Method for restoring a virtual path in an optical network using 1:N protection

• US 20050036442A1
• Filed: 06/07/2001
• Published: 02/17/2005
• Est. Priority Date: 05/16/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Parsi, Vahid, Baghdasarian, Zareh, Zadikian, H. Michael, Saleh, Ali Najib
• Granted Patent: US 7,477,594 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• CPC Class Codes: H04J 14/0284 WDM mesh architectures
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)
• CPC Class Codes: H04L 41/0663 Performing the actions predefined by failover planning, e.g. switching to standby network elements
• CPC Class Codes: H04L 41/0681 Configuration of triggering conditions
• CPC Class Codes: H04L 41/5054 Automatic deployment of services triggered by the service manager, e.g. service implementation by automatic configuration of network components
• CPC Class Codes: H04L 41/5077 wherein the managed service relates to simple transport services, i.e. providing only network infrastructure
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/302 Route determination based on requested QoS
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04Q 11/0062 Network aspects
• CPC Class Codes: H04Q 2011/0081 Fault tolerance; Redundancy; Recovery; Reconfigurability
• CPC Class Codes: H04Q 2011/0098 Mesh

Abstract

A method for restoring a virtual path, provisioned between a source and a target node, in a zoned mesh optical network is described. The method, in one embodiment, allocates a primary and a secondary physical path to the virtual path. The two physical paths are node and link disjoint. In case of a failure on one physical path, the network switches the virtual path to the other physical path. The alternate path can be shared among various virtual paths during the restoration.

Claims

1. A method for restoring a virtual path in an optical network, the method comprising:

identifying a plurality of nodes with resources, wherein said nodes with resources are ones of said nodes having a resource necessary to support said virtual path;

provisioning a first physical path for said virtual path, said first physical path comprising ones of said nodes with resources; and

reserving a resource for a second physical path for said virtual path at ones of said nodes having said resource necessary to support said virtual path.

2. The method of claim 1, further comprising:

restoring said virtual path by provisioning said second physical path on said reserved resource.

3. The method of claim 2, wherein said restoring is done by

identifying one of said first physical path and said second physical path experiencing a failure, and

switching said virtual path to one of said first physical path and said second physical path not experiencing a failure.

4. The method of claim 3, further comprising:

detecting a failure in said virtual path wherein said detection of said failure is done by receiving a failure message packet.

5. The method of claim 4, wherein

said first physical path and said second physical path are provisioned between a first and a second node of said optical network,

said first physical path and said second physical path between said first and said second node comprise a plurality of intermediate nodes,

said first physical path and said second physical path are link and intermediate node disjoint,

said optical network comprises said nodes,

each one of said nodes is coupled to at least one another of said nodes by a plurality of optical links, and

said virtual path is provisioned on one of said first physical path and said second physical path.

6. The method of claim 5, wherein each one of said nodes is coupled to at least one another of said nodes in a mesh topology.

7. The method of claim 6, wherein said restoring of said virtual path is completed in less than 2 seconds.

8. The method of claim 6, wherein said restoring of said virtual path is completed in less than 250 milliseconds.

9. The method of claim 6, wherein said restoring of said virtual path is completed in less than 50 milliseconds.

10. The method of claim 6, wherein said second physical path is shared by a plurality of other virtual paths.

11. The method of claim 10, wherein one of said first physical path and said second physical path which is not used by one of said virtual path and said plurality of other virtual paths is used by a protection channel access traffic.

12. The method of claim 11, further comprising:

if one of said plurality of intermediate nodes and said second node receives said failure message,

changing a state of said virtual path to down, and

forwarding said failure message to said first node.

13. The method of claim 6, further comprising:

if said first node receives said failure message,

identifying one of said first physical path and said second physical path with no failure.

14. The method of claim 13, further comprising:

if said protection channel access traffic is using said one of said first physical path and said second physical path with no failure,

disconnecting said protection channel access traffic, and

generating an alarm for said protection channel access traffic; and

if said protection channel access traffic is not using said one of said first physical path and said second physical path with no failure,

changing a state of said virtual path to restoring,

(i) forwarding a switch path request packet to nodes on said one of said first physical path and said second physical path with no failure,

(ii) waiting for a switch path response packet for a predetermined time interval, and

if said switch path response packet is not received within said predetermined time interval,

repeating steps (i)-(ii) for a predefined threshold times.

15. The method of claim 14, further comprising:

if said switch path response packet is not received within said predefined threshold times,

generating a network alarm;

if said switch path response packet is received within said predefined threshold times with no errors,

switching said virtual path on a list of allocated ports contained in said switch path response packet; and

if said switch path response packet is received within said predefined threshold times with at least one error,

waiting until responses to all said switch path request packets are received.

16. The method of claim 14, further comprising:

if responses to all said switch path request packets are received with at least one error,

generating a network alarm.

17. The method of claim 14, wherein said predetermined time interval and predefined threshold are defined during provisioning of said virtual path.

18. The method of claim 14, wherein said predetermined time interval and predefined threshold are dynamically calculated by said network based on network traffic condition.

19. The method of claim 14, wherein one of said plurality of intermediate nodes receives said switch path request packet.

20. The method of claim 19, further comprising:

if a resource is not available for said virtual path,

copying said switch path request packet to a switch path response packet,

decrementing a hop count field in said switch path response packet,

adding an error code to said switch path response packet, and

responding with said switch path response packet.

21. The method of claim 19, further comprising:

if said switch path request packet is received with at least one error,

copying said switch path request packet to a switch path response packet,

decrementing a hop count field in said switch path response packet,

adding an error code to said switch path response packet, and

responding with said switch path response packet; and

if said switch path request packet is received with no error,

determining whether said protection channel access traffic is using a requested resource for said virtual path.

22. The method of claim 21, further comprising:

if said protection channel access traffic is using said requested resource for said virtual path,

disconnecting said protection channel access traffic, and

generating an alarm for said protection channel access traffic;

if said protection channel access traffic is not using said requested resource for said virtual path,

allocating said resource to said virtual path,

incrementing a hop count field in said switch path request packet,

changing a state of said virtual path to restoring,

forwarding said switch path request packet to an adjacent node comprising said virtual path, and

waiting for a switch path response packet from said adjacent node.

23. The method of claim 22, further comprising:

if said switch path response packet is not received within a predetermined time interval,

forwarding a negative acknowledgment to said first node.

24. The method of claim 22, further comprising:

if said switch path response packet is received with no errors,

updating said virtual path information in a node database,

assigning a plurality of ports to said virtual path,

decrementing a hop count field in said switch path response packet, and

forwarding said switch path response packet to said first node; and

if said switch path response packet is received with at least one error,

comparing an attempt count field of said switch path response packet with an attempt count field of a switch path request packet previously forwarded by said intermediate node.

25. The method of claim 24, further comprising:

if said attempt count field of said switch path response packet is lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node,

ignoring said switch path response packet; and

if said attempt count field of said switch path response packet is not lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node,

decrementing a hop count field in said switch path response packet, and

forwarding said switch path response packet to said first node.

26. The method of claim 14, wherein said second node receives said switch path request packet.

27. The method of claim 26, further comprising:

if a resource is not available for said virtual path,

copying said switch path request packet to a switch path response packet,

decrementing a hop count field in said switch path response packet,

adding an error code to said switch path response packet, and

responding with said switch path response packet.

28. The method of claim 26, further comprising:

if said switch path request packet is received with at least one error,

copying said switch path request packet to a switch path response packet,

decrementing a hop count field in said switch path response packet,

adding an error code to said switch path response packet, and

responding with said switch path response packet; and

if said switch path request packet is received with no error,

determining whether said protection channel access traffic is using a requested resource for said virtual path.

29. The method of claim 28, further comprising:

if said protection channel access traffic is using said requested resource for said virtual path,

disconnecting said protection channel access traffic,

generating an alarm for said protection channel access traffic; and

if said protection channel access traffic is not using said requested resource for said virtual path,

copying said switch path request packet to a switch path response packet,

updating said virtual path information in a node database,

assigning a plurality of ports to said virtual path,

decrementing a hop count field in said switch path request packet,

changing a state of said virtual path to restoring, and

responding with said switch path response packet.

30. A network element configured to restore a virtual path in an optical network, the network element comprising:

a processor, said processor configured to

identify a plurality of nodes with resources, wherein said nodes with resources are ones of said nodes having a resource necessary to support said virtual path,

provision a first physical path for said virtual path, said first physical path comprising ones of said nodes with resources,

reserve a resource for a second physical path for said virtual path at ones of said nodes having said resource necessary to support said virtual path, and

restore said virtual path by provisioning said second physical path on said reserved resource.

31. The network element of claim 30, wherein said processor is further configured to

identify one of said first physical path and said second physical path experiencing a failure, and

switch said virtual path to one of said first physical path and said second physical path not experiencing a failure.

32. The network element of claim 30, wherein said processor is further configured to receive a failure message to detect a failure in said virtual path.

33. The network element of claim 32, wherein

said first physical path and said second physical path are provisioned between a first and a second node of said optical network,

said first physical path and said second physical path between said first and said second node comprise a plurality of intermediate nodes,

said first physical path and said second physical path are link and intermediate node disjoint,

said optical network comprises said nodes,

each one of said nodes is coupled to at least one another of said nodes by a plurality of optical links, and

said virtual path is provisioned on one of said first physical path and said second physical path.

34. The network element of claim 33, wherein each one of said nodes is coupled to at least one another of said nodes in a mesh topology.

35. The network element of claim 34, wherein said processor is further configured to restore said virtual path in less than 2 seconds.

36. The network element of claim 34, wherein said processor is further configured to restore said virtual path in less than 250 milliseconds.

37. The network element of claim 34, wherein said processor is further configured to restore said virtual path in less than 50 milliseconds.

38. The network element of claim 34, wherein said second physical path is shared by a plurality of other virtual paths.

39. The network element of claim 38, wherein one of said first physical path and said second physical path which is not used by one of said virtual path and said plurality of other virtual paths is used by a protection channel access traffic.

40. The network element of claim 39, wherein said processor is configured as one of said plurality of intermediate nodes and said second node, and if said processor receives said failure message, the processor is further configured to

change a state of said virtual path to down, and

forward said failure message to said first node.

41. The network element of claim 34, wherein said processor is configured as said first node and if said processor receives said failure message, the processor is further configured to

identify one of said first physical path and said second physical path with no failure.

42. The network element of claim 41, wherein said processor is further configured to:

if said protection channel access traffic is using said one of said first physical path and said second physical path with no failure,

disconnect said protection channel access traffic, and

generate an alarm for said protection channel access traffic; and

if said protection channel access traffic is not using said one of said first physical path and said second physical path with no failure,

change a state of said virtual path to restoring,

(i) forward a switch path request packet to nodes on said one of said first physical path and said second physical path with no failure,

(ii) wait for a switch path response packet for a predetermined time interval, and

if said switch path response packet is not received within said predetermined time interval,

repeat steps (i)-(ii) for a predefined threshold times.

43. The network element of claim 42, wherein said processor is further configured to

if said switch path response packet is not received within said predefined threshold times,

generate a network alarm;

if said switch path response packet is received within said predefined threshold times with no errors,

switch said virtual path on a list of allocated ports contained in said switch path response packet; and

if said switch path response packet is received within said predefined threshold times with at least one error,

wait until responses to all said switch path request packets are received.

44. The network element of claim 42, wherein said processor is further configured to

if responses to all said switch path request packets are received with at least one error,

generate a network alarm.

45. The network element of claim 42, wherein said predetermined time interval and predefined threshold are defined during provisioning of said virtual path.

46. The network element of claim 42, wherein said predetermined time interval and predefined threshold are dynamically calculated by said network based on network traffic condition.

47. The network element of claim 42, wherein

said processor is configured as one of said plurality of intermediate nodes, and

said processor receives said switch path request packet.

48. The network element of claim 47, wherein said processor is further configured to

if a resource is not available for said virtual path,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet.

49. The network element of claim 47, wherein said processor is further configured to

if said switch path request packet is received with at least one error,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet;

and

if said switch path request packet is received with no error,

determine whether said protection channel access traffic is using a requested resource for said virtual path.

50. The network element of claim 49, wherein said processor is further configured to

if said protection channel access traffic is using said requested resource for said virtual path,

disconnect said protection channel access traffic, and

generate an alarm for said protection channel access traffic;

if said protection channel access traffic is not using said requested resource for said virtual path,

allocate said resource to said virtual path,

increment a hop count field in said switch path request packet,

change a state of said virtual path to restoring,

forward said switch path request packet to an adjacent node comprising said virtual path, and

wait for a switch path response packet from said adjacent node.

51. The network element of claim 50, wherein said processor is further configured to

if said switch path response packet is not received within a predetermined time interval,

forward a negative acknowledgment to said first node.

52. The network element of claim 50, wherein said processor is further configured to

if said switch path response packet is received with no errors,

update said virtual path information in a node database,

assign a plurality of ports to said virtual path,

decrement a hop count field in said switch path response packet, and

forward said switch path response packet to said first node;

and

if said switch path response packet is received with at least one error,

compare an attempt count field of said switch path response packet with an attempt count field of a switch path request packet previously forwarded by said intermediate node.

53. The network element of claim 52, wherein said processor is further configured to

if said attempt count field of said switch path response packet is lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node,

ignore said switch path response packet;

and

if said attempt count field of said switch path response packet is not lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node,

decrement a hop count field in said switch path response packet, and

forward said switch path response packet to said first node.

54. The network element of claim 42, wherein

said processor is configured as said second node, and

said processor receives said switch path request packet.

55. The network element of claim 54, wherein said processor is further configured to

if a resource is not available for said virtual path,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet.

56. The network element of claim 54, wherein said processor is further configured to

if said switch path request packet is received with at least one error,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet;

and

if said switch path request packet is received with no error,

determine whether said protection channel access traffic is using a requested resource for said virtual path.

57. The network element of claim 56, wherein said processor is further configured to

if said protection channel access traffic is using said requested resource for said virtual path,

disconnect said protection channel access traffic,

generate an alarm for said protection channel access traffic;

and

if said protection channel access traffic is not using said requested resource for said virtual path,

copy said switch path request packet to a switch path response packet,

update said virtual path information in a node database,

assign a plurality of ports to said virtual path,

decrement a hop count field in said switch path request packet,

change a state of said virtual path to restoring, and

respond with said switch path response packet.

58. A computer system for restoring a virtual path in an optical network, said computer system comprising:

means for identifying a plurality of nodes with resources, wherein said nodes with resources are ones of said nodes having a resource necessary to support said virtual path;

means for provisioning a first physical path for said virtual path, said first physical path comprising ones of said nodes with resources;

means for reserving a resource for a second physical path for said virtual path at ones of said nodes having said resource necessary to support said virtual path; and

means for restoring said virtual path by provisioning said second physical path on said reserved resource.

59. The computer system of claim 58, further comprising:

means for identifying one of said first physical path and said second physical path experiencing a failure, and

means for switching said virtual path to one of said first physical path and said second physical path not experiencing a failure.

60. The computer system of claim 59, further comprising:

means for detecting a failure in said virtual path wherein said detection of said failure is done by receiving a failure message packet.

61. The computer system of claim 60, wherein

said first physical path and said second physical path are provisioned between a first and a second node of said optical network,

said first physical path and said second physical path between said first and said second node comprise a plurality of intermediate nodes,

said first physical path and said second physical path are link and intermediate node disjoint,

said optical network comprises said nodes,

each one of said nodes is coupled to at least one another of said nodes by a plurality of optical links, and

said virtual path is provisioned on one of said first physical path and said second physical path.

62. The computer system of claim 61, wherein each one of said nodes is coupled to at least one another of said nodes in a mesh topology.

63. The computer system of claim 62, wherein said restoring of said virtual path is completed in less than 2 seconds.

64. The computer system of claim 62, wherein said restoring of said virtual path is completed in less than 250 milliseconds.

65. The computer system of claim 62, wherein said restoring of said virtual path is completed in less than 50 milliseconds.

66. The computer system of claim 62, wherein said second physical path is shared by a plurality of other virtual paths.

67. The computer system of claim 66, wherein one of said first physical path and said second physical path which is not used by one of said virtual path and said plurality of other virtual paths is used by a protection channel access traffic.

68. The computer system of claim 67, further comprising:

means for changing a state of said virtual path to down if one of said plurality of intermediate nodes and said second node receives said failure message; and

means for forwarding said failure message to said first node if one of said plurality of intermediate nodes and said second node receives said failure message.

69. The computer system of claim 62, further comprising:

means for identifying one of said first physical path and said second physical path with no failure if said first node receives said failure message.

70. The computer system of claim 69, further comprising:

means for disconnecting said protection channel access traffic if said protection channel access traffic is using said one of said first physical path and said second physical path with no failure;

means for generating an alarm for said protection channel access traffic if said protection channel access traffic is using said one of said first physical path and said second physical path with no failure;

means for changing a state of said virtual path to restoring if said protection channel access traffic is not using said one of said first physical path and said second physical path with no failure;

(i) means for forwarding a switch path request packet to nodes on said one of said first physical path and said second physical path with no failure;

(ii) means for waiting for a switch path response packet for a predetermined time interval; and

(iii) means for repeating steps (i)-(ii) for a predefined threshold times if said switch path response packet is not received within said predetermined time interval.

71. The computer system of claim 70, further comprising:

means for generating a network alarm if said switch path response packet is not received within said predefined threshold times;

means for switching said virtual path on a list of allocated ports contained in said switch path response packet if said switch path response packet is received within said predefined threshold times with no errors; and

means for waiting until responses to all said switch path request packets are received if said switch path response packet is received within said predefined threshold times with at least one error.

72. The computer system of claim 70, further comprising:

means for generating a network alarm if responses to all said switch path request packets are received with at least one error.

73. The computer system of claim 70, wherein said predetermined time interval and predefined threshold are defined during provisioning of said virtual path.

74. The computer system of claim 70, wherein said predetermined time interval and predefined threshold are dynamically calculated by said network based on network traffic condition.

75. The computer system of claim 70, wherein one of said plurality of intermediate nodes receives said switch path request packet.

76. The computer system of claim 75, further comprising:

means for copying said switch path request packet to a switch path response packet if a resource is not available for said virtual path;

means for decrementing a hop count field in said switch path response packet if a resource is not available for said virtual path;

means for adding an error code to said switch path response packet if a resource is not available for said virtual path; and

means for responding with said switch path response packet if a resource is not available for said virtual path.

77. The computer system of claim 75, further comprising:

means for copying said switch path request packet to a switch path response packet if said switch path request packet is received with at least one error;

means for decrementing a hop count field in said switch path response packet if said switch path request packet is received with at least one error;

means for adding an error code to said switch path response packet if said switch path request packet is received with at least one error;

means for responding with said switch path response packet if said switch path request packet is received with at least one error;

means for determining whether said protection channel access traffic is using a requested resource for said virtual path if said switch path request packet is received with no error.

78. The computer system of claim 77, further comprising:

means for disconnecting said protection channel access traffic if said protection channel access traffic is using said requested resource for said virtual path;

means for generating an alarm for said protection channel access traffic if said protection channel access traffic is using said requested resource for said virtual path;

means for allocating said resource to said virtual path if said protection channel access traffic is not using said requested resource for said virtual path;

means for incrementing a hop count field in said switch path request packet if said protection channel access traffic is not using said requested resource for said virtual path;

means for changing a state of said virtual path to restoring if said protection channel access traffic is not using said requested resource for said virtual path;

means for forwarding said switch path request packet to an adjacent node comprising said virtual path if said protection channel access traffic is not using said requested resource for said virtual path; and

means for waiting for a switch path response packet from said adjacent node if said protection channel access traffic is not using said requested resource for said virtual path.

79. The computer system of claim 78, further comprising:

means for forwarding a negative acknowledgment to said first node if said switch path response packet is not received within a predetermined time interval.

80. The computer system of claim 78, further comprising:

means for updating said virtual path information in a node database if said switch path response packet is received with no errors;

means for assigning a plurality of ports to said virtual path if said switch path response packet is received with no errors;

means for decrementing a hop count field in said switch path response packet if said switch path response packet is received with no errors;

means for forwarding said switch path response packet to said first node if said switch path response packet is received with no errors; and

means for comparing an attempt count field of said switch path response packet with an attempt count field of a switch path request packet previously forwarded by said intermediate node if said switch path response packet is received with at least one error.

81. The computer system of claim 80, further comprising:

means for ignoring said switch path response packet if said attempt count field of said switch path response packet is lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node;

means for decrementing a hop count field in said switch path response packet if said attempt count field of said switch path response packet is not lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node; and

means for forwarding said switch path response packet to said first node if said attempt count field of said switch path response packet is not lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node.

82. The computer system of claim 70, wherein said second node receives said switch path request packet.

83. The computer system of claim 82, further comprising:

means for copying said switch path request packet to a switch path response packet if a resource is not available for said virtual path;

means for decrementing a hop count field in said switch path response packet if a resource is not available for said virtual path;

means for adding an error code to said switch path response packet if a resource is not available for said virtual path; and

means for responding with said switch path response packet if a resource is not available for said virtual path.

84. The computer system of claim 82, further comprising:

means for copying said switch path request packet to a switch path response packet if said switch path request packet is received with at least one error;

means for decrementing a hop count field in said switch path response packet if said switch path request packet is received with at least one error;

means for adding an error code to said switch path response packet if said switch path request packet is received with at least one error; and

means for responding with said switch path response packet if said switch path request packet is received with at least one error; and

means for determining whether said protection channel access traffic is using a requested resource for said virtual path if said switch path request packet is received with no error.

85. The computer system of claim 84, further comprising:

means for disconnecting said protection channel access traffic if said protection channel access traffic is using said requested resource for said virtual path;

means for generating an alarm for said protection channel access traffic if said protection channel access traffic is using said requested resource for said virtual path;

means for copying said switch path request packet to a switch path response packet if said protection channel access traffic is not using said requested resource for said virtual path;

means for updating said virtual path information in a node database if said protection channel access traffic is not using said requested resource for said virtual path;

means for assigning a plurality of ports to said virtual path if said protection channel access traffic is not using said requested resource for said virtual path;

means for decrementing a hop count field in said switch path request packet if said protection channel access traffic is not using said requested resource for said virtual path;

means for changing a state of said virtual path to restoring if said protection channel access traffic is not using said requested resource for said virtual path; and

means for responding with said switch path response packet if said protection channel access traffic is not using said requested resource for said virtual path.

86. A computer program product for restoring a virtual path in an optical network, encoded in computer readable media, said program product comprising a set of instructions executable on a computer system, said set of instructions configured to

identify a plurality of nodes with resources, wherein said nodes with resources are ones of said nodes having a resource necessary to support said virtual path;

provision a first physical path for said virtual path, said first physical path comprising ones of said nodes with resources;

reserve a resource for a second physical path for said virtual path at ones of said nodes having said resource necessary to support said virtual path; and

restore said virtual path by provisioning said second physical path on said reserved resource.

87. The computer program product of claim 86, wherein said set of instructions is further configured to

identify one of said first physical path and said second physical path experiencing a failure, and

switch said virtual path to one of said first physical path and said second physical path not experiencing a failure.

88. The computer program product of claim 87, wherein said set of instructions is further configured to

detect a failure in said virtual path wherein said detection of said failure is done by receiving a failure message packet.

89. The computer program product of claim 88, wherein

said first physical path and said second physical path are provisioned between a first and a second node of said optical network,

said first physical path and said second physical path between said first and said second node comprise a plurality of intermediate nodes,

said first physical path and said second physical path are link and intermediate node disjoint,

said optical network comprises said nodes,

each one of said nodes is coupled to at least one another of said nodes by a plurality of optical links, and

said virtual path is provisioned on one of said first physical path and said second physical path.

90. The computer program product of claim 89, wherein each one of said nodes is coupled to at least one another of said nodes in a mesh topology.

91. The computer program product of claim 90, wherein said restoring of said virtual path is completed in less than 2 seconds.

92. The computer program product of claim 90, wherein said restoring of said virtual path is completed in less than 250 milliseconds.

93. The computer program product of claim 90, wherein said restoring of said virtual path is completed in less than 50 milliseconds.

94. The computer program product of claim 90, wherein said second physical path is shared by a plurality of other virtual paths.

95. The computer program product of claim 94, wherein one of said first physical path and said second physical path which is not used by one of said virtual path and said plurality of other virtual paths is used by a protection channel access traffic.

96. The computer program product of claim 95, wherein said set of instructions is further configured to

if one of said plurality of intermediate nodes and said second node receives said failure message,

change a state of said virtual path to down, and

forward said failure message to said first node.

97. The computer program product of claim 90, wherein said set of instructions is further configured to

if said first node receives said failure message,

identify one of said first physical path and said second physical path with no failure.

98. The computer program product of claim 97, wherein said set of instructions is further configured to

if said protection channel access traffic is using said one of said first physical path and said second physical path with no failure,

disconnect said protection channel access traffic, and

generate an alarm for said protection channel access traffic;

and

if said protection channel access traffic is not using said one of said first physical path and said second physical path with no failure,

change a state of said virtual path to restoring,

(i) forward a switch path request packet to nodes on said one of said first physical path and said second physical path with no failure,

(ii) wait for a switch path response packet for a predetermined time interval, and

if said switch path response packet is not received within said predetermined time interval,

repeat steps (i)-(ii) for a predefined threshold times.

99. The computer program product of claim 98, wherein said set of instructions is further configured to

if said switch path response packet is not received within said predefined threshold times,

generate a network alarm;

if said switch path response packet is received within said predefined threshold times with no errors,

switch said virtual path on a list of allocated ports contained in said switch path response packet; and

if said switch path response packet is received within said predefined threshold times with at least one error,

wait until responses to all said switch path request packets are received.

100. The computer program product of claim 98, wherein said set of instructions is further configured to

if responses to all said switch path request packets are received with at least one error,

generate a network alarm.

101. The computer program product of claim 98, wherein said predetermined time interval and predefined threshold are defined during provisioning of said virtual path.

102. The computer program product of claim 98, wherein said predetermined time interval and predefined threshold are dynamically calculated by said network based on network traffic condition.

103. The computer program product of claim 98, wherein one of said plurality of intermediate nodes receives said switch path request packet.

104. The computer program product of claim 103, wherein said set of instructions is further configured to

if a resource is not available for said virtual path,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet.

105. The computer program product of claim 103, wherein said set of instructions is further configured to

if said switch path request packet is received with at least one error,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet;

and

if said switch path request packet is received with no error,

determine whether said protection channel access traffic is using a requested resource for said virtual path.

106. The computer program product of claim 105, wherein said set of instructions is further configured to

if said protection channel access traffic is using said requested resource for said virtual path,

disconnect said protection channel access traffic, and

generate an alarm for said protection channel access traffic;

if said protection channel access traffic is not using said requested resource for said virtual path,

allocate said resource to said virtual path,

increment a hop count field in said switch path request packet,

change a state of said virtual path to restoring,

forward said switch path request packet to an adjacent node comprising said virtual path, and

wait for a switch path response packet from said adjacent node.

107. The computer program product of claim 106, wherein said set of instructions is further configured to

if said switch path response packet is not received within a predetermined time interval,

forward a negative acknowledgment to said first node.

108. The computer program product of claim 106, wherein said set of instructions is further configured to

if said switch path response packet is received with no errors,

update said virtual path information in a node database,

assign a plurality of ports to said virtual path,

decrement a hop count field in said switch path response packet, and

forward said switch path response packet to said first node;

and

if said switch path response packet is received with at least one error,

compare an attempt count field of said switch path response packet with an attempt count field of a switch path request packet previously forwarded by said intermediate node.

109. The computer program product of claim 108, wherein said set of instructions is further configured to

if said attempt count field of said switch path response packet is lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node,

ignore said switch path response packet;

and

if said attempt count field of said switch path response packet is not lower than said attempt count field of said switch path request packet previously forwarded by said intermediate node,

decrement a hop count field in said switch path response packet, and

forward said switch path response packet to said first node.

110. The computer program product of claim 98, wherein said second node receives said switch path request packet.

111. The computer program product of claim 110, wherein said set of instructions is further configured to

if a resource is not available for said virtual path,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet.

112. The computer program product of claim 110, wherein said set of instructions is further configured to

if said switch path request packet is received with at least one error,

copy said switch path request packet to a switch path response packet,

decrement a hop count field in said switch path response packet,

add an error code to said switch path response packet, and

respond with said switch path response packet;

and

if said switch path request packet is received with no error,

determine whether said protection channel access traffic is using a requested resource for said virtual path.

113. The computer program product of claim 112, wherein said set of instructions is further configured to

if said protection channel access traffic is using said requested resource for said virtual path,

disconnect said protection channel access traffic,

generate an alarm for said protection channel access traffic;

and

if said protection channel access traffic is not using said requested resource for said virtual path,

copy said switch path request packet to a switch path response packet,

update said virtual path information in a node database,

assign a plurality of ports to said virtual path,

decrement a hop count field in said switch path request packet,

change a state of said virtual path to restoring, and

respond with said switch path response packet.