | 0-1 | 1   | 0   |
   Accounting-Multi-Session-Id   | 0-1 | 1   | 0   | 1   |
   Destination-Host              | 0-1 | 0   | 0-1 | 0   |
   Destination-Realm             | 1   | 0   | 1   | 0   |
   Error-Message                 | 0   | 0-1 | 0   | 0-1 |
   Error-Reporting-Host          | 0   | 0-1 | 0   | 0-1 |
   MIP-Candidate-Home-Agent-Host | 0-1 | 0   | 0   | 0   |
   MIP-Originating-Foreign-AAA   | 0-1 | 0   | 0-1 | 0   |
   MIP-FA-Challenge              | 0-1 | 0   | 0   | 0   |
   MIP-FA-to-HA-Key              | 0   | 0-1 | 0-1 | 0   |
   MIP-FA-to-HA-SPI              | 0   | 0   | 0   | 0-1 |
   MIP-FA-to-MN-Key              | 0   | 0-1 | 0   | 0   |
   MIP-FA-to-MN-SPI              | 0   | 0   | 0   | 0-1 |
   MIP-Feature-Vector            | 0-1 | 0-1 | 1   | 0   |
   MIP-Filter-Rule               | 0   | 0+  | 0+  | 0   |
   MIP-Foreign-Agent-Host        | 0   | 0   | 1   | 1   |
   MIP-HA-to-FA-Key              | 0   | 0-1 | 0-1 | 0   |
   MIP-HA-to-MN-Key              | 0   | 0-1 | 0-1 | 0   |
   MIP-Home-Agent-Address        | 0-1 | 0-1 | 0-1 | 0-1 |
   MIP-Key-Lifetime              | 0   | 0-1 | 0-1 | 0   |
   MIP-MN-AAA-Auth               | 1   | 0   | 0   | 0   |
   MIP-MN-to-FA-Key              | 0   | 0-1 | 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-Reg-Reply                 | 0   | 0-1 | 0   | 0-1 |
   MIP-Reg-Request               | 1   | 0   | 1   | 0   |
   Origin-Host                   | 1   | 1   | 1   | 1   |
   Origin-Realm                  | 1   | 1   | 1   | 1   |
   Original-State-Id             | 0-1 | 0-1 | 0-1 | 0-1 |
   Proxy-Info                    | 0+  | 0+  | 0+  | 0+  |
   Redirect-Host                 | 0   | 0+  | 0   | 0+  |
   Redirect-Host-Usage           | 0   | 0-1 | 0   | 0-1 |
   Redirect-Max-Cache-Time       | 0   | 0-1 | 0   | 0-1 |
   Result-Code                   | 0   | 1   | 0   | 1   |
   Re-Auth-Request-Type          | 0   | 0-1 | 0   | 0   |
   Route-Record                  | 0+  | 0   | 0+  | 0   |
   Session-Id                    | 1   | 1   | 1   | 1   |
   Session-Timeout               | 0   | 1   | 1   | 0   |
   User-Name                     | 1   | 0-1 | 1   | 0-1 |
   ------------------------------|-----+-----+-----+-----|



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8.2  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
   in [DIAMBASE].

                                        +-------------+
                                        | Command-Code|
                                        |------+------+
   Attribute Name                       |  ACR |  ACA |
   -------------------------------------|------+------+
   Accounting-Input-Octets              |  1   |  0-1 |
   Accounting-Input-Packets             |  1   |  0-1 |
   Accounting-Output-Octets             |  1   |  0-1 |
   Accounting-Output-Packets            |  1   |  0-1 |
   Accounting-Multi-Session-Id          |  1   |  0-1 |
   Acct-Session-Time                    |  1   |  0-1 |
   MIP-Feature-Vector                   |  1   |  0-1 |
   MIP-Home-Agent-Address               |  1   |  0-1 |
   MIP-Mobile-Node-Address              |  1   |  0-1 |
   -------------------------------------|------+------+


9.0  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.


9.1  Command Codes

   This specification assigns the values 260 and 262 from the Command
   Code namespace defined in [DIAMBASE]. See section 2.0 for the
   assignment of the namespace in this specification.


9.2  AVP Codes

   This specification assigns the values 318-347 and 363-367 from the
   AVP Code namespace defined in [DIAMBASE]. See sections 4.0 and 6.0
   for the assignment of the namespace in this specification.








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9.3  Result-Code AVP Values

   This specification assigns the values 4005-4007, and 5024 from the
   Result-Code AVP (AVP Code 268) value namespace defined in [DIAMBASE].
   See section 3.0 for the assignment of the namespace in this
   specification.


9.4  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 4.5. The remaining bits should only be assigned via
   Standards Action [IANA].


9.5  MIP-Algorithm-Type AVP Values

   As defined in Section 6.8, the MIP-Algorithm-Type AVP (AVP Code 345)
   defines the values 1-3. All remaining values are available for
   assignment via Designated Expert [IANA].


9.6  MIP-Replay-Mode AVP Values

   As defined in Section 6.9, the MIP-Replay-Mode AVP (AVP Code 346)
   defines the values 1-3. All remaining values, except zero, are
   available for assignment via Designated Expert [IANA].


9.7  Application Identifier

   This specification assigns the value four (4) to the Application
   Identifier namespace defined in [DIAMBASE]. See section 1.7 for more
   information.


10.0  Security Considerations

   This specification describes the Diameter Application 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 [MIPCHAL]. This
   specification also defines a method by which the home Diameter server
   can create and distribute session keys to be used to authenticate
   Mobile IP registration messages. The keys SHOULD be be protected
   using the methods defined in [CMS].




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11.0 References

11.1 Normative

[DIAMBASE]     P. Calhoun, H. Akhtar, J. Arkko, E. Guttman, A. Rubens,
               "Diameter Base Protocol", draft-ietf-aaa-diameter-08.txt,
               IETF work in progress, November 2001.

[IANA]         Narten, Alvestrand,"Guidelines for Writing an IANA Con¡
               siderations Section in RFCs", BCP 26, RFC 2434, October
               1998

[MOBILEIP]     C. Perkins, Editor. IP Mobility Support. RFC 2002, Octo¡
               ber 1996.

[MIPCHAL]      C. Perkins, P. Calhoun, "Mobile IP Challenge/Response
               Extensions". RFC 3012. November 2000.

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

[CMS]          P. Calhoun, W. Bulley, S. Farrell, "Diameter CMS Security
               Application", draft-ietf-aaa-diameter-cms-sec-03.txt,
               IETF work in progress, November 2001.

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

[MIPKEYS]      C. Perkins, P. Calhoun, "AAA Registration Keys for Mobile
               IP", draft-ietf-mobileip-aaa-key-08.txt, IETF work in
               progress, July 2001.


11.2 Informative

[MIPREQ]       S. Glass, S. Jacobs, C. Perkins, "Mobile IP Authentica¡
               tion, Authorization, and Accounting Requirements". RFC
               2977. October 2000.

[CDMA2000]     T. Hiller and al, "CDMA2000 Wireless Data Requirements
               for AAA", RFC 3141, June 2001.

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

[EVALROAM]     B. Aboba, G. Zorn, "Criteria for Evaluating Roaming Pro¡
               tocols", RFC 2477, January 1999.



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[MIPNAI]       P. Calhoun, C. Perkins, "Mobile IP Network Address Iden¡
               tifier Extension", RFC 2794, March 2000.

[RANDOM]       D. Eastlake, 3rd, S. Crocker, and J. Schiller.  Random¡
               ness Recommendations for Security.  Request for Comments
               (Informational) 1750, Internet Engineering Task Force,
               December 1994.


12.0  Acknowledgements

   The authors would like to thank Nenad Trifunovic, Haseeb Akhtar and
   Pankaj Patel for their participation in the pre-IETF Document Reading
   Party, to Erik Guttman for his very useful proposed text, and to
   Fredrik Johansson, Martin Julien and Bob Kopacz for their very useful
   contributed text.

   The authors would also like to thank the participants of 3GPP2's TSG-
   P working group for their valuable feedback and also the following
   people for their contribution in the development of the protocol:

   Kevin Purser, Thomas Panagiotis, Mark Eklund, Paul Funk, Michael
   Chen, Henry Haverinen

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


13.0  Authors' Addresses

   Questions about this memo can be directed to:

      Pat R. Calhoun
      Black Storm Networks
      250 Cambridge Avenue, Suite 200
      Palo Alto, California, 94306
      USA

       Phone:  +1 650-617-2932
         Fax:  +1 650-786-6445
      E-mail:  pcalhoun@bstormnetworks.com










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      Tony Johansson
      Ericsson Inc
      2100 Shattuck Avenue
      Berkeley, California 94704
      USA

      Phone:  +1 510-541-8783
        Fax:  +1 510-666-3900
      E-Mail: tony.johansson@ericsson.com

      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


14.0  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.






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15.0  Expiration Date

   This memo is filed as <draft-ietf-aaa-diameter-mobileip-09.txt> and
   expires in September 2002.















































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