Source: http://www.google.com/patents/US7389044?ie=ISO-8859-1
Timestamp: 2014-07-10 11:53:59
Document Index: 745038947

Matched Legal Cases: ['art 100', 'art 200', 'art 100', 'art 200', 'art 200', 'art 3']

Patent US7389044 - Method and system for providing a signature signal in an optical network in ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsAn optical network including multiple nodes is subject to intermittent faults that may raise alarms in the system. The invention focuses on an optical network based on the Any rate architecture. A single fault such as a client failure at a node in such a network can give rise to a loss of client signal...http://www.google.com/patents/US7389044?utm_source=gb-gplus-sharePatent US7389044 - Method and system for providing a signature signal in an optical network in the event of loss of a clientAdvanced Patent SearchPublication numberUS7389044 B2Publication typeGrantApplication numberUS 11/184,966Publication dateJun 17, 2008Filing dateJul 20, 2005Priority dateAug 11, 2004Fee statusPaidAlso published asCA2512710A1, US20060034608Publication number11184966, 184966, US 7389044 B2, US 7389044B2, US-B2-7389044, US7389044 B2, US7389044B2InventorsDavid Michael Ryan Holmes, Paul Mark ReepschlagerOriginal AssigneeAlcatel-Lucent Canada Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (6), Non-Patent Citations (1), Classifications (10), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetMethod and system for providing a signature signal in an optical network in the event of loss of a clientUS 7389044 B2Abstract An optical network including multiple nodes is subject to intermittent faults that may raise alarms in the system. The invention focuses on an optical network based on the Any rate architecture. A single fault such as a client failure at a node in such a network can give rise to a loss of client signal leading to multiple alarms detected at multiple points. To alleviate this problem this invention provides switching in a special Signature signal in place of the lost client signal. By detecting the Signature signal containing a specific code, the fault on the any rate-based architecture can be uniquely identified. In addition to fault identification, the Signature signal on the network makes it possible to maintain Clock and Data Recovery Locks at downstream nodes. The Signature signal serves also as a vehicle for carrying a special optical tag called Wavekey provided by the Wavelength Tracker technology developed by the Applicant. This optical tag includes a low frequency modulation of one or more dither tones onto an optical channel, which is uniquely identified by the tag. Maintaining the Wavekey is important for tracing the end-to-end path and power level of the signal on each wavelength. A method and a Field Programmable Gate Array-based system for the generation and identification of such a Signature signal that not only identifies the fault that has occurred on the optical network but also provides for the maintenance of the Wavekey, are described.
FIELD OF INVENTION The invention relates to optical communication systems, and in particular to a method and system for incorporating a specific Signature signal in an optical network when a client failure occurs, for reducing alarm propagation in an optical network.
BACKGROUND OF INVENTION An optical network consisting of multiple nodes is subject to intermittent faults that may raise alarms in the system. The invention focuses on an optical network based on the Any rate architecture. The need for an Any rate solution to seamlessly transport less common protocols within traditional telecommunication based metropolitan area network has been well established over the past decade by major carriers. On such an enclosed network that does not have any vendor mid-span meet within the network, it is possible to support a variety of native protocols. A single fault such as a client failure at a node in the network can, however, give rise to loss of client signal leading to multiple alarms detected at multiple points. A number of methods exist in the prior art for handling the loss of the client signal. One approach is to switch off the optical source. Although simple, such an approach leads to the loss of optical power and can give rise to a multitude of alarms as well as loss of Clock and Data Recovery (CDR) locks at downstream nodes in the network. Another approach is to maintain a �keep alive� signal, a fixed rate clock for example. Although optical power is maintained the CDR lock is lost and multiple alarms may be raised at downstream nodes. Examining all the raised alarms and determining the root cause alarm that leads to the solution of the actual problem that has occurred on the system is a difficult and time-consuming task. This in turn can significantly increase the time required for returning service to the network element.
SUMMARY OF THE INVENTION Therefore it is an objective of this invention to devise a method and system for generating a Signature signal when the client signal is lost due to a client failure.
BRIEF DESCRIPTION OF THE DRAWINGS Further features and advantages of the invention will be apparent from the following description of the embodiment, which is described by way of example only and with reference to the accompanying drawings in which:
DETAILED DESCRIPTION OF THE EMBODIMENT OF THE INVENTION Wavelength Tracker is a technology that traces the end-to-end path and power level of the signal on each wavelength and is developed by Tropic Network. A light path to be monitored on an optical network can be identified by using Wavelength Tracker. The Wavelength Tracker technology applies a unique optical tag to each wavelength (channel) at the Dense Wavelength Division Multiplexing (DWDM) layer. The unique optical tag includes a low frequency modulation of one or more dither tones onto the optical channel, which uniquely identify the optical channel. This optical tag (also called a Wavekey) is applied to the optical channel at the source node of the light path. The optical tag is detectable at intermediate nodes on the light path via inexpensive decoders present on line cards. Detection of the optical signature is accomplished without an Optical-Electrical-Optical (OEO) conversion at intermediate nodes, thus resulting in a cost-effective solution. Wavelength Tracker technology is used for a variety of applications including optical power monitoring and loss of light avoidance as well as for fault identification. The technology for generating and detecting Wavekeys has been described in U.S. patent application Ser. No. 09/963,501 by Obeda, P. D., et al, entitled �Topology Discovery in Optical WDM Networks�, filed on 27 Sep. 2001.
The technique used for achieving the objective of the invention is explained with the help of flowchart 100 and flowchart 200 presented in FIG. 1 b and FIG. 2 respectively. The operations at a node at which client failure occurs are explained with the help of flowchart 100 (see FIG. 1 b). Upon start (box 102) the procedure detects whether a fault (client failure) has occurred on the system (box 104). On the detection of a fault the procedure exits �Yes� from box 106 and selects the fault code corresponding to client failure to be transmitted (box 108). The Signature signal containing the fault code is then switched in (box 110) to replace the lost client. The procedure then starts the transmission of the Signature signal that is then through the network (box 111) and terminates (box 112). Once started the transmission of the Signature signal continues until the fault is corrected. If a fault did not occur the procedure exits �No� from box 106 and loops back to the input of box 104.
The operations performed at the receiver node that receives this transmitted signal are explained with the help of the flowchart 200 presented in FIG. 2. Upon start (box 202) the procedure receives the optical signal transmitted (box 203) and monitors this received signal (box 204). Pattern analysis to detect whether the Signature signal is present is performed next (box 206). If the Signature signal is detected the procedure exits �Yes� from box 206, raises the alarm corresponding to the fault code (client failure) (box 208) and terminates (box 210). If the Signature signal is absent, the procedure exits �No� from box 206 and loops back to the input of box 203. The procedure captured in the flowchart 200 is continuously invoked at the receiver node in an endless loop. Thus, box 202 is entered immediately after leaving box 210. Once raised the alarm remains active as long as the fault persists on the system.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS5654816 *Jun 6, 1996Aug 5, 1997Lucent Technologies Inc.Performance monitoring and fault location in optical transmissionUS5956165 *Sep 12, 1997Sep 21, 1999Mci Communications CorporationMethod and apparatus for updating subcarrier modulation in a communication networkUS6317231 *Sep 4, 1998Nov 13, 2001Lucent Technologies Inc.Optical monitoring apparatus and method for network provisioning and maintenanceUS7187862 *Mar 21, 2003Mar 6, 2007Eci Telecom Ltd.Method of locating faults in optical telecommunication networksUS20020135840 *Mar 23, 2001Sep 26, 2002Robert SpagnolettiConnection verification and monitoring in optical wavelength multiplexed communications systemsUS20040008988 *Sep 30, 2002Jan 15, 2004Gerstal Ornan A.Link discovery, verification, and failure isolation in an optical communication system* Cited by examinerNon-Patent CitationsReference1IEEE Standard 802,3, Mar. 8, 2002, Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications, pp. 40, 41, 118-121.Classifications U.S. Classification398/16, 398/31, 398/32, 398/33, 398/17International ClassificationH04B10/08Cooperative ClassificationH04L41/06, H04B10/00European ClassificationH04B10/00, H04L41/06Legal EventsDateCodeEventDescriptionSep 23, 2011FPAYFee paymentYear of fee payment: 4Sep 16, 2008CCCertificate of correctionMay 2, 2008ASAssignmentOwner name: 6467253 CANADA INC., CANADAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TROPIC NETWORKS INC.;REEL/FRAME:020894/0938Effective date: 20060105Owner name: ALCATEL-LUCENT CANADA INC., CANADAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TROPIC NETWORKS INC.;REEL/FRAME:020958/0112Effective date: 20070413Owner name: TROPIC NETWORKS INC., CANADAFree format text: CHANGE OF NAME;ASSIGNOR:6467253 CANADA INC.;REEL/FRAME:020958/0101Effective date: 20060106Jul 20, 2005ASAssignmentOwner name: TROPIC NETWORKS INC., CANADAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HOLMES, DAVID MICHAEL RYAN;REEPSCHLAGER, PAUL MARK;REEL/FRAME:016802/0110Effective date: 20050719RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google