MIP6 Working Group Brian Haley
Internet Draft Hewlett-Packard
Intended status: Standards Track Sri Gundavelli
Expires: January, 2008 Cisco Systems
October 2007
Generic Notification Message for Mobile IPv6
draft-ietf-mip6-generic-notification-message-00.txt
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Abstract
This document specifies a new Mobility Header message type that
allows Mobile IPv6 entities to send and receive generic notification
messages.
Conventions used in this document
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 [1].
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Table of Contents
1. Introduction...................................................2
2. Generic Notification Messages..................................2
2.1 Generic Notification Request Message.......................3
2.2 Generic Notification Acknowledgement Message...............4
3. Sending Generic Notification Messages..........................5
3.1 Sending Generic Notification Request Messages..............5
3.2 Sending Generic Notification Acknowledgement Messages......6
4. Receiving Generic Notification Messages........................6
4.1 Receiving Generic Notification Request Messages............6
4.1.1 Mobile Node Operation....................................7
4.1.2 Home Agent Operation.....................................7
4.1.3 Retransmissions..........................................7
5. Protocol Constants.............................................8
6. IANA Considerations............................................8
7. Security Considerations........................................8
8. References.....................................................8
8.1 Normative Reference........................................8
8.2 Informative references.....................................9
Acknowledgments...................................................9
Author's Addresses................................................9
1. Introduction
RFC 3775 [2] contains no provision for Mobile IPv6 entities, such as
a home agent or mobile node, to send and receive asynchronous
notification messages during a mobility session.
This document describes a generic notification message protocol that
can be used by Mobile IPv6 entities for sending and receiving simple
notification events.
The document does not define any specific events, or the
corresponding actions that the receiver is required to do upon
receiving an event.
2. Generic Notification Messages
The messages described below follow the Mobility Header format
specified in Section 6.1 of [2]:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Proto | Header Len | MH Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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| |
. .
. Message Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2.1 Generic Notification Request Message
The Generic Notification Request message is used by the home agent to
notify the mobile node, or vice-versa, that there is an event that
requires attention. This packet is sent as described in Section 3.
The Generic Notification Request message uses the MH Type value
(TBD). When this value is indicated in the MH Type field, the format
of the Message Data field in the Mobility Header is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| Reserved | Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Acknowledge (A)
The Acknowledge (A) bit is set by the sender to request a Generic
Notification Acknowledgement (Section 3.1) be returned upon receipt
of a Generic Notification Request.
Reserved
These fields are unused. They MUST be initialized to zero by the
sender, and MUST be ignored by the receiver.
Sequence #
An 8-bit unsigned integer used by the receiving node to sequence
Generic Notification Requests and by the sending node to match a
returned Generic Notification Acknowledgement with this Generic
Notification Request.
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Mobility options
Variable-length field of such length that the complete Mobility
Header is an integer multiple of 8 octets long. This field
contains zero of more TLV-encoded mobility options. The encoding
and format of defined options MUST follow the format specified in
Section 6.2 of [2]. The receiver MUST ignore and skip any options
with it does not understand.
This specification does not define any options valid for the
Generic Notification Request message.
If no options are present in this message, no padding is necessary
and the Header Len field in the Mobility Header will be set to 0.
2.2 Generic Notification Acknowledgement Message
The Generic Notification Acknowledgement message is used by the home
agent to notify the mobile node, or vice-versa, that there is an
event that requires attention. This packet is sent as described in
Section 3.
The Generic Notification Acknowledgement message uses the MH Type
value (TBD). When this value is indicated in the MH Type field, the
format of the Message Data field in the Mobility Header is as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status | Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Status
8-bit unsigned integer indicating the disposition of the Signaling
Request. Values of the Status field less than 128 indicate that
the Signaling Request was accepted by the receiving node. Values
greater than or equal to 128 indicate that the Signaling Request
was rejected by the receiving node. The following Status values
are currently defined:
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0 Notification Request accepted
128 Reason unspecified
129 Administratively prohibited
130 Insufficient resources
131 Unsupported mobility option
132 Not home agent for this mobile node
Sequence #
An 8-bit unsigned integer used by the receiving node to sequence
Generic Notification Requests and by the sending node to match a
returned Generic Notification Acknowledgement with this Generic
Notification Request. The sequence number in the Generic
Notification Acknowledgement is copied from the sequence number
field in the Generic Notification Request.
Mobility options
Variable-length field of such length that the complete Mobility
Header is an integer multiple of 8 octets long. This field
contains zero of more TLV-encoded mobility options. The encoding
and format of defined options MUST follow the format specified in
Section 6.2 of [2]. The receiver MUST ignore and skip any options
with it does not understand.
This specification does not define any options valid for the
Generic Notification Acknowledgement message.
If no options are present in this message, no padding is necessary
and the Header Len field in the Mobility Header will be set to 0.
3. Sending Generic Notification Messages
3.1 Sending Generic Notification Request Messages
When sending a Generic Notification message, the sending node
constructs the packet as it would any other Mobility Header, except:
o The MH Type field MUST be set to (TBD).
o The Acknowledge (A) bit MAY be set to indicate the receiver must
send a Generic Notification Acknowledgement.
The Generic Notification Request message MUST use the home agent to
mobile node IPsec ESP authentication SA for integrity protection.
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3.2 Sending Generic Notification Acknowledgement Messages
A Generic Notification Acknowledgement message should be sent to
indicate receipt of a Generic Notification Request as follows:
o If the Generic Notification Request was discarded because it
does not meet the requirements as specified in [2] described in
Section 4, a Generic Notification Acknowledgement MUST NOT be
sent. Otherwise, the treatment depends on the below rule.
o If the Acknowledgement (A) bit is set in the Generic
Notification Request, a Generic Notification Acknowledgement
MUST be sent. Otherwise, the treatment depends on the below
rule.
o If the Generic Notification Request was discarded for any other
reason, a Generic Notification Acknowledgement SHOULD be sent.
If the Source Address field of the IPv6 header that carried the
Generic Notification Request does not contain a unicast address, the
Generic Notification Acknowledgement MUST NOT be sent, and the
Generic Notification Request packet MUST be silently discarded.
Otherwise, the acknowledgement MUST be sent to the Source Address.
4. Receiving Generic Notification Messages
Upon receiving a Generic Notification message, the Mobility Header
MUST be verified as specified in [2], specifically:
o The Checksum, MH type, Payload Proto and Header Len fields MUST
meet the requirements of Section 9.2 of [2].
o The packet MUST be covered by the home agent to mobile node
IPsec ESP authentication SA for integrity protection.
If the packet is dropped due to the above tests, the receiving node
MUST follow the processing rules as Section 9.2 of [2]. For example,
it MUST send a Binding Error message with the Status field set to 2
(unrecognized MH Type value) if it does not support the message type.
Subsequent checks depend on the current mode of operation of the
node.
4.1 Receiving Generic Notification Request Messages
If the Generic Notification Request message is valid according to the
tests in Section 4, then it is processed further as follows:
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o If the receiving node does not allow Generic Notification
Request messages, it MUST reject the request and SHOULD return a
Generic Notification Acknowledgement to the sender in which the
Status field is set to 129 (administratively prohibited).
o If the receiving node does not support the type of Mobility
Option in the Generic Notification Request message, it MUST
reject the request and SHOULD return a Generic Notification
Acknowledgement to the sender in which the Status field is set
to 131 (unsupported mobility option).
Subsequent checks depend on the current mode of operation of the
node.
4.1.1 Mobile Node Operation
If the mobile node rejects the Generic Notification Request message
for any other reason than specified in Section 4, it SHOULD return a
Generic Notification Acknowledgement to the home agent in which the
Status field is set to 128 (reason unspecified).
4.1.2 Home Agent Operation
If the receiving node is a home agent, it MUST perform these
additional checks:
o If the home agent has no entry marked as a home registration in
its Binding Cache for this mobile node, then this node MUST
reject the request and SHOULD return a Generic Notification
Acknowledgement to the mobile node in which the Status field is
set to 132 (not home agent for this mobile node).
o If the home agent cannot process the Generic Notification
Request message because it is over-utilized, it MUST reject the
request and SHOULD return a Generic Notification Acknowledgement
to the mobile node in which the Status field is set to 130
(insufficient resources).
If the home agent rejects the Generic Notification Request message
for any other reason, it SHOULD return a Generic Notification
Acknowledgement to the mobile node in which the Status field is set
to 128 (reason unspecified).
4.1.3 Retransmissions
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If the sender has set the Acknowledge (A) bit in the Generic
Notification Request, but does not receive a Generic Notification
Acknowledgement, then it MAY retransmit the message, until a response
is received. The initial value for the retransmission timer is
INITIAL_MH_NOTIFICATION_TIMEOUT. The retransmissions by the sender
MUST use an exponential back-off mechanism, in which the timeout
period is doubled upon each retransmission, until either the sender
gets a response from the target node, or the timeout period reaches
the value MAX_MH_NOTIFICATION_TIMEOUT.
5. Protocol Constants
INITIAL_MH_NOTIFICATION_TIMEOUT 5 seconds
MAX_MH_NOTIFICATION_TIMEOUT 20 seconds
6. IANA Considerations
A new Mobility Header type is required for the following new message
described in Section 2:
(TBD) Generic Notification Request Message
(TBD) Generic Notification Acknowledgement Message
7. Security Considerations
As with other messages in [2], the Generic Notification message MUST
use the home agent to mobile node ESP encryption SA for
confidentiality protection, and MUST use the home agent to mobile
node ESP authentication SA for integrity protection.
The Generic Notification message MAY use the IPsec ESP SA in place
for Binding Updates and Acknowledgements as specified in Section 5.1
of [2], in order to reduce the number of configured security
associations. This also gives the message authenticity protection.
8. References
8.1 Normative Reference
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Johnson, D. Perkins, C., and Arkko, J., "Mobility Support in
IPv6", RFC 3775, June, 2004
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8.2 Informative references
Acknowledgments
Thanks to Hui Deng, James Kempf and Vijay Devarapalli for their
initial review of the draft.
Author's Addresses
Brian Haley
Hewlett-Packard Company
110 Spitbrook Road
Nashua, NH 03062, USA
Email: brian.haley@hp.com
Sri Gundavelli
Cisco Systems
170 W.Tasman Drive
San Jose, CA 95134, USA
Email: sgundave@cisco.com
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