Patent ID: 7532620

Claim:
A routing table synchronization method that is used in a network apparatus including a forwarding unit corresponding to a base point for conducting packet transmission and reception with an external network, and a plurality of control units for operating a plurality of applications that are arranged to access virtual interfaces of the control units that correspond to actual interfaces of the forwarding unit so that the network apparatus appears from the outside to be functioning as a single unit, the routing table synchronization method comprising: executing a routing process of generating a routing table at a master control unit corresponding to one of the control units; updating a routing table of the forwarding unit by a routing synchronization process that operates independently from the routing process if the routing table of the master control unit is updated; updating one or more routing tables of one or more slave control units corresponding to the control units other than the master control unit through the forwarding unit; refraining from transmitting routing information pertaining to at least one of the virtual interfaces to at least one of the slave control units that implement said at least one of the virtual interfaces if said at least one of the virtual interfaces is down; transmitting a signal to at least one of the slave control units to delete routing information pertaining to at least one of the virtual interfaces from at least one of the routing tables of said at least one of the slave control units if it is determined that an operating state of said at least one of the virtual interfaces is switched from an up state to a down state; and transmitting routing information pertaining to at least one of the virtual interfaces to at least one of the slave control units that implement said at least one of the virtual interfaces if it is determined that an operation state of said at least one of the virtual interfaces is switched from a down state to an up state.