Patent ID: 8411559

Claim:
A communication control method for double ring networks including a set of two or more transmission stations each respectively configured with a pair of communication ports for communications to be implemented bi-directionally, and mutually connected by said pairs of communication ports thereof in a ring form through a transmission line to implement intercommunications between transmission stations, wherein for a respective transmission station, the method comprising: a step of simultaneously sending transmission frames containing information at a time from paired communication ports of said transmission station; a step of detecting a transmission frame sent from another said transmission station received at one of said paired communication ports; and a step of sending above-noted said transmission frame as repeatable to another communication port being the other with respect to the one communication port, from said other communication port, and for a respective one of adjacent paired said transmission stations out of said set of two or more transmission stations mutually connected in the ring form, the method comprising: a step of having the transmission frame sent from one of said transmission station's communication ports; and a step of performing, for a transmission frame received at a second one of said transmission station's communication ports as it is connected through the transmission line, a detection at this station, and in that said transmission frame to be responded to in accordance with information contained in said transmission frame is kept from being sent, through a repeating from said receiving communication port to the other communication port, from said other communication port, whereby said received transmission frame is kept from arriving at ring-form connected and subsequent transmission stations in a repeating direction thereof, and above-noted transmission frames sent from said transmission station are kept from circulating in a network configured in the ring form.