MIP4 Working Group H. Deng
Internet-Draft Hitachi (China)
Expires: December 25, 2006 H. Levkowetz
Ericsson Research
V. Devarapalli
Azaire Networks
S. Gundavelli
Cisco Systems
B. Haley
Hewlett-Packard Company
June 23, 2006
Generic Notification Message for Mobile IPv4
draft-deng-mip4-generic-notification-message-02.txt
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document specifies protocol enhancements that allow Mobile IPv4
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entities to send and receive explicit notification messages using a
new Mobile IPv4 type designed for this purpose.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Scenarios Requiring a Notification Message . . . . . . . . . . 5
3.1. Home Agent Initiates a Notification to the Mobile Node . . 5
3.1.1. Foreign Agent Care-of Address . . . . . . . . . . . . 5
3.1.2. Co-located Care-of Address . . . . . . . . . . . . . . 5
3.2. Foreign Agent Initiates a Notification to the Mobile
Node . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Home Agent Initiates a Notification to the Foreign
Agent . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Generic Notification Message and Considerations . . . . . . . 7
4.1. Generic Notification Message . . . . . . . . . . . . . . . 7
4.2. Generic Notification Acknowledgment Message . . . . . . . 9
4.3. Mobile Node Consideration . . . . . . . . . . . . . . . . 11
4.3.1. Receiving Generic Notification Messages . . . . . . . 12
4.3.2. Sending Generic Notification Acknowledgement
Message . . . . . . . . . . . . . . . . . . . . . . . 12
4.4. Foreign Agent Consideration . . . . . . . . . . . . . . . 13
4.4.1. Receiving Generic Notification Message . . . . . . . . 13
4.4.2. Sending Generic Notification Acknowledgement
Message . . . . . . . . . . . . . . . . . . . . . . . 14
4.4.3. Sending Generic Notification Messages . . . . . . . . 15
4.5. Home Agent Consideration . . . . . . . . . . . . . . . . . 15
4.5.1. Sending Generic Notification Message . . . . . . . . . 15
4.5.2. Receiving Generic Notification Acknowledgement
Messages . . . . . . . . . . . . . . . . . . . . . . . 16
4.5.3. Receiving Generic Notification Messages . . . . . . . 17
4.5.4. Sending Generic Notification Acknowledgement
Messages . . . . . . . . . . . . . . . . . . . . . . . 17
5. Usage Example . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1. Revocation Extension . . . . . . . . . . . . . . . . . . . 18
5.2. Generic String Extension . . . . . . . . . . . . . . . . . 18
6. Security Considerations . . . . . . . . . . . . . . . . . . . 19
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Normative References . . . . . . . . . . . . . . . . . . . 21
8.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
Intellectual Property and Copyright Statements . . . . . . . . . . 23
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1. Introduction
In some situations, there is a need for Mobile IPv4 entities, such as
the home agent, foreign agent and mobile node to send and receive
asynchronous notification events during a mobility session. The base
Mobile IP Specification [RFC3344] does not have a provision for this.
This document defines a generic message and a notification model that
can be used by Mobile IPv4 entities to send various notifications.
However, this specification does not define any specific notification
message or the actions that the receiving entity is required to
perform on receiving that message. Specific extensions and the
corresponding handler actions are outside the scope of this document.
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2. Terminology
It is assumed that the reader is familiar with the terminology used
in [RFC3543], [RFC3344]. In addition, the following terms are
defined:
Notification Message
A message from a mobility agent to a mobile node or other mobility
agent to asynchronously notify it about an event that is relevant
to the mobility service it is currently providing.
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, [RFC2119].
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3. Scenarios Requiring a Notification Message
There are several scenarios where a mobility agent could initiate
notification events. Some of these are described in the following
sections.
3.1. Home Agent Initiates a Notification to the Mobile Node
The home agent may wish to notify a mobile node about events such as
load balancing, where the home agent wants to move some of the
registered mobile nodes to other home agents; service termination due
to end of prepaid time; or service interruption due to system
maintenance. If the event requires some specific response from the
mobile node, a new extension and specification needs to be defined
for this. On the other hand, the notification could be intended for
the user, for example, the message string extension [MIP4-STRING].
3.1.1. Foreign Agent Care-of Address
In this case, the home agent cannot directly notify the mobile node,
but must send the notification via the foreign agent.
+----+ notification +----+ notification +----+
| MN |<================| FA |<=============| HA |
+----+ +----+ +----+
Figure 1: Home Agent notifies Mobile Node through Foreign Agent
3.1.2. Co-located Care-of Address
In this case, the mobile node has registered with the home agent
directly, so the notification message can go directly to the mobile
node.
The notification mechanism as specified here does not support the
case of Co-located CoA mode with registration through a foreign agent
(due to the 'R' bit being set in the foreign agent's advertisement
messages).
+----+ notification +----+
| MN |<===================================| HA |
+----+ +----+
Figure 2: Home Agent directly notifies Mobile Node
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3.2. Foreign Agent Initiates a Notification to the Mobile Node
There are two cases where a foreign agent may send notification
messages to a mobile node, one where it is relaying a message, the
other where the notification is triggered by a message from another
network entity, for example a AAA node. (notification messages
between a AAA entity and the foreign agent could be based on RADIUS
or Diameter, but this is out of scope for this document). If the
notification is initiated by a foreign agent, the foreign agent may
need to also notify the home agent about the event.
+----+ notification +----+ notification +--------+
| MN |<================| FA |<=============| AAA/HA |
+----+ +----+ +--------+
|| notification +----+
================>| HA |
+----+
Figure 3: Foreign Agent notifies Mobile Node
3.3. Home Agent Initiates a Notification to the Foreign Agent
The home agent may also need to send a notification to the foreign
agent, but not to the mobile node, as illustrated below:
+----+ notification +----+
| FA |<=============| HA |
+----+ +----+
Figure 4: Home Agent notifies Foreign Agent
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4. Generic Notification Message and Considerations
This section describes in detail the generic notification message,
generic notification acknowledgement message, and some considerations
related to the handling of these messages in the mobile node, foreign
agent and home agent.
4.1. Generic Notification Message
A generic notification message is sent by a mobility agent to inform
another mobility agent, or a mobile node, of MIP-related information.
These messages must use the same IP and UDP headers as any previous
Registration Request or Reply message to the same entity. The
generic notification message is defined as follows:
IP Fields:
Source Address Sender's address.
Destination Address Receiver's address.
UDP Fields:
Source Port variable.
Destination Port Same as the last Registration Reply/Request
message.
The UDP header is followed by the Mobile IP fields shown below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Subtype |M|H|A| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Care-of Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Identification +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions...
+-+-+-+-+-+-+-+-+-+-+-+-+-
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Type (TBD)
Subtype
This field describes the particular type of notification which is
carried in the notification message.
M
This bit indicates whether the receiver of the notification is a
mobile node
Set to "1" to indicate that if the message is intended for the
mobile node.
Set to "0" to indicate that if the message is not intended for the
mobile node.
H
This bit indicates whether the sender of this message is the home
agent or the foreign agent.
Set to "1" to indicate that the sender is the home agent.
Set to "0" to indicate that the sender is the foreign agent.
A
This bit indicates whether the notification message MUST be
acknowledged by the recipient.
Set to "1" to indicate that acknowledgement is required.
Set to "0" to indicate that acknowledgement is optional.
Reserved
MUST be sent as 0, and ignored when received.
Home Address
The home IP address of the mobile node.
Home Agent Address
The IP address of the mobile node's home agent.
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Care-of Address
The mobile node's care-of address, either the co-located care-of
address or the foreign agent care-of address.
Identification
A 64-bit number, constructed by the sender, used for matching
Generic Notification with Generic Notification Acknowledgement,
and for protecting against replay attacks of notification
messages. See Sections 5.4 and 5.7 of [RFC3344].
Extensions
The fixed portion of the Generic Notification Message is followed
by one or more extensions which may be used with this message, and
by one or more authentication extensions (as defined in Section
3.5 of [RFC3344]). See Sections 3.6.1.3 and 3.7.2.2 of [RFC3344]
for information on the relative order in which different
extensions, when present, must be placed in a Generic Notification
Message.
4.2. Generic Notification Acknowledgment Message
A generic notification acknowledgement message is sent by mobility
agents or mobile nodes to indicate the successful receipt of a
generic notification message.
IP Fields:
Source Address Typically copied from the destination
address of the Generic Notification to which
the agent is replying.
Destination Address Copied from the source address of the
Generic Notification to which the agent is
replying.
UDP Fields:
Source Port variable.
Destination Port Copied from the source port of the
corresponding Generic Notification.
The UDP header is followed by the Mobile IP fields shown below:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Subtype |M|H| Reserved | Status |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Care-of Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Identification +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions...
+-+-+-+-+-+-+-+-+-+-+-+-+-
Type (TBD)
Subtype
This field specifies the particular type of notification
acknowledgement message.
M
This bit indicates whether the sender of this message is the
mobile node or not.
Set to "1" to indicate that the sender is the mobile node.
Set to "0" to indicate that the sender is not the mobile node.
H
This bit indicates whether the receiver of this notification
acknowledgement is the home agent or not.
Set to "1" to indicate that the receiver is the home agent.
Set to "0" to indicate that thee receiver is not the home agent.
Reserved
MUST be sent as 0, and ignored when received.
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Status
If the Generic Notification Message was received without error,
this field is set to zero. However, if there is an error in
reception, the field is nonzero with the following allowable codes
defined in section 3.4 of [RFC3344].
Home Address
The home IP address of the mobile node.
Home Agent Address
The IP address of the sender's home agent.
Care-of Address
The mobile node's care-of address, either the co-located care-of
address or the foreign agent care-of address.
Identification
A 64-bit number used for matching Generic Notification with
Generic Notification Acknowledgement, and for protecting against
replay attacks of generic notification messages. The value is
based on the Identification field from the Generic Notification
message from the sender, and on the style of replay protection
used in the security context between the receiver and sender
(defined by the mobility security association between them, and
SPI value in the authorization-enabling extension). See Sections
5.4 and 5.7 of [RFC3344].
Extensions
The fixed portion of the generic notification acknowledgement
message is followed by one or more of the Extensions listed in
Section 3.5 of [RFC3344]. See Sections 3.6.1.3 and 3.7.2.2 of
[RFC3344] for information on the relative order in which different
extensions, when present, MUST be placed in a Generic Notification
message.
4.3. Mobile Node Consideration
It is possible that the mobile node MAY receive a generic
notification message from a foreign agent or home agent. Both in the
case of FA-CoA and Co-located CoA, the mobile node MAY reply with a
Generic Notification Acknowledgement message based on the "A" flag in
the notification message.
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4.3.1. Receiving Generic Notification Messages
When the mobile node is using FA-CoA and receives a Notification
message, if the "H" flag is set, it means that the notification
message came from the home agnet. If the "H" flag is not set, the
notification came from the foreign agent.
In either case, the Mobile-Foreign Authentication extension MUST be
used, and the mobile node MUST check the Authenticator value in the
Extension. If no Mobile-Foreign Authentication Extension is found,
or if more than one Mobile-Foreign Authentication Extension is found,
or if the Authenticator is invalid, the mobile node MUST silently
discard the Notification message.
If this notification message came from a foreign agent and the mobile
node accepts the foreign agent's generic notification message, it
will process the notification extension according to the specific
rules for that extension. After that, the mobile node MAY reply with
a Generic Notification Acknowledgement message back to the foreign
agent. If the "A" flag is set in the notification message, then the
mobile node MUST send the acknowledgement.
If this notification message came from the home agent, relayed by the
foreign agent, or is a Co-located CoA, the Mobile-Home Authentication
extension MUST be checked and the mobile node MUST check the
Authenticator value in the Extension. If no Mobile-Home
Authentication Extension is found, or if more than one Mobile-Home
Authentication Extension is found, or if the Authenticator is
invalid, the mobile node MUST silently discard the Notification
message. If the mobile node accepts the home agent's generic
notification message, it will process it according to the specific
rules for that extension. After that, the mobile node MAY reply with
a Generic Notification Acknowledgement message back to the home agent
based on the "A" flag in the notification message.
4.3.2. Sending Generic Notification Acknowledgement Message
Both in the case of a Co-located CoA and FA-CoA, the mobile node MAY
reply with a Generic Notification Acknowledgement Message based on
the "A" flag in the notification message as follows:
In the case of FA-CoA, The source address is the mobile node's
address, the destination address is the foreign agent address.
If the notification message was initiated from the foreign agent to
the mobile node ("M" flag is set to "1", "H" flag is set to "0"), the
ordering of the extension is: any non-authentication Extensions used
only by the foreign agent, followed by The Mobile-Foreign
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Authentication extension defined in section 3.5.3 of [RFC3344].
! If the notification message was initiated from the home agent to
the mobile node ("M" flag is set to "1", "H" flag is set to "1"), the
ordering of the extension is: any non-authentication Extensions used
only by the foreign agent, followed by The Mobile-Foreign
Authentication extension defined in section 3.5.3 of [RFC3344],
followed by any non-authentication Extensions used only by the home
agent, followed by the Mobile-Home Authentication extension defined
in section 3.5.2 of [RFC3344]
In the case of a FA-CoA, the source address is the mobile node's CoA
address and the destination address is the home agent's address ("M"
flag is set to "1", "H" flag is set to "1"), the ordering of the
extension is: the Generic Notification extension, followed by any
non-authentication extension expected to be used by home agent,
followed by the Mobile-Home Authentication Extension defined in
section 3.5.2. of [RFC3344].
4.4. Foreign Agent Consideration
The foreign agent cannot only relay generic notification message from
the home agent and mobile node, but it can also initiate a generic
notification message to the mobile node or home agent, but only when
there is a binding for the mobile node. This means that the
messaging is between the entities in the binding relation.
4.4.1. Receiving Generic Notification Message
If the foreign agent receives a notification message, and the "M"
flag is set to "1", it means that the home agent is asking the
foreign agent to relay the message to the mobile node. Otherwise, it
means that the target of the notification is the foreign agent.
If the "M" flag is set to "0", the Foreign-Home Authentication
extension MUST be checked, and the foreign agent MUST check the
Authenticator value in the Extension. If no Foreign-Home
Authentication Extension is found, or if more than one Foreign-Home
Authentication Extension is found, or if the Authenticator is
invalid, the foreign agent MUST silently discard the Notification
message. If foreign agent accepts the home agent's generic
notification message, it will process it based on the specific rules
for that extension. The foreign agent MAY then reply with a Generic
Notification Acknowledgement message back to the home agent based on
the "A" flag in the notification message.
If the "M" flag is set to "1", the Foreign-Home Authentication
extension MUST be checked, and the foreign agent MUST check the
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Authenticator value in the Extension. If no Foreign-Home
Authentication Extension is found, or if more than one Foreign-Home
Authentication Extension is found, or if the Authenticator is
invalid, the foreign agent MUST silently discard the Notification
message. If foreign agent accepts the home agent's generic
notification message, it MUST relay the Generic Notification to the
mobile node's home address as specified in the Home Address field of
the Generic Notification. The foreign agent MUST NOT modify any of
the fields beginning with the fixed portion of the Generic
Notification message through and including the Mobile-Home
Authentication Extension or other authentication extension supplied
by the home agent as an authorization-enabling extension for the
mobile node. Furthermore, the foreign agent MUST process and remove
any Extensions following the Mobile-Home Authentication Extension and
MAY append any of its own non-authentication Extensions of relevance
to the mobile node, if applicable, and MUST append the Mobile-Foreign
Authentication Extension, if the foreign agent shares a mobility
security association with the Mobile Node.
4.4.2. Sending Generic Notification Acknowledgement Message
The foreign agent may need to either relay a Generic Notification
Acknowledgemnt message between the mobile node and the home agent or
send one as a response to a notification messsage that was sent to
it. In both cases, the Generic Notification Acknowledgement Message
is defined as follows:
The source address is the foreign agent address, the destination
address is home agent address.
if the foreign agent is only relaying this message to the home agent,
the foreign agent it MUST NOT modify any of the fields beginning with
the fixed portion of the Generic Notification Acknowledgement through
and including the Mobile-Home Authentication Extension or other
authentication extension supplied by the home agent as an
authorization-enabling extension for the mobile node. Furthermore,
the foreign agent MUST process and remove any Extensions following
the Mobile-Home Authentication Extension and MAY append any of its
own non-authentication Extensions of relevance to the home agent, if
applicable. It MUST also append the Foreign-Home Authentication
Extension, if the foreign agent shares a mobility security
association with the home agent.
If the notification message is from the home agent to the foreign
agent then flag "M" is set to "0" and flag "H" is set to "1" and the
ordering of the extension is: any non-authentication Extensions used
only by the home agent, followed by The Foreign-Home Authentication
extension defined in section 3.5.4 of [RFC3344].
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4.4.3. Sending Generic Notification Messages
If the foreign agent is initiating a notification the mobile node
using the generic notification message, it MAY also notify the home
agent as well.
In the message to the mobile node, the source address is the foreign
agent address, the destination address is the mobile node's address,
the "M" flag is set to "1" and the "H" flag is set to "0", and the
ordering of the extension is: the notification extension, followed by
any non-authentication Extensions used only by the mobile node,
followed by The Mobile-Foreign Authentication extension defined in
section 3.5.3 of [RFC3344]. Computing Authentication Extension
Values is the same as section 3.5.1 of [RFC3344] except the payload
is the notification other than registration.
In the message to the home agent, the source address is the foreign
agent's address, the destination address is the home agent's address,
the "M" flag is set to "0" and the "H" flag is set to "0", The
ordering of the extension is: notification extension, followed by any
non-authentication Extensions used only by the home agent, followed
by The Foreign-Home Authentication extension defined in section 3.5.4
of [RFC3344]. Computing Authentication Extension Values is the same
as section 3.5.1 of [RFC3344] except the payload is the notification
other than registration.
4.5. Home Agent Consideration
Home agent MAY initiate a generic notification message to both the
mobile node and foreign agent, and it also MAY receive a generic
notification acknowledgement message from both the foreign agent and
mobile node. The home agent also MAY receive a generic notification
message from the foreign agent, but only when there is a binding for
a mobile node. It can send a message to the mobile node or to the
registered foreign agent in the path. This means that the messaging
is between the entities in the binding relation. If the home agent
receives a notification message from a foreign agent and there is no
corresponding mobile node registration, the home agent should drop
the notification message.
4.5.1. Sending Generic Notification Message
In the case of FA CoA, the home agent may either send a notification
message to notify the foreign agent, or have the foreign agent relay
the notification message to the mobile node if the mobile node needs
to the notified.
if the message from the home agent to the foreign agent, the source
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address is home agent's address, the destination address is the
foreign agent's address
if the foreign agent is working only as a relay agent, the "M" flag
is set to "1" and the "H" flag is set to "1", and the ordering of the
extension is: the notification extension, followed by any non-
authentication extension expected to be used by mobile node, followed
by Mobile-Home Authentication Extension defined in section 3.5.2. of
[RFC3344], followed by any non-authentication Extensions used only by
the foreign agent, followed by The Foreign-Home Authentication
extension defined in section 3.5.4 of [RFC3344]. Computing
Authentication Extension Values is the same as section 3.5.1 of
[RFC3344].
if the foreign agent is the target of this notification message, then
the "M" flag is set to "0" and the "H" flag is set to "1", The
ordering of the extension is: the notification extension, followed by
any non-authentication Extensions used only by the foreign agent,
followed by The Foreign-Home Authentication extension defined in
section 3.5.4 of [RFC3344]. Computing Authentication Extension
Values is the same as section 3.5.1 of [RFC3344].
4.5.2. Receiving Generic Notification Acknowledgement Messages
In the case of FA-CoA, if the home agent receives this message, and
the "M" flag is set to "1", it means that the notification
acknowledgement message came from mobile node, otherwise it came from
the foreign agent. The Foreign-Home Authentication extension MUST be
checked, and the home agent MUST check the Authenticator value in the
Extension. If no Foreign-Home Authentication Extension is found, or
if more than one Foreign-Home Authentication Extension is found, or
if the Authenticator is invalid, the home agent MUST silently discard
the Notification Acknowledgement message.
if the "M" flag is set to "0", and the home agent accepted this
message, and the Status field indicates that the notification was
accepted by the foreign agent, the home agent MAY also process it
based on the notification event.
if the "M" flag is set to "0", and the home agent accepted this
message, the Mobile-Home Authentication extension MUST be checked,
and the home agent MUST check the Authenticator value in the
Extension. If no Mobile-Home Authentication Extension is found, or
if more than one Mobile-Home Authentication Extension is found, or if
the Authenticator is invalid, the home agent MUST silently discard
the Notification Acknowledgement message. if the home agent accepted
this message, and the Status field indicates that the notification
was accepted by the mobile node, home agent MAY also process it based
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on the notification event.
In the case of Co-located CoA, if the home agent received this
message, the Mobile-Home Authentication extension MUST be checked,
and the home agent MUST check the Authenticator value in the
Extension. If no Mobile-Home Authentication Extension is found, or
if more than one Mobile-Home Authentication Extension is found, or if
the Authenticator is invalid, the home agent MUST silently discard
the Notification Acknowledgement message. For all Generic
Notification Acknowledgement messages containing a Status Code
indicating status from the mobile node, If the Status field indicates
that the notification was accepted by the mobile node, home agent MAY
process it based on the notification event.
4.5.3. Receiving Generic Notification Messages
the home agent MAY receive generic notification messages which are
sent from the foreign agent. When the home agent receives this
message, and the Foreign-Home Authentication extension MUST be
checked, the home agent MUST check the Authenticator value in the
Extension. If no Foreign-Home Authentication Extension is found, or
if more than one Foreign-Home Authentication Extension is found, or
if the Authenticator is invalid, the home agent MUST silently discard
the Notification message. If home agent accepts the foreign agent's
generic notification message, it will process it based on the
notification extension. Furthermore, the home agent MAY reply with a
Generic Notification Acknowledgement message back to the foreign
agent based on the "A" flag in the notification message.
4.5.4. Sending Generic Notification Acknowledgement Messages
If the generic notification message came from the foreign agent only,
the home agent MAY reply with a generic notification acknowledgement
message to the foreign agent based on the "A" flag in the
notification message. if the "A" flag is set in the notification
message, then the home agent must send a Notification Acknowledgement
message. The message is as follows: The source address is home
agent's address, the destination address is the foreign agent's
address, the "M" flag is set to "0" and the "H" flag is set to "0".
The ordering of the extension is: any non-authentication Extensions
used only by the foreign agent, followed by The Foreign-Home
Authentication extension defined in section 3.5.4 of [RFC3344].
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5. Usage Example
There are several applications that could use this generic
notification message. for example, during handover between CDMA 2000
1x EV-DO and Wireless LAN, the PPP resource of CDMA side have to be
removed on the foreign agent (PDSN) to avoid over-charging
subscribers. Other applications such as registration revocation,
home agent switch over, NEMO prefix changes, and service or billing
related events.
Here we give a example of using revocation extension and describe
some possible event which could use the generic string extension
based on this notification mechanism also. There is also the
possibility that this notification message could carry many
extensions at once. A new VSE extension could be defined to support
this notification message.
5.1. Revocation Extension
If an agent would like to notify another agent about registration
revocation [RFC3543], it could easily be carried by a generic
notification message and generic notification acknowledgement. One
would just specify the exact number of "Subtype" in this two
messages.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Type | Length |I| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
5.2. Generic String Extension
In some case, the home agent or foreign agent needs to notify mobile
node about service termination due to the end of prepaid time, or
service interruption due to system maintenance. This information
could be defined based on a string which is recognized by mobile node
easily. An example would be "Maintenance Stopping", "Prepaid
Expire". These string MUST be strictly defined so they could be
easily understood by all of the network entities. "Subtype" number
will be decided by working group.
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6. Security Considerations
Mobile IP Generic Notification and Generic Notification
Acknowledgement are authenticated, and the authentication verified by
the recipient.
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7. IANA Considerations
This document describes two new messages, the Generic Notification
message, section 4.1 and the Generic Notification Acknowledgement
message, section 4.2. These two messages should be allocated from
the same address space used by the Registration Request and
Registration Reply messages in [RFC3344]
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8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
[RFC3543] Glass, S. and M. Chandra, "Registration Revocation in
Mobile IPv4", RFC 3543, August 2003.
8.2. Informative References
[MIP4-STRING]
Sastry, V., Leung, K., and A. Patel, "Mobile IPv4 Message
String Extension", Jan 2006,
<draft-mip4-message-string-ext-00(work in progress)>.
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Authors' Addresses
Hui Deng
Hitachi (China)
Beijing Fortune Bldg. 1701
5 Dong San Huan Bei-Lu
Chao Yang District
Beijing 100004
China
Email: hdeng@hitachi.cn
Henrik Levkowetz
Ericsson Research
Torshamsgatan 23
S-164 80, Stockholm
SWEDEN
Email: henrik@levkowetz.com
Vijay Devarapalli
Azaire Networks
4800 Great America Pkwy
Santa Clara, CA 95054
USA
Email: vijay.devarapalli@azairenet.com
Sri Gundavelli
Cisco Systems
170 W.Tasman Drive
San Jose, CA 95134
USA
Email: sgundave@cisco.com
Brian Haley
Hewlett-Packard Company
110 Spitbrook Road
Nashua, NH 03062
USA
Email: brian.haley@hp.com
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