Patents by Inventor Masami Doukai
Masami Doukai has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8199639Abstract: 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.Type: GrantFiled: January 24, 2006Date of Patent: June 12, 2012Assignee: Fujitsu LimitedInventors: Masami Doukai, Ko Takatori, Kenichi Kawarai
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Patent number: 7957267Abstract: 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.Type: GrantFiled: June 20, 2005Date of Patent: June 7, 2011Assignee: Fujitsu LimitedInventors: Yasushi Sasagawa, Kenichi Kawarai, Masami Doukai, Kou Takatori
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Patent number: 7860031Abstract: 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.Type: GrantFiled: March 30, 2004Date of Patent: December 28, 2010Assignee: Fujitsu LimitedInventors: Yasushi Sasagawa, Masami Doukai, Kou Takatori
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Patent number: 7633889Abstract: The present invention provides a carrier network in which a spanning tree with no loops can be constructed even in a dual homing configuration, and a communication method for a control frame. By allocating an identical virtual network identifier to a plurality of user networks connected to the carrier network, a single virtual network is constituted. An ingress communication node connected to a first user network of the plurality of user networks attaches a tag including the virtual network identifier to a control frame transmitted from the first user network, and transmits the control frame attached with the tag to a transmission destination determined on the basis of the virtual network identifier.Type: GrantFiled: February 17, 2005Date of Patent: December 15, 2009Assignee: Fujitsu LimitedInventors: Atsuko Higashitaniguchi, Hiroshi Kinoshita, Satsuki Norimatsu, Masami Doukai
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Patent number: 7590048Abstract: A label switching router (LSR) is disclosed in which a control label switched path (LSP) is set up on a route of LSRs, in the reverse direction of traffic, for restoration and protection. Link failure, node failure, etc., are signaled on the control LSP. Further, a process is carried out in units of LSPs (Bypass Tunnels), each of which bundles LSPs having the same switching point destination of traffic. A label is assigned to every Bypass Tunnel.Type: GrantFiled: October 17, 2003Date of Patent: September 15, 2009Assignee: Fujitsu LimitedInventor: Masami Doukai
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Publication number: 20070086333Abstract: 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.Type: ApplicationFiled: January 24, 2006Publication date: April 19, 2007Inventors: Masami Doukai, Ko Takatori, Kenichi Kawarai
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Patent number: 7120357Abstract: A WDM (Wavelength Divisional Multiplex) device is provided in which a client signal having a band that is greater than a band of a wavelength used for wavelength-division multiplexing is allocated a plurality of wavelengths and is transmitted as a wavelength-division multiplexed signal. The WDM device includes a used-band detecting part for detecting a used-band that is used by the client signal supplied from a client device. The used-band is detected from a path layer of the client signal using set-up information contained in the path layer of the client signal. The WDM device also includes a mapping part for mapping the detected used-band onto wavelengths used for wavelength-division multiplexing.Type: GrantFiled: October 2, 2002Date of Patent: October 10, 2006Assignee: Fujitsu LimitedInventor: Masami Doukai
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Publication number: 20060203735Abstract: A bridge apparatus, which enables communications to continue even if a fault or a disability of operation occurs, causing the spanning tree protocol to become inoperable and, furthermore, provides a network capable of keeping track of status changes thereof, are provided by a bridge apparatus constituting a network connected with other bridge apparatus, comprising an STP protocol processing unit for carrying out a spanning tree protocol; a port for transmitting and receiving a bridge protocol data unit with the other bridge apparatus; a fault detection unit for detecting a fault of the spanning tree protocol by monitoring the STP protocol processing unit; and a for-fault time BPDU transmission unit for transmitting a for-fault time bridge protocol data unit to the other bridge apparatus by way of the port if the fault detection unit detects a fault, or a disability of operation, of the spanning tree protocol.Type: ApplicationFiled: June 29, 2005Publication date: September 14, 2006Inventors: Kou Takatori, Yasushi Sasagawa, Masami Doukai
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Publication number: 20060198315Abstract: 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.Type: ApplicationFiled: June 30, 2005Publication date: September 7, 2006Inventors: Yasushi Sasagawa, Kenichi Kawarai, Masami Doukai, Kou Takatori
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Publication number: 20060182036Abstract: 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.Type: ApplicationFiled: June 20, 2005Publication date: August 17, 2006Inventors: Yasushi Sasagawa, Kenichi Kawarai, Masami Doukai, Kou Takatori
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Publication number: 20050163102Abstract: The present invention provides a carrier network in which a spanning tree with no loops can be constructed even in a dual homing configuration, and a communication method for a control frame. By allocating an identical virtual network identifier to a plurality of user networks connected to the carrier network, a single virtual network is constituted. An ingress communication node connected to a first user network of the plurality of user networks attaches a tag including the virtual network identifier to a control frame transmitted from the first user network, and transmits the control frame attached with the tag to a transmission destination determined on the basis of the virtual network identifier.Type: ApplicationFiled: February 17, 2005Publication date: July 28, 2005Inventors: Atsuko Higashitaniguchi, Hiroshi Kinoshita, Satsuki Norimatsu, Masami Doukai
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Publication number: 20040208502Abstract: A WDM (Wavelength Divisional Multiplex) device is provided in which a client signal having a band that is greater than a band of a wavelength used for wavelength-division multiplexing is allocated a plurality of wavelengths and is transmitted as a wavelength-division multiplexed signal. The WDM device includes a used-band detecting part for detecting a used-band that is used by the client signal supplied from a client device. The used-band is detected from a path layer of the client signal using set-up information contained in the path layer of the client signal. The WDM device also includes a mapping part for mapping the detected used-band onto wavelengths used for wavelength-division multiplexing.Type: ApplicationFiled: October 2, 2002Publication date: October 21, 2004Applicant: FUJITSU LIMITEDInventor: Masami Doukai
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Publication number: 20040179524Abstract: 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.Type: ApplicationFiled: March 30, 2004Publication date: September 16, 2004Inventors: Yasushi Sasagawa, Masami Doukai, Kou Takatori
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Publication number: 20040114595Abstract: A label switching router (LSR) is disclosed in which a control label switched path (LSP) is set up on a route of LSRs, in the reverse direction of traffic, for restoration and protection. Link failure, node failure, etc., are signaled on the control LSP. Further, a process is carried out in units of LSPs (Bypass Tunnels), each of which bundles LSPs having the same switching point destination of traffic. A label is assigned to every Bypass Tunnel.Type: ApplicationFiled: October 17, 2003Publication date: June 17, 2004Inventor: Masami Doukai