Mobile IPv6 B. Haley
Internet Draft Hewlett-Packard
Document: draft-ietf-mip6-ha-switch-00.txt V. Devarapalli
Expires: December, 2006 Azaire Networks
H. Deng
Hitachi
J. Kempf
DoCoMo USA Labs
June 2006
Mobility Header Home Agent Switch Message
draft-ietf-mip6-ha-switch-00.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Abstract
This document specifies a new Mobility Header message type that can
be used between a home agent and mobile node to signal a mobile node
that it should acquire a new home agent.
Conventions used in this document
Haley, et al Expires - December 2006 [Page 1]
Home Agent Switch Message June 2006
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].
Table of Contents
1. Introduction...................................................2
2. Scenarios......................................................2
2.1 Overloaded.................................................3
2.2 Load Balancing.............................................3
2.3 Maintenance................................................3
2.4 Functional Load Balancing..................................3
2.5 Home Agent Renumbering.....................................3
3. Home Agent Switch Message......................................4
4. Home Agent Operation...........................................6
4.1 Sending Home Agent Switch Messages.........................6
4.2 Retransmissions............................................6
4.3 Mobile Node Errors.........................................7
5. Mobile Node Operation..........................................7
5.1 Receiving Home Agent Switch Messages.......................7
6. Operational Considerations.....................................8
7. Procotol Constants.............................................8
8. IANA Considerations............................................8
9. Security Considerations........................................8
10. References....................................................9
10.1 Normative References......................................9
10.2 Informative references....................................9
Acknowledgments...................................................9
Author's Addresses................................................9
1. Introduction
RFC 3775 [2] contains no provision to allow a home agent to inform a
mobile node that it needs to stop acting as the home agent for the
mobile node. For example, a home agent may wish to handoff some of
its mobile nodes to another home agent because it has become
overloaded or it is going offline.
This protocol describes a signaling message type that can be used to
send a handoff notification between a home agent and mobile node.
2. Scenarios
Here are some example scenarios where a home agent signaling message
would be useful.
Haley, et al Expires - December 2006 [Page 2]
Home Agent Switch Message June 2006
2.1 Overloaded
There are a number of reasons a home agent might be considered
overloaded. One might be that it is at, or near, its limit on the
number of home bindings it is willing to accept. Another is that it
has reached a pre-determined level of system resource usage - memory,
cpu cycles, etc. In either case, it would be desirable for a home
agent to reduce the number of home bindings before a failure occurs.
2.2 Load Balancing
A home agent might know of other home agents on the link that are not
as heavily loaded as itself, learned through some other mechanism
outside the scope of this document. An operator may wish to try and
balance this load so a failure disrupts a smaller percentage of
mobile nodes.
2.3 Maintenance
Most operators do periodic maintenance in order to maintain
reliability. If a home agent is being shutdown for maintenance, it
would be desirable to inform mobile nodes so they do not lose
mobility service.
2.4 Functional Load Balancing
A Mobile IPv6 home agent provides mobile nodes with two basic
services - a rendezvous server where correspondent nodes can find the
current care-of address for the mobile node, and as an overlay router
to tunnel traffic to/from the mobile node at its current care-of
address.
A mobility service provider could have two sets of home agents to
handle the two functions. The rendezvous function could be handled
by a machine specialized for high-speed transaction processing, while
the overlay router function could be handled by a machine with high
data throughput.
A mobile node would start on the rendezvous server home agent and
stay there if it does route optimization. However, if the original
home agent detects that the mobile node is not doing route
optimization, but instead reverse-tunneling traffic, it could
redirect the mobile node to a home agent with better data throughput.
2.5 Home Agent Renumbering
Periodically, a mobility service provider may want to shut-down home
agent services at a set of IPv6 addresses and bring service back up
at a new set of addresses. Note that this may not involve anything
Haley, et al Expires - December 2006 [Page 3]
Home Agent Switch Message June 2006
as complex as IPv6 network renumbering, it may just involve changing
the addresses of the home agents. There are various reasons why a
mobility service provider might want to do this; an example is if the
service provider revokes the account of a user it has reason to
believe might use the old home agent address to disrupt service for
other users. With a signaling message, the service provider could
inform mobile nodes to look for a new home agent.
3. Home Agent Switch Message
The Home Agent Switch message is used by the home agent to signal the
mobile node that it needs to stop acting as the home agent for the
mobile node, and that it should acquire a new home agent. Home Agent
Switch messages are sent as described in Section 4.
The message described below follows the Mobility Header format
specified in Section 6.1 of [2]:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Proto | Header Len | MH Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
. .
. Message Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Haley, et al Expires - December 2006 [Page 4]
Home Agent Switch Message June 2006
The Home Agent Switch 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|# of Addresses | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
. .
. Home Agent Addresses .
. .
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
. .
. Mobility options .
. .
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
# of Addresses
A 16-bit unsigned integer indicating the number of IPv6 home agent
addresses in the message. If set to zero, the mobile node MUST
perform home agent discovery.
Reserved
16-bit field reserved for future use. The value MUST be
initialized to zero by the sender, and MUST be ignored by the
receiver.
Home Agent Addresses
A list of alternate home agent addresses on the home link for the
mobile node. The number of addresses present in the list is
indicated by the "# of Addresses" field in the Home Agent Switch
message.
Mobility options
Haley, et al Expires - December 2006 [Page 5]
Home Agent Switch Message June 2006
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 Home
Agent Switch message.
If no home agent addresses and 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.
4. Home Agent Operation
4.1 Sending Home Agent Switch Messages
When sending a Home Agent Switch 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 If alternative home agent addresses are known, the sending home
agent SHOULD include them in the list of suggested alternate
home agents. The home agent addresses field should be
constructed as described in Section 10.5.1 of [2].
o The "# of addresses" field MUST be filled-in corresponding to
the number of home agent addresses included in the message. If
no addresses are present, the field MUST be set to zero, forcing
the mobile node to perform home agent discovery by some other
means.
The Home Agent Switch message MUST use the home agent to mobile node
IPsec ESP authentication SA for integrity protection.
A home agent SHOULD send a Home Agent Switch message when a known
period of unavailability is pending so the mobile node has sufficient
time to find another suitable home agent.
4.2 Retransmissions
If the home agent does not receive a response from the mobile node (a
Binding Update message to delete its home binding), then it SHOULD
retransmit the message, until a response is received. The initial
value for the retransmission timer is INITIAL-HA-SWITCH-TIMEOUT.
Haley, et al Expires - December 2006 [Page 6]
Home Agent Switch Message June 2006
The retransmissions by the home agent MUST use an exponential back-
off mechanism, in which the timeout period is doubled upon each
retransmission, until either the home agent gets a response from the
mobile node to delete its binding, or the timeout period reaches the
value MAX-HA-SWITCH-TIMEOUT.
4.3 Mobile Node Errors
If a mobile node does not understand how to process a Home Agent
Switch Message, it will send a Binding Error message as described in
Section 5.1.
If a mobile node is unreachable, in other words, it still has a home
binding with the home agent after reaching the timeout period of MAX-
HA-SWITCH-TIMEOUT, the home agent SHOULD NOT make any conclusions
about its status.
In either case, the home agent SHOULD attempt to continue providing
services until the lifetime of the binding expires.
Attempts by the mobile node to extend the binding lifetime with a
Binding Update message SHOULD be rejected, and a Binding
Acknowledgement SHOULD be returned with status value 129
(Administratively prohibited) as specified in Section 6.1.8 of [2].
5. Mobile Node Operation
5.1 Receiving Home Agent Switch Messages
Upon receiving a Home Agent Switch 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] defines. 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.
Upon receipt of a Home Agent Switch message, the mobile node MUST
stop using its current home agent for services and MUST delete its
home binding by sending a Binding Update message as described in [2].
This acts as an acknowledgement of the Home Agent Switch message.
Haley, et al Expires - December 2006 [Page 7]
Home Agent Switch Message June 2006
If the Home Agent Switch message contains a list of alternate home
agent addresses, the mobile node SHOULD select a home agent at random
and establish the necessary IPsec security associations with the new
home agent by whatever means required as part of the mobile node/home
agent bootstrapping protocol for the home agent's mobility service
provider. If no alternate home agent addresses are included in the
list, the mobile node MUST first perform home agent discovery.
6. Operational Considerations
This document does not specify how an operator might use the Home
Agent Switch message in its network. However, it might be the case
that a home agent provides service for many thousands of mobile
nodes. Care should be taken to reduce the signaling overhead
required for handing off many mobile nodes to an alternate home
agent.
7. Procotol Constants
INITIAL-HA-SWITCH-TIMEOUT 5 seconds
MAX-HA-SWITCH-TIMEOUT 20 seconds
8. IANA Considerations
A new Mobility Header type is required for the following new message
described in Section 3:
(TBD) Home Agent Switch message
9. Security Considerations
As with other messages in [2], the Home Agent Switch message MUST use
the home agent to mobile node IPsec ESP authentication SA for
integrity protection.
The Home Agent Switch 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.
Some operators may not want to reveal the list of home agents on the
home link to on-path listeners. In such a case, the Home Agent
Switch message should use the home agent to mobile node IPsec ESP
encryption SA for confidentiality protection.
Haley, et al Expires - December 2006 [Page 8]
Home Agent Switch Message June 2006
10. References
10.1 Normative References
[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.
10.2 Informative references
Acknowledgments
We would like to thank the authors of a number of previous drafts
that contributed content to this document:
o draft-wakikawa-mip6-nemo-haha-spec-00.txt
o draft-deng-mip6-ha-loadbalance-02.txt
o draft-kempf-mip6-ha-alert-00.txt
o draft-haley-mip6-mh-signaling-00.txt
Author's Addresses
Brian Haley
Hewlett-Packard Company
110 Spitbrook Road
Nashua, NH 03062, USA
Email: brian.haley@hp.com
Vijay Devarapalli
Azaire Networks
4800 Great America Pkwy
Santa Clara, CA 95054 USA
Email: vijay.devarapalli@azairenet.com
James Kempf
DoCoMo USA Labs
181 Metro Drive
Suite 300
San Jose, CA 95110 USA
Email: kempf@docomolabs-usa.com
Haley, et al Expires - December 2006 [Page 9]
Home Agent Switch Message June 2006
Hui Deng
Research & Development Center
Hitachi (China), Investment Ltd.
Beijing Fortune Bldg. 1701, 5 Dong San Huan Bei-Lu
Chao Yang District, Beijing 100004, China
Email: hdeng@hitachi.cn
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM 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.
Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Haley, et al Expires - December 2006 [Page 10]
Home Agent Switch Message June 2006
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Haley, et al Expires - December 2006 [Page 11]