Cross-sharingvs.self-sharingtreesforprotecting multicastsessionsinmeshnetworks q NarendraK.Singhal a, * ,CanhuiOu b ,BiswanathMukherjee a a Department of Computer Science, University of California, Davis, CA, USA b SBC, 2600 Camino Ramon, San Ramon, CA, USA Availableonline1July2005 Abstract Inthisstudy,weinvestigateacost-effectiveapproachforprotectingseveralmulticastsessionsfromanylinkfailurein anopticalnetwork.Theapproach,referredtoascross-sharing,providesanoptimalsharingofbackupresourcesamong severalmulticastsessions.Ourcross-sharingapproachemploysthelink-vectormodel,modifiedformulticastsessions, andprovidessignificantcostsavings(48%forasmallsix-nodenetworkand39%foralargenationwidenetwork)of backupresourcesrelativetoarc-disjointandself-sharingapproaches,especiallyforalargenumberofsessions. Ó 2005 Elsevier B.V. All rights reserved. Keywords: Arc-disjoint; Cross-sharing; Idle-backup; Light-tree; Link-vector model; Multicasting; Protection; Wavelength-division multiplexing(WDM) 1. Introduction Recent advances in networking—particularly high-capacityopticalnetworkingemployingwave- length-divisionmultiplexing(WDM)technology— havemadebandwidth-intensivemulticastapplica- tionssuchasHDTV,interactivedistancelearning, liveauctions,distributedgames,moviebroadcasts fromstudios,etc.widelypopular [2–9]. However, linkfailuresinacommunicationnetworkoccurof- tenenoughtocauseservicedisruption,andleadto significantinformationlossintheabsenceofade- quate backup mechanisms. Hence, researchers have investigated efficient approaches such as arc-disjoint [10] and self-sharing [11] forprotecting multicasttrees,called‘‘light-trees’’ [3] inthelitera- ture.Becausesinglefiberfailuresarethepredomi- nantformoffailuresincommunicationnetworks, wefocusonprotectingmulticastsessionsfromany 1389-1286/$-seefrontmatter Ó 2005ElsevierB.V.Allrightsreserved. doi:10.1016/j.comnet.2005.05.024 q Ashort,summarizedversionofthispaperwillbepresented at the Optical Fiber Communications (OFC-05) conference in March2005 [1].Thisresearchhasbeensupportedinpartbythe NationalScienceFoundation(NSF)underGrantNo.ANI-02- 07864. * Correspondingauthor.Tel.:+15307525129;fax:+1530 7524767. E-mail address: singhaln@cs.ucdavis.edu (N.K.Singhal). ComputerNetworks50(2006)200–206 www.elsevier.com/locate/comnet