Patent ID: 7817637

Claim:
A network switching system configured by connecting a plurality of network switching devices, the network switching system operating virtually as a single network switching device wherein each switching device of the plurality of network switching devices comprises: an address range storage that stores a handling address range pre-assigned as a range of network layer address, said each switching device being responsible to associate between the network layer address within the handling address range and a target transport destination device; a data receiving unit that receives lower transport layer data including: a destination network layer address which represents a network layer address specifying a destination in the network layer; and a destination lower transport layer identifier which is a lower transport layer identifier specifying a destination in a lower transport layer below the network layer; an assigned data transport unit that, if received data received by the data receiving unit is the lower transport layer data including the destination lower transport layer identifier specifying said each switching device and if the destination network layer address is an assigned address assigned to said each switching device, generates lower transport layer data including a corresponding identifier as the lower transport layer identifier of the target transport destination device corresponding to the destination network layer address, and transports the generated lower transport layer data on the basis of the corresponding identifier; an unassigned data transport unit that, if the received data includes the destination lower transport layer identifier specifying said each switching device and if the destination network layer address is an unassigned address not assigned to said each switching device, transports the lower transport layer data to another switching device among the plurality of network switching devices to which the unassigned address is assigned, while setting the lower transport layer identifier of the another switching device to the destination lower transport layer identifier; and a lower transport layer transport unit that, if the received data includes the destination lower transport layer identifier specifying a device different from said each switching device, transports the received data on the basis of the destination lower transport layer identifier.