Patent ID: 7911941
Filing Date: 2011-03-22
Classification: H04L

Abstract:
1. A router that is interposed between a subnet and a backbone network, the subnet includes a plurality of layer 2 switches and a plurality of terminals connected to the layer 2 switches, the terminals are communicating with each other via the layer 2 switches and a master router, wherein the router connects to the master router, the subnet and the backbone network, and originally operates as a backup router, but which can be transitioned to operate as a redundant master router, the router comprising: a severance detection unit which detects a severance between the layer 2 switches within the subnet; a redundant function control unit which, in the event that a severance within the subnet has been detected by the severance detection unit: a connection control unit which: an ARP transmission/reception unit, which in the event that a severance within the subnet has been detected by the severance detection unit: an ARP response forwarding unit which generates a learning packet for each ARP response packet, wherein the learning packet has the MAC address extracted from the ARP response packet, and forwards the learning packet to the terminal associated with the MAC address in the learning packet along the same routing from which the respective ARP response packet was received, except in the reverse direction.