Kabushiki Kaisha Toshiba

Yasuhisa Shiobara

Shinya Kono

Yoshito Tobe

A double ring network system configured with two or more transmission stations each including a pair of bi-directionally communicative communication ports, including any adjacent two transmission stations as terminal stations, and any transmission station as a base, as mutually connected in a ring form by communication ports through a transmission line, for intercommunications between transmission stations, in which the transmission stations are each adapted to determine whether or not frame signals are received from adjacent transmission stations, transmit route identifying frame signals for identification of routes to adjacent transmission stations, when having failed in reception, and set own station as a terminal station substituting for a current terminal station, when having received no responses to the route identifying frames from adjacent transmission stations, so they are kept from arriving at ring-like connected subsequent transmission stations.

Double ring network system and communication control method thereof, and transmission station, and program for transmission stations

A data transmitting apparatus comprises a connection section, a signal receiving section, a transmission right acquisition section, and a signal transmitting section. The data transmitting apparatus is connected to a communication system comprising devices that use protocols designed to prevent the collision of frames. Additionally, the data transmitting apparatus accomplishes communication among the devices, enabling transmitting stations incorporated in a network to exchange information. The data transmitting apparatus may transmit frames within a prescibed time, such as in real time, without being influenced by the data communication among the transmitting stations in the communication system.

Data transmitting apparatus, network interface apparatus, and data transmitting system

A data transmission system, including a first sending and receiving control system and a second sending and receiving control system, which may be a media access control system of a CSMA/CD type system including plural terminals having data frame sending and receiving mechanisms connected to the ports of hub units in a star shape configuration, and wherein the hub units of both sending and receiving control systems are connected to each other with signal transmission lines, such that at a certain point in time, one of the plurality of hub units performs a control of the transmission approval function which enables a data frame from a corresponding terminal to be sent to the ports of the hub units in a prescribed sequence. The object of the invention is to achieve a data transmission system, including mutually connected plural hub units, capable of performing a realtime transmission right control function as a single united body even when the hub units of a star-shaped data transmission system are arranged at dispersed locations.

Data transmission system and its control method and multiplexing method

In a data switching method for switching data among data switching apparatuses arranged on an ATM network and interconnected by links along a cell data transmission path, data input to a specified one of the data switching apparatuses from an upstream-side one of the data switching apparatuses along the transmission path is sent out to a downstream-side one of the data switching apparatuses along the transmission path. A branch-system data switching operation for delivering data, which has been input to the specified data switching apparatus from at least one terminal linked to the specified data switching apparatus, to a specified one of the terminals and the data switching apparatuses, is performed separately from a trunk-system data switching operation for delivering data, which has been input to the specified data switching apparatus from the upstream-side data switching apparatus, to the downstream-side data switching apparatus and terminals.

Data switching method and data switching apparatus for efficiently

To improve the method of scheduling data transfer requests based on the transfer completion times to the transfer addresses which are assigned to the data for which transfers are requested. A limit time is assigned as an attribute to the data for which transfer is requested from control system 1. The transmission station which becomes the data station (transmission control processing circuit 12) produces a transfer completion time, taking the limit time as the upper digit, the count value of counter 13 which counts a constant clock as the middle digit and the number inherent to the transmission station as the lower digit, and transfers to the transmission station, which becomes the master station, output request control information which includes the data packet length found from this transfer completion time and the data length to be transferred. The transmission station, which becomes the master station, (transmission control processing circuit 12 and reception control processing circuit 17) determines the order given to output permissions based on the transfer completion times, determines the number of output requests permitted based on the data packet lengths, and schedules output permissions for the output requests of multiple transmission stations.

Network system transmission control method

A data transmission apparatus comprises a data receiving section, a memory section, an acquisition section, a comparison section, a determination section and a discard section. The comparison section compares transmission time period data consisting of an expected transmission time period read from the memory section and a present time point, with the receiving time limit of a packet acquired by the acquisition section. The determination section determines whether or not the packet will be received by a receiver of destination by the receiving time limit, on the basis of the comparison result. The discard section discards the packet if the determination section determines that the packet will not be received by the receiver of destination by the receiving time limit.

Data transmission method and apparatus applicable to network system

A data communications system has nodes provided with data processing apparatus disposed at a number of points which are mutually separated at a distance with optical transmission cables and which are provided with a FDDI (fiber distributed data exchange interface) for optical local area networks for transmitting/receiving at either high-speed or low-speed, data between the data processing apparatus, control apparatus and peripheral apparatus.

Data communications system using a fiber distributed data exchange

Each node in a network of nodes calculates and holds a data transmission processing time of each node, a transfer time of data and a reception processing time of the data on the basis of past data transmission/reception information. A transmission request sequence for a plurality of data in a first node is rearranged responsive to a transmission request for specific data from a first node to a second node. This rearranging process is done on the basis of a difference between a request timing at which time the specific data is required by the second node and the sum of: 1) a reception processing time of the second node, the reception processing time being held in the first transmission reception node; 2) a transfer time required for transferring data from the first node to the second node, the transfer time being held in the first node; and 3) a current timing, thereby determining a transmission processing sequence. Transmission processing is performed in accordance with the determined transmission processing sequence. Not only may data be ordered within each node with regard to both transmission and reception, but also data may be ordered for transmission throughout the entire network.

Timely processing of transmission and reception requests in a multi-node

A data transmission system using media access control of a token-passing type including multiple nodes connected to a common transmission path, wherein each node transmits data in a predetermined period in order in a broadcasting or multicasting manner, and each non-transmitting node receives and stores the data in a receive buffer. Each node includes circuitry for receiving a data frame and detecting whether or not a destination address included in the received data frame is the same as its own destination address, and transmitting a data frame reception end signal when it is determined that its own destination address has been received. A DMA controller extracts predetermined received data included in the received data frame in response to the data frame reception end signal and transmits the predetermined received data to a receive buffer where the predetermined received data are stored. An address conversion memory stores an address of the received data stored in the receive buffer, and converts a specific address externally input to access the received data in the receive buffer into the address of the receive buffer at which the received data is stored, thereby generating a conversion address. A receive and transmission control processing circuit updates the address of the received data stored in the receive buffer, causes the updated address to be stored in the address conversion memory, and accesses the received data in the receive buffer with the conversion address to read out the received data.

Direct transfer from a receive buffer to a host in a token-passing type

A data transmission system has multiple nodes connected to a common transmission medium. Each of the multiple nodes transmits data and the other nodes receive and store the data through the common transmission medium. The received data is read out for information exchange among the nodes. The node has transceiver circuitry for receiving a data frame and transmitting the data frame, receive and transmission control circuitry, receive data frame transmission control circuitry, a receive buffer, an external interface and address conversion memory circuitry. The receive and transmission control circuitry receives a data frame from the transceiver, detects whether or not the data frame designates that node and is received without errors, and transmits a data frame reception start signal and a data frame reception end signal. The data frame transmission control circuitry extracts predetermined received data included in the received data frame in response to the data frame reception start signal, and transmits the predetermined received data in response to the data frame reception end signal. The receive buffer receives and stores the predetermined received data, and the external interface provides a specific address. The address conversion memory circuitry stores an address of the received data stored in the receive buffer and converts the specific address into the address of the received data, thereby generating a conversion address. This considerably shortens the time required to transmit the received data, and improves data transmission speed in the whole system.

Data transmission system

This disclosure is for an improved data synchronous transfer apparatus configured from fiber distributed data interfaces (FDDI) provided with processing functions for synchronous services and asynchronous services are disposed at each node, where these nodes are connected via transfer paths into a ring shape and transfer synchronous data frames. In this system, each node that is a primary stations for synchronizing the set time of the synchronous data frames is provided with a synchronization signal generation circuit that generates a synchronization signal for each set time an external time signal is received from either itself or externally, a token detection circuit in order to detect the receipt of a token that rotates around a transfer path connected in a ring shape, a counter that counts down a predetermined value and that is reset for each generation of the synchronization signal, a frame length conversion circuit, that creates a dummy data frame having a time equivalent in length to a value remaining value on the counter at the time when there is the detection of the receipt of the token that has rotated around the ring-shaped transfer path and has returned, and a transfer control means that synchronizes the transfer start time of the synchronous data frame transferred from the node of the primary station with the set time by the transfer of the dummy data frame prior to the transfer of the synchronous data frame.

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Nishitokyo, Japan

Yasuhisa Shiobara