Abstract: A ring connection apparatus according to one embodiment is provided with: a frame receiver that receives frames to be transmitted to one of the plurality of ring networks from each of the plurality of networks; and a frame transmitter that transmits each of frames, a passing frame to be transmitted from a device to another device inside said one ring network and a crossing frame to be transmitted to a device in said one ring network from a device in another ring network different from said one ring network, to said one ring network within the range of a band, which is separately determined in advance.

Abstract: A method of providing path protection includes setting a working path and a protection path by identifying, as a single path, a set of a control-purpose virtual network identifier and at least one virtual network identifier that are assigned to one or more users at a section defined as a point-to-point connection in a virtual network, and switching between the working path and the protection path.

Abstract: An arbitrary node that belongs to a virtual LAN sends a request packet including a count value indicating the number of communication hops across nodes to each of its adjacent nodes that belong to the virtual LAN and are adjacent. Upon receiving the request packet, each of the adjacent nodes sends the request packet in which the count value is incremented or decremented to each of its adjacent nodes that belong to the virtual LAN and are adjacent to the node, excluding a sender of the request packet received, and sends a reply packet including the sender's address, an address of the node that is a replying node, and the count value to a given return destination. The return destination collects reply packets sent thereto and keeps track of the topology of the nodes constituting the virtual LAN from information contained in the reply packets.

Abstract: A fault detection device capable of detecting network faults by itself with high accuracy in multi-vendor environments, without the need to interoperate with an associated device according to an identical protocol. A monitoring control packet transmitter generates a fault monitoring control packet and transmits the generated packet to the associated device with which the fault detection device need not interoperate to detect faults according to the same protocol. A transmit packet counter keeps count of the transmitted fault monitoring control packet. A receive packet counter receives a control packet transmitted from the associated device, and keeps count of the received control packet. A fault detector monitors the count of transmitted packets and the count of received packets and, if at least one of the counts remains unchanged for a fixed period of time, judges that a fault has occurred and sends a fault notification to outside.

Abstract: A ring connection apparatus according to one embodiment is provided with: a frame receiver that receives frames to be transmitted to one of the plurality of ring networks from each of the plurality of networks; and a frame transmitter that transmits each of frames, a passing frame to be transmitted from a device to another device inside said one ring network and a crossing frame to be transmitted to a device in said one ring network from a device in another ring network different from said one ring network, to said one ring network within the range of a band, which is separately determined in advance.

Abstract: A repeater and method provides a technique to minimize congestion and packet loss, which may be generated when a fault is detected in a ring type packet network or when the network recovers from such a fault. A repeater having a plurality of ports for transmitting and receiving packets in a ring type network for transmitting the received packets on the basis of an address included in a received packet and a transmitting port database indicating an identifier of a port to transmit the packet having the address as the destination, comprises a control packet processing block to detect reception of a fault notifying packet transmitted from a repeater having detected a fault and a control block to update, upon reception of the fault notifying packet from an immediately adjacent repeater, a port identifier of the transmitting port database having a port identifier of the port having received said fault notifying packet into a port identifier of a port connected to another immediately adjacent repeater.

Abstract: A data relay apparatus stores identification information for identifying itself. A blocking unit blocks a port to avoid an occurrence of a loop path if the data relay apparatus is a master node, and blocks a port connected to a link of the data relay apparatus if a failure occurs to the link. When the link is restored from the failure, a comparing unit compares identification information of other apparatus connected to the link, with the identification information stored. Based on a result of the comparison, a determining unit determines whether the data relay apparatus should be set as a master node.

Abstract: An input line interface device that is used to accommodate packets from a high-speed line efficiently and to reduce a processing load on a back stage caused by routing control. A packet allotting section divides a variable-length packet, allots divided packets to parallel lines, and outputs the packets. A flow group classifying section classifies the packets into flow groups on each of the parallel lines. A sequence number giving section gives the packets sequence numbers corresponding to or independent of the flow groups. A buffering section stores the packets to which the sequence numbers have been given in a buffer or reads out them from the buffer to exercise sequence control over the packets in the flow groups. A flow separating switch separates the packets according to the flow groups and outputs the packets.

Abstract: A packet multiplexing control method and equipment using the method are realized by a simple control method with reduced hardware, enabling to provide low cost, efficient and fair bandwidth control corresponding to traffic characteristic of users. The packet multiplexing control method includes the steps of extracting a header part in each packet data received from a plurality of terminals; learning an address in the extracted header part; and controlling either admission processing or discard processing of the received packet according to the result of learning the address.

Abstract: Packets input from input HWs #0 to #3 to a packet switch device are buried in time slots A through D. The packet switch device alternately switches the input packets in units of time slots, and inputs the packets to two 4×4 switches. The 4×4 switches make normal switching, and distribute the packets to respective output ports. Then, the packets output from the two 4×4 switches after being switched are alternately multiplexed, and output to output HWs #0 through #3. By making switching in units of packets as described above, a process overhead is prevented from being increased, and also expansion can be easily made. Besides, hardware scale can be made small.

Abstract: A method of providing path protection includes setting a working path and a protection path by identifying, as a single path, a set of a control-purpose virtual network identifier and at least one virtual network identifier that are assigned to one or more users at a section defined as a point-to-point connection in a virtual network, and switching between the working path and the protection path.

Abstract: A repeater and method provides a technique to minimize congestion and packet loss, which may be generated when a fault is detected in a ring type packet network or when the network recovers from such a fault. A repeater having a plurality of ports for transmitting and receiving packets in a ring type network for transmitting the received packets on the basis of an address included in a received packet and a transmitting port database indicating an identifier of a port to transmit the packet having the address as the destination, comprises a control packet processing block to detect reception of a fault notifying packet transmitted from a repeater having detected a fault and a control block to update, upon reception of the fault notifying packet from an immediately adjacent repeater, a port identifier of the transmitting port database having a port identifier of the port having received said fault notifying packet into a port identifier of a port connected to another immediately adjacent repeater.

Abstract: A communication apparatus that detects a network failure by itself, without using any particular protocol to interact with other apparatuses in a multivendor virtual LAN (VLAN) environment. The communication apparatus has a group of physical link ports, including first and second ports, to provide physical link connections to an opposite apparatus. A virtual link from the first port to the second port is formed by tunneling through the opposite apparatus. A tagged packet transmission and receiving section transmits outgoing tagged packets from the first physical link port, while receiving incoming tagged packets arriving at the second physical link port. A failure detection section detects a failure on the VLAN by checking whether every tagged packet sent out of the first port can return to the second port via the virtual link that tunnels through the opposite apparatus.

Abstract: A fault detection device capable of detecting network faults by itself with high accuracy in multi-vendor environments, without the need to interoperate with an associated device according to an identical protocol. A monitoring control packet transmitter generates a fault monitoring control packet and transmits the generated packet to the associated device with which the fault detection device need not interoperate to detect faults according to the same protocol. A transmit packet counter keeps count of the transmitted fault monitoring control packet. A receive packet counter receives a control packet transmitted from the associated device, and keeps count of the received control packet. A fault detector monitors the count of transmitted packets and the count of received packets and, if at least one of the counts remains unchanged for a fixed period of time, judges that a fault has occurred and sends a fault notification to outside.

Abstract: The packet switch performs a scheduling process by selecting a unicast packet or a multicast packet to be output from each of N input buffers such that input lines and output lines cannot conflict each other for a unicast packet, and such that the input lines cannot conflict each other for the multicast packet.

Abstract: A scheduling system is capable of causing no deterioration of characteristics even under equal and unequal loads, eliminating the necessity for high-speed repetitive scheduling and complicated arithmetic processes, simplifying its architecture and having its processing speed which does not depend upon a device capability. For attaining this system, an inter-highway pointer is updated to an adjacent line (rightward) when the scheduling for all the lines are finished. If the inter-highway pointer is updated N-times in the same direction (clockwise), the same pointer is updated to an adjacent line in a reverse direction (counterclockwise) in next N-processes of scheduling.

Abstract: A packet switch which can cyclically use ? scheduling process results to determine one of M output lines as a destination of a packet stored in each of N input buffer sections by ? scheduler sections independently performing scheduling processes is disclosed.

Abstract: To achieve QoS control, drop control and multicast control of a variable-length packet at high speed in small scale hardware, a packet divider divides a variable-length packet into fixed-length packets, and an input buffer section stores the divided fixed-length packets into queues by output lines and by QoS classes. A large number of QoS classes are mapped into only two kinds of classes including a guaranteed bandwidth class for which an assigned bandwidth is guaranteed and a best effort class for which a surplus bandwidth is allocated, thereby to achieve scheduling at the input side by an inter-line scheduler. An output buffer section assembles a variable-length packet from fixed-length packets that have been obtained by switching at a switch section in an output buffer section. A QoS control is performed based on a packet length.

Abstract: An arbitrary node that belongs to a virtual LAN sends a request packet including a count value indicating the number of communication hops across nodes to each of its adjacent nodes that belong to the virtual LAN and are adjacent. Upon receiving the request packet, each of the adjacent nodes sends the request packet in which the count value is incremented or decremented, as predetermined, to each of its adjacent nodes that belong to the virtual LAN and are adjacent to the node, excluding a sender of the request packet received, and sends a reply packet including the sender's address (sender address), an address of the node that is a replying node (replying node address), and the count value to a given return destination. The return destination collects reply packets sent thereto and keeps track of the topology of the nodes constituting the virtual LAN from information contained in the reply packets.

Abstract: A packet switch includes an input buffer memory unit having a logic queue corresponding to an output line, a control module for a first pointer indicating a scheduling start input line, a control module for a second pointer indicating a scheduling start output line of scheduling target outlines, a request management control module for retaining transmission request data about a desired output line, a scheduling processing module for starting a retrieval from within plural pieces of transmission request data from the output line indicated by the second pointer, and selecting an output line that is not ensured by other input lines, a packet buffer memory unit for temporarily storing a plurality of fixed-length packets and sequentially outputting the fixed-length packets, a switch unit for switching the fixed-length packets outputted from the packet buffer memory unit, and an address management unit for segmenting an address of the packet buffer memory unit into fixed-length blocks for a plurality of packets, an