Internet DRAFT - draft-tsao-mip-multihoming-lowpower
draft-tsao-mip-multihoming-lowpower
Mobile IP Multihoming for Low Power Mobiles October 2005
MONAMI6 Working Group
Internet Draft Shiao-Li Tsao
National Chiao Tung University
Expires: April 2006 October 2005
Benefits of multiple care-of addresses and home addresses for low
power multimode mobiles
<draft-tsao-mip-multihoming-lowpower-00.txt>
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Copyright (C) The Internet Society (2005).
Abstract
It is expected that future mobile devices will equip multiple
wireless interfaces in order to access the Internet ubiquitously. For
such a multimode mobile node (MMN) that might have multiple home
addresses to associate with its interfaces, the MMN has to keep its
interfaces awake to listen the packets to these home addresses (HoAs).
Therefore, the MMN consumes a considerable energy to maintain the
reachablilities of these HoAs/interfaces. The draft presents the
benefits to use multiple care-of addresses and/or home addresses to
save the idle-mode power consumption of an MMN, and also discusses
the impacts and the requirements of the existing IETF protocols to
support the proposed low power operations.
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Mobile IP Multihoming for Low Power Mobiles October 2005
Table of Contents
1. Introduction ....................................................2
2. Terminology......................................................3
3. Scenarios........................................................3
3.1 An MMN with multiple HoAs and multiple CoAs.................3
3.2 An MMN with one HoA and multiple CoAs.......................5
4. Impact Analysis..................................................6
4.1 An MMN with multiple HoAs and multiple CoAs.................6
4.2 An MMN with one HoA and multiple CoAs.......................6
5. Summary and Future Work..........................................6
Security Considerations.............................................6
References..........................................................7
Author's Addresses..................................................7
1. Introduction
To support the access of Internet services from everywhere and at any
time, future mobile devices are expected to be multimode [2][4]. A
mobile node (MN) that equips multiple and heterogeneous wireless
interfaces might activate one or some of its interfaces
simultaneously to communicate with peer nodes. The benefits of
multihomed mobiles that are summarized in [2] include permanent and
ubiquitous access, redundancy, load sharing, load balancing, bi-
casting, preferences, and increased bandwidth. However, to activate
multiple interfaces simultaneously spends considerable energy of a
battery operated device, and the power consumption posts a serious
problem for a multimode mobile node (MMN). One possible solution is
to set interfaces to sleep if there is no packet to send through the
links, but the idle interfaces still consume a significant portion of
the total power consumption of a mobile. For example, the power
consumption of a single-mode cellular phone during idle is about 10mW,
but the power consumption of a cellular/WLAN dual-mode phone that
even both cellular and WLAN interfaces are set to sleep requires 50mW
to 100mW. The problem becomes more serious for a mobile with multiple
wireless interfaces, e.g. a 3G/WiMAX/WLAN/Bluetooth handset.
Another alternative to reduce the power consumption of an MMN is to
turn off some of its interfaces. However, the MMN might have home
addresses (HoAs) to associate with these turned-off interfaces, the
packets to these HoAs are lost. For example, a 3G/WLAN dual-mode
handset might have two HoAs, one for 3G interface and the other for
WLAN interface. To disable WLAN interface of the 3G/WLAN dual-mode
handset to save power, the packets to the HoA of the WLAN can not
be received.
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Here, we consider to utilize multiple care-of addresses (CoAs) and/or
HoAs for an MMN that could be always reachable by HoAs and can also
achieve energy-efficient operations during idle. We first present two
scenarios that an MMN could improve the energy-efficiencies of the
idle-mode operations by applying multiple CoAs and/or HoAs. Then,
we analyze the impacts and requirements of the existing IETF
protocols to support the proposed designs.
2. Terminology
This draft is based on the terminology defined in [1]. For these
terms which are used in this draft but not defined in the existing
IETF documents are listed below.
Multimode Mobile Node (MMN)
A mobile node equips with more than one wireless interface. Each
interface has zero, one or multiple home addresses (HoAs) and/or zero,
one or multiple care-of addresses (CoAs).
3. Scenarios
Two situations are considered in this draft. First, an MMN activates
multiple interfaces, and each interface associates with an HoA and a
CoA. The MMN decides to turn off some of its wireless interfaces in
order to save the power, but does not want to lose packets to these
HoAs/interfaces that are turned off. The second situation is that an
MMN activates multiple interfaces, each interface associates with a
CoA, but all interfaces share the same HoA. The MMN decides to turn
off some of its wireless interfaces in order to save the power, while
the MMN receives the packets to the HoA via a particular wireless
interface, it turns on its preferred interface to communicate with
peer nodes.
3.1 An MMN with multiple HoAs and multiple CoAs
In this situation, an MMN has an HoA for each wireless interface (IF).
The MMN acquires a CoA in the visiting network and registers the CoA
to the home agent (HA) of the HoA for a particular interface. The MMN
might associate multiple HoAs which are multi-prefixed for one
interface, but here, we assume the each interface has one HoA in its
home network (HNW), and one CoA in the visiting network (VNW). Figure
1 shows an example. Step 1 to Step 6 of Figure 1 demonstrate the
message exchanging between the MMN and HAs. In order to save the
power, the MMN decides to turn off interface two (IF#2) and interface
three (IF#3), but it still wants to receive packets to home addresses
of IF#2 and IF#3, i.e. HoA#2 and HoA#3. Then, the MMN uses the HoA#1
as the CoA to register HA#2 and HA#3, i.e. Step 7 and Step 9. Once
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Mobile IP Multihoming for Low Power Mobiles October 2005
the CoA registration is complete, the MMN can turn off the IF#2 and
IF#3 to conserve the energy. In Step 11, the packets sent to HoA#3 of
IF#3 are received by the HA#3, the packets are forwarded to the CoA
of IF#3, i.e. the HoA#1. The HA#1 receives the packets, and forwards
the packets to CoA#1 so that the MMN can receive the packets via the
IF#1. Since the MMN can detect the packets which are sent to MMN's
HoA#3, the packets can be seen as paging packets to wake up the MMN's
IF#3. The MMN can either use the CoA#1/IF#1 to update the binding on
the correspondent node (CN) if the MMN prefers to use the IF#1 to
communicate with the CN. Otherwise, the MMN can turn on the IF#3,
acquires the CoA#3, and updates the binding on CN and HA#3. To use
multiple care-of addresses and home addresses for MMNs can reduce the
power consumption of MMNs in the idle mode and all home addresses of
the MMNs are always reachable even some interfaces are turned off.
MMN Visiting Networks Home Networks
IF#1 IF#2 IF#3 VNW#1 VNW#2 VNW#3 HNW#1 HNW#2 HNW#3
| | | | | | | | |
|1. acquire CoA#1 | | | | | |
|<---------------->| | | | | |
|2. register CoA#1 to HA#1 | | | |
|<-------------------------------------->| | |
| | | | | | | | |
| |3. acquire CoA#2 | | | | |
| |<------------------>| | | | |
| |4. register CoA#2 to HA#2 | | | |
| |<---------------------------------------->| |
| | | | | | | | |
| | |5. acquire CoA#3 | | | |
| | |<-------------------->| | | |
| | |6. register CoA#3 to HA#3 | | |
| | |<------------------------------------------>|
| | | | | | | | |
| |7. use HoA#1 as CoA to register HA#2 | |
| |<---------------------------------------->| |
| |8. turn off IF#2 | | | | |
| X | | | | | | |
| | | | | | | |
| |9. use HoA#1 as CoA to register HA#3 |
| |<------------------------------------------>|
| |10. turn off IF#3 | | | |
| X | | | | | |
| | | | | | |
| 11. incoming packets to HA#3, forwarded to HoA#1 |
| | | | |<----------|<--
| 12. packets forwarded to CoA#1, then to the MMN via IF#1
|<-----------------|<--------------------| | |
| 13. wake up IF#3, acquire CoA#3, BU CN, and HA#3 |
| X | | | | | |
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Mobile IP Multihoming for Low Power Mobiles October 2005
| |<-------------------------------------------...
| | | | | | | |
Figure 1. An MMN with multiple HoAs and multiple CoAs
3.2 An MMN with one HoA and multiple CoAs
The second situation is that an MMN has multiple interfaces, each
interface associates with a CoA, but all interfaces share the same
HoA. Figure 2 shows an example. Step 1 to Step 6 demonstrate to bind
multiple CoAs to a given HoA. The binding update should have the
information to tell the HA the priorities or the preferences of the
interfaces from which an MMN prefers to receive the packets. Then,
the MMN can turn off some of its wireless interfaces, i.e. Step 7 of
Figure 2, to save the power. While incoming packets are received by
the HA, it forwards the packets to MMN's CoAs based on the
preferences of priorities. Once the MMN receives the packets, the MMN
further decides and turns on a proper interface to communicate with
peer nodes. To use multiple care-of addresses for one home addresses
for MMNs can also reduce the power consumption of an MMN in the idle
mode.
MMN Visiting Networks Home Networks
IF#1 IF#2 IF#3 VNW#1 VNW#2 VNW#3 HNW#1
| | | | | | |
|1. acquire CoA#1 | | | |
|<---------------->| | | |
|2. register CoA#1 to HA#1 (preferred paging CoA)
|<-------------------------------------->|
| | | | | | |
| |3. acquire CoA#2 | | |
| |<------------------>| | |
| |4. register CoA#2 to HA#1 | |
| |<---------------------------------->|
| | | | | | |
| | |5. acquire CoA#3 | |
| | |<-------------------->| |
| | |6. register CoA#3 to HA#1 |
| | |<------------------------------>|
| |7. turn off IF#2 and IF#3 | |
| X X | | | |
| | | | |
| | | | |
| 8. incoming packets to HA#1, forwarded to CoA#1 first
| |<--------------------|<--
| 9. packets sent to the MMN via IF#1 |
|<-----------------| | | |
| 10. MMN decides to use IF#3 to communicate with the CN
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| 11. MMN wakes up IF#3, acquire CoA#3, BU the CN
| X | | | |
| |<--------------------------------...
| | | | | |
Figure 2. An MMN with one HoA and multiple CoAs
4. Impact Analysis
To implement the above operations on MMNs, the impacts to the
existing protocols are analyzed.
4.1 An MMN with multiple HoAs and multiple CoAs
To implement the low power operation of an MMN with multiple HoAs and
multiple CoAs described in Section 3.1, the requirements are similar
to the Section 6.2.2 in [5] that presents the requirements to use one
HoA as a CoA and its implementation based on the current mobile IPv6
[3]. However, an MMN should implement its own power management scheme
to decide which and the number of interfaces to sleep and to wake up,
and the time to wake up and to sleep. That is an implementation issue.
4.2 An MMN with one HoA and multiple CoAs
To implement the operation of an MMN with one HoA and multiple CoAs
described in Section 3.2, the requirements are described in the
Section 6.2.1 in [5] that presents the requirements to bind multiple
CoAs to a given HoA. Unfortunately, the MIPv6 specification does not
support this function currently. Besides the requirements to bind
multiple CoAs to a given HoA, the priorities or the preferences of
the CoAs that packets should be forwarded to should be carried in the
binding update or other MIP messages and extensions such as [6].
Moreover, an MMN should implement its own power management scheme to
decide which and the number of interfaces to sleep and to wake up,
and the time to wake up and to sleep. That is also an implementation
issue.
5. Summary and Future Work
The draft suggested to use multiple care-of addresses and/or home
addresses for an MMN in order to save the power consumption of a
mobile with multiple interfaces. Two usage scenarios are presented to
demonstrate the benefits of the design. The impact analysis shows
that the extension of the existing mobile IPv6 is required and needs
to be further designed to support this feature.
Security Considerations
Security concerns should be further studied.
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References
1.J. Manner and M. Kojo, "Mobility Related Terminology," RFC 3753,
June 2004.
2. T. Ernst, N. Montavont, R. Wakikawa, E. Paik, C. Ng, K.
Kuladinithi, and T. Noel, "Goals and Benefits of Multihoming,"
Internet-Draft, draft-ernst-generic-goals-and-benefits-01, Feb. 2005.
3. D. Johnson, C. Perkins, and J. Arkko, "Mobility Support in IPv6,"
RFC 3775, June 2004.
4. C. Ng, E. Paik, T. Ernst, and M. Bagnuloet,"Analysis of
Multihoming in Network Mobility Support," Internet-Draft, draft-ietf-
nemo-multihoming-issues-03, July 2005.
5. N. Montavont, R. Wakikawa, T. Ernst, C. Ng, and K. Kuladinithi, "
Analysis of Multihoming in Mobile IPv6," Internet-Draft, draft-
montavont-mobileip-multihoming-pb-statement-04.txt, June 2005.
6. Ryuji Wakikawa, Keisuke Uehara, Thierry Ernst, and Kenichi Nagami,
"Multiple Care-of Addresses Registration," Internet-Draft, draft-
wakikawa-mobileip-multiplecoa-04.txt, June 2005.
Author's Addresses
Shiao-Li Tsao
Department of Computer Science,
National Chiao Tung University
EC426, 1001 Ta Hsueh Road, Hsinchu, Taiwan 300, ROC
Phone: +886-3-5712121 ext. 54717
Email: sltsao@cs.nctu.edu.tw
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Copyright (C) The Internet Society (2005). This document is subject
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except as set forth therein, the authors retain all their rights.
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