System and method for preventing erroneous link aggregation due to component relocation

• US 20060039384A1
• Filed: 08/17/2004
• Published: 02/23/2006
• Est. Priority Date: 08/17/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Dontu, Sitaram, Finn, Norman W., D'Souza, Nelson B.
• Granted Patent: US 8,730,976 B2
• Time in Patent Office: Days
• US Class Current: 370/400
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/245 Link aggregation, e.g. trunking
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Various methods and systems for preventing erroneous link aggregation due to component relocation are disclosed. Such methods include a method for changing the identifier used by a network device and communicating the identifier change to a peer network device without disrupting an aggregated link. In one embodiment, a method involves detecting an identifier change and sending a Port Aggregation Protocol (PAgP) protocol data unit (PDU) that includes a new identifier and information. The information indicates the identifier change. The new identifier identifies a network device subsequent to the identifier change. Another embodiment of a method involves detecting an identifier change and, subsequent to the identifier change, sending a link aggregation protocol PDU that includes an “old device identifier” field dedicated to conveying an old identifier. The old identifier identifies a network device prior to the identifier change.

Claims

1. A method comprising:

detecting an identifier change; and

sending a Port Aggregation Protocol (PAgP) protocol data unit (PDU), wherein

the PAgP PDU comprises a new identifier and information, and

the information indicates the identifier change.

2. The method of claim 1, wherein

the new identifier identifies a network device subsequent to the identifier change,

the PAgP PDU comprises an “

old device identifier”

field,

the “

old device identifier”

field of the PAgP PDU comprises the information,

the information comprises an old identifier, and

the old identifier identifies the network device prior to the identifier change.

3. The method of claim 2, further comprising:

sending a second PAgP PDU, wherein

the second PAgP PDU does not include the “

old device identifier”

field, and

the sending the second PAgP PDU occurs prior to the detecting.

4. The method of claim 2, further comprising:

updating a value of a flag, in response to the detecting, wherein

the updated value of the flag indicates that the information should be included in one or more PAgP PDUs.

5. The method of claim 4, further comprising:

receiving a second PAgP PDU subsequent to the updating the value of the flag, and

preventing an interface from being removed from an aggregated interface, in response

to receiving the second PAgP PDU, wherein

the second PAgP PDU comprises the old identifier, and

the second PAgP PDU is received by the interface.

6. The method of claim 2, wherein the new identifier is a Media Access Control (MAC) address.

7. The method of claim 2, further comprising:

sending a second PAgP PDU subsequent to the detecting the identifier change, wherein

the second PAgP PDU comprises the new identifier, and

the second PAgP PDU does not comprise the “

old device identifier”

field, unless the second PAgP PDU is sent via an aggregated interface.

8. The method of claim 1, further comprising:

detecting whether a partner interface is executing a compatible version of PAgP, wherein

the PAgP PDU is sent via an interface, and

the partner interface is coupled to the interface by a link.

9. The method of claim 8, further comprising:

providing the compatible version of PAgP to the partner interface via the link, if the partner interface is not executing the compatible version.

10. The method of claim 8, further comprising:

inhibiting the partner interface from including the link in an aggregated link if the partner interface is not executing the compatible version of PAgP.

11. A method comprising:

receiving a PAgP PDU via an interface, wherein

the PAgP PDU comprises a new identifier; and

removing the interface from an aggregated interface in response to the new identifier, unless the PAgP PDU comprises information indicating an identifier change.

12. The method of claim 11, wherein

the new identifier identifies a network device subsequent to the identifier change,

the PAgP PDU comprises an “

old device identifier”

field,

the “

old device identifier”

field of the PAgP PDU comprises the information,

the information comprises an old identifier, and

the old identifier identifies the network device prior to the identifier change.

13. The method of claim 12, further comprising:

receiving a second PAgP PDU, wherein

the second PAgP PDU does not include the “

old device identifier”

field, and

the second PAgP PDU is received prior to the PAgP PDU.

14. The method of claim 13, further comprising:

updating a stored identifier to equal the new identifier if the PAgP PDU comprises the information.

15. The method of claim 12, further comprising:

setting a flag associated with a second interface if the PAgP PDU comprises the information, wherein

the aggregated link comprises the interface and the second interface.

16. The method of claim 15, further comprising:

resetting the flag in response to the second interface receiving a second PAgP PDU, wherein

the second PAgP PDU comprises the new identifier.

17. A method comprising:

using a first identifier to identify both a first interface of a first component and a second interface of a second component in a PAgP PDU sent via the first interface and in a PAgP PDU sent via the second interface; and

causing at least one interface of the first interface and the second interface to use a second identifier in a second PAgP PDU sent via the at least one interface, if the first component is moved to a different location in a network.

18. The method of claim 17 wherein the causing the at least one interface of the first interface and the second interface to use the second identifier comprises:

prompting a network administrator to enter a media access control (MAC) address for use by the first interface, in response to the first component being moved to a different location in the network; and

the first interface using the new MAC address as the second identifier in the second PAgP PDU sent via the first interface.

19. The method of claim 17 wherein the causing the at least one interface of the first interface and the second interface to use the second identifier comprises:

detecting a trigger condition; and

the second interface including the second identifier in the second PAgP PDU, in response to the detecting the trigger condition.

20. The method of claim 19, wherein

the trigger condition comprises detection of a failover from the first component to the second component.

21. The method of claim 20, wherein

the first identifier is a MAC address of the first component.

the second identifier is a MAC address of the second component.

22. The method of claim 18, further comprising:

sending the second PAgP PDU via the second interface, subsequent to the detecting the trigger condition, wherein

the second PAgP PDU comprises the second identifier and information,

the information indicates that an identifier change is occurring.

23. The method of claim 22, wherein

the information comprises the first identifier.

24. A method comprising:

detecting an identifier change, wherein

a network device component is identified by an old identifier prior to the identifier change, and

the network device component is identified by a new identifier subsequent to the identifier change; and

sending a link aggregation protocol PDU, subsequent to the detecting the identifier change, wherein

the link aggregation protocol PDU comprises an “

old device identifier”

field dedicated to conveying the old identifier.

25. The method of claim 24, wherein

the “

old device identifier”

field is encoded as a Type, Length, and Value (TLV), a type portion of the TLV identifies that the TLV is an old device identifier field.

26. The method of claim 25, wherein the link aggregation protocol is PAgP.

27. The method of claim 25, further comprising:

sending a second link aggregation protocol PDU, wherein

the second link aggregation protocol PDU does not comprise the “

old device identifier”

field, and

the second link aggregation protocol PDU is sent prior to the detecting the identifier change.

28. The method of claim 25, wherein the network device component is a virtual network device sub-unit.

29. A system comprising:

a first network device; and

a second network device coupled to the first network device, wherein

the first network device comprises a first interface configured to detect an identifier change and to send a link aggregation protocol PDU to the second network device, wherein

the first interface is identified by an old identifier prior to an identifier change,

the network device component is identified by a new identifier subsequent to the identifier change, and

the link aggregation protocol PDU comprises an “

old device identifier”

field dedicated to conveying the old identifier.

30. The system of claim 29, wherein

the “

old device identifier”

field is encoded as a Type, Length, and Value (TLV),

a type portion of the TLV identifies that the TLV is an old device identifier field.

31. The system of claim 30, wherein the link aggregation protocol is PAgP.

32. The system of claim 31, wherein

the interface is configured to send a second link aggregation protocol PDU to the second network device, wherein

the second link aggregation protocol PDU does not comprise the “

old device identifier”

field, and

the second link aggregation protocol PDU is sent prior to the detecting the identifier change.

33. The system of claim 31, wherein

the second network device comprises a second interface configured to receive one or more link aggregation protocol PDUs from the first network device, and

the second network device is configured to remove the second interface from an aggregated interface in response to one of the one or more link aggregation protocol PDUs comprising a new identifier, unless the one of the one or more link aggregation protocol PDUs also comprises the “

old device identifier”

field.

34. A network device comprising:

an interface comprising a protocol data unit (PDU) handling module, wherein

the PDU handling module is configured to send a link aggregation protocol PDU comprising an “

old device identifier”

field,

the “

old identifier field”

is dedicated to conveying an old identifier, and

the old identifier identifies the interface prior to an identifier change.

35. The network device of claim 34, wherein

the link aggregation protocol PDU is a PAgP PDU.

36. The network device of claim 35, wherein

the PDU handling module is configured to send the link aggregation protocol PDU in response to detecting the identifier change.

37. The network device of claim 36, wherein

the PDU handling module is configured to send a second link aggregation protocol PDU prior to detecting the identifier change, and

the second link aggregation protocol PDU does not include the “

old device identifier”

field.

38. The network device of claim 35, wherein

the PDU handling module is configured to receive a second link aggregation protocol PDU, and

the PDU handling module is configured to remove the interface from an aggregated interface if the second link aggregation protocol PDU comprises a new identifier, unless the second link aggregation protocol PDU also comprises the “

old device identifier”

field.

39. A network device comprising:

an interface comprising a protocol data unit (PDU) handling module, wherein

the PDU handling module is configured to;

receive a link aggregation protocol PDU; and

remove the interface from an aggregated interface if the link aggregation protocol PDU comprises a new identifier, unless the link aggregation protocol PDU also comprises an “

old device identifier”

field.

40. The network device of claim 39, wherein

the link aggregation protocol PDU is a PAgP PDU.

41. The network device of claim 40, wherein

the PDU handling module is further configured to send a second link aggregation protocol PDU comprising the “

old device identifier”

field in response to detecting an identifier change,

the “

old identifier field”

is dedicated to conveying an old identifier, and

the old identifier identifies the interface prior to the identifier change.

42. A network device comprising:

an interface comprising a port aggregation protocol (PAgP) protocol data unit (PDU) handling module, wherein

the PAgP PDU handling module is configured to send a PAgP PDU comprising a new identifier and information, and

the information is indicative of the identifier change.

43. The network device of claim 42, wherein

the new identifier identifies the interface subsequent to the identifier change,

the PAgP PDU comprises an “

old device identifier”

field,

the “

old device identifier”

field of the PAgP PDU comprises the information,

the information comprises an old identifier, and

the old identifier identifies the interface prior to the identifier change.

44. The network device of claim 43, wherein

the PAgP PDU handling module is configured to send a second PAgP PDU, wherein the second PAgP PDU does not include the “

old device identifier”

field, and

the second PAgP PDU is sent prior to the identifier change.

45. The network device of claim 43, wherein

the PAgP PDU handling module is configured to update a value of a flag, in response to the identifier change, wherein

the updated value of the flag indicates that the information should be included in one or more PAgP PDUs.

46. The network device of claim 45, wherein

the PAgP handling module is configured to:

receive a second PAgP PDU subsequent to the updating the value of the flag, and

prevent the interface from being removed from an aggregated interface, in response to receipt of the second PAgP PDU, wherein

the second PAgP PDU comprises the old identifier, and

the second PAgP PDU is received via the interface.

47. The network device of claim 43, wherein the identifier is a Media Access Control (MAC) address.

48. The network device of claim 43, wherein

the PAgP PDU handling module is configured to send a second PAgP PDU subsequent to the identifier change, wherein

the second PAgP PDU comprises the new identifier, and

the second PAgP PDU does not comprise the “

old device identifier”

field, unless the second PAgP PDU is sent via an aggregated interface.

49. The network device of claim 42, wherein

the interface is configured to detect whether a partner interface is executing a compatible version of PAgP, wherein

the partner interface is coupled to the interface by a link.

50. The network device of claim 49, wherein

the interface is configured to provide the compatible version of PAgP to the partner interface via the link, if the partner interface is not executing the compatible version.

51. The network device of claim 49, wherein

the interface is configured to inhibit the partner interface from including the link in an aggregated link if the partner interface is not executing the compatible version of PAgP.

52. A network device comprising:

an interface comprising a port aggregation protocol (PAgP) protocol data unit (PDU) handling module, wherein

the PAgP PDU handling module is configured to;

receive a PAgP PDU; and

remove the interface from an aggregated interface if the PAgP PDU comprises a new identifier, unless the PAgP PDU comprises information indicating an identifier change.

53. The network device of claim 52, wherein

the new identifier identifies the interface subsequent to the identifier change,

the PAgP PDU comprises an “

old device identifier”

field,

the “

old device identifier”

field of the PAgP PDU comprises the information,

the information comprises an old identifier, and

the old identifier identifies the network device prior to the identifier change.

54. The network device of claim 53, wherein

the PAgP PDU handling module is configured to receive a second PAgP PDU, wherein

the second PAgP PDU does not include the “

old device identifier”

field, and

the second PAgP PDU is received prior to the PAgP PDU.

55. A network device comprising:

a first component comprising a first interface, wherein

the first interface is configured to;

use a first identifier to identify the first interface in a PAgP PDU sent via the first interface; and

a second component coupled to the first component, wherein

the second component comprises a second interface configured to use the first identifier to identify the second interface in a second PAgP PDU sent via the second interface, and

at least one of the first component and the second component is configured to cause at least one interface of the first interface and the second interface to use a second identifier in a third PAgP PDU sent via the at least one interface, if the first component is moved to a different location in a network.

56. The network device of claim 55, wherein

the first component is configured to prompt a network administrator to enter a media access control (MAC) address for use by the first interface, in response to the first component being moved to the different location in the network, and

the first interface is configured to use the new MAC address as the second identifier in the third PAgP PDU sent via the first interface.

57. The network device of claim 55, wherein

the second interface is configured to detect a trigger condition, and

the second interface is configured to use the second identifier in the third PAgP PDU, in response to the detecting the trigger condition.

58. The network device of claim 57, wherein

the trigger condition comprises detection of a failover from the first component to the second component.

59. A computer readable medium comprising program instructions executable to:

detect an identifier change, wherein

a network device component is identified by an old identifier prior to the identifier change, and

the network device component is identified by a new identifier subsequent to the identifier change; and

send a link aggregation protocol PDU, in response to the identifier change, wherein

the link aggregation protocol PDU comprises an “

old device identifier”

field dedicated to conveying the old identifier.

60. The computer readable medium of claim 59, wherein

the “

old device identifier”

field is encoded as a Type, Length, and Value (TLV),

a type portion of the TLV identifies that the TLV is an old device identifier field.

61. The computer readable medium of claim 60, wherein the link aggregation protocol is PAgP.

62. The computer readable medium of claim 60, wherein the program instructions are further executable to:

send a second link aggregation protocol PDU, wherein

the second link aggregation protocol PDU does not comprise the “

old device identifier”

field, and

the second link aggregation protocol PDU is sent prior to the identifier change.

63. A system comprising:

means for detecting an identifier change, wherein

a network device component is identified by an old identifier prior to the identifier change, and

the network device component is identified by a new identifier subsequent to the identifier change; and

means for sending a link aggregation protocol PDU, in response to the identifier change, wherein

the link aggregation protocol PDU comprises an “

old device identifier”

field dedicated to conveying the old identifier.

64. The system of claim 63, wherein

the “

old device identifier”

field is encoded as a Type, Length, and Value (TLV),

a type portion of the TLV identifies that the TLV is an old device identifier field.

65. The system of claim 64, wherein the link aggregation protocol is PAgP.

66. The system of claim 64, further comprising:

means for sending a second link aggregation protocol PDU, wherein

the second link aggregation protocol PDU does not comprise the “

old device identifier”

field, and

the second link aggregation protocol PDU is sent prior to the identifier change.