Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Patent
1997-06-11
2000-08-01
Chan, Jason
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
359119, 359110, 359128, H04B 1020, H04B 1008, H04J 1402
Patent
active
060975164
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method or a system for a Self-Healing Node architecture in a fiber ring network, and more particularly to an optical add drop multiplexer (OADM).
BACKGROUND
A fiber ring network is a collection of nodes forming a closed loop, where each node is connected via a duplex communications facility. The multiplexing devices used in the SDH/SONET ring architecture are Add Drop Multiplexers (ADM) that add and drop local channels and pass through transit channels. A Self-Healing Ring is a ring network that provides redundant bandwidth so that disrupted services can automatically be restored following network failures.
Present technology, as disclosed in U.S. Pat. No. 5,185,736 to Tyrrel et al. can only provide protection against fiber failure, not node failure. In U.S. Pat. No. 4,704,713 to Haller et al. is shown a method for dealing with the node failure, but no fiber failure. Additionally, this solution is not transparent to services, bit rate and code format, due to the electro-optical conversion in every second node.
Wavelength Division Multiplexing has so far been focusing on packet switched networks as disclosed in U.S. Pat. No. 4,979,879 to Habbab et al.; U.S. Pat. No. 4,797,879 to Eda; U.S. Pat. No. 5,208,692 to McMahon. All of these solutions are for Local Area Networks (LAN), and are not competitors to SDH/SONET systems.
A SDH/SONET ring is costly to upgrade. If changes are made in one subnode, e.g., increasing the bit rate, changes have to be made in all the other subnodes around the ring as well. However, with the introduction of a multi-wavelength based network layer the flexibility can be extended even more. New transmission formats can be introduced on different wavelengths and in the same fiber network, e.g., a physical ring.
When the total traffic flow concentrates in the same fiber, the demand for protection of the ring increases. A desirable protection feature is a simple, fast and efficient handling whenever a fault occurs.
SUMMARY
According to a first object of the present invention is disclosed a method of configuring subnodes, or configuring a system of subnodes, in an optical network ring against both node and fiber failure, which network comprises a working ring and a stand-by ring and each subnode includes monitor points, selective optical filter means, optical 2.times.2 switch means and optical amplifier means, and further comprising the steps of monitoring the inputs and outputs of each subnode for the working and stand-by rings by means of monitor device means monitoring the monitor points; generating by means of the monitor device means an alarm signal upon detection of signal loss at a subnode; setting as a response to the alarm signal the state of the subnode causing the alarm signal from a first state into one of a number of possible conditions as a function of the generated alarm signal; and selecting a switch configuration for the subnode according to the new state.
Further objects and steps of the method and the system according to the present invention are set forth in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention, together with further objects and advantages thereof, may best be understood by making a reference to the following detailed description taken together with the accompanying drawings, in which:
FIG. 1 is a simple block diagram illustration of an optical Self-Healing Ring according to the invention;
FIG. 2 is a block diagram of an Optical Add Drop Multiplexor utilized in the present invention;
FIG. 3 is a table representation of node state, switch configuration and monitor signals corresponding to the OADM of FIG. 2;
FIG. 4 demonstrates the course of events in a symbolic way when folding two nodes assigned Node 2 and Node 1;
FIG. 5 demonstrates in a similar way the scheme for line switching of three nodes assigned Node 2, Node 3 and Node 4;
FIG. 6 is a flow chart demonstrating folding of an WDM Self-Healing Ring; and
FIG. 7 is a flow chart demonstrating line switching of a WDM Self-Heali
REFERENCES:
patent: 3652798 (1972-03-01), McNeilly et al.
patent: 4190821 (1980-02-01), Woodward
patent: 4704713 (1987-11-01), Haller et al.
patent: 4797879 (1989-01-01), Habbab et al.
patent: 4829512 (1989-05-01), Nakai et al.
patent: 4979879 (1990-12-01), Da Costa
patent: 5003531 (1991-03-01), Farinholt et al.
patent: 5185736 (1993-02-01), Tyrrell et al.
patent: 5208692 (1993-05-01), McMahon
patent: 5229875 (1993-07-01), Glista
patent: 5278824 (1994-01-01), Kremer
patent: 5335104 (1994-08-01), Johnson
patent: 5442623 (1995-08-01), Wu
patent: 5450224 (1995-09-01), Johansson
patent: 5680235 (1997-10-01), Johansson
patent: 5710777 (1998-01-01), Gawne
Chan Jason
Sedighian Mohammad
Telefonaktiebolaget LM Ericsson
LandOfFree
Optical add drop multiplex (OADM) does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical add drop multiplex (OADM), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical add drop multiplex (OADM) will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-669508