WAVELENGTH SELECTIVE WDM NETWORK DESIGN- HOW BAD IS

WAVELENGTH SELECTIVE WDM NETWORK DESIGN- HOW BAD IS -...

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Unformatted text preview: 2007IEEEInternationalConferenceonSignalProcessingandCommunications(ICSPC2007),24-27November2007,Dubai,UnitedArabEmirates WAVELENGTH SELECTIVE W D M NETWORK DESIGN: HOW BAD IS SHORTEST PATH ROUTING? MohamedSaad Dept. ofElectrical& ComputerEngineering UniversityofSharjah,UAE ABSTRACT Givenacollectionoflightpathrequests,we considerthe problemofallocatingfiberstothelinksofaWDM net- workatminimumcost,suchthatalllightpathrequestscan besimultaneouslyrealized. Itisknownthat,undermod- ularfibercapacityassumptions,shortestpathroutingmay notminimizethetotalfibercost. Inthispaper, we ex- tendourpreviouswork forwavelengthconvertiblenet- works [8,9],andtheoreticallyquantifytheincreasein fibercostduetoshortestpathroutinginnetworkswithout wavelengthconverters. Inparticular,weprovethatshort- estpathroutingisasymptoticallycost-optimalinheavily loadednetworks,andasymptoticallynear-optimalinlarge, sparsenetworksthatsupportall-to-allcommunication. Index Terms- WDM networks, capacityplanning, shortestpath,approximationalgorithms. 1. INTRODUCTION Opticalnetworksthatemploywavelengthdivisionmulti- plexing(WDM) arepromisingcandidatesforprovidinga flexiblebackbonenetwork. Inparticular,WDM divides thefiber'shugebandwidth(nearly50Terabits/s)intomul- tiplewavelengthchannelswithbandwidths(10Gigabits/s or40Gigabits/s)compatiblewiththeenduser'selectronic speed. ThebasicserviceofferedinWDM networksisa lightpath, an all-opticalcommunicationchannelbetween two nodesthatbypasseselectronicpacketprocessingat intermediatenodes. Thesetofestablishedlightpathscan beviewedbyhigher-layerprotocolsasavirtualtopology residingontopoftheunderlyingphysicaltopology. Thispaperconsidersafundamentaljointphysicaland virtualtopologydesignproblem,whichwesimplyreferto asWDM networkdesign.Givenasetoflightpathrequests, we seektoallocatezeroormore fibersonthelinksofa WDM networkatminimum cost, suchthatalllightpath requestscanbesimultaneouslyrealized. Oneoftheearlieststudiesonallocatingcapacityonthe linksofaWDM networksuchthatasetofconnectionre- questscanbesimultaneouslyrouted,wasreportedin[2]. Otherstudieswere reportedin[1],[10], [11]and [13]. Somestudies,e.g.,[1],[3],and[5]focusedonaddingsur- Zhi-QuanLuo Dept. ofElectrical& ComputerEngineering UniversityofMinnesota,USA vivabilityconstraintstotheWDM networkdesignprob- lem. Forsimplicity,we assumethateveryconnectionre- questisrealizedbyaworkinglightpathonly,i.e.,we do notconsidersparecapacityallocation.Similarlyto[8]and [9],however,theformulationsandtechniquespresentedin thispaper,canbeeasilyextendedtocaptureedge-disjoint pathprotectedconnectionrequests. TheWDM network designproblemwas mostlyformulatedasanintegerlin- earprogramthatisNP-hardtosolve. Exactsolutionap- proacheswithexponentialcomplexity,e.g.,branch-and- bound[11],orheuristics[1,2,3,10,13]havebeenpro- posed....
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WAVELENGTH SELECTIVE WDM NETWORK DESIGN- HOW BAD IS -...

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