One document matched: draft-wakikawa-mobileip-multiplecoa-01.txt
Differences from draft-wakikawa-mobileip-multiplecoa-00.txt
Mobile IP Working Group Ryuji Wakikawa
INTERNET DRAFT Keisuke Uehara
24 June 2003 Thierry Ernst
Keio University/WIDE project
Multiple Care-of Address Registration on Mobile IPv6
draft-wakikawa-mobileip-multiplecoa-01.txt
Status of This Memo
This document is a submission to the Mobile IP Working Group of the
Internet Engineering Task Force (IETF). Comments should be submitted
to the mobile-ip@sunroof.eng.sun.com mailing list.
Distribution of this memo is unlimited.
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. 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.
Abstract
This draft proposes extensions of Mobile IPv6 in order to register
multiple care-of addresses to a home agent and correspondent nodes.
This draft also targets Network Mobility (NEMO). According to the
current specification of Mobile IPv6, a mobile node can register only
one of care-of addresses as its primary care-of address even if the
mobile node has multiple active care-of address. However, it is
useful to get Internet access through multiple access media (i.e.
care-of addresses) simultaneously in terms of bandwidth, delay,
and etc. Our extensions are thus designed to register multiple
care-of addresses bound to a single home address to a home agent and
correspondent nodes. For doing so, we propose a new identification
number for each interface of a mobile node. The mobile node
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registers a care-of address with the identification number so that
the receiver can distinguish the binding.
Contents
Status of This Memo 1
Abstract 1
1. Introduction 3
2. Multiple Network Interface vs Multiple Care-of Address 5
3. Terminology 5
4. Protocol Overview 6
5. Mobile IPv6 Extension 7
5.1. Binding Cache Structure and Management . . . . . . . . . 8
5.2. Binding Update Structure and Management . . . . . . . . . 8
5.3. Messages Format Changes . . . . . . . . . . . . . . . . . 9
5.3.1. CoA InFormation sub-option . . . . . . . . . . . 9
5.3.2. Binding Update . . . . . . . . . . . . . . . . . 9
5.3.3. Binding Acknowledgment . . . . . . . . . . . . . 10
6. Return Routability Procedure 10
7. Mobile Node Operation 12
7.1. Management of care-of addresses . . . . . . . . . . . . . 12
7.2. Management of Multiple Care-of addresses on the interface 13
7.3. Sending Binding Update . . . . . . . . . . . . . . . . . 13
7.4. Receiving Binding Acknowledgment with CoAINFO sub-option 14
7.5. Receiving Binding Refresh Request with CoAINFO sub-option 15
7.6. Receiving Binding Error . . . . . . . . . . . . . . . . . 15
7.7. De-registration of one of care-of addresses . . . . . . . 15
7.8. Movement Detection . . . . . . . . . . . . . . . . . . . 16
8. Correspondent Node Operation 16
8.1. Selection of care-of address for outgoing packets . . . . 16
8.2. How to search the binding cache . . . . . . . . . . . . . 16
8.3. Receiving Binding Update . . . . . . . . . . . . . . . . 16
8.4. Sending Binding Acknowledgment . . . . . . . . . . . . . 17
8.5. Sending Binding Refresh Request . . . . . . . . . . . . . 17
8.6. Sending Binding Error . . . . . . . . . . . . . . . . . . 18
9. Network Mobility Applicability 18
10. Security Consideration 18
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11. Changes from the version 00 19
Acknowledgments 19
References 19
Authors' Addresses 20
1. Introduction
Permanent Internet connectivity is required by some applications
while a mobile node (MN) moves across several access networks (i.e.
ISPs, hotspots, etc). For example, it is desirable to maintain
the Internet connectivity while an automobile running on a freeway
receives voice or video streaming data from different access network.
Unfortunately, there is no network interface assuring global scale
connectivity. Therefore, the MN should use various type of network
interfaces to obtain wide areas network connectivity [8]. In
addition, users should select the most appropriate network interface
depending on the visiting network environment, since wireless
networks is mutable and less reliable than wired networks and
each network interface has different cost, performance, bandwidth,
access range, and reliability. A user should also select the most
appropriate interface per communication. For example, TCP [7]
communication should be transmitted over wireless interface, but UDP
communication should be sent over wired interface not to disturb TCP
connections.
Associating multiple care-of addresses to a home address would
enable durable Internet connectivity [9] [1] [10]. For example,
when a MN loses its Internet connectivity at one of the interface,
it can use the second interface as a backup interface and still
keeps connectivity to the network. In addition, the MN can send
each communication flow to a distinct network interface. This
provides efficient network bandwidth consumption. A user can
select the most suitable network interface per application.
Correspondent Nodes (CNs) can also re-select a binding of MN to
recover communication when one of MN's CoA becomes invalid. To put
binding selection policy to each binding, MN can use a binding for
specified communication type. If MN does not have enough bandwidth
for communications, it can utilize both of bindings to gain network
bandwidth. Furthermore, MN may bicast packets through every network
interfaces for some flow.
IPv6 [2] conceptually allows a node to have several addresses
on an interface. On the other hand, according to section 11.5.3
of [6], current Mobile IPv6 [6] does not allow a MN to register
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multiple care-of addresses bound to a single home address. If a MN
sends Binding Update (BU) for each care-of addresses , CNs always
overwrites the existing binding to the received binding update. It
is impossible for a MN to register multiple care-of addresses in CN's
binding cache.
Mobile IPv6 [6] has mechanisms to manage multiple ``home addresses''
based on home agent's managed prefixes such as mobile prefix
solicitation, mobile prefix advertisement. The advantage of using
single home address compared to multiple home addresses assigned to
each network interface is that applications do not need to be aware
of the difference in home addresses. Of course, a MN can assign
multiple home addresses per network interfaces, but applications
should be aware of the active home address for communication. At
the TCP layer, TCP holds the home address as a source address of the
communication for connection managements. Thus, applications must
reboot to reset the connection information when the the MN changes
the active network interface (i.e. change the home address).
In this document, we thus propose a new identification number called
IFID and a priority value (IFPRI) for each interface to accommodate
multiple care-of addresses. We also propose extension of binding
cache management to store IFID, new sub-options for binding update
to carry IFID. MN assigns an IFID and an IFPRI to either a single
or multiple network interfaces bound to a single home address in
Mobile IPv6. MN notifies the IFID and the IFPRI to both HA and CN
by BU. CN and HA record the IFID and the IFPRI into their binding
cache database. Therefore, CNs and HA distinguish multiple care-of
addresses by using the IFID. A home address identifies a mobile node
itself and the IFID identifies each network interfaces installed in
a mobile node. A user of a mobile node may be able to bind some
policies to the IFID. The policy is used to divide flow to multiple
network interfaces by flow type, port number, or destination address,
etc. How to distribute or configure policy is currently out of scope
in this draft.
The multiple care-of address extensions specified in this draft also
target Network Mobility (NEMO) support based on Mobile IPv6 [3].
Our extensions can indeed be applied to either a mobile host
(Mobile IPv6) or a mobile router (MR, see [5]). Network Mobility
Support must allow multihoming so as to provide robustness, better
performance, etc described in [4]. Multihoming include in particular
the ability to switch from one egress interface to another.
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2. Multiple Network Interface vs Multiple Care-of Address
There are two cases when a MN has several care-of addresses.
- MN uses several physical network interfaces to acquire a care-of
address.
- MN uses single physical network interface, but it acquires
several addresses from the attached network. Since IPv6 allows
to have several addresses on single network interface, it is
possible to get several global address with a network interface
at the attached network.
The difference between above two cases is a number of physical
network interfaces. This draft basically handles the several network
interfaces. To accommodate the second situation, this document
treats single interface as MN pseudoly having multiple network
interfaces. (i.e. if MN has multiple care-of addresses at the
single interface, Mobile IPv6 treats each care-of address is assigned
to each pseudo interface.) For example, MN obtained care-of address1
and care-of address2 at interface-A, MN treats this like: care-of
address1 is assigned to interface-A and care-of address2 is assigned
to pseudo-interface-B. If care-of address1 is deleted due to the
expiration of router lifetime, MN removes the pseudo interface-B. The
more protocol operation is described in the section 7.2.
3. Terminology
Most of terms used in this draft are defined in [6].
InterFace IDentification number (IFID)
The identification number which is used to distinguish
each interface on MN. IFID is assigned to each interface,
and generated randomly not to duplicate each other. If an
interface has multiple care-of addresses, then MN can assign
IFID to a pseudo interface. MN has to assign different IFID
for each destination node. This is for security policy. If MN
uses same IFID to all destination nodes, it will always reveal
all interface information to all nodes. MN sometime hides some
of interface from specific destination nodes.
InterFace PRIority (IFPRI)
The priority value can be used to select a care-of address
on CN. The care-of address which has the highest priority is
the primary care-of address. Lower value indicates higher
priority. Zero indicates primary interface. If an interface
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has multiple care-of addresses, then MN can assign IFPRI to
each care-of address.
Primary InterFace (P-IF)
The interface which is assigned a primary care-of address.
Once the primary interface goes invalid due to movements,
MN MUST reselect primary interface from set of interfaces
installed in MN.
Non-Primary InterFace(NP-IF)
The interface which is NOT assigned the primary care-of
address.
Primary care-of address (P-CoA)
The primary care-of address is defined as ``the care-of address
registered with the MN's home agent is called its ``primary''
care-of address'' in [6].
In this draft, the definition is extended as follows. The
care-of address which is primary associated with a home address
and is assigned to a P-IF. MN MUST have PCoA all the time.
Once PCoA goes invalid, MN MUST reselect PCoA from the multiple
care-of addresses that a MN may have at any given time.
Non-Primary care-of address (NP-CoA)
The care-of address which is NOT selected as primary (i.e.
``non-primary'' CoA).
Care-of Address Information sub-option (CoAINFO)
The CoA information sub-option is used to notify IFID and IFPRI
with BU.
Multiple Care-of Addresses Flag (M flag)
A flag which indicated a CoAINFO sub-option is included in the
BU's mobility option field.
4. Protocol Overview
We propose a new identification number (IFID) for each interface.
Once a MN gets several CoAs on distinct interfaces, it MUST select a
primary CoA from active CoAs as specified in Section 11.5.3 of [6].
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After the selection, the interface which has the primary CoA becomes
the primary interface on the MN.
When a MN acquires multiple care-of addresses for a home address, it
SHOULD notify all of them to CN. Even when a CoA goes invalid, CN
still have another registered CoA for the MN. Thus, CN can switch
to an active CoA as soon as it detects CoA's invalidation. CN can
detect CoA's invalidation by packets loss or ICMP error messages
such as ICMP_UNREACHABLE. If the MN does not have enough bandwidth
for outgoing packets, the MN can utilize multiple network interfaces
simultaneously, and divide flow to each network interface.
The MN registers only its primary CoA to its Home Agent (HA) as the
home registration. After the home registration, the MN MAY send BU
to CNs through Return Routability (RR) procedure. The MN starts
to send HoTI and CoTI for the primary CoA. If the MN has another
non-primary CoA, it also sends CoTI for the non-primary CoA which can
be assigned to any interface. This CoTI is sent with the non-primary
CoA set to the source address field of the IPv6 header. The MN MUST
add CoAINFO sub-option containing IFID and IFPRI of the interface
which is assigned to the target CoA in each CoTI message. These
values are securely notified to CNs by RR operations. After getting
HoT and CoT for either primary CoA or non-primary CoA, the MN sends
BU with IFID and IFPRI for the CoA which is authenticated by CoT. To
register both CoAs to CNs, the MN MUST sends BUs for each CoA.
When a CN receives a BU with a CoAINFO sub-option containing an IFID
and an IFPRI, it checks binding cache for the home address and the
IFID stored in the CoAINFO sub-option. If both are matched, the CN
updates the binding with the new CoA (stored in the BU). Otherwise,
it creates new binding for the home address and the IFID even if it
has already had a binding for the same home address, because the
recorded IFID is different from the requesting IFID.
Whenever the MN moves and changes the CoA for a given interface, it
MUST send BU with the IFID of the changed interface. MN can always
update the particular CoA with the IFID. When the MN returns home, it
MUST de-register all the bindings by BU which lifetime set to zero
regardless of availability of another care-of addresses. When MN
detects that the primary interface is attached to the home link, it
indicates MN's returning home.
5. Mobile IPv6 Extension
Mobile IPv6 should be able to manage multiple care-of addresses. The
changes are described in this section.
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5.1. Binding Cache Structure and Management
This document requires to have additional items for the binding cache
structure, which are
- IFID
The IFID of the registered care-of address. The IFID is notified
by BU sent by MN. The IFID is protected by return routability
procedure described in section 6.
- IFPRI
The IFPRI of the registered care-of address. The priority is
notified by BU. Whenever a BU is received, the priority value
MUST be overwritten to newest one. The IFPRI is also protected
by return routability procedure described in section 6.
If a node gets a BU with a CoAINFO defined at 5.3.1, it searches
Binding Cache entries with the set of the home address and the IFID.
If both does match with the registered binding, the node MUST update
the CoA and the IFID into the matched binding. Otherwise, the node
MUST register a new binding for the CoA and the IFID, even if there
are already the other binding for the MN's home address.
5.2. Binding Update Structure and Management
This document requires to have additional items for binding update
structure, which are
- IFID
The IFID of the care-of address MUST be recorded in the binding
update list.
- IFPRI
The priority of the care-of address MUST be recorded in the
binding update list.
If MN has multiple care-of addresses at a time, it SHOULD assign a
IFID and a IFPRI to each care-of address. The IFID and the IFPRI
should be recorded in the binding update list. MN SHOULD update
the value of the IFID periodically not to be discovered by a third
person. The value of IFPRI can be changed at any time.
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5.3. Messages Format Changes
5.3.1. CoA InFormation sub-option
The CoAINFO sub-option can be included in Binding Update, Binding
Acknowledgment, Binding Refresh Request, Binding Error if needed.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = TBD | Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IF ID | IFPRI | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
Type
Type value for CoAINFO will be assigned later.
Length
The value MUST be always 2.
IFID
The IFID of the care-of address which is notified by this
BU with CoAINFO.
IFPRI
The IFPRI of the care-of address which is notified by this
BU with CoAINFO.
Reserved
16 bit Reserved field. Reserved field must be set with all
0.
5.3.2. Binding Update
If MN wants to register several CoAs which would be bound to a
home address, MN MUST set 'M' flag and include the CoA information
sub-option. The sub-option is constructed according to the binding
update list.
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|H|L|K|R|M| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mobile Router Flag (R)
This flag is proposed by the NEMO working group [3].
Multiple Care-of Addresses Flag (M)
This flag is used for multiple care-of address registration.
Reserved
Reserved field is reduced to 11 bits.
5.3.3. Binding Acknowledgment
The message format of Binding Acknowledgment is not changed, but
operations listed below are added in this draft.
The receiver who gets binding update with 'M' flag MUST reply BA if
'A' flag is set or BU is for home registration. The receiver MUST
also reply BA with correspondent error number if it finds some error
during processing BU and its sub-option described in section 5.3.2.
If a BU has 'M' flag and a CoAINFO sub-option, a CN MUST reply
BA containing the CoAINFO sub-option. To include the CoAINFO
sub-option, the sender (i.e. MN) can process the BA for the target
CoA specified by the CoAINFO sub-option.
This document defines new number for 'M' flag handling.
1 Successful registration of NP-CoA
6. Return Routability Procedure
The CoTI and CoT messages transaction must be modified to secure the
CoAINFO sub-option. Therefore, this draft describes only CoTI and
CoT, because both HoTI and HoT are not modified at all. Processing
of HoTI and HoT can be found at [6].
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Mobile node Home agent Correspondent node
| |
| 1b. |
| Care-of Test Init(CoTI) |
| Src = care-of address |
| Dst = correspondent |
| Parameters: |
| - care-of init cookie |
| - care-of address ID |
| - care-of address Priority |
|---------------------------------------------------->|
| |
| 2b. |
| Care-of Test(CoT) |
| Src = correspondent, |
| Dst = care-of address |
| Parameters: |
| - care-of init cookie |
| - care-of keygen token |
| - care-of nonce index |
|<----------------------------------------------------|
| |
1b. Care-of Test Init
The MN sends a Care-of Test Init message to the correspondent
node to acquire the care-of keygen token. The contents of this
message can be summarized as follows:
Src = care-of address
Dst = correspondent
Parameters:
+ care-of init cookie
+ care-of address ID (IFID)
+ care-of address Priority (IFPRI)
The second message conveys the MN's care-of address to the
correspondent node. The MN also sends along a care-of init
cookie that the correspondent node must return later. The
Care-of Test Init message is sent directly to the correspondent
node.
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2b. Care-of Test
This message is sent in response to a Care-of Test Init message.
The contents of the message are:
Src = correspondent
Dst = care-of address
Parameters:
+ care-of init cookie
+ care-of keygen token
+ care-of nonce index
The correspondent node also sends a challenge to the MN's care-of
address. When the correspondent node receives the Care-of Test
Init message, it generates a care-of keygen token as follows:
care-of keygen token = First (64, MAC (Kcn, (care-of address
| IFID | IFPRI | nonce)))
The keygen token is formed from the first 64 bits of the MAC
result, and sent directly to the MN at its care-of address. The
care-of init cookie from the from Care-of Test Init message is
returned to ensure that the message comes from a node on the
route to the correspondent node.
The care-of nonce index is provided to identify the nonce used
for the care-of keygen token. The home and care-of nonce indices
are often the same in the Home and Care-of Test messages.
7. Mobile Node Operation
7.1. Management of care-of addresses
A MN assigns IFPRI to each interface according to user's policy or
administrative policy. If the MN has only single interface, it
assigns ``zero value'' to the interface as P-IF.
A MN also assigns IFID to each interface. The value should be
randomly generated and assigned to each interface. If the MN has
single interface, assignment of IFID to the interface is not needed
until it has multiple interfaces.
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A MN MUST handle P-CoA normally as described in base Mobile IPv6
[6]. For example, ``home registration to HA'' and ``returning home''
is proceeded without any changes to Mobile IPv6 (i.e. same as the
section 11.7.1 and the section 11.5.4 of [6]). P-CoA MUST be the
care-of address on P-IF all the time.
A MN MUST manage multiple NP-CoA per NP-IF. Whenever the MN detects
the change of a NP-CoA by the prefix comparison between the NP-CoA
and received router advertisements sent by routers, it MUST start
appropriate operations such as updating the binding, de-registering
the binding, etc.
7.2. Management of Multiple Care-of addresses on the interface
If MN obtains several care-of address on an interface, MN has to
select an address as the P-CoA from the set of addresses. If MN
wants to register several care-of address on the same interface,
MN has to assign the ID to each of care-of address temporarily and
register the address by BU with CoAINFO sub-option. Once the address
is deleted from the interface, MN MUST de-register the address by
sending BU with lifetime zero and correspond CoAINFO sub-option. The
ID assigned to a CoA is available until the CoA is active. Whenever,
the CoA changed, the MN MUST de-register the older CoA and the older
ID and MUST assign a new ID for the new CoA.
7.3. Sending Binding Update
When a MN sends a BU to its home agent (i.e. home registration), the
MN should choose the P-CoA for home registration. The MN SHOULD NOT
register multiple CoAs to the HA with CoAINFO sub-options. The MN
SHOULD operate the home registration as Mobile IPv6 described in [6].
When the MN sends a BU to CNs, it MUST decide whether it registers
multiple CoAs to the CN or not. However, this decision is out-of
scope in this document.
- General Mobile IPv6
If the MN decides not to register multiple CoAs to the CN, it
just starts RR and sends BU using the home-registered P-CoA
according to [6].
- RR procedure for P-CoA
On the other hand, if the MN need to register multiple CoAs
to the CN, the MN first attempts to process registration of
its P-CoA to the CN. The MN sends HoTI, and CoTI with CoAINFO
sub-option. In the CoAINFO sub-option, the MN puts a randomly
generated IFID and a IFPRI set to zero (to indicate primary).
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These values MUST be recorded into the binding update list. An
IFID and an IFPRI for each interface MAY be configured beforehand
by users.
- Registration of P-CoA to a CN
Once the MN receives HoT and CoT from the CN, it prepares
for the BU. The BU must be constructed with 'M' flag and
contain a CoAINFO sub-option. The detail of BU is described in
section 5.3.2. The value of CoAINFO sub-option is copied from
the binding update list. Finally, the MN sends the BU to the
CN. The MN MUST wait a BA from the CN to confirm successfully
registration as described in section 7.4
- Registration of NP-CoAs to the CN
After registration of the P-CoA, the MN start processes of NP-CoA
registration. It sends CoTI with a CoAINFO sub-option and MAY
send HoTI as well. Since the MN has already received HoT from
the CN, sending HoTI CAN be skipped. When the value of the
CoAINFO sub-option for CoT is set, these values MUST be recorded
to the binding update list. After receiving CoT, it makes BU
including CoAINFO sub-option and 'M' flag. The value of CoAINFO
sub-option is copied from the binding update list. The MN MUST
wait a BA from the CN as described in section 7.4. The MN repeat
this operations for all possible care-of addresses.
7.4. Receiving Binding Acknowledgment with CoAINFO sub-option
Verification of Binding Acknowledgment is same as Mobile IPv6
(section 11.7.3 of [6]). The operation except for the text below
is described in the [6]. The operation of sending BA is described
in 8.4.
If MN sends BU with a CoAINFO sub-option, BA MUST contain the CoAINFO
sub-option. If BA does not have the CoAINFO sub-option, the CN might
not recognize CoAINFO sub-option. The MN SHOULD stop registering
multiple care-of addresses by CoAINFO sub-option.
If BA has the CoAINFO sub-option and the success status value (i.e.
1), it indicates successful registration of the care-of address which
IFID is in the CoAINFO sub-option.
If the BA's status code is zero (indicating successfully registration
in Mobile IPv6 [6]) regardless of CoAINFO sub-option availability in
BA, the MN MAY stop attempting multiple binding registration to the
CN. The successful status code is ``1'' on this document, therefore
the CN may not registered multiple care-of addresses respectively.
(i.e. CN overwrites the existing binding to the received BU)
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If the status field does not indicate success registration (i.e.
more than 128), it SHOULD stop registering the care-of address which
IFID is in the CoAINFO sub-option.
7.5. Receiving Binding Refresh Request with CoAINFO sub-option
Verification of Binding Refresh Request is same as Mobile IPv6
(section 11.7.4 of [6]). Operation except for text below is
described in the [6]. The operation of Sending Binding Refresh
Request (BRR) is described in the section 8.5.
If CN receives a BRR with a CoAINFO sub-option, this BRR indicates
BRR for the interface of IFID stored in the CoAINFO sub-option. The
MN MAY send BU for the care-of address which is assigned to the
interface.
If BRR does not contain a CoAINFO sub-option and if the MN has
the binding update list for the requesting node, the MN sends BU
according to the binding update list. On the other had, if the MN
does not have any binding update list for the requesting node, the MN
sends BU according to the section 7.3.
7.6. Receiving Binding Error
When a MN receives BE with a CoAINFO sub-option, the BE is for the
interface which IFID is stored in the CoAINFO sub-option. Further
operations except for the text below are same as [6]. The operation
of sending BE is described in the section 8.6.
If the message Status field is 2 (unrecognized MH Type value)
regardless of CoAINFO sub-option availability, the MN should stop
sending CoAINFO sub-option to the CN. Instead, the MN should register
only P-CoA to the CN.
7.7. De-registration of one of care-of addresses
When a MN need to de-register one of care-of address, it sends a BU
with a CoAINFO sub-option to the CN. The BU MUST contain the lifetime
specified as zero and specify a Care-of address that matches the
home address for the binding. The CoAINFO sub-option MUST contain
IFID and IFPRI of the target interface. Otherwise, the CN can not
determine which binding should be deleted for this de-registration if
there are multiple bindings for the home address.
If a MN decided to delete all the binding from the CN, it sends
normal de-registration BU to the CN (i.e. exclusion of the CoAINFO
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sub-option from the above operation). see the section 8.3 for
details.
7.8. Movement Detection
If the new visiting network is not the home link, the MN just updates
the CoA (either P-CoA or NP-CoA). If one of the interface changes the
attached network and gets a different CoA regardless of primary or
not, MN must register the new CoA to CNs with a CoAINFO sub-option.
Whenever the P-IF is attached to the home link, the MN sends BU for
de-registration to the HA and CNs. If the NP-IF is attached to the
home link, MN de-register NP-CoAs attached to the information of
NP-IF to CNs, but it SHOULD NOT de-register the binding for the P-CoA
to the HA and CNs.
8. Correspondent Node Operation
8.1. Selection of care-of address for outgoing packets
If the CN registers multiple care-of addressed for a home address
in its binding cache, it can use any of the binding for outgoing
communication to the registering MN.
The selection of the best CoA is out of scope in the present
document. However, the CN MAY decide to choose the best binding by
the comparison of each registered priority value.
8.2. How to search the binding cache
Whenever the CN searches the binding cache for the home address, it
SHOULD uses both the home address and an IFID as a key of search if
it knows IFID. The CN basically knows an IFID when it receives an
CoAINFO sub-option. At the time, the CN MUST look up the binding
cache with the home address and the IFID retrieved from the CoAINFO
sub-option.
If the CN does not know the IFID, the CN search the binding with only
the home address as well as base Mobile IPv6. The CN can ignore the
knowing IFID, if it does not desire to use.
8.3. Receiving Binding Update
If the received a BU does not contain a CoAINFO sub-option or does
not have 'M' flag set, the processing of the BU is same as [6]. But
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if the CN has already registered multiple care-of addresses for the
home address, the CN MUST overwrite the binding for the home address
with the received BU. After receiving the BU which does not contain
a CoAINFO sub-option, the CN MUST have only a binding for the home
address.
The CN MUST validate the BU and the CoAINFO sub-option according
to the section 9.5.1 of [6]. If the received a BU contain a
CoAINFO sub-option or has 'M' flag set, the receiving node MUST
operate additional validation for the BU and the CoAINFO sub-option
additionally.
If the BU has 'M' flag at the flag field, it MUST contain a CoAINFO
sub-option. If it does not contains a CoAINFO sub-option, the CN
MUST silently drop the BU. If the CoAINFO sub-option is present, the
CN MUST register the IFID and the IFPRI to the MN's binding.
If the CN has already registered the binding for the home address and
IFID, then it MUST update the care-of address of the binding and the
IFPRI.
8.4. Sending Binding Acknowledgment
After processing the BU described in 8.3, the CN MUST reply BA either
when the 'A' bit is set to the BU or when the CN find an error during
processing BU described in [6].
If the BU does not contain a CoAINFO sub-option, the CN MUST reply BA
according to the section 9.5.4 of [6]. Otherwise, the CN MUST follow
the procedure below.
If the CN successfully registered the care-of address which
identified in CoAINFO sub-option, it returns BA with status set to
'1' (Successfully registration of NP-CoA) and the CoAINFO sub-option
copied from the BU.
If the CN encountered an error during processing BU, it must returns
BA with appropriate error number described in [6]. The CN MAY attach
the CoAINFO sub-option to notify the dropped interface to the MN.
8.5. Sending Binding Refresh Request
When a CN notices that the registered binding will expire soon, it
SHOULD send BRR. If the registered binding has IFPRI and IFID, the CN
SHOULD contain CoAINFO sub-option in BRR. Then, the CN can receive BU
with CoAINFO sub-option and update only the target binding. If the
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registered binding does not have IFPRI and IFID, then the CN sends
normal BRR.
8.6. Sending Binding Error
When a CN receives BU with an CoAINFO sub-option, it verifies the BU
according to the [6]. If the CN does not understand either the 'M'
flag or CoAINFO sub-option, it MUST return BE to the sender MN with
the status specified to '1'(Unrecognized MH Type value).
If the CN receives data packets with the home address destination
option, it MUST verify the IPv6 source address field. If the source
address is not registered in the CN's binding cache, the CN MUST
return BE to the sender MN with the status set to zero (Unknown
binding for Home Address destination option). Then, the MN MAY send
BU (with a CoAINFO sub-option) to register the new binding.
9. Network Mobility Applicability
This draft can be applied to the basic network mobility support
protocol [3] proposed in the NEMO working group. Multihoming is
required as R12 (The solution MUST function for multihomed MR and
multihomed mobile networks...) in [4]. Since binding managements
are same as Mobile IPv6, both a mobile router and a home agent
can support this draft to deal with multiple care-of addresses
registration in terms of a multihomed mobile router.
10. Security Consideration
The information of a CoAINFO can be protected by RR procedure. MN
adds the CoAINFO in CoTI. CN calculates a CoA keygen token based on
the MN's care-of address, the information of the CoAINFO (IFID and
IFPRI), and the CN's nonce. CN sends the CoA keygen token by CoT.
MN uses the CoA keygen token to calculate the authentication data
and puts the data to the authentication data sub-option. CN always
verify the information of the CoAINFO by comparison of authentication
data sub-option.
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11. Changes from the version 00
- Corrected composition and grammatical errors.
- Update the packet format of Binding Update due to R-bit proposed
by NEMO basic support.
- Clarify to support a NEMO Mobile Router, too.
Acknowledgments
The authors would like to thank Julien Charbon, Susumu Koshiba,
Hiroki Matutani, Koshiro Mitsuya, Masafumi Watari (in alphabetical
order), nacm group at KEIO University, and WIDE project for their
contributions.
References
[1] M. Baker, X. Zhao, S. Cheshire, and J. Stone. Supporting
mobility in mosquitonet. In Proceedings of the 1996 USENIX
Conference, Jan. 1996.
[2] S. Deering and R. Hinden. Internet Protocol, Version 6 (ipv6)
Specification. Request for Comments (Draft Standard) 2460,
Internet Engineering Task Force, December 1998.
[3] V. Devarapalli, R. Wakikawa, A. Petrescu, and P. Thubert. Nemo
Basic Support Protocol (work in progress). Internet Draft
(draft-ietf-nemo-basic-support-00), Internet Engineering Task
Force, June 2003.
[4] T. Ernst. Nemo Mobility Support Goals and Requirements (work in
progress). Internet Draft (draft-ietf-nemo-requirements-01),
Internet Engineering Task Force, May 2003.
[5] T. Ernst and H. Lach. Nemo Mobility Support Terminology (work
in progress). Internet Draft (draft-ietf-nemo-terminology-00),
Internet Engineering Task Force, May 2003.
[6] D. Johnson, C. Perkins, and J. Arkko. Mobility
support in IPv6 (work in progress). Internet Draft,
(draft-ietf-mobileip-ipv6-23.txt), Internet Engineering Task
Force, May 2003.
[7] J. Postel. Transmission Control Protocol. Request for Comments
(Standard) 793, Internet Engineering Task Force, September 1981.
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[8] M. Stemm and R. H. Katz. Vertical handoffs in wireless overlay
networks. Mobile Networks and Applications, 3(4):335--350,
1998.
[9] R. Wakikawa, K. Uehara, and J. Murai. Multiple Network
Interfaces Support by Policy-Based Routing on Mobile IPv6.
In The 2002 International Conference on Wireless Networks,
ICWN2002, Jul. 2002.
[10] X. Zhao, C. Castelluccia, and M. Baker. Flexible network
support for mobility. In The Second Annual International
Conference on Mobile Computing and Networking, Nov. 1998.
Authors' Addresses
Ryuji Wakikawa
Keio University and WIDE
5322 Endo Fujisawa Kanagawa
252 JAPAN
Phone: +81-466-49-1394 Thierry Ernst
EMail: ryuji@sfc.wide.ad.jp Keio University and WIDE
Fax: +81-466-49-1395 5322 Endo Fujisawa Kanagawa
252 JAPAN
Keisuke Uehara Phone: +81-466-49-1394
Keio University and WIDE EMail: ernst@sfc.wide.ad.jp
5322 Endo Fujisawa Kanagawa Fax: +81-466-49-1395
252 JAPAN
Phone: +81-466-49-1394
EMail: kei@wide.ad.jp
Fax: +81-466-49-1395
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