Network device, network system, network method, and computer readable medium

A network method of a network device included in a ring-type network system which comprises a plurality of network devices to transmit and receive a frame and which selects a time master serving as a time criterion, from among the plurality of network devices, the network method comprising

• generating a link for communicating the frame, the network method having a frame discarding function of discarding the frame in order to avoid a broadcast storm,
• generating a time distribution path starting at and terminating at the time master, clockwise and counterclockwise of the time master, the time distribution path communicating a time synchronization message out of the frame, the time synchronization message being used for time synchronization of the plurality of network devices, and
• upon acquisition of the time synchronization message, making the time synchronization message to pass through regardless of the frame discarding function.

A non-transitory computer readable medium containing a network program of a network device included in a ring-type network system which comprises a plurality of network devices to transmit and receive a frame and which selects a time master serving as a time criterion, from among the plurality of network devices, the network program causing the network device, being a computer, to execute

• a link process of generating a link for communicating the frame, the link process having a frame discarding function of discarding the frame in order to avoid a broadcast storm,
• a path control process of generating a time distribution path starting at and terminating at the time master, clockwise and counterclockwise of the time master, the time distribution path communicating a time synchronization message out of the frame, the time synchronization message being used for time synchronization of the plurality of network devices, and
• a filtering process of, upon acquisition of the time synchronization message, making the time synchronization message to pass through regardless of the frame discarding function.