Dynamic interlayer protection in optical telecommunication networks

• US 20050123294A1
• Filed: 10/14/2004
• Published: 06/09/2005
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Miriello, Virgilio, Mascolo, Vittorio
• Granted Patent: US 7,561,795 B2
• Time in Patent Office: Days
• US Class Current: 398/19
• CPC Class Codes: H04J 3/085 for ring networks, e.g. SDH/SONET rings, self-healing rings, meashed SDH/SONET networks
• CPC Class Codes: H04J 3/14 Monitoring arrangements for SDH/SONET rings H04J3/085

Abstract

The present invention relates to a method for protecting an optical telecommunication network against possible failures and signal degrades, the network comprising at least two nodes; working resources and protecting resources connecting the nodes; a first protection mechanism operating at a first protection layer; and a second protection mechanism operating at a second protection layer, characterized by a) the step, carried out by a node detecting a failure that could be managed by said first mechanism, of sending downstream an in-band Forward Protection Indication signalling in order to instruct the second protection mechanism not to operate, or b) the step, carried out by a node detecting a Bit Error Rate between a certain range, of sending downstream an in-band Link Degradation Indication signalling in order to instruct the second protection mechanism to operate.

Claims

1. A method for protecting an optical telecommunication network against possible failures and signal degrades, the network comprising at least two nodes;

working resources and protecting resources connecting the nodes;

a first protection mechanism operating at a first protection layer; and

a second protection mechanism operating at a second protection layer, characterized by

the step, carried out by a node detecting a failure that could be managed by said first mechanism, of sending downstream an in-band Forward Protection Indication signalling in order to instruct the second protection mechanism not to operate, and/or

the step, carried out by a node detecting a Bit Error Rate between a certain range, of sending downstream an in-band Link Degradation Indication signalling in order to instruct the second protection mechanism to operate.

2. The method according to claim 1, wherein said first protection layer is a OUT-trail section layer and said second protection layer is a ODU path layer.

3. The method according to claim 1, wherein said first protection mechanism comprises any of an OTU trail protection mechanism and an ODU-SPRing span switch.

4. The method according to claim 1, wherein said second protection mechanism comprises any of an ODU SNC or ODU-SPRing ring switch.

5. The method according to claim 1, wherein said Forward Protection Indication and Link Degradation Indication are coded signals sent into proper bits in the OverHead of ODU frame.

6. The method according to claim 5, wherein said proper bits comprise bits in path monitoring field.

7. The method according to claim 6, wherein said proper bits comprise at least one status bit.

8. The method according to claim 1, wherein the Bit Error Rate range activating the sending downstream of the Link Degradation Indication signalling is between about 1×

10<sup>−

2</sup> and 1×

10<sup>−

5</sup>.

9. The method according to claim 1, wherein the Bit Error Rate range activating the sending downstream of the Link Degradation Indication signalling is between about 1×

10<sup>−

3</sup> and 1×

10<sup>−

4</sup>.

19. A computer program comprising computer program means adapted to perform the method according to claim 1 when said program is run on a computer.

20. A computer readable medium having a program recorded thereon, said computer readable medium comprising computer program code means adapted to perform the method according to claim 1 when said program is run on a computer.

10. A network element for an optical telecommunication network comprising at least a further network element, working resources and protecting resources connecting the network elements;

a first protection mechanism operating at a first protection layer; and

a second protection mechanism operating at a second protection layer, characterized in that it comprises means

for sending downstream an in-band Forward Protection Indication signalling in order to instruct the second protection mechanism not to operate when a failure that could be managed by said first mechanism is detected; and

/or

for sending downstream an in-band Link Degradation Indication signalling in order to instruct the second protection mechanism to operate when a Bit Error Rate between a certain range is detected.

11. The network element according to claim 10, wherein said first protection layer is a OTU-trail section layer and said second protection layer is a ODU path layer.

12. The network element according to claim 10, wherein said first protection mechanism comprises any of an OTU trail protection mechanism and an ODU-SPRing span switch.

13. The network element according to claim 10, wherein said second protection mechanism comprises any of an ODU SNC or ODU-SPRing ring switch.

14. The network element according to claim 10, wherein said a device for sending downstream an in-band Forward Protection Indication signalling and said device for sending downstream an in-band Link Degradation Indication signalling comprise a device for writing proper bits in the OverHead of ODU frame.

15. The network element according to claim 14, wherein said device for writing proper bits in the OverHead of ODU frame comprises a device for writing at least one bit in path monitoring field, in particular at least one status bit.

16. A telecommunication network comprising at least two network elements according to claim 10.

17. An ODU frame for transmitting signals through an optical network, the network comprising at least two nodes;

working resources and protecting resources connecting the nodes;

a first protection mechanism operating at a first protection layer; and

a second protection mechanism operating at a second protection layer, the frame comprising an ODU overhead, an OPU overhead and an OPU payload, the ODU overhead comprising a path monitoring field which in turn comprises status bits, characterized in that

at least one bit of said status bits is written by a node detecting a failure that could be managed by said first mechanism for containing an in-band Forward Protection Indication signalling in order to instruct the second protection mechanism not to operate and/or

at least one bit of said status bits is written by a node detecting a Bit Error Rate between a certain range for containing an in-band Link Degradation Indication signalling in order to instruct the second protection mechanism to operate.

18. The ODU frame according to claim 17, wherein said Bit Error Rate range is preferably between about 1×

10<sup>−

2</sup> and 1×

10<sup>−

5</sup>, more preferably between about 1×

10<sup>−

3</sup> and 1×

10<sup>−

4</sup>.