IETF Mobile IPv6 Working Group H. Jang
Internet-Draft J. Cheon
Expires: March 31, 2004 S. Singh
SAMSUNG AIT
Oct 2003
Simultaneous Registration of Multiple Care-of Addresses
draft-jang-mipv6-smreg-00.txt
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This Internet-Draft will expire on March 31, 2004.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This draft proposes a scheme that allows a mobile node to register a
primary care-of address(CoA) as well as one or more non-primary CoAs
by sending a single binding update message to the home agent and/or
correspondent node. This is achieved by using two new mobility
options defined in this draft. Mobile nodes that perform duplicate
address detection procedure, such as Advance DAD and Optimistic DAD
can benefit from this scheme. Proposed scheme does not require to
exchange CoTI and CoT messages, usually required for the registration
of each of the non-primary CoA(s). It also does not require to
maintain binding management key for each of the non-primary CoA(s).
Thus the proposed scheme reduces the signaling and processing
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overhead in Mobile IPv6 networks.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 5
4. Mobile Node Considerations . . . . . . . . . . . . . . . . . . 6
5. Home Agent Considerations . . . . . . . . . . . . . . . . . . 7
6. Correspondent Node Considerations . . . . . . . . . . . . . . 8
7. Message Formats . . . . . . . . . . . . . . . . . . . . . . . 9
7.1 Non-primary CoA Binding Request option . . . . . . . . . . . . 9
7.2 Non-primary CoA Binding Reply option . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
Normative References . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . 15
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1. Introduction
A mobile node may have multiple interfaces to support different
access technologies and current IPv6 specification allows
configuration of multiple IPv6 addresses on any interface.
After MN moves to foreign link, it configures new CoA using either
stateless[3] or stateful mechanisms[4]. It then registers this
address, termed as primary CoA, with the HA and/or CN and uses it to
communicate with the CNs. According to the current Mobile IPv6
specification[2], only single CoA is used to communicate with CN in
foreign network. However, it is helpful for MN to utilize multiple
CoAs for more reliable connectivity, bandwidth management, delay
reduction, etc. In the following environments MN MAY have one or more
non-primary CoAs for any or all of the prefixes available on its
current link:
o MN has multiple interfaces and receives a Router Advertisement with
different Prefix options from each interface in foreign network.
o MN receives Router Advertisements with different prefix options on
one interface.
o Both of above situations.
Multiple CoA Registration[5] and HA Filtering[6] are recently
proposed protocols designed to utilize multiple CoAs. But some steps
need to be taken to optimize the registration procedure of multiple
CoAs. Before using the newly generated address, MN SHOULD perform
Duplicate Address Detection procedure[3] in order to verify its
uniqueness. The completion time for different CoAs may vary. So MN
sends separate BU messages to HA for each of the CoAs. Most of this
BU message fields are same except CoA related information. This
results in signaling overhead in bandwidth constrained wireless
medium. Moreover, since the return routability procedure between the
MN and CN MUST be done for each of the CoAs, the situation may be
more aggravated. At this point, we propose the method to register
multiple CoAs, especially one or more non-primary CoAs with minimal
overhead. Note that the registration for the primary CoA remains
unchanged and can be done according to Mobile IPv6[2].
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119[1].
Most of terms used in this draft are defined in [2] and the following
terminology and abbreviations are used in this document.
Primary Binding
- The association of the home address of a mobile node with a
primary CoA for that mobile node, along with the remaining
lifetime of that association.
Non-Primary Binding
- The association of the home address of a mobile node with a
non-primary CoA for that mobile node, along with the remaining
lifetime of that association.
Non-primary CoA Binding Request Option
- The mobility option to carry the non-primary CoA and its
related information necessary for the non-primary binding. This
option is valid only in Binding Update messages.
Non-primary CoA Binding Reply Option
- The mobility option to carry the non-primary CoA and its
related information necessary for the non-primary binding. This
option is valid only in Binding Acknowledgement messages.
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3. Protocol Overview
The proposed scheme operates on optimized DAD solution, hence enables
the simultaneous registration for all available multiple CoAs by
using single BU message. Optimized DAD solutions such as Advance
DAD[7] and Optimistic DAD[8] are recently discussed in DNA BoF to
minimize DAD latency and support the prompt address configuration
after MN's handover. We think that with high probability it will be
deployed to solve the crucial problem in Mobile IPv6, which is to
minimize the handover latency. Based on optimized DAD solutions, the
proposed scheme enables MN to register one or more non-primary CoAs
by using new mobility options which are included in BU and BA used to
register a primary CoA. After handover, MN can configure all
available new CoAs through optimized DAD solution without delay and
register its primary CoA to the HA and/or CNs. At that time, MN can
also register additionally its one or more non-primary CoAs by using
Non-primary CoA Binding Request options which will be introduced in
Section 7.1. After the HA or CN receives the BU including Non-primary
CoA Binding Request options, it MUST send BA including Non-primary
CoA Binding Reply options to let MN know the binding status for each
Non-primary CoA. The bit 'P' in Binding Cache entry is newly defined
in this draft to mark if the entry is for the primary binding or
non-primary binding.
This scheme enables the registration of non-primary CoAs and avoids
sending the duplicate information in each separate BU message without
exchange of CoTI and CoT for each non-primary CoA, hence reducing the
signaling and processing overheads in MIPv6.
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4. Mobile Node Considerations
After Layer 3 handover, MN generates its New CoAs using stateless or
stateful mechanisms. When CoAs are generated using stateless manner
and an optimized DAD solution, all of them are available at the same
time right after MN's handover, thereby it is possible for a MN to
register all available CoAs at the same time. How to choose the
non-primary CoAs to register among multiple available non-primary
CoAs is out of scope of this draft. It may be done with help of
application programs.
If a MN configures only one new CoA or wants to register only one out
of several available new CoAs, then it MUST register this as a
primary CoA with HA according to [2]. Otherwise, it SHOULD send BU
with the non-primary CoA Binding Request options for all of the
non-primary CoAs that MN wants to use for the communication with the
CN. Main fields of the Non-primary CoA Binding Request option,
defined in section 7.1, are set as below:
o Lifetime is set to the requested lifetime for the Non-primary CoA.
o Non-primary CoA is set to the address which a MN wants to register
to HA or CN as a non-primary CoA. This address is bound to a home
address contained in Home Address option.
After sending BU message with Non-primary CoA binding request option,
MN MUST create new entry in its Binding Update List for each
non-primary CoA. The key for searching of Binding Update List SHOULD
be the destination IP address of BU and CoA. Note that all CoAs
whether its primary CoA or non-primary CoA is bound to the same home
address.
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5. Home Agent Considerations
Whenever HA receives a BU, it MUST validate and authenticate it
according to the steps described in Section 10.3.1 of [2]. If HA
decides to accept the BU, then it MUST process the BU as follows.
o HA MUST search the Binding Cache entry by using HoA in Home Address
option and primary CoA in Source Address as a key, and creates or
updates the corresponding Binding Cache entry according to [2]. In
addition, It SHOULD set the 'P' flag to indicate the primary binding.
The bit 'P' in the Binding Cache entry is newly defined to
differentiate the non-primary binding and primary binding.
o If the BU contains one or more Non-primary CoA Binding Request
options, additional operation SHOULD be done for each non-primary CoA
Binding Request option. HA MUST search the Binding Cache by using a
pair of HoA in Home Address option and non-primary CoA in Non-primary
CoA field in this option as a key.
- If such an entry already exists in Binding Cache, HA MUST update
its existing Binding Cache entry and SHOULD clear the 'P' flag to
indicate non-primary binding.
- Otherwise, HA MUST create Binding Cache entry for the non-primary
CoA and SHOULD clear 'P' flag to indicate non-primary binding.
HA SHOULD record the lifetime of non-primary CoA retrieved from the
Non-primary CoA Binding Request option in Binding Cache entry.
When the HA replies with BA to MN, it MUST include the Non-primary
CoA Reply Binding option for each Non-primary Request Binding option
to let MN know the binding status of each non-primary CoA. If HA
receives packets destined to MN, it MAY forward the packets to the
specific CoA based on its own predefined filtering policy[6].
How to choose the forwarding destination IP address among the
multiple registered CoAs is out of scope of this draft. If there is
no filtering policy, it SHOULD forward to the primary CoA by default.
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6. Correspondent Node Considerations
When the MN registers one or more CoAs to CN, the processing
procedures of the received BU in CN are the same as those in HA.
The procedure of return routability remains unchanged and follows
[2].
Originally, the binding management keys are maintained so as to
guarantee the integrity and authenticity of the BU, and according to
[2], a MN MUST perform the return routability procedure before
sending every BU to CN. However, in this scheme only single BU is
used to register multiple CoAs and there is no need to perform
additional return routability or to maintain the binding management
keys for multiple CoAs. Thus signaling overhead is reduced
significantly by omitting the exchange of CoTIs and CoTs for
non-primary CoAs.
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7. Message Formats
This section introduces the new mobility options, the Non-primary CoA
Binding Request option and the Non-primary CoA Binding Reply option,
to support the registrations for the non-primary CoAs.
7.1 Non-primary CoA Binding Request option
This is a new mobility option that MUST be included in BU messages to
carry non-primary CoA, when a MN wants to register them at the same
time as registering the primary CoA to a HA or CN.
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 (8) | Length (8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lifetime (16) | Seq # (8) | Reserved (8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Non-primary CoA (128) +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBA
Length
8-bit unsigned integer. length fields in units of
8 octets.
Lifetime
16-bit unsigned integer. The number of time units
remaining before the binding for the Non-primary CoA
MUST be considered expired. A value of zero indicates
that the Binding Cache entry for the non-primary CoA
MUST be deleted. One time unit is 4 seconds.
Sequence #
A 16-bit unsigned integer used to match a Non-primary
CoA Binding Request option and a corresponding Non-
primary CoA Binding Reply option.
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Reserved
These fields are unused. They MUST be initialized to
zero by the sender and MUST be ignored by the receiver.
7.2 Non-primary CoA Binding Reply option
This is a new mobility option that MUST be included in BA messages to
acknowledge binding status for non-primary CoA. This option is sent
by a HA or CN in response to the receipt of the BU which includes
Non-primary CoA Binding Request option.
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 (8) | Length (8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status (8) | Seq (8) | Lifetime (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBA
Length
8-bit unsigned integer. Length fields in units of 8
octets.
Lifetime
16-bit unsigned integer. The number of time units
remaining before the binding for the Non-primary CoA
MUST be considered expired. A value of zero indicates
that the Binding Cache entry for the non-primary CoA
MUST be deleted. One time unit is 4 seconds.
Reserved
These fields are unused. They MUST be initialized to
zero by the sender and MUST be ignored by the receiver.
Status
8-bit unsigned integer indicating the disposition of
Non-primary Binding Request option in BU. Values of
the Status field less than 128 indicate that the BU
was accepted by the receiving node. Values greater than
or equal to 128 indicate that the Non-primary Binding
Request option was rejected by the receiving node.
The status values are same those defined in Section
6.1.8 of [2].
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Besides, one more status is newly defined in this draft.
140 The registration for Non-primary CoA is not
supported.
Sequence #
This is copied from Sequence # field of corresponding
Non-primary CoA Binding Request option in the BU and used
by the MN to match the Non-primary CoA Binding Request
option and the corresponding Non-primary CoA Binding
Reply option in the BA.
Lifetime
The granted lifetime, in time units of 4 seconds, for
which the receiving node, HA or CN, SHOULD retain the
entry for this MN in its Binding Cache.
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8. Security Considerations
This draft proposes two new mobility options used for the
registration of multiple CoAs. These mobility options are included
within binding update message. Hence, this draft assumes that all the
security considerations applied to a general Mobile IPv6 node are
applied to this draft as well.
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Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in
IPv6", draft-ietf-mobileip-ipv6-24 (work in progress), July
2003.
[3] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[4] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M.
Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 3315, July 2003.
[5] Wakikawa, R., "Multiple Care-of Addresses Registration",
draft-wakikawa-mobileip-multiplecoa-02 (work in progress),
September 2003.
[6] Montavont, N. and T. Noel, "Home Agent Filtering for Mobile
IPv6", draft-montavont-mobileip-ha-filtering-v6-00 (work in
progress), July 2003.
[7] Han, Y., "Advance Duplicate Address Detection",
draft-han-mobileip-adad-01 (work in progress), July 2003.
[8] Moore, N., "Optimistic Duplicate Address Detection",
draft-moore-ipv6-optimistic-dad-03 (work in progress), September
2003.
Authors' Addresses
Hee-Jin Jang
SAMSUNG Advanced Institute of Technology
i-Networking Laboratory
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9615
EMail: heejin.jang@samsung.com
URI: http://home.postech.ac.kr/~arche
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Jung-Hoon Cheon
SAMSUNG Advanced Institute of Technology
i-Networking Laboratory
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9569
EMail: jh.ch@samsung.com
Shubhranshu Singh
SAMSUNG Advanced Institute of Technology
i-Networking Laboratory
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9552
EMail: shubhranshu@samsung.com
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Acknowledgement
Thank Y.Han and J.Choi who discussed together and gave the helpful
advice on this draft.
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