Inthispaper,theproblemoffault-tolerantroutingsinfault-tolerantnetworksisconsidered.Aroutinginanetworkassignstoeachorderedpairofnodesafixedpath.Allcommunicationamongnodesmustgoonthisrouting.Wheneitheranodeoralinkinafault-tolerantnetwork{ails,thecommunicationfromonenodetoanotherusingthisfaultyelementmustbesentviaoneormoreintermediatenodesalongasequenceofpathsdeterminedbythisrouting.Animportantandpracticalproblemishowtochoosearoutinginthenetworksuchthatintermediatenodestoensurecommunicationaresmallforanyfault-set,LetCdbeadirectedcycleoforderd.Inthispaper.Theauthor{irstdiscussesconnectivityofCartesianproductdigraphs,thenprovesthattheCartesianproductdigraphCd1×Cd2×…×Cdn(di≥2,1≤i≤n)hasaroutingsuchthatatmostoneintermediatenodeisneededtoensuretransmissionofmessagesamongallnon-faultynodessolongasthenumberoffaultsislessthann,ThisisageneralizationofDolevetal'sresultforthen-dimensionalcuhe.
