AAA Working Group Pat R. Calhoun Internet-Draft Black Storm Networks Category: Standards Track Charles E. Perkins <draft-ietf-aaa-diameter-mobileip-08.txt> Nokia Research Center November 2001 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 RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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/ietf/1id-abstracts.txt 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 2001. All Rights Reserved. Calhoun, Perkins expires May 2002 [Page 1]
Internet-Draft November 2001 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. 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 5.0 Key Distribution Center 5.1 Key Material vs. Session Key Calhoun, Perkins expires May 2002 [Page 2]
Internet-Draft November 2001 5.2 Distributing the Mobile-Home Session Key 5.3 Distributing the Mobile-Foreign Session Key 5.4 Distributing the Foreign-Home Session Key 5.5 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 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-Extended-Octets AVP 7.2 Accounting-Output-Extended-Octets AVP 7.3 Accounting-Session-Time AVP 7.4 Accounting-Input-Extended-Packets AVP 7.5 Accounting-Output-Extended-Packets AVP 8.0 AVP Table 8.1 Mobile IP Command AVP Table 8.2 Accounting AVP Table 9.0 Acknowledgements 10.0 IANA Considerations 10.1 Command Codes 10.2 AVP Codes 10.3 Result-Code AVP Values 10.4 MIP-Feature-Vector AVP Values 10.5 MIP-Algorithm-Type AVP Values 10.6 MIP-Replay-Mode AVP Values 10.7 Application Identifier 11.0 Security Considerations 12.0 Acknowledgements 13.0 References 14.0 Authors' Addresses 15.0 Full Copyright Statement 16.0 Expiration Date 1.0 Introduction Mobile IP, as defined in [4], defines a method that allows a Mobile Node to change its point of attachment to the Internet with minimal Calhoun, Perkins expires May 2002 [Page 3]
Internet-Draft November 2001 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 [4] 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 [4] to work just as well when mobile nodes do not have a static home agent and home address. Recent specification [8] allows a mobile node to use its NAI instead of its home address, which better accommodates current administrative practice. This document specifies Application 4 to the Diameter base protocol [1] that allows a Diameter server to authenticate, authorize and collect accounting information for Mobile IPv4 services rendered to a mobile node. This 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 [4] specifies a security model that requires that mobile nodes and home agents share a pre-existing security association, which leads to scaling and configuration issues. This specification defines Diameter functions that allow the AAA server to act as a Key Distribution Center (KDC), whereby dynamic 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 [6], which is used for Diameter message routing purposes. Mobile nodes include their NAI in Registration messages, as defined in [8]. The use of the NAI is consistent with the roaming model defined by the ROAMOPS Working Group [7]. 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. AAAH, AAAF, proxies and relays agents MUST maintain transaction state. Given the nature of Mobile IP, a re-authentication can only be Calhoun, Perkins expires May 2002 [Page 4]
Internet-Draft November 2001 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 [3, 16]. Later subsections in this introductory section provide some examples and message flows of the Mobile IP and Diameter messages that occur when a Mobile Node requests service in a foreign network. In this document, the role of the "attendant" [3] is performed by 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 [11]. 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. Calhoun, Perkins expires May 2002 [Page 5]
Internet-Draft November 2001 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 [1] to determine whether the AMR should be processed locally, or if it should be forwarded to another Diameter Server, known as the AAA- Home, or AAAH. Figure 1 shows an example in which a mobile node (mn@xyz.com) requests service from a foreign provider (abc.com). The request received by the AAAF is forwarded to xyz.com's AAAH server. Figure 2 shows the message flows involved when the 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 (and session keys, if allocated by the AAA server) is communicated through the Authorization-Lifetime AVP in the AA-Mobile- Node-Answer (AMA, see section 2.2) from the AAAH. Calhoun, Perkins expires May 2002 [Page 6]
Internet-Draft November 2001 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 [5]. The mobile node includes the Challenge and MN-AAA authentication extension to enable authorization by AAAH. If the authentication data supplied in the MN-AAA extension is invalid, AAAH returns the response (AMA) with the Result-Code AVP set to DIAMETER_AUTHENTICATION_REJECTED. 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- Calhoun, Perkins expires May 2002 [Page 7]
Internet-Draft November 2001 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. For new sessions, the AAAH MUST create an accounting session identifier, which is added to the Accounting-Multi-Session-Id AVP in the HAR message sent to the home agent. 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). Of course, an AAAH MUST use the same session identifier for all HARs initiated on behalf of a given mobile node's session. A mobile node's session is identified via its identity in the User-Name AVP, the MIP- Mobile-Node-Address and MIP-Home-Agent-Address AVPs. This is necessary in order to allow the session state machine, defined in the base protocol [1], 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). Calhoun, Perkins expires May 2002 [Page 8]
Internet-Draft November 2001 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 Accounting-Multi-Session-Id AVP in the HAR MUST be included in the HAA, which is then forwarded 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. 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 quite likely 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, it is necessary for Calhoun, Perkins expires May 2002 [Page 9]
Internet-Draft November 2001 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 new AAAH and session identifier. 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, in the event that a home agent receives an HAR with a different Accounting- Multi-Session-id AVP (and obviously a different Session-Id AVP), the home agent MUST send an HAA with the Accounting-Multi-Session-Id AVP that was received by the AAAH in the first HAR for the mobile's session. This modified 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 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 [3, 16]. When a foreign agent detects that the mobile node has a home agent address equal to 0.0.0.0 or 255.255.255.255 in the Registration Request message, it MUST add a MIP-Feature-Vector AVP with the Home-Agent- Requested flag set to one. If the home agent address is equal to 255.255.255.255, then the foreign agent also MUST set the Home- Address-Allocatable-Only-in-Home-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 a AMR message with the Home-Agent-Requested flag set to one, and the Home-Address-Allocatable-Only-in-Home-Realm flag equal to zero, AAAF MAY set the Foreign-Home-Agent-Available Calhoun, Perkins expires May 2002 [Page 10]
Internet-Draft November 2001 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, containing the identity of the home agent that would be assigned to the mobile node. 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 a AMR message, it first checks the authentication data supplied by the mobile node, according to the MIP-Reg-Request AVP and MIP-MN-AAA-Auth AVP, and determines whether to authorize the mobile node. If the AMR indicates that the AAAF has offered to allocate a home agent for the mobile node, then the AAAH must decide whether its local policy would allow the user to have a Home Agent in the foreign network. If so, and after checking authorization from the data in the AMR message, the AAAH sends the HAR message to the AAAF that does not contain the MIP-Home-Agent- Address, but includes the Destination-Host AVP set to the value of the AMR's MIP-Candidate-Home-Agent-Host AVP. 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. Calhoun, Perkins expires May 2002 [Page 11]
Internet-Draft November 2001 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, with the Result-Code AVP indicating success, 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. The HAA and AMA MUST include the MIP-Home-Agent-Address and the MIP-Mobile-Node-Address AVPs. 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 Calhoun, Perkins expires May 2002 [Page 12]
Internet-Draft November 2001 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. +---------------+ +---------------+ +-------------+ |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 successful HAA, the AAAF will forward the HAA back to the AAAH. The HAA MUST include the MIP-Home-Agent-Address and the MIP-Mobile-Node-Address AVPs. The AAAH will then send back an AMA to the AAAF in foreign network 2. If the old Foreign Network does not permit the use of its Home Agent Calhoun, Perkins expires May 2002 [Page 13]
Internet-Draft November 2001 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 AAAF overseeing the Home Agent to enable it to release any resources. 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. 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- Calhoun, Perkins expires May 2002 [Page 14]
Internet-Draft November 2001 Request (STR) [1] to their respective Diameter servers. The Home Diameter server SHOULD only deallocate all resources after the STR is received from the Home Agent. This ensures that a Mobile Node that moves from one Foreign Agent to another (hand-off) does not cause the Home Diameter Server to free all resources for the Mobile Node. In the event that the AAAF wishes to terminate a session, its Abort- Session-Request (ASR) [1] 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 [1]. 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 [1] values that MUST be supported by all Diameter implementations conforming to this specification. The following Command Codes are defined in this specification: Calhoun, Perkins expires May 2002 [Page 15]
Internet-Draft November 2001 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 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 [1]). 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. Calhoun, Perkins expires May 2002 [Page 16]
Internet-Draft November 2001 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 ] [ 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 Result-Code AVP MAY contain one of the values defined in section 3.0, in addition to the values defined in [1]. An AMA message with the Result-Code AVP set to DIAMETER_SUCCESS MUST include the MIP-Home-Agent-Address, MIP-Home-Mobile-Node-Address and MIP-Reg-Reply AVPs. 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. 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 Calhoun, Perkins expires May 2002 [Page 17]
Internet-Draft November 2001 node. Upon receipt of this result code, the foreign agent MUST issue the Registration Request to the Home Agent in the manner described in [4]. 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. Message Format <AA-Mobile-Node-Answer> ::= < Diameter Header: 260, PXY > < Session-Id > { Auth-Application-Id } { Result-Code } { Origin-Host } { Origin-Realm } [ Accounting-Multi-Session-Id ] [ Authorization-Lifetime ] [ Auth-Grace-Period ] [ Auth-Session-State ] [ Error-Message ] [ Error-Reporting-Host ] [ Re-Auth-Request-Type ] [ 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 Calhoun, Perkins expires May 2002 [Page 18]
Internet-Draft November 2001 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 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 } { Accounting-Multi-Session-Id } { 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-Mobile-Node-Address ] [ MIP-Home-Agent-Address ] * [ MIP-Filter-Rule ] [ Session-Timeout ] [ Origin-State-Id ] * [ AVP ] * [ Proxy-Info ] * [ Route-Record ] Calhoun, Perkins expires May 2002 [Page 19]
Internet-Draft November 2001 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. If the home agent allocated a home address for the Mobile Node, the address MUST be included in the MIP-Mobile-Node- Address AVP. The Result-Code AVP MAY contain one of the values defined in section 3.0 instead of the values defined in [1]. 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 ] [ 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 [1] values that MUST be supported by all Diameter implementations that conform to this specification. 3.1 Transient Failures Errors that fall within the transient failures category are used to inform a peer that the request could not be satisfied at the time it was received, but MAY be able to satisfy the request in the future. DIAMETER_ERROR_MIP_REPLY_FAILURE 4005 This error code is used by the Home Agent when processing of the Registration Request has failed. Calhoun, Perkins expires May 2002 [Page 20]
Internet-Draft November 2001 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. 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. Calhoun, Perkins expires May 2002 [Page 21]
Internet-Draft November 2001 +---------------------+ | 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 | 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 [4] 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 [4] 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. Calhoun, Perkins expires May 2002 [Page 22]
Internet-Draft November 2001 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. 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 Calhoun, Perkins expires May 2002 [Page 23]
Internet-Draft November 2001 MN-HA-Key-Request flag to one. The MN-HA-Key-Request flag is also set to one if the mobile node includes a Generalized MN-HA Key Request [15] extension, with the subtype set to AAA. If the mobile node includes a Generalized MN-FA Key Request [15] extension with the AAA subtype in its Registration Request, the Foreign Agent sets the MN-FA-Key-Request flag to one in the MIP- Feature-Vector AVP. If the mobile node requests a home agent in the foreign network 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. 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 [4] 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 } Calhoun, Perkins expires May 2002 [Page 24]
Internet-Draft November 2001 { 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). 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 Calhoun, Perkins expires May 2002 [Page 25]
Internet-Draft November 2001 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-Home-Agent-Host The MIP-Home-Agent-Host AVP (AVP Code TBD) is of type DiameterIdentity and contains the identity of the home agent requested by the mobile node in its registration request. This AVP is used by the AAAH to determine the destination of the HAR. 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 [4]: 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 [9]. The MIP-Key-Lifetime AVP contains the number of seconds before session keys destined for the Home Agent and/or Foreign Agent expire. A value of zero indicates infinity (no timeout). 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. Calhoun, Perkins expires May 2002 [Page 26]
Internet-Draft November 2001 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 [15], 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 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 [18] 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 [15]. 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 [18] 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 is the same as the one used by the AAAH in the session key generation procedure. Therefore, the AAAH MUST know a priori the transform used, which is typically contained in the mobile node's configuration profile. The session keys destined for mobility agents are encoded using the security association available between the AAA server and the agents (e.g. IPSec, TLS, CMS). Calhoun, Perkins expires May 2002 [Page 27]
Internet-Draft November 2001 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 [18] 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. 5.2 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 does not transmit the HAR to the home agent, but instead transmits the HAR to the AAAF. When the AAAF receives the HAR, it first allocates a home agent, and then issues the HAR for that home agent. The AAAH also has to arrange for the key to be delivered to the mobile node. Unfortunately, the AAA server only knows about Diameter messages and AVPs, and the mobile node only knows about Mobile IP messages and extensions [4]. For this purpose, AAAH encodes the Mobile-Home 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 [15] 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 Calhoun, Perkins expires May 2002 [Page 28]
Internet-Draft November 2001 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 [15], 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-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. 5.3 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 [15] 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. 5.4 Distributing the Foreign-Home Session Key If the home agent is in the home realm, then AAAH has to generate the Foreign-Home session key. Otherwise, it is generated by AAAF. Calhoun, Perkins expires May 2002 [Page 29]
Internet-Draft November 2001 In either case, 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 that is to be sent to the foreign agent is cached on the AAAH until the HAA is received. 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 Diameter server responsible for key allocation 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 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 Calhoun, Perkins expires May 2002 [Page 30]
Internet-Draft November 2001 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 [9] 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. +---------------------+ | 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 ] Calhoun, Perkins expires May 2002 [Page 31]
Internet-Draft November 2001 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 ] 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 [15]. 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. Calhoun, Perkins expires May 2002 [Page 32]
Internet-Draft November 2001 MIP-MN-to-FA-Key ::= < AVP Header: 325 > { MIP-Algorithm-Type } { MIP-Key-Material } { MIP-MN-AAA-SPI } * [ AVP ] 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 [15]. 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 ] 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 [4] 2 HMAC-MD5 [13] 3 SHA-1 [17] 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 Calhoun, Perkins expires May 2002 [Page 33]
Internet-Draft November 2001 authenticating the Mobile Node. The following values are supported (see [4] 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 [4]. 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 [4]. This AVP MAY be added in the HAA message by the Home Agent for the AAAH's use in MIP-FA-to-HA-SPI AVP of the 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 [15] to generate the session key used to authenticate Mobile IP registration messages. 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. Calhoun, Perkins expires May 2002 [Page 34]
Internet-Draft November 2001 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-Extended-Octets AVP The Accounting-Input-Extended-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-Extended-Octets AVP The Accounting-Output-Extended-Octets AVP (AVP Code 364) is of type Unsigned64, and contains the number of octets in IP packets sent to the user. 7.3 Accounting-Session-Time AVP The Accounting-Session-Time AVP (AVP Code 46) is of type Unsigned32, and indicates the length of the current session in seconds. 7.4 Accounting-Input-Extended-Packets AVP The Accounting-Input-Extended-Packets (AVP Code 365) is of type Unsigned64, and contains the number of IP packets received from the user. 7.5 Accounting-Output-Extended-Packets AVP The Accounting-Output-Extended-Packets (AVP Code 366) is of type Unsigned64, and contains the number of IP packets sent to the user. 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. Calhoun, Perkins expires May 2002 [Page 35]
Internet-Draft November 2001 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. Calhoun, Perkins expires May 2002 [Page 36]
Internet-Draft November 2001 +-----------------------+ | 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 | 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-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 | 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 | 0 | ------------------------------|-----+-----+-----+-----| Calhoun, Perkins expires May 2002 [Page 37]
Internet-Draft November 2001 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 [1]. +-------------+ | Command-Code| |------+------+ Attribute Name | ACR | ACA | -------------------------------------|------+------+ Accounting-Input-Extended-Octets | 1 | 0-1 | Accounting-Input-Extended-Packets | 1 | 0-1 | Accounting-Output-Extended-Octets | 1 | 0-1 | Accounting-Output-Extended-Packets | 1 | 0-1 | Accounting-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 Acknowledgements The following people have contributed text to this document: Fredrik Johansson, Martin Julien The authors would like to thank Nenad Trifunovic, Haseeb Akhtar and Pankaj Patel for their participation in the Document Reading Party, to Erik Guttman for his very useful proposed text, and to Tony Johansson for the proposed text AND being in the doc reading party. The authors would also like to thank the participants of 3GPP2's TSG- P working group for their valuable feedback. 10.0 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. 10.1 Command Codes This specification assigns the values 260 and 262 from the Command Code namespace defined in [1]. See section 2.0 for the assignment of the namespace in this specification. Calhoun, Perkins expires May 2002 [Page 38]
Internet-Draft November 2001 10.2 AVP Codes This specification assigns the values 318-346 and 363-367 from the AVP Code namespace defined in [1]. See sections 4.0 and 6.0 for the assignment of the namespace in this specification. 10.3 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 [1]. See section 3.0 for the assignment of the namespace in this specification. 10.4 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 [2]. 10.5 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 [2]. 10.6 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 [2]. 10.7 Application Identifier This specification assigns the value four (4) to the Application Identifier namespace defined in [1]. See section 1.7 for more information. 11.0 Security Considerations This specification describes the Diameter Application necessary to authenticate and authorize a Mobile IP Mobile Node. The Calhoun, Perkins expires May 2002 [Page 39]
Internet-Draft November 2001 authentication algorithm used is dependent upon the transforms available by the Mobile IP protocol, and [5]. This specification also defines a method by which the home Diameter server can create and distribute session keys to be used to authenticate Mobile IP registration messages. The keys SHOULD be be protected using the methods defined in [9]. 12.0 Acknowledgements 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 References [1] 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. [2] Narten, Alvestrand,"Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998 [3] S. Glass, S. Jacobs, C. Perkins, "Mobile IP Authentication, Autho- rization, and Accounting Requirements". RFC 2977. October 2000. [4] C. Perkins, Editor. IP Mobility Support. RFC 2002, October 1996. [5] C. Perkins, P. Calhoun, "Mobile IP Challenge/Response Extensions". RFC 3012. November 2000. [6] B. Aboba, M. Beadles "The Network Access Identifier." RFC 2486. January 1999. [7] B. Aboba, G. Zorn, "Criteria for Evaluating Roaming Protocols", RFC 2477, January 1999. [8] P. Calhoun, C. Perkins, "Mobile IP Network Address Identifier Extension", RFC 2794, March 2000. [9] P. Calhoun, W. Bulley, S. Farrell, "Diameter CMS Security Applica- tion", draft-ietf-aaa-diameter-cms-sec-03.txt, IETF work in progress, November 2001. [10] Kent, Atkinson, "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998. Calhoun, Perkins expires May 2002 [Page 40]
Internet-Draft November 2001 [11] S. Bradner, "Key words for use in RFCs to Indicate Requirement Lev- els", BCP 14, RFC 2119, March 1997. [12] F. Yergeau, "UTF-8, a transformation format of ISO 10646", RFC 2279, January 1998. [13] H. Krawczyk, M. Bellare, and R. Cannetti. HMAC: Keyed-Hashing for Message Authentication. RFC 2104, February 1997. [14] P. Calhoun, W. Bulley, A. Rubens, J. Haag, "Diameter NASREQ Appli- cation", draft-ietf-aaa-diameter-nasreq-08.txt, IETF work in progress, November 2001. [15] C. Perkins, P. Calhoun, "AAA Registration Keys for Mobile IP", draft-ietf-mobileip-aaa-key-08.txt, IETF work in progress, July 2001. [16] T. Hiller and al, "CDMA2000 Wireless Data Requirements for AAA", RFC 3141, June 2001. [17] National Institute of Standards and Technology, "Secure Hash Stan- dard", Technical Report NIST FIPS PUB 180-1, U.S. Department of Commerce, April 1995. [18] D. Eastlake, 3rd, S. Crocker, and J. Schiller. Randomness Recom- mendations for Security. Request for Comments (Informational) 1750, Internet Engineering Task Force, December 1994. 14.0 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@diameter.org Calhoun, Perkins expires May 2002 [Page 41]
Internet-Draft November 2001 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 15.0 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. 16.0 Expiration Date This memo is filed as <draft-ietf-aaa-diameter-mobileip-08.txt> and expires in May 2002. Calhoun, Perkins expires May 2002 [Page 42]
