Internet DRAFT - draft-hong-multipleif-mn-pb-statement
draft-hong-multipleif-mn-pb-statement
Network Working Group Y-G. Hong
Internet-Draft J-C. Lee
Expires: April 17, 2006 J-S. Park
H-J. Kim
ETRI
October 16, 2005
Analysis of multiple interfaces in a Mobile Node
draft-hong-multipleif-mn-pb-statement-00
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Copyright (C) The Internet Society (2005).
Abstract
This document is an analysis of multiple interfaces in a mobile node
using Mobile IPv6 or a mobile router using NEMO Basic Support. The
current Mobile IPv6 and NEMO Basic Support are suitable for a single
network interface. When a mobile node or a mobile router has
multiple interfaces, the current Mobile IPv6 and NEMO Basic Support
cannot directly be used for them. In this document, we describe some
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problems for a mobile node which has multiple network interfaces when
the mobile node is using Mobile IPv6 as an aspect of a node.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statements . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Mobile IPv6-specific Issues . . . . . . . . . . . . . . . 4
2.2. General Network Issues . . . . . . . . . . . . . . . . . . 4
2.3. Considerations for Heterogeneous Environments . . . . . . 6
3. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Normative References . . . . . . . . . . . . . . . . . . . 8
4.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Introduction
In future ubiquitous networks, many services and many access
technologies are expected to be interworked and harmonized for better
services. To do so, a mobile node must have different access
technologies and different network interfaces for each access
technology [3].
Mobile IPv6 [1] and NEMO Basic Support [2] can solve the problem of
the change of IPv6 network address when a mobile node or a mobile
router moves. But these protocols are developed for a mobile node
with a single network interface and a mobile router with a single
egress network interface. We can not directly use Mobile IPv6 for a
mobile node with multiple network interfaces [4,5]. This document
describes the problems of multiple interfaces in a mobile node as an
aspect of a node.
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2. Problem Statements
2.1. Mobile IPv6-specific Issues
In Mobile IPv6, a mobile node knows its network movement by comparing
the prefix information, which is included in the latest arrived
Router Advertisement messages, with the prefix information, which is
stored in locally or using other ways [6]. The operations required
for handover such as Binding update or Binding Acknowledgement
happens only after a mobile node determines the movement to different
networks.
To determine network movement, a mobile node carefully observes the
received Router Advertisement messages from routers through one
specific network interface. Usually, the specific network interface
is selected when Mobile IPv6 module starts. In this case, the mobile
node is focusing on only that network interface to detect movement.
Router Advertisement messages that came from other network interfaces
do not affect the operations of the mobile node (determination of
movement detection) if the mobile node has multiple network
interfaces and it observe only one specific network interface.
When we apply Mobile IPv6 and the implementation of Mobile IPv6 code
(HUT MIPL) [7] to a mobile node which has multiple network
interfaces, we must consider Router Advertisement messages which are
delivered through all network interfaces, not only the specific
network interface, which is selected when Mobile IPv6 module start.
When a mobile node has multiple network interfaces, a mobile node
must have the ability to look at all Router Advertisement messages
from different network interfaces because Router Advertisement
messages may be delivered from different network interfaces.
2.2. General Network Issues
The primary purpose of Mobile IPv6 or NEMO Basic Support is to
maintain a communication session even though the IPv6 address of a
mobile node or a mobile router has changed when the mobile node or
the mobile router moves. As an application layer's view or socket
layer's view, the address of a mobile node (Home Address) is not
changed nevertheless the Care of Address is changed. This rule must
also be applied when multiple network interfaces are used in a mobile
node.
The problem of multiple network interfaces in a mobile node is the
relation between a destination address and a network interface. In
the following case, we assume a mobile node with two network
interfaces I1 and I2 of different access technologies. Each
interface is configured with a global IPv6 address, respectively IP1
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and IP2, and the address of a correspondent node is IP3.
_________
| CN |
|_________|
| IP3
/|\
+------------------+ +------------------+
| Network 1 (N1) | | Network 2 (N2) |
| | | |
+------------------+ +------------------|
Interface 1 (I1) \|/ \|/ Interface 2 (I2)
IP1 | | IP2
|_________|
| MN |
|_________|
Figure 1. A mobile node with two interfaces
| Location |(Source Address, |Relation btw a Destination|
|(Used I/F)| Destination Address) | Addr. and a network I/F |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| N1 (I1) | (IP1, IP3) | IP3 -> I1 |
| N2 (I2) | (IP2, IP3) | IP3 -> ? |
Figure 2. Relation between destination address and network
interfaces
The mobile node uses Mobile IPv6 when it moves between networks.
Before moving, when the mobile node uses (I1, IP1) and sends packets
to a correspondent node, the source address and destination address
of packets is (IP1, IP3) and the used network interface is I1. If
the mobile node moves other network N2, and then the mobile node uses
(I2, IP2) and the used network interface is I2. Before moving, the
destination address (IP3) of the correspondent node is mapped to a
network interface I1. After moving, when an application tries to
send packets to the correspondent node, it continually tries to use a
network interface I1 if the relation of destination address IP3 and
network interface I1 is not updated properly. If this situation
happens, even though, the network interface is changed to I2, packets
are delivered to I1. The communication sessions will be disrupted.
To solve this problem, a mobile node must update the relation between
a destination address and a network interface when it changes a
network interface.
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2.3. Considerations for Heterogeneous Environments
If a mobile node moves between networks with a single network
interface, the change may be only a network address. Because the
mobile node has an access technology of the single network interface,
it doesn't need to consider other aspects such as the change of
access technologies and IP version.
If a mobile node moves between networks with multiple network
interfaces, other changes may happen. If a mobile node has
heterogeneous network interfaces (one is a WLAN interface and the
other is a CDMA interface), changes include the network address,
network interface and access technologies of the selected network
interface after moving. Currently in Korea, we can use IPv6 based
WLAN service but it is impossible to use IPv6 based CDMA service.
The deployment of IPv6 based CDMA service will be done sooner or
later. Until the deployment of IPv6 based CDMA service occur, if we
want to use Mobile IPv6 or NEMO Basic Support with a CDMA network
interface, we must consider how to use Mobile IPv6 or NEMO Basic
Support in IPv4 based CDMA network.
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3. Conclusions
Multihoming of a mobile node or a mobile router is an important issue
as described in [3]. When a mobile node has multiple interfaces, the
mobile node can use heterogeneous network interfaces and it can
provide ubiquitous access. In this document, we showed the issues
when a mobile node or a mobile router has multiple network interfaces
as an aspect of a node. If a mobile node and a mobile router have
multiple network interfaces, the mobile node and the mobile router
must have the ability to look at all Router Advertisement messages
from different network interfaces. Also the mobile node and the
mobile router must update dynamically the relation of a destination
address of a correspondent node and a network interface after the
change of a network interface. Because the mobile node may use
heterogeneous access technologies, some access networks of a selected
network interface do not support IPv6. In this case we must consider
how to support Mobile IPv6 and NEMO Basic Support in IPv4 based
networks.
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4. References
4.1. Normative References
[1] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004.
[2] Devarapalli, V., Wakikawa, R., Petrescu, A. and Thubert, P.,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005.
4.2. Informative References
[3] Ernst, T., Montavont, N., Wakikawa, R., Paik, E., and K.
Kuladinithi, "Goals and Benefits of Multihoming",
draft-ernst-generic-goals-and-benefits-01 (work in
progress), February 2005.
[4] Montavont, N., Wakikawa, R., Ernst, T., Ng, C-W., and K.
Kuladinithi, "Analysis of Multihoming in Mobile IPv6",
draft-montavont-mobileip-multihoming-pb-statement-04
(work in progress), June 2005.
[5] Montavont, N., Noel, T. and Kassi-Lahlou, M., "Mobile IPv6
for multiple interfaces (MMI)", draft-montavont-mip6-mmi-
02.txt (work in progress), July 2005.
[6] Choi, J. and Nordmark, E., "DNA with unmodified routers:
Prefix list based approach", draft-ietf-dna-cpl-01.txt
(work in progress), April 2005.
[7] MIPL Mobile IPv6 for Linux, http://www.mobile-ipv6.org
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Authors' Addresses
Yong-Geun Hong
ETRI
161 Gajeong-dong Yuseong-gu
Daejeon, 305-350
Korea
Phone: +82 42 860 6557
Email: yghong@etri.re.kr
Joo-Chul Lee
ETRI
161 Gajeong-dong Yuseong-gu
Daejeon, 305-350
Korea
Phone: +82 42 860 1021
Email: rune@etri.re.kr
Jung-Soo Park
ETRI
161 Gajeong-dong Yuseong-gu
Daejeon, 305-350
Korea
Phone: +82 42 860 6514
Email: pjs@etri.re.kr
Hyoung-Jun Kim
ETRI
161 Gajeong-dong Yuseong-gu
Daejeon, 305-350
Korea
Phone: +82 42 860 6576
Email: khj@etri.re.kr
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