Fujitsu Corporation

Kou Takatori

Kenichi Kawarai

Yasushi Sasagawa

Masami Doukai

Kazuyuki Tajima

Kazuto Nishimura

Masaki Hirota

Hiroyuki Kaneko

Yasushi Sasakawa

A method for preventing a control packet loop in a network realizing node redundancy or circuit redundancy based on a rapid spanning tree protocol or a multiple spanning tree protocol is disclosed. The method includes the steps of: detecting a loop of a control packet of the rapid spanning tree protocol or the multiple spanning tree protocol; and discarding the control packet by which the loop is detected so as to prevent occurrence of the loop of the control packet.

Method for preventing control packet looping and bridge apparatus using the method

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.

Method and apparatus for keeping track of virtual LAN topology in network of nodes

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.

Fault detection device

When a control packet is transmitted/received among devices that support a spanning tree protocol (STP), a receiving side device temporarily stores a received control packet in a buffer. When the transmission of a control packet from a transmitting side device is stopped, the control packet stored in the buffer is transferred to a STP processing unit in a specific cycle. Alternatively, the transmitting side device autonomously transmits a control packet for a specific period at specific intervals from when the STP processing unit stops its operation until it restarts the operation according to an instruction to start an automatic transmission.

Apparatus and method for processing control packet in spanning tree protocol

An optical crossconect device comprises an optical switch, input optical level monitoring unit for monitoring optical levels of optical signals supplied to there to, signal generating unit for generating a monitoring signal to monitor the optical switch, input optical signal selecting unit for selecting the monitoring signal generated by the monitoring signal generating unit provided between the optical transmission signal input unit and the optical switch and for supplying the selected optical signal to the optical switch, and input optical signal controlling unit for controlling the input optical signal selecting unit based on an output of the input optical level monitoring unit.

Growing community of inventors

Kawasaki, Japan

Kou Takatori