B-2 (Invited)

0ⅩC and ⅡIKARI router: Their use in IP over optical networks

Satoru OkamOto and Naoaki YamanakaNTT Network Imovation Laboratories, NTT Corporation

9-I I Midori-Cho 3-Chome Musashino一血i, Tokyo I 80-$585 Japan

Tel: +81 422 59 4353, Fax:十81 422 59 6387

E-mail: okamoto@exa.onlab.ntt.co.jp

Ab stract

AnOXC (optical cross-cormect)and a HIMrouter (photonic MPLS router) arc key components in

crea血g current and future IP-over-opticalnetworks･

This paper presentsthe current OXC and HM routertechnologies. Application examples of OXCs and

HIM routers arealso presented.

1. tAtrOdtlCtiotl

ne amotnt of rP data tra氏c has grown remarkably

over the past few years. Massive IP reuters and flexible

route甲ntrOl mechamims are required to help dcalwith

this grow血, and opticalteclmology must catch upwith

this tFend･ From the viewpoint of network control, MPLS

(multi-protocol label switching) ll】 has showngreat

promise as a solution to die grOW血h trafRc. MPLS was

imidated onthe corttrol plane of cell or hme basedsystems such as ATM (asynchronous transfer mode) and

ぬme relay･ A免w years ago, NTT proposedthe

Photonic MPLS conc甲t l2]. Ths concept includes

MP九S (multi-protocol la血bda switching) 【3] and

GMPLS - (generalized MPLS) 【4】, and has many

弓XtenSions血r photonic label switchhg tedmologies.

NTT demonstratcdthe HIM router bhotonic MPLSrouter) [5, 6] which is based on也e MP九S technologies

as the first realization of血e photonic MPLS concept･

the OXC is stzmgly associated widl the lP network

throughthe photonic MPLS concept and GMPLS. ThefW router evolves the OXC into an LSR (hb由

Switched router) which is categori2:ed as an IP router.the HM router provides mdti-layer　~tra瓜c

engneermg toolbox触ctions tothe IP-oveトOPtical

networks l7】. This paper presents the IPl0Ver-optical

netwo血　technologies, the OXC technologies,the

photonic MPLS concq)I, and HIEARI routerteclmologies.

2･ IP-over-opticalnetworkarchitecttlre

2.1. Ⅲl over VVI)M

Inthe early stage of the IP-over-opticalnetwork

development, an IP over WDM architccttm wasthe most

commonly used architecture. Underthe IP over WDM

architecture, POP古 (Point of Presences)are connected via

WDM transmission systcms･ Figure 1 shows　the

reference POP model of this networkarchitecture. The

POP is constructed with IP reuters and point-toIPOint

WDM transmission systems or fixed (i.e. not

recon点gurable) OADM (opticaladd/drop multiplexer)

Systens.

Inthis POP model, it is assumed that edge devices of

the optical network are WDM触mission systems. ne

OXC is not required because all the traLRcs isforwaFdcd

and routed in the IP layer. To re血ce　thc POP

construction cost, VSR (vety shorHlCaCh) hte血cs were

developed inthe OIF (opticalintemetworking forum) [8】.

The VSR interface was Brst utbed be触n IP reuters

that were installed on the same floor or in the same ofrlCe.

The血target of the coverage lengd1 0f the VSR

interfac苧is 300 trL The tltil血ion area of the VSR

interfacis is extended to betweenthe伊ro地r aJId the

WDM system, betwcenthe p router and OXC system,

and between the OXC system andthc WDM system.

TdFLtm local伊nctyvotb

Fig. 1 Reference POP model based on IP over WDM

architecture

2.2. htrodtICiJIg OXC into H'networks

ln the IP over WDM血shion, all the IP tra瓜C &om

neighboring POPE is routed tothe next hop Pops or localIP network at the IP reuters in the POP. Ifthe amount of

throughtrafnc is greater than that of the lo組l processed

traffic, a cut一也roughOr bypass in the Layer I network

becomes an attractive solution to reduce　the node

processmg cost. The OXC can be used to realiZetheLayer 1 cutthrough. This architecture is called the IPlover photonic network. The photonic cut-throughtechniquewill reduce the volume of 10 Gbps (STM-256

or OC-192C) forwarding by abotrE 1/3. Figure 2 shows

the results of a detailed study onthe cost effectiveness

achieved by usmgthe IP over photonic network

architecture. The calculation is based onthe estimated IP

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(Inv ited)

traffic demand for 2005 and state-of-the-art IP muters as

well as photonic teclmology･ The Cluster ratio isthe

cross trafrlC between routers, and so it does nat offer

effTective IPforwarding between users･ The Cluster ratio

is generally 2/3forthe current htemet in触structtue

traffic. According to the calcuhtion, We can expect a cost

reduction of more than 60% by using the photomic cut-

throughtechnique. Given die Current backbone networktrafnc pattern, we expect the photonic cut throughwillbe applicable more血an 60 to 70% of the time 【7, 9]･

Ano也er benefit to intmducing the OXC hto IP

networks is enhancement of die network protictiorL

mechanism. Ifthe OXC is iWed betweenthe IP routerand WDM syst田n, We Can install a shared restoration

mechanism or protection switching mechanism in the

opticallayer･

60

40

20

0

0%　　　20%　　　40%　　　60%　　　80%　　1 00%

ThrDugh hfh LlSing Layor 1 nehWks

Fig. 2 Cost re血ction effect using photonic cut

thFOughtechniqtl占.

3. 0ⅩC tecbologieS

3.1. Grooming fhctiotl (0⊥E9 0Ⅹq

In也e carlyぬge of the OXC system development, it

had been taken for gradedthat the OXC system would

use opticalSwitchhg点血rics･ This was chaDged when the

MONEY project 【101 incorporated electrical ,Switch

based cms840neCt Systems into the test-bed network

They de血ed血at the OXC has a叫arent switching

免mction･ Transparerlt switching means that hput digital

signals are Switched to the o叫trt podswithout changing

the signdformat and bitA}yte data･ Thisfundon is

naturally provided by the opticalSwitch based cross-

comect systems･ me elcctricalSwitch based OXCsystem does nbt provide the signalfomat restriction丘ee

feattwe. Basically, Only the SDH/SONET signalcaJl be

switched. Th耶fore, COmerCial OXC products have a

/儲

EE=iLiiCi SjNE

Fig, 3 0-E,-0 0XC application example

(grooming box).

SDH/SONET multiplexingfunctionwithinthe OXC box･

All incommg SDH/SONET signals, such as 52 Mbps,

156lMbps, 2.5 Gbps, 10 Gbps,and 40 Gbps inthe near

future, are demultiplexed into 50 Mbps PC3/STS-1level) signals. They are switched and multiplexedinto

high-geed outgoing SDH/SONET signals such as 2･5Gbps, 10 Gbps, and 40 Gbps, andvice versa･ This

function is called a grooming Rmction･ As show in Fig･

3,the electriCalswitch based OXC is constructed using◆ヽ

the conventional SDH/SONET digital　cross-connect

system and ･SDH/SONET MUX (multiplexer)･ 取is type

of OXC system is called an OIE-0 type OXC･

3.2. JtlnCtiotL BOX ftITICtiotI (0-0-0 0ⅩC or PXq

In 1999, MEMS (micromachine electro mechamiCalsystem) technologies became fcaSlble･ The optical

MEWS switch, especiauy the　3D-MEMS switch,

慧霊等意S13:器hPObdsc.exdFssiodne慧慧denoted as 0.0-0 typ_e OXC or PXC bhotonic tFOSS-

co品ect). Basically PXC systems provide a 8ignalforrrnt

restriction Bec feattFe. Therefbre,the MEMS based

large-scale PXC provides dle Central丘ber management

system血nction atthe POP･ At each floor, a medium

scale PXC system is used as a JtnCtion box or a patch

panel･Anapplication example of the PXC野Stem is

shown in Fig･4･ ne remote　丘bcr con点gtmtion

management capabilitywill reduce the operation cost of

netwo血operators.

0ⅩC - ConLigtmble jⅦ血ozl bcEXL

LI

PXC: Photonic cm㌻conncc(

Fig. 4 PXC application example Ounction box)I

3.3. Ctlt throtLgh　fbnction otltSide WDM systems

(AON-XqThe OXC and P玉C mentioned in Section 3.1 and 3.2

required long-haul transtnission systems for inter o用･ce

trafRc transmission. The cross-cormect system provides

the trairlC grOOming血nction and the丘ber con丘guration

Rmction between IP routers and WDM systems. Tie cut

也rough触ction merltioned in Section 2･2 Canreducethe

switching cost･Asa result, transponders located inWDM systems dominate over the end-to-end

transmission.cost. This problem can be solved with all-

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B-2 (Invited)

Optical cutthrough　teclmiques, Figure　5　shows an

example of the all-opticalcutthrough. Inmis example,IP routers aS Well as WDM systems are cut throughbyPXCwithWDM input/output ports･ There is no OfE and

E/0 conversion point along the cut throughopticalpath.As the ultimate opticalnetwork, an AON (al110Ptical

network) which does not containany O侶and E/0

devices within a core network node was studied. The

transparent bit-rate-restriction･aee network is very

attractive血)mthe vleWPOints of low costand high

flexibility･AnAON-XC is defined as a PXC system withWDM input/output ports. To enhancethe network size

scalability of AON, insertion of 2R or 3R (reshaping,

retiming, (and regeneration)) devicesinto an AON-XC

system is required･ ⅥleSe devices are inserted adaptively･

In other words, if the signal is degraded by fiber loss as

well as nonlinear effects such as PMD (po如ization

mode dispersion) or ASE (amplified spontaneous

emission),the 2R or 3Rfunction is activated. NTT

developedan0ⅩC prototype system that emuhtes the

AON･ⅩC tll, 12】.

The integration of WDM and PXCaids in reducing

opemtional　80StS, maintenance costs, device costs,

ofnce-space requuements, electrical energy, and the rate

of failure･ Inthe next generation, AONswill beextremely important andthese aforementioned features

will provide great beneRts.

OXC-WDM integrated opticalSwitch

Fig･ 5Al1-Optical cut througharchitecture: POPwithAON-XC_

4･ HIKAm router techJ101ogies

4･1･ Concept of photonic MPLS

MPLS stands for uMulti-protocoln Label Switching.

The multi-protocol means　that its techniques are

applicable to anyand multiple network layer protocols･

The initialMPLS was likened to a `shim-layer'which is

used to provide connection services to IP and which

itself makes use of bkllayer services &om Layer 2. IP

packets are accorr-Odated into a label switched path

G.SP) which is distinguished and switched by a labelvalue inthe shin-header. To set upthe LSPwithinMPLS networks, several signaling protocols such as

LDP (label distribution protocol), CR-LDP (constraint

based routing LDP),and RSVP-TE (resource reservation

protocol tra瓜c engineering) are now being developed.

These slgnaling protocols are used to set up switching

devices to definethe route of LSPs. Therefore, these

protocols can be applied to any label switching devicewhich is not only based on packet, cell, or舟ame

switching butalso based on circuit switching, This is the

concqd of GMPLS l4]. In awide sense, a photonic

MPLS belongs tothe category of GMPLS. The photonic

MPLS concept covers all photonic label switchingL

technologies. Examples of photonic labels are (a)

physical labels, such as wavelength(S), waveband, andmode (or phase) of lightwaves, 0)) optic?I data labelswhich are multiplexed by OCDM (opticalcode division

multiplexing) technologies or optical SCM (sub-carrier

multiplexing) technologies, and (C) time slot labels, in

the case of OTDM (optical time division multiplexing)

transmission. These labelsare added to GbE (gigabit

E血emet) streams, 1 0GbE streams, SDH/SONET strews,

optical channel (OCh) [13] streams, optical bursts which

are de血ed as a short hold stream, and opticalpackets

which are叫orted in a store and forward manner. ､

4.2. m rotLter (phototLic MPLS rotLter)To realizethc photonic MPLS conc甲t, aS a丘rst step,

m developed MP九S based photonic MPLS reuters l5,

6]. Ths photonic MPLS router is named "HIKARI

router" [7】. The HIEARI router i.s an integrated system

with IP/MPLS routersand opticalswit血based OXCs

伊ⅩCs). The HIM router hasanIP routing capability,

PSC (packet switching capability), and LSC (lambda

switching capability). This isthe major difference from

conventionalPTSsかhotonic transport systems) such aS

0ⅩCsand OADMs l12]. Tie HIKARI router not only

works as an intelligent OXC and an LSR but also γorks

as a multillayer tra】限c engineering toolbox t14】.

Therefore,the HM router operates inthe IP layer,LSP layer,and OLSP (Optical LSP) layer. LSPs are

seamie5Sly connected by OLSPs,and LSPs areaggregated on OLSPs. nerefore, a controller canmanage OLSPs as a layer inthe LSP hierarchy.

Figure 6 shows afunctional configuration of the

HKARI router. The HIM router compnses fivefunctionalblocks: a WDMfunctionunit,anoptical

Switch unit, an Ll (Layer 1)-trunk unit, an L2凡3 (Layer

2fLayer 3) trunkunit, and a NE-manager (network

element manager).AnLRU (lambda routingmit) isdefmed as an integrated umit &om the WDM unit,the

opticalSwitch unit,andthe Ll-Tnlnkunit･ The LRU can

switchand add/drop OLSPs, and wavelengthconversion

is performed atthe九一conv (wavelcngthconverter) in Ll-

trunks. The NE･manager momitors all　the circuit

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B12 (Invited)

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P �� � �� ��

告等 �� � � �� ��

讃指 �� ��鮭 嘉 � �%r� �� ��

善男 S � ��Y?D｢譌)?�� ��

LRU-WDLA+Optl榊)剖〝　LRU : LJmbda Rodlq Ud

･Ll ･Trwk a= :Fnd叩Eqb

l.¢onv : LAFr)bdJ COrrVN

NE : N仙Eb巾●d

Fig. 6 HM router血nction configuration.

elements inthe node, supervises remote optical repeaters,

performs res/toration} monitorsthe quality levels of thesignals (Ll level and L2 level), and controlsthe LSPs

and OLSPs.

4.3. IP backbozLe netWOrks coIlStnLCtedwith EI7mro uters

Figure 7 shows an application example of the HIMrouters, The photonic MpLS network is de血ed as a core

network in　the MPLS based IP backbone network.

Customer IP routers and MPLS routersare corLneCted to

the MPLS based backbone network.AnNMS (networkmanagement system) of the IP backbone network

manages a hitrarchicalLSP network. Because LSPs and

OLSPs can be managed by ahnostthe same management

entity, this Rmction can enhancethe scalability of the

backbone network. Because each hierarchy generates

management sections, in a two hierarchy case, i.e., one

LSP and one OLSP,the backbone networks are divided

into MPLS router network sectionsand HM routernetwork sections. This hierarchy can be extended to

several LSP hierarchies and severaLOLSP hierarchies.

The photomic MPLS technologies havcthe potential to

Cuさbm的　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　CtlぬmBrS

RBUtBrB RouterB

Fig. 7 Application exampld ofHIEARI router

network.

enhance the node witching capacity h order to reduce

the power consumption and the equipment space.

5. Conchsion∫

Current OXC teclmologies and ･HIKARl router

technologies for creating the IP-over叫Ptical networks

were presented･ We must enhance the intelligence of

OXC systems to utilizethem effectively as a kind of

pseudo IP router system.Asan intelligent system, IProuter systems, which were免rst conceptually designedin

March 1973, have continuously evolved over 30 years.

On the other hand, development of intelligent OXC

systems has started only withinthe past fTew years.

Therefore, we must cultivate and improvethe sense of

the intelligent OXC systems and HIKARl router systems.

Referemc eTs

l1] IETF RFC3031 "MultiprotocoI Label SwitchingArchitecture", 200 1.

[2] OIF2000.017 "A proposal of the Photonic MPLSNetwork", 2000.

[3] dra允-awduche-mpls-te-optical-03.txt,　work　in

progress, lntemet draRinww.ietf.org, 200 1.

[4] dra允-ietf-ccamp-gmpls-architecture-03.tnt, workin

progress, Irtternet dra允 in ww.ietf.org, 2002.

[5] K. Shimano, Atsushi hnoka, Yoshihiro Takigawa,and Ken-ichi Sato, "MPLambdaS demonstration

employing photonic routers (256Ⅹ256 0LSPs) to

integrate opticaland IP networks'', NfOEC2001,

proceeding vol. 1 pp. 5-13, 2001.

【6l F. Kano, T. Kawai, Y. Takigawa,and K. Sato,"Development of PhotomiC Router (256X256

0LSPs) to Realize Next Generation Networkwith

MPLambdaS Control", NFOEC2001, Proceeding

vol. 1 pp. 458-464, 2001.

m K. Sate, N. Yamanaka, Y. Takigawa, M. Koga, S.Okamoto, K･ Shiomoto, E. Oki, and W. Imajukn,"GMPLSIBased Photonic Multilayer Router

(Hikari　Router) Architecture:An　Overview of

TrafrlC Engineenng and Signaling Technology,''-

IEEE Comnications Magazine, pp. 96-101,March 2002.

[8] http://m.oifTorum.com/【9] A. Watanabe, S. Okamoto, and K. Sato, `WDM

optical path-based robust IP backbone network/'

OFC'99 proceeding, TuF1-3, March 1 999.

[ 1 0] http://www.bell-labs.com/projectMONET/mon_pro. html

llll M_ Koga, A. Watanabe, S. Okamoto, K. Sato, H.Takahashi,and M. Okuno, "Opticalpathcross-Cornect demonstrator designed to achieve　320

Gbit/S,''Proc. ECOCt96, The.3.1, Sept. 1996.

【12] S. Okamoto, M. Koga, H. Suzuki, and K. Kawai,"Robust photonic transport network implementation

with optical　cross-connect systerru,'' IEEE

Communications Magazine Vol. 38, No. 3, pp. 94-103, Mar血2000.

【13日TU-T G,709, `Wetwork node interfaces for optical

transport network (OTN)," 200 I.

[14] E･ Oki, K. Shiomoto, S. Okamoto, W. Imajuku, andN. Yan辺naka, "A Heuristic Multi-Layer Optimum

Topology Design Scheme Based on Trafnc

Measurement fわr IP+Photonic Networks," Proc.

OFC2002, TuP5,Anaheim USA, March 2002.

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