One document matched: draft-ietf-aaa-diameter-mobileip-15.txt
Differences from draft-ietf-aaa-diameter-mobileip-14.txt
AAA Working Group Pat R. Calhoun
Internet Draft Airespace
draft-ietf-aaa-diameter-mobileip-15.txt Tony Johansson
Category: Standards Track Bytemobile Inc
Charles E. Perkins
Nokia Research Center
Tom Hiller
(editor)
Lucent Technologies
November 2003
Diameter Mobile IP Application
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [1].
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.
1. Abstract
This document specifies a Diameter application that allows a Diameter
server to authenticate, authorize and collect accounting information
for Mobile IP 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.
2. Conventions used in this document
<Add any conventions that you use in your document here. Common
conventions are listed below.>
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
Calhoun et al Standards Track - March 2004 1
Diameter MIP November 2003
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119 [2].
3. 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. In addition,
another 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-ID 4 to the Diameter base
protocol [DIAMBASE] that allows a Diameter server to authenticate,
authorize and collect accounting information for Mobile IP 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 Diameter 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. Strong
authentication and confidentiality of session keys is required, and
is to be provided via mutually authenticated TLS or IPsec.
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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Diameter MIP November 2003
A home AAA server (AAAH) and foreign AAA server (AAAF), which support
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 Diameter server initiated re-
auth does not apply to this application.
Furthermore, the nature of Mobile IP also means that the mobile node
will do handoffs between different foreign agents. To guarantee that
a registered user always ends up in the same initial AAAH, the mobile
node SHOULD always include the AAAH NAI [AAANAI]. Finally, to assist
the AAAH in routing the messages to a mobile node's home agent the
mobile node SHOULD always include the HA NAI [AAANAI]. If the mobile
node does not support the Mobile IP AAA NAI extension [AAANAI], this
MAY limit the functionality that can be offered to such a mobile
node.
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.
3.2 Inter-Realm Mobile IP
When a mobile 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
+--------+ +--------+
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Diameter MIP November 2003
|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.
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
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----------- ------------- ------------ ---------- -------
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.
The above scenario causes the MN-FA and MN-HA keys to be exposed to
Diameter agents all along the Diameter route. A more proper approach
is to eliminate the AAAF and other Diameter agents as follows:
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Diameter MIP November 2003
Local redirect Home
FA AAAF Agent Server
AMR
---------------->
AMA (Redirect)
---------------->
AMA (Redirect)
<----------------
AMA (Redirect)
<----------------
Setup Security Association
<-------------------------------------------------->
AMR
-------------------------------------------------->
AMA (MN-FA key)
<---------------------------------------------------
Figure 3: Use of a Redirect Server with AMR/AMA
Figure 4 shows the HA and the AAAH are in the same network so it is
likely that the HAAA knows the IP address of the HA, and the redirect
server would therefore not be needed, but are shown for completeness.
The FA still provides the challenge and the mobile sends the RRQ,
etc., as in the previous figure, however these were eliminated from
Figure 3 and 4 to reduce figure clutter. The redirect server
eliminates the AAAF and any other Diameter agents from seeing the
keys as they are transported to the FA and HA.
Local Redirect Home
HA Agent Server
HAR
<--------------------
HAA (Redirect)
-------------------->
Setup Security Association
<---------------------------------------->
HAR (MN-HA key)
<-----------------------------------------
HAA
----------------------------------------->
Figure 4: Use of a Redirect Server with HAR/HAA
Accounting messages are sent via Diameter agents, not the direct
connection, unless network policies dictate otherwise.
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A mobile node with AAA NAI extension support [AAANAI], which has been
previously authenticated and authorized, MUST always include the
assigned home agent in the HA Identity subtype of the AAA NAI
extension, and the authorizing Home AAA server in the AAAH Identity
subtype of the AAA NAI extension, when re-authenticating. So, in the
event that the AMR generated by the FA is for a session that was
previously authorized, it MUST include the Destination-Host AVP, with
the identity of the AAAH found in the AAAH-NAI, and the MIP-Home-
Agent-Host AVP with the identity and realm of the assigned HA found
in the HA-NAI. If on the other hand the mobile node does not support
the AAA NAI extension, the FA may not have the identity of the AAAH
and the identity and realm of the assigned HA. This means that
without support of the AAA NAI extension, the FA may not be able to
guarantee, that the AMR will be destined to the same AAAH, which
previously authenticated and authorized the mobile node, since the FA
may not know the identity of the AAAH.
If the mobile node was successfully authenticated, the AAAH checks if
the home agent was located in the foreign realm, by checking Home-
Agent-In-Foreign-Network flag of the MIP-Feature-Vector AVP. Other
AVP's like the MIP-Home-Agent-Host AVP and the MIP-Originating-
Foreign-AAA AVP may also be used to verify the location of the home
agent. If the home agent is located in the home realm, then the AAAH
sends an HAR message to the home agent, which contains a MIP-Reg-
Request AVP.
However, as in the case of the AMA and the MN-FA key, using Diameter
agents exposes the MN-HA key to Diameter agents along the way.
Figure 4 shows the use of a redirect server to avoid this problem.
If the home agent was not located in the foreign realm, the AAAH
checks for the MIP-Home-Agent-Address AVP and if present the MIP-
Home-Agent-Host AVP. If one was specified, the AAAH checks that the
address is that of a known home agent and that the mobile node is
allowed to request this particular home agent, and that the home
agent's identity is included in the MIP-Home-Agent-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. Refer
to Figure 4 if the HA does not have a direct path to the HA. 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.
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Diameter MIP November 2003
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 MUST 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.
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 5).
STR, Session-Id = foo STR, Session-Id = bar
---------------------> <--------------------
+----+ +------+ +------+ +----+
| FA | | AAAF | | AAAH | | HA |
+----+ +------+ +------+ +----+
<--------------------- --------------------->
STA, Session-Id = foo STA, Session-Id = bar
Figure 5: 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. In the creation of the Registration Reply the Home Agent must
include the HA NAI and the AAAH NAI, which will be created from the
Origin-Host AVP and Origin-Realm AVP of the HAR. If a home address is
needed, the home agent MUST also assign one and include the address
in both the Registration Reply and within the MIP-Mobile-Node-Address
AVP.
The HA MUST include an Acct-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 Acct-Multi-Session-Id
that was present in the HAA, and the MIP-Home-Agent-Address, MIP-
Mobile-Node-Address AVPs in the AMA message. See Figure 3 and 4 for
the use of the redirect agent for the secure transport of the HAA and
AMA messages.
3.3 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
Calhoun Standards Track - March 2003 8
Diameter MIP November 2003
a foreign agent is not aware that a registration request from a
mobile node has been previously authorized.
A handoff registration request from a mobile node will cause an AMR
to be sent to its AAAF. The AMR will include a new session
identifier, and MAY be sent to an AAAF in the visited network other
than the AAAF, which received the previous AMR. However, with the
usage of the AAA NAI, this AMR is guaranteed to be received by the
AAAH to which the user is currently registered.
As discussed above, it may be undesirable for keys, such as the MN-FA
keys, to be exposed to any Diameter Agents. In this case the FA
should establish a security association with the AAAH directly, using
redirects as described above. This completely eliminates the AAAF
from the transaction.
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 new 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 Acct-Multi-Session-Id AVP value in all
HAAs for the mobile's session. That is, the HA generates a unique
Acct-Multi-Session-Id when receiving an HAR for a new session, and
returns this same value in every HAA for the session. This Acct-
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
Acct-Multi-Session-Id in the accounting messages.
ACR, Session-Id = foo ACR, Session-Id = bar
Acct-Multi-Session-Id = a Acct-Multi-Session-Id = a
---------------------> <--------------------
+----+ +------+ +------+ +----+
| FA | | AAAF | | AAAH | | HA |
+----+ +------+ +------+ +----+
<--------------------- --------------------->
ACA, Session-Id = foo ACA, Session-Id = bar
Figure 6: Accounting messages w/ Mobile IP Application
3.4 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-
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Diameter MIP November 2003
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 with AAA NAI extension support
[AAANAI] has been previously authorized by the AAAH and now needs to
be re-authenticated, and requests to keep the assigned home agent in
the foreign network, the mobile node MUST include the HA NAI and the
AAAH NAI in the registration request to the FA. Upon receipt, the FA
will create the AMR including the MIP-Home-Agent-Address AVP, the
Destination-Host AVP based on the AAAH NAI and include the MIP-Home-
Agent-Host AVP based on the home agent NAI. If the AAAF authorizes
the use of the requested home agent, the AAAF MUST set the Home-
Agent-In-Foreign-Network bit in the MIP-Feature-Vector AVP.
In the event that the mobile node that does not support the AAA NAI
extension has been previously authorized by the AAAH and now needs to
be re-authenticated, and requests to keep the assigned home agent in
the foreign network, the mobile node sends a registration request
without the AAA NAI and the HA NAI. Upon receipt, the FA will create
the AMR including the MIP-Home-Agent-Address AVP. If the AAAF
authorizes the use of the requested home agent, and if it has
knowledge that the requested home agent is in its own domain, the
AAAF MUST set the Home-Agent-In-Foreign-Network bit in the MIP-
Feature-Vector AVP.
As above, the use of Diameter servers in this exchange will expose
keys. If this is deemed undesirable, a redirect server approach
should be utilized to communicate the AMR to the AAAH. This causes
the FA to communicate the AMR directly to the AAAH via a security
association.
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, i.e. the
Foreign-Home-Agent-Available is set in the MIP-Feature-Vector AVP, or
the AMR indicates that the AAAF has offered a previously allocated
Home Agent for the mobile node, i.e. the Home-Agent-In-Foreign-
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Diameter MIP November 2003
Network is set in the MIP-Feature-Vector AVP, then the AAAH must
decide whether its local policy would allow the user to have a Home
Agent in the foreign network or to keep the 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 by
including the Destination-Host AVP set to the value found in the
AMR's MIP-Candidate-Home-Agent-Host AVP or MIP-Home-Agent-Host AVP if
the HA has been previously allocated and authorized by the AAAH. If
the HA has not been previously allocated by the foreign domain, the
HAR sent by the AAAH does not contain the MIP-Home-Agent-Address.
If the AAAH does not have the IP address of the HA and if there isn't
a security association, then a redirect server approach of Figure Y
should be utilized to communicate the HAR to the HA. This requires a
security association between the AAAH and HA be established. If the
redirect server cannot resolve the HA, or no security association can
be established, the AAAH MUST return an AMA with the Result-Code AVP
set to DIAMETER_ERROR_END_TO_END_MIP_KEY_ENCRYPTION.
If Diameter agents are being used (i.e., there is no redirect server,
etc.) the AAAH sends the HAR to the originating AAAF. In this HAR the
Destination-Host AVP is set to the value found in the AMR's MIP-
Originating-Foreign-AAA AVP, and the MIP-Home-Agent-Host AVP or the
MIP-Candidate-Home-Agent-Host AVP found in the AMR are copied into
the HAR.
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 receives the HAR, this new AAAF will send the HAR to the HA.
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 7: Home Agent allocated in Visited Realm
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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.
Mobile Node Foreign Agent Home Agent AAAF AAAH
----------- ------------- ------------- ---------- ----------
<----Challenge----
Reg-Req (Response)->
------------AMR------------->
-----AMR---->
<----HAR-----
<-----HAR------
------HAA------>
-----HAA---->
<----AMA-----
<-------------AMA------------
<---Reg-Reply----
Figure 8: Mobile IP/Diameter Message Exchange when HA is allocated in
Visited Realm
Figures 9 and 10 shows the secure approach involving redirect agents.
Local Redirect Home
FA FAAA Agent Server
AMR
--------------->
AMR
(Redirect, f-HA)
-------------------->
AMA
(Redirect, f-HA))
<--------------------
AMA
(Redirect, f-HA)
<---------------
AMR (f-HA)
------------------------------------------------------>
AMA (MN-FA key)
<------------------------------------------------------
Figure 9: Use of Redirect Server for AMR/AMA
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Diameter MIP November 2003
Local Redirect Home
HA Agent Server
HAR
<----------------------
HAA (Redirect)
---------------------->
HAR (MN-HA key)
<------------------------------------------
HAA
------------------------------------------>
Figure 10: Use of Redirect Server for HAR/HAA
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 AAAH will have to
provide services for both visited networks, e.g., key refresh, per
Figures 9 and 10.
3.5 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 Acct-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 +---------+
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Diameter MIP November 2003
Figure 11: 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.
Figure 12 shows the secure solution using redirect servers. In
Figure 12, the Proxy AAA represents any AAA server or servers that
the HA may use. This applies to the visited or home network.
Local redirect Home
HA Proxy AAA Agent Server
AMR
--------------->
AMR (Redirect)
-------------------->
AMA (Redirect)
<---------------------
AMA (Redirect)
<----------------
Setup Security Association
<------------------------------------------------------>
AMR
------------------------------------------------------->
AMA (MN-HA key)
<-------------------------------------------------------
Figure 12: Use of Redirect Server for Co-located CoA and AMR/AMA
3.6 Key Distribution Center (KDC)
In order to allow the scaling of wireless data access across
administrative domains, it is necessary to minimize the specific
security associations required. This means that each Foreign Agent
should not be required have a pre-configured shared security
association with each Home Agent on the Internet, nor should the
mobile node be required to have a pre-configured shared security
association with any specific home agent or any specific foreign
agent, as defined in [MOBILEIP].
Diameter Mobile IP application solves this by including a key
distribution center (KDC), which means that after a Mobile Node is
authenticated, the authorization phase includes the generation of
sessions keys. Specifically, three keys are generated and are
required by [MOBILEIP]:
- K1 - the MN-HA Key, which will work as security association
between
the Mobile Node and the Home Agent.
- K2 - the MN-FA Key, which will work as the security association
Calhoun Standards Track - March 2003 14
Diameter MIP November 2003
between the Mobile Node and the Foreign Agent
- K3 - the FA-HA Key, which will work as the security association
between the Foreign Agent and the Home Agent
Figure 13 depicts the new security associations used for Mobile-IP
message integrity using the keys derived by the DIAMETER server.
+--------+ +--------+
|Foreign | K3 | Home |
|Agent |<-------------------->| Agent |
| | | |
+--------+ +--------+
^ ^
| K2 K1 |
| +--------+ |
| | Mobile | |
+------>| Node |<------+
| |
+--------+
Figure 13 - Security Association after Key Distribution
If the home agent is assigned in the home network, each key is
generated and encrypted by the home Diameter server. If instead the
home agent is assigned in the foreign network the K3 key is generated
and encrypted by the foreign network's local Diameter server, while
the K1 and K2 is still generated and encrypted by the home Diameter
server.
The keys destined for the foreign and home agent are propagated to
the mobility nodes via the Diameter protocol, and the keys must be
protected either by IPSec or TLS security associations that exist
directly between the HA and AAAH or the FA and AAAF, as explained
above.
The keys destined for the mobile node must also be propagated via the
Mobile IP protocol and must therefore instead follow the mechanisms
described in [aaa-keys]. In [MIPKEYS], the keys distributed to the
mobile node are instead sent as a nonce, and the mobile node and the
home Diameter will use the nonce and the long-term shared secret to
create the keys (see section 5.2).
Once the session keys have been established and propagated, the
mobility devices can exchange registration information directly as
defined in [MOBILEIP] without the need of the Diameter
infrastructure. However the session keys have a lifetime, after
which the Diameter infrastructure must be invoked again to acquire
new session keys.
3.7 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
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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.
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.
When deallocating all of the mobile node's resources the home
Diameter server (and the foreign Diameter server in case of HA
allocated in foreign network) MUST destroy all session keys that may
still be valid.
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.
3.8 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].
4.0 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
4.1 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:
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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)
Home Agent NAI (MIP-Home-Agent-Host AVP)
Home AAA server NAI (Destination-Host AVP [DIAMBASE])
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 home 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.
If the mobile node includes the home agent NAI and the home AAA
server NAI [AAANAI], the foreign agent MUST include the MIP-Home-
Agent-Host AVP and the Destination-Host AVP in the AMR.
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 }
[ Acct-Multi-Session-Id ]
[ Destination-Host ]
[ Origin-State-Id ]
[ MIP-Mobile-Node-Address ]
[ MIP-Home-Agent-Address ]
[ MIP-Feature-Vector ]
[ MIP-Originating-Foreign-AAA ]
[ Authorization-Lifetime ]
[ Auth-Session-State ]
[ MIP-FA-Challenge ]
[ MIP-Candidate-Home-Agent-Host ]
[ MIP-Home-Agent-Host ]
[ MIP-HA-to-FA-SPI ]
* [ Proxy-Info ]
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* [ Route-Record ]
* [ AVP ]
4.2 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-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.
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.
Message Format
<AA-Mobile-Node-Answer> ::= < Diameter Header: 260, PXY >
< Session-Id >
{ Auth-Application-Id }
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ Acct-Multi-Session-Id ]
[ User-Name ]
[ Authorization-Lifetime ]
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[ 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-Key-Lifetime ]
[ MIP-Type-Algorithm ]
[ MIP-Home-Agent-Address ]
[ MIP-Mobile-Node-Address ]
* [ MIP-Filter-Rule ]
[ Origin-State-Id ]
* [ Proxy-Info ]
* [ AVP ]
4.3 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
the mobile nodes address. If on the other hand the home agent's local
AAA server allocates the mobile node's home address, the local AAA
server 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-Session-State }
{ MIP-Reg-Request }
{ Origin-Host }
{ Origin-Realm }
{ User-Name }
{ Destination-Realm }
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{ 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-HA-to-FA-SPI ]
[ MIP-Key-Lifetime ]
[ MIP-Originating-Foreign-AAA ]
[ MIP-Mobile-Node-Address ]
[ MIP-Home-Agent-Address ]
[ MIP-Type-Algorithm ]
* [ MIP-Filter-Rule ]
[ Origin-State-Id ]
* [ Proxy-Info ]
* [ Route-Record ]
* [ AVP ]
4.4 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].
Message Format
<Home-Agent-MIP-Answer> ::= < Diameter Header: 262, PXY >
< Session-Id >
{ Auth-Application-Id }
{ Result-Code }
{ Origin-Host }
{ Origin-Realm }
[ Acct-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 ]
* [ Proxy-Info ]
* [ AVP ]
5.0 Result-Code AVP Values
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This section defines new Result-Code [DIAMBASE] values that MUST be
supported by all Diameter implementations that conform to this
specification.
5.1 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.
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.
DIAMETER_ERROR_MIP_FILTER_NOT_SUPPORTED 4008
This error code is used by a mobility agent to indicate to
The home Diameter server that the requested packet filter
Rules cannot be supported.
5.2 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.
DIAMETER_ERROR_END_TO_END_MIP_KEY_ENCRYPTION 5025
This error is used by the AAAF / AAAH to inform that the
requested Mobile IP session keys could not be encrypted with
the CMS strong security application and therefore failed.
5.0 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.
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Due to space constraints, the short form IPFiltrRule is used to
represent IPFilterRule and DiamIdent is used to represent
DiameterIdentity.
+--------------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section | | |SHLD| MUST|MAY |
Attribute Name Code Defined Value Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
MIP-Filter-Rule 342 5.8 IPFiltrRule| M | P | | V | Y |
MIP-Auth-Input- 338 5.6.2 Unsigned32 | M | P | | V | Y |
Data-Length | | | | | |
MIP- 339 5.6.3 Unsigned32 | M | P | | V | Y |
Authenticator-Length | | | | | |
MIP- 340 5.6.4 Unsigned32 | M | P | | V | Y |
Authenticator-Offset | | | | | |
MIP-Candidate- 336 5.9 DiamIdent | M | P | | V | N |
Home-Agent-Host | | | | | |
MIP-Home-Agent- 348 5.11 DiamIdent | M | P | | V | N |
Host | | | | | |
MIP-FA-Challenge 344 5.7 OctetString| M | P | | V | Y |
MIP-Feature- 337 5.5 Unsigned32 | M | P | | V | Y |
Vector | | | | | |
MIP-Home-Agent- 334 5.4 Address | M | P | | V | Y |
Address | | | | | |
MIP-MN-AAA-Auth 322 5.6 Grouped | M | P | | V | Y |
MIP-MN-AAA-SPI 341 5.6.1 Unsigned32 | M | P | | V | Y |
MIP-Mobile-Node- 333 5.3 Address | M | P | | V | Y |
Address | | | | | |
MIP-Reg-Request 320 5.1 OctetString| M | P | | V | Y |
MIP-Reg-Reply 321 5.2 OctetString| M | P | | V | Y |
MIP-Originating- 347 5.10 Grouped | M | P | | V | Y |
Foreign-AAA | | | | | |
5.1 MIP-Reg-Request AVP
The MIP-Reg-Request AVP (AVP Code 320) is of type OctetString and
contains the Mobile IP Registration Request [MOBILEIP] sent by the
mobile node to the foreign agent.
5.2 MIP-Reg-Reply AVP
The MIP-Reg-Reply AVP (AVP Code 321) is of type OctetString and
contains the Mobile IP Registration Reply [MOBILEIP] sent by the home
agent to the foreign agent.
5.3 MIP-Mobile-Node-Address AVP
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The MIP-Mobile-Node-Address AVP (AVP Code 333) is of type Address and
contains the mobile node's home IP address.
5.4 MIP-Home-Agent-Address AVP
The MIP-Home-Agent-Address AVP (AVP Code 334) is of type Address and
contains the mobile node's home agent IP address.
5.5 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-Requested flag to one, it MUST set
the MN-HA-Key-Request flag to one. The MN-HA-Key-Request flag is also
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Diameter MIP November 2003
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 FA-HA key with the home
agent, the foreign agent 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.
5.6 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, MIPCHAL] 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 ]
5.6.1 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)
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should attempt to validate the Authenticator computed by the mobile
node over the Registration Request data.
5.6.2 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.
5.6.3 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).
5.6.4 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).
5.7 MIP-FA-Challenge AVP
The MIP-FA-Challenge AVP (AVP Code 344) is of type OctetString and
contains the challenge advertised by the foreign agent to the mobile
node. This AVP MUST be present in the AMR if the mobile node used the
RADIUS-style MN-AAA computation algorithm.
5.8 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. The packet filtering rules are set by the
AAAH by adding one or more MIP-Filter-Rule AVPs in the HAR if
destined for the home agent and/or in the AMA if destined for the
foreign agent.
5.9 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.
5.10 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
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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 ]
5.11 MIP-Home-Agent-Host AVP
The MIP-Home-Agent-Host AVP (AVP Code 348) if of type Grouped, and
contains the identity of the assigned Home Agent. If present in
the
AMR, the AAAH MUST copy the MIP-Home-Agent-Host AVP into the HAR.
MIP-Home-Agent-Host ::= < AVP Header: 348 >
{ Destination-Realm }
{ Destination-Host }
* [ AVP ]
6.0 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.
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.
6.1 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
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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.
6.2 Key Material vs. Session Key
As described in section 1.6, session keys and nonces are generated by
the AAAH and are transmitted to the home agent, foreign agent and
mobile node. Security associations destined for the home and foreign
agents are established via transmission of session keys and SPIs,
protected by transmission-level security as defined in [DIAMBASE].
Where it is necessary to protect the nonces, session keys, and SPIs
from untrusted Diameter agents, end-to-end security mechanisms are
required to eliminate the all Diameter Agents between the FA or HA
and the AAAH, as outlined above.
In [MIPKEYS] the mobile node security associations are established
via nonces transmitted to the mobile node via Mobile IP. To provide
the nonces, the AAAH must generate a random [RANDOM] value of at
least 128 bits [MIPKEYS]. The mobile node then uses the nonce to
derive the MN-HA and MN-FA session keys.
More details of the MN-HA and the MN-FA session key creation
procedure are found in [MIPKEYS].
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 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 128 bits for use as the Foreign-Home session key.
See sections 7.0 for details about the format of the AVPs used to
transport the session keys.
6.3 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.
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The distribution of the MN-HA key to the HA has been specified above.
The HA and AAAH establish a security association (IPSec or TLS) and
transport the key over that security association.
If no security association exists between the AAAH and the home
agent, and a security association cannot be established the AAAH MUST
return a Result-Code AVP with
DIAMETER_ERROR_END_TO_END_MIP_KEY_ENCRYPTION.
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 includes
the Mobile-Home session Key Material AVP into a MIP-MN-to-HA-Key AVP,
which is added to the HAR message, and delivered either to a local
home agent or a home agent in the visited network. The AAAH has to
rely on the home agent (that also understands Diameter) to transfer
the keying material (nonce) 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.
The AAAH parses the HAA message, transforms it into an AMA containing
an MIP-Reg-Reply AVP, and sends the AMA message to the foreign agent.
The foreign agent then uses 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, and a session key, which is added
to the MIP-HA-to-MN-Key AVP. These AVPs are delivered to the home
agent in an HAR message. The home agent retains the session key for
its own use, and copies the key material (nonce) from the MIP-MN-to-
HA-Key AVP into a Generalized MN-HA Key Reply extension, which is
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 includes the Registration Reply
message and extensions into a MIP-Reg-Reply AVP as part of the HAA
message to be sent back to the AAA server.
6.4 Distributing the Mobile-Foreign Session Key
The Mobile-Foreign session key material (nonce) is also generated by
AAAH (upon request) and is added to the MIP-MN-to-FA-Key Material
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 Material From AAA Request Subtype extension. The
AAAH includes the session key in the MIP-FA-to-MN-Key AVP in the AMA,
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Diameter MIP November 2003
to be used by the foreign agent in the computation of the Mobile-
Foreign authentication extension.
6.5 Distributing the Foreign-Home Session Key
If the foreign agent requests a foreign home key, it also includes a
MIP-HA-to-FA-SPI AVP in the AMR to convey the SPI to be used by the
home agent for this purpose. The AAAH generates the Foreign-Home
session key and distributes it to both the HA and the FA over
respective security associations to each using the MIP-HA-to-FA and
MIP-FA-to-HA-Key AVPs. The HA conveys the SPI the FA should use in
the HAA; the AAAH later includes that in the MIP-FA-HA-Key AVP, along
with the session key.
Refer to Figures 3, 4, 9, and 10 for the messages involved.
7.0 Key Distribution Center (KDC) AVPs
The Mobile-IP protocol defines a set of security associations shared
between the mobile node, foreign agent and home agent. These three
security associations (Mobile-Home, Mobile-Foreign, and Foreign-Home)
can be dynamically created by the AAAH, and has previously been
described in section 1.6 and 5.2. AAA servers supporting the Diameter
Mobile IP Application MUST implement the KDC AVPs defined in this
document.
The names of the KDC AVPs indicate the two entities sharing the
security association defined by the key or the 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
material (nonce), which the mobile node will use to derive the
Mobile-Home Key, and the MIP-HA-to-MN-Key AVP contains the Mobile-
Home key for the home agent.
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.
[Editor note: The following table has errors.]
+--------------------------+
| AVP Flag Rules |
|----+-----+----+-----|----+
AVP Section | | |SHLD| MUST|MAY |
Attribute Name Code Defined Value Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
MIP-Algorithm- 345 7.8 Enumerated | M | P | | V | Y |
Type | | | | | |
MIP-FA-to-HA-Key 328 7.2 Grouped | M | P | | V | Y |
MIP-FA-to-HA-SPI 318 7.11 Unsigned32 | M | P | | V | Y |
MIP-HA-to-FA-SPI 3** 7.14 Unsigned32 | M | P | | V | Y |
MIP-FA-to-MN-Key 326 7.1 Grouped | M | P | | V | Y |
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Diameter MIP November 2003
MIP-FA-to-MN-SPI 319 7.10 Unsigned32 | M | P | | V | Y |
MIP-HA-to-FA-Key 329 7.3 Grouped | M | P | | V | Y |
MIP-HA-to-MN-Key 332 7.4 Grouped | M | P | | V | Y |
MIP-Key-Lifetime 367 7.13 Unsigned32 | M | P | | V | Y |
MIP-Key-Material 335 7.12 OctetString| M | P | | V | Y |
MIP-MN-to-FA-Key 325 7.5 Grouped | M | P | | V | Y |
MIP-MN-to-HA-Key 331 7.6 Grouped | M | P | | V | Y |
MIP-Replay-Mode 346 7.9 Enumerated | M | P | | V | Y |
MIP-Session-Key 343 7.7 OctetString| M | P | | V | Y |
7.1 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 ]
7.2 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 ]
7.3 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 ]
7.4 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:
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Diameter MIP November 2003
MIP-HA-to-MN-Key ::= < AVP Header: 332 >
{ MIP-Algorithm-Type }
{ MIP-Replay-Mode }
{ MIP-Session-Key }
* [ AVP ]
7.5 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 (a nonce), 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 ]
7.6 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 ]
7.7 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.
7.8 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:
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Diameter MIP November 2003
1 HMAC-MD5 [HMAC]
2 HMAC-SHA-1 [HMAC]
7.9 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
7.10 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.
7.11 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.
7.12 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.
7.13 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
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Diameter MIP November 2003
applies is still active, either the session key MUST be changed or
the or the session MUST be terminated.
7.14 MIP-HA-to-FA-SPI AVP
The MIP-HA-to-FA-SPI AVP (AVP Code 3**) is of type Unsigned32, and
contains the Security Parameter Index the home agent is to use to
refer to the session key it shares with the foreign 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-HA-to-FA-SPI member of the grouped MIP-HA-to-FA-Key AVP.
The FA should provide this to the AAAH in the AMR, as it should
control the assignment of this SPI.
8.0 Accounting AVPs
[Editor note: Will anyone use the AVPs of this section? Deployments
using MIP, e.g., 3GPP2 have VSAs for this purpose.]
8.1 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. This AVP MUST be included in all Accounting-Request messages
and MAY be present in the corresponding Accounting-Answer messages as
well.
8.2 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. This AVP MUST be included in all Accounting-Request
messages and MAY be present in the corresponding Accounting-Answer
messages as well.
8.3 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. This AVP MUST be
included in all Accounting-Request messages and MAY be present in the
corresponding Accounting-Answer messages as well.
8.4 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. This
AVP MUST be included in all Accounting-Request messages and MAY be
present in the corresponding Accounting-Answer messages as well.
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Diameter MIP November 2003
8.5 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. This AVP MUST
be included in all Accounting-Request messages and MAY be present in
the corresponding Accounting-Answer messages as well.
8.6 Event-Timestamp AVP
The Event-Timestamp (AVP Code 55) is of type Time, and MAY be
included in an Accounting-Request message to record the time that
this event occurred on the mobility agent, in seconds since January
1, 1970 00:00 UTC.
9.0 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.
9.1 Mobile IP Command AVP Table
The table in this section is limited to the Command Codes defined in
this specification.
+-----------------------+
| Command-Code |
|-----+-----+-----+-----+
Attribute Name | AMR | AMA | HAR | HAA |
------------------------------|-----+-----+-----+-----+
Authorization-Lifetime | 0-1 | 0-1 | 1 | 0 |
Auth-Application-Id | 1 | 1 | 1 | 1 |
Auth-Session-State | 0-1 | 0-1 | 1 | 0 |
Acct-Multi-Session-Id | 0-1 | 0-1 | 0 | 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 | 0-1 | 0 |
MIP-Home-Agent-Host | 0-1 | 0 | 0-1 | 0 |
MIP-Originating-Foreign-AAA | 0-1 | 0 | 0-1 | 0 |
MIP-FA-Challenge | 0-1 | 0 | 0 | 0 |
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Diameter MIP November 2003
MIP-FA-to-HA-Key | 0 | 0-1 | 0-1 | 0 |
MIP-FA-to-HA-SPI | 0 | 0 | 0 | 0-1 |
MIP-HA-to-FA-SPI | 0 | 0 | 0 | 0-1 |
MIP-MN-to-FA-Key | 0 | 0-1 | 0 | 0 |
MIP-FA-to-MN-SPI | 0 | 0 | 0 | 0-1 |
MIP-MN-to-FA-SPI | 0 | 0 | 0 | 0-1 |
MIP-MN-to-HA-Key | 0 | 0-1 | 0 | 0 |
MIP-HA-to-MN-SPI | 0 | 0 | 0 | 0-1 |
MIP-MN-to-HA-SPI | 0 | 0 | 0 | 0-1 |
MIP-Feature-Vector | 0-1 | 0-1 | 1 | 0 |
MIP-Filter-Rule | 0 | 0+ | 0+ | 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-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 |
Origin-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 |
User-Name | 1 | 0-1 | 1 | 0-1 |
------------------------------|-----+-----+-----+-----|
9.2 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 |
Acct-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 |
Event-Timestamp | 0-1 | 0 |
-------------------------------------|------+------+
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Diameter MIP November 2003
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 [DIAMBASE]. See section 2.0 for the
assignment of the namespace in this specification.
10.2 AVP Codes
This specification assigns the values 318-348 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.
10.3 Result-Code AVP Values
This specification assigns the values 4005-4008, and 5024-5025 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.
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,
aslisted in section 4.5. The remaining bits should only be assigned
via Standards Action [IANA].
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 [IANA].
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 [IANA].
10.7 Application Identifier
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Diameter MIP November 2003
This specification assigns the value four (4) to the Application
Identifier namespace defined in [DIAMBASE]. See section 1.8 for more
information.
11.0 Security Considerations
This specification describes a Mobile IP Diameter Application for
authenticating and authorizing a Mobile IP mobile node. The
authentication algorithm used is dependent upon the transforms used
within the Mobile IP protocol, and [MIPCHAL]. This specification,
conjunction with [MIPKEYS] also defines a method by which the home
Diameter server can create and distribute session keys and nonces for
use in authenticating and integrity-protecting Mobile IP registration
messages [MOBILEIP]. The key distribution is asymmetric since
communication with the mobile node occurs via the Mobile IP protocol
[AAAKEY, MOBILEIP], while communication to the Home Agent and Foreign
Agent occurs via the Diameter protocol. Where untrusted Diameter
agents are present, end-to-end security MUST be used Between the AAAH
and the HA/FA.
Nonces are sent to the mobile node, which are used to generate the
session keys via the HMAC-MD5 one-way function. If the nonces are
compromised, then the pre-shared key between the mobile node and the
home Diameter server would be vulnerable to an offline dictionary
attack. To prevent this, the pre-shared key between the mobile node
and the home Diameter server SHOULD be a randomly chosen quantity of
at least 96 bits.
Since the session key is determined by the long-term secret and the
nonce, the nonce SHOULD be temporally and globally unique; if the
nonce were to repeat, then so would the session key. To prevent this,
a nonce is strongly recommended to be random [RANDOM] value of at
least 128 bits. The long-term secret between the MN and HA MUST be
periodically refreshed, to guard against recovery of the long-term
secret due to nonce reuse or other factors. This is accomplished
using out-of-band mechanisms, which are not specified in this
document.
It should also be noted that it is not recommended to set the MIP-
Session-Key AVP value equal to zero, since keeping session keys for a
long time (no refresh) increases the level of vulnerability.
12.0 References
12.1 Normative
[DIAMBASE] P. Calhoun, H. Akhtar, J. Arkko, E. Guttman, A.
Rubens,
"Diameter Base Protocol", draft-ietf-aaa-diameter-
17.txt (editor queue status), December 2002.
[IANA] Narten, Alvestrand, "Guidelines for Writing an IANA C
Calhoun Standards Track - March 2003 37
Diameter MIP November 2003
Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998
[MOBILEIP] C. Perkins, Editor. IP Mobility Support. RFC 3344,
August 2002.
[MIPCHAL] C. Perkins, P. Calhoun, "Mobile IP Challenge/Response
Extensions", draft-ietf-mip4-rfc3012bis-00.txt.
November 2003.
[NAI] B. Aboba, M. Beadles "The Network Access Identifier."
RFC 2486. January 1999.
[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-mipv4-aaa-key-00.txt,
IETF work in progress, November 2003.
[AAANAI] F. Johansson, T.Johansson, "AAA NAI for Mobile IP
Extension", draft-mobileip-aaa-nai-05.txt, IETF work
In progress, March 2003.
12.2 Informative
[MIPREQ] S. Glass, S. Jacobs, C. Perkins, "Mobile IP
Authentication, 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
Protocols", RFC 2477, January 1999.
[MIPNAI] P. Calhoun, C. Perkins, "Mobile IP Network Address
Identifier Extension", RFC 2794, March 2000.
[RANDOM] D. Eastlake, 3rd, S. Crocker, and J. Schiller.
Radomness Recommendations for Security. RFC 1750,
Internet Engineering Task Force, December 1994.
13.0 Acknowledgements
The authors would like to thank Nenad Trifunovic, Haseeb Akhtar and
Pankaj Patel for their participation in the pre-IETF Document Reading
Calhoun Standards Track - March 2003 38
Diameter MIP November 2003
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-
X 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, Johan Johansson. In addition, general text
for use with the redirect server were borrowed from Diameter-EAP text
by Pasi Eronen.
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.
14.0 Authors' Addresses
Questions about this memo can be directed to:
Pat Calhoun
Airespace
110 Nortech Parkway
San Jose, CA 95154
USA
Phone: +1 408-635-2023
Email: pcalhoun@airespace.com
Tony Johansson
Bytemobile, Inc
2029 Stierlin Court
Mountain View, California 94043
USA
Phone: +1 650-641-7817
Fax: +1 650-641-7701
E-Mail: tony.johansson@bytemobile.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
Tom Hiller
Lucent Technologies
1960 Lucent Lane
Calhoun Standards Track - March 2003 39
Diameter MIP November 2003
Naperville, IL 60566
USA
Phone: +1 630-979-7673
E-mail: tomhiller@lucent.com
Calhoun Standards Track - March 2003 40
Diameter MIP November 2003
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are included on all such copies and derivative works. However, this
document 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
developing 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
1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996.
2 Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997
Calhoun Standards Track - March 2003 41
| PAFTECH AB 2003-2026 | 2026-04-21 19:11:08 |