Spanning tree bridge and route change method using the same

摘要

A controller changes a blocked port to a forwarding state when a link down or change of the representative bridge is detected and a receiving port of a bridge settled in the root bridge is a blocked port. When the bridge itself is not settled in a root bridge, a transmitter transmits to another bridge a TCN-BPDU that, when the bridge itself has received a BPDU inferior to itself BPDU, the representative bridge changes. A transmitter transmits to all other bridges a TC detection flag set BPDU when the bridge itself has received a TCN-BPDU and the bridge itself is settled in a root bridge. When the bridge itself is not settled in a root bridge and the bridge itself has received the TC detection flag set BPDU, such BPDU is transmitted in a direction other than root bridge direction, and the contents of a forwarding table of the bridge itself are deleted.