draft-ietf-mip6-ha-switch-00.txt   draft-ietf-mip6-ha-switch-01.txt 
Mobile IPv6 B. Haley Mobile IPv6 B. Haley
Internet Draft Hewlett-Packard Internet Draft Hewlett-Packard
Document: draft-ietf-mip6-ha-switch-00.txt V. Devarapalli Document: draft-ietf-mip6-ha-switch-01.txt V. Devarapalli
Expires: December, 2006 Azaire Networks Expires: April, 2006 Azaire Networks
H. Deng H. Deng
Hitachi Hitachi
J. Kempf J. Kempf
DoCoMo USA Labs DoCoMo USA Labs
October 2006
Mobility Header Home Agent Switch Message Mobility Header Home Agent Switch Message
draft-ietf-mip6-ha-switch-00.txt draft-ietf-mip6-ha-switch-01.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware 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 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. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 2, line 20 skipping to change at page 2, line 20
1. Introduction...................................................2 1. Introduction...................................................2
2. Scenarios......................................................2 2. Scenarios......................................................2
2.1 Overloaded.................................................3 2.1 Overloaded.................................................3
2.2 Load Balancing.............................................3 2.2 Load Balancing.............................................3
2.3 Maintenance................................................3 2.3 Maintenance................................................3
2.4 Functional Load Balancing..................................3 2.4 Functional Load Balancing..................................3
2.5 Home Agent Renumbering.....................................3 2.5 Home Agent Renumbering.....................................3
3. Home Agent Switch Message......................................4 3. Home Agent Switch Message......................................4
4. Home Agent Operation...........................................6 4. Home Agent Operation...........................................6
4.1 Sending Home Agent Switch Messages.........................6 4.1 Sending Home Agent Switch Messages.........................6
4.2 Retransmissions............................................6 4.2 Retransmissions............................................7
4.3 Mobile Node Errors.........................................7 4.3 Mobile Node Errors.........................................7
5. Mobile Node Operation..........................................7 5. Mobile Node Operation..........................................7
5.1 Receiving Home Agent Switch Messages.......................7 5.1 Receiving Home Agent Switch Messages.......................7
5.2 Selecting a Home Agent.....................................8
6. Operational Considerations.....................................8 6. Operational Considerations.....................................8
7. Procotol Constants.............................................8 7. Procotol Constants.............................................9
8. IANA Considerations............................................8 8. IANA Considerations............................................9
9. Security Considerations........................................8 9. Security Considerations........................................9
10. References....................................................9 10. References....................................................9
10.1 Normative References......................................9 10.1 Normative References......................................9
10.2 Informative references....................................9 10.2 Informative references...................................10
Acknowledgments...................................................9 Acknowledgments..................................................10
Author's Addresses................................................9 Author's Addresses...............................................10
1. Introduction 1. Introduction
RFC 3775 [2] contains no provision to allow a home agent to inform a 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 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 mobile node. For example, a home agent may wish to handoff some of
its mobile nodes to another home agent because it has become its mobile nodes to another home agent because it has become
overloaded or it is going offline. overloaded or it is going offline.
This protocol describes a signaling message type that can be used to This protocol describes a signaling message type that can be used to
skipping to change at page 3, line 16 skipping to change at page 3, line 16
There are a number of reasons a home agent might be considered 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 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 number of home bindings it is willing to accept. Another is that it
has reached a pre-determined level of system resource usage - memory, has reached a pre-determined level of system resource usage - memory,
cpu cycles, etc. In either case, it would be desirable for a home 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. agent to reduce the number of home bindings before a failure occurs.
2.2 Load Balancing 2.2 Load Balancing
A home agent might know of other home agents on the link that are not A home agent might know of other home agents that are not as heavily
as heavily loaded as itself, learned through some other mechanism loaded as itself, learned through some other mechanism outside the
outside the scope of this document. An operator may wish to try and scope of this document. An operator may wish to try and balance this
balance this load so a failure disrupts a smaller percentage of load so a failure disrupts a smaller percentage of mobile nodes.
mobile nodes.
2.3 Maintenance 2.3 Maintenance
Most operators do periodic maintenance in order to maintain Most operators do periodic maintenance in order to maintain
reliability. If a home agent is being shutdown for maintenance, it reliability. If a home agent is being shutdown for maintenance, it
would be desirable to inform mobile nodes so they do not lose would be desirable to inform mobile nodes so they do not lose
mobility service. mobility service.
2.4 Functional Load Balancing 2.4 Functional Load Balancing
skipping to change at page 4, line 5 skipping to change at page 4, line 4
home agent detects that the mobile node is not doing route home agent detects that the mobile node is not doing route
optimization, but instead reverse-tunneling traffic, it could optimization, but instead reverse-tunneling traffic, it could
redirect the mobile node to a home agent with better data throughput. redirect the mobile node to a home agent with better data throughput.
2.5 Home Agent Renumbering 2.5 Home Agent Renumbering
Periodically, a mobility service provider may want to shut-down home Periodically, a mobility service provider may want to shut-down home
agent services at a set of IPv6 addresses and bring service back up 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 at a new set of addresses. Note that this may not involve anything
as complex as IPv6 network renumbering, it may just involve changing as complex as IPv6 network renumbering, it may just involve changing
the addresses of the home agents. There are various reasons why a the addresses of the home agents. With a signaling message, the
mobility service provider might want to do this; an example is if the service provider could inform mobile nodes to look for a new home
service provider revokes the account of a user it has reason to agent.
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 3. Home Agent Switch Message
The Home Agent Switch message is used by the home agent to signal the 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 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 mobile node, and that it should acquire a new home agent. Home Agent
Switch messages are sent as described in Section 4. Switch messages are sent as described in Section 4.
The message described below follows the Mobility Header format The message described below follows the Mobility Header format
specified in Section 6.1 of [2]: specified in Section 6.1 of [2]:
skipping to change at page 5, line 44 skipping to change at page 5, line 44
perform home agent discovery. perform home agent discovery.
Reserved Reserved
16-bit field reserved for future use. The value MUST be 16-bit field reserved for future use. The value MUST be
initialized to zero by the sender, and MUST be ignored by the initialized to zero by the sender, and MUST be ignored by the
receiver. receiver.
Home Agent Addresses Home Agent Addresses
A list of alternate home agent addresses on the home link for the A list of alternate home agent addresses for the mobile node. The
mobile node. The number of addresses present in the list is number of addresses present in the list is indicated by the "# of
indicated by the "# of Addresses" field in the Home Agent Switch Addresses" field in the Home Agent Switch message.
message.
Mobility options Mobility options
Variable-length field of such length that the complete Mobility Variable-length field of such length that the complete Mobility
Header is an integer multiple of 8 octets long. This field Header is an integer multiple of 8 octets long. This field
contains zero of more TLV-encoded mobility options. The encoding contains zero of more TLV-encoded mobility options. The encoding
and format of defined options MUST follow the format specified in and format of defined options MUST follow the format specified in
Section 6.2 of [2]. The receiver MUST ignore and skip any options Section 6.2 of [2]. The receiver MUST ignore and skip any options
with it does not understand. with it does not understand.
This specification does not define any options valid for the Home This specification does not define any options valid for the Home
skipping to change at page 6, line 30 skipping to change at page 6, line 30
4.1 Sending Home Agent Switch Messages 4.1 Sending Home Agent Switch Messages
When sending a Home Agent Switch message, the sending node constructs When sending a Home Agent Switch message, the sending node constructs
the packet as it would any other Mobility Header, except: the packet as it would any other Mobility Header, except:
o The MH Type field MUST be set to (TBD). o The MH Type field MUST be set to (TBD).
o If alternative home agent addresses are known, the sending home o If alternative home agent addresses are known, the sending home
agent SHOULD include them in the list of suggested alternate agent SHOULD include them in the list of suggested alternate
home agents. The home agent addresses field should be home agents. The home agent addresses field should be
constructed as described in Section 10.5.1 of [2]. constructed as described in Section 10.5.1 of [2], which will
randomize addresses of the same preference in the list.
o The "# of addresses" field MUST be filled-in corresponding to o The "# of addresses" field MUST be filled-in corresponding to
the number of home agent addresses included in the message. If the number of home agent addresses included in the message. If
no addresses are present, the field MUST be set to zero, forcing no addresses are present, the field MUST be set to zero, forcing
the mobile node to perform home agent discovery by some other the mobile node to perform home agent discovery by some other
means. means.
The Home Agent Switch message MUST use the home agent to mobile node The Home Agent Switch message MUST use the home agent to mobile node
IPsec ESP authentication SA for integrity protection. IPsec ESP authentication SA for integrity protection.
A home agent SHOULD send a Home Agent Switch message when a known A home agent SHOULD send a Home Agent Switch message when a known
period of unavailability is pending so the mobile node has sufficient period of unavailability is pending so the mobile node has sufficient
time to find another suitable home agent. time to find another suitable home agent.
The sending node does not need to be the current home agent for the
mobile node, for example as described in [3], but it MUST have a
security association with the mobile node so the message is not
rejected. In this case, the Home Agent Switch message SHOULD only
contain the address of the home agent sending the message in the Home
Agent Addresses field, which implies the mobile node should switch to
using the sender as its new home agent.
4.2 Retransmissions 4.2 Retransmissions
If the home agent does not receive a response from the mobile node (a If the home agent does not receive a response from the mobile node -
Binding Update message to delete its home binding), then it SHOULD either a Binding Update message to delete its home binding if it is
the current home agent, or a Binding Update message to create a home
binding if it is not the current home agent, then it SHOULD
retransmit the message, until a response is received. The initial retransmit the message, until a response is received. The initial
value for the retransmission timer is INITIAL-HA-SWITCH-TIMEOUT. value for the retransmission timer is INITIAL-HA-SWITCH-TIMEOUT.
The retransmissions by the home agent MUST use an exponential back- The retransmissions by the home agent MUST use an exponential back-
off mechanism, in which the timeout period is doubled upon each off mechanism, in which the timeout period is doubled upon each
retransmission, until either the home agent gets a response from the retransmission, until either the home agent gets a response from the
mobile node to delete its binding, or the timeout period reaches the mobile node to delete its binding, or the timeout period reaches the
value MAX-HA-SWITCH-TIMEOUT. value MAX-HA-SWITCH-TIMEOUT.
4.3 Mobile Node Errors 4.3 Mobile Node Errors
skipping to change at page 8, line 4 skipping to change at page 8, line 18
If the packet is dropped due to the above tests, the receiving node 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 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 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 set to 2 (unrecognized MH Type value) if it does not support the
message type. message type.
Upon receipt of a Home Agent Switch message, the mobile node MUST Upon receipt of a Home Agent Switch message, the mobile node MUST
stop using its current home agent for services and MUST delete its stop using its current home agent for services and MUST delete its
home binding by sending a Binding Update message as described in [2]. home binding by sending a Binding Update message as described in [2].
This acts as an acknowledgement of the Home Agent Switch message. This acts as an acknowledgement of the Home Agent Switch message.
Alternately, if the sender of the message is not the current home
agent, sending a Binding Update message to create a home binding will
act as an acknowledgement of the Home Agent Switch message.
If the Home Agent Switch message contains a list of alternate home If the Home Agent Switch message contains a list of alternate home
agent addresses, the mobile node SHOULD select a home agent at random agent addresses, the mobile node SHOULD select a new home agent as
and establish the necessary IPsec security associations with the new described in Section 5.2, and establish the necessary IPsec security
home agent by whatever means required as part of the mobile node/home associations with the new home agent by whatever means required as
agent bootstrapping protocol for the home agent's mobility service part of the mobile node/home agent bootstrapping protocol for the
provider. If no alternate home agent addresses are included in the home agent's mobility service provider. If no alternate home agent
list, the mobile node MUST first perform home agent discovery. addresses are included in the list, the mobile node MUST first
perform home agent discovery.
5.2 Selecting a Home Agent
In most cases, the home agent addresses in the Home Agent Switch
message will be of other home agents on the home link of the mobile
node. In this case, the mobile node SHOULD select a new home agent
from the addresses as they are ordered in the list. If the first
address in the list is unable to provide service, then the subsequent
addresses in the list should be tried in-order.
In the case that the home agent addresses in the Home Agent Switch
message are not all home agents on the home link of the mobile node
(the computed prefix is different), the mobile node SHOULD select one
on the home link first, if available, followed by home agents not on
the home link. Choosing a home agent not on the home link might
require a change of the home address for the mobile node, which could
cause a loss of connectivity for any connections using the current
home address.
6. Operational Considerations 6. Operational Considerations
This document does not specify how an operator might use the Home This document does not specify how an operator might use the Home
Agent Switch message in its network. However, it might be the case Agent Switch message in its network. However, it might be the case
that a home agent provides service for many thousands of mobile that a home agent provides service for many thousands of mobile
nodes. Care should be taken to reduce the signaling overhead nodes. Care should be taken to reduce the signaling overhead
required for handing off many mobile nodes to an alternate home required for handing off many mobile nodes to an alternate home
agent. agent.
skipping to change at page 8, line 45 skipping to change at page 9, line 31
As with other messages in [2], the Home Agent Switch message MUST use As with other messages in [2], the Home Agent Switch message MUST use
the home agent to mobile node IPsec ESP authentication SA for the home agent to mobile node IPsec ESP authentication SA for
integrity protection. integrity protection.
The Home Agent Switch message MAY use the IPsec ESP SA in place for 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 Binding Updates and Acknowledgements as specified in Section 5.1 of
[2], in order to reduce the number of configured security [2], in order to reduce the number of configured security
associations. This also gives the message authenticity protection. associations. This also gives the message authenticity protection.
Some operators may not want to reveal the list of home agents on the Some operators may not want to reveal the list of home agents to on-
home link to on-path listeners. In such a case, the Home Agent path listeners. In such a case, the Home Agent Switch message should
Switch message should use the home agent to mobile node IPsec ESP use the home agent to mobile node IPsec ESP encryption SA for
encryption SA for confidentiality protection. confidentiality protection.
10. References 10. References
10.1 Normative References 10.1 Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
[2] Johnson, D. Perkins, C., and Arkko, J., "Mobility Support in [2] Johnson, D. Perkins, C., and Arkko, J., "Mobility Support in
IPv6", RFC 3775, June, 2004. IPv6", RFC 3775, June, 2004.
10.2 Informative references 10.2 Informative references
[3] Wakikawa, R. (Editor), "Home Agent Reliability Protocol", draft-
ietf-mip6-hareliability-01.txt, October, 2006.
Acknowledgments Acknowledgments
We would like to thank the authors of a number of previous drafts We would like to thank the authors of a number of previous drafts
that contributed content to this document: that contributed content to this document:
o draft-wakikawa-mip6-nemo-haha-spec-00.txt o draft-wakikawa-mip6-nemo-haha-spec-00.txt
o draft-deng-mip6-ha-loadbalance-02.txt o draft-deng-mip6-ha-loadbalance-02.txt
o draft-kempf-mip6-ha-alert-00.txt o draft-kempf-mip6-ha-alert-00.txt
o draft-haley-mip6-mh-signaling-00.txt o draft-haley-mip6-mh-signaling-00.txt
 End of changes. 17 change blocks. 
38 lines changed or deleted 72 lines changed or added

This html diff was produced by rfcdiff 1.33. The latest version is available from http://tools.ietf.org/tools/rfcdiff/