Global Standardization Activities

Standardization Trends of IP Mobility
Technologies
Toshihiko Tamura†, Hiroyuki Ohnishi, Takeshi Ogawa,and Yasushi Takagi
Abstract
This article introduces current standardization trends of Mobile IPv6. This is one of the leading IP(Internet protocol) mobility technologies, which aim to achieve seamless communication independent ofthe access medium in order to achieve ubiquitous communication.

1. Overview of Mobile IPv6
One of the leading IP (Internet protocol) mobility
technologies is Mobile IPv6, which supports terminal
mobility. It will enable terminals to maintain communication even if the terminal changes its IP address bymoving to another network or changing access medium such as WiFi or 3G (third-generation) mobile. It
has three main features. First, it provides a location
information management function in the IP layer
between a fixed IP address (the home address (HoA))
and the IP address of the current location (the care-ofaddress (CoA)), which changes. Second, it enables
mobile nodes to communicate securely by IPv6 IPsec(IP security protocol) between a home agent (HA)
and mobile node (MN). Third, it provides route optimization between a correspondent node (CN) andMN. Since the basic operation of Mobile IPv6 wasdescribed in the July 2004 issue of this magazine [1],we do not explain it here. Mobile IPv6 can work on
an IPv6 network, and its deployment will be accelerated by progress in IPv6 development.
2. Trends of IP mobility technologies in IETF
IP mobility technologies including Mobile IPv6 arecurrently being studied in the Internet Engineering
Task Force (IETF) [2], which is a standardization† NTT Network Service Systems Laboratories
Musashino-shi, 180-8585 Japan
E-mail: tamura.toshihiko@lab.ntt.co.jp

90organization for Internet technologies. IETF holds
technical discussions in various Working Groups(WGs). The WGs related to IP mobility include
Mobility for IPv6 (mip6), Mobility for IPv4 (mip4),
Network Mobility (nemo), MIPv6 Signaling andHandoff Optimization (mipshop), and IKEv2 Mobility and Multihoming (mobike). Besides these WGs, aBirds of a Feather (BOF) session is sometimes held at
an IETF meeting for market research or technicalbrainstorming, but it does not have the status of aWG. Some BOF sessions have been held to discuss
preliminary new IP mobility technologies. The nextsection describes the latest standardization trends ofIP mobility studied in the WGs and BOF shown in
Table 1.
2.1 Mobility for IPv6 WG (mip6)
Although Mobile IPv6 was an Internet-Draft for along time, it finally got prescribed by an RFC(request for comments) in June 2004. The basic operation of Mobile IPv6 is prescribed by RFC 3775(“Mobility support in IPv6”) and the IPsec specification between HA and MN is prescribed by RFC 3776(“Using IPsec to Protect Mobile IPv6 Signaling
between Mobile Nodes and Home Agents”). Currently this WG is mainly discussing items for achieving
Mobile IPv6 services, especially bootstrapping technology, which provides automatic configuration forusing Mobile IPv6 services, and collaboration
between AAA (authentication, authorization, andaccounting) and HA. Other major discussion items
include reliability improvements for HAs and renumNTT Technical Review

Global Standardization Activities

Table 1. Progress of IP mobility standardization in IETF WGs and BOF.
Overview

Main RFC

Main discussion items

mipv6 WG

Study of Mobile IPv6 supporting terminal
mobility of IPv6 mobile node

RFC 3775
RFC 3776

Bootstrapping solution, collaboration betweenHA and AAA, and support of IKEv2

mipshop WG

Study of optimization of signaling andhandover for Mobile IPv6

RFC 4068
RFC 4140

Fast handover over IEEE 802.11 wireless LANnemo WG

Study of network mobility with extensionof Mobile IPv6

RFC 3963

Multihoming and network mobility for IPv4/IPv6
dual networks

mobike WG

Study of applicability for mobility andmultihoming with extension of Mobile IPv6—

Prescribing of mobike protocol and IP address
exchange method with PFKEY extension

mip4 WG

Study of Mobile IPv4 supporting terminal
mobility of IPv4 mobile node

RFC 3220(prescribed in theformer mobileip WG)

NAT traversal for the Mobile IPv4 network
environment and cooperation between Mobile
IPv4 and VPNs

netlmm BOF
dna WG
mobopts RG

Study of methods for providing local mobility
without additional function to the terminal
Study of decreasing setup time of IPv6
address at handoverResearch on handover

bering on home links.
2.2 MIPv6 Signaling and Handoff Optimization
WG (mipshop)
The main discussion items of this WG are seamless
handover and hierarchical Mobile IPv6 as an extension of Mobile IPv6. Seamless handover was prescribed by RFC 4068 (“Fast Handover for MobileIPv6) in July 2005 and by hierarchical Mobile IPv6 as
RFC 4140 (“Hierarchical Mobile IPv6 MobilityManagement”) in August 2005. The category of both
RFCs is experimental. Currently, this WG is mainly
discussing fast handover over an IEEE 802.11 wireless LAN (local area network).
2.3 Network Mobility WG (nemo)
Network mobility, which enables networks to move
while communicating, is an extension of Mobile
IPv6. Its basic operation is prescribed by RFC 3963(“Network Mobility Basic Support Protocol”). Currently, this WG is mainly discussing multihomingand network mobility for IPv4/IPv6 dual networks.
2.4 IKEv2 Mobility and Multihoming WG(mobike)
The dynamic key exchange protocol known as
Internet key exchange version 2 (IKEv2) was studied
in the former ipsec WG and was on the waiting list tobecome an RFC in August 2005. Mobike technology
is an extension of IKEv2. When a link is set up again
with IP address changes in the case of mobility or
multihoming, this technology enables endpoints toVol. 3 No. 12 Dec. 2005—
RFC 4135—

Clarification of the requirements
Method of detecting handover in layer 3 incollaboration with layer 2
Muticast handover

use the current security association (SA) without rekeying and re-authentication. However, Mobike supports the mobility of only one endpoint, while Mobile
IPv6 supports the mobility of both endpoints. Forinstance, Mobike enables a remote access VPN (virtual private network) user to move from one address
to another while keeping the connection with theVPN gateway active. Currently, this WG is mainly
discussing requirements of Mobike.
2.5 Mobility for IPv4 WG (mip4)
This WG discusses Mobile IPv4 running on an
IPv4 network. The basic operation of Mobile IPv4
was prescribed by RFC 3220 (“Mobility Support inIPv4”) in the former mobileip WG, which was activefrom 1992 to July 2003, as the predecessor of mip6,mip4, and mipshop WG. Currently, this WG is mainly discussing NAT (network address translation) traversal for the Mobile IPv4 network environment andcooperation between Mobile IPv4 and VPNs.
2.6 Other WGs and BOF
A Network-based Localized Mobility Management(netlmm) BOF was established at the 63rd IETF
(Paris) in August 2005. It discussed macro mobility
protocol without additional terminal functions andaccess-medium-independent fast handover withfewer negotiation messages.
The Detecting Network Attachment (DNA) WG istrying to improve the IPv6 address setup function,
which is a basic function of IPv6. This improvement
will provide much faster handover through decreased91

Global Standardization Activities

IPv6 address setup time.
IRTF (Internet Research Task Force), which isrelated to IETF, has some Research Groups (RGs).
The IP Mobility Optimization RG (mobopts RG) is
studying a method of providing link information notification between an MN and router at handover and amulticast handover method.
3. NTT activities concerning IP mobilitystandardization
We have being studying these IP mobility technologies since 1999. To enable us to use them in practice,
NTT is active in IETF standardization and in researchand development of Mobile IPv6 implementations.
Recently in IETF, we proposed the method of bootstrapping in the mip6 WG, the method of authentication between an access router and MN in the case of
fast handover in the mobopts RG, and the method ofroute optimization in the nemo WG. To achieve practical application of IP mobility technologies, we willcontinue to propose architectures and requirements
for these technologies from the viewpoint of telecommunication carriers.
References[1][2]

H. Ohnishi, Y. Takagi, and A. Kurokawa, “Mobile IP Technology,”
NTT Technical Review, Vol. 2, No. 7, pp. 61-66, 2004.
http://www.ietf.org/Toshihiko TamuraFirst Promotion Project and Emerging Communication Architecture Project, NTT Network
Service Systems Laboratories.
He received the B.E. degree in electrical engineering and the M.S. degree in material scienceengineering from Keio University, Yokohama in
1998 and 2000, respectively. In 2000, he joined
NTT Network Service Systems Laboratories,Tokyo. His research interests include ubiquitous
networks for realtime communication. He is also
engaged in the development of Mobile IPv6
agent and IPsec gateway systems. He is a member of the Institute of Electronics, Informationand Communication Engineers (IEICE) of Japan.

Hiroyuki Ohnishi
Emerging Communication Architecture Project, NTT Network Service Systems Laboratories.
He received the B.E. and M.E. degrees inmechanical engineering from Waseda University, Tokyo in 1996 and 1998, respectively. In1998, he joined NTT Network Service Systems
Laboratories, Tokyo. His research interests
include ubiquitous and mobile networks. He has
played an active role in IETF in developing anddisseminating mobile networking technology.
He received the Switching System ResearchAward from IEICE in 1999. He is a member ofIEICE.

Takeshi Ogawa
Senior Research Engineer, Emerging Communication Architecture Project, NTT Network Service Systems Laboratories.
He received the B.E. degree in applied physics
from Waseda University, Tokyo in 1989 and theM.S. degree in physics from the University ofTokyo, Tokyo in 1991. In 1991, he joined NTT
Network Service Systems Laboratories, Tokyo.
His research interests include ubiquitous andmobile networks. He has played an active role inIETF in developing and disseminating mobile
networking technology.

Yasushi Takagi
Director,First Promotion Project, NTT Network Service Systems Laboratories.
He received the B.E. and M.E. degrees inmechanical engineering and the D.E. degree in
information science and technology from Osaka
University, Osaka in 1985, 1987, and 2004,respectively. He joined the NTT Electrical Communication Laboratories in 1987 and engaged in
ATM network design and switching systemdevelopment. Since 1996, he has focused on thestrategic planning of next-generation broadband
network deployment. Currently, he works on thenext-generation Internet architecture and development of the IPv6-based service network. He isa member of IEICE.

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