Bridge device, method of controlling bridge device, and control program

A layer-2 network, comprising:

• a router;
• and
• a plurality of bridge devices,
• wherein the bridge device that is adjacent to the router among the plurality of bridge devices is set as a root bridge by making a bridge ID of the bridge device smaller than the bridge IDs of other bridge devices;
• and
• the bridge device comprising:
• a router connection state judgment unit which judges whether or not the bridge device is adjacent to the router by comparing, with respect to a Query message representing a message for confirming whether or not there is participation in a multicast group that is sent by the router, a first reception number indicating the number of normal Query messages received and a second reception number indicating the number of abnormal Query messages received, and which outputs an instruction to change the bridge ID when judged that the bridge device is adjacent to the router.

A layer-2 network, comprising:

• a router;
• and
• a plurality of bridge devices, wherein the bridge device that is adjacent to the router among the plurality of bridge devices is set as a root bridge by storing an ID that is smaller than the bridge IDs of other bridge devices in a region where a root ID of a BPDU is stored, wherein
• the bridge device comprising:
• a router connection state judgment unit which judges whether or not the bridge device is adjacent to the router by comparing, with respect to a Query message representing a message for confirming whether or not there is participation in a multicast group that is sent by the router, a first reception number indicating the number of normal Query messages received and a second reception number indicating the number of abnormal Query messages received, and which outputs an instruction to change the bridge ID when judged that the bridge device is adjacent to the router.