Abstract: There is disclosed an ATM communication apparatus including an SAR module for executing the processing of a low level layer in an ATM communication network, and a processing unit for executing the processing of a high level layer in the ATM communication network, for the purpose of realizing the function of converting an ATM cell which is a unit of information transmission in the ATM communication network, into an IP packet adapted to a communication protocol of a computer network, and the function of converting the IP packet to ATM cells. Segmentation and reassembly of the IP packet is executed in the SAR module. Thus, congestion of data between the SAR module and the processing unit can be reduced, so that the throughput from the input of the ATM cells to the output of the IP packet and from the input of the IP packet to the output of the ATM cells can be elevated.

Abstract: In an ATM network, a source end system is connected through multiple virtual channels to destination end systems to exchange resource management (RM) cells at periodic intervals and transmit data cells at allowed cell rates (ACRs) respectively set for the virtual channels. The source end system transmits a forward RM cell through an associated virtual channel, and determines a sum of ACR values of the virtual channels in response to receipt of a backward RM cell through the associated virtual channel and compares the sum of ACR values with a predetermined capacity of the access link. The source end system resets a current ACR value of the associated virtual channel equal to a lower-than-previous value when the sum of ACR values is in excess of the predetermined link capacity. In one embodiment, the sum of ACR values is divided by the predetermined link capacity to produce a link load value and the ACR value is reset according to the link load value.

Abstract: In the server control section, the number of virtual channel wherein data is being transmitted is counted per service class. The data output rate from each service class corresponds to the number of counted virtual channels in each service class.

Abstract: In an asynchronous transfer mode switched network, a source terminal sends a burst of data cells and a control cell at periodic intervals through network nodes to a destination terminal. Each network node includes a first buffer and a second buffer, and incoming data cells are stored into the first buffer and incoming control cells are stored into the second buffer. A transmit controller is connected to the first and second buffers for forwarding cells in the first and second buffers in a downstream direction with priority given to the control cells in the second buffer over the data cells in the first buffer. A congestion detector is connected to the first buffer for writing a congestion indication into a control cell which is either stored in or forwarded from the second buffer when the first buffer is filled to a predetermined storage level.

Abstract: In the congestion control method, when a queue length of a node in a virtual channel set up in an ATM network is a first threshold or more, a source terminal in the virtual channel is instructed to decrease a transmission rate. When the queue length of a node is a second threshold or more which is greater than the first threshold, there is halted the transmission of data cells from the preceding nodes or source terminals to the bottleneck node. In a method of decreasing the transmission rate, congestion data is added to the header of a data cell passing through a node where the data cell queue is the first threshold or more, and the destination terminal which has received the data cell containing the congestion data transmits a rate decreasing control cell to the source terminal through the network. Receiving the rate decreasing control cell, the source terminal lowers the transmission rate.

Abstract: In an ATM network using a burst-level band-width allocation, a source terminal reserves, before a burst transmission, band-widths according to a peak rate of the burst and then sends the burst therethrough. When the transmission is finished, the band-widths are released. Where there exists a link to which the peak rate is not assigned, a non-reserving acknowledgement signal (NACK) is sent to the terminal and the reserved band-widths are released. On receiving the NACK, the terminal allocates a band-width with peak rate lower than that of the first request after a back-off time has elapsed, thereby minimizing the probability of a blocked transmission. The source terminal declares a minimum band-width together with the peak rate (maximum band-width) in the band-width request operation. Each node allocates the peak rate when the remaining band-width of a link controlled by the node is sufficient to allocate the peak rate.

Abstract: In the packet switching apparatus of the present invention, packets are inputted, parallel-expanded by a serial-parallel converter, multiplexed on a time division multiplexer, and address information of the packets is discriminated by address filters provided corresponding to the output ports. The address filters receive packets carrying relevant addresses and transmit them to corresponding buffers for storage. The buffers monitor the number of stored packets, and according to the results of comparison of the number of stored packets and buffer capacity, send control signals to reserve memory control assemblies to effect connection and disconnection between the reserve memories and the buffers. The stored packets are then sent from the buffers to the output ports.