Ring type ATM network system

A ring type ATM network including a plurality of bode equipments interconnected through a dual ring including a primary ring and a secondary ring having mutually opposed directions, the ring type ATM network system comprising the steps of:

• using a fixed-length cell having a combination value of a virtual path and a virtual connection as an identifier;
• and
• setting two paths identified by the identifier of a cell corresponding to the respective directions of the dual ring between optional two node equipments, and defining one of the two paths as a current system path and defining the other path as a stand-by system;
• wherein a cell transmitting node equipment transmits the cell to both the current system path and the stand-by system path, a cell relaying node equipment relays the cell at a time of receiving the cell by referring to the identifier of the cell, and a cell receiving node equipment receives the cell by selecting one of the two paths including the current system path and the stand-by path so as to transmit only the one cell which is received on the selected one of the two paths to an ATM terminal via an ATM interface;
• and
• wherein a specific node equipment on the dual ring is regarded as the farthest upstream node equipment in the primary ring and as the farthest downstream node equipment in the secondary ring, the farthest downstream node equipment in the primary ring being positioned in the farthest upstream of the secondary ring, the primary ring and the secondary ring having as databases information associated with the order of the node equipments from the farthest upstream to the farthest downstream, the cell transmitting node equipment transmitting a cell having the same data to the two paths at a time of multicast, the node equipment positioned in the farthest downstream of both the rings, instead of setting the virtual connection assigned for the multicast in a downstream direction of the ring, receiving the cell to refer to the identifier of the cell so as to transmit the cell to an ATM terminal via an ATM interface without relaying the cell, the receiving node equipment on the paths being set in a state in which the cell can be received from the two paths, and receiving the cell to refer to the identifier of the cell so as to relay and transmit the cell to an ATM terminal via an ATM interface.

A ring type ATM network system including a plurality of node equipments interconnected through a dual ring including a primary ring and a secondary ring having mutually opposed directions, the ring type ATM network system comprising the steps of:

• using a fixed-length cell having a combination value of a virtual path and a virtual connection as an identifier;
• and
• setting two paths identified by the identifier of a cell corresponding to the respective directions of the dual ring between optional two node equipments, and defining one of the two paths as a current system path and defining the other path as a stand-by system;
• wherein a cell transmitting node equipment transmits the cell to both the current system path and the stand-by system path, a cell relaying node equipment relays the cell at a time of receiving the cell by referring to the identifier of the cell, and a cell receiving node equipment receives the cell by selecting one of the two paths including the current system path and the stand-by path so as to transmit only the one cell which is received on the selected one of the two paths to an ATM terminal via an ATM interface;
• wherein each node equipment has two cell switches, one cell switch having input-output corresponding to the primary ring, and the other cell switch having input-output corresponding to the secondary ring, the ATM interface mounted in each node equipment and connected to the ATM terminal so as to have input-output for each of the two cell switches, and the cell transmitting node equipment transmitting the cell to both the current system path and the stand-by system path by duplicating the cell in the ATM interface so as to transmit the cell having the same data to the two cell switches;
• and
• wherein a specific node equipment on the dual ring is regarded as the farthest upstream node equipment in the primary ring and as the farthest downstream node equipment in the secondary ring, the farthest downstream node equipment in the primary ring being positioned in the farthest upstream of the secondary ring, the primary ring and the secondary ring having as databases information associated with the order of the node equipments from the farthest upstream to the farthest downstream, the cell transmitting node equipment transmitting a cell having the same data to the two paths at a time of multicast, the node equipment positioned in the farthest downstream of both the rings, instead of setting the virtual connection assigned for the multicast in a downstream direction of the ring, receiving the cell to refer to the identifier of the cell so as to transmit the cell to an ATM terminal via an ATM interface without relaying the cell, the receiving node equipment on the paths being set in a state in which the cell can be received from two paths, and receiving the cell to refer to the identifier of the cell so as to relay and transmit the cell to an ATM terminal via an ATM interface.