MIP4 Working Group H. Deng
Internet-Draft China Mobile
Intended status: Standards Track H. Levkowetz
Expires: February 25, 2010 Ericsson Research
V. Devarapalli
WiChorus
S. Gundavelli
Cisco Systems
B. Haley
Hewlett-Packard Company
August 24, 2009
Generic Notification Message for Mobile IPv4
draft-ietf-mip4-generic-notification-message-09.txt
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Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Abstract
This document specifies protocol enhancements that allow Mobile IPv4
entities to send and receive explicit notification messages using a
new Mobile IPv4 message type designed for this purpose.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Notification message - Usage Scenario's . . . . . . . . . . . 7
3.1. Notification message between a Home Agent and a Mobile
Node . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1.1. Mobile Registered using a Foreign Agent Care-of
Address . . . . . . . . . . . . . . . . . . . . . . . 7
3.1.2. Mobile Registered using a Co-located Care-of
Address . . . . . . . . . . . . . . . . . . . . . . . 7
3.2. Notification message between a Foreign Agent and a
Mobile Node . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. Notification message between a Home Agent and a
Foreign Agent . . . . . . . . . . . . . . . . . . . . . . 8
4. Generic Notification Message and Considerations . . . . . . . 9
4.1. Generic Notification Message . . . . . . . . . . . . . . . 9
4.2. Generic Notification Acknowledgment Message . . . . . . . 12
4.3. Mobile Node Consideration . . . . . . . . . . . . . . . . 15
4.3.1. Receiving Generic Notification Messages . . . . . . . 16
4.3.2. Sending Generic Notification Acknowledgement
Message . . . . . . . . . . . . . . . . . . . . . . . 17
4.3.3. Sending Generic Notification Messages . . . . . . . . 17
4.3.4. Receiving Generic Notification Acknowledgement
Messages . . . . . . . . . . . . . . . . . . . . . . . 18
4.4. Foreign Agent Consideration . . . . . . . . . . . . . . . 19
4.4.1. Receiving Generic Notification Message . . . . . . . . 19
4.4.2. Sending Generic Notification Acknowledgement
Messages . . . . . . . . . . . . . . . . . . . . . . . 21
4.4.3. Sending Generic Notification Messages . . . . . . . . 21
4.4.4. Receiving Generic Notification Acknowledgement
Messages . . . . . . . . . . . . . . . . . . . . . . . 22
4.5. Home Agent Consideration . . . . . . . . . . . . . . . . . 23
4.5.1. Sending Generic Notification Messages . . . . . . . . 23
4.5.2. Receiving Generic Notification Acknowledgement
Messages . . . . . . . . . . . . . . . . . . . . . . . 24
4.5.3. Receiving Generic Notification Messages . . . . . . . 24
4.5.4. Sending Generic Notification Acknowledgement
Messages . . . . . . . . . . . . . . . . . . . . . . . 25
5. Usage Example . . . . . . . . . . . . . . . . . . . . . . . . 27
5.1. Generic String Extension . . . . . . . . . . . . . . . . . 27
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6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29
8. Security Considerations . . . . . . . . . . . . . . . . . . . 30
8.1. Replay Protection for GNM, GNAM messages . . . . . . . . . 30
8.1.1. Replay Protection using Timestamps . . . . . . . . . . 30
8.2. Non-authentication Extensions Handling in Foreign Agent . 32
9. Normative References . . . . . . . . . . . . . . . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 34
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1. Introduction
In some situations, there is a need for Mobile IPv4 entities, such as
the home agent(HA), foreign agent(FA) and mobile node(MN) to send and
receive asynchronous notification messages 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 [RFC4917], [RFC3344]. In addition, the following terms are
defined:
Notification Message
A message from a mobility agent to a MN or other mobility agent to
asynchronously notify it about an event that is relevant to the
mobility service it is currently providing.
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, [RFC2119].
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3. Notification message - Usage Scenario's
There are several scenarios where a mobility agent could initiate
notification events. Some of these are described in the following
sections.
3.1. Notification message between a Home Agent and a Mobile Node
3.1.1. Mobile Registered using a Foreign Agent Care-of Address
In this case, the HA cannot directly notify the MN, but must send the
notification via the FA, vice versa.
+----+ notification +----+ notification +----+
| MN |<================>| FA |<=============>| HA |
+----+ +----+ +----+
Figure 1: HA notifies MN or MN notifies HA through FA
3.1.2. Mobile Registered using a Co-located Care-of Address
In this case, the MN has registered with the home agent directly, so
the notification message can go directly to the MN.
The notification mechanism as specified here does not support the
case of Co-located CoA mode with registration through a FA (due to
the 'R' bit being set in the FA's advertisement messages).
+----+ notification +----+
| MN |<===================================>| HA |
+----+ +----+
Figure 2: HA directly notifies MN or MN directly notifies HA
3.2. Notification message between a Foreign Agent and a Mobile Node
There are two cases where a FA may send notification messages to a
MN, 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 FA could be based on RADIUS or Diameter, but this is out of scope
for this document). If the notification is initiated by a FA, the FA
may need to also notify the HA about the event.
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+----+ notification +----+ trigger +--------+
| MN |<================>| FA |<=============| AAA |
+----+ +----+ +--------+
|| notification +----+
================>| HA |
+----+
Figure 3: FA notifies MN
3.3. Notification message between a Home Agent and a Foreign Agent
The HA may also need to send a notification to the FA, but not to the
MN, The FA may also need to send a notification to the HA, as
illustrated below:
+----+ notification +----+
| FA |<=============>| HA |
+----+ +----+
Figure 4: HA notifies FA or FA notifies HA
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4. Generic Notification Message and Considerations
This section describes in detail the Generic Notification Message
(GNM), Generic Notification Acknowledgement Message (GNAM), and some
considerations related to the handling of these messages in the MN,
FA and HA.
The MN and HA MUST maintain the following information, the FA also
need maintain both HA's and MN's direction the below information:
- the IP source address of the Registration Request/Reply
- the IP destination address of the Registration Request/Reply
- the UDP source port of the Registration Request/Reply
- the UDP destination port of the Registration Request/Reply
The sending node always sends the GNM message following the same
procedure for sending Registration Request as in section 3.3 of
[RFC3344] and the receiving node follows the same procedure for
Registration Reply as in section 3.4. of [RFC3344] when sending GNAM.
4.1. Generic Notification Message
A GNM is sent by a mobility agent to inform another mobility agent,
or a MN, of MIP-related information such as vendor specific
extensions[RFC3115] and generic string notification[RFC4917]. These
messages MUST use the same IP and UDP headers as any previous
Registration Request(RRQ) or Reply (RRP) message to the same entity.
This would support NAT traversal and ensure same security association
used for GNM/GNAM and RRQ/RRP. The GNM is defined as follows:
IP Fields:
Source Address Same as the last Registration Reply/Request
message sent.
Destination Address Same as the last Registration Reply/Request
message sent.
UDP Fields:
Source Port Same as the last Registration Reply/Request
message sent.
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Destination Port Same as the last Registration Reply/Request
message sent.
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 | MD |A| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Care-of Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Identification +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions...
+-+-+-+-+-+-+-+-+-+-+-+-+-
Type (TBD)
Subtype
This field describes the particular type of notification which is
carried in the notification message. The following values are
reserved in this document.
0 Reserved
1 Information carried in Vendor specific extensions which is
specified in [RFC3115].
2 Information carried in Generic String extensions which is
specified in [RFC4917].
The value 0 is reserved and SHOULD NOT be used. The value 1
indicates that the actual information is carried in vendor
specific extensions. Other values are reserved for future
extensions.
MD: Message Direction
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This memo defines the semantics of the following MD field value:
0 -- Message sent by the HA to the MN
1 -- Message sent by the HA to the FA
2 -- Message sent by the MN to the HA
3 -- Message sent by the MN to the FA
4 -- Message sent by the FA to the MN
5 -- Message sent by the FA to the HA
A
This bit indicates whether the notification message MUST be
acknowledged by the recipient. if "A" bit has been set during the
message, but the sender doesn't receive any acknowledgement
message, the sender will have to resend the notification message
again.
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 HA.
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 GNM
with GNAM, and for protecting against replay attacks of
notification messages. Here is the same as Sections 5.4 and 5.7
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of [RFC3344]. Timestamps is mandatory and nonces is optional.
Extensions
The fixed portion of the GNM 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].
This document mandates the MN-HA Authentication Extension (AE)
when this message is sent between the MN and the HA, others are
optional. This document also mandate the MN-FA AE when this
message is sent between the MN and the FA, others are optional.
This document mandate the FA-HA AE when this message is sent
between the FA and the HA, others are optional. This could be
judged based on "MD" value.). See Sections 3.6.1.3 and 3.7.2.2 of
[RFC3344] for the rules on the order of these extensions as they
appear in Mobile IPv4 RRQ and RRP messages. The same rules are
applicable to GNM and GNAM.
4.2. Generic Notification Acknowledgment Message
A GNAM is sent by mobility agents or MNs to indicate the successful
receipt of a GNM.
IP Fields:
Source Address Typically copied from the destination
address of the GNM to which the agent is
replying.
Destination Address Copied from the source address of the GNM to
which the agent is replying.
UDP Fields:
Source Port Copied from the destination port of the
corresponding GNM.
Destination Port Copied from the source port of the
corresponding GNM.
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 | MD | code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Care-of Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Identification +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions...
+-+-+-+-+-+-+-+-+-+-+-+-+-
Type (TBD)
Subtype
This field specifies the particular type of notification
acknowledgement message. The following values are reserved in
this document.
0 Reserved
1 Information carried in Vendor specific extensions which is
specified in [RFC3115].
2 Information carried in Generic String extensions which is
specified in [RFC4917].
The value 0 is reserved and SHOULD NOT be used. The value 1
indicates that the actual information is carried in vendor
specific extensions. Other values are reserved for future
extensions.
MD: Message Direction
This memo defines the semantics of the following MD field value:
0 -- Message sent by the HA to the MN
1 -- Message sent by the HA to the FA
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2 -- Message sent by the MN to the HA
3 -- Message sent by the MN to the FA
4 -- Message sent by the FA to the MN
5 -- Message sent by the FA to the HA
code
A value indicating the result of the GNM. See below for a list of
currently defined Code values.
Notification suceessful
0 -- notification accepted
Notification denied by the HA
128 -- reason unspecified
129 -- administratively prohibited
130 -- insufficient resources
131 -- mobile node failed authentication
132 -- foreign agent failed authentication
133 -- notification Identification mismatch
Notification denied by the FA
64 -- reason unspecified
65 -- administratively prohibited
66 -- insufficient resources
67 -- mobile node failed authentication
68 -- home agent failed authentication
69 -- notification Identification mismatch
Notification denied by the mobile node
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192 -- reason unspecified
193 -- administratively prohibited
194 -- insufficient resources
195 -- foreign agent failed authentication
196 -- home agent failed authentication
197 -- notification Identification mismatch
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
if the timestamp of the GNM is valid, the receiver copies the
entire Identification field into the GNAM it returns the GNAM
message to the sender. if the timestamp of the GNM is not valid,
the receiver copies only the low-order 32 bits into the GNAM, and
supplies the high-order 32 bits from its own time of day. Both
GNM and GNAM mandate Timestamps.
Extensions
The fixed portion of the GNAM 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 the rules on the order of
these extensions as they appear in Mobile IPv4 RRQ and RRP
messages. The same rules are applicable to GNM and GNAM.
4.3. Mobile Node Consideration
It is possible that the MN MAY receive a GNM from a FA or HA. Both
in the case of FA-CoA and Co-located CoA, the MN MAY reply with a
GNAM based on the "A" flag in the GNM message.
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4.3.1. Receiving Generic Notification Messages
When the MN is using FA-CoA and receives a Notification message, if
the "MD" value is 0, it means that the notification message came from
the HA. If the "MD" value is 4, the notification came from the FA.
If this notification message came from a FA and the MN accepts the
FA's GNM, it will process the notification extension according to the
specific rules for that extension.
After that, the MN MAY reply GNAM back to the FA. If the "A" flag is
set in the GNM, then the MN MUST send the acknowledgement.
The MN MUST check for the presence of an authorization-enabling
extension, and perform the indicated authentication. Exactly one
authorization-enabling extension MUST be present in the GNM, if this
message came from a FA, MN-FA AE MUST be present, If no MN-FA AE is
found, or if more than one MN-FA AE is found, or if the Authenticator
is invalid, the MN MUST reject the GNM and MAY send a GNAM to the FA
with Code 195, including an Identification field computed in
accordance with the rules specified in Section 7.1.1. The MN MUST do
no further processing with such a notification, though it SHOULD log
the error as a security exception.
The MN MUST check that the Identification field is correct using the
context selected by the SPI within mandatory authentication extension
like MN-FA AE or MN-HA AE. See Section 7.1.1 for a description of
how this is performed. If incorrect, the MN MUST reject the GNM and
MAY send a GNAM to the initiator with Code 197, including an
Identification field computed in accordance with the rules specified
in Section 7.1.1. The MN MUST do no further processing with such a
notification, though it SHOULD log the error as a security exception.
If this notification message came from the HA, relayed by the FA, or
is a Co-located CoA, the MN-HA AE MUST be checked and the MN MUST
check the Authenticator value in the Extension. If no MN-HA AE is
found, or if more than one MN-HA AE is found, or if the Authenticator
is invalid, the MN MUST reject the GNM and MAY send a GNAM to the
initiator with Code 196, including an Identification field computed
in accordance with the rules specified in Section 7.1.1. The MN MUST
do no further processing with such a notification, though it SHOULD
log the error as a security exception. If the MN accepts the HA's
GNM, it will process it according to the specific rules for that
extension. After that, the MN MAY reply with a GNAM with Code 0 back
to the HA based on the "A" flag in the GNM.
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4.3.2. Sending Generic Notification Acknowledgement Message
Both in the case of a Co-located CoA and FA-CoA, the MN MAY reply
with a GNAM based on the "A" flag in the GNM as follows:
If the GNM was initiated from the FA to the MN ("MD" value is set to
4), MN-FA AE MUST be the last extension in order to protect all other
non-authentication extensions as defined in section 3.5.3 of
[RFC3344].
In the case of a FA-CoA, the source address is the MN's address, the
destination address is the FA's address.
The Code field of the GNAM is chosen in accordance with the rules
specified in the section 4.2. When replying to an accepted
notification, a MN SHOULD respond with Code 0.
There are a number of reasons the MN might reject a notification such
as administrative in nature returning a GNAM with a code of 193,
similarly and provides the Code value 192 or 194 for the unspecified
reason and insufficient resources.
If the GNM was initiated from the HA to the MN ("MD" value is set to
0) and in the case of Co-located CoA, MN-HA AE MUST be the last
extension in order to protect all other non-authentication extensions
as defined in section 3.5.2 of [RFC3344]
In the case of a FA-CoA, the source address is the MN's HoA address
and the destination address is the FA's address ("MD" value is set to
2), the ordering of the extension is: any non-authentication
Extensions used only by the HA, followed by the MN-HA AE defined in
section 3.5.2. of [RFC3344], followed by any non-authentication
Extensions used only by the FA, followed by The MN-FA AE defined in
section 3.5.3 of [RFC3344].
4.3.3. Sending Generic Notification Messages
The MN may either send a GNM to notify the FA or HA.
If the message is sent to the FA, the source address is the MN's
address, and the destination address is the FA's address
If the FA is the target of this notification message, then the "MD"
value is set to 3, MN-FA AE MUST be the last extension in order to
protect all other non-authentication extensions. Computing
Authentication Extension Value is the same as section 3.5.1 of
[RFC3344].
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If the FA is working only as a relay agent, the "MD" value is set to
2, and the ordering of the extension is: the notification extension,
followed by any non-authentication extension expected to be used by
HA, followed by MN-HA AE defined in section 3.5.2. of [RFC3344],
followed by any non-authentication Extensions used only by the FA,
followed by The MN-FA AE defined in section 3.5.3 of [RFC3344].
Computing Authentication Extension Value is the same as section 3.5.1
of [RFC3344].
In the case of a Co-located CoA, the MN MAY send a notification
message directly to the HA if it needs to be notified. The "MD"
value is set to 2, and the ordering of the extension is: the
notification extension, followed by any non-authentication extension
expected to be used by HA, followed by MN-HA AE defined in section
3.5.2 of [RFC3344].
The MN chooses the Identification field in accordance with the style
of replay protection it uses with its HA. This is part of the
mobility security association the MN shares with its HA. See Section
7.1.1 for the method by which the MN computes the Identification
field.
4.3.4. Receiving Generic Notification Acknowledgement Messages
In the case of a FA-CoA, if the MN receives this message, and the
"MD" value is set to 0, it means that the GNAM came from HA
If the "MD" value is set to 4, the MN-FA AE MUST be checked, and the
MN MUST check the Authenticator value in the Extension. If no MN-FA
AE is found, or if more than one MN-FA AE is found, or if the
Authenticator is invalid, the MN MUST silently discard the GNAM.
In addition, the low-order 32 bits of the Identification field in the
GNAM MUST be compared to the low-order 32 bits of the Identification
field in the most recent GNM sent to the replying agent. if they do
not match, the GNAM MUST be silently discarded.
If the "MD" value is set to 0, the MN-HA AE MUST be checked, and the
MN MUST check the Authenticator value in the Extension. If no MN-HA
AE is found, or if more than one MN-HA AE is found, or if the
Authenticator is invalid, the MN MUST silently discard the GNAM. If
the MN accepted this message, the MN MAY also process it based on the
notification event.
In the case of a Co-located CoA, if the MN received this message, the
MN-HA AE MUST be checked, and the MN MUST check the Authenticator
value in the Extension. If no MN-HA AE is found, or if more than one
MN-HA AE is found, or if the Authenticator is invalid, the MN MUST
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silently discard the Notification Acknowledgement message.
4.4. Foreign Agent Consideration
The FA may initiate a GNM to the MN or the HA. Additionally, the FA
also relays GNM and GNAM messages between the MN and its HA as long
as there is an active binding for the MN at the FA.
4.4.1. Receiving Generic Notification Message
If the FA receives a GNM, and the "MD" value is set to 0, it means
that the HA is asking the FA to relay the message to the MN. If the
"MD" value is set to 1, it means that the target of the notification
is the FA. If the "MD" value is set to 2, it means that the MN is
asking the FA to relay the message to the HA. If the "MD" value is
set to 3, it means that the notification came from the MN to the FA.
If the "MD" value is set to 0, the FA MAY validate the FA-HA AE if
present. if the FA-HA AE is invalid, all extensions between the HA-MN
AE and the HA-FA AE MUST be removed, FA SHOULD relay the GNM to the
MN's home address as specified in the Home Address field of the GNM,
MN will eventually validate the MN-HA AE to ensure that all
information sent to the MN is integrity protected. If the FA-HA AE
is valid, FA MUST relay the GNM to the MN's home address as specified
in the Home Address field of the GNM. The FA MUST NOT modify any of
the fields beginning with the fixed portion of the GNM through the
MN-HA AE or other authentication extension supplied by the HA as an
authorization-enabling extension for the MN.
Furthermore, the FA MUST process and remove any extensions following
the MN-HA AE. If the FA shares a mobility security association with
the MN, the FA MAY append any of its own non-authentication
extensions which of relevance to the MN. In this case, the FA MUST
append the MN-FA AE after these non-authentication extensions.
If the "MD" value is set to 1, the FA-HA AE MUST be checked, and the
FA MUST check the Authenticator value in the Extension. If no FA-HA
AE is found, or if more than one FA-HA AE is found, or if the
Authenticator is invalid, the FA MUST reject the GNM and MAY send a
GNAM to the HA with Code 68, including an Identification field
computed in accordance with the rules specified in Section 7.1.1.
The FA MUST do no further processing with such a notification, though
it SHOULD log the error as a security exception.
The FA MUST check that the Identification field is correct using the
context selected by the SPI within mandatory FA-HA AE. See Section
7.1.1 for a description of how this is performed. If incorrect, the
FA MUST reject the GNM and MAY send a GNAM to the initiator with Code
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69, including an Identification field computed in accordance with the
rules specified in Section 7.1.1. The FA MUST do no further
processing with such a notification, though it SHOULD log the error
as a security exception.
If FA accepts the HA's GNM, it will process it based on the specific
rules for that extension. The FA MAY then reply with a GNAM with
Code 0 back to the MN based on the "A" flag in the GNM.
In the case of a FA-CoA and if the "MD" value is set to 2, if the FA
received this message, and if the MN-FA AE is presented, the MN-FA AE
MUST be checked, and the FA MUST check the Authenticator value in the
Extension. If no MN-FA AE is found, or if more than one MN-FA AE is
found, or if the Authenticator is invalid, the FA MUST silently
discard the GNM message. If MN-FA is valid, FA MUST relay the GNM to
the HA's address as specified in the Home Agent Address field of the
GNM, HA will eventually validate the MN-HA AE to ensure that all
information sent to the HA is integrity protected. The FA MUST NOT
modify any of the fields beginning with the fixed portion of the GNM
through the MN-HA AE or other authentication extension supplied by
the MN as an authorization-enabling extension for the HA.
Furthermore, the FA MUST process and remove any Extensions following
the MN-HA AE, and MAY append any of its own non-authentication
Extensions of relevance to the HA if applicable, and MUST append the
FA-HA AE, if the FA shares a mobility security association with the
HA.
If the "MD" value is set to 3, the MN-FA AE MUST be checked, and the
FA MUST check the Authenticator value in the Extension which is the
same as the section 3.7.2.1 of RFC 3344. If no MN-FA AE is found, or
if more than one MN-FA AE is found, or if the Authenticator is
invalid, the FA MUST reject the GNM and MAY send a GNAM to the MN
with Code 67, including an Identification field computed in
accordance with the rules specified in Section 7.1.1. The FA MUST do
no further processing with such a notification, though it SHOULD log
the error as a security exception.
The FA MUST check that the Identification field is correct using the
context selected by the SPI within mandatory MN-FA AE. See Section
7.1.1 for a description of how this is performed. If incorrect, the
FA MUST reject the GNM and MAY send a GNAM to the initiator with Code
69, including an Identification field computed in accordance with the
rules specified in Section 7.1.1. The FA MUST do no further
processing with such a notification, though it SHOULD log the error
as a security exception.
If FA accepts the MN's GNM, it will process it based on the specific
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rules for that extension. The FA MAY then reply with a GNAM with
Code 0 back to the MN based on the "A" flag in the GNM.
4.4.2. Sending Generic Notification Acknowledgement Messages
The FA may need to either relay a GNAM message between the MN and the
HA or send one as a response to a GNM messsage that was sent to it.
In both cases, the GNAM message is defined as follows:
The source address is the FA address, the destination address is HA's
or MN's home address.
The Code field of the GNAM is chosen in accordance with the rules
specified in the section 4.2. When replying to an accepted
notification, a FA SHOULD respond with Code 0.
There are a number of reasons the FA might reject a notification such
as administrative in nature returning a GNAM with a code of 65,
similarly and provides the Code value 64 or 66 for the unspecified
reason and insufficient resources.
If the FA is only relaying this message to the HA, the FA MUST NOT
modify any of the fields beginning with the fixed portion of the GNAM
through the including the MN-HA AE or other authentication extension
supplied by the MN as an authorization-enabling extension for the MN.
Furthermore, the foreign agent MUST process and remove any Extensions
following the MN-HA AE. if the FA shares a mobility security
association with the HA, the FA MAY append any of its own non-
authentication extensions which of relevance to the HA, In this case
the FA MUST append the FA-HA AE after these non-authentication
extensions.
If the notification message is from the HA to the FA then the "MD"
value is set to 5 and the ordering of the extension is: any non-
authentication Extensions used only by the FA, followed by The FA-HA
AE defined in section 3.5.4 of [RFC3344].
If the notification message is from the MN to the FA then the "MD"
value is set to 4 and the ordering of the extension is: any non-
authentication Extensions used only by the FA, followed by The MN-FA
AE defined in section 3.5.3 of [RFC3344].
4.4.3. Sending Generic Notification Messages
If the FA is initiating a notification to the MN using the GNM, it
MAY also notify the HA as well.
In the message to the MN, the source address is the FA address, the
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destination address is the MN's address, the "MD" value is set to 4,
and the ordering of the extension is: the notification extension,
followed by any non-authentication Extensions used only by the MN,
followed by The MN-FA AE defined in section 3.5.3 of [RFC3344].
Computing Authentication Extension Value is the same as section 3.5.1
of [RFC3344] except the payload is the notification other than
registration.
In the message to the HA, the source address is the FA's address, the
destination address is the HA's address (the "MD" value is set to 5),
and the ordering of the extension is: notification extension,
followed by any non-authentication Extensions used only by the HA,
followed by The FA-HA AE defined in section 3.5.4 of [RFC3344].
Computing Authentication Extension Value is the same as section 3.5.1
of [RFC3344] except the payload is the notification other than
registration.
4.4.4. Receiving Generic Notification Acknowledgement Messages
In the case of a FA-CoA, if the FA receives this message, and the
"MD" value is set to 3, it means that the notification
acknowledgement message came from the MN, otherwise it came from the
HA.
If the "MD" value is set to 1, the FA-HA AE MUST be checked, and the
FA MUST check the Authenticator value in the Extension. If no FA-HA
AE is found, or if more than one FA-HA AE is found, or if the
Authenticator is invalid, the FA MUST silently discard the
Notification Acknowledgement message. If the FA accepted this
message, the FA MAY also process it based on the notification event.
If the "MD" value is set to 3, if the MN-FA AE is presented, it MUST
be checked, and the FA MUST check the Authenticator value in the
Extension. If no MN-FA AE is found, or if more than one MN-FA AE is
found, or if the Authenticator is invalid, the FA MUST silently
discard the GNAM message. If the FA accepted this message, the FA
MAY also process it based on the notification event.
In the case of a FA-CoA and if the "MD" value is set to 2, if the FA
received this message, and if the MN-FA AE is presented, the MN-FA AE
MUST be checked, and the FA MUST check the Authenticator value in the
Extension. If no MN-FA AE is found, or if more than one MN-FA AE is
found, or if the Authenticator is invalid, the FA MUST silently
discard the GNAM message. If FA accepted the MN's GNAM message, it
MUST relay this message to the HA. The FA MUST NOT modify any of the
fields beginning with the fixed portion of the GNAM message through
the including the MN-HA AE or other authentication extension supplied
by the HA as an authorization-enabling extension for the MN.
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Furthermore, the FA MUST process and remove any Extensions following
the MN-HA AE and MAY append any of its own non-authentication
Extensions of relevance to the HA, if applicable, and MUST append the
FA-HA AE, if the FA shares a mobility security association with the
HA.
4.5. Home Agent Consideration
The HA MAY initiate a GNM message to both the mobile node and FA, and
it also MAY receive a GNAM message from both the FA and MN. The HA
also MAY receive a GNM message from the FA, but only when there is a
binding for a MN. if the HA receives a GNM from a FA and there is no
corresponding MN registration, the HA SHOULD drop the GNM message.
4.5.1. Sending Generic Notification Messages
In the case of a FA-CoA, the HA may either send a GNM to notify the
FA, or have the FA relay the GNM to the MN if the MN needs to be
notified.
If the message is from the HA to the FA, the source address is the
HA's address, and the destination address is the FA's address
If the FA is working only as a relay agent, the "MD" value is set to
0, and the ordering of the extension is: the notification extension,
followed by any non-authentication extension expected to be used by
MN, followed by MN-HA AE defined in section 3.5.2. of [RFC3344],
followed by any non-authentication Extensions used only by the FA,
followed by The FA-HA AE defined in section 3.5.4 of [RFC3344].
Computing Authentication Extension Value is the same as section 3.5.1
of [RFC3344].
If the FA is the target of this notification message, then the "MD"
value is set to 1, and the ordering of the extension is: the
notification extension, followed by any non-authentication Extensions
used only by the FA, followed by The FA-HA AE defined in section
3.5.4 of [RFC3344]. Computing Authentication Extension Value is the
same as section 3.5.1 of [RFC3344].
In the case of a Co-located CoA, the HA MAY send a notification
message directly to the MN if it needs to be notified. The "MD"
value is set to 0, and the ordering of the extension is: the
notification extension, followed by any non-authentication extension
expected to be used by MN, followed by MN-HA AE defined in section
3.5.2. of [RFC3344].
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4.5.2. Receiving Generic Notification Acknowledgement Messages
In the case of a FA-CoA, if the HA receives this message, and the
"MD" value is set to 2, it means that the GNAM message came from MN.
If the "MD" value is set to 5, and the HA accepted this message, the
HA MAY also process it based on the notification event. The FA-HA AE
MUST be checked, and the HA MUST check the Authenticator value in the
Extension. If no FA-HA AE is found, or if more than one FA-HA AE is
found, or if the Authenticator is invalid, the HA MUST silently
discard the GNAM message.
If the "MD" value is set to 2, in the case of a FA-CoA, and if FA-HA
AE is presented, the FA-HA AE MUST be checked, and the HA MUST check
the Authenticator value in the Extension. if more than one FA-HA AE
is found, or if the Authenticator is invalid, the HA MUST silently
discard the GNAM message. Anyway, MN-HA AE MUST be checked, and the
HA MUST check the Authenticator value in the Extension. If no MN-HA
AE is found, or if more than one MN-HA AE is found, or if the
Authenticator is invalid, the HA MUST silently discard the GNAM. If
the HA accepted this message, the HA MAY also process it based on the
notification event.
If the "MD" value is set to 2, in the case of a Co-located CoA, MN-HA
AE MUST be checked, and the HA MUST check the Authenticator value in
the Extension. If no MN-HA AE is found, or if more than one MN-HA AE
is found, or if the Authenticator is invalid, the HA MUST silently
discard the GNAM. If the HA accepted this message, the HA MAY also
process it based on the notification event.
4.5.3. Receiving Generic Notification Messages
The HA MAY receive a GNM message sent from the FA. When the HA
receives this message, if the the "MD" value is set to 5, this
message came from FA. FA-HA AE MUST be checked, and the HA MUST
check the Authenticator value in the Extension. If no FA-HA AE is
found, or if more than one FA-HA AE is found, or if the Authenticator
is invalid, the HA MUST reject the GNM and MAY send a GNAM to the FA
with Code 132, including an Identification field computed in
accordance with the rules specified in Section 7.1.1. The HA MUST do
no further processing with such a notification, though it SHOULD log
the error as a security exception.
The HA MUST check that the Identification field is correct using the
context selected by the SPI within mandatory authentication extension
like MN-HA AE or FA-HA AE. See Section 7.1.1 for a description of
how this is performed. If incorrect, the HA MUST reject the GNM and
MAY send a GNAM to the initiator with Code 133, including an
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Identification field computed in accordance with the rules specified
in Section 7.1.1. The HA MUST do no further processing with such a
notification, though it SHOULD log the error as a security exception.
If HA accepts the FA's GNM message, it will process it based on the
notification extension. Furthermore, the HA MAY reply with a GNAM
message with Code 0 back to the FA based on the "A" flag in the GNM
message.
If the the "MD" value is set to 2, this message come from MN, in the
case of FA-COA, if FA-HA AE is presented, it MUST be checked, and the
HA MUST check the Authenticator value in the Extension. if more than
one FA-HA AE Extension is found, or if the Authenticator is invalid,
the HA MUST reject the GNM and MAY send a GNAM to the FA with Code
132, including an Identification field computed in accordance with
the rules specified in Section 7.1.1. The HA MUST do no further
processing with such a notification, though it SHOULD log the error
as a security exception. And MN-HA AE MUST be checked, and the HA
MUST check the Authenticator value in the Extension. If no MN-HA AE
is found, or if more than one MN-HA AE is found, or if the
Authenticator is invalid, the HA MUST reject the GNM and MAY send a
GNAM to the MN with Code 131, including an Identification field
computed in accordance with the rules specified in Section 7.1.1.
The HA MUST do no further processing with such a notification, though
it SHOULD log the error as a security exception. If HA accepts the
MN's GNM message, it will process it based on the notification
extension. Furthermore, the HA MAY reply with a GNAM message back to
the MN with Code 0 based on the "A" flag in the GNM message.
If the the "MD" value is set to 2, in the case of a Co-located CoA,
the MN-HA AE MUST be checked, and the HA MUST check the Authenticator
value in the Extension. If no MN-HA AE is found, or if more than one
MN-HA AE is found, or if the Authenticator is invalid, the HA MUST
reject the GNM and MAY send a GNAM to the MN with Code 131, including
an Identification field computed in accordance with the rules
specified in Section 7.1.1. The HA MUST do no further processing
with such a notification, though it SHOULD log the error as a
security exception. If HA accepts the MN's GNM message, it will
process it based on the notification extension. Furthermore, the HA
MAY reply with a GNAM message back to the MN with Code 0 based on the
"A" flag in the GNM message.
4.5.4. Sending Generic Notification Acknowledgement Messages
If the GNM message came from the FA only, the HA MAY reply with a
GNAM message to the FA based on the "A" flag in the GNM message. If
the "A" flag is set in the GNM message, then the HA MUST send a GNAM
message. The message is as follows: The source address is HA's
address, the destination address is the FA's address, the "MD" value
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is set to 1. The ordering of the extension is: any non-
authentication Extensions used only by the FA, followed by The
Foreign-Home Authentication extension defined in section 3.5.4 of
[RFC3344].
The Code field of the GNAM is chosen in accordance with the rules
specified in the section 4.2. When replying to an accepted GNM, a MN
SHOULD respond with Code 0.
If the GNM message came from the MN, the HA MAY reply with a GNAM
message to the MN based on the "A" flag in the GNM message. If the
"A" flag is set in the GNM message, then the HA MUST send a GNAM
message. The message is as follows: The source address is HA's
address, the destination address is the FA's address, the "MD" value
is set to 0. The ordering of the extension is: any non-
authentication Extensions used only by the MN, followed by the MN-HA
AE defined in section 3.5.2. of [RFC3344], optionly followed by any
non-authentication Extensions used only by the FA, optionly followed
by The MN-FA AE defined in section 3.5.3 of [RFC3344]
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5. Usage Example
There are several applications that could use this GNM. 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 FA (PDSN) to avoid
over-charging subscribers. Other applications such as HA switch
over, NEMO prefix changes, service or billing related events, load
balancing where the HA wants to move some of the registered mobile
nodes to other HAs, service termination due to end of prepaid time,
and service interruption due to system maintenance.
Here we describe some possible event which could use the generic
string extension [RFC4917] 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. Generic String Extension
In some case, the HA or FA needs to notify the 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 [RFC4917] which is recognized by the MN
easily. An example would be "Maintenance Downtime", "Prepaid
Expiration". These string MUST be strictly defined so they could be
easily understood by all of the network entities, and a suitable GNM
Subtype number would have to be allocated. All such definitions are
left for future specifications.
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6. IANA Considerations
This document describes two new messages, the GNM in section 4.1 and
the GNAM in 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]. The subtype of these two
messages indicate what kind of information is carried and will be
under assigned by IANA namespace.
This document creates a new IANA registry for the Subtype field in
the GNM and GNAM. New values SHOULD be allocated by Standards
Actions or IETF Consensus. This document reserves four values for
the Subtype field
0 Reserved
1 Information carried in Vendor specific extensions
2 Information carried in Generic String Extension
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7. Acknowledgments
The author appreciate the efforts of Ahmad Muhanna in detail
reviewing of this document, lots of text have been contributed by his
suggestions. The author thank the discussion from Kent Leung, Peng
Yang and Peter McCann et al. in the development of this document.
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8. Security Considerations
This specification operates in the security constraints and
requirements of [RFC3344]. It require that when this message is
transmitted between the MN and the HA, MN-HA AE is mandatory, when
this message is transmitted between the MN and the FA, MN-FA AE is
mandatory, when this message is transmitted between the FA and the
HA, FA-HA AE is mandatory. It extends the operations of MN, HA and
FA defined in [RFC3344] to notify each other about some events. The
GNM message defined in the specification could carry information that
modifies the mobility bindings. Therefore the message MUST be
integrity protected. Replay protection MUST also be guaranteed.
RFC 3344 provides replay protection only for registration requests
sent by the MN. There is no mechanism for replay protection for
messages initiated by a FA or a HA. The 64-bit Identification field
specified in this document (Section 4.1 and 4.2) for the GNM message
is used to provide replay protection for the notification messages
initiated by the FA or HA.
8.1. Replay Protection for GNM, GNAM messages
The Identification field is used to let the receiving node verify
that a GNM has been freshly generated by the sending node, not
replayed by an attacker from some previous registration. This
document require that all MNs, FAs and HAs MUST implement timestamp-
based replay protection.
The style of replay protection in effect between any two peer node
among MN, FA and HA. A sending node and its receiving node MUST
agree on which method of replay protection will be used. The
interpretation of the Identification field depends on the method of
replay protection as described in the subsequent subsections.
The low-order 32 bits of the Identification MUST be copied unchanged
from the GNM to the GNMA. The receiver uses those bits (and the
sender's source address) to match GNAM with corresponding replies.
The receiver MUST verify that the low-order 32 bits of any GNAM are
identical to the bits it sent in the GNM.
The Identification in a new GNM MUST NOT be the same as in an
immediately preceding GNM, and SHOULD NOT repeat while the same
security context is being used between the MN and the HA.
8.1.1. Replay Protection using Timestamps
The basic principle of timestamp replay protection is that the node
generating a message inserts the current time of day, and the node
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receiving the message checks that this timestamp is sufficiently
close to its own time of day. Unless specified differently in the
security association between the nodes, a default value of 7 seconds
MAY be used to limit the time difference. This value SHOULD be
greater than 3 seconds. Obviously the two nodes must have adequately
synchronized time-of-day clocks. As with any messages, time
synchronization messages may be protected against tampering by an
authentication mechanism determined by the security context between
the two nodes.
In this document, the timestamps are used, the sender MUST set the
Identification field to a 64-bit value formatted as specified by the
Network Time Protocol[RFC1305]. The low-order 32 bits of the NTP
format represent fractional seconds, and those bits which are not
available from a time source SHOULD be generated from a good source
of randomness. Note, however, that when using timestamps, the 64-bit
Identification used in a GNM message from the sender MUST be greater
than that used in any previous GNM message, as the receiver uses this
field also as a sequence number. Without such a sequence number, it
would be possible for a delayed duplicate of an earlier GNM message
to arrive at the receiver (within the clock synchronization required
by the receiver), and thus be applied out of order, mistakenly
altering the sender's current status.
Upon receipt of a GNM message with an authorization-enabling
extension, the receiver MUST check the Identification field for
validity. In order to be valid, the timestamp contained in the
Identification field MUST be close enough to the receiver's time of
day clock and the timestamp MUST be greater than all previously
accepted timestamps for the requesting sender. Time tolerances and
resynchronization details are specific to a particular mobility
security association.
If the timestamp is valid, the receiver copies the entire
Identification field into the GNAM it returns the GNAM message to the
sender. If the timestamp is not valid, the receiver copies only the
low-order 32 bits into the GNAM, and supplies the high-order 32 bits
from its own time of day. In this latter case, the receiver MUST
reject the registration by returning Code 69/133/197 (identification
mismatch) in the GNAM message.
Furthermore, the receiver MUST verify that the low-order 32 bits of
the Identification in the GNAM are identical to those in the rejected
GNM attempt, before using the high-order bits for clock
resynchronization.
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8.2. Non-authentication Extensions Handling in Foreign Agent
When the FA is relaying the GNM message between the MN and the HA,
and if the FA does not share a mobility security association with the
MN or HA, all non-authentication extensions between MN and FA, or FA
and HA are not protected.
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9. Normative References
[RFC1305] Mills, D., "Network Time Protocol (Version 3)
Specification, Implementation", RFC 1305, March 1992.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3115] Dommety, G. and K. Leung, "Mobile IP Vendor/
Organization-Specific Extensions", RFC 3115, April 2001.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
[RFC4917] Sastry, V., Leung, K., and A. Patel, "Mobile IPv4 Message
String Extension", RFC 4917, June 2007.
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Authors' Addresses
Hui Deng
China Mobile
53A,Xibianmennei Ave.,
Xuanwu District,
Beijing 100053
China
Email: denghui02@gmail.com
Henrik Levkowetz
Ericsson Research
Torshamsgatan 23
S-164 80, Stockholm
SWEDEN
Email: henrik@levkowetz.com
Vijay Devarapalli
WiChorus
3590 North First St
San Jose, CA
USA
Email: dvijay@gmail.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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