Abstract: A system includes a plurality of computers interconnected by a network including one or more switching nodes. The computers transfer messages over virtual circuits established thereamong. A computer, as a source computer for one or more virtual circuit(s), schedules transmission of messages on a round-robin basis as among the virtual circuits for which it is source computer. Each switching node which forms part of a path for respective virtual circuits also forwards messages for virtual circuits in a round-robin manner, and, a computer, as a destination computer for one or more virtual circuit(s), schedules processing of received messages in a round-robin manner. Round-robin transmission, forwarding and processing at the destination provides a degree of fairness in message transmission as among the virtual circuits established over the network.

Abstract: A system includes a plurality of computers interconnected by a network including one or more switching nodes. The computers transfer messages over virtual circuits established thereamong. A computer, as a source computer for one or more virtual circuit(s), schedules transmission of messages on a round-robin basis as among the virtual circuits for which it is source computer. Each switching node which forms part of a path for respective virtual circuits also forwards messages for virtual circuits in a round-robin manner, and, a computer, as a destination computer for one or more virtual circuit(s), schedules processing of received messages in a round-robin manner. Round-robin transmission, forwarding and processing at the destination provides a degree of fairness in message transmission as among the virtual circuits established over the network.

Abstract: A system includes interconnected computers and switching nodes. A source computer for the virtual circuits schedules message transmissions on a round-robin basis. Each switching node also forwards messages in a round-robin manner, and a destination computer schedules processing of received messages in a round-robin manner. In addition, messages are transmitted in cells to reduce delays in short messages if long messages are transmitted for one virtual circuit before transmission of a short message for another virtual circuit. For each virtual circuit, the destination computer and each switching node can generate a virtual circuit flow control message to temporarily limit transmissions if the resources being taken up by messages exceed predetermined thresholds. In addition, each switching node or computer can generate link flow control messages for transmission to neighboring devices to temporarily limit transmissions if the resources taken up by all virtual circuits exceeds predetermined thresholds.

Abstract: A network includes devices such as computers and the like, interconnected by switching nodes. The devices are identified by globally-unique identifiers, such as Ethernet MAC addresses or the like. At least some of the devices are configured to determine the topology of the network. In determining the network topology, a device operates in a series of iterations, in each iteration transmitting a request message over a path to determine whether an additional entity is present in the network. If an additional entity is present at the end of the path defined in the request message, the entity will generate a response, which is provided to the device. The device, on receiving the response, will add information concerning the entity to a network topology database, which it maintains to define the topology of the database. At least some of the devices, as they discover additional switching nodes in the network, will attempt to configure the switching nodes.

Abstract: A system includes a plurality of computers interconnected by a network including one or more switching nodes. The computers transfer messages over virtual circuits established thereamong. A computer, as a source computer for one or more virtual circuit(s), schedules transmission of messages on a round-robin basis as among the virtual circuits for which it is source computer. Each switching node which forms part of a path for respective virtual circuits also forwards messages for virtual circuits in a round-robin manner, and, a computer, as a destination computer for one or more virtual circuit(s), schedules processing of received messages in a round-robin manner. Round-robin transmission, forwarding and processing at the destination provides a degree of fairness in message transmission as among the virtual circuits established over the network.

Abstract: A system includes a plurality of computers interconnected by a network including one or more switching nodes. The computers transfer messages over virtual circuits established thereamong. A computer, as a source computer for one or more virtual circuit(s), schedules transmission of messages on a round-robin basis as among the virtual circuits for which it is source computer. Each switching node which forms part of a path for respective virtual circuits also forwards messages for virtual circuits in a round-robin manner, and, a computer, as a destination computer for one or more virtual circuit(s), schedules processing of received messages in a round-robin manner. Round-robin transmission, forwarding and processing at the destination provides a degree of fairness in message transmission as among the virtual circuits established over the network.

Abstract: A fault-isolating digital data processing apparatus includes plural functional units that are interconnected for point-to-point communications by a plurality of buses. The functional units monitor the buses to which they are attached and signal the other units in the event there are bus communication errors. The functional units can simultaneously enter into an error isolation phase, e.g., in response to a bus error signaled by one of the units. During this phase, each unit transmits test data (e.g., predetermined patterns of O's and 1's) onto at least one of its attached buses. The functional units continue to monitor the buses and to signal bus errors while the test data is being transmitted. In addition to signaling bus errors, the functional units can signal unit-level (or "board") faults when they detect fault in their own operation.