NETLMM Working Group D. Premec
Internet Draft Nokia Siemens Networks
Intended status: Informational B. Patil
Expires: January 2009 Nokia
S. Krishnan
Ericsson
July 14, 2008
Bulk Re-registration for Proxy Mobile IPv6
draft-premec-netlmm-bulk-re-registration-01.txt
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Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract
The Proxy Mobile IPv6 specification requires the Mobile Access
Gateway (MAG) to send a separate Proxy Binding Update (PBU) message
to the Local Mobility Agent (LMA) for each mobile node (MN) to renew
the MN's mobility binding. This document defines a mechanism by which
a MAG can update the mobility bindings of multiple MNs attached to it
with a single PBU message to the serving LMA. This mechanism is also
intended to be used by a MAG to re-establish bindings at a new LMA
when its old LMA fails.
Conventions used in this document
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 [RFC2119].
Table of Contents
1. Introduction...................................................3
2. Terminology....................................................4
3. Bulk Re-registration Overview..................................4
4. Message formats................................................6
4.1. Proxy Binding Update message..............................7
4.2. Proxy Binding Acknowledgment message......................8
5. MAG Operation..................................................8
6. LMA operation.................................................10
7. Security Considerations.......................................12
8. IANA Considerations...........................................12
9. Acknowledgments...............................................12
10. References...................................................13
10.1. Normative References....................................13
10.2. Informative References..................................13
Author's Addresses...............................................14
Intellectual Property Statement..................................14
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Disclaimer of Validity...........................................15
1. Introduction
According to the Proxy Mobile IPv6 (PMIP6) specification [Gun2008], a
netlmm domain is defined as a network which provides a network based
IP mobility service by deploying the PMIP6 protocol. A MAG performs
the mobility related signaling on behalf of a MN by sending the Proxy
Binding Update (PBU) message to a LMA. When the binding lifetime of a
particular MN is close to expiry, the MAG renews the registration of
the MN by sending a PBU message, to the LMA, requesting the extension
of the binding lifetime.
A single LMA serves multiple MAGs and the capacity of the LMA in
terms of the number of attached MNs can be quite large. It can be
expected that LMA capacity in managed networks may easily exceed
hundreds of thousands or more attached MNs.
The following simple formula gives an estimate of the average number
of re-registration transactions per second as a function of the
number of registered MNs and the binding lifetime period:
transactions/sec = (number of registered MNs) / (binding lifetime*4)
For 50.000 MNs and the binding lifetime of half an hour this gives:
50000 MNs / 1800 sec = 27,7 transactions/sec
Based on the above formula it is apparent that the default re-
registration process where the MAG sends a separate message for each
MN is inefficient or suboptimal. These re-registration messages
consume significant network resources both in terms of processing
power at the LMA and MAG and network bandwidth. In addition, since
the registration messages are sent per MN, there is no efficient way
for the MAG to recover from the failure of an LMA. It needs to resend
registration messages for each MN attached to it, towards a new LMA.
This increases the service disruption interval.
This document proposes an optimization of the re-registration process
by which the signaling load for re-registration can be reduced to a
single transaction per MAG, irrespective of the number of attached
MNs.
A MAG requests a bulk re-registration for a set of MNs by sending a
single PBU message with a new bulk re-registration flag (B) set to 1.
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The LMA extends the binding lifetime of MNs that are currently
attached to that MAG and meet the criteria contained in the renewals
request. If no current binding cache entry exists, the LMA creates
new bindings for the MNs listed in the bulk registration message. The
LMA indicates success of a bulk re-registration by responding with a
PBAck message with the bulk re-registration flag (B) set to 1. By
using this method, the MAG and LMA accomplish the re-registration of
MNs attached to a MAG in a single transaction. The number of re-
registration transactions at the LMA becomes independent of the
number of attached MNs; instead it is dependent only on the number of
MAGs.
2. Terminology
General mobility related terminology is defined in [RFC3775].
Additional PMIP6 specific terminology can be found in [Gun2008].
netlmm domain
Network providing the network based IP mobility service as
defined in [Gun2008].
PMIP6
Proxy Mobile IPv6 protocol specified in [Gun2008].
Bulk re-registration
PBU/PBAck message exchange where the bulk re-registration flag
(B) is set to 1.
bulk re-registration set
a set containing the MNs to which the request for bulk
re-registration applies.
3. Bulk Re-registration Overview
The bulk re-registration mechanism allows the MAG and LMA to extend
the binding lifetime for a number of MNs with a single transaction.
The MAG and LMA maintain a set of MNs that can be re-registered in
bulk mode. This set is called a bulk re-registration set and is a
subset of the MNs attached to a MAG. Initially the bulk re-
registration set is empty. MAG requests to add individual MNs to this
set by sending a regular PBU message that identifies an individual MN
and additionally the bulk re-registration flag in the message is set
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to 1. Based on the received bulk re-registration bit the LMA adds the
MN to the bulk re-registration set and responds with the PBAck
message with the bulk re-registration flag (B) set to 1.
Once there is a non-empty bulk re-registration set, MAG can request
to extend the binding lifetime of some or all MNs that are part of
the bulk re-registration set by sending a PBU message with bulk re-
registration flag set to 1 and omitting any options that would
identify an individual MN. In particular, the MAG may omit both the
MN ID (Mobile Node Identifier) option and the HNP (Home Network
Prefix) option in which case the MAG requests bulk re-registration of
all MNs in the bulk re-registration set. If the bulk registration
message is being sent to recover from an LMA failure the MAG MUST
explicitly identify all the MNs that are included in the bulk
registration set and provide all the mobility options that need to be
included in an initial PBU. Due to the size of these options, the MAG
may not be able to fit all the MNs attached to it into a single BU.
In this case the MAG will split the MNs across multiple PBUs. The
receiving LMA can use the information included in these bulk PBUs to
recreate the bul registration set, so that the MAG can renew the MNs'
lifetimes later with a single PBU.
There may be different triggers that cause the MAG to request a bulk
re-registration. Typically the trigger is the binding lifetime expiry
of a MN that is a member of a bulk re-registration set. There could
be other triggers as well, but they may be implementation or domain
specific and outside the scope of this specification.
The MAG may restrict the set of MNs to which the request for bulk re-
registration applies by including additional mobility options in the
PBU message that act as a filter. In this case only those MNs from
the bulk re-registration set which match the imposed restrictions
will be re-registered in a bulk mode. This filtering restriction is
valid only for the duration of the current re-registration
transaction. The binding cache entries of MNs that are members of
bulk re-registration set but not matching the filter will be left
unaffected. Following options may be used as a filter in a bulk re-
registration request:
1. Mobile Node Identifier (MN ID) option
This option can be used to select only MNs belonging to particular
domain, for example, by setting it to "@example.com".
2. Home Network Prefix (HNP) option
This option can be used to select MNs whose HNP matches the
indicated prefix for the first Prefix Length bits.
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3. Service Selection option [RFC5149]
This option can be used to select MNs whose Service Selection
option in the binding cache entry exactly matches the requested
Service Selection option in the PBU.
4. Vendor-Specific Mobility option [RFC5094]
This option can be used to select MNs whose Vendor-Specific option
in the binding cache entry matches the requested Vendor-Specific
option in the PBU.
If MN's binding cache entry does not match all of the filtering
options from the bulk re-registration request, then it is not
affected by this bulk re-registration operation.
The LMA extends the mobility binding of all MNs from the bulk re-
registration set that meet the filtering criteria and responds with
PBAck message with the bulk re-registration flag set to 1. The LMA
includes in its response the same mobility options that were included
in the request.
A MAG may remove a MN from a bulk re-registration set by sending a
regular PBU message identifying the MN to be removed and with the
bulk re-registration flag set to 0.
When requested to add a MN to the bulk re-registration set, the LMA
may reject the request. In this case the LMA processes the PBU
message as if the bulk re-registration flag was not set and responds
with PBAck message where the bulk re-registration flag is set to 0.
4. Message formats
This section introduces extensions to PBU and PBAck messages used in
this specification.
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4.1. Proxy Binding Update message
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|H|L|K|M|R|P|B| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 Proxy Binding Update message
A Binding Update message that is sent by a MAG to a LMA is referred
to as the "Proxy Binding Update" message; it is defined in the
[Gun2008]. A new flag (B) is included in the Binding Update message.
Bulk Re-registration Flag (B)
If the mobility options included in the message identify a single MN
and if the bulk re-registration flag (B) is set to 1, then the PBU
message is a request to add the MN to the bulk re-registration set.
If the bulk re-registration flag (B) is set to 0, then the PBU
message is sent to remove the MN from the bulk re-registration set.
If bulk re-registration flag (B) is set to 1 and the included
mobility options do not identify a single MN, then the PBU message is
a request to extend the lifetime of the MNs contained in the bulk re-
registration set and whose binding cache entries match the mobility
options from the message.
Mobility Options
For descriptions of these options, refer to [Gun2008]. When the bulk
re-registration flag is set to 1, the PBU message without Mobile Node
Identifier option and/or without HNP option is valid and is processed
as described in section 3.
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4.2. Proxy Binding Acknowledgment message
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status |K|R|P|B| Res. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 Proxy Binding Acknowledgment message
A Binding Acknowledgment message that is sent by a LMA to a MAG is
referred to as the "Proxy Binding Acknowledgment" message; it is
defined in the [Gun2008]. A new flag (B) is included in the Binding
Acknowledgment message.
Bulk Re-registration Flag (B)
A new flag (B) is included in the Binding Acknowledgment message to
indicate to the MAG that the requested bulk re-registration operation
was successful. The flag MUST NOT be set to the value of 1 if it was
not set to 1 in the corresponding PBU message.
Mobility Options
For descriptions of these options, refer to [Gun2008]. When the bulk
re-registration flag was set to 1 in the PBU message and Mobile Node
Identifier option and/or HNP option were not included, then the PBAck
message is also sent without those mobility options as described in
section 3.
5. MAG Operation
When a new MN attaches to a MAG, the MAG SHALL register the MN with
the LMA by sending the PBU message formatted as described in
[Gun2008]. Additionally, the MAG MAY set the bulk re-registration
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flag (B) in the PBU message to 1 to request the LMA to add the MN to
the set of MNs re-registered in a bulk mode. The decision to request
bulk re-registration mode for a MN is a matter of local policy at the
MAG and is outside the scope of this specification.
The MAG SHALL add the MN to its bulk re-registration set when it
receives a PBAck message with the bulk re-registration bit set to 1
and if the corresponding PBU message was requesting the LMA to add
the MN to the bulk re-registration set. The MAG SHALL maintain a
separate bulk re-registration set for each LMA.
When the binding lifetime of any MN contained in the bulk re-
registration set is about to expire, the MAG SHALL request the bulk
re-registration by sending the PBU message with a bulk re-
registration flag set to 1. Mobility options in such PBU message
SHALL NOT identify an individual MN.
In addition, the MAG MAY trigger a bulk re-registration at any time.
The policy and exact conditions for these additional triggers are
outside of scope of this specification.
A MAG MAY omit HNP and MN ID options from a PBU message requesting
bulk re-registration.
A MAG MAY include mobility options in a PBU requesting a bulk re-
registration to restrict the set of MNs updated by this transaction.
In this case the set of MNs affected by this bulk re-registration
operation is the subset of MNs contained in a bulk re-registration
set whose binding cache entries match the mobility options included
in the PBU message, as described in section 3.
If the bulk registration message is being sent to recover from an LMA
failure the MAG MUST explicitly identify all the MNs that are
included in the bulk registration set and provide all the mobility
options that need to be included in an initial PBU. Due to the size
of these options, the MAG may not be able to fit all the MNs attached
to it into a single BU. In this case the MAG MUST split the MNs
across multiple BUs.
When the MAG receives a PBAck message indicating success with the
bulk re-registration bit set to 1 in response to a PBU message
requesting the bulk re-registration, the MAG SHALL update the binding
lifetime of all affected MNs to the lifetime value contained in the
PBAck message. If in the case of bulk re-registration the PBAck
message repeatedly indicates an error, the MAG SHALL fall back to
individual re-registration mode.
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After successfully processing the PBAck message indicating successful
re-registration in bulk mode, the MAG MAY start a single timer to
oversee the binding lifetime of all attached MNs served by the LMA to
which it sent the bulk PBU message.
If the MAG sets the bulk re-registration bit to 1 in a PBU message
but the bulk re-registration bit (B) is set to 0 in a PBAck message,
the MAG SHALL process the PBAck message as per [Gun2008]. In
addition, the MAG SHALL infer that the LMA does not support bulk re-
registration procedure. The MAG SHALL switch to regular, per-MN re-
registration mode as described in [Gun2008]. The MAG MAY retry the
bulk re-registration procedure after sufficient time has elapsed from
the previous unsuccessful bulk re-registration. This amount of time
SHOULD be configurable at the MAG.
If the PBAck message indicates success and it contains the MN ID and
HNP options, the MAG SHALL update the binding of the MN indicated by
the MN ID and HNP options, regardless of the value of the bulk re-
registration bit (B) in the PBAck message.
6. LMA operation
When the LMA receives a PBU message with a bulk re-registration bit
(B) set to 1 and if the message contains MN ID and/or HNP options
identifying a single MN, the LMA SHALL first process the PBU message
as per [Gun2008]. Upon successful processing of the message, if the
bulk re-registration flag is set in the message, the LMA SHALL
continue processing of the PBU message as described further below for
bulk mode re-registrations.
If the PBU message contains multiple MNIDs and/or HNP options, and
the LMA cannot find a matching binding cache entry, the LMA MUST
consider this to be equivalent to receiving multiple PBUs with one
MNID and/or HNP option each.
If the bulk re-registration flag in the PBU message is set to 1 and
if included mobility options identify a single MN, the LMA MAY add
the MN to the set of MNs re-registered in a bulk mode, subject to the
local policy. The decision whether to enable bulk re-registration
mode for a MN is a matter of local policy at the LMA and is outside
the scope of this specification.
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If the LMA decides to accept the bulk re-registration mode for the
MN, it SHALL add the MN to the bulk re-registration set. The LMA
SHALL maintain the bulk re-registration set per MAG.
Upon adding the MN to the bulk re-registration set, the LMA SHALL
respond with the PBAck message containing the bulk registration bit
to 1.
The PBU message with the bulk re-registration bit (B) set to 1 but
without the MN ID and HNP options is a valid message and indicates a
request for bulk mode re-registration of all MNs that are members of
the bulk re-registration set.
If the bulk re-registration flag (B) is set in the PBU message and
included mobility options do not identify an individual MN, the LMA
SHALL extend the binding lifetime of all affected MNs attached to the
MAG that sent the bulk PBU. The affected MNs are those MNs that are
members of a bulk re-registration set and whose binding cache entries
match the mobility options included in the bulk PBU message. The
valid mobility options and their semantics are described in section
3.
The LMA SHOULD set the binding lifetime of all MNs re-registered in a
bulk mode to expire at the same point in time.
The LMA SHOULD copy the mobility options from the bulk re-
registration request into the PBAck message sent in response.
Upon successful processing of bulk mode re-registration request, the
LMA MUST respond with a PBAck message indicating success and it
SHOULD set the bulk re-registration bit (B) to 1. The lifetime in the
PBAck message indicates the time when binding cache entries of
affected MNs will expire.
The LMA MAY reject the request for bulk re-registration. In this case
the LMA MUST NOT update binding cache entries of any MNs and SHALL
respond with PBAck where the bulk re-registration bit is set to 1 and
the status code indicates the reason for rejection.
After successfully processing the bulk PBU message, the LMA MAY start
a single timer to oversee the binding lifetime of all MNs affected by
this bulk re-registration transaction.
When the LMA receives a PBU message requesting a (re-)registration of
a single MN from a MAG that successfully executed a bulk re-
registration procedure before and the lifetime of that bulk re-
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registration is not expired yet, the LMA MAY set the lifetime in the
PBAck message to match the remaining lifetime of the MNs contained in
the bulk re-registration set. As a result the LMA is not required to
start a separate timer to oversee the binding lifetime of this MN.
The LMA not supporting this specification ignores the bulk re-
registration bit (B) in a PBU message and processes the message as
per the baseline specification [Gun2008]. In this case the PBAck
message sent in response contains the bulk re-registration bit (B) is
set to 0.
If the LMA that does not support this specification receives a bulk
PBU message that does not contain any options identifying a
particular MN then the LMA responds with the PBAck message where the
status field contains one of the following error codes:
MISSING_HOME_NETWORK_PREFIX_OPTION
MISSING_MN_IDENTIFIER_OPTION
These error codes are defined in the baseline specification
[Gun2008].
7. Security Considerations
The bulk re-registration mechanism does not introduce any new
security threat or vulnerability to the PMIP6 specification.
8. IANA Considerations
None.
9. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
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10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3775] Johnson, D., Perkins, C., Arkko, J., "Mobility Support in
IPv6", RFC 3775, June 2004.
[Gun2008] Gundavelli, S., Ed., "Proxy Mobile IPv6", May 2008, draft-
ietf-netlmm-proxymip6-18.txt
10.2. Informative References
[RFC5149] J. Korhonen, U. Nilsson, V. Devarapalli, "Service Selection
for Mobile IPv6", RFC 5149, February 2008
[RFC5094] V. Devarapalli, A. Patel, K. Leung, "Mobile IPv6 Vendor
Specific Option", RFC 5094, December 2007
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Author's Addresses
Domagoj Premec
Nokia Siemens Networks
Heinzelova 70a
10000 Zagreb
Croatia
Email: domagoj.premec.ext@nsn.com
Basavaraj Patil
Nokia
6000 Connection Drive
Irving, TX 75039
USA
Email: basavaraj.patil@nokia.com
Suresh Krishnan
Ericsson
8400 Decarie Blvd.
Town of Mount Royal, QC
Canada
Phone: +1 514 345 7900 x42871
Email: suresh.krishnan@ericsson.com
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