NETLMM Working Group V. Devarapalli
Internet-Draft WiChorus
Intended status: Standards Track H. Lim
Expires: December 5, 2008 N. Kant
Stoke
S. Krishnan
Ericsson
June 3, 2008
Heartbeat Mechanism for Proxy Mobile IPv6
draft-devarapalli-netlmm-pmipv6-heartbeat-02.txt
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Abstract
Proxy Mobile IPv6 is a network-based mobility management protocol.
The mobility entities involved in the Proxy Mobile IPv6 protocol, the
Mobile Access Gateway (MAG) and the Local Mobility Anchor (LMA),
setup tunnels dynamically to manage mobility for a mobile node within
the Proxy Mobile IPv6 domain. This document describes a heartbeat
mechanism between the MAG and the LMA to detect failures quickly and
take appropriate action.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Heartbeat Mechanism . . . . . . . . . . . . . . . . . . . . . 3
3.1. Failure Detection . . . . . . . . . . . . . . . . . . . . 4
3.2. Restart Detection . . . . . . . . . . . . . . . . . . . . 5
3.3. Heartbeat Message . . . . . . . . . . . . . . . . . . . . 5
3.4. Restart Counter Mobility Option . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Introduction
Proxy Mobile IPv6 enables network-based mobility for IPv6 hosts that
do not implement any mobility protocols. The protocol is described
in detail in [2]. The Local Mobility Anchor (LMA) acts the anchor
for the mobile node sessions as long as the mobile node is attached
to the Proxy Mobile IPv6 domain. For the definition of Proxy Mobile
IPv6 domain, see [2]. The mobile node is at any time attached to a
Mobile Access Gateway (MAG) that manages mobility for the mobile
node. The MAG and the LMA set up IP-in-IP tunnels to tunnel all
traffic that belongs to the mobile node.
If the LMA crashes or if there is a communication problem on the path
between the MAG and the LMA, the MAG discovers this only when it
sends the next proxy Binding Update and gets no response from the
LMA. If a MAG becomes unreachable, the LMA can detect it only when
it starts receiving ICMP unreachable messages from an intermediate
router in response to data traffic the LMA tunnels to the MAG. For
some deployments of Proxy Mobile IPv6, it is desirable to detect the
LMA or the MAG reachability failure very early, so that appropriate
action could be taken. The appropriate actions, for example,
releasing resources, is out of scope for this document.
This document proposes a heartbeat mechanism between the MAG and the
LMA to detect the current status of reachability between them. The
heartbeat message is a mobility header message (protocol type 135).
The MAG and the LMA exchange heartbeat messages every few seconds to
detect if the other end is still reachable. The interval between
consecutive heartbeats is configurable.
2. Terminology
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 [1].
3. Heartbeat Mechanism
The MAG and the LMA exchange heartbeat messages every
HEARTBEAT_INTERVAL seconds to detect the current status of
reachability between them. A MAG typically initiates the heartbeat
exchange by sending a Heartbeat Request to the LMA. Each Heartbeat
Request contains a sequence number that is incremented sequentially.
The sequence number on the last Heartbeat Request message is always
recorded by the MAG. The HEARTBEAT_INTERVAL is carried in the
Heartbeat Request message. The Heartbeat message is described in
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more detail in Section 3.3.
A heartbeat message can be sent only if the MAG has at least one
proxy binding cache entry at the LMA for a mobile node attached to
the MAG. If there are no proxy binding cache entries at the LMA for
any of the mobile nodes attached to the MAG, then the heartbeat
messages MUST NOT be sent.
When the LMA receives a Heartbeat Request message, it responds with a
Heartbeat Response message. The sequence number and the heartbeat
interval in the Heartbeat Request message are recorded on the LMA.
If the heartbeat interval is different from the previously known
heartbeat interval from the MAG, the LMA stores the new heartbeat
interval. The LMA copies the sequence number from the Heartbeat
Request message onto the Heartbeat Response message. The Heartbeat
Interval field is set to 0 in the Heartbeat Response message.
The HEARTBEAT_INTERVAL SHOULD NOT be configured to a value less than
30 seconds. Sending heartbeat messages too often may become an
overhead on the path between the MAG and the LMA.
The LMA MAY also send a one-time Heartbeat Request message to the MAG
to check a MAG's reachability status. The Heartbeat Interval in the
Heartbeat Request message is set to 0 to indicate that it is a one-
time message and is not transmitted periodically. If a MAG receives
a Heartbeat Request message from the LMA, it MUST respond with a
Heartbeat Response message.
If the LMA or the MAG do not support the heartbeat messages, they
should respond with an ICMP Parameter Problem, Code 0, message to the
initiator. The 'Pointer' field in the ICMP Parameter Problem message
SHOULD point to the 'MH Type' field, indicating that the particular
Mobility Header message is not supported. When the ICMP Parameter
Problem message is received in response to Heartbeat Request message,
the initiating MAG or the LMA MUST NOT use heartbeat messages with
the other end again.
3.1. Failure Detection
If the MAG does not receive more than MISSING_HEARTBEATS_ALLOWED
number of responses from the LMA, it concludes that the LMA is not
reachable. The MISSING_HEARTBEATS_ALLOWED value is configurable on
the MAG. The MAG may then take appropriate action (out of scope for
this document).
The LMA also has a MISSING_HEARTBEATS_ALLOWED counter configured per
MAG. The LMA knows how often to expect a heartbeat message from the
MAG based on the Heartbeat Interval in the first Heartbeat Request
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message received from the MAG. If the LMA does not receive more than
MISSING_HEARTBEATS_ALLOWED Heartbeat Request messages from the MAG,
it concludes that the MAG is not reachable.
The LMA may also optionally send a Heartbeat Request message to the
MAG before concluding that the MAG is unreachable. The Heartbeat
Interval value is set to 0 to indicate that this is a one-time
heartbeat message and is not sent periodically. If the LMA does not
get a response from the MAG, it re-transmits the Heartbeat Request
message. The number of times the Heartbeat Request is re-transmitted
is configurable on the LMA. If a response from the MAG is received,
then the LMA concludes that the MAG is reachable and resets the
MISSING_HEARTBEATS_ALLOWED counter for the particular MAG.
3.2. Restart Detection
The section describes an optional extension for detecting failure
recovery without session persistence. In case the LMA crashes and
re-boots and looses all state with respect to the PMIPv6 sessions, it
would be beneficial for the MAGs to discover the failure recovery and
setup the sessions again. The following is applicable only if the
Restart Detection mechanism is used.
Each PMIPv6 node (both the MAG and LMA) MUST maintain a monotonically
increasing Restart Counter that is incremented every time the node
re-boots and looses PMIPv6 session state. The counter MUST NOT be
incremented if the recovery happens without losing state for the
PMIPv6 sessions active at the time of failure. This counter MUST be
stored in non-volatile memory. A PMIPv6 node includes a Restart
Counter mobility option, described in Section 3.4 in an Heartbeat
Response message to indicate the current value of the Restart
Counter. Each PMIPv6 node MUST also store the Restart Counter for
all the peer PMIPv6 nodes that it has sessions with currently.
Storing the Restart Counter values for peer PMIPv6 nodes does not
require non-volatile memory.
The PMIPv6 node that receives the Heartbeat Response message compares
the Restart Counter value with the previously received value. If the
value is different, the receiving node assumes that the peer PMIPv6
node had crashed and recovered. If the Restart Counter value changes
or if there was no previously stored value, the new value is stored
by the receiving PMIPv6 node.
3.3. Heartbeat Message
The following illustrates the message format for the Heartbeat
Mobility Header message. The 'MH Type' field in the Mobility Header
indicates that it is a Heartbeat message.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Heartbeat Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved
Set to 0 and ignored by the receiver.
'R'
A 1-bit flag that indicates whether the message is a request or a
response. When the 'R' flag is set to 0, it indicates that the
Heartbeat message is a request. When the 'R' flag is set to 1, it
indicates that the Heartbeat message is a response.
Sequence Number
A 32-bit sequence number used for matching the request to the
reply.
Heartbeat Interval
A 32-bit value indicating the interval in seconds between two
consecutive heartbeat messages. A value of 0 indicates that the
Heartbeat message is just a one-time message and not sent
periodically.
3.4. Restart Counter Mobility Option
The following shows the message format for a new mobility option for
carrying the Restart Counter Value in the Heartbeat message. The
Restart Counter Mobility Option is only valid in a Heartbeat Response
message. It has an alignment requirement of 4n+2.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Restart Counter |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Type
A 8-bit field that indicates that it is a Restart Counter mobility
option.
Length
A 8-bit field that indicates the length of the option in octets
excluding the 'Type' and 'Length' fields. It is set to '4'.
Restart Counter
A 32-bit field that indicates the current Restart Counter value.
4. Security Considerations
The heartbeat messages are just used for checking reachability
between the MAG and the LMA. They do not carry information that is
useful for eavesdroppers on the path. Integrity protection using
IPsec [3] for the heartbeat messages MUST be supported on the MAG and
the LMA. The use of IPsec protection is optional. Confidentiality
protection is not required.
For dynamic key negotiation between the MAG and the LMA, IKEv2 [4]
SHOULD be used.
5. IANA Considerations
The Heartbeat message defined in Section 3.3 must have the type value
allocated from the same space as the 'MH Type' field in the Mobility
Header defined in RFC 3775 [5].
The Restart Counter mobility option defined in Section 3.4 must have
the type value allocated from the same space as the Mobility Options
defined in RFC 3775 [5].
6. Acknowledgments
A heartbeat mechanism for a network-based mobility management
protocol was first described in [6]. The authors would like to thank
the members of a NETLMM design team that produced that document. The
mechanism described in this document also derives from the path
management mechanism described in [7].
We would like to thank Alessio Casati for first suggesting a fault
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handling mechanism for Proxy Mobile IPv6. We would also like to
thank Julien Laganier for proposing the Restart Detection mechanism.
7. References
7.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and
B. Patil, "Proxy Mobile IPv6", draft-ietf-netlmm-proxymip6-18
(work in progress), May 2008.
[3] Kent, S. and K. Seo, "Security Architecture for the Internet
Protocol", RFC 4301, December 2005.
[4] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC 4306,
December 2005.
7.2. Informative References
[5] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004.
[6] Giaretta, G., "The NetLMM Protocol",
draft-giaretta-netlmm-dt-protocol-02 (work in progress),
October 2006.
[7] 3rd Generation Partnership Project, "3GPP Technical
Specification 29.060 V7.6.0: "Technical Specification Group Core
Network and Terminals; General Packet Radio Service (GPRS); GPRS
Tunnelling Protocol (GTP) across the Gn and Gp interface
(Release 7)"", July 2007.
Authors' Addresses
Vijay Devarapalli
WiChorus
3950 North First Street
San Jose, CA 95134
USA
Email: vijay@wichorus.com
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Heeseon Lim
Stoke
5403 Betsy Ross Drve
Santa Clara, CA 95054
USA
Email: hlim@stoke.com
Nishi Kant
Stoke
5403 Betsy Ross Drive
Santa Clara, CA 95054
USA
Email: nishi@stoke.com
Suresh Krishnan
Ericsson
8400 Decarie Blvd.
Town of Mount Royal, QC
Canada
Email: suresh.krishnan@ericsson.com
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