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INTERNET DRAFT James Kempf
Category: Standards Track Pat R. Calhoun
Title: draft-calhoun-mobileip-proactive-fa-00.txt Sun Microsystems, Inc.
Date: January 2000
Foreign Agent Assisted Hand-off
Status of this Memo
This document is an individual contribution for consideration by the
Mobile IP Working Group of the Internet Engineering Task Force.
Comments should be submitted to the diameter@ipass.com mailing list.
Distribution of this memo is unlimited.
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
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The list of current Internet-Drafts can be accessed at:
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Copyright (C) The Internet Society 1999. All Rights Reserved.
Abstract
The Mobile IP WG has been investigating how its protocol can be used
in environments that require fast hand-off, especially important for
real-time applications such as voice and video. Certain link layers,
such as those used in cellular networks, allow for the measurement of
signal strength, which is typically used to determine when a hand-off
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is required. This specification defines extensions to the Mobile IP
protocol, which allows the Foreign Agent to send an unsolicited
message to the Mobile Node, requesting that the Mobile Node register
with a new Foreign Agent.
Table of Contents
1.0 Introduction
1.1 Requirements language
2.0 Operation
2.1 Foreign Agent Considerations
2.2 Mobile Node Considerations
3.0 Mobile Node Hand-Off Request
4.0 Acknowledgements
5.0 IANA Considerations
6.0 Security Considerations
7.0 References
8.0 Authors' Addresses
9.0 Full Copyright Statement
1.0 Introduction
The Mobile IP WG has been investigating how its protocol can be used
in environments that require fast hand-off, especially important for
real-time applications such as voice and video [2]. Certain link
layers, such as those used in cellular networks, allow for the
measurement of signal strength, which is typically used to determine
when a hand-off is required [3].
The Mobile IP protocol [1] currently requires that a Mobile Node
listen for advertisements in order to detect that a hand-off is
required, which can delay the hand-off. Furthermore, it is
questionable whether advertisements are appropriate in a network
whose bandwidth is considered scarce, such as the cellular networks.
This specification defines extensions to the Mobile IP protocol [1],
that allows the Foreign Agent to send an unsolicited message to the
Mobile Node, requesting that the Mobile Node register with a new
Foreign Agent.
1.1 Requirements language
In this document, the key words "MAY", "MUST, "MUST NOT", "optional",
"recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as
described in [4].
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2.0 Operation
This section describes modifications to the Mobile IP protocol used
when the Foreign Agent determines that the Mobile Node could be
better served by another Foreign Agent within it's network.
2.1 Foreign Agent Considerations
When the Foreign Agent detects that a Mobile Node could be better
served through another Foreign Agent, it issues a Binding Update
message [5] to the new Foreign Agent, informing it that it should
inform the Mobile Node to send a Registration Request. The Binding
Update contains the Mobile Node's home address, the security
association it shares with the Mobile Node and it's Home Agent. Note
that the mechanism used by the FA to make the determination that the
Mobile Node should hand-off is outside the scope of this
specification.
+-----+
| oFA |
+-----+
hand-off |
+----+ request | Binding +----+
| MN |<-----------\ | Update | HA |
+----+ | | +----+
| | v ^
Reg| +-----+ |
Req \---------->| nFA |-----------/
+-----+ Reg Req
Figure 1 - Mobile Node hand-off
Upon receipt of the Binding Update, the new Foreign Agent issues a
hand-off request to the Mobile Node, which includes the MN-FA
authentication extension, using the MN-FA security association
information received in the Binding Update. The hand-off request MAY
be retransmitted periodically until the Mobile Node's Registration
Request is received. The new Foreign Agent does the normal
registration message processing, including adding the FA-HA
authentication extension.
During this time, the HA still sends the Mobile Node's packets to the
old Foreign Agent, which are still delivered to the Mobile Node (if
possible), or forwarded to the new Foreign Agent for future delivery
(if necessary).
Upon receipt of the Home Agent's Registration Reply, the new Foreign
Agent forwards the message to the Mobile Node, while issuing the
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Binding Response to the old Foreign Agent. This message MAY be used
by the old Foreign Agent to clean up resources it had allocated to
the Mobile Node.
2.2 Mobile Node Considerations
Upon receipt of the hand-off request from a new Foreign Agent, the
Mobile Node SHOULD still accept data packets from the old Foreign
Agent, until the Registration Reply has been received. The hand-off
request SHOULD include the MN-FA Authentication Extension [1], using
a pre-established security association, or the SA it shared with the
old Foreign Agent.
3.0 Mobile Node Hand-Off Request
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 |S|B|D|M|G|V|rsv| Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Previous Foreign Agent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| New Foreign Agent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Identification +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions ...
+-+-+-+-+-+-+-+-
Type TBD (Hand-off Request)
S Simultaneous bindings MUST be set to zero.
B Broadcast datagrams MUST be set to zero.
D Decapsulation by mobile node MUST be set to zero.
M Minimal encapsulation is set if the Foreign Agent
supports minimal encapsulation.
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G GRE encapsulation is set if the Foreign Agent supports
GRE encapsulation.
V Set to zero.
rsv Reserved bits; sent as zero
Lifetime The maximum lifetime the Foreign Agent will accept in the
Mobile Node's registration request. A value of 0xffff
indicates infinity.
Home Address
The IP address of the mobile node.
Previous Foreign Agent
The IP address of the previous Foreign Agent.
New Foreign Agent
The IP address for the new Foreign Agent.
Identification
A 64-bit field that is set to zero.
Extensions
The fixed portion of the Hand-off Request is followed by
one or more Mobile IP Extensions. The Mobile-Foreign
Authentication Extension SHOULD be included in all Hand-
off Requests.
4.0 Acknowledgements
The authors would like to thank Charles Perkins for his valuable
feedback.
5.0 IANA Considerations
This specification introduces a new value in the Mobile IP type
field. This value MUST NOT conflict with values specified in [1], or
any other Mobile IP extension document.
6.0 Security Considerations
This specification introduces a new Mobile IP message sent by a new
Foreign Agent to request that a Mobile Node register with it. It is
highly recommended that the Hand-off Request message include a
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Mobile-Foreign Authentication Extension to avoid malicious hosts
sending such messages to mobiles.
7.0 References
[1] C. Perkins, Editor. "IP Mobility Support". RFC 2002. October
1996.
[2] T. Hiller et al. "Cdma2000 Wireless Data Requirements for AAA".
draft-hiller-cdma2000-AAA-00.txt (work in progress). October
1999.
[3] U. Black. "2nd Generation Wireless Networks". Prentice-Hall. New
York. 1999.
[4] S. Bradner. "Key words for use in RFCs to Indicate Requirement
Levels". BCP 14. RFC 2119. March 1997.
[5] C. Perkins and D. Johnson. "Route Optimization in Mobile IP".
draft-ietf-mobileip-optim-08.txt (work in progress). Feburary
1999.
8.0 Authors' Addresses
Questions about this memo can be directed to:
James Kempf
Network and Security Research Center, Sun Labs
Sun Microsystems, Inc.
15 Network Circle
Menlo Park, California, 94025
USA
Phone: 1-650-786-7733
Fax: 1-650-786-6445
E-mail: james.kempf@eng.sun.com
Pat R. Calhoun
Network and Security Research Center, Sun Labs
Sun Microsystems, Inc.
15 Network Circle
Menlo Park, California, 94025
USA
Phone: 1-650-786-7733
Fax: 1-650-786-6445
E-mail: pcalhoun@eng.sun.com
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9.0 Full Copyright Statement
Copyright (C) The Internet Society (1999). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English. The limited permissions granted above are perpetual and will
not be revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
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