Monami6 Working Group R. Wakikawa
Internet-Draft Keio University
Intended status: Standards Track T. Ernst
Expires: September 6, 2007 INRIA
K. Nagami
INTEC NetCore
V. Devarapalli
Azaire Networks
March 5, 2007
Multiple Care-of Addresses Registration
draft-ietf-monami6-multiplecoa-02.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 6, 2007.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Wakikawa, et al. Expires September 6, 2007 [Page 1]
Internet-Draft MCoA March 2007
Abstract
According to the current Mobile IPv6 specification, a mobile node may
have several care-of addresses, but only one, termed the primary
care-of address, can be registered with its home agent and the
correspondent nodes. However, for matters of cost, bandwidth, delay,
etc, it is useful for the mobile node to get Internet access through
multiple access media simultaneously, in which case multiple active
IPv6 care-of addresses would be assigned to the mobile node. We thus
propose Mobile IPv6 extensions designed to register multiple care-of
addresses bound to a single Home Address instead of the sole primary
care-of address. For doing so, a new identification number must be
carried in each binding for the receiver to distinguish between the
bindings corresponding to the same Home Address. Those extensions
are targeted to NEMO (Network Mobility) Basic Support as well as to
Mobile IPv6.
Wakikawa, et al. Expires September 6, 2007 [Page 2]
Internet-Draft MCoA March 2007
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Multiple Care-of Addresses Registration . . . . . . . . . 7
3.2. Multiple Bindings Management . . . . . . . . . . . . . . . 7
3.3. Returning Home . . . . . . . . . . . . . . . . . . . . . . 8
4. Mobile IPv6 Extensions . . . . . . . . . . . . . . . . . . . . 10
4.1. Binding Cache Structure and Binding Update List . . . . . 10
4.2. Message Format Changes . . . . . . . . . . . . . . . . . . 10
4.2.1. Binding Unique Identifier sub-option . . . . . . . . . 10
4.2.2. Binding Acknowledgment . . . . . . . . . . . . . . . . 13
5. Mobile Node Operation . . . . . . . . . . . . . . . . . . . . 14
5.1. Management of Care-of Addresses and Binding Unique
Identifier . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2. Return Routability: Sending CoTI and Receiving CoT . . . . 14
5.3. Binding Registration . . . . . . . . . . . . . . . . . . . 15
5.4. Binding Bulk Registration . . . . . . . . . . . . . . . . 16
5.5. Binding De-Registration . . . . . . . . . . . . . . . . . 16
5.6. Returning Home . . . . . . . . . . . . . . . . . . . . . . 17
5.7. Using Alternate care-of address . . . . . . . . . . . . . 18
5.8. Receiving Binding Acknowledgment . . . . . . . . . . . . . 18
5.9. Receiving Binding Refresh Request . . . . . . . . . . . . 19
5.10. Sending Packets to Home Agent . . . . . . . . . . . . . . 20
5.11. Bootstrapping . . . . . . . . . . . . . . . . . . . . . . 20
6. Home Agent and Correspondent Node Operation . . . . . . . . . 21
6.1. Searching Binding Cache with Binding Unique Identifier . . 21
6.2. Receiving CoTI and Sending CoT . . . . . . . . . . . . . . 21
6.3. Processing Binding Update . . . . . . . . . . . . . . . . 22
6.4. Sending Binding Refresh Request . . . . . . . . . . . . . 25
6.5. Receiving Packets from Mobile Node . . . . . . . . . . . . 25
7. Network Mobility Applicability . . . . . . . . . . . . . . . . 26
8. IPsec and IKEv2 interaction . . . . . . . . . . . . . . . . . 27
8.1. Use of Care-of Address in the IKEv2 exchange . . . . . . . 27
8.2. Transport Mode IPsec protected messages . . . . . . . . . 28
8.3. Tunnel Mode IPsec protected messages . . . . . . . . . . . 28
8.3.1. Tunneled HoTi and HoT messages . . . . . . . . . . . . 28
8.3.2. Tunneled Payload Traffic . . . . . . . . . . . . . . . 29
9. Security Considerations . . . . . . . . . . . . . . . . . . . 30
Wakikawa, et al. Expires September 6, 2007 [Page 3]
Internet-Draft MCoA March 2007
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32
12.1. Normative References . . . . . . . . . . . . . . . . . . . 32
12.2. Informative References . . . . . . . . . . . . . . . . . . 33
Appendix A. Example Configurations . . . . . . . . . . . . . . . 33
Appendix B. Changes From Previous Versions . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
Intellectual Property and Copyright Statements . . . . . . . . . . 41
Wakikawa, et al. Expires September 6, 2007 [Page 4]
Internet-Draft MCoA March 2007
1. Introduction
A mobile node should use various type of network interfaces to obtain
durable and wide area network connectivity. Assumed scenarios and
motivations for multiple points of attachment, and benefits for doing
it are discussed at large in [10].
IPv6 [1] conceptually allows a node to have several addresses on a
given interface. Consequently, Mobile IPv6 [2] has mechanisms to
manage multiple ``Home Addresses'' based on home agent's managed
prefixes such as mobile prefix solicitation and mobile prefix
advertisement. But assigning a single Home Address to a node is more
advantageous than assigning multiple Home Addresses because
applications do not need to be aware of the multiplicity of Home
Addresses. If multiple home addresses are available, applications
must reset the connection information when the mobile node changes
its active network interface (i.e. change the Home Address).
According to the Mobile IPv6 specification, a mobile node is not
allowed to register multiple care-of addresses bound to a single Home
Address. Since NEMO Basic Support [3] is based on Mobile IPv6, the
same issues applies to a mobile node acting as mobile router.
Multihoming issues pertaining to mobile nodes operating Mobile IPv6
and mobile routers operating NEMO Basic Support are respectively
discussed [4] and [11] in Monami6 and NEMO Working Group.
In this document, we thus propose a new identification number called
Binding Unique Identification (BID) number for each binding cache
entry to accommodate multiple bindings registration. The BID is
assigned to either the interfaces or care-of addresses bound to a
single home address of a mobile node. The mobile node notifies the
BID to both its Home Agent and correspondent nodes by means of a
Binding Update. correspondent nodes and the home agent record the BID
into their binding cache. The Home Address thus identifies a mobile
node itself whereas the BID identifies each binding registered by a
mobile node. By using the BID, multiple bindings can then be
distinguished.
Wakikawa, et al. Expires September 6, 2007 [Page 5]
Internet-Draft MCoA March 2007
2. Terminology
Terms used in this draft are defined in [2], [5] and [6]. In
addition or in replacement of these, the following terms are defined
or redefined:
Binding Unique Identification number (BID)
The BID is an identification number used to distinguish multiple
bindings registered by the mobile node. Assignment of distinct
BID allows a mobile node to register multiple binding cache
entries for a given Home Address. The BID is generated to
register multiple bindings in the binding cache for a given
address in a way it cannot be duplicated with another BID. The
zero value and a negative value MUST NOT be used. After being
generated by the mobile node, the BID is stored in the Binding
Update List and is sent by the mobile node by means of a sub-
option of a Binding Update. A mobile node MAY change the value of
a BID at any time according to its administrative policy, for
instance to protect its privacy.
The BID is conceptually assigned to a binding. An implementation
must carefully assign the BID so as to keep using the same BID for
the same binding even when the status of the binding is changed.
More details can be found in Section 5.1.
Binding Unique Identifier sub-option
The Binding Unique Identifier sub-option is used to carry the BID.
Bulk Registration
A mobile node can register multiple bindings by sending a single
binding update. The mobile node does not necessarily put all the
available care-of addresses in the binding update, but several
care-of addresses which can be stored in a Binding Update. The
bulk registration is supported only for home registration and
deregistration as explained in Section 5.5. Note that a mobile
node should not try to perform bulk registration with
correspondent nodes.
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 [7].
Wakikawa, et al. Expires September 6, 2007 [Page 6]
Internet-Draft MCoA March 2007
3. Protocol Overview
We propose a new identification number (BID) to distinguish multiple
bindings pertaining to the same Home Address. The procedures for the
mobile node to register multiple bindings are described in the
paragraphs below.
3.1. Multiple Care-of Addresses Registration
Once a mobile node gets several IPv6 global addresses on interfaces,
it can register these addresses with its home agent (home
registration). If the mobile node wants to register multiple
bindings to its home agent, it MUST generate a BID for each care-of
address and record it into the binding update list. The mobile node
then registers its care-of addresses by sending a Binding Update with
a Binding Unique Identifier sub-option. The BID MUST be put in the
Binding Unique Identifier sub-option. After receiving the Binding
Update, the home agent verifies the request and records the binding
in its binding cache. If the newly defined sub-option is present in
the Binding Update, the home agent MUST copy the BID from the Binding
Update to the corresponding field in the binding entry. Even if
there is already an entry for the mobile node, the home agent MUST
register a new binding entry for the BID stored in the Binding Unique
Identifier sub-option. The mobile node registers multiple care-of
addresses either independently (in individual BUs) or multiple at
once (in a single BU).
If the mobile node wishes to register its binding with a
correspondent node, it must operate return routability operations.
The mobile node MUST manage a Care-of Keygen Token per care-of
address. If it is necessary (ex. Care-of Keygen token is expired),
the mobile node exchanges CoTI and CoT for the releative care-of
addresses. When the mobile node registers several care-of addresses
to a correspondent node, it uses the same BID as the one generated
for the home registration's bindings. The binding registration step
is the same as for the home registration except for calculating
authenticator by using Binding Unique Identifier sub-option as well
as the other sub-options specified in RFC 3775. For simplicity, the
bulk registration is not supported for correspondent nodes in this
document.
3.2. Multiple Bindings Management
The BID is used as a search key for a corresponding entry in the
binding cache in addition to the Home Address. When a home agent and
a correspondent node check the binding cache database for the mobile
node, it searches a corresponding binding entry with the Home Address
and BID of the desired binding. If necessary, a mobile node can use
Wakikawa, et al. Expires September 6, 2007 [Page 7]
Internet-Draft MCoA March 2007
policy and filter information to look up the best binding per
sessions, flow, packets, but this is out of scope in this document
and is currently discussed in Monami6 WG.
If there is no desired binding, it searches the binding cache
database with the Home Address as specified in Mobile IPv6. The
first matched binding entry may be found, although this is
implementation dependent.
When one of the care-of addresses has changed, the mobile node sends
a Binding Update with the new care-of address and the corresponding
BID. The receiver of the Binding Update updates the binding which
BID matches the BID contained in the received Binding Unique
Identifier sub-option. The mobile node can manage each binding
independently owing to BID.
If the mobile node decides to act as a regular mobile node compliant
with [2] , it just sends a Binding Update without a Binding Unique
Identifier sub-option (i.e. normal Binding Update). The receiver of
the Binding Update registers only a single binding for the mobile
node and, if necessary, deletes all the bindings registering with a
BID. Note that the mobile node can continue to use BID even if only
a single binding is active at some time.
3.3. Returning Home
When the mobile node returns home, there are two situations, since
the home agent defends the mobile node's Home Address by using the
proxy neighbor advertisement. It is impossible to utilize all the
interfaces when one interface is attached to the home link and the
others are attached to foreign links. If the proxy Neighbor
Advertisement for the Home Address is stopped, packets are always
routed to the interface attached to the home link. If proxy is not
stopped, packets are never routed to the interface attached to the
home link. The decision whether a mobile node returns home or not is
up to implementers.
The first situation is when a mobile node wants to return home with
interface attached to the home link. In this case, the mobile node
MUST de-register all the bindings by sending a Binding Update with
lifetime set to zero. The mobile node MAY NOT put any Binding Unique
Identifier sub-option in this packet. Then, the receiver deletes all
the bindings from its binding cache database. A home agent MUST stop
proxy neighbor advertisement for the home address of the mobile node.
The second situation is when a mobile node does not want to return
home, though one of its interfaces is attached to its home link. The
mobile node disables the interface attached to the home link and
Wakikawa, et al. Expires September 6, 2007 [Page 8]
Internet-Draft MCoA March 2007
keeps using the rest of interfaces attached to foreign links. In
this case, the mobile node sends a de-registration Binding Update for
the interface attached to the home link with the Binding Unique
Identifier sub-option. The receiver of the de-registration Binding
Update deletes only the relative binding entry from the binding cache
database. The home agent does not stop proxying neighbor
advertisement as long as there are still bindings for the other
interfaces. It is important to understand that this scenario is not
the most efficient because all the traffic from and to the mobile
node is going through the bi-directional tunnel, whereas the mobile
node is now accessible at one hop from its HA.
In the above two cases, a mobile node cannot use interfaces attached
to both home and foreign links simultaneously. If this is what a
mobile node wants, a home agent can set up another link other than
home link and uses the link for the mobile node to return virtually
to home network. Even though packets from and to the mobile node are
routed via the home agent, the hop count is kept in one. The
overhead should be negligible since it is only for an additional IPv6
header and processing tunnel (encapsulation and decapsulation) per
packets. The detail can be found in Figure 7
Wakikawa, et al. Expires September 6, 2007 [Page 9]
Internet-Draft MCoA March 2007
4. Mobile IPv6 Extensions
In this section are described the changes to Mobile IPv6 necessary to
manage multiple bindings bound to a same Home Address.
4.1. Binding Cache Structure and Binding Update List
The following additional items are required in the binding cache and
binding update list structure.
BID
The value MUST be zero if the Binding Unique identifier does not
appear in a Binding Update.
Priority of the Binding Cache Entry
A value of zero indicates No Priority. A value of 255 indicates
that the binding corresponding to this BID is a default of this
mobile node. The detail can be found in Figure 1. This
information is used by [12].
4.2. Message Format Changes
4.2.1. Binding Unique Identifier sub-option
The Binding Unique Identifier sub-option is included in the Binding
Update, Binding Acknowledgment, Binding Refresh Request, and Care-of
Test Init and Care-of Test message.
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 = TBD | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Binding Unique ID (BID) |Priority/Status|C|O| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
+ +
+ care-of address (CoA) +
+ +
+---------------------------------------------------------------+
Figure 1: BID Sub-Option
Wakikawa, et al. Expires September 6, 2007 [Page 10]
Internet-Draft MCoA March 2007
Type
Type value for Binding Unique Identifier will be assigned later.
Length
Length value MUST be 4 when C flag is unset. On the other hand if
C flag is set, Length value MUST be set to 20.
Binding Unique ID (BID)
The BID which is assigned to the binding carried in the Binding
Update with this sub-option. BID is 16-bit unsigned integer. A
value of zero is reserved.
Priority/Status
When the Binding Unique Identifier sub-option is included in a
Binding Update, this field indicates the priority field assigned
to each binding. The receiver can utilize this priority to
determine which binding is used to deliver packets. The priority
is 8-bit unsigned integer. The higher value has higher priority.
Values of zero and 255 are reserved for special meaning.
A value of zero indicates No Priority. A value of 255 indicates
that the binding corresponding to this BID is a default of this
mobile node. This default binding is used by the flow binding
scheme [12]. If the receiver cannot recognize 255, it MUST ignore
this field.
When the Binding Unique Identifier sub-option is included in a
Binding Acknowledgment, this field indicates the status
correspondent to each binding. The mobile node knows the
registration status of each binding. The status is 8-bit unsigned
integer. The possible status codes are listed below. If the
status field is below 128, it indicates that the binding
registration was successful.
MCOA ACCEPTING BID (0)
The registration of the correspond binding is successfully
operated.
MCOA REASON UNSPECIFIED (128)
Wakikawa, et al. Expires September 6, 2007 [Page 11]
Internet-Draft MCoA March 2007
Registration failed because of unknown errors
MCOA INCOMPLIANT (129)
Registration failed because Binding Unique Identifier sub-
option is not compliant.
MCOA BID CONFLICT (130)
It indicates that a regular binding (ie without the BID set) is
already registered for the home address, and is conflicting
with a received Binding Update which BID was set.
MCOA BULK REGISTRATION PROHIBITED (131)
The C flag can be set only if a Binding Unique Identifier sub-
option is presented only in a Binding Update or a Binding
Acknowledgment.
care-of address (C) flag
When this flag is set, a mobile node can store a Care-of Address
corresponding to the BID in the Binding Unique Identifier sub-
option. This flag must be used whenever a mobile node sends
multiple bindings in a single Binding Update, i.e. bulk
registration.
Overwrite (O) flag
When this flag is set, a mobile node requests a home agent to
replace all the bindings to binding entries stored in a Binding
Update. This flag is valid for Home Registration and
Deregistration.
Reserved
6 bits Reserved field. Reserved field must be set with all 0.
Care-of Address
Only when C flag is set, only a single Care-of Address matched to
the BID is stored. This field is valid only if a Binding Unique
Identifier sub-option is stored in Binding Update message.
Otherwise, this field can be omitted. The receiver SHOULD ignore
this field if the sub-option is presented in other than Binding
Update.
Wakikawa, et al. Expires September 6, 2007 [Page 12]
Internet-Draft MCoA March 2007
4.2.2. Binding Acknowledgment
The message format of Binding Acknowledgment does not change, but
operations listed below are added in this draft.
If a Binding Unique Identifier sub-option is included in a Binding
Update with the A flag set, a receiver MUST reply a Binding
Acknowledgment. The receiver node MUST include the same Binding
Unique Identifier sub-option(s) in the Binding Acknowledgment. The
receiver MUST specify relative status in the Status field of the
Binding Acknowledgment.
There are two status fields: the Status field of a Binding
Acknowledgment and the Status field of a Binding Unique Identifier
sub-option. In this specification, the Status field of a Binding
Acknowledgment indicates the registration status of a "Binding
Update". The status value in the Binding Acknowledgment is for all
Binding Unique Identifier sub-options stored in the Binding
Acknowledgment. For example, if the status value is 134 in the
status field of the Binding Acknowledgment, all the care-of addresses
stored in the Binding Unique Identifier sub-options are rejected
because the duplicate address detection has failed on the home agent.
The status field of the Binding Unique Identifier sub-option only
informs the receiver about the binding relative to the sub-option.
Whether each Care-of address has been successfully registered
successfully or not is given in the Status field of each Binding
Unique Identifier sub-option.
New status values for the status field of a Binding Acknowledgment
are defined for handling the multiple Care-of Addresses registration:
MCOA PROHIBITED(TBD)
It implies the multiple care-of address registration is
administratively prohibited.
MCOA BULK REGISTRATION NOT SUPPORTED (TBD)
The bulk binding registration is not supported.
MCOA FLAG CONFLICTS (TBD)
The flags of the sub-options presented in a Binding Update
conflicts.
Wakikawa, et al. Expires September 6, 2007 [Page 13]
Internet-Draft MCoA March 2007
5. Mobile Node Operation
5.1. Management of Care-of Addresses and Binding Unique Identifier
There are two cases when a mobile node has several Care-of Addresses:
1. A mobile node uses several physical network interfaces and
acquires a care-of address on each of its interfaces.
2. A mobile node uses a single physical network interface, but
multiple prefixes are announced on the link the interface is
attached to. Several global addresses are configured on this
interface for each of the announced prefixes.
The difference between the above two cases is only a number of
physical network interfaces and therefore does not matter in this
document. The Identification number is used to identify a binding.
To implement this, a mobile node MAY assign an identification number
for each care-of addresses. How to assign an identification number
is up to implementers.
A mobile node assigns a BID to each care-of address when it wants to
register them simultaneously with its Home Address . The value
should be generated from a value comprised between 1 to 65535. Zero
and negative values MUST NOT be taken as a BID. If a mobile node has
only one care-of address, the assignment of a BID is not needed until
it has multiple care-of addresses to register with.
5.2. Return Routability: Sending CoTI and Receiving CoT
When a mobile node wants to register bindings to a Correspondent
Node, it MUST send a CoTI per care-of address, while the HoTI and HoT
can be exchanged only once for a Home Address. If the Mobile Node
manages bindings with BID, it MUST include a Binding Unique
Identifier sub-option in a Care-of Test Init message. It MUST NOT
set the C and O flag in the sub-option.
The receiver (i.e. correspondent node) will calculate a care-of
keygen token with the received BID and reply a Care-of Test message
which contains a Binding Unique Identifier sub-option as described in
Section 6.2. When the mobile node receives the Care-of Test message,
the Care-of Test message is verified as same as in [2] and the
Binding Unique Identifier sub-option in the Care-of Test MUST be
processed as follows:
o If a Binding Unique Identifier sub-option is not presented in CoT
in reply to the CoTI containing the Binding Unique Identifier sub-
option, a correspondent node does not support the Multiple Care-of
Wakikawa, et al. Expires September 6, 2007 [Page 14]
Internet-Draft MCoA March 2007
Address registration. Thus, the mobile node MUST NOT use a
Binding Unique Identifier sub-option in the Binding Update. It
MUST send a regular Binding Update (i.e. no BID) to the
correspondent node [2]. The Mobile Node MAY skip resending
regular CoTI message and use the received care-of keygen token for
the regular Binding Update, because the correspondent node just
ignores and skip the Binding Unique Identifier sub-option and
calculates the care-of keygen token as [2] specified.
o If the status field of a Binding Unique Identifier sub-option is
set to [MCOA BULK REGISTRATION PROHIBITED], the care-of keygen
token MUST NOT be used for a Binding Update. It MUST re-send a
Care-of Test Init message again with a corrected Binding Unique
Identifier sub-option (i.e. C flag MUST be unset).
o If the status field is set to less than 128, it sends a Binding
Update through Return Routability procedure.
The computation of MAC is the same as the one in [2] except for
calculation of a care-of keygen token. The calculation of a care-of
keygen token is modified as follows. BID is used to generate the
care-of keygen token.
care-of keygen token := First (64, HMAC_SHA1 (Kcn, (care-of address |
nonce | BID | 1)))
5.3. Binding Registration
When a mobile node sends a Binding Update, it MUST decide whether it
registers multiple care-of addresses or not. However, this decision
is out-of scope in this document. If a mobile node decides not to
register multiple care-of addresses, it completely follows the
standard RFC 3775 specification.
If a mobile node needs to register multiple Care-of Addresses, it
MUST use BID to identify a care-of address. The mobile node includes
a Binding Unique Identifier sub-option in the Mobility Option field
of a Binding Update. The BID is copied from a corresponding Binding
Update List entry to the BID field of the Binding Unique Identifier
sub-option. If the mobile node wants to replace existing registered
bindings on the home agent to the binding entry(s) in the Binding
Update, it can set O flag.
If a mobile node registers bindings to a correspondent node, it MUST
have both active home and care-of keygen tokens for Kbm (see Section
5.2.5 of [2]. The care-of keygen tokens MUST be maintained for each
care-of address that the mobile node wants to register to the
correspondent node, as described in Section 5.2. After computing an
Wakikawa, et al. Expires September 6, 2007 [Page 15]
Internet-Draft MCoA March 2007
Authenticator value, it sends a Binding Update which contains a
Binding Unique Identifier sub-option. The Binding Update is
protected by a Binding Authorization Data sub-option placed after the
Binding Unique Identifier sub-option. The Mobile Node MUST NOT set
the C flag in the Binding Unique Identifier sub-option.
5.4. Binding Bulk Registration
The bulk registration is an optimization for registering multiple
care-of addresses only to a home agent by using a single Binding
Update. If a mobile node, for instance, does not want to send a lot
of control messages through an interface which bandwidth is scarce,
it can use this bulk registration and send a Binding Update
containing multiple or all the valid care-of addresses from a
specific interface which has wider bandwidth.
In this case, a mobile node sets the C flag in a Binding Unique
Identifier sub-option and stores the particular care-of address in
the Binding Unique Identifier sub-option. When the C flag is set,
the length field of the suboption MUST be set to 20. The mobile node
can store multiple sets of a Binding Unique Identifier sub-option in
a Binding Update. If the mobile node wants to replace existing
registered bindings on the home agent with the bindings in the sent
Binding Update, it can set O flag. Section 6.3 describes this
registration procedure in detail. In the bulk registration, all the
other binding information such as Lifetime, Sequence Number, binding
Flags are shared among the bulked Care-of Addresses. Whether a
mobile node registers multiple Care-of Addresses separately or in
bulk is up to implementations.
In the bulk registration, the Sequence Number field of a Binding
Update SHOULD be carefully configured. If each binding uses
different sequence number, a mobile node MUST use the largest
sequence number from the binding update list used for the bulk
registration. If it cannot select a sequence number for all the
bindings due to sequence number out of window, it MUST NOT use the
bulk registration for the binding which sequence number is out of
window and uses a separate Binding Update for the binding.
When multiple Binding Unique Identifier sub-options are presented,
the flag field of all the sub-options MUST have the same value. For
example, if C flag is set, the same flag MUST be set to all the sub-
options.
5.5. Binding De-Registration
When a mobile node decides to delete all the bindings for its home
address, it sends a regular de-registration Binding Update. A
Wakikawa, et al. Expires September 6, 2007 [Page 16]
Internet-Draft MCoA March 2007
Binding Unique Identifier sub-option is not required. See
Section 6.3 for details.
If a mobile node wants to delete a particular binding from its home
agent and correspondent nodes (e.g. from foreign link), the mobile
node simply sets zero lifetime or uses the home address as the source
address in a Binding Update. The Binding Update MUST contain a
relative Binding Unique Identifier Sub-option (C flag MUST NOT be
set). The receiver will remove only the care-of address that matches
the specified BID.
On the other hand, when a mobile node decides to return home (ie only
uses its interface attached to the home link), it MUST de-register
all the registered bindings. To do so, the mobile node stores
multiple Binding Unique Identifier sub-options in a Binding Update
which lifetime is set to zero or which source address is set to the
Home Address. C flag MUST be specified in all the Binding Unique
Identifier sub-options. The care-of addresses field of each sub-
option MAY be omitted, because the receiver will remove all the
care-of addresses which matches the specified BID.
O flag is always ignored if a Binding Update is for binding de-
registration
5.6. Returning Home
When a mobile node returns home, it MUST de-register all bindings
with the home agent.
Although the mobile node SHOULD delete the bindings with
Correspondent Nodes as well, the node MAY still keep the binding of
the other interface active attached to foreign links only at the
Correspondent Nodes. In such case, the mobile node still receives
packets at the other interface attached to a foreign link thanks to
route optimization. The mobile node also receives packets at the
interface attached to the home link when correspondent nodes does not
use route optimization.
Note that when the mobile node does not want to return home even if
one of interfaces is attached to the home link, the mobile node MUST
disable the interface. Otherwise, address duplication will be
observed because the home agent still defend the Home Address by the
proxy neighbor advertisement and the mobile node also enables the
same Home Address on the home link. After disabling the interface
attached to the home link, the mobile node MUST delete the binding
for the interface by sending a de-registration binding update. The
de-registration binding update must be sent from one of active
interfaces attached to foreign links. As a result, the mobile node
Wakikawa, et al. Expires September 6, 2007 [Page 17]
Internet-Draft MCoA March 2007
no longer receives packets at the interface attached to the home
link. All packets are routed to other interfaces attached to a
foreign link.
5.7. Using Alternate care-of address
A mobile node can use an alternate care-of address in a following
situation. One care-of address becomes invalid (e.g because the link
where it is attached to is no longer available) and MUST be deleted.
In such case, the mobile node can not send a Binding Update from the
care-of address because the interface's link is lost. The mobile
node needs to de-register the remote binding of the care-of address
through one of its active care-of addresses.
In this case, the mobile node include both Alternate Care-of Address
sub-option and Binding Unique Identifier sub-option in a Binding
Update. An Alternate care-of address sub-option can be presented
only once in a Binding Update after a Binding Unique Identifier sub-
option. The care-of address stored in an Alternate Care-of address
sub-option is replaced the address in the source address field as
same as [2] specified.
If C flag is set in a Binding Unique Identifier sub-option, an
Alternate Care-of Address sub-option SHOULD NOT be used. A receiver
uses the care-of addresses and BID stored in each Binding Unique
Identifier sub-option to modify corresponding binding cache entries.
Any address can be specified in the Source address field of the IPv6
header of the Binding Update even without an Alternate Care-of
Address sub-option.
5.8. Receiving Binding Acknowledgment
The verification of a Binding Acknowledgment is the same as in Mobile
IPv6 (section 11.7.3 of RFC 3775). The operation for sending a
Binding Acknowledgment is described in Section 6.3.
If a mobile node includes a Binding Unique Identifier sub-option in a
Binding Update with A flag set, a Binding Acknowledgment MUST have a
Binding Unique Identifier sub-option in the Mobility Options field.
If no such sub-option appears in the Binding Acknowledgment replied
to the Binding Update for the multiple care-of address registration,
this means that the originator node of this Binding Acknowledgment
might not recognize the Binding Unique Identifier sub-option. The
mobile node SHOULD stop registering multiple care-of addresses by
using a Binding Unique Identifier sub-option. If the originator is
the home agent, the mobile node MAY try to discover a new home agent
supporting the multiple care-of address registration or give up with
the multiple care-of address registration.
Wakikawa, et al. Expires September 6, 2007 [Page 18]
Internet-Draft MCoA March 2007
If a Binding Unique Identifier sub-option is present in the received
Binding Acknowledgment, the mobile node checks the Status field of
the Binding Acknowledgment. If the status code indicates successful
registration (less than 128), the originator successfully registered
the binding information and BID for the mobile node.
If the status code of the Binding Acknowledgment is greater than or
equal to 128, the mobile node proceeds with relevant operations
according to the status code of the Binding Acknowledgment. The
status value of the stored Binding Unique Identifier sub-option may
be used to decide further operation.
o If the Status value of the Binding Acknowledgment is [MCOA
PROHIBITED], the mobile node MUST give up registering multiple
bindings to the peer sending the Binding Acknowledgment. It MUST
return to the regular Mobile IPv6 [2] for the peer node.
o If the Status value is [MCOA BULK REGISTRATION NOT SUPPORT], the
mobile node SHOULD stop using bulk registration to the peer
sending the Binding Acknowledgment.
o If [MCOA FLAG CONFLICTS] is specified in the Binding
Acknowledgment, it indicates that the different flag values are
used in Binding Unique Identifier sub-options in a Binding Update.
If the C flag is set, all sub-options MUST have C flag. It is
same for O flag. How to handle other error status codes is
specified in [2].
The mobile node also learn detailed registration status from the
Status field of each Binding Unique Identifier sub-option. If the
value is greater than or equal to 128, the mobile node proceeds with
relevant operations according to the status value.
o If [MCOA BID CONFLICT] is specified, the binding entry specified
by the Binding Unique Identifier sub-option is already registered
as a regular binding. In such case, the mobile node SHOULD stop
sending Binding Updates with BID, or SHOULD use O flag for the
peer sending the Binding Acknowledgment.
5.9. Receiving Binding Refresh Request
The verification of a Binding Refresh Request is the same as in
Mobile IPv6 (section 11.7.4 of RFC 3775). The operation of sending a
Binding Refresh Request is described in section Section 6.4.
If a mobile node receives a Binding Refresh Request with a Binding
Unique Identifier sub-option, this Binding Refresh Request requests a
binding indicated by the BID. The mobile node SHOULD update only the
Wakikawa, et al. Expires September 6, 2007 [Page 19]
Internet-Draft MCoA March 2007
respective binding. The mobile node MUST put a Binding Unique
Identifier sub-option into the Binding Update sent to refresh the
entry.
If no Binding Unique Identifier sub-option is present in a Binding
Refresh Request, the mobile node sends a Binding Update according to
its Binding Update List for the requesting node. On the other hand,
if the mobile node does not have any Binding Update List entry for
the requesting node, the mobile node needs to register either a
single binding or multiple bindings depending on its binding
management policy.
5.10. Sending Packets to Home Agent
When a multihomed mobile node sends packets to its home agent, there
are conceptually two ways to construct packets.
1. Using Home Address Option. (required additional 24 bytes)
2. Using IPv6-IPv6 tunnel. (required additional 40 bytes)
Beside the additional size of packets, no difference is observed
between these two. The routing path is always the same and no
redundant path such as dog-leg route or triangular route occurs.
However, in this document, the mobile node is capable of using
multiple care-of addresses for outgoing packets. This is problem in
home agent side because they must verify the Care-of address for all
the packets received from the mobile node. Therefore, the mobile
node SHOULD use the bi-directional tunnel even if it registers a
binding(s) to the home agent. When it uses the Home Address option,
the home agent MAY reject the packets because the Care-of address in
the packet and the first found Care-of Address in the binding Cache
of the home agent are different. The mobile node then receive
Binding Error for the packet drop.
5.11. Bootstrapping
When a mobile node bootstraps and registers multiple bindings at the
first time, it SHOULD set O flag in the Binding Unique Identifier
sub-option. when old bindings still exists at the Home Agent and
Correspondent Nodes, the mobile node has no way to verify which
bindings are left as a garbage in those nodes. This scenario happens
when a mobile node reboots without correct deregistration. If O flag
is used, all the bindings are replaced to the new binding(s). Thus,
the garbage bindings are surely removed by the first Binding Update.
XXX SEQ
Wakikawa, et al. Expires September 6, 2007 [Page 20]
Internet-Draft MCoA March 2007
6. Home Agent and Correspondent Node Operation
6.1. Searching Binding Cache with Binding Unique Identifier
If either a correspondent node or a home agent has multiple bindings
for a mobile node in their binding cache database, it can use any of
the bindings to communicate with the mobile node. How to select the
most suitable binding from the binding cache database is out of scope
in this document.
Whenever a correspondent node searches a binding cache for a home
address, it SHOULD uses both the Home Address and the BID as the
search key if it knows the corresponding BID. If the priority is
available for a binding cache entry, the priority can be used as
additional key to search a binding. In the example below, if a
correspondent node searches the binding with the Home Address and
BID2, it gets binding2 for this mobile node.
binding1 [a:b:c:d::EUI, care-of address1, BID1]
binding2 [a:b:c:d::EUI, care-of address2, BID2]
binding3 [a:b:c:d::EUI, care-of address3, BID3]
Figure 2: Searching the Binding Cache
A correspondent node basically learns the BID when it receives a
Binding Unique Identifier sub-option. At the time, the correspondent
node MUST look up its binding cache database with the Home Address
and the BID retrieved from the Binding Update. If the correspondent
node does not know the BID, it searches for a binding with only a
Home Address as performed in Mobile IPv6. In such case, the first
matched binding is found. But which binding entry is returned for
the normal search depends on implementations. If the correspondent
node does not desire to use multiple bindings for a mobile node, it
can simply ignore the BID.
6.2. Receiving CoTI and Sending CoT
When a correspondent node receives a Care-of Test Init message which
contains a Binding Unique Identifier sub-option, it MUST process it
with following steps.
First of all, the Care-of Test Init message is verified according to
[2]. The Binding Unique Identifier sub-option MUST be processed as
follows:
Wakikawa, et al. Expires September 6, 2007 [Page 21]
Internet-Draft MCoA March 2007
o If a correspondent node does not understand a Binding Unique
Identifier sub-option, it will ignore and skip this option. The
calculation of a care-of keygen token will thus be done without a
BID value. After regular processing of HoTI message according to
[2], it will return a Care-of Test message without use of a
Binding Unique Identifier sub-option. The mobile node can thus
know whether its correspondent can process or not the Binding
Unique Identifier sub-option by checking if such option is present
in the Care-of Test message.
o If C flag is set in the sub-option, the Correspondent Node SHOULD
NOT calculate a care-of keygen token and MUST include a Binding
Unique Identifier sub-option which status value set to [MCOA BULK
REGISTRATION PROHIBITED] in the returned Care-of Test message.
All the fields of the Care-of Test message MUST be set to zero.
All the Binding Unique Identifier sub-options SHOULD be copied
from the received one except for the Status Field and the Care-of
Address field.
o If O flag is set in the sub-option, the Correspondent Node can
ignore this flag and can process it as described in the next
bullet.
o Otherwise, the correspondent node MUST include a Binding Unique
Identifier sub-option which status value MUST be set to [MCOA
ACCEPTING BID] in the returning a Care-of Test message. The
Binding Unique Identifier sub-option SHOULD be copied from the
received one except for the Status Field and the Care-of address
Field.
The calculation of a care-of keygen token is modified as follows.
The BID is used to generate the care-of keygen token.
care-of keygen token := First (64, HMAC_SHA1 (Kcn, (care-of address |
nonce | BID | 1)))
6.3. Processing Binding Update
If a Binding Update does not contain a Binding Unique Identifier sub-
option, its processing is same as in RFC 3775. But if the receiver
already has multiple bindings for the Home Address, it MUST replace
all existing bindings by the received binding. As a result, the
receiver node MUST have only a binding for the mobile node. If the
Binding Update is for de-registration, the receiver MUST delete all
existing bindings from its Binding Cache.
On the other hand, if a Binding Update contains a Binding Unique
Identifier sub-option(s), the Binding Update is also validated
Wakikawa, et al. Expires September 6, 2007 [Page 22]
Internet-Draft MCoA March 2007
according to section 9.5.1 of [2] and the following step.
o If the home flag is set in the Binding Update, the home agent MUST
carefully operate DAD for the received Home Address. If the home
agent has already had a binding(s) for the Mobile Node, it MUST
avoid running DAD when it receives the Binding Update.
If a Binding Unique Identifier sub-option(s) is present, the receiver
node MUST process the sub-option.
o The length value is examined. The length value MUST be either 4
or 20 depending on C flag. If the length is incorrect, the
receiver MUST rejects the Binding Update and returns all the
received Binding Unique Identifier sub-option which status value
is set to [MCOA INCOMPLIANT]. The status field of the Binding
Acknowledgment MUST be set to [REASON UNSPECIFIED, 128].
o When C flag is set, the receiver MUST support the bulk
registration. Otherwise, it MUST reject the Binding Update and
returns all the received Binding Unique Identifier sub-option
which status value is set to [MCOA REASON UNSPECIFIED]. The
status field of the Binding Acknowledgment MUST be set to [MCOA
BULK REGISTRATION NOT SUPPORTED].
o When either C or O flag is set, the flags field of all the Binding
Unique Identifier sub-option stored in the same Binding Update
MUST be equal. Otherwise, the receiver MUST reject the Binding
Update and returns all the received Binding Unique Identifier sub-
option which status value is set to [MCOA REASON UNSPECIFIED].
The status field of the Binding Acknowledgment MUST be set to
[MCOA FLAG CONFLICTS].
o When C flag is specified, the care-of address MUST be given in the
Binding Unique Identifier sub-option. Otherwise, the receiver
MUST reject the Binding Update and returns all the received
Binding Unique Identifier sub-option which status value is set to
[MCOA INCOMPLIANT]. The status field of the Binding
Acknowledgment MUST be set to [REASON UNSPECIFIED, 128].
o If the Lifetime field of the Binding Update is zero, the receiver
node deletes the binding entry which BID is same as BID sent by
the Binding Unique Identifier sub-option. If the receiver node
does not have appropriate binding which BID is matched with the
Binding Update, it MUST reject this de-registration Binding
Update. If the receiver is a Home Agent, it SHOULD also return a
Binding Acknowledgment to the mobile node, in which the Status
field is set to [not Home Agent for this mobile node, 133]. If O
flag is set in the deregistering Binding Update, the receiver can
Wakikawa, et al. Expires September 6, 2007 [Page 23]
Internet-Draft MCoA March 2007
ignore this flag for deregistration.
o If the Lifetime field is not zero, the receiver node registers a
binding with the specified BID as a mobile node's binding. The
Care-of address is picked from the Binding Update packet as
follows:
* If C flag is set in the Binding Unique Identifier sub-option,
the care-of address must be taken from the care-of address
field in each Binding Unique Identifier sub-option.
* If C flag is not set in the Binding Unique Identifier sub-
option, the care-of address must be taken from the Source
Address field of the IPv6 header.
* If C flag is not set and an alternate care-of address is
present, the care-of address is taken from the Alternate
Care-of address sub-option.
o Once the care-of address(es) has been retrieved from the Binding
Update, it starts registering binding(s).
* Only if O flag is set in the sub-option, the home agent first
removes all the existing bindings and registers the received
bindings.
* If the receiver has a regular binding which does not have BID
for the mobile node, it de-registers the regular binding and
registers a new binding including BID according to the Binding
Update. In this case, the receiver MUST specify [MCOA BID
CONFLICT] to the Binding Unique Identifier sub-option which is
replied to the Mobile Node. The Status field of the replying
Binding Acknowledgment MUST be set to [Binding Update ACCEPTED,
0].
* If the receiver node has already registered the binding which
BID is matched with requesting BID, then it MUST update the
binding with the Binding Update.
* If the receiver does not have a binding entry which BID is
matched with the requesting BID, it registers a new binding for
the BID.
If all the above operations are successfully finished, the Binding
Acknowledgment containing the Binding Unique Identifier sub-options
MUST be replied to the mobile node if A flag is set in the Binding
Acknowledgment. Whenever a Binding Acknowledgment is returned, all
the Binding Unique Identifier sub-options stored in the Binding
Wakikawa, et al. Expires September 6, 2007 [Page 24]
Internet-Draft MCoA March 2007
Update MUST be copied to the Binding Acknowledgment. The Care-of
address field of each Binding Unique Identifier sub-option, however,
can be omitted, because the mobile node can match a corresponding
binding update list by using BID.
6.4. Sending Binding Refresh Request
When either a correspondent node or home agent notices that a
registered binding will be expired soon, it MAY send a Binding
Refresh Request. If the registered binding has BID, the
correspondent node SHOULD contain a Binding Unique Identifier sub-
option in the Binding Refresh Request. Then, the Correspondent Node
can receive a Binding Update with a Binding Unique Identifier sub-
option and can update only the particular binding. If the registered
binding does not have BID, then the correspondent node sends a
Binding Refresh Request without the sub-option.
6.5. Receiving Packets from Mobile Node
When a correspondent node receives packets with a Home Address
destination option from a mobile node, it MUST check that the care-of
address appeared in the Source Address field MUST be equal to one of
the care-of addresses in the binding cache entry. If no binding is
found, the packets MUST be silently discarded and MUST send a Binding
Error message according to RFC3775. This verification MUST NOT be
done for a Binding Update.
Wakikawa, et al. Expires September 6, 2007 [Page 25]
Internet-Draft MCoA March 2007
7. Network Mobility Applicability
Support of multihomed mobile routers is advocated in the NEMO working
group (see R12 "The solution MUST function for multihomed MR and
multihomed mobile networks" in [8].
Issues regarding mobile routers with multiple interfaces and other
multihoming configurations are documented in [11].
Since the binding management mechanisms are the same for a mobile
host operating Mobile IPv6 and for a mobile router operating NEMO
Basic Support (RFC 3963), our extensions can also be used to deal
with multiple care-of addresses registration sent from a multihomed
mobile router.
Wakikawa, et al. Expires September 6, 2007 [Page 26]
Internet-Draft MCoA March 2007
8. IPsec and IKEv2 interaction
Mobile IPv6 [2] and the NEMO protocol [3] require the use of IPsec to
protect signaling messages like Binding Updates, Binding
Acknowledgments and return routability messages. IPsec may also be
used protect all reverse tunneled data traffic. The Mobile IPv6-
IKEv2 specification [9] specifies how IKEv2 can be used to setup the
required IPsec security associations. The following assumptions were
made in RFC 3775, RFC 3963 and the MIP6-IKEv2 specification with
respect to the use of IKEv2 and IPsec.
o There is only one primary care-of address per mobile node.
o The primary care-of address is stored in the IPsec database for
tunnel encapsulation and decapsulation.
o When the home agent receives a packet from the mobile node, the
source address is verified against the care-of address in the
corresponding binding cache entry. If the packet is a reverse
tunneled packet from the mobile node, the care-of address check is
done against the source address on the outer IPv6 header. The
reverse tunnel packet could either be a tunneled HoTi message or
tunneled data traffic to the correspondent node.
o The mobile node runs IKEv2 (or IKEv1) with the home agent using
the care-of address. The IKE SA is based on the care-of address
of the mobile node.
The above assumptions may not be valid when multiple care-of
addresses are used by the mobile node. In the following sections,
the main issues with the use of multiple care-of address with IPsec
are addressed.
8.1. Use of Care-of Address in the IKEv2 exchange
For each home address the mobile node sets up security associations
with the home agent, the mobile node must pick one care-of address
and use that as the source address for all IKEv2 messages exchanged
to create and maintain the IPsec security associations associated
with the home address. The resultant IKEv2 security association is
created based on this care-of address.
If the mobile node needs to change the care-of address, it just sends
a Binding Update with the care-of address it wants to use, with the
corresponding Binding Unique Identifier sub-option, and with the 'K'
bit set. This will force the home agent to update the IKEv2 security
association to use the new care-of address. If the 'K' bit is not
supported on the mobile node or the home agent, the mobile node MUST
Wakikawa, et al. Expires September 6, 2007 [Page 27]
Internet-Draft MCoA March 2007
re-establish the IKEv2 security association with the new care-of
address. This will also result in new IPsec security associations
being setup for the home address.
8.2. Transport Mode IPsec protected messages
For Mobile IPv6 signaling message protected using IPsec in transport
mode, the use of a particular care-of address among multiple care-of
addresses does not matter for IPsec processing.
For Mobile Prefix Discovery messages, RFC 3775 requires the home
agent to verify that the mobile node is using the care-of address
that is in the binding cache entry that corresponds to the mobile
node's home address. If a different address is used as the source
address, the message is silently dropped by the home agent. This
document requires the home agent implementation to process the
message as long as the source address is is one of the care-of
addresses in the binding cache entry for the mobile node.
8.3. Tunnel Mode IPsec protected messages
The use of IPsec in tunnel mode with multiple care-of address
introduces a few issues that require changes to how the mobile node
and the home agent send and receive tunneled traffic. The route
optimization mechanism described in RFC 3775 mandates the use of
IPsec protection in tunnel mode for the HoTi and HoT messages. The
mobile node and the home agent may also choose to protect all reverse
tunneled payload traffic with IPsec in tunnel mode. The following
sections address multiple care-of address support for these two types
of messages.
8.3.1. Tunneled HoTi and HoT messages
The mobile node MAY use the same care-of address for all HoTi
messages sent reverse tunneled through the home agent. The mobile
node may use the same care-of address irrespective of which
correspondent node the HoTi message is being sent. RFC 3775 requires
the home agent to verify that the mobile node is using the care-of
address that is in the binding cache entry, when it receives a
reverse tunneled HoTi message. If a different address is used as the
source address, the message is silently dropped by the home agent.
This document requires the home agent implementation to decapsulate
and forward the HoTi message as long as the source address is one of
the care-of addresses in the binding cache entry for the mobile node.
When the home agent tunnels a HoT message to the mobile node, the
care-of address used in the outer IPv6 header is not relevant to the
HoT message. So regular IPsec tunnel encapsulation with the care-of
Wakikawa, et al. Expires September 6, 2007 [Page 28]
Internet-Draft MCoA March 2007
address known to the IPsec implementation on the home agent is
sufficient.
8.3.2. Tunneled Payload Traffic
When the mobile sends and receives multiple traffic flows protected
by IPsec to different care-of addresses, the use of the correct
care-of address for each flow becomes important. Support for this
requires the following two considerations on the home agent.
o When the home agent receives a reverse tunneled payload message
protected by IPsec in tunnel mode, it must check that the care-of
address is one of the care-of addresses in the binding cache
entry. According to RFC 4306, the IPsec implementation on the
home agent does not check the source address on the outer IPv6
header. Therefore the care-of address used in the reverse
tunneled traffic can be different from the care-of address used as
the source address in the IKEv2 exchange. However, the Mobile
IPv6 stack on the home agent MUST verify that the source address
is one of the care-of addresses registered by the mobile node
before decapsulating and forwarding the payload traffic towards
the correspondent node.
o For tunneled IPsec traffic from the home agent to the mobile node,
The IPsec implementation on the home agent may not be aware of
which care-of address to use when performing IPsec tunnel
encapsulation. The Mobile IP stack on the home agent must specify
the tunnel end point for the IPsec tunnel. This may require tight
integration between the IPsec and Mobile IP implementations on the
home agent.
Wakikawa, et al. Expires September 6, 2007 [Page 29]
Internet-Draft MCoA March 2007
9. Security Considerations
TBD
Wakikawa, et al. Expires September 6, 2007 [Page 30]
Internet-Draft MCoA March 2007
10. IANA Considerations
TBD
Wakikawa, et al. Expires September 6, 2007 [Page 31]
Internet-Draft MCoA March 2007
11. Acknowledgments
The authors would like to thank Masafumi Aramoto (Sharp Corporation),
Julien Charbon, Tero Kauppinen (Ericsson), Susumu Koshiba, Martti
Kuparinen (Ericsson), Romain Kuntz (Keio-U), Heikki Mahkonen
(Ericsson), Hiroki Matutani (Tokyo-U), Koshiro Mitsuya (Keio-U),
Nicolas Montavont, Koji Okada (Keio-U), Keisuke Uehara (Keio-U),
Masafumi Watari (KDDI R&D) in alphabetical order, the Jun Murai Lab.
at KEIO University, and WIDE project for their contributions.
12. References
12.1. Normative References
[1] Deering, S. and R. Hinden, "Internet Protocol Version 6
(IPv6)", IETF RFC 2460, December 1998.
[2] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004.
[3] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005.
[4] Montavont, N., Wakikawa, R., Ernst, T., Ng, C., and K.
Kuladinithi, "Analysis of Multihoming in Mobile IPv6",
draft-ietf-monami6-mipv6-analysis-02 (work in progress),
February 2007.
[5] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004.
[6] Ernst, T. and H. Lach, "Network Mobility Support Terminology",
draft-ietf-nemo-terminology-06 (work in progress),
November 2006.
[7] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[8] Ernst, T., "Network Mobility Support Goals and Requirements",
draft-ietf-nemo-requirements-06 (work in progress),
November 2006.
[9] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
IKEv2 and the revised IPsec Architecture",
draft-ietf-mip6-ikev2-ipsec-08 (work in progress),
December 2006.
Wakikawa, et al. Expires September 6, 2007 [Page 32]
Internet-Draft MCoA March 2007
12.2. Informative References
[10] Ernst, T., Montavont, N., Wakikawa, R., Ng, C., and K.
Kuladinithi, "Motivations and Scenarios for Using Multiple
Interfaces and Global Addresses",
draft-ietf-monami6-multihoming-motivation-scenario-01 (work in
progress), October 2006.
[11] Ng, C., Paik, Ernst, and C. Bagnulo, "Analysis of Multihoming
in Network Mobility Support",
draft-ietf-nemo-multihoming-issues-06 (work in progress),
June 2006.
[12] Soliman, H., "Flow Bindings in Mobile IPv6",
draft-soliman-monami6-flow-binding-02 (work in progress),
September 2006.
Appendix A. Example Configurations
In this section, we describe typical scenarios when a mobile node has
multiple network interfaces and acquires multiple Care-of Addresses
bound to a Home Address.
The Home Address of the mobile node (MN in figures) is a:b:c:d::EUI.
MN has 3 different interfaces and possibly acquires care-of addresses
1-3 (CoA1, CoA2, CoA3). The MN assigns BID1, BID2 and BID3 to each
care-of address.
Figure 3 depicts the scenario where all interfaces of the mobile node
are attached to foreign links. After binding registrations, the home
agent (HA) and the Correspondent Node (CN) have the binding entries
listed in their binding cache database. The mobile node can utilize
all the interfaces.
Wakikawa, et al. Expires September 6, 2007 [Page 33]
Internet-Draft MCoA March 2007
+----+
| CN |
+--+-+
|
+---+------+ +----+
+------+ Internet |----------+ HA |
| +----+---+-+ +--+-+
CoA2| | | | Home Link
+--+--+ | | ------+------
| MN +========+ |
+--+--+ CoA1 |
CoA3| |
+---------------+
Binding Cache Database:
home agent's binding (Proxy neighbor advertisement is active)
binding [a:b:c:d::EUI care-of address1 BID1]
binding [a:b:c:d::EUI care-of address2 BID2]
binding [a:b:c:d::EUI care-of address3 BID3]
correspondent node's binding
binding [a:b:c:d::EUI care-of address1 BID1]
binding [a:b:c:d::EUI care-of address2 BID2]
binding [a:b:c:d::EUI care-of address3 BID3]
Figure 3: Multiple Interfaces Attached to a Foreign Link
Figure 4 depicts the scenario where MN returns home with one of its
interfaces. After the successful de-registration of the binding to
HA, HA and CN have the binding entries listed in their binding cache
database of Figure 4. MN can communicate with the HA through only
the interface attached to the home link. On the other hand, the
mobile node can communicate with CN from the other interfaces
attached to foreign links (i.e. route optimization). Even when MN is
attached to the home link, it can still send Binding Updates for
other active care-of addresses (CoA2 and CoA3). If CN has bindings,
packets are routed to each Care-of Addresses directly. Any packet
arrived at HA are routed to the primary interface.
Wakikawa, et al. Expires September 6, 2007 [Page 34]
Internet-Draft MCoA March 2007
+----+
| CN |
+--+-+
|
+---+------+ +----+
+------+ Internet |----------+ HA |
| +--------+-+ +--+-+
CoA2| | | Home Link
+--+--+ | --+---+------
| MN +========+ | |
+--+--+ | | |
CoA3| +---|-----------+
+---------------+
Binding Cache Database:
home agent's binding (Proxy neighbor advertisement is inactive)
none
correspondent node's binding
binding [a:b:c:d::EUI care-of address2 BID2]
binding [a:b:c:d::EUI care-of address3 BID3]
Figure 4: One of Interface Attached to Home Link and Returning Home
Figure 5 depicts the scenario where MN disables the interface
attached to the home link and communicates with the interfaces
attached to foreign links. The HA and the CN have the binding
entries listed in their binding cache database. MN disable the
interface attached to the home link, because the HA still defends the
home address of the MN by proxy neighbor advertisements. All packets
routed to the home link are intercepted by the HA and tunneled to the
other interfaces attached to the foreign link according to the
binding entries.
Wakikawa, et al. Expires September 6, 2007 [Page 35]
Internet-Draft MCoA March 2007
+----+
| CN |
+--+-+
|
+---+------+ +----+
+------+ Internet |----------+ HA |
| +----+-----+ +--+-+
CoA2| | | Home Link
+--+--+ | --+---+------
| MN +========+ |
+--+--+ CoA1 |
| |
+---------------------------+
(Disable interface)
Binding Cache Database:
home agent's binding (Proxy neighbor advertisement is active)
binding [a:b:c:d::EUI care-of address1 BID1]
binding [a:b:c:d::EUI care-of address2 BID2]
correspondent node's binding
binding [a:b:c:d::EUI care-of address1 BID1]
binding [a:b:c:d::EUI care-of address2 BID2]
Figure 5: One of Interface Attached to Home Link and Not Returning
Home
Figure 6 depicts the scenario where multiple interfaces of MN are
attached to the home link. The HA and CN have the binding entries
listed in Figure 6 in their binding cache database. The MN can not
use the interface attached to a foreign link unless a CN has a
binding for the interface. All packets which arrive at the HA are
routed to one of the MN's interfaces attached to the home link.
Wakikawa, et al. Expires September 6, 2007 [Page 36]
Internet-Draft MCoA March 2007
+----+
| CN |
+--+-+
|
+---+------+ +----+
+------+ Internet |----------+ HA |
| +----------+ +--+-+
CoA2| | Home Link
+--+--+ --+----+---+------
| MN +===================+ |
+--+--+ |
| |
+---------------------------+
Binding Cache Database:
home agent's binding (Proxy neighbor advertisement is inactive)
none
correspondent node's binding
binding [a:b:c:d::EUI care-of address2 BID2]
Figure 6: Several Interfaces Attached to Home Link and Returning Home
Figure 7 depicts the scenario where interfaces of MN are attached to
the foreign links. One of foreign link is managed by the home agent.
The HA and CN have the binding entries listed in Figure 7 in their
binding cache database. The home agent advertises a prefix which is
other than home prefix. The mobile node will generate a care-of
address from the prefix and registers it to the home agent. Even if
the mobile node attaches to a foreign link, the link is managed by
its home agent. It will tunnel the packets to the home agent, but
the home agent is one-hop neighbor. The cost of tunnel is
negligible. If the mobile node wants to utilize not only an
interface attached to home but also interfaces attached to foreign
link, it can use this foreign link of the home agent to return a one
hop foreign link on behalf of a home link. This is different from
the general returning home, but this enable the capability of using
interfaces attached to both home and foreign link without any
modifications to Mobile IPv6 and NEMO basic support.
Wakikawa, et al. Expires September 6, 2007 [Page 37]
Internet-Draft MCoA March 2007
+----+
| CN |
+--+-+
|
+---+------+ +----+
+------+ Internet |----------+ HA |
| +----+-----+ ++-+-+
CoA2| | | | Home Link
+--+--+ | ----|-+------
| MN +========+ |
+--+--+ CoA1 ---+-+------
CoA3 | | Foreign Link
+---------------------------+
Binding Cache Database:
home agent's binding (Proxy neighbor advertisement is active)
binding [a:b:c:d::EUI care-of address1 BID1]
binding [a:b:c:d::EUI care-of address2 BID2]
binding [a:b:c:d::EUI care-of address3 BID3]
correspondent node's binding
binding [a:b:c:d::EUI care-of address1 BID1]
binding [a:b:c:d::EUI care-of address2 BID2]
binding [a:b:c:d::EUI care-of address3 BID3]
Figure 7: Emulating to Utilize Interfaces Attached to both Home and
Foreign Links
Wakikawa, et al. Expires September 6, 2007 [Page 38]
Internet-Draft MCoA March 2007
Appendix B. Changes From Previous Versions
Changes from draft-ietf-monami6-multiplecoa-01.txt
o Updating the text of BID definition. The older text was unclear
whether a BID is assigned to a binding or a interface. It is now
clearly defined that BID is assigned to each binding.
o Removing R flag according to complexity.
o Introducing O (Overwrite) flag. This flag is useful when a MN
sends all the active CoAs to HA or CN all at once. It also useful
when a MN reboots and sends a first BU to HA and CN. see
Section 5.11 in detail.
o Removing the Binding Error texts, since there is no way to know
BID when BE is sent by CN.
o Clearing up the Status code of Binding Unique Identifier sub-
option and Binding Acknowledgment. Renewing the texts in
Section 6.3.
o Adding new section "Sending Packets to HA" and "Receiving Packets
from MN".
o adding how to handle correspondent nodes which do not support MCoA
extension in Section 5.2.
o Return routability is now extended to carry and use BID to
generate Authenticator. Section 6.2 and Section 5.2 are added.
o Adding a new section: IPsec and IKEv2 interaction.
o Shortening Introduction. We also remove several useless texts in
this doc.
Wakikawa, et al. Expires September 6, 2007 [Page 39]
Internet-Draft MCoA March 2007
Authors' Addresses
Ryuji Wakikawa
Keio University
Department of Environmental Information, Keio University.
5322 Endo
Fujisawa, Kanagawa 252-8520
Japan
Phone: +81-466-49-1100
Fax: +81-466-49-1395
Email: ryuji@sfc.wide.ad.jp
URI: http://www.wakikawa.org/
Thierry Ernst
INRIA
INRIA Rocquencourt
Domaine de Voluceau B.P. 105
Le Chesnay, 78153
France
Phone: +33-1-39-63-59-30
Fax: +33-1-39-63-54-91
Email: thierry.ernst@inria.fr
URI: http://www.nautilus6.org/~thierry
Kenichi Nagami
INTEC NetCore Inc.
1-3-3, Shin-suna
Koto-ku, Tokyo 135-0075
Japan
Phone: +81-3-5565-5069
Fax: +81-3-5565-5094
Email: nagami@inetcore.com
Vijay Devarapalli
Azaire Networks
3121 Jay Street
Santa Clara, CA 95054
USA
Email: vijay.devarapalli@azairenet.com
Wakikawa, et al. Expires September 6, 2007 [Page 40]
Internet-Draft MCoA March 2007
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Wakikawa, et al. Expires September 6, 2007 [Page 41]
