Redundantmulticastroutinginmultilayernetworkswithsharedrisk resource groups:Complexity,modelsandalgorithms

rge-scaledistributionofrealtimemulticastdata(e.g.,InternetTV,videocasting,onlinegames,stock quotes). Sincethesemulticastservicescommonlyoperateinmultilayernetworks,thecommunications paths needtoberobustagainstasinglerouterorlinkfailureaswellasmultiplesuchfailuresdueto sharedrisklinkgroups(SRLGs).Themainchallengeofthismulticastistoensuretheserviceavailability and reliabilityusingapathprotectionscheme,whichistofindaredundantpaththatisSRLG-disjoint (diverse)fromeachworkingpath.Theobjectiveofthisproblemis,therefore,tofindtworedundant multicasttrees,eachfromoneofthetworedundantsourcestoeverydestination,ataminimumtotal communicationcostwhereastwopathsfromthetwosourcestoeverydestinationareguaranteedtobe SRLG-diverse(i.e.,linksinthesameriskgrouparedisjoint).Inthispaper,wepresenttwonew mathematicalprogrammingmodels,edge-basedandpath-based,fortheredundantmulticastrouting problemwithSRLG-diverseconstraints.Becausethenumberofpathsinpath-basedmodelgrows exponentiallywiththenetworksize,itisimpossibletoenumerateallpossiblepathsinreallife networks.Wedevelopthreeapproaches(probabilistic,non-dominatedandnearlynon-dominated)to generatepotentiallygoodpathsthatmaybeincludedinthepath-basedmodel.Thisstudyismotivated by emergingapplicationsofinternet-protocolTVservice,andweevaluatetheproposedapproaches using reallifenetworktopologies.Ourempiricalresultssuggestthatbothmodelsperformverywell, and thenearlynon-dominatedpathapproachoutperformsallotherpathgenerationapproaches.