Redundant power and data in a wired data telecommunincations network

• US 20060077888A1
• Filed: 12/23/2004
• Published: 04/13/2006
• Est. Priority Date: 10/07/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Cafiero, Luca, Karam, Roger A.
• Granted Patent: US 7,793,137 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications

Abstract

Redundancy of data and/or inline power in a wired data telecommunications network from a pair of network devices via a selection device is provided by communicating redundant signals with each of the pair of network devices and coupling ports of the first network device and corresponding ports of the second network device to paired inputs of the selection device. The selection device operates: 1) under the control of the pair of network devices, one acting as master and one as slave, the master selecting (for each port or for all ports) one of the two paired inputs and causing the selection device to communicate data and/or inline power via a third port of the selection device to a third network device receiving data connectivity and/or inline power from the selection device; or 2) to route two redundant signals to a third network device which then selects one for use.

Claims

1. A method for providing redundancy in a wired data telecommunications network, the method comprising:

coupling a first interface of a first port of a redundancy selection device to a first port of a first network device;

coupling a second interface of the first port of the redundancy selection device to a first port of a second network device;

coupling a third interface of the first port of the redundancy selection device to a first port of a third network device;

coupling data and/or power communicated with the first interface of the first port of the redundancy selection device to communicate data and/or power with the third interface of the first port of the redundancy selection device;

detecting a failure in the flow of data and/or power; and

activating the redundancy selection device in response to said detecting to subsequently couple data and/or power communicated over the second interface of the first port of the redundancy selection device to communicate data and/or power with the third interface.

2. The method of claim 1, wherein:

said detecting detects a failure in the communication of data and/or power between the first port of the first network device and the third network device.

3. The method of claim 1, wherein said detecting takes place at one or more of the first, second and third network devices.

4. The method of claim 1, wherein power for said redundancy selection device is provided as inline power from at least one of the first network device, the second network device and the third network device.

5. The method of claim 1, wherein power for said redundancy selection device is provided as inline power from at least one of said first network device and said second network device.

6. The method of claim 1, further comprising:

notifying a network control point in response to said detecting.

7. The method of claim 6, wherein said notifying is performed using the wired data telecommunications network to send a message from one or more of the first, second and third network devices.

8. The method of claim 6, wherein said notifying is performed wirelessly.

9. The method of claim 6, wherein said notifying is performed using a wireless telecommunications link from the redundancy selection device to a wireless node coupled to the wired data telecommunications network, and from the node to the network control point.

10. The method of claim 1, further comprising:

providing identical data signals (except for the portions of signals intended to represent an address related to the first and second network devices) to the first port of the first network device and to the first port of the second network device.

11. The method of claim 1, wherein:

the first interface includes;

a 1^st node and a 2^nd node adapted to be coupled to a 1^st and a 2^nd conductor of a 1^st pair of conductors;

a 3^rd node and a 4^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 2 pair of conductors;

the second interface includes;

a 5^th node and a 6^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 3^rd pair of conductors;

a 7^th node and an 8^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 4^th pair of conductors; and

the third interface includes;

a 9^th node and a 10^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 5^th pair of conductors;

an 11^th node and a 12^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 6^th pair of conductors; and

wherein

each conductor of said 1^st through 6^th pairs of conductors includes two portions separated by a series-connected diode, each said diode associated with a pair of conductors is oriented to conduct in the same direction, and wherein biasing circuitry is provided to selectively forward-bias the diodes in the pairs of conductors.

12. The method of claim 1, further comprising:

coupling the first network device and the second network device with a data link.

13. The method of claim 12, wherein the data link does not traverse the redundancy selection device.

14. The method of claim 12, wherein the data link traverses the redundancy selection device.

15. The method of claim 14, further comprising:

coupling the first network device and the second network device with an additional data link which does not traverse the redundancy selection device.

46. The method of claim 11, wherein the diodes are forward-biased with the flow of inline power.

49. The method of claim 11, wherein the diodes are forward-biased by means other than the flow of inline power.

52. The method of claim 1, wherein the flow of inline power from the first network device couples the first network device with the third network device.

125. The method of claim 1, further comprising:

detecting a low inline power voltage applied to at least one of the interfaces of the redundancy selection device; and

communicating, responsive to said detecting, from the redundancy selection device to at least one of the first and second network devices the fact that a low inline power voltage has been detected.

16. An apparatus for providing redundancy in a wired data telecommunications network, the apparatus comprising:

means for coupling a first interface of a first port of a redundancy selection device to a first port of a first network device;

means for coupling a second interface of the first port of the redundancy selection device to a first port of a second network device;

means for coupling a third interface of the first port of the redundancy selection device to a first port of a third network device;

means for coupling data and/or power communicated with the first interface of the first port of the redundancy selection device to communicate data and/or power with the third interface of the first port of the redundancy selection device;

means for detecting a failure in the flow of data and/or power; and

means for activating the redundancy selection device responsive to said means for detecting to subsequently couple data and/or power communicated over the second interface of the first port of the redundancy selection device to communicate data and/or power with the third interface.

17. The apparatus of claim 16, wherein:

said means for detecting detects a failure in the communication of data and/or power between the first port of the first network device and the third network device.

18. The apparatus of claim 16, wherein said means for detecting detects at one or more of the first, second and third network devices.

19. The apparatus of claim 16, wherein power for said redundancy selection device is provided as inline power from at least one of the first network device, the second network device and the third network device.

20. The apparatus of claim 16, wherein power for said redundancy selection device is provided as inline power from at least one of said first network device and said second network device.

21. The apparatus of claim 16, further comprising:

means for notifying a network control point responsive to said means for detecting.

22. The apparatus of claim 21, wherein said means for notifying is performed using the wired data telecommunications network to send a message from one or more of the first, second and third network devices.

23. The apparatus of claim 21, wherein said means for notifying is performed wirelessly.

24. The apparatus of claim 21, wherein said means for notifying operates using a wireless telecommunications link from the redundancy selection device to a wireless node coupled to the wired data telecommunications network, and from the node to the network control point.

25. The apparatus of claim 16, further comprising:

means for providing identical data signals (except for the portions of signals intended to represent an address related to the first and second network devices) to the first port of the first network device and to the first port of the second network device.

26. The apparatus of claim 16, wherein:

the first interface includes;

a 1^st node and a 2^nd node adapted to be coupled to a 1^st and a 2^nd conductor of a 1^st pair of conductors;

a 3^rd node and a 4^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 2^nd pair of conductors;

the second interface includes;

a 5^th node and a 6^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 3^rd pair of conductors;

a 7^th node and an 8^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 4^th pair of conductors; and

the third interface includes;

a 9^th node and a 10^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 5^th pair of conductors;

an 11^th node and a 12^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 6^th pair of conductors; and

wherein

each conductor of said 1^st through 6^th pairs of conductors includes two portions separated by a series-connected diode, each said diode associated with a pair of conductors is oriented to conduct in the same direction, and wherein biasing circuitry is provided to selectively forward-bias the diodes in the pairs of conductors.

27. The apparatus of claim 16, further comprising:

means for coupling the first network device and the second network device with a data link.

28. The apparatus of claim 27, wherein the data link does not traverse the redundancy selection device.

29. The apparatus of claim 27, wherein the data link traverses the redundancy selection device.

30. The apparatus of claim 29, further comprising:

means for coupling the first network device and the second network device with an additional data link which does not traverse the redundancy selection device.

47. The apparatus of claim 26, wherein the diodes are forward-biased with the flow of inline power.

50. The apparatus of claim 26, wherein the diodes are forward-biased by means other than the flow of inline power.

53. The apparatus of claim 16, wherein the flow of inline power from the first network device couples the first network device with the third network device.

126. The apparatus of claim 16, wherein the redundancy selection device includes:

means for detecting a low inline power voltage applied to at least one of the interfaces of the redundancy selection device; and

means for communicating with one or both of the first and second network devices the fact that a low inline power voltage has been detected at the redundancy selection device.

31. A system for providing redundancy in a wired data telecommunications network, the system comprising:

circuitry for coupling a first interface of a first port of a redundancy selection device to a first port of a first network device;

circuitry for coupling a second interface of the first port of the redundancy selection device to a first port of a second network device;

circuitry for coupling a third interface of the first port of the redundancy selection device to a first port of a third network device;

circuitry for coupling data and/or power communicated with the first interface of the first port of the redundancy selection device to communicate data and/or power with the third interface of the first port of the redundancy selection device;

circuitry for detecting a failure in the flow of data and/or power; and

circuitry for activating the redundancy selection device responsive to said circuitry for detecting to subsequently couple data and/or power communicated over the second interface of the first port of the redundancy selection device to communicate data and/or power with the third interface.

32. The system of claim 31, wherein:

said circuitry for detecting detects a failure in the communication of data and/or power between the first port of the first network device and the third network device.

33. The system of claim 31, wherein said circuitry for detecting detects at one or more of the first, second and third network devices.

34. The system of claim 31, wherein power for said redundancy selection device is provided as inline power from at least one of the first network device, the second network device and the third network device.

35. The system of claim 31, wherein power for said redundancy selection device is provided as inline power from at least one of said first network device and said second network device.

36. The system of claim 31, further comprising:

circuitry for notifying a network control point responsive to said circuitry for detecting.

37. The system of claim 36, wherein said circuitry for notifying utilizes the wired data telecommunications network to send a message from one or more of the first, second and third network devices.

38. The system of claim 36, wherein said circuitry for notifying utilizes wireless communications.

39. The system of claim 36, wherein said circuitry for notifying utilizes a wireless telecommunications link from the redundancy selection device to a wireless node coupled to the wired data telecommunications network, and from the node to the network control point.

40. The system of claim 31, further comprising:

circuitry for providing identical data signals (except for the portions of signals intended to represent an address related to the first and second network devices) to the first port of the first network device and to the first port of the second network device.

41. The system of claim 31, wherein:

the first interface includes;

a 1^st node and a 2^nd node adapted to be coupled to a 1^st and a 2^nd conductor of a 1^st pair of conductors;

a 3^nd node and a 4^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 2^nd pair of conductors;

the second interface includes;

a 5^th node and a 6^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 3^rd pair of conductors;

a 7^th node and an 8^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 4^th pair of conductors; and

the third interface includes;

a 9^th node and a 10^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 5^th pair of conductors;

an 11^th node and a 12^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 6^th pair of conductors; and

wherein

each conductor of said 1^st through 6^th pairs of conductors includes two portions separated by a series-connected diode, each said diode associated with a pair of conductors is oriented to conduct in the same direction, and wherein biasing circuitry is provided to selectively forward-bias the diodes in the pairs of conductors.

42. The system of claim 31, further comprising:

circuitry for coupling the first network device and the second network device with a data link.

43. The system of claim 42, wherein the data link does not traverse the redundancy selection device.

44. The system of claim 42, wherein the data link traverses the redundancy selection device.

45. The system of claim 44, further comprising:

circuitry for coupling the first network device and the second network device with an additional data link which does not traverse the redundancy selection device.

48. The system of claim 41, wherein the diodes are forward-biased with the flow of inline power.

51. The system of claim 41, wherein the diodes are forward-biased by means other than the flow of inline power.

54. The system of claim 31, wherein the flow of inline power from the first network device couples the first network device with the third network device.

55. A method for providing redundancy in a wired data telecommunications network, the method comprising:

coupling a first interface of a first port of a redundancy selection device to a first port of a first network device;

coupling a second interface of the first port of the redundancy selection device to a first port of a second network device;

coupling a third interface of the first port of the redundancy selection device to a first port of a third network device;

coupling data and/or power communicated over the first interface of the first port of the redundancy selection device to communicate data and/or power to a third interface of the first port of the redundancy selection device;

wherein

the first interface includes;

a 1^st node and a 2^nd node adapted to be coupled to a 1^st and a 2^nd conductor of a 1^st pair of conductors;

a 3^rd node and a 4^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 2^nd pair of conductors;

the second interface includes;

a 5^th node and a 6^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 3^rd pair of conductors;

a 7^th node and an 8^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 4^th pair of conductors;

the third interface includes;

a 9^th node and a 10^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 5^th pair of conductors;

an 11^th node and a 12^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 6^th pair of conductors.

a 13^th node and a 14^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 7^th pair of conductors;

a 15^th node and a 16^th node adapted to be coupled to a 1^st and a 2^nd conductor of an 8^th pair of conductors and wherein;

the 5^th and 6^th pairs of conductors are coupled through the redundancy selection device to the 1^st and 2^nd pairs of conductors, respectively, and

the 7^th and 8^th pairs of conductors are coupled through the redundancy selection device to the 3^rd and 4^th pairs of conductors, respectively.

56. The method of claim 55, wherein:

the first interface further includes;

a 17^th node and an 18^th node adapted to be coupled to a first and a second conductor of a 9^th pair of conductors;

a 19^th node and a 20^th node adapted to be coupled to a first and a second conductor of a 10^th pair of conductors;

the second interface further includes;

a 21^st node and a 22^nd node adapted to be coupled to a first and a second conductor of an 11^th pair of conductors;

a 23^rd node and a 24^th node adapted to be coupled to a first and a second conductor of a 12^th pair of conductors; and

;

the 9^th and 10^th pairs of conductors are coupled through the redundancy selection device to the 11^th and 12^th pairs of conductors, respectively.

57. The method of claim 56, further comprising:

providing data telecommunications between the first network device and the second network device via the 9^th, 10^th, 11^th and 12^th pairs of conductors through the redundancy selection device.

58. The method of claim 55 further comprising:

detecting at the third network device a fault in data and/or power communicated with the first network device through the redundancy selection device; and

selecting at the third network device, responsive to said detecting, to communicate data and/or power with the second network device.

59. The method of claim 58 wherein:

said detecting detects a failure in the communication of data and/or power between the first port of the first network device and the first port of the third network device.

60. The method of claim 58, wherein said detecting takes place at the third network device.

61. The method of claim 58, wherein power for said redundancy selection device is provided as inline power from at least one of the first network device, the second network device and the third network device.

62. The method of claim 58, wherein power for said redundancy selection device is provided as inline power from at least one of said first network device and said second network device.

63. The method of claim 58, further comprising:

notifying a network control point in response to said detecting.

64. The method of claim 63, wherein said notifying is performed using the wired data telecommunications network to send a message from the redundancy selection device through at least one of the first data telecommunications device and the second data telecommunications device.

65. The method of claim 63, wherein said notifying is performed wirelessly.

66. The method of claim 63, wherein said notifying is performed using a wireless telecommunications link from the redundancy selection device to a wireless node coupled to the wired data telecommunications network, and from the node to the network control point.

67. The method of claim 58, further comprising:

providing identical data signals (except for the portions of signals intended to represent an address related to the first and second network devices) to the first port of the first network device and to the first port of the second network device.

68. The method of claim 58, wherein:

each conductor of said 1^st through 6^th pairs of conductors includes two portions separated by a series-connected diode, and each said diode associated with a pair of conductors is oriented to conduct in the same direction, and further comprising;

biasing circuitry to selectively forward bias the diodes in the pairs of conductors.

69. The method of claim 58, further comprising:

coupling the first network device and the second network device with a data link.

70. The method of claim 69, wherein the data link does not traverse the redundancy selection device.

71. The method of claim 69, wherein the data link traverses the redundancy selection device.

72. The method of claim 71, further comprising:

coupling the first network device and the second network device with an additional data link which does not traverse the redundancy selection device.

73. An apparatus for providing redundancy in a wired data telecommunications network, the apparatus comprising:

means for coupling a first interface of a first port of a redundancy selection device to a first port of a first network device;

means for coupling a second interface of the first port of the redundancy selection device to a first port of a second network device;

means for coupling data and/or power communicated over the first interface of the first port of the redundancy selection device to communicate data and/or power to a third interface of the first port of the redundancy selection device;

wherein

the first interface includes;

a 1^st node and a 2^nd node adapted to be coupled to a 1^st and a 2^nd conductor of a 1^st pair of conductors;

a 3^nd node and a 4^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 2^nd pair of conductors;

the second interface includes;

a 5^th node and a 6^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 3^rd pair of conductors;

a 7^th node and an 8^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 4^th pair of conductors;

the third interface includes;

a 9^th node and a 10^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 5^th pair of conductors;

an 11^th node and a 12^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 6^th pair of conductors.

a 13^th node and a 14^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 7^th pair of conductors;

a 15^th node and a 16^th node adapted to be coupled to a 1^st and a 2^nd conductor of an 8^th pair of conductors and wherein;

the 5^th and 6^th pairs of conductors are coupled through the redundancy selection device to the 1^st and 2^nd pairs of conductors, respectively, and

the 7^th and 8^th pairs of conductors are coupled through the redundancy selection device to the 3^rd and 4^th pairs of conductors, respectively.

74. The apparatus of claim 73, wherein:

the first interface further includes;

a 17^th node and an 18^th node adapted to be coupled to a first and a second conductor of a 9^th pair of conductors;

a 19^th node and a 20^th node adapted to be coupled to a first and a second conductor of a 10^th pair of conductors;

the second interface further includes;

a 21^st node and a 22^nd node adapted to be coupled to a first and a second conductor of an 11^th pair of conductors;

a 23^rd node and a 24^th node adapted to be coupled to a first and a second conductor of a 12^th pair of conductors; and

;

the 9^th and 10^th pairs of conductors are coupled through the redundancy selection device to the 11^th and 12^th pairs of conductors, respectively.

75. The apparatus of claim 74, further comprising:

means for providing data telecommunications between the first network device and the second network device via the 9^th, 10^th, 11^th and 12^th pairs of conductors through the redundancy selection device.

76. The apparatus of claim 75 further comprising:

means for detecting at the third network device a fault in data and/or power communicated with the first network device through the redundancy selection device; and

means for selecting at the third network device, responsive to said means for detecting, to communicate data and/or power with the second network device.

77. The apparatus of claim 76, wherein:

said means for detecting detects a failure in the communication of data and/or power between the first port of the third network device and the first port of the first network device.

78. The apparatus of claim 76, wherein said means for detecting is disposed at the third network device.

79. The apparatus of claim 76, wherein power for said redundancy selection device is provided as inline power from at least one of the first network device, the second network device and the third network device.

80. The apparatus of claim 76, wherein power for said redundancy selection device is provided as inline power from at least one of said first network device and said second network device.

81. The apparatus of claim 76, further comprising:

means for notifying a network control point responsive to said means for detecting.

82. The apparatus of claim 81, wherein said means for notifying utilizes the wired data telecommunications network to send a message from the redundancy selection device through at least one of the first data telecommunications device and the second data telecommunications device.

83. The apparatus of claim 81, wherein said means for notifying utilizes a wireless telecommunications device.

84. The apparatus of claim 81, wherein said means for notifying utilizes a wireless telecommunications link from the redundancy selection device to a wireless node coupled to the wired data telecommunications network, and from the node to the network control point.

85. The apparatus of claim 76, further comprising:

means for providing identical data signals (except for the portions of signals intended to represent an address related to the first and second network devices) to the first port of the first network device and to the first port of the second network device.

86. The apparatus of claim 76, wherein:

each conductor of said 1^st through 6^th pairs of conductors includes two portions separated by a series-connected diode, and each said diode associated with a pair of conductors is oriented to conduct in the same direction, and further comprising

means for biasing to selectively forward bias the diodes in the pairs of conductors.

87. The apparatus of claim 76, further comprising:

means for coupling the first network device and the second network device with a data link.

88. The apparatus of claim 87, wherein the data link does not traverse the redundancy selection device.

89. The apparatus of claim 87, wherein the data link traverses the redundancy selection device.

90. The apparatus of claim 89, further comprising:

means for coupling the first network device and the second network device with an additional data link which does not traverse the redundancy selection device.

91. A system for providing redundancy in a wired data telecommunications network, the method comprising:

circuitry for coupling a first interface of a first port of a redundancy selection device to a first port of a first network device;

circuitry for coupling a second interface of the first port of the redundancy selection device to a first port of a second network device;

circuitry for coupling data and/or power communicated over the first interface of the first port of the redundancy selection device to communicate data and/or power to a third interface of the first port of the redundancy selection device;

wherein

the first interface includes;

a 1^st node and a 2^nd node adapted to be coupled to a 1^st and a 2^nd conductor of a 1^st pair of conductors;

a 3^rd node and a 4^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 2^nd pair of conductors;

the second interface includes;

a 5^th node and a 6^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 3^rd pair of conductors;

a 7^th node and an 8^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 4^th pair of conductors; and

the third interface includes;

a 9^th node and a 10^th node adapted to be coupled to a 11^st and a 2^nd conductor of a 5^th pair of conductors;

an 11^th node and a 12^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 6^th pair of conductors;

a 13^th node and a 14^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 7^th pair of conductors;

a 15^th node and a 16^th node adapted to be coupled to a 1^st and a 2^nd conductor of an 8^th pair of conductors, and wherein;

the 5^th and 6^th pairs of conductors are coupled through the redundancy selection device to the 1^st and 2^nd pairs of conductors, respectively, and

the 7^th and 8^th pairs of conductors are coupled through the redundancy selection device to the 3^rd and 4^th pairs of conductors, respectively.

92. The system of claim 91, wherein:

the first interface further includes;

a 17^th node and an 18^th node adapted to be coupled to a first and a second conductor of a 9^th pair of conductors;

a 19^th node and a 20^th node adapted to be coupled to a first and a second conductor of a 10^th pair of conductors;

the second interface further includes;

a 21^st node and a 22^nd node adapted to be coupled to a first and a second conductor of an 11^th pair of conductors;

a 23^rd node and a 24^th node adapted to be coupled to a first and a second conductor of a 12^th pair of conductors; and

;

the 9^th and 10^th pairs of conductors are coupled through the redundancy selection device to the 11^th and 12^th pairs of conductors, respectively.

93. The system of claim 92, further comprising:

circuitry for providing data telecommunications between the first network device and the second network device via the 9^th, 10^th, 11^th and 12^th pairs of conductors through the redundancy selection device.

94. The system of claim 91 further comprising:

circuitry for detecting at the third network device a fault in data and/or power communicated with the first network device through the redundancy selection device; and

selecting at the third network device, responsive to said detecting, to communicate data and/or power with the second network device.

95. The system of claim 94, wherein:

said circuitry for detecting detects a failure in the communication of data and/or power between the first port of the first network device and the first port of the third network device.

96. The system of claim 94, wherein said circuitry for detecting is disposed at the third network device.

97. The system of claim 94, wherein power for said redundancy selection device is provided as inline power from at least one of the first network device, the second network device and the third network device.

98. The system of claim 94, wherein power for said redundancy selection device is provided as inline power from at least one of said first network device and said second network device.

99. The system of claim 94, further comprising:

circuitry for notifying a network control point responsive to said circuitry for detecting.

100. The system of claim 99, wherein said circuitry for notifying utilizes the wired data telecommunications network to send a message from the redundancy selection device through at least one of the first data telecommunications device and the second data telecommunications device.

101. The system of claim 99, wherein said circuitry for notifying utilizes a wireless telecommunications device.

102. The system of claim 99, wherein said circuitry for notifying utilizes a wireless telecommunications link from the redundancy selection device to a wireless node coupled to the wired data telecommunications network, and from the node to the network control point.

103. The system of claim 94, further comprising:

circuitry for providing identical data signals (except for the portions of signals intended to represent an address related to the first and second network devices) to the first port of the first network device and to the first port of the second network device.

104. The system of claim 94, wherein:

each conductor of said 1^st through 6^th pairs of conductors includes two portions separated by a series-connected diode, and each said diode associated with a pair of conductors is oriented to conduct in the same direction, and further comprising

circuitry for biasing to selectively forward bias the diodes in the pairs of conductors.

105. The system of claim 94, further comprising:

circuitry for coupling the first network device and the second network device with a data link.

106. The system of claim 105, wherein the data link does not traverse the redundancy selection device.

107. The system of claim 105, wherein the data link traverses the redundancy selection device.

108. The system of claim 107, further comprising:

circuitry for coupling the first network device and the second network device with an additional data link which does not traverse the redundancy selection device.

109. A redundancy selection device adapted to be coupled to at least a first network device, a second network device and a third network device, the redundancy selection device comprising:

a redundancy selection circuit having at least a first port, said port having a first interface for communicating with the first network device and a second interface for communicating with the second network device, and a third interface for communicating with the third network device; and

a controller operable to;

set an initial mode of operation for the redundancy selection device wherein the redundancy selection device communicates signals between the third interface of the first port of the redundancy selection device and the first interface of the first port of the redundancy selection device;

detect a failure in inline power and/or data communicated with the first interface of the first port of the redundancy selection device; and

responsive to said detection of a failure, set a subsequent mode of operation for the redundancy selection device wherein the redundancy selection device communicates signals between the third interface of the first port of the redundancy selection device and the second interface of the first port of the redundancy selection device.

110. The redundancy selection device of claim 109, wherein:

the first interface includes;

a 1^st node and a 2^nd node adapted to be coupled to a 1^st and a 2^nd conductor of a 1^st pair of conductors;

a 3^rd node and a 4^th node adapted to be coupled to a 1^st and a 2 conductor of a 2^nd pair of conductors;

the second interface includes;

a 5^th node and a 6^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 3^rd pair of conductors;

a 7^th node and an 8^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 4^th pair of conductors;

the third interface includes;

a 9^th node and a 10^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 5^th pair of conductors;

an 11^th node and a 12^th node adapted to be coupled to a 1^st and a 2^nd conductor of a 6^th pair of conductors; and

wherein

each conductor of said 1^st through 6^th pairs of conductors includes two portions separated by a series-connected diode, each said diode associated with a pair of conductors is oriented to conduct in the same direction, and further comprising biasing circuitry to selectively forward bias the diodes in the pairs of conductors.

111. A method for providing redundancy in a wired data telecommunications network, the method comprising:

coupling a first interface of a first port of a redundancy selection device to a first port of a first network device, the first interface providing four pairs of connectivity between the first port of the first network device and the first port of the redundancy selection device;

coupling a second interface of the first port of the redundancy selection device to a first port of a second network device, the second interface providing two pairs of connectivity between the first port of the second network device and the first port of the redundancy selection device;

coupling a third interface of a first port of a redundancy selection device to a first port of a third network device, the third interface providing four pairs of connectivity between the first port of the third network device and the third port of the redundancy selection device;

coupling data and/or power communicated with the first interface of the first port of the redundancy selection device to communicate data and/or power with a third interface of the first port of the redundancy selection device;

detecting a fault in the flow of data and/or power through the first port of the first network device; and

activating the redundancy selection device in response to said detecting to subsequently;

(1) provide two pairs of connectivity between the first port of the third network device and the first port of the redundancy selection device; and

(2) provide two pairs of connectivity between the first port of the third network device and the first port of the second network device.

112. An apparatus for providing redundancy in a wired data telecommunications network, the apparatus comprising:

means for coupling a first interface of a first port of a redundancy selection device to a first port of a first network device, the first interface providing four pairs of connectivity between the first port of the first network device and the first port of the redundancy selection device;

means for coupling a second interface of the first port of the redundancy selection device to a first port of a second network device, the second interface providing two pairs of connectivity between the first port of the second network device and the first port of the redundancy selection device;

means for coupling a third interface of a first port of a redundancy selection device to a first port of a third network device, the third interface providing four pairs of connectivity between the first port of the third network device and the third port of the redundancy selection device;

means for coupling data and/or power communicated with the first interface of the first port of the redundancy selection device to communicate data and/or power with a third interface of the first port of the redundancy selection device;

means for detecting a fault in the flow of data and/or power through the first port of the first network device; and

means for activating the redundancy selection device in response to said detecting to subsequently;

(1) provide two pairs of connectivity between the first port of the third network device and the first port of the redundancy selection device; and

(2) provide two pairs of connectivity between the first port of the third network device and the first port of the second network device.

113. A system for providing redundancy in a wired data telecommunications network, the system comprising:

circuitry for coupling a first interface of a first port of a redundancy selection device to a first port of a first network device, the first interface providing four pairs of connectivity between the first port of the first network device and the first port of the redundancy selection device;

circuitry for coupling a second interface of the first port of the redundancy selection device to a first port of a second network device, the second interface providing two pairs of connectivity between the first port of the second network device and the first port of the redundancy selection device;

circuitry for coupling a third interface of a first port of a redundancy selection device to a first port of a third network device, the third interface providing four pairs of connectivity between the first port of the third network device and the third port of the redundancy selection device;

circuitry for coupling data and/or power communicated with the first interface of the first port of the redundancy selection device to communicate data and/or power with a third interface of the first port of the redundancy selection device;

circuitry for detecting a fault in the flow of data and/or power through the first port of the first network device; and

circuitry for activating the redundancy selection device in response to said detecting to subsequently;

(1) provide two pairs of connectivity between the first port of the third network device and the first port of the redundancy selection device; and

(2) provide two pairs of connectivity between the first port of the third network device and the first port of the second network device.

114. A network segment of a wired data telecommunications network, the network segment comprising:

a first network device having at least a first local port and at least a first uplink port;

a second network device having at least a first local port and at least a first uplink port;

a third network device having at least a first port; and

a redundancy selection device (RSD) having at least a first port with a first, second and third interface, the first interface of the RSD coupled to the first local port of the first network device, the second interface of the RSD coupled to the first local port of the second network device, and the third interface of the RSD coupled to the first port of the third network device,

wherein data and/or power are communicated between the third network device and the first and/or second network device through the RSD; and

wherein at least two pairs of conductors are used to couple data and/or power from the first network device to the third network device while at least one first pair of conductors is used to couple data transmitted from the third network device to the second network device and at least one second pair of conductors is used to couple data transmitted from said first network device to said second network device.

115. The network segment of claim 114, wherein said at least one first pair of conductors and said at least one second pair of conductors each include at least two pairs of conductors.

116. A method for testing a network segment, the segment comprising a first network device having a first port, a second network device having a first port and a third network device having a first port, the first port of the first network device coupled to a first interface of a first port of a redundancy selection device, the first port of the second network device coupled to a second interface of the first port of the redundancy selection device, and the first port of the third network device coupled to a third interface of the first port of the redundancy selection device, the method comprising:

sending a predetermined routable test packet from the first network device to the third network device through the first port of the redundancy selection device;

receiving the test packet at the third network device;

modifying the test packet in a predetermined manner into a modified test packet at the third network device;

sending the modified test packet from the third network device through the first port of the redundancy selection device;

receiving the modified test packet at at least the first port of the second network device;

inspecting the modified test packet at the second network device; and

determining the operational status of the third network device at the second network device in response to said inspecting.

117. The method of claim 116, further comprising:

monitoring said sending of the test packet from the first network device to the third network device at said second network device; and

determining a failure in the communications link between the first network device and the third network device in response to not receiving the modified test packet from the third network device within a predetermined period of time of said sending.

118. A method for testing a network segment, the segment comprising a first network device having a first port, a second network device having a first port and a third network device having a first port, the first port of the first network device coupled to a first interface of a first port of a redundancy selection device, the first port of the second network device coupled to a second interface of the first port of the redundancy selection device, and the first port of the third network device coupled to a third interface of the first port of the redundancy selection device, the method comprising:

sending a predetermined routable test packet from one of the first, second and third network devices (originating device) to another of the first, second and third network devices (tested device) through the first port of the redundancy selection device;

receiving the test packet at the tested device;

modifying the test packet in a predetermined manner into a modified test packet at the tested device;

sending the modified test packet from the tested device through the first port of the redundancy selection device;

receiving the modified test packet at the originating device;

inspecting the modified test packet at the originating device; and

determining an operational status of the tested device at the originating device in response to said inspecting.

119. The method of claim 118, further comprising:

determining that the tested device and/or its connectivity to the originating device has failed if said receiving is not accomplished within a predetermined amount of time.

120. A method for testing a network segment, the segment comprising a first network device original acting as a master having a first port, a second network device originally acting as a slave having a first port and a third network device having a first port, the first port of the first network device coupled to a first interface of a first port of a redundancy selection device, the first port of the second network device coupled to a second interface of the first port of the redundancy selection device, and the first port of the third network device coupled to a third interface of the first port of the redundancy selection device, the method comprising:

sending a predetermined routable test packet from the first network device to the third network device through the first port of the redundancy selection device;

receiving the test packet at the third network device;

modifying the test packet in a predetermined manner into a modified test packet at the third network device;

sending the modified test packet from the third network device through the first port of the redundancy selection device;

receiving the modified test packet at at least the first port of the second network device;

inspecting the modified test packet at the second network device; and

having the second network device take over as master from the first network device in response to said inspecting.

121. The method of claim 120, further comprising:

monitoring said sending of the test packet from the first network device to the third network device at said second network device; and

having the second network device take over as master from the first network device in response to not receiving the modified test packet from the third network device within a predetermined period of time of said sending.

122. A powered device coupled to receive inline power, comprising:

a threshold detection circuit monitoring the inline power voltage;

a switch controlled by the threshold detection circuit;

a load circuit coupled through the switch to receive power when the switch is closed;

the threshold detection circuit arranged to close the switch when the inline power voltage is within a first range of voltage levels and to open the switch when the inline power voltage exceeds said first range of voltage levels.

123. The powered device of claim 122, wherein:

the first range of voltage levels is less than about 5 volts DC.

124. The powered device of claim 123, wherein:

the load circuit comprises circuitry for forward-biasing signal diodes.

127. A method for communicating among a first network device, a second network device and a third network device in a network segment, the segment comprising a first network device having a first port, a second network device having a first port and a third network device having a first port, the first port of the first network device coupled to a first interface of a first port of a redundancy selection device, the first port of the second network device coupled to a second interface of the first port of the redundancy selection device, and the first port of the third network device coupled to a third interface of the first port of the redundancy selection device, the method comprising:

coupling the first, second and third interfaces together on a conductor-by-conductor basis within the redundancy selection device;

initiating a communication at the first network device; and

receiving the communication through the redundancy selection device at both said second and said third network devices.

128. A power sourcing equipment device (PSE), comprising:

means for detecting a first mode of operation of a powered device (PD) identity network, the identity network operating in the first mode to sink DC current when it is supplied with less than about 5 VDC of inline power; and

means for detecting a second mode of operation of the PD identity network, the identity network operating in the second mode to act like a fixed resistance that is much higher than 25 k ohms when it is supplied with more than about 5 VDC of inline power.

129. The device of claim 128, further comprising:

means for detecting an IEEE 802.3af inline power identity network.

130. A device, comprising:

means for operating in a first mode of operation as a powered device (PD) accepting inline power from a power sourcing equipment (PSE) device; and

means for operating in a second mode of operation as a PSE device, providing inline power to a PD;

wherein the device, when operating in said first mode of operation adapted to extract inline power from two pairs of twisted-pair conductors through a high-impedance AC (alternating current) coupling and when in said second mode of operation adapted to inject inline power to the two pairs of conductors through the high-impedance AC coupling.

131. A method for communicating among a first network device, a second network device and a third network device in a network segment, the segment comprising a first network device having a first port, a second network device having a first port and a third network device having a first port, the first port of the first network device coupled to a first interface of a first port of a redundancy selection device, the first port of the second network device coupled to a second interface of the first port of the redundancy selection device, and the first port of the third network device coupled to a third interface of the first port of the redundancy selection device, the method comprising:

providing inline power and data from the first interface to the third interface;

providing attenuated inline power and data to the second interface;

using the inline power provided over the first interface to forward-bias signal diodes in the conductors coupling the first and third interfaces; and

using attenuated inline power provided over the first interface to forward-bias signal diodes in the conductors coupling the first and second interfaces.