Abstract: A route bypassing a root node is constructed in a network in which a spanning tree is formed. A received frame is sent out on a designated port as well as on a root port by using a designated-port data send-out function, provided that a transmitting port for the received frame is learned on the root port. When a frame is received on a blocking port, a transmitting port for a frame whose destination matches the source address of the received frame is temporarily learned on the blocking port by using a blocking-port learning function, on the condition that the destination of the received frame is already learned on some other port. When a frame whose destination matches the temporarily learned address is received, the temporary learning is changed to normal learning by using a temporarily learned address-based data transfer function.

Abstract: A method of connecting a line concentrator to other line concentrators in a switching system, wherein a switching unit accommodates the line concentrator is provided. The method includes the steps of analyzing a call received by the switching unit through the line concentrator, and connecting lines that are accommodated by the line concentrator and are connected to the other line concentrators without connecting through the switching unit when the call is detected to be made between the line concentrator and the other line concentrators. Thus, a call can be made to a specific dial number without connecting through the switching unit provided in the switching system. Additionally, a call can also be made by use of another switching unit when a communication path between the switching unit and the line concentrator is overcrowded.

Abstract: A route bypassing a root node is constructed in a network in which a spanning tree is formed. A received frame is sent out on a designated port as well as on a root port by using a designated-port data send-out function, provided that a transmitting port for the received frame is learned on the root port. When a frame is received on a blocking port, a transmitting port for a frame whose destination matches the source address of the received frame is temporarily learned on the blocking port by using a blocking-port learning function, on the condition that the destination of the received frame is already learned on some other port. When a frame whose destination matches the temporarily learned address is received, the temporary learning is changed to normal learning by using a temporarily learned address-based data transfer function.

Abstract: A method of connecting a line concentrator to other line concentrators in a switching system, wherein a switching unit accommodates the line concentrator is provided. The method includes the steps of analyzing a call received by the switching unit through the line concentrator, and connecting lines that are accommodated by the line concentrator and are connected to the other line concentrators without connecting through the switching unit when the call is detected to be made between the line concentrator and the other line concentrators. Thus, a call can be made to a specific dial number without connecting through the switching unit provided in the switching system. Additionally, a call can also be made by use of another switching unit when a communication path between the switching unit and the line concentrator is overcrowded.