Abstract: A recovery of a secondary DB is executed by a log including a update difference of a primary DB, and a command is executed by adding the command to the log and analyzing the log by a secondary site. An operation command execution in the secondary site is applied to the DB having the consistency in the transaction at the same timing as a primary site or an intended timing, by transferring and executing the operation command via the log. In the case that the command is constituted by a snap shot generating instruction, a plurality of volumes of a mirror set forming a secondary storage apparatus are set to a pair state and the secondary DB is written in each of the volumes and synchronized, and the mirror set is set to a split state after the synchronization is finished, whereby a secondary DB is stored.

Abstract: Disclosed here is a communication apparatus and method for inter-AS routing, which enables policy routing between a stub AS and an upstream AS. The policy routing includes control which is applicable only between adjacent autonomous systems (AS's). When a subject communication apparatus notifies its own AS number or advertises attribute information that includes its own AS number to a stub AS, the communication apparatus does not use its own AS number or uses the AS number of the upstream autonomous system (AS) instead of its own AS number. In addition, when relaying routing information received from one AS to another, the subject communication apparatus also relays attribute information without discarding the information, although the information is conventionally not relayed to itself.

Abstract: In a WDM type PON system, each ONU comprises an optical transmitter capable to transmit optical signals with variable wavelengths, an optical signal receiving filter variable its receiving wavelength, and a control unit. An OLT selects in response to a wavelength allocation request from each ONU, a transmitting wavelength and a receiving wavelength out of currently free wavelengths and allocates these wavelengths to the requester ONT. The control unit of the ONU switches the transmitting wavelength of the optical transmitter and the receiving wavelength of the optical signal receiving filter to the wavelengths specified in a response message from the OLT and starts data communication.

Abstract: An optical transmission apparatus includes a demultiplexer for separating wavelength-division multiplexing light received from a first optical transmission line into signals of different wavelengths to transmit the signals to an outside and a multiplexer for multiplexing signals of different wavelengths received from the outside to transmit multiplexed signals to a second optical transmission line. An input check unit is provided for monitoring a power level of a signal separated by the demultiplexer and for providing an output indicative thereof. An output adjuster is provided for intercepting a signal from the outside so as to inhibit receipt of the signal from the outside by the multiplexer depending on the output of the input check unit.

Abstract: An optical transmission apparatus includes optical transmitters for transmitting optical signals and first monitor units for monitoring optical signals from the optical transmitters. A multiplexer is provided for multiplexing the optical signals from the optical transmitters into a multiplexed signal. A second monitor unit is provided for monitoring each optical signal which is multiplexed in the multiplexed signal from the multiplexer. A processing unit is provided for comparing a first number of optical signals detected by the first monitor units and a second number of optical signals detected by the second monitor unit.

Abstract: Interlayer-coordinated communication-line switching in a network including two layers, each having a switching function. In the present invention, a communication apparatus which (1) is connected with a network including (i) lower layer apparatus which are connected with communication lines of a lower layer and communication lines of an upper layer and conducts line switching in the lower layer and (ii) upper layer apparatuses which are connected with the communication lines of the upper layer and have means for line switching in the upper layer and (2) detects line failure and coordinates line switching using failure information on the lower and upper layer communication lines.

Abstract: A transmission system comprising a relaying apparatus and concentrated subscriber line transmission apparatuses, the relaying apparatus including a first buffer memory for buffering a control request to be transmitted to one of the concentrated subscriber line transmission apparatuses, a second buffer memory for buffering data to be downloaded to specific one of the concentrated subscriber line transmission apparatuses, and a control unit for generating maintenance frames each including a control request, and download frames each including download data, and transmitting these frames to one of the concentrated subscriber line transmission apparatuses, selectively. The control unit controls the transmission of download frames, depending on status of traffic of frames being relayed from the communication network toward one of the concentrated subscriber line transmission apparatuses and on whether a control request awaiting transmission is buffered.

Abstract: Optical transmission equipment, capable of electrically adjusting the delay difference between a plurality of digital signal paths to be connected to a multilevel optical modulation unit or demodulation unit, having multiplexing circuits connected to the digital signal paths and a delay adjustment unit inserted in one of the digital signal paths to adjust delay of N-bit-parallel low-speed digital signals with the timing unit of a bit period of a high-speed serial digital signal to be outputted from multiplexing circuit.

Abstract: An optical transmission apparatus comprising a first detector for detecting the power of the supervisory signal light separated from received wavelength-division multiplexed signal lights; a second detector for detecting the power of the wavelength-division multiplexed signal lights after the separation of the supervisory signal light; a gain-controlled type optical amplifier for amplifying the wavelength-division multiplexed signal lights; an optical attenuator coupled to the amplifier; and a control unit for controlling the optical amplifier and the optical attenuator so as to keep the output level of the wavelength-division multiplexed signal lights to a predetermined target value, wherein the control unit restrains automatic output level control by the optical attenuator when the supervisory signal light power fluctuates within its permissible range and fluctuations in the signal light power have deviated from its permissible range.

Abstract: A station-side communication device connected to subscriber-side communication devices via an optical combining device; sending, to the subscriber-side communication devices, a distance measurement request signal; computing transmission delay times of optical signals from the individual subscriber-side communication devices by receiving distance measurement signals, and including: a threshold control part identifying the level of distance measurement signals; a signal detection part detecting breaks in the distance measurement signals from the threshold control part; a transmission granting part determining the timing at which transmission of optical signals is granted, and a reset timing generation part that, there is notification of detection of a break in the distance measurement signal from the signal detection part while it is being notified that distance measurement is carried out to and from the subscriber-side communication devices from the transmission granting part, sends a reset signal indicating t

Abstract: In a WDM type PON system, each ONU comprises an optical transmitter capable to transmit optical signals with variable wavelengths, an optical signal receiving filter variable its receiving wavelength, and a control unit. An OLT selects in response to a wavelength allocation request from each ONU, a transmitting wavelength and a receiving wavelength out of currently free wavelengths and allocates these wavelengths to the requester ONT. The control unit of the ONU switches the transmitting wavelength of the optical transmitter and the receiving wavelength of the optical signal receiving filter to the wavelengths specified in a response message from the OLT and starts data communication.

Abstract: In a WDM type PON system, each ONU comprises an optical transmitter capable to transmit optical signals with variable wavelengths, an optical signal receiving filter variable its receiving wavelength, and a control unit. An OLT selects in response to a wavelength allocation request from each ONU, a transmitting wavelength and a receiving wavelength out of currently free wavelengths and allocates these wavelengths to the requester ONT. The control unit of the ONU switches the transmitting wavelength of the optical transmitter and the receiving wavelength of the optical signal receiving filter to the wavelengths specified in a response message from the OLT and starts data communication.

Abstract: A station-side communication device connected to subscriber-side communication devices via an optical combining device; sending, to the subscriber-side communication devices, a distance measurement request signal; computing transmission delay times of optical signals from the individual subscriber-side communication devices by receiving distance measurement signals, and including: a threshold control part identifying the level of distance measurement signals; a signal detection part detecting breaks in the distance measurement signals from the threshold control part; a transmission granting part determining the timing at which transmission of optical signals is granted, and a reset timing generation part that, there is notification of detection of a break in the distance measurement signal from the signal detection part while it is being notified that distance measurement is carried out to and from the subscriber-side communication devices from the transmission granting part, sends a reset signal indicating t

Abstract: A station-side communication device connected to subscriber-side communication devices via an optical combining device; sending, to the subscriber-side communication devices, a distance measurement request signal; computing transmission delay times of optical signals from the individual subscriber-side communication devices by receiving distance measurement signals, and including: a threshold control part identifying the level of distance measurement signals; a signal detection part detecting breaks in the distance measurement signals from the threshold control part; a transmission granting part determining the timing at which transmission of optical signals is granted, and a reset timing generation part that, there is notification of detection of a break in the distance measurement signal from the signal detection part while it is being notified that distance measurement is carried out to and from the subscriber-side communication devices from the transmission granting part, sends a reset signal indicating t

Abstract: A neighbor sector is automatically set to effectively perform soft handover. A base station corresponding to a first sector to communicate with a wireless terminal and a base station corresponding to a second sector to start communication with the wireless terminal due to movement of the wireless terminal or the like transmit a terminal identifier acquired from the wireless terminal, a time and a sector identifier to a base station control part (control part in the following). The control part successively stores the received sector identifier into a table correspondingly to the terminal identifier and the time received from the base station. Besides, the control part refers to the table, judges whether different sector identifiers are stored in a previously determined time range, regards a pair of the two different sector identifiers as neighbor sector candidates and counts the number of times they are regarded as the neighbor sector candidates.

Abstract: Since, in Mobile IP, the correspondence of one Mobile Node home address and a care-of address is assumed to be one to one, it is not possible to associate multiple care-of addresses with one home addresses, select an appropriate care-of address from among these and dynamically modify the forwarding destination. In the invention, the binding update sent by the Mobile Node to the Home Agent is extended in order to make it possible to also report the application ID at the same time. The Home Agent selects an appropriate care-of address, based on the application ID.

Abstract: In a PON system, a PON-ID assigned to a connected ONU before replacement is assigned to a newly connected ONU after the replacement and, setting data before the replacement is succeeded also after the replacement. An OLT includes a PON-ID state where a management state of the PON-ID is stored, a PON-ID management table where the PON-ID and an ONU serial number of the connected ONU and setting data are correspondingly stored and, a delete ONU table where the PON-ID and an ONU serial number of a replacement object are correspondingly stored. When the OLT receives an ONU replacement instruction from an operation system, the PON-ID assigned to the ONU of the replacement object is assigned to an ONU newly connected during the ONU replacement.

Abstract: In a PON system, a PON-ID assigned to a connected ONU before replacement is assigned to a newly connected ONU after the replacement and, setting data before the replacement is succeeded also after the replacement. An OLT includes a PON-ID state where a management state of the PON-ID is stored, a PON-ID management table where the PON-ID and an ONU serial number of the connected ONU and setting data are correspondingly stored and, a delete ONU table where the PON-ID and an ONU serial number of a replacement object are correspondingly stored. When the OLT receives an ONU replacement instruction from an operation system, the PON-ID assigned to the ONU of the replacement object is assigned to an ONU newly connected during the ONU replacement.

Abstract: In a PON system, a PON-ID assigned to a connected ONU before replacement is assigned to a newly connected ONU after the replacement and, setting data before the replacement is succeeded also after the replacement. An OLT includes a PON-ID state where a management state of the PON-ID is stored, a PON-ID management table where the PON-ID and an ONU serial number of the connected ONU and setting data are correspondingly stored and, a delete ONU table where the PON-ID and an ONU serial number of a replacement object are correspondingly stored. When the OLT receives an ONU replacement instruction from an operation system, the PON-ID assigned to the ONU of the replacement object is assigned to an ONU newly connected during the ONU replacement.