Fujitsu Corporation

Masaki Kubo

Masayuki Tanaka

Junichi Ishiwatari

Satoshi Nemoto

Nobuyuki Nemoto

Yuji Kamura

Hideo Sunaga

Shigeyuki Kobayashi

Shigeo Handa

Masaru Kameda

Shuji Sakakura

Shuniti Nakayama

A non-interruptive protection switching device which performs protection switching in a more efficient and robust way. The device has a working-channel signal storage unit to store data signals received through a working channel. Multiframe synchronization timings are detected by a working-channel multiframe synchronization controller, which provides a working-channel multiframe sync detection pulse signal when the main signals are in a normal condition and stops it when the channel is disrupted. A working-channel write controller controls every write access to the working-channel signal storage unit, generating a write pulse signal therefor. The working-channel write controller also produces working-channel write phase data by identifying a phase difference of the detected multiframe synchronization timing with respect to a reference phase signal. The generation of this write pulse signal is based on the multiframe sync detection pulse signal when the working-channel multiframe sync detection pulse signal is available, or on a free-running timebase when it is stopped. The stored data in the working- and protection-channel signal storage units are read out simultaneously, under the control of a read controller which produces read pulses from the write phase data.

Non-interruptive protection switching device and network system using the same

An alarm detection apparatus includes a plurality of alarm detectors detecting and/or cancelling alarms for identical and different error rates. The plurality of alarm detectors are grouped into a major detector unit made up of alarm detectors which detect major error rates, and a minor detector unit made up of alarm detectors which detect minor error rates. The major detector unit and the minor detector unit output detection outputs corresponding to specified detection rates thereof. A predetermined alarm detector corresponding to a part of the minor detector unit has a specified detection rate overlapping a specified detection rate of the major detector unit being controlled, so that a detection function or a detection output of the predetermined alarm detector is disabled.

Alarm detection apparatus

Growing community of inventors

Kanagawa, Japan

Masaki Kubo