No Specific Working Group K. Nagami
Internet-Draft INTEC NetCore
Expires: November 16, 2007 S. Uda
JAIST
N. Ogashiwa
INTEC NetCore
H. Esaki
U. Tokyo
R. Wakikawa
Keio University
H. Ohnishi
NTT
May 15, 2007
Multi-homing for small scale fixed network Using Mobile IP and NEMO
draft-nagami-mip6-nemo-multihome-fixed-network-04.txt
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Abstract
Multi-homing technology improves the availability of host and network
connectivity. Since the node and network behavior of mobile
networking and fixed networking are different, the different
architecture has been discussed and proposed. This document proposes
the common architecture both for mobile and fixed networking
environment, using the mobile IP [1] and NEMO [2]. The proposed
architecture only requires a modification of the mobile IP and NEMO
so that multiple-CoA can be used. In addition, multiple HAs which
are located in different place, are required for redundancy.
1. Motivation
Users of small-scale network need to improve the network availability
and to get load balance of several links by easy method. Multi-
homing technology is one of solutions to improve the availability.
Conventional major multi-homing network uses BGP. But it has some
issues. Therefore, we propose a multi-homing architecture using the
mobile IP and NEMO for small-scale fixed network.
1.1. General Benefits of Multi-homing
In a multi-homing network environment, both users and network
managers takes several benefits by controlling out-going traffic, in-
comming traffic or both of them. Those benefits are listed in the
draft [3] as the goals and benefits of multi-homing. The following
is a summary of those goals and benefits listed in the draft.
o Ubiquitous Access
o Redundancy/Fault-Recovery
o Load Sharing
o Load Balancing
o Bi-casting
o Preference Settings
1.2. Problems to be Solved to Accomplish Multi-homing
Several multi-homing technologies have been proposed so far.
Conventional major multi-homing network uses BGP. But it has some
issues as follows.
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(1) Increasing route entries in the Internet
In the multi-homing environments, each user's network needs to
advertise its address block to all ISPs connected to them. If
multi-homed user connects only one ISP, the ISP can advertise
routing information to aggregate them. But some multi-homed user
needs to connect with different ISPs in preparation for failure of
ISP. In this case, ISPs need to advertise routing information for
multi-homed user without aggregation. Therefore, the number of
routing entries in the Internet is increasing one by one.
(2) Difficulty to efficiently use multiple links
It is not easy to control in-coming traffics in the case of the
conventional multi-homing architecture using BGP. Therefore, load
balancing of connected links is difficult.
1.3. Using the Architecture of Mobile IP and NEMO to Solve the Problems
Basically, the Mobile IP and the NEMO have been proposed for mobile
host or mobile network, however the architecture and the protocol of
them can be used for fixed networks. The following problems
mentioned avobe can be solved by using the architecture and the
protocol of them. The details of the solution is being described in
the later section.
o increasing route entries in the Internet
o difficulty to efficient use multiple links
Moreover, by using the architecture and the protocol of the MIP and
the NEMO, a cost of network operation will be decreased. For
instance, in the architecture of the MIP and the NEMO, renumbering IP
addresses when relocation of an office or network equipments becomes
needless in consequence of that the network address prefix used in a
user network in a Mobile IP environment is not depend on the upstream
ISP's network prefix.
2. Multi-homing Architecture Using Mobile IP and NEMO
2.1. Mobile Network Includes Fixed Network
NEMO and Mobile IP must work with multi-homing by its nature. This
is because mobile nodes need to use multiple links for improving the
availability of network connectivity since the wireless link is not
always stable. Therefore, we propose that multihoming for fixed
nodes (routers and hosts) use the framework of NEMO and Mobile IP.
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2.2. Overview multi-homing network architecture using Mobile IP
Figure 1 shows basic multi-homing network architecture. In this
architecture, a mobile router (MR), which is boarder router of multi-
homed network, sets up several tunnels between the MR and the HA by
multiple-CoA registration. A HA or a router which the HA belongs
advertise user's network prefix (Prefix X in Fig.1) to ISPs via
routing protocol. If HA has several multi-homed network (Prefix X
and Y in Fig.1), they can advertise an aggregated network prefix to
ISPs. Therefore, the Internet routing entries do not increase one by
one when multi-homed user is increased.
HA1
||(Advertise aggregated prefix X and Y)
|v
ISP
|
+------------------------+---------------------+
| The Internet |
+-+----------+--------------------+----------+-+
| | | |
ISP-A ISP-B ISP-A' ISP-B'
| | | |
| | | |
+--- MR ---+ +--- MR ---+
CoA1 | CoA2 CoA1|CoA2
| |
-------+--------- (Prefix X) -------+------ (Prefix Y)
Multihomed Network X Multihomed Network Y
Figure 1: advertisement of aggregated prefixes
Packets to multi-homed users go to HA and the HA sends packets to MR
using CoA1 and CoA2. The HA selects a route which CoA is used. The
route selection algorithm is out of scope of this document. This can
improve availability of user network and control an in-coming traffic
between ISP and MR. In the basic architecture, HA1 is single point
of failure. In order to improve availability of user network,
multiple HA is needed. This is described in later section.
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HA1
^ | |
(1) Packets to prefix X | | | (2) HA forwards the packets
are sent to HA | | v to CoA1 or CoA2
+-------+------+
| The Internet |
+-+----------+-+
| |
| | |(3) packets are forwarded over
| | | the MIP tunnel selected by
| | v the HA1
ISP-A ISP-B
| | |
| | |
+--- MR ---+ v
CoA1 | CoA2
|
-------+--------- (Prefix X)
Multihomed Network A
Figure 2: packet forwarding by HA
3. Requirements for Mobile IP and NEMO
3.1. Multiple Care-of-Addresses (CoA)
Multiple Care-of-Addresses needs to improve the availability and to
control in coming and out going traffic. The current Mobile IPv6 and
the NEMO Basic Support protocol does not allow to register more than
one care-of address bound to a home address to the home agent.
Therefore, [4] is proposed to extend the MIP6 and the NEMO Basic
Support to allow multiple care-of address registrations for the
particular Home Address.
3.2. Multiple Home Agents
Multiple Home Agents should be geographically distributed across the
Internet, for the improvement of service availability and for the
load balancing of HA. When all the networks that have HA advertise
the same network prefix to their adjacent router/network, the traffic
is automatically routed to the nearest Home Agent from the view point
of routing protocol topology. This operation has been already proven
operational technology in the area of web server application, such as
CDN (Contents Delivery Network), regarding IGP and EGP.
In order to operate multiple HAs, all HAs must have the same
information such as binding information. This is the synchronization
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of database among the HA. The HAHA protocol [5] introduces the
binding synchornozation among HAs. This is the same architecture as
I-BGP. The database is synchronized by full-mesh topology. In
addition, in order to simplify operation of HA, the database is
synchronized using star topology. This is analogy with I-BGP route
reflector.
sync
HA1 ------ HA2
| |
+-+----------+-+
| The Internet |
+-+----------+-+
| |
ISP-A ISP-B
| |
| |
+--- MR ---+
CoA1 | CoA2
|
-------+---------
Multihomed Network
Figure 3: Architecture with HA redundancy
4. Discussion on the Mailing List
4.1. Why does the proposed architecture use NEMO protocols
The multihome architecture proposed in this draft is basically same
as the architecture of NEMO. Furthermore, NEMO protocols meet to
requirements of the proposed architecture in this draft, which are:
o protocol can inform CoA, HoA, BID from MR to HA
o protocol can establish multiple tunnels between MR and HA
o protocol support multiple HA and can synchronize Binding Caches
among multiple HAs
The proposed multihome architecture uses NEMO protocols as one of
applications of NEMO. Needless to say, using NEMO protocol is one of
solutions to accomplish the proposed multihome architecture. Another
solution is to propose a new protocol just like NEMO. Nevertheless,
such new protocol will have functions just same as NEMO.
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4.2. Route Announcement from Geographically Distributed Multiple HAs
In proposed architecture, xSP (Multihome Service Provider) is
introduced. xSP is a conceptual Service Provider and it doesn't have
to be connected to the Internet physically for all practical purpose.
xSP has one or more aggregatable mobile network prefixes. xSP
contracts with some ISPs that are physically connected to the
Internet. The purpose of this contract is to setup some HAs into
those ISP's network. Those HAs announce the xSP's aggregated mobile
network prefixes. This means that HAs work just like border gateway
router, and this situation is same as peering between ISP and xSP.
In this case, origin AS announced from HAs is xSP.
On the other hand, multihome user (small office user or home user)
contract with xSP to acquire a mobile network prefix from xSP. Each
multihome user has a MR and multiple L3 connectivity to the Internet
via multiple ISPs and the MR will establish multiple tunnels to HA.
Since user's mobile network prefixes are aggregated and announced
from HA, packets to user's mobile network will be sent to nearest HA
depending on global route information at that time and HA that
received such packets forward those packets to user's network over
the established multiple tunnels.
This model of route announcement from multiple HA is along with the
conventional scalable Internet architecture and it doesn't have
scalability problems.
5. Implementation and Experimentation
We have implemented and experimented the proposed architecture.
Currently, the system works well not only on our test-bed network,
but on the Internet. In our experimentation, MR has two upstream
organizations (ISPs) and two Care-of-Addresses for each
organizations. The MR uses multiple-CoA option to register the Care-
of-Addresses to HA.
6. Security considerations
This document describes requirements of multiple CoAs and HAs for
redundancy. It is necessary to enhance the protocol of the MIP and
the NEMO to solve the requirements. Security considerations of these
multihoming network must be considered in a specification of the each
protocol.
7. References
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7.1. 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 P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005.
7.2. Informative References
[3] Ernst, T., Montavont, N., Wakikawa, R., and E. Paik, "Goals and
Benefits of Multihoming",
draft-multihoming-generic-goals-and-benefits (work in progress),
February 2004.
[4] Wakikawa, R., Ernst, T., and K. Nagami, "Multiple Care-of
Addresses Registration", draft-ietf-monami6-multiplecoa-02 (work
in progress), February 2007.
[5] Wakikawa, R., Thubert, P., and V. Devarapalli, "Inter Home
Agents Protocol Specification",
draft-wakikawa-mip6-nemo-haha-spec-01 (work in progress),
March 2006.
Authors' Addresses
Kenichi Nagami
INTEC NetCore Inc.
1-3-3, Shin-suna
Koto-ku, Tokyo 135-0075
Japan
Phone: +81-3-5565-5069
Fax: +81-3-5565-5094
Email: nagami@inetcore.com
Satoshi Uda
Japan Advanced Institute of Science and Technology
1-1 Asahidai
Tatsunokuchi, Ishikawa 923-1292
Japan
Email: zin@jaist.ac.jp
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Nobuo Ogashiwa
INTEC NetCore Inc.
1-3-3, Shin-suna
Koto-ku, Tokyo 135-0075
Japan
Email: ogashiwa@inetcore.com
Hiroshi Esaki
The university of Tokyo
7-3-1 Hongo
Bunkyo-ku, Tokyo 113-8656
Japan
Email: hiroshi@wide.ad.jp
Ryuji Wakikawa
Keio University
Department of Environmental Information, Keio University.
5322 Endo
Fujisawa, Kanagawa 252-8520
Japan
Phone: +81-466-49-1100
Fax: +81-466-49-1395
Email: ryuji@sfc.wide.ad.jp
URI: http://www.wakikawa.org/
Hiroyuki Ohnishi
NTT Corporation
9-11, Midori-Cho, 3-Chome
Musashino-Shi, Tokyo 180-8585
Japan
Email: ohnishi.hiroyuki@lab.ntt.co.jp
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