Patent ID: 6891808
Filing Date: 2005-05-10
Classification: H04L

Abstract:
1. A spanning tree bridge having a predetermined algorithm and protocol which is employed in a network containing a redundant route caused by a plurality of spanning tree bridges having the same predetermined algorithm and protocol as each other, wherein one of the spanning tree bridges is settled in a root bridge, said spanning tree bridge comprising: first detection means for detecting a link down of a root port that provides a shortest route to said root bridge; second detection means for detecting a change of a representative bridge of a receiving port from information on Configuration Bridge Protocol Data Units (BPDU) received from another bridge; means for, when the first detection means detects a link down of the root port, settling the spanning tree bridge itself in the root bridge; means for, when a receiving port of the spanning tree bridge settled in the root bridge is a blocked port, and when one of (i) the first detection means detects a link down of the root port and (ii) the second detection means detects a change of the representative bridge, changing the blocked port to a forwarding state; means for, when the spanning tree bridge itself is not settled in the root bridge and receives a BPDU from a representative port of a representative bridge of a receiving port inferior to its own BPDU, transmitting to another bridge a Topology Change Notification BPDU (TCN-BPDU) that the representative bridge has changed; means for, when the spanning tree bridge itself is settled in the root bridge arid receives a TCN-BPDU from another bridge, transmitting to all other bridges a BPDU in which a Topology Change (TC) detection flag is set; and means for, when the spanning tree bridge itself is not settled in the root bridge and receives a BPDU in which the TC detection flag is set, transmitting the BPDU in a direction other than a root bridge direction, and deleting content of a forwarding table of the spinning tree bridge itself.