Optical ring network with hub node and method

• US 20040208578A1
• Filed: 10/01/2002
• Published: 10/21/2004
• Est. Priority Date: 05/29/2002
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Takeguchi, Koji, Kinoshita, Susumu, Gumaste, Ashwin Anil
• Granted Patent: US 7,184,663 B2
• Time in Patent Office: Days
• US Class Current: 398/83
• CPC Class Codes: H04J 14/021 Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0294 Dedicated protection at the optical channel (1+1)
• CPC Class Codes: H04J 14/0297 Optical equipment protection
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0015 using splitting combining
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0024 using space switching
• CPC Class Codes: H04Q 2011/0092 Ring

Abstract

An optical network includes an optical ring and a plurality of add/drop nodes coupled to the optical ring. Each of the add/drop nodes is operable to passively add and drop one or more traffic streams to and from the optical ring, and each traffic stream comprises a channel. A hub node also coupled to the optical ring is operable to selectively pass and terminate individual traffic streams.

Claims

1. An optical network, comprising:

an optical ring;

a plurality of add/drop nodes coupled to the optical ring;

each of the add/drop nodes operable to passively add and drop one or more traffic streams to and from the optical ring, each traffic stream comprising a channel; and

a hub node coupled to the optical ring and operable to selectively pass and terminate individual traffic streams.

2. The optical network of claim 1, wherein each optical ring is open at least one point for each channel.

3. The optical network of claim 1, wherein the hub node comprises a demultiplexer to demultiplex an ingress signal into sets of channels, each constituting one or more constituent channels, a switch element to selectively pass through or terminate the constituent channels, and a multiplexer to combine the pass through constituent channels into an egress signal

4. The optical network of claim 3, the hub node further operable to, during normal operations, terminate a majority of traffic streams and pass through the remaining traffic streams.

5. The optical network of claim 3, wherein the demultiplexer and the multiplexer comprise array waveguides.

6. A hub node for a bidirectional passive optical ring, the hub node operable to open the ring in each direction for each of a plurality of traffic streams during normal operations, each traffic stream comprising a channel, and to selectively close the ring for individual channels for protection switching of interrupted traffic streams in response to a fault.

7. The hub node of claim 6, further comprising a demultiplexer to demultiplex an ingress signal into sets of channels, each constituting one or more constituent channels, a switch element to selectively pass through or terminate the constituent channels, and a multiplexer to combine the pass through constituent channels into an egress signal.

8. The hub node of claim 7, further operable to, during normal operations, terminate a majority of traffic streams and pass through the remaining traffic streams.

9. The optical network of claim 7, wherein the demultiplexer and the multiplexer comprise array waveguides.

10. A method of protection switching traffic carried on an optical ring network, the ring network comprising a plurality of add/drop nodes and a hub node, the method comprising:

detecting an interruption in a working path of traffic carried on the optical ring network, the working path extending between an origination node and a destination node, the interruption preventing the traffic from reaching the destination node from the origination node via the working path;

terminating along a protection path terminable signals of the wavelength of the traffic, the protection path comprising the hub node and extending between the origination node and the destination node;

reconfiguring the hub node so as to pass through the traffic; and

without changing the wavelength of the traffic, forwarding the traffic along the protection path and through the hub node to the destination node.

11. The method of claim 10, further comprising isolating the interruption.

12. The method of claim 11, wherein isolating the interruption comprises:

opening the first optical ring at a first node adjacent in a first direction to the interruption; and

opening the second optical ring at a second node adjacent in a second direction to the interruption.

13. The method of claim 11, further comprising reverting the network to a pre-interruption state in response to at least a repair of the interruption.

14. An optical network, comprising:

an optical ring;

a plurality of add/drop nodes coupled to the optical ring;

a hub node coupled to the optical ring;

means for detecting an interruption in a working path of traffic carried on the optical ring network, the working path extending between an origination node and a destination node, the interruption preventing the traffic from reaching the destination node from the origination node via the working path;

means for terminating along a protection path terminable signals of the wavelength of the traffic, the protection path comprising the hub node and extending between the origination node and the destination node;

means for reconfiguring the hub node so as to pass through the traffic; and

means for without changing the wavelength of the traffic, forwarding the traffic along the protection path and through the hub node to the destination node.

15. The optical ring network of claim 14, wherein each of the plurality of add/drop nodes comprises means to passively add and drop traffic from the optical ring.

16. The optical network of claim 14, further comprising means for isolating the interruption.

17. The optical network of claim 14, wherein the means for isolating the interruption comprises:

means for opening the first optical ring at a first node adjacent in a first direction to the interruption; and

means for opening the second optical ring at a second node adjacent in a second direction to the interruption.

18. The optical network of claim 14, further comprising means for reverting the network to a pre-interruption state in response to at least a repair of the interruption.

19. A method for transporting optical signals on an optical network, the optical network comprising a bidirectional optical ring, a plurality of add/drop nodes, and a hub node, the method comprising:

passively adding and dropping a plurality of traffic streams to and from the optical ring, each traffic stream comprising a channel;

at the hub node, opening the ring in each direction for each of the traffic streams during normal operations; and

at the hub node, selectively closing the ring for individual channels for protection switching of interrupted traffic streams in response to a fault.

20. The method of claim 19, further comprising:

at the hub node, demultiplexing at the hub node an ingress signal from the optical ring into sets of channels, each constituting one or more constituent channels

at the hub node, selectively passing through or terminating the constituent channels;

at the hub node, multiplexing the pass through constituent channels into an egress signal; and

outputting the egress signal from the hub node to the optical ring.

21. The method of claim 19, further comprising, during normal operations, terminating a majority of traffic streams and passing through through the remaining traffic streams.