autoconf Working Group Jaehwoon Lee
Internet Draft Dongguk University
Expires: January 6, 2009 Sanghynn Ahn
University of Seoul
Younghan Kim
Soongsil University
Yuseon Kim
Sangeon Kim
KT
July 7, 2008
Address Autoconfiguration for the subordinate MANET with Multiple MBRs
draft-jaehwoon-autoconf-mmbr-00.txt
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Internet-Draft Address Autoconfiguration for multiple MBRs July 7, 2008
Abstract
In order to allow the subordinate MANET to be connected to the
external network, the MANET border router (MBR) has been defined. For
providing scalability and reliability to the subordinate MANET,
multiple MBRs may be deployed. One of the issues on the subordinate
MANET with multiple MBRs is which network prefixes are to be
advertised by MBRs. In the case when MBRs advertise different network
prefixes, if a MANET node changes its default MBR to a new one, the
node may have to transmit packets via non-optimal paths to keep using
the existing connection to the previous MBR, or change its address by
using the network prefix information from the new MBR. In the latter
case, on-going sessions can be terminated because of the address
change. In this draft, we define a PMIPv6 based address
autoconfiguration mechanism that enables MANET nodes to operate
properly when all MBRs advertise the same network prefix in the
subordinate MANET.
Table of Contents
1. Introduction..................................................3
2. Terminology...................................................4
3. Message format................................................4
3.1 Registration Request message..............................4
3.2 Registration Confirmation message.........................4
4. Protocol operation............................................4
5. Security Considerations.......................................6
6. IANA Considerations...........................................6
References.......................................................6
Author's Addresses...............................................7
Intellectual Property and Copyright Statements ..................8
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1. Introduction
The mobile ad hoc network (MANET) enables mobile nodes to communicate
via multiple wireless hops without the need of any wired
infrastructure. In a MANET, two nodes not within their transmission
range have to deliver data to each other through other intermediate
nodes. For forwarding packets destined to other nodes, each node must
have the routing capability, i.e., the mechanism for establishing
data delivery routes between any pair of source and destination
nodes. The IETF MANET working group has defined route setup
mechanisms for delivering data between MANET nodes. Especially for an
ad hoc network such as the MANET, the mechanism that can allow
nodes to configure their addresses autonomically is more desirable
than the static address configuration mechanism since the former has
less configuration and management overhead by not incurring manual
intervention.
The MANET can be classified into the subordinate MANET or the
autonomous MANET depending on whether it is connected to the external
network or not[1]. The MANET border router (MBR) which is a gateway
device connecting the MANET with the external network has been
defined for the subordinate MANET. As the number of nodes in the MANET
increases, the amount of traffic between the MANET and the Internet
increases, so the MBR gets overloaded, resulting in the overall
network performance degradation. To overcome this problem, multiple
MBRs can be used for the Internet connectivity [2]. Mechanisms in
which each MBR advertises a different network prefix have been
proposed for the MANET with multiple MBRs[3-4]. However, in these
mechanisms, if a node moves to another place, it sends packets via
non-optimal paths to maintain its connection to the previous MBR, or
it changes its address by using the network prefix from the new MBR.
In the latter case, an on-going session may get terminated because
of the address change.
In this draft, we define a PMIPv6 based address autoconfiguration
mechanism that enables MANET nodes to operate properly in the case
when all MBRs advertise the same network prefix.
2. Terminology
TBD.
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3. Message Format
3.1 Registration Request (RR) Message
TBD
3.2 Registration Confirmation (RC) Message
TBD
4. Protocol Operation
MR MBR1(MAG1) MBR2(MAG2) LMA (internet) CN
| | | | |
|<----------| | | |
|SMF message| | | |
(Configure IPv6 address to MANET interface) | |
|<--------->| | | |
(DHCP with prefix delegation) | | |
|---------->| | | |
|RR message | | | |
| |---------------------------------->| |
| | PBU message (Create Binding Cache Entry) |
| |<----------------------------------| |
| | PBAck message | |
|<----------| | | |
|RC message | | | |
|<--------->|<=================================>|<------------>|
| Data packet transfer between MR and CN via MBR1 and LMA |
(MR changes its default gateway from MBR1 to MBR2) | |
|<---------------------------| | |
| SMF message | | |
|--------------------------->| | |
| RR message | | |
| | |----------------->| |
| | | PBU message | |
| | | (Update Binding Cache Entry |
| | |<-----------------| |
| | | PBAck message | |
|<---------------------------| | |
| RC message | | |
|<-------------------------->|<================>|<------------>|
| Data packet transfer between MR and CN via MBR2 and LMA |
| | | | |
Figure 1: Message exchange scenario
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The message exchange procedure among network components considered
in this draft is shown in figure 1. The network is composed of an
external network such as the global Internet, a PMIPv6 domain and a
MANET. In the PMIPv6 network, there exists a local mobility
anchor (LMA) which acts like a home agent (HA) within the PMIPv6
domain[5]. The MANET is connected to the PMIPv6 domain by using
multiple MBRs, and each MBR acts as a mobility access gateway (MAG)
within the PMIPv6 domain. To the MANET, a single network prefix is
assigned, and each MBR periodically advertises the same network
prefix and the IPv6 address assigned to its MANET interface by using
the simplified multicast forwarding (SMF) message defined in [6].
SMF messages transmitted by MBRs have the same network prefix and
the prefix length.
A MANET node consists of a MANET router (MR) and (virtual) hosts[7].
A MR has a MANET interface for connecting to the MANET and a host
interface for connecting to hosts. When a MR connects to the MANET
for the first time, it waits for SMF messages from MBRs for some time
duration which is determined by a given timer value. If the MR
receives SMF messages from multiple MBRs, it selects the MBR which
can be reached via the minimum number of hops. If more than one MBRs
can be reached via the minimum hops, it selects one at random or
based on some other metrics. Let the MBR firstly chosen by the MR be
MBR1. The MR configures the IPv6 address of its MANET interface by
using the stateless address autoconfiguration mechanism based on the
network prefix included in the SMF message from MBR1 and its MAC
address, and sets MBR1 as its default gateway. Then, the MR obtains
a network prefix by using the DHCP with prefix delegation.
The MR with the delegated network prefix allocates an IPv6 address
belonging to the delegated network prefix to the hosts connected to
itself. Also, the MR sends a Registration Request (RR) message with
the delegated network prefix information to MBR1. The format of the
RR message is defined in the section 2. From the received RR message,
MBR1 stores the binding information of the network prefix and the
address assigned to the MANET interface of the MR, and sends a proxy
binding update (PBU) message to the LMA. Then, the LMA stores the
binding information of the received network prefix and the MBR1
address. The packets from hosts in the external network to the hosts
connected to the MR are delivered to the LMA, first, and, then, the
LMA forwards the received packets to MBR1 via the tunnel, and then,
MBR1 forwards them to the MR.
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If the MR moves and receives a SMF message which has been broadcast
by another MBR (i.e., MBR2) and the difference between the number of
hops from MBR1 and that from MBR2 is larger than a given threshold,
the MR changes its default gateway address information from MBR1 to
MBR2. After that, the MR sends a RR message to MBR2. Upon receiving
the RR message, MBR2 stores the binding information of the network
prefix and the IPv6 address assigned to the MANET interface of the
MR, and sends a PBU message to the LMA. Upon receiving the PBU
message, the LMA changes the binding information of the network
prefix information in the PBU message from MBR1 to MBR2. Then, the
packets from hosts in the external network to the MR are delivered
to MBR2 via the LMA through the tunnel. And, MBR2 forwards the
received packets to the MR.
5. Security Consideration
TBD.
6. IANA Considerations
TBD.
References
[1] E. Baccelli et al., "Address Autoconfiguration for MANET:
Terminology and Problem Statement", draft-ietf-autoconf-
statement-04, Work in progress, Feb. 2008.
[2] S. Ruffino, P. Stupar and T. Clausen, "Autoconfiguration in a
MANET: connectivity scenarios and technical issues", draft-
ruffino-manet-autoconf-scenarios-00, work in progress, Oct. 2004.
[3] S. Ruffino and P. Stupar, "Automatic configuration of IPv6
addresses for MANET with multiple gateways (AMG)",
draft-ruffino-manet-autoconf-multigw-03, work in progress,
June 2006.
[4] C. Jelger, T. Noel and A. Frey, "Gateway and address
autoconfiguration for IPv6 adhoc networks", draft-jelger-manet-
gateway-autoconf-v6-02, work in progress, apr. 2004.
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[5] S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury and
B. Patil, "Proxy Mobile IPv6", draft-ietf-netlmm-proxymip6-18,
work in progress, May 2008.
[6] J. Macker, "Simplified Multicast Forwarding for MANET",
draft-ietf-manet-smf-07, Work in progress, Feb. 2008.
[7] I. Chakeres, J. Macker and T. Clausen, "Mobile Ad hoc Network
Architecture", draft-ietf-autoconf-manetarch-07,
Work in progress, Nov. 2007.
Author's Addresses
Jaehwoon Lee
Dongguk University
26, 3-ga Pil-dong, Chung-gu
Seoul 100-715, KOREA
Email: jaehwoon@dongguk.edu
Sanghyun Ahn
University of Seoul
90, Cheonnong-dong, Tongdaemun-gu
Seoul 130-743, KOREA
Email: ahn@uos.ac.kr
Younghan Kim
Soongsil University
11F Hyungnam Engineering Bldg. 317, Sangdo-Dong,
Dongjak-Gu, Seoul 156-743 Korea
E-main: yhkim@dcn.ssu.ac.kr
Yuseon Kim
KT
17 Woomyeon-dong, Seocho-gu
Seoul 137-792, KOREA
Email: yseonkim@kt.co.kr
Sangeon Kim
KT
17 Woomyeon-dong, Seocho-gu
Seoul 137-792, KOREA
Email: sekim@kt.co.kr
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