Patent ID: 8422366

Claim:
A data transmission device comprising: switches with redundancy, each outputting a frame in its input order; input interfaces, each coupled to each switch, generating frames in which every time data is inputted, input order information indicating the input order is added to the data together with unique information of each input interface and providing the frames generated to the switches in parallel; and at least one output interface sequentially storing the frames outputted from the switches for every unique information and selecting a first arrived frame among the frames stored with same input order information, wherein the output interface stores the frames in association with the switches having outputted the frames, determines that when the frames stored with the same input order information after a first specified time has lapsed from the selecting of the first arrived frame are detected, the switch corresponding to the frames detected is in a congested state and excludes following frames outputted from the switch in the congested state from being selected.