draft-ietf-mip6-hareliability-01.txt   draft-ietf-mip6-hareliability-02.txt 
MIP6 Working Group R. Wakikawa (Editor) MIP6 Working Group R. Wakikawa (Editor)
Internet-Draft Keio University Internet-Draft Keio University
Intended status: Standards Track March 5, 2007 Intended status: Standards Track July 17, 2007
Expires: September 6, 2007 Expires: January 18, 2008
Home Agent Reliability Protocol Home Agent Reliability Protocol
draft-ietf-mip6-hareliability-01.txt draft-ietf-mip6-hareliability-02.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
The home agent can be a single point of failure when Mobile IPv6 is The home agent can be a single point of failure when Mobile IPv6 is
used in a system. It is critical to provide home agent reliability used in a system. It is critical to provide home agent reliability
in the event of a home agent crashing or becoming unavailable. This in the event of a home agent crashing or becoming unavailable. This
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7.1. Home Agent Address Configuration . . . . . . . . . . . . . 23 7.1. Home Agent Address Configuration . . . . . . . . . . . . . 23
7.2. Consideration of Routing and Neighbor Discovery 7.2. Consideration of Routing and Neighbor Discovery
Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 23 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 23
7.3. Home Agent List Management . . . . . . . . . . . . . . . . 24 7.3. Home Agent List Management . . . . . . . . . . . . . . . . 24
7.4. Detecting Home Agent Failure . . . . . . . . . . . . . . . 25 7.4. Detecting Home Agent Failure . . . . . . . . . . . . . . . 25
7.5. Home Agent Switch Over . . . . . . . . . . . . . . . . . . 26 7.5. Home Agent Switch Over . . . . . . . . . . . . . . . . . . 26
7.6. Processing Hello Messages . . . . . . . . . . . . . . . . 27 7.6. Processing Hello Messages . . . . . . . . . . . . . . . . 27
7.6.1. Requesting Hello Message . . . . . . . . . . . . . . . 27 7.6.1. Requesting Hello Message . . . . . . . . . . . . . . . 27
7.6.2. Sending Hello Message . . . . . . . . . . . . . . . . 27 7.6.2. Sending Hello Message . . . . . . . . . . . . . . . . 27
7.6.3. Receiving Hello Message . . . . . . . . . . . . . . . 28 7.6.3. Receiving Hello Message . . . . . . . . . . . . . . . 28
7.7. Processing State Synchronization Messages . . . . . . . . 28 7.7. Processing State Synchronization Messages . . . . . . . . 29
7.7.1. Soliciting State of a Particular Mobile Node or 7.7.1. Soliciting State of a Particular Mobile Node or
Subset of Mobile Nodes . . . . . . . . . . . . . . . . 29 Subset of Mobile Nodes . . . . . . . . . . . . . . . . 29
7.7.2. Synchronizing State of Mobile Nodes . . . . . . . . . 30 7.7.2. Synchronizing State of Mobile Nodes . . . . . . . . . 30
7.8. Processing Home Agent Control Messages . . . . . . . . . . 31 7.8. Processing Home Agent Control Messages . . . . . . . . . . 31
7.8.1. Standby Home Agent becomes an Active Home Agent . . . 31 7.8.1. Standby Home Agent becomes an Active Home Agent . . . 31
7.8.2. Active Home Agent becomes in-active . . . . . . . . . 32 7.8.2. Active Home Agent becomes in-active . . . . . . . . . 32
7.9. Sending Home Agent Switch Messages . . . . . . . . . . . . 32 7.9. Sending Home Agent Switch Messages . . . . . . . . . . . . 32
7.10. Interworking with VRRP . . . . . . . . . . . . . . . . . . 33 7.10. Interworking with VRRP . . . . . . . . . . . . . . . . . . 33
7.11. Retransmissions and Rate Limiting . . . . . . . . . . . . 35 7.11. Retransmissions and Rate Limiting . . . . . . . . . . . . 35
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check-point IPsec session state, including the per packet sequence check-point IPsec session state, including the per packet sequence
numbers, for the mobile node. Thus, we define two possible home numbers, for the mobile node. Thus, we define two possible home
agent redundancy modes as follows: agent redundancy modes as follows:
Home Agent Virtual Switch Home Agent Virtual Switch
Each mobile node negotiates just one SA with an active home agent Each mobile node negotiates just one SA with an active home agent
in a redundant home agent set. The IPsec state will be shared in a redundant home agent set. The IPsec state will be shared
within the redundant home agent set in the background. The active within the redundant home agent set in the background. The active
and the redundant home agents are addressed by the same home agent and the redundant home agents are addressed by the same home agent
address, although only tje active home agent is accessible by the address, although only the active home agent is accessible by the
home agent address all of the time. IPsec/IKE states must be home agent address all of the time. IPsec/IKE states must be
synchronized between the active and standby home agents. The synchronized between the active and standby home agents. The
mechanism used to synchronize IPsec state is considered out of mechanism used to synchronize IPsec state is considered out of
scope for this document. In case there is a failure of the active scope for this document. In case there is a failure of the active
home agent, the standby home agent takes over without the mobile home agent, the standby home agent takes over without the mobile
node being aware of the change in the home agent. node being aware of the change in the home agent.
In a redundant home agent set, a single home agent address is used In a redundant home agent set, a single home agent address is used
by the active home agent. Thus, all the mobile nodes served by a by the active home agent. Thus, all the mobile nodes served by a
redundant home agent set MUST associate with the same home agent redundant home agent set MUST associate with the same home agent
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different link (named the recovery link in Figure 2). HA3 and HA4 different link (named the recovery link in Figure 2). HA3 and HA4
are standby home agents of HA1 and HA2. In this case, HA3 and HA4 are standby home agents of HA1 and HA2. In this case, HA3 and HA4
cannot receive packets meant for the home network until the route on cannot receive packets meant for the home network until the route on
the Routers is changed. The advantage of this configuration is that the Routers is changed. The advantage of this configuration is that
standby home agents can recover from a failure of the home link. standby home agents can recover from a failure of the home link.
This configuration can achieve home agent recovery even if the entire This configuration can achieve home agent recovery even if the entire
home link fails. In this configuration, the routing must be also home link fails. In this configuration, the routing must be also
updated to direct the packets meant for the home link to the recovery updated to direct the packets meant for the home link to the recovery
link. link.
This geographic redundancy is not a requirement by any SDO (Standards This geographic redundancy is not a requirement by most SDOs
Development Organization), but is required by operators. Most large (Standards Development Organization), but is required by operators.
operators have a very stringent requirement on network availability Most large operators have a very stringent requirement on network
even in the worst type of disaster or outage. For example, critical availability even in the worst type of disaster or outage. For
nodes in region-1 are backed up by nodes in region-2. These two example, critical nodes in region-1 are backed up by nodes in
regions are geographically separated. If region-1 suffers a downtime region-2. These two regions are geographically separated. If
due to any reason, all the sessions will be seamlessly taken over by region-1 suffers a downtime due to any reason, all the sessions will
the nodes in region-2. This is called geographic redundancy. This be seamlessly taken over by the nodes in region-2. This is called
is a well-known configuration for Telecommunications operators. geographic redundancy. This is a well-known configuration for
Telecommunications operators.
5.2. Home Agent Virtual Switch 5.2. Home Agent Virtual Switch
A mobile node remains unaware about the change in the active home A mobile node remains unaware about the change in the active home
agent since the home agents have replicated all session state agent since the home agents have replicated all session state
including the IPsec/IKE/ESP states. The IPsec/IKE/ESP state transfer including the IPsec/IKE/ESP states. The IPsec/IKE/ESP state transfer
is out of scope of this document. is out of scope of this document.
MN HA1(active) HA2(Standby) MN HA1(active) HA2(Standby)
| | . | | .
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and mobile nodes, they can utilize both Router Advertisements and and mobile nodes, they can utilize both Router Advertisements and
Hello messages. Router Advertisements are used to carry the home Hello messages. Router Advertisements are used to carry the home
agent information for mobile nodes, and Hello message are used to agent information for mobile nodes, and Hello message are used to
carry information for Home Agent Reliability operation. If an carry information for Home Agent Reliability operation. If an
operator decides not to use the Hello messages, Router Advertisements operator decides not to use the Hello messages, Router Advertisements
MUST be used to update the home agent list. MUST be used to update the home agent list.
Since Hello messages carry all the necessary information filled-in Since Hello messages carry all the necessary information filled-in
from the home agent list, the management of the home agent list is from the home agent list, the management of the home agent list is
unchanged. If a standby home agent removes an active home agent from unchanged. If a standby home agent removes an active home agent from
the list because it's lifetime has become zero, it can start recovery the list because its lifetime has become zero, it can start recovery
according to this document. < xref target="subsec:failuredetection"/> according to this document. Section 7.4 describes failure detection
describes failure detection in detail. in detail.
7.4. Detecting Home Agent Failure 7.4. Detecting Home Agent Failure
The active and standby home agents can monitor each other's status in The active and standby home agents can monitor each other's status in
multiple ways. One method is to reuse other failure detection multiple ways. One method is to reuse other failure detection
mechanisms such as VRRP[4] and HSRP[5] described in Section 7.10. mechanisms such as VRRP[4] and HSRP[5] described in Section 7.10.
This document also defines its own method by using periodic exchanges This document also defines its own method by using periodic exchanges
of Hello messages to monitor status. The reasons to specify Hello of Hello messages to monitor status. The reasons to specify Hello
messages are: messages are:
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The Hello message MUST be sent when a home agent receives a Hello The Hello message MUST be sent when a home agent receives a Hello
message with the R-flag set, indicating a request is required, message with the R-flag set, indicating a request is required,
otherwise Hello messages are periodically sent according to the pre- otherwise Hello messages are periodically sent according to the pre-
configured Hello interval. In addition, a home agent SHOULD send a configured Hello interval. In addition, a home agent SHOULD send a
Hello message to the home agents of the redundant home agent set when Hello message to the home agents of the redundant home agent set when
it boots up and its local information, such as home agent preference, it boots up and its local information, such as home agent preference,
home agent lifetime, and registration status, etc., change. When a home agent lifetime, and registration status, etc., change. When a
new home agent boots up, it SHOULD solicit Hello messages by new home agent boots up, it SHOULD solicit Hello messages by
multicasting a Hello message with the R-flag set in parallel with multicasting a Hello message with the R-flag set in parallel with
sending own Hello message. sending its own Hello message.
Whenever a home agent generates Hello message, it MUST increment in Whenever a home agent generates Hello message, it MUST increment in
the Sequence Number by 1. It MUST also specify its own Group ID in the Sequence Number by 1. The Sequence Number SHOULD be initialized
the Group ID field of the Hello message. If a home agent is the to zero for the first Hello message. To accomplish sequence number
active home agent, it MUST set the A-flag in it's Hello Messages. In rollover, if the sequence number has already been assigned to be the
the Home Agent Hard Switch mode, the source address of Hello messages largest possible number representable as a 16-bit unsigned integer,
MUST be the configured home agent address. In the Home Agent Virtual then when it is incremented it will then have a value of zero (0).
Switch mode, the individual IPv6 addresses of each home agent MUST be It MUST also specify its own Group ID in the Group ID field of the
used. Hello message. If a home agent is the active home agent, it MUST set
the A-flag in it's Hello Messages. In the Home Agent Hard Switch
mode, the source address of Hello messages MUST be the configured
home agent address. In the Home Agent Virtual Switch mode, the
individual IPv6 addresses of each home agent MUST be used.
7.6.3. Receiving Hello Message 7.6.3. Receiving Hello Message
When a home agent receives a Hello message, it SHOULD verify IPsec When a home agent receives a Hello message, it SHOULD verify IPsec
ESP protection. If the message is not protected, it SHOULD be ESP protection. If the message is not protected, it SHOULD be
silently discarded. However, if the Hello messages is sent on a silently discarded. However, if the Hello messages is sent on a
dedicated link between the home agents, IPsec protection is not dedicated link between the home agents, IPsec protection is not
required. If a Hello message is sent from an IPv6 address whose required. If a Hello message is sent from an IPv6 address whose
scope is not global, the message MUST be silently discarded. scope is not global, the message MUST be silently discarded.
If the sending home agent is not in the same redundant home agent If the sending home agent is not in the same redundant home agent
set, the message MUST be silently ignored. This can be done by set, the message MUST be silently ignored. This can be done by
comparing the Group ID field of the received Hello message with the comparing the Group ID field of the received Hello message with its
own Group ID value. Hello messages MUST NOT be sent to a home agent own Group ID value. Hello messages MUST NOT be sent to a home agent
whose Group ID is different from the sender. If the Sequence Number whose Group ID is different from the sender. If the Sequence Number
value in the Hello message is equal to or less than the Sequence value in the Hello message is equal to or less than the Sequence
Number value stored in the home agent list entry, the Hello message Number value stored in the home agent list entry, the Hello message
MUST be discarded. MUST be discarded.
Any Hello message satisfying all of these tests MUST be processed to Any Hello message satisfying all of these tests MUST be processed to
update the redundant home agent list. The receiver copies home agent update the redundant home agent list. The receiver copies home agent
information in the Hello message to the corresponding redundant home information in the Hello message to the corresponding redundant home
agent list entry. The home agent address of the sender is retrieved agent list entry. The home agent address of the sender is retrieved
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7.7.1. Soliciting State of a Particular Mobile Node or Subset of Mobile 7.7.1. Soliciting State of a Particular Mobile Node or Subset of Mobile
Nodes Nodes
When a standby home agent wants state information for a particular When a standby home agent wants state information for a particular
mobile node or a subset of mobile nodes, such as Binding Cache, AAA, mobile node or a subset of mobile nodes, such as Binding Cache, AAA,
etc., it MAY solicit this state by sending a State Synchronization etc., it MAY solicit this state by sending a State Synchronization
message constructed as follows: message constructed as follows:
o It MUST set the Type field to 0 (Request). o It MUST set the Type field to 0 (Request).
o It MUST set a random value in the Identifier field. o It MUST set a random value in the Identifier field that does not
coincide with any other currently pending Requests.
o It MUST include either a Home Address mobility option indicating o It MUST include either a Home Address mobility option indicating
the mobile node, or a Mobile Network Prefix mobility option the mobile node, or a Mobile Network Prefix mobility option
indicating the mobile router. The standby home agent can send indicating the mobile router. The standby home agent can send
multiple home address and mobile network prefix mobility options multiple home address and mobile network prefix mobility options
to request state information for multiple mobile nodes in a single to request state information for multiple mobile nodes in a single
State Synchronization request message. State Synchronization request message.
When a home agent receives the State Synchronization message with the When a home agent receives the State Synchronization message with the
Type field set to 0 (Request), it MUST verify the message as follows: Type field set to 0 (Request), it MUST verify the message as follows:
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March 2006. March 2006.
[18] Faizan, J., "Problem Statement: Home Agent Reliability", [18] Faizan, J., "Problem Statement: Home Agent Reliability",
draft-jfaizan-mipv6-ha-reliability-01 (work in progress), draft-jfaizan-mipv6-ha-reliability-01 (work in progress),
February 2004. February 2004.
Appendix A. Change Log From Previous Versions Appendix A. Change Log From Previous Versions
Changes from draft-ietf-mip6-hareliability-00 Changes from draft-ietf-mip6-hareliability-00
o Combining State Synchronization Request message and State o comment (see mail at 2007 June 20) from Wesley Eddy, Verizon
Synchronization message Federal Network Systems
o Combining home agent SwitchOver Request & Reply and SwitchBack
Request & Reply messages.
o Many Editorial Changes
Author's Address Author's Address
Ryuji Wakikawa Ryuji Wakikawa (Editor)
Keio University Keio University
Department of Environmental Information, Keio University Department of Environmental Information, Keio University.
5322 Endo, Fujisawa, Kanagawa 252-8520 5322 Endo
Fujisawa, Kanagawa 252-8520
Japan Japan
Phone: +81-466-49-1100
Fax: +81-466-49-1395
Email: ryuji@sfc.wide.ad.jp Email: ryuji@sfc.wide.ad.jp
URI: http://www.wakikawa.org/
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
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