| 摘要 |
<p>PROBLEM TO BE SOLVED: To accelerate the switching operation of a communication pathway upon occurrence of a pathway defect in a network system, while facilitating addition of a lower network.SOLUTION: A communication node device 3 for constituting a ring network system S1 is configured so that a control frame transmission mode for transmitting a monitor frame 100a periodically from one port 11, out of two ports 11 belonging to the network system S1, a control frame reception mode for monitoring whether or not the monitor frame 100a is received at the other port 11 in a state where one port 11a out of the two ports 11 is closed, and a control frame relay mode for relaying the monitor frame 100a received at one port 11a out of the two ports 11 to other communication node device 3 connected with the other port 11 can be switched.</p> |
