The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 02, 1999
Filed:
Dec. 24, 1996
Ornan Alexander Gerstel, Riverdale, NY (US);
Chung-Sheng Li, Ossining, NY (US);
Rajiv Ramaswami, Ossining, NY (US);
Chaoyu Yue, North Tarrytown, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A fault detecting apparatus and method for a network node of an optical transmission system receives a wavelength division multiplexed (WDM) optical signal which includes a group of optical channels. The network node includes an optical demultiplexer, optical switch, optical multiplexer, and an optical channel add/drop device. Supervisory optical signals having a different wavelength than the wavelengths of the group of optical channels are generated and spliced with each optical channel by the optical demultiplexer. The supervisory channel optical power is tapped off at various points in the network node, such as the output optical channels of the demultiplexer, dropped optical channel outputs, output optical channels from the optical switch, and the output WDM optical signal of the multiplexer. The supervisory channels are monitored by a wavemeter for bypass lightpaths and dropped lightpaths. Added optical channels are monitored by monitoring a portion of the signal power in the added lightpath of the added optical channel. If the wavemeter detects the absence of the supervisory signal, or the portion of the added optical channel, this indicates a fault condition and the network control is notified to effect correction of the fault.