Fujitsu Corporation

Eisaku Touma

Takashi Sakata

Akihisa Kawaguchi

Kazuhiro Minamimoto

A redundancy method in which a network is made redundant with a working path and a protection path. The method includes transmitting a working system supervising frame and a protection system supervising frame from a switch apparatus on transmission side to the working path and the protection path; passing, by a switch apparatus on reception side, the working system supervising frame received from the working path as well as abolishing the protection system supervising frame and passing the protection system supervising frame received from the protection path as well as abolishing the working system supervising frame; and performing a connectivity check for the working path and the protection path by using the passed working system supervising frame and the passed protection system supervising frame.

Redundancy method and switch apparatus

An optical signal judging system for judging an optical signal outputted from an optical switch the selectively outputs any one of input optical signals, comprises: a converting unit converting at least two optical signals branching off from an optical signal source into optical signals having wavelength bands differing from each other, and thus outputting the optical signals to said optical switch, wherein said optical switch outputs any one of at least the two optical signals so converted as to have the wavelength bands differing from each other, which have been inputted from said converting unit.

Optical signal judging system and optical signal judging method

A method of controlling an optical wavelength division multiplexing transmission apparatus achieves stable wavelength division multiplexing optical transmission by switching a control mode of an optical amplification section in accordance with an input state of optical signals of various wavelengths. Accordingly, the method involves, upon startup of the optical wavelength division multiplexing transmission apparatus, initial setting of information such as the wavelengths being used and the number of wavelengths being used, setting the amount of optical attenuation for each wavelength to a maximum value, and setting an optical amplification unit to ALC. Then, upon input of an optical signal corresponding to the wavelengths being used, the amount of optical attenuation corresponding to the input optical wavelength is controlled so that the levels of the input optical signals analyzed by the spectral analysis unit are approximately constant; and moreover, so that the input optical level per single wavelength input into the optical amplification unit is of a level which corresponds with the number of wavelengths being used. Then the apparatus shifts to normal operating conditions. Next, when the number of wavelengths being input varies, the optical amplifier is switched to AGC, and after the power level of the optical signal of each wavelength is adjusted, the optical amplifier is switched to ALC again.

Method of controlling optical wavelength division multiplexing transmission apparatus

The present invention provides an optical wavelength multiplexing transmission apparatus and an optical output control method for an optical wavelength multiplexing transmission apparatus in an optical wavelength multiplexing transmission system using a main signal light and an OSC light. The optical wavelength multiplexing transmission apparatus () is made up of a first transmitting/receiving section () a second transmitting/receiving section () and an apparatus supervisory control unit (). This can not only achieve quick restoration from troubles, but also stably calculate an optical output level even if a change of the number of wavelengths to be multiplexed takes place in a main signal light, and even save troublesome adjustments for the improvement of reliability of a transmission line while eliminating the need for a signal source for the adjustment of a receive optical level at the initial installation.

Optical wavelength multiplexing transmission apparatus and optical output control method for optical wavelength multiplexing transmission apparatus

The present invention provides an optical wavelength multiplexing transmission apparatus and an optical output control method for an optical wavelength multiplexing transmission apparatus in an optical wavelength multiplexing transmission system using a main signal light and an OSC light. The optical wavelength multiplexing transmission apparatus ( ) is made up of a first transmitting/receiving section ( ), a second transmitting/receiving section ( ) and an apparatus supervisory control unit ( ). This can not only achieve quick restoration from troubles, but also stably calculate an optical output level even if a change of the number of wavelengths to be multiplexed takes place in a main signal light, and even save troublesome adjustments for the improvement of reliability of a transmission line while eliminating the need for a signal source for the adjustment of a receive optical level at the initial installation.

In an optical subscriber network system which connects plural optical network units to an optical service unit using passive optical elements through an optical transmission line, the optical transmission line is duplexed with a lower cost. The optical service unit and the optical network units each have plural transmission-reception portions the wavelengths of which are different from each other, and the inputs and outputs of the plural transmission-reception portions are multiplexed with the wavelengths (WDM) into a single optical transmission line to form a pseudo redundant communication path between the optical service unit and the optical network units. The communication which uses a certain wavelength between the optical service unit and the optical network units is active, and the communication which uses another wavelength is a standby. When the active communication has a fault, a switchover operation to the standby communication is performed. The communication path using plural wavelengths between the optical service unit and the optical network units can select either the function of &ldquo;with redundancy&rdquo; or &ldquo;without redundancy&rdquo; or &ldquo;enhanced line speed&rdquo;, depending on subscribers' demands.

Optical subscriber network system

The invention provides an optical subscriber network system which can secure dual construction of optical transmission/reception sections of optical network units, specification of a failed faulty point in optical transmission lines and reception circuits of the optical network units and regular timing transmission of upstream data. The optical subscriber network system has a passive optical network construction wherein a plurality of network units are accommodated in a station apparatus through an optical transmission line using a passive optical element, and includes bypass transmission lines for mutual supervision control between the network units. A network unit mutual supervision control signal is communicated between the network units through the bypass transmission lines. The network unit mutual supervision control information received by each of the network units is transmitted to the station apparatus through the optical transmission line so that a fault is supervised based on the network unit mutual supervision control information by the station apparatus.

Optical subscriber network system and fault supervising method for optical subscriber network system

In a passive optical network in which a plurality of subscriber equipments are connected to central office equipment via a star coupler, non-faulty subscriber equipments are quickly recovered from a communication failure caused by a faulty subscriber equipment. A control signal of wavelength .lambda..sub.2 is wavelength-division multiplexed with a main signal of wavelength .lambda..sub.1. Using the control signal of wavelength .lambda..sub.2, the subscriber equipments are selectively deactivated from the central office equipment, and based on the recovery state during the deactivation process, the faulty subscriber equipment is located and only the faulty subscriber equipment is deactivated.

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Kawasaki, Japan

Eisaku Touma