draft-ietf-mip6-ha-switch-06.txt   rfc5142.txt 
Mobile IPv6 B. Haley Network Working Group B. Haley
Internet Draft Hewlett-Packard Request for Comments: 5142 Hewlett-Packard
Document: draft-ietf-mip6-ha-switch-06.txt V. Devarapalli Category: Standards Track V. Devarapalli
Intended status: Standards Track Azaire Networks Azaire Networks
Expires: June 4, 2008 H. Deng H. Deng
China Mobile China Mobile
J. Kempf J. Kempf
DoCoMo USA Labs DoCoMo USA Labs
December 4, 2007 January 2008
Mobility Header Home Agent Switch Message Mobility Header Home Agent Switch Message
draft-ietf-mip6-ha-switch-06.txt
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Abstract Abstract
This document specifies a new Mobility Header message type that can 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 be used between a home agent and mobile node to signal to a mobile
that it should acquire a new home agent. node that it should acquire a new home agent.
Table of Contents Table of Contents
1. Introduction...................................................2 1. Introduction ....................................................2
2. Terminology....................................................3 2. Terminology .....................................................3
3. Scenarios......................................................3 3. Scenarios .......................................................3
3.1 Overloaded.................................................3 3.1. Overloaded .................................................3
3.2 Load Balancing.............................................3 3.2. Load Balancing .............................................3
3.3 Maintenance................................................3 3.3. Maintenance ................................................3
3.4 Functional Load Balancing..................................3 3.4. Functional Load Balancing ..................................3
3.5 Home Agent Renumbering.....................................4 3.5. Home Agent Renumbering .....................................4
4. Home Agent Switch Message......................................4 4. Home Agent Switch Message .......................................4
5. Home Agent Operation...........................................6 5. Home Agent Operation ............................................6
5.1 Sending Home Agent Switch Messages.........................6 5.1. Sending Home Agent Switch Messages .........................6
5.2 Retransmissions............................................7 5.2. Retransmissions ............................................7
5.3 Mobile Node Errors.........................................7 5.3. Mobile Node Errors .........................................7
6. Mobile Node Operation..........................................8 6. Mobile Node Operation ...........................................8
6.1 Receiving Home Agent Switch Messages.......................8 6.1. Receiving Home Agent Switch Messages .......................8
6.2 Selecting a Home Agent.....................................8 6.2. Selecting a Home Agent .....................................9
7. Operational Considerations.....................................9 7. Operational Considerations ......................................9
8. Procotol Constants............................................10 8. Protocol Constants .............................................10
9. IANA Considerations...........................................10 9. IANA Considerations ............................................10
10. Security Considerations......................................10 10. Security Considerations .......................................10
11. References...................................................10 11. References ....................................................11
11.1 Normative References.....................................10 11.1. Normative References .....................................11
11.2 Informative references...................................10 11.2. Informative References ...................................11
Acknowledgments..................................................11 Acknowledgments ...................................................11
Author's Addresses...............................................11
1. Introduction 1. Introduction
RFC 3775 [RFC3775] contains no provision to allow a home agent to RFC 3775 [RFC3775] contains no provision to allow a home agent to
inform a mobile node that it needs to stop acting as the home agent 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 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 some of 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, called the Home Agent This protocol describes a signaling message, called the Home Agent
skipping to change at page 3, line 7 skipping to change at page 3, line 7
The Home Agent Switch message does not attempt to solve all general The Home Agent Switch message does not attempt to solve all general
problems related to changing the home agent of a mobile node. In problems related to changing the home agent of a mobile node. In
particular, this protocol does not attempt to solve: particular, this protocol does not attempt to solve:
o The case where the Home Address of a mobile node must change in o The case where the Home Address of a mobile node must change in
order to switch to a new home agent. This operation should be order to switch to a new home agent. This operation should be
avoided using this message. avoided using this message.
o Determining when a home agent should actively move mobile nodes o Determining when a home agent should actively move mobile nodes
to another home agent. This decision should be made by a to another home agent. This decision should be made by a
backend protocol, for example, as described in [draft-mip6- backend protocol, for example, as described in [hareliability].
hareliability].
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
3. Scenarios 3. Scenarios
Here are some example scenarios where a home agent signaling message Here are some example scenarios where a home agent signaling message
would be useful. would be useful.
3.1 Overloaded 3.1. Overloaded
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 --
cpu cycles, etc. In either case, it would be desirable for a home memory, cpu cycles, etc. In either case, it would be desirable for a
agent to reduce the number of home bindings before a failure occurs. home agent to reduce the number of home bindings before a failure
occurs.
3.2 Load Balancing 3.2. Load Balancing
A home agent might know of other home agents that are not as heavily A home agent might know of other home agents that are not as heavily
loaded as itself, learned through some other mechanism outside the loaded as itself, learned through some other mechanism outside the
scope of this document. An operator may wish to try and balance this scope of this document. An operator may wish to try and balance this
load so a failure disrupts a smaller percentage of mobile nodes. load so that a failure would disrupt a smaller percentage of mobile
nodes.
3.3 Maintenance 3.3. 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.
3.4 Functional Load Balancing 3.4. Functional Load Balancing
A Mobile IPv6 home agent provides mobile nodes with two basic A Mobile IPv6 home agent provides mobile nodes with two basic
services - a rendezvous server where correspondent nodes can find the services. It acts as a rendezvous server where correspondent nodes
current care-of address for the mobile node, and as an overlay router can find the current care-of address for the mobile node, and as an
to tunnel traffic to/from the mobile node at its current care-of overlay router to tunnel traffic to/from the mobile node at its
address. current care-of address.
A mobility service provider could have two sets of home agents to A mobility service provider could have two sets of home agents to
handle the two functions. The rendezvous function could be handled handle the two functions. The rendezvous function could be handled
by a machine specialized for high-speed transaction processing, while by a machine specialized for high-speed transaction processing, while
the overlay router function could be handled by a machine with high the overlay router function could be handled by a machine with high
data throughput. data throughput.
A mobile node would start on the rendezvous server home agent and A mobile node would start on the rendezvous server home agent and
stay there if it does route optimization. However, if the original stay there if it does route optimization. However, if the original
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.
3.5 Home Agent Renumbering 3.5. 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 [RFC4192], it may just involve as complex as IPv6 network renumbering [RFC4192]; it may just involve
changing the addresses of the home agents. With a signaling message, changing the addresses of the home agents. With a signaling message,
the service provider could inform mobile nodes to look for a new home the service provider could inform mobile nodes to look for a new home
agent. agent.
4. Home Agent Switch Message 4. 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 to
mobile node that it needs to stop acting as the home agent for the the mobile node that it needs to stop acting as the home agent for
mobile node, and that it should acquire a new home agent. Home Agent the mobile node, and that it should acquire a new home agent. Home
Switch messages are sent as described in Section 5. Agent Switch messages are sent as described in Section 5.
The message described below follows the Mobility Header format The message described below follows the Mobility Header format
specified in Section 6.1 of [RFC3775]: specified in Section 6.1 of [RFC3775]:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Proto | Header Len | MH Type | Reserved | | Payload Proto | Header Len | MH Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | | | Checksum | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
. . . .
. Message Data . . Message Data .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Home Agent Switch Message uses the MH Type value (TBD). When The Home Agent Switch Message uses the MH Type value (12). When this
this value is indicated in the MH Type field, the format of the value is indicated in the MH Type field, the format of the Message
Message Data field in the Mobility Header is as follows: Data field in the Mobility Header is as follows:
0 1 2 3 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 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 | |# of Addresses | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Home Agent Addresses . . Home Agent Addresses .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Mobility options . . Mobility Options .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
# of Addresses # of Addresses
An 8-bit unsigned integer indicating the number of IPv6 home agent An 8-bit unsigned integer indicating the number of IPv6 home agent
addresses in the message. If set to zero, the mobile node MUST addresses in the message. If set to zero, the mobile node MUST
perform home agent discovery. perform home agent discovery.
Reserved Reserved
8-bit field reserved for future use. The value MUST be initialized An 8-bit field reserved for future use. The value MUST be
to zero by the sender, and MUST be ignored by the receiver. initialized to zero by the sender, and MUST be ignored by the
receiver.
Home Agent Addresses Home Agent Addresses
A list of alternate home agent addresses for the mobile node. The A list of alternate home agent addresses for the mobile node. The
number of addresses present in the list is indicated by the "# of number of addresses present in the list is indicated by the "# of
Addresses" field in the Home Agent Switch message. Addresses" field in the Home Agent Switch message.
Mobility options Mobility Options
Variable-length field of such length that the complete Mobility A 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 or more TLV-encoded mobility options. The encoding contains zero or 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 [RFC3775]. The receiver MUST ignore and skip any Section 6.2 of [RFC3775]. The receiver MUST ignore and skip any
options which it does not understand. options that it does not understand.
The Binding Refresh Advice mobility option defined in Section 6.2.4 The Binding Refresh Advice mobility option defined in Section
of [RFC3775] is valid for the Home Agent Switch message. 6.2.4 of [RFC3775] is valid for the Home Agent Switch message.
If no home agent addresses and no options are present in this If no home agent addresses and no options are present in this
message, no padding is necessary and the Header Len field in the message, no padding is necessary and the Header Len field in the
Mobility Header will be set to 0. Mobility Header will be set to zero.
5. Home Agent Operation 5. Home Agent Operation
5.1 Sending Home Agent Switch Messages 5.1. 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 (12).
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 [RFC3775], which constructed as described in Section 10.5.1 of [RFC3775], which
will randomize addresses of the same preference in the list. 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,
the mobile node to perform home agent discovery by some other forcing the mobile node to perform home agent discovery by some
means. other means.
o If the home agent is able to continue offering services to the o If the home agent is able to continue offering services to the
mobile node for some period of time, it MAY include a Binding mobile node for some period of time, it MAY include a Binding
Refresh Advice mobility option indicating the time (in units of Refresh Advice mobility option indicating the time (in units of
4 seconds) until the binding will be deleted. 4 seconds) until the binding will be deleted.
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 (Encapsulating Security Payload) authentication SA
(Security Association) 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 The sending node does not need to be the current home agent for the
mobile node, for example as described in [draft-mip6-hareliability], mobile node, for example as described in [hareliability], but it MUST
but it MUST have a security association with the mobile node so the have a security association with the mobile node so the message is
message is not rejected. In this case, the Home Agent Switch message not rejected. In this case, the Home Agent Switch message SHOULD
SHOULD only contain the address of the home agent sending the message only contain the address of the home agent sending the message in the
in the Home Agent Addresses field, which implies the mobile node Home Agent Addresses field, which implies that the mobile node should
should switch to using the sender as its new home agent. switch to using the sender as its new home agent.
5.2 Retransmissions 5.2. Retransmissions
If the home agent does not receive a response from the mobile node - If the home agent does not receive a response from the mobile node --
either a Binding Update message to delete its home binding if it is 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 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 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. The home agent MAY continue to send value MAX-HA-SWITCH-TIMEOUT. The home agent MAY continue to send
these messages at this slower rate indefinitely. these messages at this slower rate indefinitely.
If the home agent included a Binding Refresh Advice mobility option, If the home agent included a Binding Refresh Advice mobility option,
then it SHOULD delay any retransmissions until at least one half of then it SHOULD delay any retransmissions until at least one half of
the time period has expired, or INITIAL-HA-SWITCH-TIMEOUT, whichever the time period has expired, or INITIAL-HA-SWITCH-TIMEOUT, whichever
value is less. value is less.
5.3 Mobile Node Errors 5.3. Mobile Node Errors
If a mobile node does not understand how to process a Home Agent 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 Switch message, it will send a Binding Error message as described in
Section 6.1. Section 6.1.
If a mobile node is unreachable, in other words, it still has a home 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- binding with the home agent after reaching the timeout period of MAX-
HA-SWITCH-TIMEOUT, the home agent SHOULD NOT make any conclusions HA-SWITCH-TIMEOUT, the home agent SHOULD NOT make any conclusions
about its status. about its status.
In either case, the home agent SHOULD attempt to continue providing In either case, the home agent SHOULD attempt to continue providing
services until the lifetime of the binding expires. services until the lifetime of the binding expires.
Attempts by the mobile node to extend the binding lifetime with a Attempts by the mobile node to extend the binding lifetime with a
Binding Update message SHOULD be rejected, and a Binding Binding Update message SHOULD be rejected, and a Binding
Acknowledgement SHOULD be returned with status value 129 Acknowledgement SHOULD be returned with status value 129
(Administratively prohibited) as specified in Section 6.1.8 of (Administratively prohibited) as specified in Section 6.1.8 of
[RFC3775]. [RFC3775].
6. Mobile Node Operation 6. Mobile Node Operation
6.1 Receiving Home Agent Switch Messages 6.1. Receiving Home Agent Switch Messages
Upon receiving a Home Agent Switch message, the Mobility Header MUST Upon receiving a Home Agent Switch message, the Mobility Header MUST
be verified as specified in [RFC3775], specifically: be verified as specified in [RFC3775], specifically:
o The Checksum, MH type, Payload Proto and Header Len fields o The Checksum, MH type, Payload Proto, and Header Len fields
MUST meet the requirements of Section 9.2 of [RFC3775]. MUST meet the requirements of Section 9.2 of [RFC3775].
o The packet MUST be covered by the home agent to mobile node o The packet MUST be covered by the home agent to mobile node
IPsec ESP authentication SA for integrity protection. IPsec ESP authentication SA for integrity protection.
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 [RFC3775] defines. MUST follow the processing rules as Section 9.2 of [RFC3775] defines.
For example, it MUST send a Binding Error message with the Status 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 field set to 2 (unrecognized MH Type value) if it does not support
the message type. the message type.
skipping to change at page 8, line 47 skipping to change at page 9, line 5
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 new home agent as agent addresses, the mobile node SHOULD select a new home agent as
described in Section 6.2, and establish the necessary IPsec security described in Section 6.2, and establish the necessary IPsec security
associations with the new home agent by whatever means required as associations with the new home agent by whatever means required as
part of the mobile node/home agent bootstrapping protocol for the part of the mobile node/home agent bootstrapping protocol for the
home agent's mobility service provider. If no alternate home agent home agent's mobility service provider. If no alternate home agent
addresses are included in the list, the mobile node MUST first addresses are included in the list, the mobile node MUST first
perform home agent discovery. perform home agent discovery.
6.2 Selecting a Home Agent 6.2. Selecting a Home Agent
In most cases, the home agent addresses in the Home Agent Switch 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 message will be of other home agents on the home link of the mobile
node (the computed prefix is the same). In this case, the mobile node (the computed prefix is the same). In this case, the mobile
node SHOULD select a new home agent from the addresses as they are 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 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 provide service, then the subsequent addresses in the list should be
tried in-order. tried in-order.
In the case that the home agent addresses in the Home Agent Switch 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 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 (the computed prefix is different), the mobile node SHOULD select one
its home network prefix first, if available, followed by home agents with its home network prefix first, if available, followed by home
with other prefixes. Choosing a home agent with a different prefix agents with other prefixes. Choosing a home agent with a different
might require a change of the home address for the mobile node, which prefix might require a change of the home address for the mobile
could cause a loss of connectivity for any connections using the node, which could cause a loss of connectivity for any connections
current home address. using the current home address.
7. Operational Considerations 7. 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, the following Agent Switch message in its network. However, the following
requirements are placed on the usage: requirements are placed on its usage:
o The use of this message needs to take into account possible o The use of this message needs to take into account possible
signaling overhead, congestion, load from the mechanism signaling overhead, congestion, load from the mechanism itself,
itself, and the resulting registration to another home agent. and the resulting registration to another home agent. A home
A home agent may provide service for thousands, if not agent may provide service for thousands, if not millions, of
millions, of mobile nodes. Careless application of the Home mobile nodes. Careless application of the Home Agent Switch
Agent Switch message may cause the new home agent, or some message may cause the new home agent, or some other parts of
other parts of the network, to suffer. As a result, it is the network, to suffer. As a result, it is REQUIRED that
REQUIRED that applications of this message either employ a applications of this message either employ a feedback loop
feedback loop between resources of the new home agent and the between resources of the new home agent and the sending of
sending of additional Home Agent Switch messages, or apply a additional Home Agent Switch messages, or apply a maximum rate
maximum rate at which mobile nodes can be informed of the at which mobile nodes can be informed of the switch that is far
switch that is far below the designated capacity of new below the designated capacity of new registrations that the set
registrations that the set of home agents can process. If no of home agents can process. If no other information is
other information is available, this maximum rate should available, this maximum rate should default to MAX-HA-SWITCH-
default to MAX-HA-SWITCH-TRANSMIT-RATE. TRANSMIT-RATE.
o In general, switching the home agent of a mobile node should o In general, switching the home agent of a mobile node should
only be done when absolutely necessary, since it might cause only be done when absolutely necessary, since it might cause a
a service disruption if the switch to a new home agent fails, service disruption if the switch to a new home agent fails, the
the new home agent is itself under an overload condition, or new home agent is itself under an overload condition, or the
the network connection of the new home agent is congested. network connection of the new home agent is congested.
Similarly, the path characteristics via the new home agent
may be different, which may cause temporary difficulties for Similarly, the path characteristics via the new home agent may
end to end transport layer operation. be different, which may cause temporary difficulties for end-
to-end transport layer operation.
o If this message is being used for load-balancing between a set o If this message is being used for load-balancing between a set
of home agents, they should all be configured with the same of home agents, they should all be configured with the same set
set of prefixes so a home agent switch does not require a of prefixes so a home agent switch does not require a change of
change of the home address for a mobile node. That operation the home address for a mobile node. That operation is NOT
is NOT RECOMMENDED and should be avoided. RECOMMENDED and should be avoided.
8. Procotol Constants 8. Protocol Constants
INITIAL-HA-SWITCH-TIMEOUT 5 seconds INITIAL-HA-SWITCH-TIMEOUT 5 seconds
MAX-HA-SWITCH-TIMEOUT 20 seconds MAX-HA-SWITCH-TIMEOUT 20 seconds
MAX-HA-SWITCH-TRANSMIT-RATE 1 per second MAX-HA-SWITCH-TRANSMIT-RATE 1 per second
9. IANA Considerations 9. IANA Considerations
A new Mobility Header type is required for the following new message IANA has assigned a new Mobility Header type for the following new
described in Section 4: message described in Section 4:
(TBD) Home Agent Switch message (12) Home Agent Switch message
10. Security Considerations 10. Security Considerations
As with other messages in [RFC3775], the Home Agent Switch message As with other messages in [RFC3775], the Home Agent Switch message
MUST use the home agent to mobile node ESP encryption SA for MUST use the home agent to mobile node ESP encryption SA for
confidentiality protection, and MUST use the home agent to mobile confidentiality protection, and MUST use the home agent to mobile
node ESP authentication SA for integrity protection. node ESP authentication SA for 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
[RFC3775], in order to reduce the number of configured security [RFC3775], 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 to on- Some operators may not want to reveal the list of home agents to on-
path listeners. In such a case, the Home Agent Switch message should path listeners. In such a case, the Home Agent Switch message should
use the home agent to mobile node IPsec ESP encryption SA for use the home agent to mobile node IPsec ESP encryption SA for
confidentiality protection. confidentiality protection.
11. References 11. References
11.1 Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3775] Johnson, D., Perkins, C., and Arkko, J., "Mobility Support [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility
in IPv6", RFC 3775, June, 2004. Support in IPv6", RFC 3775, June 2004.
11.2 Informative References 11.2. Informative References
[RFC4192] Baker, F., Lear, E., and Droms, R., "Procedures for [RFC4192] Baker, F., Lear, E., and R. Droms, "Procedures for
Renumbering an IPv6 Network without a Flag Day", RFC 4192, Renumbering an IPv6 Network without a Flag Day", RFC
September, 2005. 4192, September 2005.
[draft-mip6-hareliability] Wakikawa, R. (Editor), "Home Agent [hareliability] Wakikawa, R., Ed., "Home Agent Reliability Protocol",
Reliability Protocol", draft-ietf-mip6-hareliability-02.txt, July, Work in Progress, November 2007.
2007.
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 documents
that contributed content to this document: that contributed content to this RFC:
o draft-wakikawa-mip6-nemo-haha-spec-00.txt o Ryuji Wakikawa, Pascal Thubert, and Vijay Devarapalli,
o draft-deng-mip6-ha-loadbalance-02.txt "Inter Home Agents Protocol Specification", March 2006.
o draft-kempf-mip6-ha-alert-00.txt
o draft-haley-mip6-mh-signaling-00.txt o Hui Deng, Brian Haley, Xiaodong Duan, Rong Zhang, and Kai Zhang,
"Load Balance for Distributed Home Agents in Mobile IPv6",
October 2004.
o James Kempf, "Extension to RFC 3775 for Alerting the Mobile Node
to Home Agent Unavailability", October 2005.
o Brian Haley and Sri Gundavelli, "Mobility Header Signaling
Message", September 2007.
Thanks also to Kilian Weniger, Jixing Liu, Alexandru Petrescu, Jouni Thanks also to Kilian Weniger, Jixing Liu, Alexandru Petrescu, Jouni
Korhonen, and Wolfgang Fritsche for their review and feedback. Korhonen, and Wolfgang Fritsche for their review and feedback.
Author's Addresses Author's Addresses
Brian Haley Brian Haley
Hewlett-Packard Company Hewlett-Packard Company
110 Spitbrook Road 110 Spitbrook Road
Nashua, NH 03062, USA Nashua, NH 03062, USA
Email: brian.haley@hp.com EMail: brian.haley@hp.com
Vijay Devarapalli Vijay Devarapalli
Azaire Networks Azaire Networks
3121 Jay Street 3121 Jay Street
Santa Clara, CA 95054 USA Santa Clara, CA 95054 USA
Email: vijay.devarapalli@azairenet.com EMail: vijay.devarapalli@azairenet.com
James Kempf James Kempf
DoCoMo USA Labs DoCoMo USA Labs
181 Metro Drive 181 Metro Drive
Suite 300 Suite 300
San Jose, CA 95110 USA San Jose, CA 95110 USA
Email: kempf@docomolabs-usa.com EMail: kempf@docomolabs-usa.com
Hui Deng Hui Deng
China Mobile China Mobile
53A, Xibianmennei Ave. 53A, Xibianmennei Ave.
Xuanwu District Xuanwu District
Beijing 100053 Beijing 100053
China China
Email: denghui@chinamobile.com EMail: denghui@chinamobile.com
Full Copyright Statement Full Copyright Statement
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retain all their rights. retain all their rights.
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