Minimizing theNumberofConstraints forShared BackupPathProtection (SBPP)inShared Risk LinkGroup(SRLG)Optical MeshNetworks

Path-arc Integer Linear Programming (ILP) modelstheconstraint complexity ishigh. Path-arc approaches (1), (2), forSharedBackupPathProtection (SBPP)inoptical mesh (6), ontheother hand,arebasedonpathindicator variables networks generally contain manyredundant constraints for representing thetraffic volume carried onpathcandidates. The calculating sharedbackupcapacity. Thisgreatly increases the computational timeoftheILPsolvers. Inthis paper, we first s i t m identify thesharing relationship between working andbackup ca- quality (the minimization andthediversity) ofsets ofcandidate pacities, which facilitates thedevelopment oftwonovel algorithms routes. Current approaches topath-arc ILPmodelsforSBPP forminimizing thenumberofconstraints inILPmodels forSBPP arebasedonthegeneral formulation tocalculate sufficient inmeshnetworks. Next, weconsider themorerealistic caseof spare capacity foragiven traffic pattern. Thisleads toahigh SharedRiskLinkGroup(SRLG)networks, wheresomeopticalredcapcy forain taic pte n thispled oahi fibers havethesamerisk ofaphysical cutduetobeing bundledr o s inthesameconduit. Wepropose apath-arc ILPmodelforSBPP ILPsolvers. Inaddition, inrealistic WDM networks, many inSRLGnetworks andminimize thenumberofconstraints in fiber cables maybebundled inoneconduit toreduce the this ILPmodelusing theproposed algorithms. Simulation resultsconstruction cost. Suchnetworks arecalled Shared RiskLink showa remarkable reduction ofaround50%inthenumber Group (SRLG) Networks andasetofbundled fibers iscalled ofconstraints, whichsignificantly improves thecomputational Group (SRLG)N ondledsfibers iscaled