R&D Spirits
Ahead of the World’s Telecom Carriers in
Developing a Photonic Network for IP
Yoshihiro Takigawa
Group Leader
Photonic Networking Research Group
Photonic Transport Network Laboratory
NTT Network Innovation Laboratories

In response to the rapid increase in IP traffic volumes, research into photonic networks that
dramatically improve the quality and economy of networking has become an arena for fierce
competition among the world’s large telecom carriers. At NTT, the Photonic Networking
Research Group of the Network Innovation Laboratories has played the leading research role inthe development of Photonic Multi-Protocol Label Switching (MPLS) routers. The Group’s
research in this area is now moving toward its final stage. We spoke to Group Leader Yoshihiro Takigawa to clarify the present situation as his group’s research heads for commercial application at the end of fiscal 2005 and to talk about the future.

Research Focus Shifts to Experiments with
Prototypes. Goal is Practical Business
Application from the End of Fiscal 2005
Editor: What are some of your group’s current
research themes?
Takigawa: Our Group’s main research is in the areaof photonic networks. Typical products that we are
studying are Photonic Multi-Protocol Label Switching (MPLS) routers and optical cross-connect nodes.
Our research includes the development of technology
for various key system elements, technology forcomponents, network design, and operation andmaintenance tools. We are not doing all the development work ourselves, of course, but are collaboratingwith other organizations in NTT, such as the NTT
Photonics Laboratories, the NTT Network Service
Systems Laboratories, and software developers outside the NTT Group. Our Group, however, is charged
with pulling together the overall research and preparing the final system for a new business opportunity.
E: In what areas will the results of your group’s
research be applied?
4T: The technology will serve as the core for NTT’s
next-generation network, the Resonant Communication Network Architecture (RENA). As broadband
usage and related services expand on the Internet in
the future, tremendous volumes of information willflow through networks. It is clear that the present system that involves optical-electrical-optical conversion will soon reach the limits of its capabilities. If
information is routed solely through optical technology, the burden on the overall system will be greatly
reduced (Fig.1). Based on that thinking, we developed a Photonic MPLS router—the HIKARI
router—that uses wavelength as the identifier fortransferring IP packets (Fig.2).
E: What are the main technical points of your group’sresearch?
T: One of our main research areas is network restoration by providing minimum redundant capacity for
failure recovery of Internet links and nodes. For
example, if three locations A, B, and C are each connected by 10 Gbit/s lines, the simplest and safest
backup would be to reserve identical capacity foreach link. But doing so would mean adding two 10NTT Technical Review

R&D Spirits

WDM controlled by electrical IP router
Traffic jam at node
WDM links

IP packet

IP routerPhotonic MPLS
Wavelength path

WDM link

Existing network

IP routerPhotonic network
Wavelength routing

PTS
PTS: Photonic Transport SystemFig. 1. Wavelength routing on photonic superhighway.

NE-MgrMPLS router unit
NE-Mgr

NE-MgrLambdarouting unit

HIKARI
router

HIKARI
router

PAD unit
WDMunit

Opticalswitching unit

WDM
unit

Composition of Lambda routing unit

NE-Mgr: Network Element Manager
PAD: Payload Assembler/Disassembler

Fig. 2. Functional Components of HIKARI Router.

Gbit/s lines (e.g. a total of 20 Gbit/s) for each link, acompletely uneconomical approach. Using the network restoration technology, a single reserve link of
10 Gbit/s could be designed to back up all three locations, with emphasis on dependability and economy.
Vol. 1 No. 5 Aug. 2003

Another area of interest for us is a signaling method
called Generalized MPLS (GMPLS). When a network becomes extremely complicated the management of nodes surpasses human capabilities. GMPLS
allows information to be automatically provided5R&D Spirits

between nodes on a network whitch are installed,reconfigured and removed. Even without centralized
management it can make such an arrangement on thenetwork smoothly and efficiently.
E: With such technology, what can we expect to happen in three to five years from now?
T: Usable bandwidth will expand by a full order ofmagnitude, making it possible to read magazines andnewspapers on the Internet, and to relax and watch
movies and videos without interruption. And as theInternet becomes more economical, there will be atremendous increase in the number of Internet users.
Once we reach that point, some aspects of society
will change. At any rate, our group is moving towardthat kind of future, and we plan to introduce our firstsystem with RENA when that service is introduced at
the end of fiscal 2005. Service will be provided initially in large cities like Tokyo and Osaka, and will be
expanded gradually afterward to eventually cover allof Japan.
E: What is the current status of your group’s
research?
T: Prototypes of the HIKARI router have alreadybeen built, and we are now conducting experiments.
We have to verify the equipment with various kindsof checks, including not only fast restoration technology but also size and cost of the equipment. We arealso studying ways to guarantee quality and economy
for media streaming of large-volume media such asmovies and newspapers.

Balance between Competition andCooperation, and Developing an R&D
Strategy
E: What are the main domestic and overseas trends inyour group’s area of research?
T: The research we are conducting is currently one of
the hottest research areas worldwide. The major vendors and telecom carriers around the world are competing in the area of GMPLS research, and moves areprogressing toward standardization. Concerning theHIKARI router, meanwhile, there are still almost noorganizations using it, mainly because the performance and functions already achieved are not yet felt
needed. In a few years, however, it is absolutely certain that other organizations will introduce similar
6equipment. So we must not be satisfied with what wehave accomplished. Actually, until a few years ago
something like 10 or 20 U.S. companies—from large
corporations to venture businesses—competed
intensely in the area of optical crossconnectors. Afterthe IT bubble burst, however, almost all of them halted their work. Essentially, the only other company
now conducting research in the same area as us isCalient Networks.
Telecom carriers are the main participants conducting research in the area of restoration, and the competition is intense. Among them, the two mostadvanced organizations, as viewed from the level ofpapers being presented at conferences and forums,
are NTT and France Telecom. NTT has conducted
experiments with fully supported prototypes that permit switching among three nodes within 700 milliseconds. France Telecom’s product can switch
among four nodes in one second or less. Although
there are differences in the experimental conditions,the products of both companies perform at about thesame level. Despite not having presented papers atconferences, Deutsche Telekom has probably alsoreached the same level of research as NTT and FranceTelecom.
In the U.S., the government has taken the lead inpromoting research in this area, keeping it an “allAmerican” undertaking. It appears that R&D is being
powerfully promoted across a wide spectrum ofactivities in the U.S. Against that backdrop it would
seem that worldwide competition will become evenstiffer in the future.
E: Given the difficult competitive situation, is yourgroup cooperating with any organizations overseas?
T: Although research in the area of restoration ismutually and totally competitive, both competitionand cooperation exist in research in the area ofGMPLS. That is quite natural, because the Internet isa connection of networks around the world. The different carriers must be tied together. Also, technological progress in GMPLS is very fast. If research wereto be conducted in isolation, a company would not beable to respond to the speed of the advances beingmade. From the viewpoint of research costs as well,give-and-take relationships have inevitably developed among the major players. Basically, however, itremains a competitive environment, making it difficult to maintain a balance between what to reveal andwhat to keep hidden. A good sense is needed for thatkind of decision. Although companies earn a sort ofNTT Technical Review

R&D Spirits

batting percentage for how they handle that balance,
fortunately nobody knows about most researchbecause it is conducted behind closed doors—which,of course, is true for both sides. Our group feels it
would be interesting if we could develop technologythat influenced networking and guided it in a certain
direction. We enjoy attempting different researchtasks with that in mind.

Introducing NTT Technology to the Worldthrough International Activities
E: Please outline the sort of joint research your groupis conducting with overseas organizations.
T: Our group is collaborating with two overseas organizations. One is the Electronic Visualization Laboratory (EVL) of University of Illinois Chicago. EVL
focuses pretty much on the development of virtual
reality devices. To provide EVL with services in thefuture, we are working with them to study their product quality requirements and network configurations.
We are also providing them with system proposals.
The second overseas organization is the Information
Society Technologies (IST) Programme, an EU program. Our group worked with IST from 2000 toMarch 2003 by participating in the Layer Interworking in Optical Network (LION) project for conducting experiments with mutual connectivity of opticaldevices. The second project, the Next-generation
Optical network for Broadband in Europe (NOBEL),
is scheduled to begin this fall. IST has asked NTT toparticipate in this new project as well, and we probably will do so.
E: What activities does your group conduct withinternational forums and committees?
T: Concerning activities related to standardization,
we took the initiative when we participated in activities of the ITU-T and the Internet Engineering Task
Force (IETF) and Optical Internetworking Forum(OIF) in the U.S. Normally we would also participate
in the vendor-related MPLS Forum, but in considering the benefits to us versus the time and funds
required we decided not to participate. Based on ourstrengths as a telecom carrier, our standardization
strategy is, first, to approach ITU-T, and then toapproach OIF and IETF more forcefully.
E: What reaction has there been thus far to yourgroup’s research results and other activities?
Vol. 1 No. 5 Aug. 2003

T: In 2001 we prepared a dynamic presentation of theHIKARI router for display at the SUPERCOMM thatyear in the U.S. Many companies expressed a strong
interest in the router at the show, even asking about
when the product would be marketed. That display, I
am convinced, told the world that NTT is much morethan merely a telecom carrier. We heard the same
response when we participated in the LION project.
Also, at last September’s World Telecommunications
Congress – International Switching Symposium(WTC-ISS), held in France, we conducted open
experiments of our optical restoration system. By
coincidence, France Telecom showed a similar system at the same symposium. It seemed clear to me atthat time that France Telecom was surprised at NTT’spresentation. Some of those attending the symposium
asked us straight out how the results of our experiments would compare with France Telecom’s system
if we operated our system under the same conditions
as theirs.
E: Tell us about the sort of tasks your group faces in
the future.
T: Our most important technical task is to shorten theunavailable time of restoration. The ultimate objective in restoration research is to provide the same performance as if there were exclusive backups for eachlink. It is no exaggeration to say that accomplishingthat task would contribute to NTT being recognized
as a worldwide telecom carrier conducting successful
research in networking. Another major task facing
our group, as a research lab in a private corporation,is to make our overall system economical. At thesame time, I would like to see us move forward withselling to the outside, through companies in the NTTGroup, some of the products and functions we eventually develop. Having technology that we can market will allow us to contribute to the overall revenuesof the NTT Group. We would also like, of course, tooffer unique services of our own. Those are roughly
the major tasks we face for the future.

Making the Most of Widespread ResearchExperience to Pursue Best Technology
E: What major fields of research have you been
involved in up to now?
T: My major research at Waseda University was wireless power transmission using microwaves and millimeter wave bands. In one research task the objective
7

R&D Spirits

was to equip a satellite with solar cells, generate electricity—which is done efficiently in space—andtransmit power back to earth. The two main problems
were how to convert electric power into microwaves,and how to accurately control their direction of thepropagation.
After joining NTT in 1982, I spent ten years in
R&D related to ISDN subscriber systems, from thestart of the research project, through the start of service, and afterward on making the system more economical. The system I worked on was introduced to4,000 telephone offices nationwide. After that, myresearch shifted to Passive Optical Networks (PON)
for ATM. In that research as well I was involved fromthe start of the project and stayed with it until justprior to service commencement. The period happened to coincide with the NTT’s multimedia trials,and I participated in experiments conducted in Yokosuka and Urayasu on a new image distribution service. After that, I moved over to NTT Communications and was involved in promoting ATM multimedia services through the Asia Multimedia Forum(AMF). Three years ago I returned to NTT in the Photonic Transport Network Laboratory and since thenhave been involved in the research I am doing now.
The targets of my research, including my university
studies, have changed greatly over the years. The
wide gamut of research being conducted at NTT was
one of the attractions for me when I joined the company, and I consider myself fortunate for always having been involved in research I enjoy.
E: Why do you think NTT selected you to head theGroup?
T: There were probably several reasons for considering me as the most appropriate person to head theGroup. Because of my varied experience, for example, it was obvious that I understand the basic
research process. Also, I have overseas experience inpromoting NTT’s products and services, and havebeen involved in high-level discussions with nonresearchers in government. When I was involved in
the ATM-PON research project, moreover, I submitted as many as 25 different papers to the ATM Forumas part of my activities related to international standardization. At the time, that was a tremendous number of papers for a Japanese researcher to submit tothe ATM Forum. Perhaps that was one more reason
for my selection.
E: Based on your experience to date, how do you
8think the rest of the world views NTT?
T: NTT proposed a number of technologies in thearea of network infrastructure that later became international standards. So among telecom carriers NTT isrecognized as having sophisticated technology usable
anywhere in the world. When it comes to the Internet,
however, NTT’s name, unfortunately, is not wellknown yet. When router vendors come together atforums and other conferences and hear the nameNTT, they sometimes ask if NTT is a subsidiary ofNorthern Telecom (laughs). Even in this area, though,NTT has outstanding technologies. That’s another ofour future tasks: to make the NTT name more familiar in the Internet field.
E: Please share with us some of your thoughts about
the future.
T: It would be nice three to five years from now if
NTT could be providing networking services, collaborating with other companies and organizations along
the way, and producing the best possible technology
to represent the overall NTT Group. Personally,meanwhile, I would like to work with experimental
studies of the basic constituent technology. I havedone much research up to now related to systems. I
was left pretty much to myself, and achieved a certain
level of accomplishment. But there was little opportunity during that time to write papers related to formulas and experiments, i.e., the basic constituent
technology. Doing so would give me additional experience and allow me to broaden myself as a
researcher. If the company allowed it, that is something I would like to do.
E: What has the NTT Laboratories meant to you personally?
T: The NTT Laboratories has not only let me confirm
my technical competence, my overall capabilities,
and my opinions and views at an international levelbut has also allowed me to improve myself further.
One of the old-timers at NTT once said to me many
years ago that NTT’s laboratories were kinds of training places for researchers. Today I understand what
he meant, and I agree with him. In the NTT research
environment I was allowed to do work that I enjoyed
and that had meaning for me. Today, many young
people are choosing to work in situations not directly
related to technology or R&D. There is nothing
wrong with that, of course, but if matters continue as
NTT Technical Review

R&D Spirits

it is, Japan will have no technology of its own in thefuture. To prevent that from happening, we must getyoung people, including university students, tounderstand and appreciate the attractive qualities oftechnically oriented corporate groups such as NTT.
That can probably be listed as another of our Group’s
roles in the future.

Vol. 1 No. 5 Aug. 2003

Interviewee profile■ Career highlights
1980 Graduated from Electronic Communications
Department, Faculty of Engineering, Waseda
University, with B.A.
1982 After graduating from Graduate School ofWaseda University with M.S., entered Nippon
Telegraph and Telephone Public Corporation(now NTT).
2000 Photonic Transport Network Laboratory of
NTT Network Innovation Laboratories■ Major awards
1989 NTT President’s Award
1996 NTT President’s Award
1998 NTT President’s Award■ Professional associations
Member of the Institute of Electronics, Information
and Communication Engineers

9