Fault recovery system and method for a communications network

• US 20030145246A1
• Filed: 12/20/2002
• Published: 07/31/2003
• Est. Priority Date: 10/31/2001
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Suemura, Yoshihiko
• Granted Patent: US 7,471,625 B2
• Time in Patent Office: Days
• US Class Current: 714/2
• CPC Class Codes: H04J 2203/0053 Routing
• CPC Class Codes: H04J 2203/006 Fault tolerance and recovery
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/62 Wavelength based optical switching H04Q11/0062

Abstract

A source node of a network transmits a path setup message for requesting a traffic path to a destination node. First and second nodes, located between the source and destination nodes, establishes first and second parallel transport paths on a first fault recovery layer between them. The first node further includes a database for storing identities of the first and second paths as a single virtual link as viewed from the source node. The first node responds to the path setup message for accommodating the traffic path on a second fault recovery layer through the first transport path. Each node accommodates the traffic path through the second transport path when the first transport path fails. The first node advertises recovery type of the virtual link as equal to the recovery type of the first and second transport paths, and/or equal to most unreliable recovery type of its component links.

Claims

1. A communications network comprising:

first and second nodes interconnected by communication links; and

a traffic path established between a source node and a destination node;

each of said first and second nodes including routing control means for establishing first and second transport paths on a first fault recovery layer between said first and second nodes,

said first node further including a database for storing identities of said first and second transport paths as a single virtual link as viewed from said source node, said first node advertising fault recovery type of said virtual link as being equal to fault recovery type of said first and second transport paths,

said first and second nodes accommodating said traffic path on a second fault recovery layer through said first transport path, and accommodating said traffic path on said second fault recovery layer through said second transport path when said first transport path is not working properly.

4. The communications network of claim 1 or 2, wherein said first and second fault recovery layers are hierarchically structured in such a relationship that no contention occurs between the first and second fault recovery layers when a failure occurs in said first and second transport paths.

5. The communications network of claim 1 or 2, wherein said first node is an initiation node of said traffic path and said second node is a termination node of said traffic path.

6. The communications network of claim 1 or 2, wherein said first and second transport paths do not share a common physical link.

7. The communications network of claim 6, wherein said first and second transport paths do not pass through a common node other than said first and second nodes.

8. The communications network of claim 1 or 2, wherein said second node is downstream of said first transport path and monitors said first transport path for detecting a failure.

9. The communications network of claim 1 or 2, wherein said first node supplies a signal on said traffic path to said first and second transport paths simultaneously and wherein said second node receives said signal from said first transport path when the first transport path is working properly and receives said signal from said second transport path when the first transport path is not working properly.

10. The communications network of claim 1 or 2, wherein said first node supplies a signal on said traffic path to said first transport path and said second node receives said signal from said first path when the first transport path is working properly, and wherein said first node supplies said signal to said second transport path and said second node receives said signal from said second transport path when said first transport path is not working properly.

11. The communications network of claim 1 or 2, wherein said first node supplies a signal on said traffic path to said first transport path and said second node receives said signal from said first transport path when the first transport path is working properly, and wherein said first node supplies said signal to said first and second transport paths simultaneously and said second node receives said signal from said second transport path when said first transport path is not working properly.

12. The communications network of claim 1 or 2, wherein each of said first and second transport paths is established on an unprotected transmission medium.

13. The communications network of claim 1 or 2, wherein each of said first and second nodes comprises:

a first table memory for storing routing data of said first and second transport paths and said traffic path;

a second table memory for storing switching data derived from said routing data;

a switch for terminating said first and second transport paths; and

a controller for establishing a connection in said switch according to said switching data so that said traffic path is accommodated in said first transport path,

said controller responding to an occurrence of a failure in said first transport path for updating said routing data, updating the switching data according to the updated routing data and reestablishing a connection in said switch according to the updated switching data so that said traffic path is accommodated in said second transport path.

14. The communications network of claim 13, wherein said controller derives said switching data from said routing data by translation from a control plane of said network to a transport plane of said network.

15. The communications network of claim 14, wherein said control plane is a GMPLS (generalized multi-protocol label switching) system and said transport plane is an SDH/SONET system.

16. The communications network of claim 14, wherein said controller updates said routing data when said failure is detected in said first transport path, updates said switching data according to the updated routing data and reestablishes said connection according to the updated switching data.

17. The communications network of claim 1 or 2, wherein each of said first and second transport paths has a bandwidth resource greater than a bandwidth resource of said traffic path.

18. The communications network of claim 1 or 2, wherein each of said first and second transport paths is a wavelength path.

2. A communications network comprising:

first and second nodes interconnected by communication links; and

a traffic path established between a source node and a destination node;

each of said first and second nodes including routing control means for establishing first and second transport paths on a first fault recovery layer between said first and second nodes,

said first node further including a database for storing identities of said first and second transport paths as a single virtual link as viewed from said source node, said virtual link comprising a series of component links, said first node advertising fault recovery type of said virtual link as being equal to most unreliable fault recovery type of said component links,

said first and second nodes accommodating said traffic path on a second fault recovery layer through said first transport path, and accommodating said traffic path on said second fault recovery layer through said second transport path when said first transport path is not working properly.

3. The communications network of claim 2, wherein said first node advertises fault recovery type of said virtual link as being equal to fault recovery type of said first and second transport paths.

19. A multi-domain communications network comprising:

a plurality of network domains interconnected by inter-domain links, each of said network domains including first and second nodes interconnected by inter-node links; and

a traffic path established between a source node and a destination node,

the first node, of each of said domains establishing first and second parallel transport paths on a first fault recovery layer to the second node of the domain and including a database for storing identities of said first and second parallel transport paths as a single virtual link as viewed from said source node, and accommodating said traffic path on a second fault recovery layer through the first transport path of the domain, said virtual link comprising a series of component links,

said first node advertising fault recovery type of said virtual link as being equal to fault recovery type of said first and second transport paths,

said first and second nodes of each of said domains accommodating said traffic path in the second transport path of the domain when the first transport path of the domain is not working properly.

22. The multi-domain communications network of claim 19 or 20, wherein said first and second fault recovery layers are hierarchically structured in such a relationship that no contention occurs between the first and second fault recovery layers when a failure occurs in said first and second transport paths.

23. The multi-domain communications network of claim 19 or 20, wherein each of said nodes comprises:

a first table memory for storing routing data of said first, second and traffic paths;

a second table memory for storing switching data derived from said routing data;

a switch for terminating said first and second transport paths; and

a controller for establishing a connection in said switch according to said switching data so that said traffic path is accommodated in said first transport path,

said controller responding to an occurrence of a failure in said first transport path for updating said routing data, updating the switching data according to the updated routing data and reestablishing a connection in said switch according to the updated switching data so that said traffic path is accommodated in said second transport path.

24. The multi-domain communications network of claim 23, wherein said controller derives said switching data from said routing data by translation from a control plane of said network to a transport plane of said network.

25. The multi-domain communications network of claim 24, wherein said controller updates said routing data when said failure is detected in said first transport path, updates said switching data according to the updated routing data and reestablishes said connection according to the updated switching data.

26. The multi-domain communications network of claim 19 or 20, wherein fault recovery type of the inter-node links of each of said domains is unprotected, and fault recovery type of said first and second transport paths of each of said domains is dedicated 1+1.

27. The multi-domain communications network of claim 19 or 20, wherein fault recovery type of the inter-node links of each of said domains is unprotected, and fault recovery type of said first and second transport paths of each of said domains is dedicated 1:

1.

28. The multi-domain communications network of claim 19 or 20, wherein fault recovery type of the inter-node links of each of said domains is unprotected, and said first and second transport paths of each of said domains are of shared fault recovery type.

29. The multi-domain communications network of claim 19 or 20, wherein each of said inter-domain links is of don'"'"'t care fault recovery type.

30. The multi-domain communications network of claim 19 or 20, wherein said first fault recovery layer is a wavelength layer and said second fault recovery layer is a TDM (time division multiplex) layer.

31. The multi-domain communications network of claim 19 or 20, wherein said domains comprise first and second domains and an intermediate domain connected between the first and second domains, and wherein said first, second and intermediate domains establish a third transport path on a third fault recovery layer between the second node of said first domain and the first node of said third domain through the first transport path of said intermediate domain.

32. The multi-domain communications network of claim 31, wherein the first fault recovery layer of said intermediate domain is a TDM layer and said third fault recovery layer is a wavelength layer.

33. The multi-domain communications network of claim 19 or 20, wherein the first and second nodes of each of said domains transmits a request message downstream to, and receives the request message from, an adjacent node for establishing said first and second transport paths in each of the domains and specifying a particular fault recovery type and a bandwidth resource of the established transport paths and transmits a return message upstream to, and receives the return message from, an adjacent node,

each of said nodes setting the fault recovery type specified in the received request message into a first table memory and setting an input and output connectivity in said first table memory by associating information contained in the received request message and information contained in the received return message,

each of said nodes creating a switch table according to information contained in the first table memory,

each of said nodes including a switch for establishing a connection according to said switch table for transporting signals of said traffic path.

34. The multi-domain communications network of claim 19 or 20, wherein the first and second nodes of each of said domains transmits a first request message downstream to, and receives the first request message from, an adjacent node for establishing said first and second transport paths using protected inter-domain links,

wherein each of said nodes determines whether or not a transport path specified by the received request message is discovered, and

wherein, if the specified transport path is not discovered, each of said nodes transmits a second request message downstream to, and receives the second request message from, an adjacent node for establishing said first and second transport paths using unprotected inter-domain links.

35. The multi-domain communications network of claim 19 or 20, wherein each of said first and second transport paths is a wavelength path.

20. A multi-domain communications network comprising:

a plurality of network domains interconnected by inter-domain links, each of said network domains including first and second nodes interconnected by inter-node links; and

a traffic path established between a source node and a destination node,

the first node of each of said domains establishing first and second parallel transport paths on a first fault recovery layer to the second node of the domain and including a database for storing identities of said first and second parallel transport paths as a single virtual link as viewed from said source node, and accommodating said traffic path on a second fault recovery layer through the first transport path of the domain, said virtual link comprising a series of component links,

said first node advertising fault recovery type of said virtual link as being equal to most unreliable fault recovery type of said component links,

said first and second nodes of each of said domains accommodating said traffic path in the second transport path of the domain when the first transport path of the domain is not working properly.

21. The multi-domain communications network of claim 20, wherein said first node advertises fault recovery type of said virtual link as being equal to fault recovery type of said first and second transport paths.

36. A fault recovery method for a communications network in which first and second nodes are interconnected by communication links, the method comprising the steps of:

establishing first and second parallel transport paths on a first fault recovery layer between the first and second nodes;

storing identities of said first and second parallel transport paths in a database as a single virtual link as viewed from a source node;

advertising fault recovery type of said virtual link as being equal to fault recovery type of said first and second transport paths;

establishing a traffic path between a source node and a destination node;

accommodating said traffic path on a second fault recovery layer through said first transport path; and

monitoring said first transport path, at said second node, and accommodating said traffic path on said second fault recovery layer through said second transport path when a failure is detected in said first path.

39. The fault recovery method of claim 36 or 37, wherein said first and second fault recovery layers are hierarchically structured in such a relationship that no contention occurs between the first and second fault recovery layers when a failure occurs in said first and second transport paths.

40. The fault recovery method of claim 36 or 37, further comprising the steps of:

supplying a signal of said traffic path from said first node to said first and second transport paths simultaneously, and receiving the signal at said second node from said first transport path when the first transport path is working properly; and

receiving said signal at said second node from said second transport path when said failure is detected in said first transport path.

41. The fault recovery method of claim 36 or 37, further comprising the steps of:

supplying a signal of said traffic path from said first node to said first transport path and receiving said signal at said second node from said first transport path when the first transport path is working properly; and

supplying said signal from said first node to said second transport path and receiving said signal at said second from said second transport path when said failure is detected in said first transport path.

42. The fault recovery method of claim 36 or 37, further comprising the steps of:

supplying a signal of said traffic path from said first node to said first transport path and receiving said signal from said first transport path at said second node when the first transport path is working properly; and

supplying said signal to said first and second transport paths simultaneously from said first node and receiving said signal from said second transport path at said second node when said failure is detected in said first transport path.

43. The fault recovery method of claim 36 or 37, further comprising the steps of:

a) storing routing data of said first, second and traffic paths in a first table memory;

b) storing switching data derived from said routing data in a second table memory;

c) terminating said first and second transport paths to a switch;

d) establishing a connection in said switch according to said switching data so that said traffic path is accommodated in said first transport path;

e) updating said routing data when a failure occurs in said first transport path;

f) updating the switching data according to the updated routing data; and

g) reestablishing a connection in said switch according to the updated switching data so that said traffic path is accommodated in said second transport path.

44. The fault recovery method of claim 43, wherein step (b) comprises deriving said switching data from said routing data by translation from a control plane of said network to a transport plane of said network.

45. The fault recovery method of claim 44, wherein said control plane is a GMPLS (generalized multi-protocol label switching) system and said transport plane is an SDH/SONET system.

46. The fault recovery method of claim 44, further comprising the steps of:

updating said routing data when said failure is detected in said first transport path;

updating said switching data according to the updated routing data; and

reestablishing said connection according to the updated switching data.

47. The fault recovery method of claim 36 or 37, wherein said communications network is a multi-domain communications network wherein a plurality of network domains are interconnected by inter-domain links, and further comprising the steps of:

transmitting a request message from each of said nodes downstream to, and receiving the request message from, an adjacent node for establishing said first and second transport paths in each of the domains by specifying a particular fault recovery type and a bandwidth resource of the established transport paths;

transmitting a return message upstream to, and receives the return message from, an adjacent node;

setting the fault recovery type specified in the received request message into a first table memory of each node and setting an input and output connectivity in said first table memory by associating information contained in the received request message and information contained in the received return message;

creating a second table memory, in each node, according to information contained in the first table memory of the node; and

establishing a connection in each of said nodes according to the second table memory of the node for transporting signals on said traffic path.

48. The fault recovery method of claim 36 or 37, wherein said communications network is a multi-domain communications network wherein a plurality of network domains are interconnected by inter-domain links, and further comprising the steps of:

transmitting a first request message from each of said nodes downstream to, and receives the first request message from, an adjacent node for establishing said first and second transport paths using protected inter-domain links;

determining whether or not a transport path specified by the received request message is discovered; and

if the specified transport path is not discovered, transmitting a second request message from each node downstream to, and receiving the second request message from, an adjacent node for establishing said first and second transport paths using unprotected inter-domain links.

37. A fault recovery method for a communications network in which first and second nodes are interconnected by communication links, the method comprising the steps of:

establishing first and second parallel transport paths on a first fault recovery layer between the first and second nodes;

storing identities of said first and second parallel transport paths in a database as a single virtual link as viewed from a source node, said virtual link comprising a series of component links;

advertising fault recovery type of said virtual link as being equal to most unreliable fault recovery type of said component links;

establishing a traffic path between a source node and a destination node;

accommodating said traffic path on a second fault recovery layer through said first transport path; and

monitoring said first transport path, at said second node, and accommodating said traffic path on said second fault recovery layer through said second transport path when a failure is detected in said first path.

38. The fault recovery method of claim 37, further comprising the step of advertising fault recovery type of said virtual link as being equal to fault recovery type of said first and second transport paths.