Patent ID: 6891840
Filing Date: 2005-05-10
Classification: H04L

Abstract:
1. A local area network path control system having a plurality of terminals and a plurality of hubs forming a simplex basic local area network, each of said terminals having first and second local area network controllers and assigned with specific internet protocol address, said first local area network controller directly connected to one of said hubs and assigned with first specific media access control address, said second local area network controller directly connected to another one of said hubs and assigned with second specific media access control address, either of said first local are a network controller or said second local area network controller put in service and serving as an active controller, said first specific media access control address used for an active media access control address when said first local area network controller is said active controller, said second specific media access control address used for said active media access control address when said second local area network controller is said active controller, wherein each of said terminals comprising: a first table for registering said specific internet protocol address, said first and said second specific media access control addresses and operation information indicating which said first and said second local area network controllers is put in service, a first broadcasting portion for broadcasting an address notification formed on the basis of registrations of said first table onto said simplex basic local area network when starting is carried out, said address notification including said specific internet protocol address as a source internet protocol address, and said active media access control address as a source media access control address, a replying portion for replying to another address notification transmitted through said simplex basic local area network, said replying portion transmitting a reply including said specific internet protocol address as said source internet protocol address and said active media access control addresses as said source media access control address to a source terminal of the other address notification through said simplex basic local area network, a second table for registering said source internet protocol address and said source media access control address included in each of the other address notification and another reply transmitted through said simplex basic local area network, a registering portion for abstracting said source internet protocol address and said source media access control address from each of the other address notification and the other reply to register them into said second table, a first failure detecting portion for detecting link failure between said active controller and the one of said hubs to which said active controller directly connected, a changing portion for changing said active controller between said fist local area network controller and said second local area network controller and for rewriting said operation information registered in said first table so that said operating controller indicated by said operation information is changed from one to the other of said first and said second local area network controllers when said first failure detecting portion detects said link failure, a second broadcasting portion for broadcasting a changing notification onto said simplex basic local area network when said changing portion changes said active controller, said changing notification including said specific internet protocol address as said source internet address and said active media access control address, and a rewriting portion for rewriting said second table about only said source media access control address in response to another changing notification transmitted through said simplex basic local area network.