One document matched: draft-ietf-mext-flow-binding-01.txt
Differences from draft-ietf-mext-flow-binding-00.txt
IETF MEXT Working Group H. Soliman, Ed.
Internet-Draft Elevate Technologies
Intended status: Standards Track N. Montavont
Expires: August 17, 2009 GET/ENST-B
N. Fikouras
K. Kuladinithi
University of Bremen
February 13, 2009
Flow Bindings in Mobile IPv6 and Nemo Basic Support
draft-ietf-mext-flow-binding-01.txt
Status of this Memo
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Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Abstract
This document introduces extensions to Mobile IPv6 and Nemo Basic
Support that allow nodes to bind one or more flows to a care-of
address. These extensions allow multihomed nodes to take full
advantage of the different properties associated with each of their
interfaces.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Mobile IPv6 Extensions . . . . . . . . . . . . . . . . . . . . 7
3.1. Flow Identification option . . . . . . . . . . . . . . . . 7
3.2. The Binding Reference Sub-option . . . . . . . . . . . . . 10
3.3. Binding Cache and Binding Update list extensions . . . . . 11
4. Protocol operations . . . . . . . . . . . . . . . . . . . . . 12
4.1. Interaction with the Multiple CoA bindings mechanism . . . 12
4.2. Flow binding storage . . . . . . . . . . . . . . . . . . . 13
4.3. Preferred Care-of address . . . . . . . . . . . . . . . . 13
4.4. Adding flow bindings . . . . . . . . . . . . . . . . . . . 13
4.5. Modifying flow bindings . . . . . . . . . . . . . . . . . 14
4.6. Removing flow bindings . . . . . . . . . . . . . . . . . . 15
4.7. Refreshing Flow Bindings . . . . . . . . . . . . . . . . . 15
4.8. Acknowledging flow identification options . . . . . . . . 15
5. Usage scenario . . . . . . . . . . . . . . . . . . . . . . . . 16
6. Mobile Node operations . . . . . . . . . . . . . . . . . . . . 18
6.1. Default Bindings . . . . . . . . . . . . . . . . . . . . . 18
6.1.1. Managing Flow Bindings with the Home Agent and MAP . . 18
6.1.2. Managing Flow Bindings in Correspondent nodes . . . . 19
6.1.3. Using Alternate Care-Of Address . . . . . . . . . . . 20
6.1.4. Receiving Binding Acknowledgements . . . . . . . . . . 20
6.2. Movement . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.3. Return Routability Procedure . . . . . . . . . . . . . . . 20
6.4. Returning Home . . . . . . . . . . . . . . . . . . . . . . 21
7. Applicability to Route Optimization . . . . . . . . . . . . . 22
7.1. Receiving Binding Udpate . . . . . . . . . . . . . . . . . 22
8. Home Agent operations . . . . . . . . . . . . . . . . . . . . 24
8.1. Receiving Binding Update with the Flow Identification
option . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.2. Sending Binding Ackowledgement . . . . . . . . . . . . . . 25
8.3. Deleting an entry in the binding cache . . . . . . . . . . 25
8.3.1. Removing Flow Bindings . . . . . . . . . . . . . . . . 26
9. Applicability to Hierarchical Mobile IPv6 . . . . . . . . . . 27
10. Security considerations . . . . . . . . . . . . . . . . . . . 28
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29
12. Informative References . . . . . . . . . . . . . . . . . . . . 30
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31
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1. Introduction
Mobile IPv6 (RFC3775) [RFC3775] and Nemo Basic Support (RFC3963)
[RFC3963] allow a mobile node / mobile router to manage its mobility
using the binding update message, which binds one care-of address to
one home address. The binding update message can be sent to the home
agent. In Mobile IPv6, the Binding Update can also be sent to
correspondent node or to a mobility anchor point (see RFC4140
[RFC4140]). The semantics of the binding update are limited to
address changes. That is, RFC3775 [RFC3775] and RFC3963 [RFC3963] do
not allow a mobile node / mobile router to bind more than one address
to the home address. Furthermore, the binding granularity is limited
to the address. Therefore, a mobile host cannot associate one of the
connections using the home address with a different care-of address.
In draft-ietf-monami6-multiplecoa Mobile IPv6 and Nemo Basic Support
are extended to allow the binding of more than one care-of address to
a home address. This specification extends Mobile IPv6 and Nemo
Basic Support to allow it to specify policies associated with each
binding. A policy can contain a request for a special treatment of a
particular flow. Hence, this specification allows a mobile node /
mobile router to bind a particular flow to a care-of address without
affecting other flows using the same home address. In addition, we
will see that this specification allows to bind a particular flow to
a particular care-of address directly with correspondent node and
mobility anchor point in the case of a single mobile node.
In this document, a flow is defined as one or more connections that
are identified by a flow identifier. A single connection is
typically identified by the source and destination IP addresses,
transport protocol number and the source and destination port
numbers. Alternatively a flow can be identified in a simpler manner
using the flow label field in the IPv6 header [RFC2460] or the
Security Parameter Index (SPI) when IPsec is used.
Flow bindings are useful in cases where the mobile node / mobile
router has more than one address, probably due to being multihomed,
and wants to direct certain flows to certain addresses. This may be
done because some flows are better suited to certain link layers or
simply to load balance flows between different interfaces. This
specification introduces the flow identifier option, which is
included in the binding update message and used to distribute
policies to the recipient of the binding update. However, this
document does not define the flow itself but only the action to take
on this flow. The flow description will be defined in another
document. This will allow to use the same flow description in
several protocols. Using the flow identifier option introduced in
this specification a mobile node / mobile router can bind one or more
flows to a care-of address while maintaining the reception of other
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flows on another care-of address. Requesting the flow binding can be
decided based on local policies within the mobile node / mobile
router and based on the link characteristics and the types of
applications running at the time. Such policies are outside the
scope of this document.
It should be noted that the flow identification option can be
associated with any binding update, whether it is sent to a
correspondent node (in the case of Mobile IPv6), home agent or
mobility anchor point (in the case of Hierarchical Mobile IPv6).
In the rest of the document, the term "mobile node" is used to
designate either a mobile node as defined in RFC3775 [RFC3775] or a
mobile router as defined in RFC3963 [RFC3963] unless stated
otherwise.
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2. Terminology
Terms used in this document are defined in [RFC3753] and
[I-D.ietf-nemo-terminology]. The following terms are also used in
this document:
Flow: A flow is identified as a set of data packets that are
exchanged between two distant hosts
Flow Description: A set of instructions that describes a flow.
Flow Identifier: Identifier of a flow binding.
Flow binding: A mobility binding extended with a flow identifier
and flow description.
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3. Mobile IPv6 Extensions
This section introduces extensions to Mobile IPv6 that are necessary
for supporting the flow binding mechanism described in this document.
3.1. Flow Identification option
The Flow identification option is included in the binding update and
acknowledgement messages. This option contains information that
allows the receiver of a binding update to install policies on a
traffic flow and route it to a given address. Multiple options may
exist within a binding update message. The Flow identification
option must come with another option (that will be defined in another
document) that will describe the flow. This additional option is
called Flow Description in the remaining of this document.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Len | PRI | FID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FID | Action | Status | PRO | Res. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow Description ...
Figure 1: The flow identification option
Option Type
TBD
Option Len
Length of option in 8-octet units
PRI
This is a 8-bit priority field to indicate the priority of a
particular option. This field is needed in cases where two
different flow descriptions in two different options overlap.
The priority field decides which policy should be in those
cases. A lower number in this field indicates a higher
priority.
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FID
The Flow Identifier field is an 8-bit unsigned integer that
includes the identifier for the flow binding. This field is
used to refer to an existing binding or to create a new
binding.
Action
This field specifies the action that needs to be taken by the
receiver of the binding update containing the flow
identification option.
Status
This field indicates the success or failure of the flow binding
operation for the particular flow in the option. This field is
not relevant to the binding update message as a whole or to
other flow identification options. Values from 0 to 127
indicate success. Values of 128 and higher indicate failure.
This field is only relevant when included in the Binding
Acknowledgement message and must be ignored in the binding
update message.
PRO
This is a 4-bit field that describes the required processing
for the option. This field may indicate a request for adding,
deleting, modifying or refreshing the option. The details of
these requests are discussed below.
Res.
This field is unused. It MUST be initialized to zero by the
sender and MUST be ignored by the receiver.
The following values are reserved for the PRO field in this option:
0 Add a flow binding
1 Replace a flow binding
2 Refresh the current binding
15 Remove a flow binding
The following values are reserved for the Action field in this
option:
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1 Forward. This value indicates a request to forward a flow to
the address included or referred by the option.
2 Discard. This value indicates a request to discard all packets
in the flow described by the option.
2 n-cast. his value indicates a request to replicate the flow to
several addresses. If this value is used, one or more Binding
Reference sub-options MUST exist. The Binding Reference sub-
option is described later in this specification
The following values are reserved for the status field within the
flow identification option:
0 Flow binding successful.
128 Flow binding rejected, reason unspecified.
129 Flow binding option poorly formed.
130 Administratively prohibited.
131 Flow identification by IPv6 prefix is not supported.
132 Flow identification by port numbers is not supported.
133 Flow identification with Flow label is not supported.
134 Flow identification with SPI is not supported.
135 FID already in use
136 FID not found
137 Classifier language not supported.
138 Discard function not supported.
139 N-cast function not supported.
It should be noted that per-packet load balancing has negative
impacts on TCP congestion avoidance mechanisms as it is desirable to
maintain order between packets belonging to the same TCP connection.
This behaviour is specified in RFC2702 [RFC2702]. Other negative
impacts are also foreseen for other types of real time connections
due to the potential variations in RTT between packets. Hence per-
packet load balancing is not allowed in this extension. However, the
MN can still request per-flow load balancing provided that the entire
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flow is moved to the new interface.
3.2. The Binding Reference Sub-option
This section introduces the Binding Reference sub-option, which may
be included in the Flow identification option. The Binding Reference
sub-option includes one or more BIDs as defined in the MCoA document.
When this sub-option is included in the Flow identification option it
associates the flow described with one or more BIDs that where
already registered with the recipient of the BU. A BID sub-option is
not necessarily included in the same BU, but MUST be already known to
the receiver of the BU. The Binding Reference sub-option is shown
below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Sub-opt Type | Sub-Opt Len | BID | ......
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ........
+-+-+-+-
Figure 2: The Binding Reference sub-option
Sub-opt Type
Indicates the Sub-option type. For the Binding Reference sub-
option, this field MUST be set to 1.
Sub-opt Len
Indicates the sub-option length in octets. This field includes
the entire length of the sub-option including the type and
length fields.
BID
The BID that the mobile node wants to associate with the flow
identification option. One or more BID fields can be included
in this sub-option.
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3.3. Binding Cache and Binding Update list extensions
Flow bindings are conceptually stored in Binding Cache of home agent,
mobility anchor point and correspondent node, and in Binding Update
List of mobile node. These logical structures need to be extended to
include the following parameters (in addition to those described in
RFC3775 [RFC3775]):
* FID (Flow Identifier). For a given home address, the FID MUST
uniquely identify an entry, i.e. a unique flow binding. An FID
is only unique for a given home address. Different mobile
nodes can use the same FID value.
* Each attribute that constitutes the flow dsecription (and that
are defined in a separate document).
An entry in these structures is identified by the couple (home
address, FID).
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4. Protocol operations
The flow identification option defines the controls on flow bindings.
The fields of the flow identification option are necessary for
indexing flow identification options, indicating the sort of action
that should be undertaken to the recipient's Binding Cache or for
carrying the results of such a petition. The flow description is
transported in another option that will be defined in another
document. This separation is made to use the same flow description
in various protocols.
This specification allows mobile nodes to direct flows to a
particular care-of address. This can be done by aggregating many
flows in the flow identification option (e.g. all TCP traffic), or by
uniquely identifying a flow in the flow identification option.
The remaining of this section discusses how mobile nodes can use the
flow identification option when sending binding updates to the
correspondent node, home agent or mobility anchor point. In
addition, deletion and modification of bindings are all discussed
below.
4.1. Interaction with the Multiple CoA bindings mechanism
Flow binding presented in this specification MUST be used with the
solution in draft-ietf-monami6-multiplecoa. The main reason why is
to avoid the duplication of the default binding to be used when none
of the registered rules can apply to a flow. As the multiple CoA
bindings document already defines a prority field which indicates
which care-of address is preferred, flow binding uses this priority
field in order to maintain a primary Care-of address (see below
section Section 4.3).
Moreover, combining the mechanism in this specification with the
multiple CoA bindings allows for further aggregation of bindings.
For example, if a mobile node has several flow identifiers bound to a
single Care-of address identified by a unique BID, the mobile node
can change the Care-of address for all these flows bindings just by
changing the Care-of address associated with the given BID.
Additionally, the combination of the two mechanisms allows for
additional features (e.g., n-casting) to take place with minimal
effort. Hence, this specification makes use of the BID option
described in draft-ietf-monami6-multiplecoa.
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4.2. Flow binding storage
Home agent, correspondent node and mobility anchor point maintain
Binding Cache in order to record associations between home addresses
and care-of addresses of mobile nodes that are away from the home
link. Mobile nodes maintain binding update list to record binding
between home address and care-of address. RFC 3775 [RFC3775] allows
mobile nodes to register only one care-of address per home address.
Thus a binding cache entry is uniquely identified by the home
address.
This specification extends the binding cache and the binding update
list structures, and allows mobile node to (1) register multiple
care-of addresses for a given home address and (2) associate flow
binding policies with the registered care-of addresses.
New parameters are added to these conceptual structures in order to
list the particular rule associated with a standard binding. On one
hand, an entry is now identified by the pair (home address, FID)
because several Care-of addresses may be bound to a single home
address. On the other hand, the Care-of address is selected
according to the best match between the packets that need to be sent,
and the existing flow bindings. If no matching is found between the
flow bindings and the data packet, a preferred entry is used (see
next subsection). If a flow matches two different flow bindings, the
PRI field indicates which action is preferred by the mobile node.
4.3. Preferred Care-of address
Any distant node which supports the flow identification option MUST
maintain a default binding per home address. A default binding
indicates an association between a home address and a Care-of
address. In addition to the default binding, several bindings may
co-exist within a binding cache for the same home address, each of
them indicating different bindings between flows and Care-of
addresses. When a data flow is intercepted by a home agent or
initiated by a correspondent node, if the said data flow does not
match an existing flow identification option, the care-of address
indicated in the default binding is used as destination address for
the mobile node. The default binding is indicated by the Priority
field in the BID option described in draft-ietf-monami6-multiplecoa.
A mobile node is responsible for having a preferred care-of address
with the receiver of the flow identification option.
4.4. Adding flow bindings
When adding a new flow binding, a mobile node sends the flow
identification option in the binding update. The care-of address
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concerned with this binding update must already be registered by the
receiver of the binding update (i.e., must already be associated with
a BID), or a BID sub-option MUST be present in the binding update (as
defined in draft-ietf-multiplecoa"). The flow identification option
MUST include a unique FID. The FID needs only be unique for the
receiver of the binding update, i.e. the same FID can be used across
different receivers of the binding update. The PRO field MUST
indicate an Add operation. Adding the flow binding implies
associating a flow with a particular care-of address for the mobile
node. The care-of address concerned with the flow binding is present
in the source address of the packet or the alternate care-of address
option. Alternatively, the care-of address may be indicated by the
BID (which is pointing to an existing care-of address) when the
Binding Reference sub-option of the Flow Identification option is
present.
The mobile node may need to define the flow partially or entirely
based on the source and destination addresses in packets. For
instance, a mobile node may choose to forward all flows from address
A to address B to a particular care-of address. Alternatively, more
granularity can be added by including port numbers and protocol.
These descriptions will be given in another document.
An Add operation implies that the FID is new and is not already used
by the mobile node for any other flow binding. If the Flow
identification option is sent without any flow description and with
the PRO field indicating an Add operation, this MUST be seen as a
wild card request by the sender. A wild card request implies that
all flows should be directed to the particular care-of address in the
packet.
4.5. Modifying flow bindings
When modifying a flow binding (either the care-of address or other
attributes of the flow), the mobile node sends the binding update
with a flow identification option. The option includes the FID for
the binding being modified, as well as the PRO field set to 1,
indicating a request to modify the binding. A flow description
option may come with the flow identification option and contain the
new attributes needed to classify the flow. Hence, flow modification
is essentially a process where an existing flow definition is removed
and a new flow (included in the option) is added and given the same
FID as the flow that was removed.
If one of the care-of addresses needs to be updated with a new one
(e.g., after a change of the IP point of attachment), the mobile node
may just need to register the new care-of address for the given BID.
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4.6. Removing flow bindings
When removing a flow binding, the mobile node sends a binding update
message with the flow identification option. The PRO field MUST be
set to a value of 15, which indicates a request for removing a flow
binding. This will provide enough information for the receiver to
locate the flow binding using the FID and remove it.
4.7. Refreshing Flow Bindings
A flow binding is refreshed by simply including the Flow
identification option in the BU message. In this case the PRO field
is set to indicate a refresh operation.
The refresh operation is included in this specification due to the
nature of the BU message. The BU message updates existing bindings
with new information. Hence, all information previously sent in the
last BU message need to be resent in all new messages, otherwise such
information will be lost.
4.8. Acknowledging flow identification options
The home agent and mobility anchor point are required to ackowledge
the reception of Binding Update by sending Binding Acknowledgment. A
correspondent node SHOULD also acknowledge Binding Update. The
Binding Acknowledgement is extended by this specification to indicate
to the mobile node the success of the flow binding. If a Binding
Acknowledgement needs to be sent in response to a Binding Update that
contained flow identification option(s), a copy of each flow
identification MUST be included. Only the Status field needs to be
changed to the appropriate value. The absence of flow identification
option in Binding Acknwoledgement indicates that the sender does not
support the extension descibed in this document and therefore MUST be
interpreted as a negative acknowledgement.
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5. Usage scenario
In this section, we highlight a use case of the flow identification
option.
Assume a mobile node equipped with two interfaces namely If1 and If2,
each connected to a different foreign network. The mobile node
configures one global IPv6 address on each interface, namely CoA1 and
CoA2 respectively. The mobile node runs Mobile IPv6 with a home
agent located in its home network. We assume that an existing IPsec
security association is set up betweeen the mobile node and its home
agent. We assume that the mobile node wants to exchange secure data
flows over CoA1 and insecure data flows over CoA2. To do so, the
mobile node may request its home agent to redirect packets intended
to the mobile node's home address to a different care-of address,
depending on the type of the communication. For example, port
numbers 22 (ssh) and 443 (https) may be tunneled to CoA1 while other
communications may be tunneled to CoA2. In order to set up these
flow bindings, the following messages are exchanged:
* The mobile node sends a Binding Update through If2, with the
source address set to CoA2. The Binding Update includes a BID
sub-option as described in draft-ietf-monami6-multiplecoa.
This sub-option intends to set the highest preference on the
given Care-of address.
* When the home agent receives the Binding Update, it first
validates the Binding Update as recommanded in section 10.3 of
[RFC3775]. If the Binding Update is accepted, the home agent
processes the BID sub-option as described in section 6.2 of
draft-ietf-monami6-multiplecoa. It then registers the source
address of the Binding Update as the preferred care-of address
for the given home address and sends back a Binding
Acknowledgement.
* Later, the mobile node sends additional Binding Update with
both Flow Identification options and BID sub-option. The BID
sub-option is used to indicate the priority of the new Care-of
address. In this example, the priority must be lower than the
priority of CoA2. The flow identification options are used to
indicate the Care-of address usage preferences. In order to
redirect source port numbers 22 and 443 to CoA1, two flow
identification options need to be transported as well in the
Binding Update. These flow identification options are set as
follows: PRI is set to 1, Action is set to 0 (forward), PRO is
set to 0 (add), FID is set to 1 (and 2 for the second option),
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and the following flow description option should indicate port
number 22 and 443.
* When the home agent receives this second Binding Update, it
first checks the validity of the Binding Update as recommanded
in section 10.3 of [RFC3775] and section 6.2 of
draft-ietf-monami6-multiplecoa. If the Binding Update is
accepted, the Flow Identification options are treated. If
these options are accepted by the home agent, it will return a
Binding Acknowledgement with Flow Identification options, each
of them having the same first 8 bytes, and the Status field set
to 0 (success).
Thereafter, if a data flow is destinated to the home address of
the mobile node, the home agent will determine if the source
port number is equal to 22 or 443. If yes, the home agent will
tunnel the data flow to CoA1. If not, the data flow will be
forwarded to CoA2.
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6. Mobile Node operations
6.1. Default Bindings
A default binding is always maintained between a MN and its peers
(home agent, correspondent node if RO is used and mobility anchor
point if applicable). The default entry indicates which care-of
address to use for a data flow that does not match any of the flow
bindings. The preferred care-of address is determined through the
BID option.
6.1.1. Managing Flow Bindings with the Home Agent and MAP
A mobile node may establish a Flow Binding by issuing a Binding
Update containing a Flow Identifier (possibly associated with a Flow
Description) in its mobility options. The Flow Identification option
MUST indicate valid FID, PRO, PRI (rule priority) and Action fields.
The PRO field of the Flow Identification option indicates the
processing that the targeted node has to perform to its Bindings
Cache List. A mobile node may request for any of the following
requests:
* 0: Add flow binding. Create a new Flow Binding with the
indicated FID and include the attached Flow. A mobile node
MUST NOT issue a Flow Identifier with the PRO field set to zero
for an existing FID.
* 1: Replace a flow binding. This request enables the mobile
node to replace attributes of the flow or the care-of address
associated with the FID. A mobile node MUST NOT issue a Flow
Identifier with the PRO field set to one for a non existent
FID.
* 2: Refresh a flow binding. This request allows the mobile node
to inform the receiver of the BU message that the flow binding
is still valid. This request does not modify the flow option.
A flow identification option MUST NOT contain this value in the
PRO field for a non-existent FID.
* 15: Remove a flow binding. This action enables a mobile node
to remove the Flow Binding indicated by the FID on the targeted
node. A mobile node MUST not issue a Flow Identifier with the
PRO field set to 15 for a non existent FID.
When adding a flow binding on the home agent or MAP, the mobile node
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MUST ensure the following:
* The PRO field MUST be set to indicate an Add operation.
* The FID field includes a value that does not already exist in
the mobile node's binding update list.
* The PRI field is set to indicate the priority of the rule in
case of an overlap between rules. An overlap can occur when
one flow matches multiple flow description options.
* If the Action field is set to indicate N-cast, the Binding
Reference sub-option must be present and it must contain one or
more BIDs. If the Binding Update sub-option includes only one
BID, it must be pointing to a care-of address other than the
one included in the binding update.
6.1.2. Managing Flow Bindings in Correspondent nodes
When route optimisation is used (see RFC3775 [RFC3775]), a mobile
node sends the BU message to the correspondent node after the return
routability test procedure. When adding flow bindings in the BU sent
to the correspondent node, the mobile node MUST ensure the following:
* The FID field includes a value that is not already stored in
the binding update list with the correspondent node's address.
* The PRO field is set to indicate an Add operation.
A mobile node can also modify or delete flow bindings in a similar
manner to that described earlier with the home agent and MAP. When
Modifying a flow binding, the mobile node MUST ensure that the FID
used already exists. The rest of the rules for modifying flow
bindings are the same as those listed above for adding a flow
binding.
Refreshing and deleting flow bindings are done in the same manner as
that described for the home agent and MAP with one exception: the
mobile node MUST NOT refresh or delete bindings associated with any
care-of address other than the one included in the BU message.
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6.1.3. Using Alternate Care-Of Address
If the Alternate Care-of Address option is used in the Binding
Update, it shall indicate the care-of address to be associated with
the Flow Identification options. The Flow Identification options
shall contain the FID to be allocated to the Flow Binding.
6.1.4. Receiving Binding Acknowledgements
According to [RFC3775] all nodes are required to silently ignore
mobility options not understood while processing Binding Updates. As
such a mobile node receiving a Binding Acknowledgement in response to
the transmission of a Binding Update MUST determine if the Binding
Acknowledgement contains a copy of the 8 bytes of every Flow
Identification options included in the Binding Update. A Binding
Acknowledgement without Flow Identification option(s) would indicate
inabillity on behalf of the source node to support the extensions
presented in this document.
If a received Binding Acknowledgement contains a copy of the 8 bytes
of each flow identification option that was sent within the Binding
Update, the status field of each flow identification option indicates
the status of the flow binding on the distant node.
6.2. Movement
When a MN changes its point of attachment to the Internet, its
Care-of address(es) may become invalid and need to be updated. All
the flow bindings that are attached to such an old Care-of address
need to be udpated with a new Care-of address. This can be achieved
by adding flow identification options in Binding Update. One flow
identification is needed per flow binding. The flow description may
not be needed if only the Care-of address is changed, and not the
filter itself. The FID must be set to the flow binding that needs to
be udpated and the PRO field MUST be set to 1 (i.e., MODIFY).
Another solution is to take advantage of the multiple care-of
addresses bindings to aggregate updates; the mobile node may only
need to update the care-of address associated with the given BID.
This would avoid to send a flow identification option per flow
binding.
6.3. Return Routability Procedure
A mobile node may perform route optimization with correpondent nodes.
Route optimization allows a mobile node to bind a care-of address to
a home address in order to allow the correspondent node to direct the
traffic to the current location of the mobile node. Before sending a
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Binding Update to correspondent node, the Return Routability
Procedure needs to be performed between the mobile node and the
correspondent node.
This procedure is not affected by the extensions defined in this
document. However, since a Binding Update message is secured with
the key generated based on the home address and care-of address test,
a mobile node MUST NOT bind a flow to a care-of address whose keygen
token (see RFC3775 [RFC3775]) was not used to generate the key for
securing the Binding Update. This limitation prohibits the sender
from requesting the n-cast action before having registered each
care-of address one by one.
6.4. Returning Home
Whenever a mobile node acquires a point of attachment to the home
network and wishes to abolish all Flow Bindings associated with the
respective home address, it is required to act as described in
Section 11.5.4 of RFC3775 [RFC3775]. This will cause the home agent
to remove all bindings that are linked to the home address, including
the flow bindings.
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7. Applicability to Route Optimization
The route optimization is only defined for mobile nodes (RFC3775
[RFC3775]), and not mobile router (RFC3963 [RFC3963]). Thus, this
section does not apply to mobile routers. This section describes the
correspondent node operations.
Every correspondent node is required to maintain a Binding Cache
containing records of associations between mobile node home addresses
and care-of addresses (bindings) as they roam away from the home
network. RFC3775 [RFC3775] allows mobile nodes to register only a
single binding per home address with each correspondent node.
This specification extends the binding cache structure, and enables
correspondent nodes to (i) maintain multiple bindings for a given
home address and (ii) to associate multiple Flow Identification /
description options with every binding, termed as Flow Binding. A
flow matching a Flow Description should be directed to the Care-of
address indicated by the Flow Binding.
7.1. Receiving Binding Udpate
When a correspondant node receives a Binding Update, it first
performs the same operation as defined in RFC3775 [RFC3775]. If the
Binding Update is valid and contains a Flow identification option,
the correspondent node needs to check the content of the PRO field.
If the PRO field contains a value indicating a request to add a new
flow binding, the following checks are done:
* The FID field includes a value that is not already stored in
the binding update list with the correspondent node's address.
* The PRO field is set to indicate an Add operation.
+ The FID field needs to contain a value that does not already
exist. If the FID contains a value that already exists, the
correspondent node MUST reject the option by sending that
option back in its Binding Acknowledgement with a Status
field that contains an error value.
+ If the Action field indicates a request to n-cast the flow,
the correspondent node MUST reject the option by sending the
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option in its binding acknowledgement with an appropriate
error code.
+ If both the FID and Action fields are valid, the
correspondent node checks the flow description that must
follow the flow identification option. If all of the checks
above indicated a valid option, the correspondent node
should add the flow binding to its binding cache.
+ The FID MUST include a value that already exists. If the
FID cannot be found in the correspondent node's binding
cache, the flow identification option MUST be rejected with
an appropriate error code.
+ If the Action field indicates a request to n-cast the flow,
the correspondent node MUST reject the option by sending the
option in its binding acknowledgement with an appropriate
error code.
+ If the Binding Reference sub-option is present, the
correspondent node MUST ensure that the BID points to the
care-of address in the packet, or to an already authrozied
care-of address. Otherwise the option MUST be rejected with
an appropriate error code.
+ If all of the above checks returned a valid result, the
correspondent node should modify the binding as requested.
If the PRO field in the option indicates a request to modify the
option, the following checks must be done by the correspondent node:
If the PRO field in the option contains a request to refresh a
binding, the correspondent node MUST ensure that the FID already
exists. If the FID does not exist, the correspondent node MUST
reject the option by sending it back in its binding acknowledgement
with an appropriate error code in the status field. Otherwise, if
the FID exists, the correspondent node must keep it in its binding
cache. No further checks need to be done in the option.
The correspondent node should reply with a Binding Acknowledgement
message. This Binding Acknowlegement message must contain a copy of
the 8 bytes of each flow identification option that was included in
the Binding Udpate. The Status field of each Flow Identification
option MUST be set to an appropriate value.
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8. Home Agent operations
This specification allows the home agent to maintain several bindings
for a given home address and to direct packets to different care-of
addresses according to flow bindings. This section details the home
agent operations necessary to implement this specification.
8.1. Receiving Binding Update with the Flow Identification option
When the home agent receives a Binding Update which includes at least
one Flow Identification option, it first performs the operation
described in section 10.3.1 of RFC3775. If the Binding Update is
accepted, the home agent then checks the flow identification option.
If the PRO field in the option indicates an Add operation, the
following checks must be done:
* The FID field needs to contain a value that does not already
exist. If the FID contains a value that already exists, the
home agent MUST reject the option by sending that option back
in its Binding acknowledgement with a Status field that
contains an appropriate error value.
* If the FID field is valid, the home agent then checks the
Action field. If the Action field contains a request for
n-cast and the Binding Reference sub-option is not included in
the option, the flow binding MUST be rejected in the binding
acknowledgement containing an error code in the Status field.
* If both of the checks above indicate valid FID and Action
fields, the home agent checks the flow description following
the flow identification option, and identifies the filter that
needs to be set up.
* If the flow option includes an action field that requests
n-casting, the home agent MUST check for the presence of the
BID sub-option(s). If the sub-options are not present, the
flow identification option MUST be rejected as a poorly
formatted option. If one or more BIDs are present in the BID
Reference sub-option, the home agent needs to create multiple
logical entries in its binding cache. All flows matching the
one in the option would be n-cast to the care-of addresses
pointed to by the BIDs or the set of registered care-of
addresses. If only one BID were included in the Binding
Reference sub-option and it pointed to a different care-of
address from the one included in the packet, then packets
matching the flow would be bicast to those two addresses.
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However, if only one BID is present and points to the same
address in the BU, the n-cast is essentially pointing to one
address and therefore cannot be performed. Such option MAY be
rejected as a poorly formatted option.
* If all of the checks above indicated a valid option, the home
agent should add the flow binding to its binding cache.
If the PRO field in the option contains a value indicating a request
to modify an existing binding, the following actions must be taken:
* The FID MUST include a value that already exists. If the FID
cannot be found in the home agent's binding cache, the flow
identification option MUST be rejected as a poorly formed
option.
* If the FID is valid, the home agent MUST perform the same steps
described above for the Add operation.
If the PRO field indicates a refresh operation, the home agent MUST
ensure that the FID in the option already exists. If the FID field
did not exist, the option MUST be rejected as a poorly formed option.
If the FID existed, the home agent MUST keep the current flow binding
in its binding cache.
8.2. Sending Binding Ackowledgement
Upon the reception of a Binding Update, the home agent is required to
send back a Binding Acknowledgment. The status code in the Binding
Acknowledgement must be set as recommanded in [RFC3775] and is not
modified by the extension defined in this specification. This status
code does not give information on the success or failure of the flow
binding.
In order to inform about the status of the flow binding that was
requested by a mobile node, a flow identification option MUST be set
in the Binding Acknowledgement message. The home agent must copy the
8 octets of each Flow Identification option received in the Binding
Update and set the status code to an approriate value. Each option
must be included in the Binding Acknowledgement message.
8.3. Deleting an entry in the binding cache
A home agent might delete an entry in its binding cache for two
reasons: either an entry expires, or the MN explicitly requests the
home agent to remove a specific entry. If an entry is going to
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expire, the home agent SHOULD send a Binding Refresh Advice.
8.3.1. Removing Flow Bindings
If the home agent receives a valid Binding Update with a flow
Identification option where the PRO field is set to 15 (Remove), the
home agent MUST remove the corresponding entry. The home agent looks
up the entry corresponding to the FID of the Binding Update. If an
entry is found, the entry is removed from the Binding cache and a
Binding Acknowledgement is sent back to the mobile node with a
success value for the status of the flow Identification option (see
section Section 8.2. This operation does not modify any other
binding that may appear with the same home address. If the FID is
not present in the binding cache entry for the corresponding home
address, the home agent MUST send back to the mobile node a Binding
Acknowledgement with error code 137 (FID not found) in the flow
identification option.
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9. Applicability to Hierarchical Mobile IPv6
This section describes the Mobility Anchor Point (MAP) operations.
The MAP operation is the same as the home agent operation. Flow
bindings sent to the MAP are associated with the regional care-of
address.
When a MAP receives a Binding Update that includes the flow
Identification option, it checks if such option is valid according to
the requirements in Section 8.1. If the option is valid, the MAP
installs the flow binding associated with the flow identified by the
flow description. The lifetime of the binding is the lifetime of the
Binding Update. Once the binding is successfully installed, the MAP
sends the binding acknowledgement and includes the flow
Identification option. The MAP sets the status field to a value
indicating success.
In all cases, a flow identification option SHOULD be included in the
Binding Acknowledgement to indicate success or failure of the flow
binding installation.
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10. Security considerations
This draft introduces a new option that adds more granularity to the
Binding Update message. The new option allows the mobile node to
associate some flows to an interface and other flows to another
interface. Since the flow Identification option is part of the
mobility header, it uses the same security as the Binding Update,
whether it is sent to the home agent, correspondent node, or MAP.
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11. Acknowledgements
We would like to thank all authors of initial I-Ds that were merged
together to create this document; in alphabetical order: C.
Castelluccia, K. ElMalki, K. Georgios, , C. Goerg, T. Noel, F.-N.
Pavlidou. Thanks to George Tsirtsis and Vince Park for their
thorough review and input to the draft. Gabor Fekete for the
analysis that led to the inclusion of the BID support. Henrik
Levkowetz for suggesting the equivalent of the CLS field to allow
other ways of describing flows.
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12. Informative References
[I-D.ietf-nemo-terminology]
Ernst, T. and H. Lach, "Network Mobility Support
Terminology", draft-ietf-nemo-terminology-06 (work in
progress), November 2006.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2702] "", 2005.
[RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, January 2005.
[RFC4140] "RF", 2005.
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Authors' Addresses
Hesham Soliman (editor)
Elevate Technologies
Email: hesham@elevatemobile.com
Nicolas Montavont
Ecole Nationale Superieure des telecommunications de Bretagne
2, rue de la chataigneraie
Cesson Sevigne 35576
France
Phone: (+33) 2 99 12 70 23
Email: nicolas.montavont@enst-bretagne.fr
URI: http://www-r2.u-strasbg.fr/~montavont/
Nikolaus A. Fikouras
University of Bremen
ComNets-ikom,University of Bremen.
Otto-Hahn-Allee NW 1
Bremen, Bremen 28359
Germany
Phone: +49-421-218-8264
Fax: +49-421-218-3601
Email: niko@comnets.uni-bremen.de
URI: http://www.comnets.uni-bremen.de
Koojana Kuladinithi
University of Bremen
ComNets-ikom,University of Bremen.
Otto-Hahn-Allee NW 1
Bremen, Bremen 28359
Germany
Phone: +49-421-218-8264
Fax: +49-421-218-3601
Email: koo@comnets.uni-bremen.de
URI: http://www.comnets.uni-bremen.de/~koo/
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