Patent ID: 7327671

Claim:
A communication network comprising: a host network; a plurality of base stations; at least a mobile host capable of establishing links to said base stations; and a hierarchy-network of plural router-sets providing multiple-point routings between said base stations and said host network, wherein each of said router-sets further includes plural associated routers which provide the same communication route and which have the same routing informations, and a normally selected one of said associated routers in each router set is operational to provide said communication route, and if said normally selected one of said associated routers becomes inoperational, then another of said associated routers is selected to be operational to provide said communication route, thereby allowing continuous communication between said at least mobile host and said host network, wherein selection of one of said associated routers in each router set is made by a selected higher level router which manages said associated routers, and wherein the normally selected one of said associated routers in each router set sends said selected higher level router a message indicating that said normally selected one of said associated routers is operational, and if said selected higher level router has not received said message from said normally selected one of said associated routers in a predetermined time period, then said selected higher level router judges that said normally selected one of said associated routers has become inoperational, and said selected higher level router selects the another of said associated routers to provide the same communication route.