Abstract: A packet relay apparatus for suppressing a burst transfer of packets being relayed to improve the quality and reliability of packet communication. In the packet relay apparatus, an arrival time measurement block measures the arrival time of an input packet to generate arrival time information; a packet classification block classifies the packet as an output-interval-control packet, which requires output interval control, or a non-output-interval-control packet, which does not require output interval control, to generate classification information; a packet distribution block receives the packet which has been processed and switched and places the packet in an appropriate queue according to the classification information; and a schedule management block performs relay output control in accordance with the arrival time information such that the output intervals of output-interval-control packets become equal to the input intervals obtained when the packets were input to the apparatus.

Abstract: A packet relay apparatus for suppressing a burst transfer of packets being relayed to improve the quality and reliability of packet communication. In the packet relay apparatus, an arrival time measurement block measures the arrival time of an input packet to generate arrival time information; a packet classification block classifies the packet as an output-interval-control packet, which requires output interval control, or a non-output-interval-control packet, which does not require output interval control, to generate classification information; a packet distribution block receives the packet which has been processed and switched and places the packet in an appropriate queue according to the classification information; and a schedule management block performs relay output control in accordance with the arrival time information such that the output intervals of output-interval-control packets become equal to the input intervals obtained when the packets were input to the apparatus.

Abstract: A router includes a plurality of control units connected in parallel, each having an input connected to a receiving interface and an output connected to a transmitting interface, and performing timing control of outgoing packets to the transmitting interface based on header information of incoming packets, the incoming packets being stored in a memory and the stored packets being transmitted to the transmitting interface in order of transmission of the outgoing packets. A distributing unit distributes transmitting sequence information, related to the stored packets in the memory, to other control units. The distributing unit determines whether a packet sequence inversion in the control unit occurs, based on a result of comparison of the transmitting sequence information received and the transmitting sequence information held by the control unit, inhibiting the transmission of the stored packets to the transmitting interface when the packet sequence invention is detected.

Abstract: A packet relay device which realizes a QoS service with higher quality by improving an intra-device policy concerning packet discard. An input-side policing unit measures a first data rate of packets before being switched, and discards at least one of the packets before being switched, when the first data rate exceeds a first bandwidth value which is preset. A switching unit performs switching of the packets on which the input processing is performed. An output-side policing unit receives packets flowing together after being switched, measures a second data rate of a portion of the received packets corresponding to each value of a parameter, compares the second data rate with a second bandwidth value which is preset to be guaranteed for the value of the parameter, and discards at least one packet in the portion of the received packets when the second data rate exceeds the second bandwidth value.

Abstract: A packet communication apparatus using a timer for always completing the transmission of a received packet within a delay assurance time length assurable by itself. The packet communication apparatus notifies information on the delay assurance time length to a destination side packet communication apparatus, while the destination side packet communication apparatus determines a received packet buffering quantity in communication with the origination side packet communication apparatus on the basis of the information notified. This optimizes a received packet buffering quantity in the destination side packet communication apparatus in a packet communication system, thus enabling the assurance of a necessary communication quality at a low cost.

Abstract: A router includes a plurality of control units connected in parallel, each having an input connected to a receiving interface and an output connected to a transmitting interface, and performing timing control of outgoing packets to the transmitting interface based on header information of incoming packets, the incoming packets being stored in a memory and the stored packets being transmitted to the transmitting interface in order of transmission of the outgoing packets. A distributing unit distributes transmitting sequence information, related to the stored packets in the memory, to other control units. The distributing unit determines whether a packet sequence inversion in the control unit occurs, based on a result of comparison of the transmitting sequence information received and the transmitting sequence information held by the control unit, inhibiting the transmission of the stored packets to the transmitting interface when the packet sequence invention is detected.

Abstract: There is provided a communication control method for a network including duplexed ring transmission lines and a plurality of communication controlling devices each accommodating a plurality of terminals and adapted to transmit data sent from any of the terminals and receive data over the ring transmission lines, the communication control method comprising the steps of: causing one communication controlling device to transmit monitoring cells simultaneously over the duplexed transmission lines, the monitoring cells each including a pass indication area for retaining a source address and identification information for identifying a passed communication controlling device; and causing another communication controlling device which receives the monitoring cells respectively from the duplexed transmission lines to relay and circulate the monitoring cells respectively over the duplexed transmission lines after writing in the pass indication area of each of the received monitoring cells data indicative of passage of