Internet Engineering Task Force (IETF) F. Abinader, Ed.

Internet Engineering Task Force (IETF) F. Abinader, Ed.
Request for Comments: 6602 Instituto Nokia de Tecnologia
Category: Standards Track S. Gundavelli, Ed.
ISSN: 2070-1721 K. Leung
Cisco
S. Krishnan
Ericsson
D. Premec
Unaffiliated
May 2012

Bulk Binding Update Support for Proxy Mobile IPv6

Abstract

For extending the lifetime of a mobility session, the Proxy Mobile
IPv6 specification requires the mobile access gateway to send a Proxy
Binding Update message to the local mobility anchor on a per-session
basis. In the absence of signaling semantics for performing
operations with group-specific scope, this results in a significant
amount of signaling traffic on a periodic basis between a given
mobile access gateway and a local mobility anchor. This document
defines optimizations to the binding update and revocation operations
in Proxy Mobile IPv6 for performing operations with group-specific
scope with the use of a group identifier.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6602.

Copyright Notice

Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.

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RFC 6602 Bulk Binding Update Support May 2012

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction ....................................................3
2. Conventions and Terminology .....................................4
2.1. Conventions ................................................4
2.2. Terminology ................................................4
3. Bulk Binding Update Overview ....................................4
3.1. Motivation .................................................4
3.2. General Operation ..........................................5
4. Message Formats .................................................8
4.1. Extensions to Proxy Binding Update Message .................9
4.2. Extensions to Proxy Binding Acknowledgement Message .......10
4.3. Mobile Node Group Identifier Option .......................10
4.4. Status Codes ..............................................11
5. Protocol Considerations ........................................12
5.1. MAG Considerations ........................................12
5.1.1. Extensions to Binding Update List Entry
Data Structure .....................................12
5.1.2. Requesting Bulk Binding Update Support for
a Mobility Session .................................12
5.1.3. Supporting Bulk Binding Updates ....................14
5.2. LMA Considerations ........................................15
5.2.1. Extensions to Binding Cache Entry Data Structure ...15
5.2.2. Enabling Bulk Binding Update Support for a
Mobility Session ...................................16
5.2.3. Supporting Bulk Binding Updates ....................18
6. Protocol Configuration Variables ...............................20
6.1. Local Mobility Anchor - Configuration Variables ...........20
6.2. Mobile Access Gateway - Configuration Variables ...........20
7. IANA Considerations ............................................20
8. Security Considerations ........................................21
9. Acknowledgements ...............................................21
10. References ....................................................22
10.1. Normative References .....................................22
10.2. Informative References ...................................22

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1. Introduction

The Proxy Mobile IPv6 base specification [RFC5213] requires the
Mobile Node Identifier option to be present in the mobility signaling
messages, such as in the Proxy Binding Update (PBU) and Proxy Binding
Acknowledgement (PBA) messages. It essentially limits the
operational scope of the binding update operation to a single
mobility session. These signaling messages lack the capability to
identify a group of mobility sessions, so the operations related to
binding update and revocation can be performed on all the mobility
sessions that are part of that group.

There is a need to have semantics for associating a group identity to
a mobility session, so the scope of the operations related to binding
update and revocation can be extended to all the mobility sessions
identified by the group identifier. The group identifier therefore
provides a considerably improved mechanism for protocol operations
that would otherwise require multiple atomic transactions on a per-
mobility-session basis. Following are some of the use cases where
the group identifier can be used.

o For extending the lifetime of a mobility session, the mobile
access gateway (MAG) periodically sends a Proxy Binding Update
message to the local mobility anchor (LMA) on a per-session basis.
This process can be optimized by allowing the mobile access
gateway to send a single Proxy Binding Update [RFC5213] message
for a group of mobility sessions identified by a group identifier.
Upon accepting the request, the local mobility anchor can update
the lifetime of all the mobility sessions that are part of that
group.

o On detecting the failure of a specific service card, a local
mobility anchor, or a mobile access gateway service hosted on
blade architecture system, can potentially request the peer to
revoke all the sessions identified by a common group identifier
that are hosted on that service card. Potentially, a single
Binding Revocation Indication [RFC5846] message carrying the group
identifier can be used to revoke all the sessions hosted on that
service card, which otherwise needs to be handled on a per-session
basis.

This document defines a new mobility option, the Mobile Node Group
Identifier option, and the extensions to procedures related to
binding update and binding revocation for performing binding
operations with group-specific scope.

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2. Conventions and Terminology

2.1. Conventions

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 RFC 2119 [RFC2119].

2.2. Terminology

All the mobility-related terms used in this document are to be
interpreted as defined in the base Proxy Mobile IPv6 specifications
[RFC5213] and [RFC5844]. Additionally, this document uses the
following terms:

Bulk Binding Update

A binding update operation that has group-specific scope. A
binding operation is associated with a specific mobility session.
However, a bulk binding update operation is associated with
multiple mobility sessions. This operation is not relevant for
new mobility session creation.

Bulk Binding Update Group

A group of mobility sessions that are part of the same logical
group and therefore share a common group identifier. This group
is the bulk binding update group. This bulk binding update group
is maintained by both the mobile access gateway and the local
mobility anchor, and the grouping logic is local to that node. A
mobility session can therefore be identified by two bulk binding
update group identifiers, one specific group created by the mobile
access gateway and the other specific group created by the local
mobility anchor. The bulk binding update group identifiers are
exchanged as part of the initial mobility session creation. The
mobility entities thereafter can perform operations related to
binding update such as lifetime extension and revocation
operations on an entire bulk binding update group identified by
the group identifier.

3. Bulk Binding Update Overview

3.1. Motivation

In a typical Proxy Mobile IPv6 domain, a local mobility anchor serves
multiple mobile access gateways, and the capacity of that node with
respect to the number of mobility sessions that it can host is quite
high, typically in the order of a few millions. As the number of

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mobility sessions hosted by a local mobility anchor goes up, so does
the amount of signaling traffic related to periodic binding update
traffic.

The currently specified approach of the binding update procedure for
extending the lifetimes of multiple mobility sessions (where the
mobile access gateway is required to send a unique binding update
message for each mobility session even when there is no change to the
session state) is inefficient or sub-optimal. These periodic binding
update messages consume a significant amount of network resources at
both the peers, in terms of processing power and network bandwidth.
There is an opportunity to optimize the signaling procedures by
allowing the local mobility anchor and the mobile access gateway to
perform bulk binding update operations. This document specifies
extensions to Proxy Mobile IPv6 signaling for performing binding
update and revocation operations on a group of mobility sessions.
These extensions do not take away the existing functionality of
performing binding operations on a single mobility session.

3.2. General Operation

The bulk binding update mechanism specified in this document allows
the mobile access gateway and the local mobility anchor to perform
binding update and revocation operations on a group of mobility
sessions. As part of the initial signaling during mobility session
establishment, the local mobility anchor and the mobile access
gateway exchange the respective bulk binding update group identifiers
for that mobility session. Subsequently, both the peers can perform
bulk operations on those groups by presenting the bulk binding update
group identifier in the signaling messages.

When sending a Proxy Binding Update message after detecting a new
mobile node on its access link, a mobile access gateway can request
the local mobility anchor to assign a bulk binding update group
identifier for the mobile node's mobility session. This is indicated
by setting the (B) flag in the Proxy Binding Update to a value of
(1). The mobile access gateway will also assign a bulk binding
update group identifier (or it may assign a default bulk binding
update group - ALL-SESSIONS) and include that in the Mobile Node
Group Identifier option.

Upon accepting the request, the local mobility anchor will group the
mobility session to a specific bulk binding update group (or it may
assign it to the default bulk binding update group - ALL-SESSIONS)
and return this bulk binding update group identifier in a Proxy
Binding Acknowledgement message. It will also set the (B) flag in

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the Proxy Binding Acknowledgement message to a value of (1). The
bulk binding update group identifier is carried in the Mobile Node
Group Identifier option, described in Section 4.3.

Once the bulk binding update group identifiers are exchanged, the
local mobility anchor and the mobile access gateway can perform
binding operations on those entire groups, by including the bulk
binding update group identifier in the signaling messages. For
example, the mobile access gateway can extend the lifetime of all the
mobility sessions that are part of a group by sending a single Proxy
Binding Update message with that bulk binding update group
identifier. Similarly, the local mobility anchor can revoke all the
mobility sessions that are part of a group by including that group
identifier in the Proxy Binding Revocation message. When initiating
bulk binding update operations on a group of mobility sessions, the
group identifier that is carried in the Mobile Node Group Identifier
option is always the identifier of the local group, and not the
identifier of the group on the peer.

Figure 1 explains the operational sequence of the bulk binding update
and revocation operations on a group of mobile nodes (MN1, MN2, and
MN3).

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MAG LMA
(1) | |
MN1-------| (2) PBU |
|--------------------------->|
| * (3)
| (4) PBA |
|<---------------------------|
* (5) |
(6) | |
MN2-------| |
* (7)........................|
(8) | |
MN3-------| |
* (9)........................|
| |
| (10) PBU |
|--------------------------->|
| * (11)
| (12) PBA |
|<---------------------------|
* (13)
| |
| (14) BRI |
|<---------------------------|
| * (15)
| (16) BRA |
|--------------------------->|
* (17) |
| |

Figure 1: Exchange of Group Identifier

o (1) to (2): The MAG detects the mobile node's (MN1) attachment to
the access link. The MAG groups the mobile node to a specific
bulk binding update group, (M1). The MAG notifies this group
identifier to the LMA by including it in the Mobile Node Group
Identifier option of the PBU message.

o (3): Upon accepting the PBU, the LMA creates a mobility session
and groups the mobility session to a specific bulk binding update
group, (L1). The LMA updates the mobile node's Binding Cache
entry to include the bulk binding update group identifier, (L1),
and the bulk binding update group identifier presented by the MAG,
(M1). The LMA also notifies the MAG about the bulk binding update
group identifier (L1), by including it in the PBA.

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o (4) to (5): Upon receiving the PBA, the MAG updates the Binding
Update List entry for that mobility session to include the bulk
binding update group identifiers (L1) and (M1). At this point,
both the LMA and MAG are aware of the mobile node's bulk binding
update group identifiers assigned by the peers.

o (6) to (9): The above steps (1 through 5) are repeated here for
MN2 and MN3; details are omitted. At the end of step (9), the MAG
completes the signaling with the LMA. The MAG assigns the mobile
nodes MN2 and MN3 to bulk binding update groups (M1) and (M2)
respectively, while the LMA assigns them both to the same bulk
binding update group, (L1).

o At this point, LMA has assigned MN1, MN2, and MN3 to the bulk
binding update group (L1), while the MAG has assigned MN1 and MN2
to group (M1) and MN3 to group (M2). Both peers can now perform
binding operations on a group of mobility sessions identified by
the respective bulk binding update group identifier.

o (10) to (13): The MAG sends a Proxy Binding Update message for
extending the lifetime of all the mobility sessions that are part
of the bulk binding update group (M1). It includes the bulk
binding update group identifier (M1) in the PBU. Upon accepting
the PBU, the LMA extends the lifetime of both MN1 and MN2, which
are part of the group (M1).

o (14) to (17): The LMA decides to revoke all the sessions that are
part of bulk binding update group (L1). The LMA sends a Binding
Revocation Indication (BRI) message with the bulk binding update
group identifier (L1). Upon accepting the BRI message, the MAG
revokes all the MN1, MN2, and MN3 mobility sessions, which are
part of that bulk binding update group (L1), and sends a Binding
Revocation Acknowledgement (BRA) [RFC5846] message.

4. Message Formats

This section identifies the extensions to Proxy Mobile IPv6 signaling
messages that are required for supporting this specification.

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4.1. Extensions to 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|F|T|B| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: Extensions to Proxy Binding Update Message

A new flag, the Bulk-Binding-Update flag (B), is defined in the Proxy
Binding Update message specified in [RFC5213]. The bit value of
Bulk-Binding-Update flag (B) in the flags field of the message will
be 0x0040.

If the Bulk-Binding-Update flag (B) is set to a value of (1), it
informs the local mobility anchor to enable bulk binding update
support for the mobility session associated with this message. If
the (B) flag is set to a value of (0), the local mobility anchor MUST
exclude the mobility session associated with this message from any
bulk-binding-related operations and any binding update, or binding
revocation operations with bulk-specific scope will not be relevant
to that mobility session.

This flag is relevant only for Proxy Mobile IPv6 and therefore MUST
be set to the value of (0) when the (P) flag is set to a value of
(0).

All other fields in the Proxy Binding Update message and the mobility
options that can be carried in the message conform to the appropriate
specifications.

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4.2. Extensions to Proxy Binding Acknowledgement 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|T|B| Res.|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 3: Extensions to Proxy Binding Acknowledgement Message

A new flag, the Bulk-Binding-Update flag (B), is defined in the Proxy
Binding Acknowledgement message specified in [RFC5213]. The bit
value of Bulk-Binding-Update flag (B) in the flags field of the
message is 0x08.

If the Bulk-Binding-Update flag (B) is set to a value of (1), it
serves as an indication to the mobile access gateway that the local
mobility anchor has enabled bulk binding update support for the
mobility session associated with this message. The value of the flag
MUST be set to the value of (0) if the value of the (B) flag in the
Proxy Binding Update message that it received from the mobile access
gateway was set to a value of (0).

This flag is relevant only for Proxy Mobile IPv6 and therefore MUST
be set to a value of (0) when the (P) flag is set to a value of (0).

All other fields in the Proxy Binding Acknowledgement message and the
mobility options that can be carried in the message conform to the
appropriate specifications.

4.3. Mobile Node Group Identifier Option

A new option, the Mobile Node Group Identifier option, is defined for
use in Proxy Mobile IPv6 signaling messages exchanged between a local
mobility anchor and a mobile access gateway. This option is used for
carrying the mobile node's group identifier. There can be multiple
instances of this option in a given signaling message; however, each
of the instances SHOULD have a different sub-type value. This option
is a generic option, and this specification uses only the sub-type
value of (1).

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The type value for this option is 50.

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 | Sub-type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mobile Node Group Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 4: Mobile Node Group Identifier Option

Type
<50>

Length
This is an 8-bit unsigned integer indicating the length in octets
of this option, excluding the type and length fields. The value
for this field MUST be set to a value of (6).

Sub-type
This 8-bit field identifies the specific mobile node's group type.
This number space will be managed by the IANA. The sub-type value
of (1) is reserved for the Bulk Binding Update Group.

Reserved
This 8-bit field is unused for now. The value MUST be initialized
to (0) by the sender and MUST be ignored by the receiver.

Mobile Node Group Identifier
This 32-bit field contains the mobile node's group identifier.
The value of (0) is reserved and SHOULD NOT be used. The value of
(1) ALL-SESSIONS is the default group of all mobility sessions
established between a given local mobility anchor and a mobile
access gateway.

4.4. Status Codes

This document defines the following new status code values for use in
the Proxy Binding Acknowledgement message. These values have been
allocated from the same number space as defined in Section 6.1.8 of
[RFC6275].

INVALID_MOBILE_NODE_GROUP_IDENTIFIER: 175

Invalid group identifier value in the request

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5. Protocol Considerations

5.1. MAG Considerations

The following are the considerations relevant to the mobile access
gateway when supporting this specification.

5.1.1. Extensions to Binding Update List Entry Data Structure

The conceptual Binding Update List entry data structure maintained by
the mobile access gateway, described in Section 6.1 of [RFC5213], is
extended to include the following REQUIRED additional fields:

o MAG-Bulk-Binding-Update-Group-Id
This is the bulk binding update group identifier assigned by this
mobile access gateway for this mobility session. It is a 32-bit
unsigned integer. This identifier is not globally unique within a
Proxy Mobile IPv6 domain; the same group identifier value may be
used by other nodes.

o LMA-Bulk-Binding-Update-Group-Id
This is the bulk binding update group identifier assigned by the
local mobility anchor for this mobility session. It is a 32-bit
unsigned integer. This identifier is received in the Mobile Node
Group Identifier option of the Proxy Binding Acknowledgement
message. This identifier is not globally unique within a Proxy
Mobile IPv6 domain; the same group identifier value may be used by
other nodes.

5.1.2. Requesting Bulk Binding Update Support for a Mobility Session

The following are the considerations for the mobile access gateway
for requesting bulk binding update support for a mobility session.

o When sending a Proxy Binding Update message to the local mobility
anchor, the mobile access gateway can choose to request that the
local mobility anchor enable bulk binding update support for the
mobility session associated with that Proxy Binding Update
request. When making such request, the Bulk-Binding-Update flag
(B) in the request MUST be set to a value of (1) and the Mobile
Node Group Identifier option MUST be present. The decision to
request bulk binding update support for a mobile node is a matter
of local policy at the mobile access gateway and is controlled by
the configuration variable
RequestBulkBindingUpdateSupportForMobilitySession.

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o The mobile access gateway MUST assign a bulk binding update group
identifier for the mobility session. Considerations on how the
mobile access gateway assigns a group identifier to a mobility
session is outside the scope of this document. This group
identifier can be unique to the service card on which the mobility
session is hosted or based on other grouping considerations. When
no such group assignment is done, the mobile access gateway SHOULD
assign the default group identifier value of (ALL-SESSIONS). This
assigned group identifier value MUST be present in the Mobile Node
Group Identifier option, and the sub-type value in the option MUST
be set to the value of (1) (Bulk Binding Update Group).

o If the received Proxy Binding Acknowledgement message has the
status code value set to (0) (Proxy Binding Update accepted) and
the Bulk-Binding-Update flag (B) set to a value of (0), in
response to a Proxy Binding Update request with the Bulk-Binding-
Update flag (B) set to a value of (1), it is an indication that
the local mobility anchor has denied the request for enabling bulk
binding update support for that mobility session and that the
mobility session is not associated with any bulk binding update
group. The mobile access gateway SHOULD set the bulk binding
update group identifier values LMA-Bulk-Binding-Update-Group-Id
and MAG-Bulk-Binding-Update-Group-Id to (0) in the Binding Update
List entry for that mobility session. Furthermore, the mobility
session should be excluded from any bulk binding update
operations.

o If the received Proxy Binding Acknowledgement message has the
status code value set to (0) (Proxy Binding Update accepted) and
the Bulk-Binding-Update flag (B) in the reply is set to a value of
(1), it is an indication that the local mobility anchor has
accepted the request to allow bulk binding update support for that
mobility session. Furthermore, the Mobile Node Group Identifier
option in the reply, with the sub-type value of (1) (Bulk Binding
Update Group), contains the bulk binding update group identifier
for that mobility session assigned by the local mobility anchor.
The mobile access gateway MUST update the LMA-Bulk-Binding-Update-
Group-Id and MAG-Bulk-Binding-Update-Group-Id parameters in the
Binding Update List entry for that mobility session. However, if
the received Proxy Binding Acknowledgement message has the Bulk-
Binding-Update flag (B) set to a value of (1), but the Mobile Node
Group Identifier option is not present, the message MUST be
considered malformed and ignored.

o If, at any point in time, the mobile access gateway chooses to
request the local mobility anchor to disable bulk binding update
support for a mobility session, it MUST send a Proxy Binding
Update message with the (B) flag set to a value of (0), and the

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Mobile Node Group Identifier option MUST NOT be present. This
message is sent as a normal binding update request for lifetime
extension. Requirements from Section 6.9.1 of [RFC5213] apply.
Furthermore, the mobile access gateway MUST update the Binding
Update List entry by setting the bulk binding update group
identifier values LMA-Bulk-Binding-Update-Group-Id and MAG-Bulk-
Binding-Update-Group-Id to (0), and the mobility session MUST be
excluded from any bulk binding update operations.

5.1.3. Supporting Bulk Binding Updates

The following section identifies the considerations for a mobile
access gateway performing binding update and revocation operations
with group-specific scope.

o For extending the lifetime of all mobility sessions that share the
same bulk binding update group identifier, the mobile access
gateway can choose to send a bulk binding update request. To make
such a request, it can send a Proxy Binding Update message to the
local mobility anchor, including the Mobile Node Group Identifier
option with the sub-type value of (1) (Bulk Binding Update Group)
and with the Bulk-Binding-Update flag (B) set to a value of (0).
The identifier value in the option MUST be set to the bulk binding
update group identifier of the group for which bulk binding update
operation is being requested. The message MUST NOT include any
individual session identifiers such as the Mobile Node Identifier
option [RFC4283], the Home Network Prefix option [RFC5213], the
IPv4 Home Address Request option [RFC5844], or the GRE Key option
[RFC5845]. All the considerations from Section 5.3.3 of [RFC5213]
MUST be followed when sending the bulk binding update request,
with the exception related to the use of Mobile Node Group
Identifier option in place of the individual session identifiers
(Mobile Node Identifier option, Home Network Prefix option, GRE
Key option, and IPv4 Home Address Request option).

o When requesting binding revocation for all the sessions that share
the same bulk binding update group identifier, the mobile access
gateway can choose to send a bulk revocation request. To make
such a request, it can send a Binding Revocation Indication
message [RFC5846] to the local mobility anchor, including the
Mobile Node Group Identifier option with the sub-type value of (1)
(Bulk Binding Update Group). The identifier value in the option
MUST be set to the bulk binding update group identifier of the
group for which bulk binding update operation is being requested.
The message MUST NOT include any individual session identifiers
such as the Mobile Node Identifier option [RFC4283], the Home
Network Prefix option [RFC5213], the IPv4 Home Address Request
option [RFC5844], or the GRE Key option [RFC5845]. All the

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considerations from Section 9.2 of [RFC5846] MUST be followed when
sending the bulk binding update request, with the exception
related to the use of Mobile Node Group Identifier option in place
of the individual session identifiers (Mobile Node Identifier
option, Home Network Prefix option, GRE Key option, IPv4 Home
Address Request option).

o Any time the mobile access gateway receives a Binding Revocation
Indication message [RFC5846], with a Mobile Node Group Identifier
option present in the request and with the sub-type value of (1)
(Bulk Binding Update Group), this message serves as a bulk
revocation request, with the request scope for revoking of all the
mobility sessions that are part of that bulk binding update group
specific to that local mobility anchor and identified by the group
identifier in the Mobile Node Group Identifier option.

o All the considerations from [RFC5846] apply when processing a
binding revocation request, except making the scope of the
operation apply to a set of mobility sessions identified by the
bulk binding update group identifier present in the request.

o If the received Binding Revocation Indication message includes the
Mobile Node Identifier option [RFC4283], the Home Network Prefix
option [RFC5213], the IPv4 Home Address Request option [RFC5844],
or the GRE Key option [RFC5845], the mobile access gateway MUST
consider this as an invalid message; it MUST reject the Binding
Revocation Indication message and send a Binding Revocation
Acknowledgement message with the Status field set to a value of
128 (Binding Does NOT Exist).

5.2. LMA Considerations

The following are the considerations relevant to a local mobility
anchor when supporting this specification.

5.2.1. Extensions to Binding Cache Entry Data Structure

The conceptual Binding Cache entry data structure maintained by the
local mobility anchor, described in Section 5.1 of [RFC5213], is
extended to include the following REQUIRED additional fields.

o MAG-Bulk-Binding-Update-Group-Id

This is the bulk binding update group identifier assigned by the
mobile access gateway for this mobility session. It is a 32-bit
unsigned integer. This identifier is received in the Mobile Node
Group Identifier option of the Proxy Binding Update message. This

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RFC 6602 Bulk Binding Update Support May 2012

identifier is not globally unique within a Proxy Mobile IPv6
domain; the same group identifier value may be used by other
nodes.

o LMA-Bulk-Binding-Update-Group-Id

This is the bulk binding update group identifier assigned by this
local mobility anchor for this mobility session. It is a 32-bit
unsigned integer. This identifier is not globally unique within a
Proxy Mobile IPv6 domain; the same group identifier value may be
used by other nodes.

5.2.2. Enabling Bulk Binding Update Support for a Mobility Session

The local mobility anchor will process a received Proxy Binding
Update message as specified in [RFC5213]. However, if the (B) flag
in the received Proxy Binding Update message is set to a value of (1)
and if it includes a Mobile Node Group Identifier option with the
sub-type value of (1) (Bulk Binding Update Group), the following
processing takes place:

o If the (B) flag in the received Proxy Binding Update message is
set to a value of (1) and if the Mobile Node Group Identifier
option is present in the request, the message serves as a request
to the local mobility anchor to enable bulk binding update support
for that mobility session.

o Upon successful processing and acceptance of the Proxy Binding
Update, the local mobility anchor can choose to enable bulk
binding update support for this mobility session. The decision
whether to enable bulk binding update support for that mobility
session is a matter of local policy and is controlled by the
configuration variable
AcceptBulkBindingUpdateReqForMobilitySession.

o For enabling the bulk binding update support for the mobility
session, the local mobility anchor MUST associate the mobility
session to a specific bulk binding update group locally. The
specific details on how the local mobility anchor associates the
given mobility session to a specific bulk binding update group is
outside the scope of this document. The local mobility anchor can
choose to assign a default bulk binding update group identifier
value of (ALL-SESSIONS), indicating that all the mobility sessions
from that mobile access gateway are part of that group. The local
mobility anchor SHOULD update the bulk binding update group
identifier values in the Binding Cache entry, LMA-Bulk-Binding-
Update-Group-Id and MAG-Bulk-Binding-Update-Group-Id, to the
respective values.

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o If the bulk binding update support is enabled for the mobile
node's mobility session, the local mobility anchor MUST send the
assigned bulk binding update group identifier as part of the
Mobile Node Group Identifier option, with the sub-type value of
(1) (Bulk Binding Update Group) in the Proxy Binding
Acknowledgement message that it sends to the mobile access
gateway. The (B) flag in the Proxy Binding Acknowledgement
message MUST be set to value of (1).

o If the bulk binding update support is not enabled for the mobility
session, the local mobility anchor MUST NOT include the Mobile
Node Group Identifier option with the sub-type value of (1) (Bulk
Binding Update Group), in the Proxy Binding Acknowledgement
message that it sends to the mobile access gateway. Furthermore,
the (B) flag in the Proxy Binding Acknowledgement message MUST be
set to value of (0). It is to be noted that the Mobile Node Group
Identifier option is a generic option and new sub-types may be
defined by future specifications.

o If the received Proxy Binding Update message is not a bulk binding
update request, (i.e., the (B) flag is set to a value of (0) and
the Mobile Node Group Identifier option with the sub-type value of
(1) (Bulk Binding Update Group) is not present), but is a request
for extending the lifetime of an existing mobility session, for
which the bulk binding update support is already enabled, then the
local mobility anchor MUST process the request as specified in
[RFC5213]. However, the value of (0) in the (B) flag in the
message serves as a request for the local mobility anchor to
disable bulk binding update support for that mobility session.
Upon accepting the request, the local mobility anchor SHOULD set
the parameters, LMA-Bulk-Binding-Update-Group-Id and MAG-Bulk-
Binding-Update-Group-Id in the Binding Cache entry to a value of
(0) and the mobility session MUST be excluded from any bulk
binding update operations.

o Any time the local mobility anchor detects that the mobile node
has roamed and changed its point of attachment to a new mobile
access gateway, it SHOULD also update the bulk binding update
group identifier of the mobility session. Additionally, it should
also update the existing group identifiers associated with that
session. As part of sending the Proxy Binding Acknowledgement to
the new mobile access gateway, it MUST include the updated group
identifier in the Mobile Node Group Identifier option, with a sub-
type value of (1). However, if the if the received Proxy Binding
Update from the new mobile access gateway did not have the (B)
flag set to a value of (1), then it MUST NOT include the mobility

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RFC 6602 Bulk Binding Update Support May 2012

session in any of bulk binding update group and MUST NOT include
the Mobile Node Group Identifier option with the sub-type value of
(1).

o Any time a mobile node's mobility session is de-registered by the
mobile access gateway, or the session is revoked for
administrative or any other reasons, the mobility session MUST
also be removed from the bulk binding update group.

5.2.3. Supporting Bulk Binding Updates

The following section identifies the considerations for a local
mobility anchor for performing bulk binding update and revocation
operations with group-specific scope.

o Any time the local mobility anchor receives a Proxy Binding Update
message with the (B) flag in the request set to a value of (0) and
a Mobile Node Group Identifier option present in the request with
sub-type value of (1) (Bulk Binding Update Group), the local
mobility anchor MUST consider the request a bulk binding update
request, with the request scope including all the mobility
sessions that are part of that bulk binding update group, specific
to that mobile access gateway, and identified by the group
identifier in Mobile Node Group Identifier option. However, if
the received request also includes any individual session
identifiers such as the Mobile Node Identifier option [RFC4283],
the Home Network Prefix option [RFC5213], the IPv4 Home Address
Request option [RFC5844], or the GRE Key option [RFC5845], the
local mobility anchor MUST consider this as an invalid message; it
MUST reject the Proxy Binding Update message and send a Proxy
Binding Acknowledgement message with the Status field set to
INVALID_MOBILE_NODE_GROUP_IDENTIFIER (Invalid group identifier
value in the request).

o The local mobility anchor MUST consider the message as a request
for extending the lifetime of all the mobility sessions that are
associated with the group identifier in the Mobile Node Group
Identifier option. However, if the Mobile Node Group Identifier
option with the sub-type value of (1) (Bulk Binding Update Group)
has an unknown group identifier, then the local mobility anchor
MUST reject the Proxy Binding Update message and send a Proxy
Binding Acknowledgement message with the Status field set to
INVALID_MOBILE_NODE_GROUP_IDENTIFIER (Invalid group identifier
value in the request).

o Upon accepting the bulk binding update request, the local mobility
anchor SHOULD extend the lifetime for all the mobility sessions
that are part of the bulk binding update group identified by the

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group identifier in the Mobile Node Group Identifier in the
message. Considerations from [RFC5213] MUST be applied for
extending the lifetime of a mobile node's session. It MUST also
send a Proxy Binding Acknowledgement message with the Status field
value set to 0 (Proxy Binding Update accepted). The lifetime
field in the message MUST be set to the allocated lifetime for all
the mobility sessions. The message MUST also include the Mobile
Node Group Identifier option, with the sub-type value of (1) (Bulk
Binding Update Group) and with the identifier value copied from
the Mobile Node Group Identifier option present in the received
Proxy Binding Update message.

o If the local mobility anchor rejects the bulk binding update
request for any administrative reason, then it MUST NOT update the
lifetime in the Binding Cache entries of any of the mobile nodes
identified by the group identifier. The local mobility anchor
SHOULD send a Proxy Binding Acknowledgement indicating the reason
for the rejection in the status code.

o Any time the local mobility anchor receives a Binding Revocation
Indication Message [RFC5846] with a Mobile Node Group Identifier
option present in the request and with the sub-type value of (1)
(Bulk Binding Update Group), the local mobility anchor MUST
consider the request as a bulk revocation request, with the
request scope including all the mobility sessions that are part of
the bulk binding update group specific to that mobile access
gateway and identified by the group identifier in Mobile Node
Group Identifier option. However, if the received request also
includes the Mobile Node Identifier option [RFC4283], the Home
Network Prefix option [RFC5213], the IPv4 Home Address Request
option [RFC5844], or the GRE Key option [RFC5845], the local
mobility anchor MUST consider this as an invalid message; it MUST
reject the Binding Revocation Indication message and send a BRA
message with the Status field set to a value of 128 (Binding Does
NOT Exist). All the considerations from [RFC5846] apply when
processing a binding revocation request, except making the scope
of the operation apply to a set of mobility sessions identified by
the group identifier present in the request.

o Upon accepting the Binding Revocation Indication request and
completing the operation, the local mobility anchor MUST send a
Binding Revocation Acknowledgement message with the Status field
set to a value of 0 (success). The message MUST include the
Mobile Node Group Identifier option, with the identifier value
copied from the Mobile Node Group Identifier option present in the
received Binding Revocation Indication message.

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RFC 6602 Bulk Binding Update Support May 2012

6. Protocol Configuration Variables

6.1. Local Mobility Anchor - Configuration Variables

This specification adds a new configuration variable for the local
mobility anchor. The configured value for this variable is expected
to survive server reboots and service restarts.

AcceptBulkBindingUpdateReqForMobilitySession

This flag indicates whether or not the local mobility anchor will
accept the request from the mobile access gateway to enable bulk
binding update support for the mobility session. The default
value for this flag is set to (1), indicating that it will accept
the request from the mobile access gateway. If the value of the
flag is set to (0), the local mobility anchor will deny the
request.

6.2. Mobile Access Gateway - Configuration Variables

This specification adds a new configuration variable for the mobile
access gateway. The configured value for this variable is expected
to survive server reboots and service restarts.

RequestBulkBindingUpdateSupportForMobilitySession

This flag indicates whether or not the mobile access gateway will
request the local mobility anchor to enable bulk binding update
support for the mobility session. The default value for this flag
is set to (1), indicating that the mobile access gateway will set
the bulk binding update flag (B) in the Proxy Binding Update
request to a value of (1). If the flag is set to a value of (0),
the mobile access gateway will set the bulk binding update flag
(B) in the Proxy Binding Update to a value of (0).

7. IANA Considerations

Per this document, IANA has done the following:

o Action-1: This specification defines a new flag (B) to the Proxy
Binding Update message, specified in [RFC5213]. This flag is
described in Section 4.1. The value of the flag (B) has been
allocated from the "Binding Update Flags" registry.

o Action-2: This specification defines a new flag (B) to the Proxy
Binding Acknowledgement message, specified in [RFC5213]. This
flag is described in Section 4.2. The value of the flag (B) has
been allocated from the "Binding Acknowledgement Flags" registry.

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RFC 6602 Bulk Binding Update Support May 2012

o Action-3: This specification defines a new Mobility Header option,
the Mobile Node Group Identifier option. This option is described
in Section 4.3. The Type value for this option has been assigned
in the same number space as allocated for the other mobility
options [RFC6275].

o Action-4: The Sub-type field of the Mobile Node Group Identifier
option introduces a new number space. This number space is now
managed by IANA, under the Registry, "Mobile Node Group Identifier
Type Registry". This specification reserves the sub-type value of
(1) (Bulk Binding Update Group). Approval of new sub-type values
are to be made through IANA Expert Review. The value range of
this field is 0 through 255, but the values 0 and 255 are marked
as reserved. The remaining values 2-254 are available for
allocation.

o Action-5: This document also defines a new status value
INVALID_MOBILE_NODE_GROUP_IDENTIFIER (Invalid group identifier
value in the request: 175) for use in the Proxy Binding
Acknowledgement message, as described in Section 4.4. This value
has been assigned from the same number space as allocated for
other status codes [RFC6275].

8. Security Considerations

The Mobile Node Group Identifier option defined in this specification
is for use in Proxy Binding Update and Proxy Binding Acknowledgement
messages. This option is carried like any other mobility header
option, and it does not require any other special security
considerations.

The bulk binding update and the bulk revocation operations specified
in this document perform operations on a group of mobility sessions.
If proper authorization checks are not in place, a malicious node may
be able to hijack a mobile node's mobility session or may carry out a
denial-of-service attack. To prevent this attack, this specification
requires the local mobility anchor to allow only authorized mobile
access gateways to perform bulk operations.

9. Acknowledgements

The authors would like to specially thank Jouni Korhonen, Basavaraj
Patil, Carlos Jesus Bernardos Cano, Dirk Von-Hugo, Pete Resnick, and
Jari Arkko for reviewing this document and providing input.

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RFC 6602 Bulk Binding Update Support May 2012

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.

[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.

[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, May 2010.

[RFC5846] Muhanna, A., Khalil, M., Gundavelli, S., Chowdhury, K.,
and P. Yegani, "Binding Revocation for IPv6 Mobility",
RFC 5846, June 2010.

[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.

10.2. Informative References

[RFC4283] Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.
Chowdhury, "Mobile Node Identifier Option for Mobile IPv6
(MIPv6)", RFC 4283, November 2005.

[RFC5845] Muhanna, A., Khalil, M., Gundavelli, S., and K. Leung,
"Generic Routing Encapsulation (GRE) Key Option for Proxy
Mobile IPv6", RFC 5845, June 2010.

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RFC 6602 Bulk Binding Update Support May 2012

Authors' Addresses

Fuad Abinader (editor)
Instituto Nokia de Tecnologia
Av. Torquato Tapajos, 7200 - Km. 12 - Col Terra Nova
Manaus, AM 69048-660
Brazil

EMail: [email protected]

Sri Gundavelli (editor)
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA

EMail: [email protected]

Kent Leung
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA

EMail: [email protected]

Suresh Krishnan
Ericsson
8400 Decarie Blvd.
Town of Mount Royal, QC
Canada

Phone: +1 514 345 7900 x42871
EMail: [email protected]

Domagoj Premec
Unaffiliated

EMail: [email protected]

Abinader, et al. Standards Track [Page 23]