Inter-local area network connecting system

Claim 2

An inter-local area network (LAN) connecting system in which LANs are connected to an asynchronous transfer mode (ATM) switching network by respective bridge devices to effect communication between terminals connected to different LANs through said bridge devices and said switching network, comprising: logical connections set between said bridge devices in advance to transfer cells, which are information units of data transfer; and each of said bridge devices having means for dividing an information frame received from a terminal connected to a LAN accommodated in this bridge device into a plurality of cells and sending out said cells to said ATM switching network, means for restoring an information frame from a plurality of cells received from said ATM switching network and sending out said restored information frame to the LAN accommodated in this bridge device, a first address table on which the addresses of terminals connected to the LAN accommodated in this bridge device are registered and held by learning, a second address table on which the addresses of terminals connected to LANs accommodated in other bridge devices are registered and held by learning in pairs with identifiers that identify logical connections between this bridge device and the other bridge devices, and means for checking address information of an information frame received from a terminal connected to the LAN accommodated in this bridge device or address information of an information frame restored from a plurality of cells received from said ATM switching network against said first or second address table, to judge the destination in accordance with the registration condition of said first or second address table, and effecting communication on the basis of the result of the judgement.

Claim 3

An inter-LAN connecting system according to Claim 1, wherein said information frame has a destination address and an originating address, while the identifier of each cell is a virtual channel identifier (VCI), and said communication means further has means for checking whether or not the originating address of said information frame received from said LAN has been registered on said first address table and registering, if it has not, said originating address on said first address table, and further checking whether or not the destination address and originating address of said restored information frame have been registered on said second address table and registering, if both said addresses have not been registered, said originating address and said VCI on said second address table, thereby realizing registration and holding of information on said first and second address tables by learning.

Claim 4

An inter-LAN connecting system according to Claim 2, wherein said communication means further has means for checking whether or not the destination address of said information frame received from said LAN has been registered on said first and second address tables, abandoning said information frame if said destination address has been registered on said first address table, transmitting, if said destination address has not been registered on said first address table but it has been registered on said second address table, said information frame to the bridge device designated by the VCI registered on said second address table, and broadcasting said information frame to all the other bridge devices if said destination address has not been registered on either of said first and second address tables, said means further checking whether or not the destination address of said restored information frame has been registered on said second address table, abandoning said information frame if said destination address has been registered thereon, while transferring said information frame to said LAN if said destination address has not been registered on said second address table.

Claim 5

An inter-local area network (LAN) connecting method in which LANs are connected to an asynchronous transfer mode (ATM) switching network by respective bridge devices to effect communication of an information frame between terminals connected to different LANs through said bridge devices and said switching network, wherein logical connections are set between said bridge devices in advance to transfer cells, which are information units of data transfer, said information frame including a destination address, an originating address and an information portion, said information frame being divided into a plurality of cells in said bridge devices so as to be exchanged therebetween and also restored from a plurality of cells exchanged, said cells each including a virtual channel identifier (VCI), each of said bridge device having a first address table on which the addresses of terminals connected to a LAN accommodated in this bridge device are registered and held by learning, and a second address table on which the addresses of terminals connected to LANs accommodated in other bridge devices are registered and held by learning in pairs with identifiers that identify logical connections between this bridge device and the other bridge devices, said method comprising the steps of: checking whether or not the oridinating address of said information frame received from said LAN has been registered on said first address table, and registering, if it has not, said originating address on said first address table; checking whether or not the destination address of said information frame received from said LAN has been registered on said first and second address tables, abandoning said information frame if it has been registered on said first address table, transmitting, if said destination address has not been registered on said first address table but it has been registered on said second address table, said information frame to the bridge device designated by the VCI registered on said second address table, and broadcasting said information frame to all the other bridge devices if said destination address has not been registered on either of said first and second address tables; and checking whether or not the destination address of said restored information frame has been registered on said second address table, abandoning said information frame if it has been registered thereon, checking whether or not the originating address of said restored information frame has been registered on said second address table if said destination address has not been registered thereon, registering said originating address and said VCI on said second address table if said originating address has not been registered thereon, while transferring said information frame to said LAN as it is if said origianting address has been registered on said second address table.

Claim 6

An inter-local area network (LAN) connecting method in which LANs are connected to an asynchronous transfer mode (ATM) switching network by respective bridge devices to effect communication of an information frame between terminals connected to different LANs through said bridge devices and said switching network, wherein logical connections are set between said bridge devices in advance to transfer cells, which are information units of data transfer, said information frame including a destination address, an originating address and an information portion, said information frame being divided into a plurality of cells in said bridge devices so as to be exchanged therebetween and also restored from a plurality of cells exchanged, said cells each including a virtual channel identifier (VCI), each of said bridge device having a first address table on which the addresses of terminals connected to a LAN accommodated in this bridge device are registered and held by learning, and a second address table on which the addresses of terminals connected to LANs accommodated in other bridge devices are registered and held by learning in pairs with identifiers that identify logical connections between this bridge device and the other bridge devices, said method comprising the steps of: checking whether or not the oridinating address of said information frame received from said LAN has been registered on said first address table, and registering, if it has not, said originating address on said first address table; checking whether or not the destination address of said information frame received from said LAN has been registered on said first and second address tables, abandoning said information frame if it has been registered on said first address table, transmitting, if said destination address has not been registered on said first address table but it has been registered on said second address table, said information frame to the bridge device designated by the VCI registered on said second address table, and broadcasting said information frame to all the other bridge devices if said destination address has not been registered on either of said first and second address tables; and checking whether or not the destination address of said restored information frame has been registered on said second address table, abandoning said information frame if it has been registered thereon, checking whether or not the originating address of said restored information frame has been registered on said second address table if said destination address has not been registered thereon, registering said originating address and said VCI on said second address table if said originating address has not been registered thereon, while transferring said information frame to said LAN as it is if said origianting address has been registered on said second address table.

Claim 7

An inter-local area network (LAN) connecting system in which LANs are connected to an asynchronous transfer mode (ATM) switching network by respective bridge devices to effect communication between terminals connected to different LANs through said bridge devices and said switching network, comprising: logical connections set between said bridge devices in advance to transfer cells, which are information units of data transfer; and each of said bridge devices having a first address table on which the addresses of terminals connected to a LAN accommodated in this bridge device are registered and held by learning, a second address table on which the addresses of terminals connected to LANs accommodated in other bridge devices are registered and held by learning in pairs with identifiers that identify logical connections between this bridge device and the other bridge devices, and means for checking the identifier of a received information frame or received cell against said first or second address table to judge the destination in accordance with the registration condition of said first or second address table, and effecting communication on the basis of the result of the judgement.

Claim 8

An inter-local area network (LAN) connecting system in which LANs are connected to an asynchronous transfer mode (ATM) switching network by respective bridge devices to effect communication between terminals connected to different LANs through said bridge devices and said switching network, comprising: logical connections set between said bridge devices in advance to transfer cells, which are information units of data transfer; and each of said bridge devices having a first address table on which the addresses of terminals connected to a LAN accommodated in this bridge device are registered and held by learning, a second address table on which the addresses of terminals connected to LANs accommodated in other bridge devices are registered and held by learning in pairs with identifiers that identify logical connections between this bridge device and the other bridge devices, and means for checking the identifier of a received information frame or received cell against said first or second address table to judge the destination in accordance with the registration condition of said first or second address table, and effecting communication on the basis of the result of the judgement.