Fujitsu Corporation

Kazuhiro Minamimoto

Akihisa Kawaguchi

Takashi Fukagawa

Eisaku Touma

Masanori Kondo

Yasushi Nishine

Toshihiro Ban

Jun-ichi Shimada

According to an aspect of an embodiment, a node apparatus used in at least part of nodes in a network formed by a plurality of nodes coupled in the shape of a ring, comprising: a working node function performing unit for performing functions as a working apparatus that selectively drops a frame destined for a terminal hosted by the node itself among frames transmitted on the ring and adds a frame from the terminal hosted by the node itself to frames transmitted on the ring; a back-up function performing unit for performing functions as a back-up apparatus that lets a frame destined for a terminal hosted by the node itself pass through to an adjacent node and discards a frame from the terminal hosted by the node itself; and a function selection unit for selectively enabling one of the working node function performing unit and the back-up function performing unit.

Ring node apparatus

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

A WDM transmission device includes a level adjustment unit adjusting levels of optical signals having different wavelengths, a multiplexer multiplexing the optical signals, an amplifier amplifying a multiplexed optical signal, and a monitor unit monitoring the multiplexed optical signal applied to the amplifier and a level of an output signal of the amplifier and controlling the level adjustment unit so that the levels of the optical signals fall within a predetermined level range in which the amplifier can operate normally.

Level adjustment method and wavelength division multiplexing device and system

A method for detecting an erroneous IF board mounting in a transmission device which can be employed even when one-to-one correspondence is not established for slots on a transmission device and normally mounted IF boards determines when the transmission device is activated, for each of transmission channel interfaces, whether or not a plurality of types of packages having different transmission speeds are mounted. When a plurality of types of packages having different transmission speeds coexist at one of the transmission channel interfaces, it is concluded that all the packages in the transmission channel interface are erroneously mounted.

Growing community of inventors

Kawasaki, Japan

Kazuhiro Minamimoto