A plurality of subscriber stations and a plurality of switching points are connected in series in a loop circuit transmitting signals in one direction, parallel line sections disposed in parallel with the loop circuit are each connected with two switching points and each switching point contains a switch controlled by a failure detector and adapted for switching between a loop circuit section and a parallel line section. The transmission direction of the parallel line sections corresponds to the direction of the loop circuit; an incoming parallel line section which by-passes one or two immediately preceding switching points and an out-going parallel line section which by-passes one or two immediately succeeding switching points are connected to each switching point.
An optical fiber-ring network is disclosed. The network is capable of operating in the face of the failure of any single node regardless of the particular node failure mechanism, including stuck "on" and stuck "off" transmitters. Each node in the network comprises a main receiver, an alternate receiver, and a transmitter. The main receiver receives data from the immediately adjacent upstream node, while the alternate receiver monitors transmissions from the next preceding upstream node. Each node diagnoses the transmitter in its immediately adjacent upstream neighbor and its own main receiver. If either fails, the node switches from its main receiver to its alternate receiver to bypass the immediately adjacent upstream node, while the rest of the ring remains functional.
A loop-type data transmission/reception network system has a plurality of data processing stations and a single data transmission/reception route which interconnects said stations in a loop for transmitting necessary data between the stations, each of the stations comprising: (a) means for detecting a break-down in the data transmission/reception route between the station itself and the preceding station; (b) means responsive to the detection of a break-down in the data transmission/reception route between the station itself and the preceding station by the detection means for transmitting break-down information to the subsequent station; and means for reversing the transmission direction in the data transmission reception route in accordance with the break-down information transmitted by the break-down information transmitting means.
A digital time division multiplex (TDM) telecommunication network is described wherein the subscriber terminals are located on a common TDM highway and are served from a central office in accordance with the sequencing principle. The flow of information can be switched on branch routes using branching switching devices, a fixed sequence being adhered to in this case, as well.
There is disclosed a data transmission system comprising a first and a second loop transmission line for transferring data in its clockwise and counterclockwise directions, respectively. In each loop transmission line a plurality of transmission control units are connected in series. Further, a plurality of terminal units each are interconnected with its associated first and second transmission control units correspondingly and respectively located in the first and second loop transmission lines. Each of the transmission control units in the first loop transmission line is interconnected to a corresponding one of the transmission control units in the second loop transmission line by a bypass line so as to make a pair, so that a fault in the loop transmission line may be detected and a loop transmission line bypassing the fault point may be established without using any master transmission control unit.
A digital time division multiplex (TDM) telecommunication network is described wherein subscriber terminals are connected to a closed TDM loop which forms branch loops appropriately routed to remote subscriber groups or network sections. The branch loops may be bypassed by a connecting device in the event of a fault.
