Abstract: An apparatus includes line interface cards coupled to a plurality of paths, a first processor configured to control the line interface cards, and a controller including a second processor. The second processor is configured to detect notification information from the line interface cards and determine whether the detected notification information is priority path notification information indicating information on a priority path having a high priority level among the plurality of paths, and transfer the priority path notification information to the first processor, with a higher priority than non-priority path notification information indicating information on a non-priority path other than the priority path.

Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: A frame transmission system includes a frame transmitter and a frame receiver. The frame transmitter includes a frame fragmentation unit and a reproduction header appending unit. The frame fragmentation unit fragments an input frame and outputs transfer frames when the length of the input frame exceeds a predetermined fragmentation reference frame length, and does not fragment the input frame and outputs the input frame as a transfer frame when the length of the input frame is less than or equal to the fragmentation reference frame length. The reproduction header appending unit appends a reproduction header to the transfer frames outputted from the frame fragmentation unit. Here, the reproduction header being required when the transfer frames are reproduced at a receiving side. The reproduction header appending unit varies the header length of the reproduction header to be appended to the transfer frame, according to the length of the input frame.

Abstract: A packet transmission apparatus includes: a plurality of communication ports; a switch for switching packets; a storage unit which stores a plurality of queues for respectively holding packets to be output from the plurality of communication ports; and a stop signal generating unit. The stop signal generating unit generates a stop signal for stopping packets directed to one of the communication ports from being input into the switch, if the amount of packets held in the queue for the one communication port is equal to or larger than a certain first threshold value, and if the sum of the amounts of packets held in the plurality of queues is equal to or larger than a certain second threshold value.

Abstract: In a communication apparatus, a write controller writes received data in a temporary memory which serves as short-time storage. A read controller reads data out of the temporary memory. A discard controller controls discard operation of the data read out of the temporary memory.

Abstract: A multicast packet readout control method is disclosed. An input multicast packet is temporarily stored in a multicast queue of a packet buffer. The multicast packet is read from the multicast queue, and converted into a unicast packet addressed to each of the destinations of the multicast packet. The converted unicast packet is stored in a unicast queue of the packet buffer. The converted unicast packet is then read from the unicast queue and transmitted to the destination.

Abstract: A data communication apparatus has a data retainer, a retain state manager, a guaranteed bandwidth manager, a surplus bandwidth manager managing outputting of output data having a destination retained in the data retainer to an output line on a per-destination basis when the output data is outputted to the output line with the use of a surplus bandwidth that is a surplus over a sum of guaranteed bandwidths, and a scheduler scheduling outputting of data retained in the data retainer to the output line, based on results of managements by the guaranteed bandwidth manager and the surplus bandwidth manager and a retain state managed by the retain state manager. The apparatus manages the bandwidth with improved accuracy at the time of communication using a surplus bandwidth.

Abstract: A packet transmission apparatus includes: a plurality of communication ports; a switch for switching packets; a storage unit which stores a plurality of queues for respectively holding packets to be output from the plurality of communication ports; and a stop signal generating unit. The stop signal generating unit generates a stop signal for stopping packets directed to one of the communication ports from being input into the switch, if the amount of packets held in the queue for the one communication port is equal to or larger than a certain first threshold value, and if the sum of the amounts of packets held in the plurality of queues is equal to or larger than a certain second threshold value.

Abstract: In a packet transmission method and device, when a received packet is written in a packet buffer, an address of the packet buffer is stored as a read address for each destination corresponding to a physical port and storing information of the received packet. The read address of a destination designated by the received packet information is read and saved when the received packet is read out of the packet buffer in accordance with a scheduling control. Then, the saved read address is taken out in accordance with an arbitration control and a received packet corresponding to the saved read address is read from the packet buffer.

Abstract: A data communication apparatus has a data retainer, a retain state manager, a guaranteed bandwidth manager, a surplus bandwidth manager managing outputting of output data having a destination retained in the data retainer to an output line on a per-destination basis when the output data is outputted to the output line with the use of a surplus bandwidth that is a surplus over a sum of guaranteed bandwidths, and a scheduler scheduling outputting of data retained in the data retainer to the output line, based on results of managements by the guaranteed bandwidth manager and the surplus bandwidth manager and a retain state managed by the retain state manager.

Abstract: In a communication apparatus, a write controller writes received data in a temporary memory which serves as short-time storage. A read controller reads data out of the temporary memory. A discard controller controls discard operation of the data read out of the temporary memory.

Abstract: In a packet transmission method and device, when a received packet is written in a packet buffer, an address of the packet buffer is stored as a read address for each destination corresponding to a physical port and storing information of the received packet. The read address of a destination designated by the received packet information is read and saved when the received packet is read out of the packet buffer in accordance with a scheduling control. Then, the saved read address is taken out in accordance with an arbitration control and a received packet corresponding to the saved read address is read from the packet buffer.

Abstract: An optical network unit and an optical line terminal which efficiently control the data receiving and dechurning processes in a passive optical network. In a churning parameter memory subsystem, a first memory bank stores churning parameters that are currently used, while a second memory bank stores updates made to the churning parameters. Under the control of the churning parameter memory subsystem, those first and second memory banks change their roles with each other at a churning key updating time point. A data dechurning unit receives a data stream consisting of a plurality of frames and dechurns the information contained in the data stream, according to the stored churning parameters. When an update is done to the parameters in a certain frame, the data dechurning unit makes the update effective at the next frame, thus starting data dechurning operations from the next frame.

Abstract: A multicast packet readout control method is disclosed. An input multicast packet is temporarily stored in a multicast queue of a packet buffer. The multicast packet is read from the multicast queue, and converted into a unicast packet addressed to each of the destinations of the multicast packet. The converted unicast packet is stored in a unicast queue of the packet buffer. The converted unicast packet is then read from the unicast queue and transmitted to the destination.

Abstract: An optical network unit and an optical line terminal which efficiently control the data receiving and dechurning processes in a passive optical network. In a churning parameter memory subsystem, a first memory bank stores churning parameters that are currently used, while a second memory bank stores updates made to the churning parameters. Under the control of the churning parameter memory subsystem, those first and second memory banks change their roles with each other at a churning key updating time point. A data dechurning unit receives a data stream consisting of a plurality of frames and dechurns the information contained in the data stream, according to the stored churning parameters. When an update is done to the parameters in a certain frame, the data dechurning unit makes the update effective at the next frame, thus starting data dechurning operations from the next frame.

Abstract: An optical network unit and an optical line terminal which efficiently control the data receiving and dechurning processes in a passive optical network. In a churning parameter memory subsystem, a first memory bank stores churning parameters that are currently used, while a second memory bank stores updates made to the churning parameters. Under the control of the churning parameter memory subsystem, those first and second memory banks change their roles with each other at a churning key updating time point. A data dechurning unit receives a data stream consisting of a plurality of frames and dechurns the information contained in the data stream, according to the stored churning parameters. When an update is done to the parameters in a certain frame, the data dechurning unit makes the update effective at the next frame, thus starting data dechurning operations from the next frame.

Abstract: In an ATM cell multiplexer which multiplexes ATM cells outputted from a plurality of cards, sequential cell arrival numbers common to the ATM cells outputted from a plurality of cards are added to each of the cells to be written in memories, and the read side checks a sequentiality of the cell arrival numbers whereby the ATM cells are read in the order of arrival and the cell arrival number at that time is used as the cell arrival number to be checked at the next read time. Also, when any of the cards is pulled out, a card not pulled out is operated normally and an address counter of only the pulled-out card is cleared. Even when non-sequentiality of the cell arrival numbers occurs due to the clearance of the address counter, the maximum cell arrival number is set to the value which enables the oldest cells to be read first.

Abstract: An optical subscriber line terminal unit and a state transition control method are provided which are capable of stabilizing operation. State information storing means, which is a nonvolatile memory, stores state information about the unit. Startup preparatory state shifting means causes a shift to a startup preparatory state at startup. Flag setting means sets an emergency stop state flag during the period of the startup preparatory state if it is judged based on the state information that a state before the startup is an emergency stop state. State transition control means causes a shift from the startup preparatory state to the emergency stop state if the emergency stop state flag is set, and causes a shift from the startup preparatory state to an initial state if the emergency stop state flag is not set.

Abstract: A delay adjustment unit and optical network unit which efficiently adjust the delay time of upstream data to improve the quality of data transmission services. Upstream transmission data is segmented into small data blocks. A downstream receiver receives control information on which upstream data blocks are granted or not granted to the unit. It also received an equalization delay update request that commands the unit to update its current equalization delay parameter. When this equalization delay update request is received, a delay adjustment controller controls the delay of each data block, depending on whether the transmission of each subsequent data block is granted. An upstream transmitter then transmits the granted data blocks with the adjusted delay times.

Abstract: An optical disc record and playback apparatus is provided in which it is possible to record and play back information on erasable discs, as well as write-once discs. When a disc is first inserted into the record and playback apparatus, data written on a control track of the disc is read to identify whether the disc is erasable or write-once. Optimum record and playback parameters are then set depending upon the type of disc. Another aspect of the invention relates to an optical disc in which data representative of the optical sensitivity of the disc is recorded thereon during manufacture. The data is read by the record and playback apparatus and used to adjust the optical recording power so as to compensate for differences in optical sensitivities of different discs.