Patent ID: 7719956

Claim:
A failure notification method of a trunk network in which a plurality of nodes is connected together; the failure notification method comprising steps of: classifying external connection ports of said plurality of nodes into groups in advance, and setting in said nodes the correspondence of said external connection ports and said groups; upon detecting a change in the state of said external connection port in any node, transmitting state information, which includes the state of the groups to which the external connection port belongs, from that node to the other nodes that make up said trunk network; in said other nodes that have received said state information, forcibly changing the states of external connection ports that belong to said groups in accordance with the states of said groups that are included in said state information; and setting a control attribute for determining whether states of external connection ports are to be changed upon receiving state information of groups to which the external connection ports belong, wherein: in addition to the correspondence of said external connection ports and said groups, a notification attribute is set in said plurality of nodes, said notification attribute determining whether, when a change occurs in the state of an external connection port, state information of that group is to be reported to said other nodes; in said plurality of nodes, the states of groups, to which belong external connection ports in which said notification attribute has been set for notification, are managed as group states of their own nodes; in a node that has detected a change in the state of the external connection port, if the notification attribute of the external connection port in which the state has changed is set for notification, the group states of its own node of groups that correspond to the external connection port are caused to change, whereby the state information of the group is reported to said other nodes; in said plurality of nodes, the group states of other nodes that show the states of groups to which belong external connection ports in said other nodes in which said notification attribute is set for notification are managed in correspondence with said other nodes based on notification from said other nodes; in said plurality of nodes, the reachability of packets with said other nodes is monitored; in nodes in which changes in reachability with other nodes has been detected, the group states of other nodes that correspond to the other nodes in which reachability has changed are caused to change; and the states of external connection ports are forcibly changed in accordance with the changes in said group states of other nodes.