Inline power-based common mode communications in a wired data telecommunications network

• US 20060082220A1
• Filed: 10/07/2004
• Published: 04/20/2006
• 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: Schindler, Frederick R., Diab, Wael William, Karam, Roger A.
• Granted Patent: US 8,300,666 B2
• Time in Patent Office: Days
• US Class Current: 307/4
• CPC Class Codes: H02J 13/00009 using pulsed signals
• CPC Class Codes: H02J 13/0001 using modification of a parameter of the network power signal
• CPC Class Codes: H02J 13/00012 using an auxiliary transmission line
• CPC Class Codes: H02J 13/00018 using phone lines

Abstract

Communications over a wired data telecommunications network between and among power sourcing equipment (PSE), powered devices (PDs), and the like, take place over the wired medium by modulating an inline power signal. Any suitable communications protocol may be used and any suitable modulation scheme can be used. Examples of information to be communicated include: changing power requirements or capabilities (higher or lower) and acknowledgements thereof (permitting finer power class gradation than available under existing standards); sensor data; wireless data converted to wired data; status signaling, and the like. Such communications may be used for a number of purposes including supporting redundant provision of services over a network.

Claims

1. A method for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the method comprising:

biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

voltage modulating the difference voltage with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

2. The method of claim 1, wherein during said biasing the difference voltage exceeds 20 Volts.

3. The method of claim 1, wherein said modulating takes place while at least one of the first station and the second station is powered by the difference voltage.

4. The method of claim 3, wherein during said biasing the difference voltage exceeds 20 Volts.

107. The method of claim 1, wherein the message comprises a voltage measurement of the difference voltage.

116. The method of claim 1, wherein the second station has a predetermined unique address value associate with it and further comprising:

selecting the second station from among a plurality of stations based upon its unique address value.

5. A method for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the method comprising:

biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

current modulating a current flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

6. The method of claim 5, wherein during said biasing the difference voltage exceeds 20 Volts.

7. The method of claim 5, wherein said modulating takes place while at least one of the first station and the second station is powered by the difference voltage.

8. The method of claim 7, wherein during said biasing the difference voltage exceeds 20 Volts.

108. The method of claim 6, wherein the message comprises a voltage measurement of the difference voltage.

117. The method of claim 5, wherein the second station has a predetermined unique address value associate with it and further comprising:

selecting the second station from among a plurality of stations based upon its unique address value.

9. An apparatus for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the apparatus comprising:

means for biasing the first pair of conductors with one direct current (DC) voltage level;

means for biasing the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

means for voltage modulating the difference voltage with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

10. The apparatus of claim 9, wherein said biasing means are adapted to cause the difference voltage to exceed 20 Volts in operation.

11. The apparatus of claim 9, wherein said modulating means is operable while at least one of the first station and the second station is powered by the difference voltage.

12. The method of claim 11, wherein said biasing means are adapted to cause the difference voltage to exceed 20 Volts in operation.

109. The apparatus of claim 9, further comprising:

means disposed at the first device for measuring a magnitude of the voltage difference and including it in the message.

118. The apparatus of claim 9, wherein the second station has a unique predetermined address value associated with it and further comprising:

means for selecting the second station from among a plurality of stations based upon its unique address value.

13. An apparatus for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the apparatus comprising:

means for biasing the first pair of conductors with one direct current (DC) voltage level;

means for biasing the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

means for current modulating a current flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

14. The apparatus of claim 13, wherein said biasing means are adapted to cause the difference voltage to exceed 20 Volts in operation.

15. The apparatus of claim 13, wherein the modulating means is operable while at least one of the first station and the second station is powered by the difference voltage.

16. The method of claim 15, wherein said biasing means are adapted to cause the difference voltage to exceed 20 Volts in operation.

110. The apparatus of claim 13, further comprising:

means disposed at the first device for measuring a magnitude of the voltage difference and including it in the message.

119. The apparatus of claim 13, wherein the second station has a unique predetermined address value associated with it and further comprising:

means for selecting the second station from among a plurality of stations based upon its unique address value.

17. A system for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the system comprising:

circuitry for biasing the first pair of conductors with one direct current (DC) voltage level;

circuitry for biasing the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

circuitry for voltage modulating the difference voltage with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

18. The system of claim 17, wherein said biasing circuitries are adapted to cause the difference voltage to exceed 20 Volts in operation.

19. The system of claim 17, wherein said circuitry for modulating is operable while at least one of the first station and the second station is powered by the difference voltage.

20. The system of claim 19, wherein said biasing circuitries are adapted to cause the difference voltage to exceed 20 Volts in operation.

111. The system of claim 17, further comprising:

circuitry at the first station for measuring a magnitude of the voltage difference and including it in the message.

120. The system of claim 17, wherein the second station has a unique predetermined address value associated with it and further comprising:

circuitry for selecting the second station from among a plurality of stations based upon its unique address value.

21. A system for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the system comprising:

circuitry for biasing the first pair of conductors with one direct current (DC) voltage level;

circuitry for biasing the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

circuitry for current modulating a current flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

22. The system of claim 21, wherein said biasing circuitries are adapted to cause the difference voltage to exceed 20 Volts in operation.

23. The system of claim 21, wherein said circuitry for modulating is operable while at least one of the first station and the second station is powered by the difference voltage.

24. The system of claim 23, wherein said biasing circuitries are adapted to cause the difference voltage to exceed 20 Volts in operation.

112. The system of claim 21, further comprising:

circuitry at the first station for measuring a magnitude of the voltage difference and including it in the message.

121. The system of claim 21, wherein the second station has a unique predetermined address value associated with it and further comprising:

circuitry for selecting the second station from among a plurality of stations based upon its unique address value.

25. A system for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the system comprising:

a first biaser for biasing the first pair of conductors with one direct current (DC) voltage level;

a second biaser for biasing the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

a modulator for voltage modulating the difference voltage with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

26. The system of claim 25, wherein said biasers are adapted to cause the difference voltage to exceed 20 Volts in operation.

27. The system of claim 25, wherein said modulator is operable while at least one of the first station and the second station is powered by the difference voltage.

28. The system of claim 27, wherein said biasers are adapted to cause the difference voltage to exceed 20 Volts in operation.

113. The system of claim 25, further comprising:

a voltage measurer for measuring a magnitude of the voltage difference;

wherein the message includes the magnitude.

29. A system for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station comprising power sourcing equipment (PSE) or a powered device (PD) or a power tap device (PT), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the system comprising:

a first biaser for biasing the first pair of conductors with one direct current (DC) voltage level;

a second biaser for biasing the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

a modulator for current modulating a current flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

30. The system of claim 29, wherein said biasers are adapted to cause the difference voltage to exceed 20 Volts in operation.

31. The system of claim 29, wherein said modulator is operable while at least one of the first station and the second station is powered by the difference voltage.

32. The system of claim 31, wherein said biasers are adapted to cause the difference voltage to exceed 20 Volts in operation.

114. The system of claim 29, further comprising:

a voltage measurer for measuring a magnitude of the voltage difference;

wherein the message includes the magnitude.

33. A method for communicating a message from a powered device (PD) to power sourcing equipment (PSE) in a wired data telecommunications network, the method comprising:

performing a PD detection and classification to verify that the PD may be supplied with inline power from the PSE;

responsive to said performing, establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

current modulating the power at the PD with a predetermined communications protocol to communicate the message from the PD to the PSE.

34. The method of claim 33, wherein:

the message includes a request for a different minimum level of power from the PSE to the PD, and further comprising;

responsive to said current modulating, providing the different minimum level of power from the PSE to the PD.

35. The method of claim 34, wherein:

the PD is a voice over internet protocol telephone and the PSE is a switch.

36. An apparatus for communicating a message from a powered device (PD) to power sourcing equipment (PSE) in a wired data telecommunications network, the apparatus comprising:

means for performing a PD detection and classification to verify that the PD may be supplied with inline power from the PSE;

means responsive to said means for performing, for establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

means for current modulating the power at the PD with a predetermined communications protocol to communicate the message from the PD to the PSE.

37. The apparatus of claim 36, wherein:

the message includes a request for a different minimum level of power from the PSE to the PD, and further comprising;

means, responsive to said current modulating, for providing the different minimum level of power from the PSE to the PD.

38. The apparatus of claim 37, wherein:

the PD is a voice over internet protocol telephone and the PSE is a switch.

39. A system for communicating a message from a powered device (PD) to power sourcing equipment (PSE) in a wired data telecommunications network, the system comprising:

circuitry for performing a PD detection and classification to verify that the PD may be supplied with inline power from the PSE;

circuitry responsive to said circuitry for performing, for establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

circuitry for current modulating the power at the PD with a predetermined communications protocol to communicate the message from the PD to the PSE.

40. The system of claim 39, wherein:

the message includes a request for a different minimum level of power from the PSE to the PD, and further comprising;

circuitry, responsive to said current modulating, for providing the different minimum level of power from the PSE to the PD.

41. The system of claim 40, wherein:

the PD is a voice over internet protocol telephone and the PSE is a switch.

91. The system of claim 39, wherein:

the wired data telecommunications network includes a first pair of conductors for performing at least the function of transmitting data from the PD to the PSE and the circuitry for current modulating will remain operable to communicate the message from the PD to the PSE even if one conductor of said first pair of conductors is open.

93. The system of claim 39, wherein:

the wired data telecommunications network includes a first pair of conductors for performing at least the function of transmitting data from the PD to the PSE and the circuitry for current modulating will remain operable to communicate the message from the PD to the PSE even if both conductors of said first pair of conductors are shorted together.

42. A method for communicating a message from power sourcing equipment (PSE) to a powered device (PD) in a wired data telecommunications network, the method comprising:

performing a PD detection and classification to verify that the PD may be supplied with inline power from the PSE;

responsive to said performing, establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

voltage modulating the power at the PSE with a predetermined communications protocol to communicate the message from the PSE to the PD.

43. The method of claim 42, wherein:

the message includes a confirmation of a request for a different minimum level of power from the PSE to the PD, and further comprising;

responsive to said voltage modulating, providing the different minimum level of power from the PSE to the PD.

44. The method of claim 43, wherein:

the PD is a voice over internet protocol telephone and the PSE is a switch.

45. An apparatus for communicating a message from power sourcing equipment (PSE) to a powered device (PD) in a wired data telecommunications network, the apparatus comprising:

means for performing a PD detection and classification to verify that the PD may be supplied with inline power from the PSE;

means responsive to said means for performing, for establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

means for voltage modulating the power at the PSE with a predetermined communications protocol to communicate the message from the PSE to the PD.

46. The apparatus of claim 45, wherein:

the message includes a confirmation of a request for a different minimum level of power from the PSE to the PD, and further comprising;

means, responsive to said voltage modulating, for providing the different minimum level of power from the PSE to the PD.

47. The apparatus of claim 46, wherein:

the PD is a voice over internet protocol telephone and the PSE is a switch.

48. A system for communicating a message from power sourcing equipment (PSE) to a powered device (PD) in a wired data telecommunications network, the system comprising:

circuitry for performing a PD detection and classification to verify that the PD may be supplied with inline power from the PSE;

circuitry responsive to said circuitry for performing, for establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

circuitry for voltage modulating the power at the PSE with a predetermined communications protocol to communicate the message from the PSE to the PD.

49. The system of claim 48, wherein:

the message includes a confirmation of a request for a different minimum level of power from the PSE to the PD, and further comprising;

circuitry, responsive to said voltage modulating, for providing the different minimum level of power from the PSE to the PD.

50. The system of claim 49, wherein:

the PD is a voice over internet protocol telephone and the PSE is a switch.

92. The system of claim 48, wherein:

the wired data telecommunications network includes a first pair of conductors for performing at least the function of transmitting data from the PSE to the PD and the circuitry for voltage modulating will remain operable to communicate the message from the PSE to the PD even if one conductor of said first pair of conductors is open.

94. The system of claim 48, wherein:

the wired data telecommunications network includes a first pair of conductors for performing at least the function of transmitting data from the PD to the PSE and the circuitry for current modulating will remain operable to communicate the message from the PD to the PSE even if both conductors of said first pair of conductors are shorted together.

51. A powered device (PD) having a requirement for a minimum level of inline power supplied over a wired data telecommunications network from power sourcing equipment (PSE) to which the PD is coupled, the minimum level of inline power requirement subject to change from time to time, the PD comprising:

circuitry for determining a minimum level of inline power required by the PD at a particular time;

circuitry for current modulating the inline power supplied over the wired data telecommunications network; and

an encoder for encoding a message from the PD to the PSE on the current modulating circuitry communicating a present need for a minimum level of inline power.

52. The apparatus of claim 51, wherein:

the circuitry for current modulating comprises at least one current source or current sink.

53. A powered device (PD) having a requirement for a minimum level of inline power supplied over a wired data telecommunications network from power sourcing equipment (PSE) to which the PD is coupled, the minimum level of inline power requirement subject to change from time to time, the PD comprising:

means for determining a minimum level of inline power required by the PD at a particular time;

means for current modulating the inline power supplied over the wired data telecommunications network; and

means for encoding a message from the PD to the PSE on the current modulating means communicating a present need for a minimum level of inline power.

54. The apparatus of claim 53, wherein:

the means for current modulating comprises at least one current source or current sink.

79. The PD of claim 53, wherein:

the PD takes a first amount of time to complete a bootstrap operation after first application of power thereto, and

the determining means, modulating means and encoding means are all operable in less than said first amount of time.

55. A method for operating a powered device (PD) having a requirement for a minimum level of inline power supplied over a wired data telecommunications network from power sourcing equipment (PSE) to which the PD is coupled, the minimum level of inline power requirement subject to change from time to time, the method comprising:

determining a minimum level of inline power required by the PD at a particular time; and

encoding a message from the PD to the PSE by current modulating the inline power supplied over the wired data telecommunications network to the PD to communicate a need for a minimum level of inline power.

56. The method of claim 55, wherein:

the current modulating is accomplished using at least one current source or current sink.

80. The method of claim 55, further comprising:

bootstrapping the PD for operation, wherein;

the determining, modulating and encoding are able to take place prior to the completion of the bootstrapping.

57. A powered device (PD) coupled with a wired data telecommunications network to power sourcing equipment (PSE), the PD comprising:

information storage memory for containing a representation of information to communicate from the PD to the PSE;

circuitry for current modulating the inline power supplied over the wired data telecommunications network to the PD; and

an encoder for encoding a message from the PD to the PSE, containing the information, with the current modulating circuitry.

58. The apparatus of claim 57, wherein:

the circuitry for current modulating comprises at least one current source or current sink.

59. A powered device (PD) coupled with a wired data telecommunications network to power sourcing equipment (PSE), the PD comprising:

means for storing a representation of information to communicate from the PD to the PSE;

means for current modulating the inline power supplied over the wired data telecommunications network to the PD; and

means for encoding a message from the PD to the PSE, containing the information, with the means for current modulating.

60. The apparatus of claim 59, wherein:

the means for current modulating comprises at least one current source or current sink.

61. A method for operating a powered device (PD) coupled with a wired data telecommunications network to power sourcing equipment (PSE), the method comprising:

storing a representation of information to communicate from the PD to the PSE; and

encoding a message from the PD to the PSE, containing the information, by current modulating the inline power supplied over the wired data telecommunications network to the PD.

62. The method of claim 61, wherein:

the current modulating is accomplished using at least one current source or current sink.

63. A power sourcing equipment (PSE) device having a capacity to provide up to a first quantity of inline power over a wired data telecommunications network to a powered device (PD) to which the PSE is coupled, the PSE comprising:

circuitry for receiving a request from the PD for a minimum level of inline power required by the PD at a particular time;

circuitry for voltage modulating the inline power supplied over the wired data telecommunications network from the PSE to the PD; and

an encoder for encoding a message from the PSE to the PD on the voltage modulating circuitry communicating a present minimum level of inline power to be supplied from the PSE to the PD.

64. The apparatus of claim 63, wherein:

the circuitry for voltage modulating comprises at least one transistor or diode.

115. The apparatus of claim 63, wherein:

the circuitry for voltage modulating comprises at least a first power supply set to a first voltage level and a second power supply set to a second voltage level.

65. A power sourcing equipment (PSE) device having a capacity to provide up to a first quantity of inline power over a wired data telecommunications network to a powered device (PD) to which the PSE is coupled, the PSE comprising:

means for receiving a request from the PD for a minimum level of inline power required by the PD at a particular time;

means for voltage modulating the inline power supplied over the wired data telecommunications network from the PSE to the PD; and

means for encoding a message from the PSE to the PD on the voltage modulating means communicating a present minimum level of inline power to be supplied from the PSE to the PD.

66. The apparatus of claim 65, wherein:

the means for voltage modulating comprises at least one transistor or diode.

67. A method for operating a power sourcing equipment (PSE) device having a capacity to provide up to a first quantity of inline power over a wired data telecommunications network to a powered device (PD) to which the PSE is coupled, the method comprising:

receiving a request from the PD for a minimum level of inline power required by the PD at a particular time;

voltage modulating the inline power supplied over the wired data telecommunications network from the PSE to the PD; and

encoding a message from the PSE to the PD with said voltage modulating communicating a present minimum level of inline power to be supplied from the PSE to the PD.

68. The method of claim 67, wherein:

the voltage modulating is accomplished using at least one transistor or diode.

81. The method of claim 67, further comprising:

bootstrapping the PSE for operation, wherein;

the receiving, modulating and encoding are able to take place prior to the completion of the bootstrapping.

69. A power sourcing equipment (PSE) device coupled with a wired data telecommunications network to a powered device (PD), the PSE comprising:

information storage memory for containing a representation of information to communicate from the PSE to the PD;

circuitry for voltage modulating the inline power supplied over the wired data telecommunications network from the PSE to the PD; and

an encoder for encoding a message from the PSE to the PD, containing the information, with the voltage modulating circuitry.

70. The apparatus of claim 69, wherein:

the circuitry for voltage modulating comprises at least one transistor or diode.

71. A power sourcing equipment (PSE) device coupled with a wired data telecommunications network to powered equipment (PD), the PSE comprising:

means for storing a representation of information to communicate from the PSE to the PD;

means for voltage modulating the inline power supplied over the wired data telecommunications network from the PSE to the PD; and

means for encoding a message from the PSE to the PD, containing the information, with the means for voltage modulating.

72. The apparatus of claim 71, wherein:

the means for voltage modulating comprises at least one transistor or diode.

82. The PSE of claim 71, wherein:

the PSE takes a first amount of time to complete a bootstrap operation after first application of power thereto, and

the storing means, modulating means and encoding means are all operable in less than said first amount of time.

73. A method for operating a power sourcing equipment (PSE) device coupled with a wired data telecommunications network to a powered device (PD), the method comprising:

storing a representation of information to communicate from the PSE to the PD;

voltage modulating the inline power supplied over the wired data telecommunications network to the PD; and

encoding a message from the PSE to the PD, containing the information, with said voltage modulating.

74. The method of claim 73, wherein:

the voltage modulating is accomplished using at least one transistor or diode.

75. A voice over internet protocol telephone system, comprising:

an internet protocol switch providing inline power as power sourcing equipment (PSE) to attached voice over internet protocol telephones as powered devices (PDs);

means for establishing an initial inline power relationship whereby a PD requests and receives up to a first minimum level of inline electrical power from an attached PSE at a first time;

means for determining a change in the power desired by a PD from an attached PSE;

first communicating means responsive to the determining means for communicating a request for a second minimum level of inline electrical power to be supplied by the PSE to the attached PD; and

means responsive to the first communicating means for receiving the request for a second minimum level of inline electrical power and providing it to the attached PD at a second time.

76. The system of claim 75, further comprising:

second communicating means for communicating a second minimum level of inline electrical power to be supplied by the PSE to the attached PD.

77. The system of claim 76, wherein:

the first communicating means utilizes current modulation to communicate the request.

78. The system of claim 77, wherein:

the second communicating means utilizes voltage modulation to communicate the second minimum level of inline electrical power to be supplied.

83. A telecommunications system, comprising:

a wired data telecommunications network segment;

a power sourcing equipment (PSE) device having a capacity to provide up to a first quantity of inline power over the wired data telecommunications network segment to a powered device (PD) to which the PSE is coupled, the PSE further comprising;

first means for demodulating a first message from the PD received as modulated inline power over the wired data telecommunications network segment;

first means for modulating the inline power supplied over the wired data telecommunications network segment from the PSE to the PD to communicate a second message from the PSE to the PD;

a powered device (PD) coupled to the PSE with the wired data telecommunications network segment, the PD further comprising;

second means for demodulating the second message from the PSE received as modulated inline power over the wired data telecommunications network segment; and

second means for modulating the inline power supplied over the wired data telecommunications network segment from the PD to the PSE to communicate the first message from the PD to the PSE.

84. The system of claim 83, wherein the first and second modulating means and the first and second demodulating means are simultaneously operable to provide full-duplex communications to the PSE and PD.

85. The system of claim 83, wherein the first and second modulating means and the first and second demodulating means are sequentially operable to provide half-duplex communications to the PSE and PD.

86. The system of claim 83, wherein the first modulating means is a voltage modulator.

87. The system of claim 83, wherein the second modulating means is a voltage modulator.

88. The system of claim 83, wherein the second modulating means is a current modulator.

89. The system of claim 86, wherein the first demodulating means is a current demodulator.

90. The system of claim 87, wherein the second demodulating means is a voltage demodulator.

95. A powered device (PD) for communicating a message to power sourcing equipment (PSE) in a wired data telecommunications network, the PD comprising:

a first circuit for participating in a PD detection and classification process to verify that the PD may be supplied with inline power from the PSE;

a second circuit responsive to said first circuit, for establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

a third circuit for current modulating the power at the PD with a predetermined communications protocol to communicate the message from the PD to the PSE.

96. A power sourcing equipment (PSE) device for receiving a message from a powered device (PD) in a wired data telecommunications network, the PSE comprising:

a first circuit for participating in a detection and classification process to verify that the PD may be supplied with inline power from the PSE;

a second circuit responsive to said first circuit, for establishing an initial inline power relationship between the PD and the PSE so that the PD is receiving an initial minimum level of power from the PSE; and

a third circuit for demodulating a modulated current signal at the PSE received from the PD to receive the message from the PD at the PSE.

97. A method for communicating a message from a first station via a second station to a third station in a wired data telecommunications network, the first station comprising a powered device (PD), the second station comprising power sourcing equipment (PSE), and the third station comprising a PD, and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the second station and at least a third pair of conductors and a fourth pair of conductors for coupling the second station to the third station, the method comprising:

biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage levels being a first difference voltage; and

voltage modulating the difference voltage with a predetermined communications protocol to communicate the message from the first station to the second station;

transmitting the message from the first station to the second station.

98. The method of claim 97, further comprising:

biasing the third pair of conductors with the one DC voltage level and the fourth pair of conductors with the second DC voltage level, the difference between the third and fourth voltage levels being a second difference voltage; and

voltage modulating the second difference voltage with a predetermined communications protocol to communicate the message from the second station to the third station;

transmitting the message from the second station to the third station.

99. The method of claim 97, further comprising:

biasing the third pair of conductors with the one DC voltage level and the fourth pair of conductors with the second DC voltage level, the difference between the third and fourth voltage levels being a second difference voltage; and

current modulating the second difference voltage with a predetermined communications protocol to communicate the message from the second station to the third station;

transmitting the message from the second station to the third station.

100. A method for communicating a message from a first station via a second station to a third station in a wired data telecommunications network, the first station comprising a powered device (PD), the second station comprising power sourcing equipment (PSE), and the third station comprising a PD, and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the second station and at least a third pair of conductors and a fourth pair of conductors for coupling the second station to the third station, the method comprising:

biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage levels being a first difference voltage; and

current modulating the difference voltage with a predetermined communications protocol to communicate the message from the first station to the second station;

transmitting the message from the first station to the second station.

101. The method of claim 100, further comprising:

biasing the third pair of conductors with the one DC voltage level and the fourth pair of conductors with the second DC voltage level, the difference between the third and fourth voltage levels being a second difference voltage; and

voltage modulating the second difference voltage with a predetermined communications protocol to communicate the message from the second station to the third station;

transmitting the message from the second station to the third station.

102. The method of claim 100, further comprising:

biasing the third pair of conductors with the one DC voltage level and the fourth pair of conductors with the second DC voltage level, the difference between the third and fourth voltage levels being a second difference voltage; and

current modulating the second difference voltage with a predetermined communications protocol to communicate the message from the second station to the third station;

transmitting the message from the second station to the third station.

103. A method for communicating a message from a first station via a second station to a third station in a wired data telecommunications network, the first station comprising a powered device (PD), the second station comprising power sourcing equipment (PSE), and the third station comprising a PD, and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station, the second station and the third station, the method comprising:

biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage levels being a difference voltage; and

voltage modulating the difference voltage with a predetermined communications protocol to communicate the message from the first station to the second station;

transmitting the message from the first station to the second station.

104. The method of claim 103, further comprising:

current modulating the difference voltage with a predetermined communications protocol to communicate the message from the second station to the third station;

transmitting the message from the second station to the third station.

106. The method of claim 103, further comprising:

current modulating the difference voltage with a predetermined communications protocol to communicate the second message from the second station to the first station;

transmitting the second message from the second station to the first station.

105. A method for communicating a first message from a first station to a third station and a second message from the second station to the first station in a wired data telecommunications network, a second station providing inline power to the first station and the second station, the first station comprising a powered device (PD), the second station comprising power sourcing equipment (PSE), and the third station comprising a PD, and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station, the second station and the third station, the method comprising:

biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage levels being a difference voltage; and

voltage modulating the difference voltage with a predetermined communications protocol to communicate the first message from the first station to the second station;

transmitting the first message from the first station to the second station.

122. A method for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station and the second station comprising power sourcing equipment (PSE), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the method comprising:

periodically conducting at the first station a first discovery process to determine if a powered device (PD) is present on the wired data telecommunications network, followed by a back off period;

listening during the back off period for a special signature indicating the presence of a PSE at the second station;

detecting the presence of a PSE at the second station; and

communicating, responsive to said detecting, with the PSE at the second station.

123. The method of claim 122, wherein said special signature comprises a unique identity network associated with PSEs.

124. The method of claim 122, wherein said special signature comprises a unique modulated signal associated with PSEs.

125. The method of claim 122, wherein said communicating takes place by modulating an inline power signal between the first station and the second station.

126. The method of claim 125, wherein said modulating includes current modulating.

127. The method of claim 125, wherein said modulating includes voltage modulating.

128. The method of claim 122, further comprising:

biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

current modulating a current flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

129. The method of claim 128, wherein said modulating takes place while at least one of the first station and the second station is powered by the difference voltage.

130. An apparatus for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station and the second station comprising power sourcing equipment (PSE), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the apparatus comprising:

means for periodically conducting at the first station a first discovery process to determine if a powered device (PD) is present on the wired data telecommunications network, followed by a back off period;

means for listening during the back off period for a special signature indicating the presence of a PSE at the second station;

means for detecting the presence of a PSE at the second station; and

means for communicating, responsive to said detecting, with the PSE at the second station.

131. The apparatus of claim 130, wherein said special signature comprises a unique identity network associated with PSEs.

132. The apparatus of claim 130, wherein said special signature comprises a unique modulated signal associated with PSEs.

133. The apparatus of claim 130, wherein said means for communicating modulates an inline power signal between the first station and the second station.

134. The apparatus of claim 133, wherein said means for modulating current modulates.

135. The apparatus of claim 133, wherein said means for modulating voltage modulates.

136. The apparatus of claim 130, further comprising:

means for biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

means for current modulating a current flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

137. The apparatus of claim 136, wherein at least one of the first station and the second station is powered by the difference voltage.

138. A system for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station and the second station comprising power sourcing equipment (PSE), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the system comprising:

circuitry for periodically conducting at the first station a first discovery process to determine if a powered device (PD) is present on the wired data telecommunications network, followed by a back off period;

circuitry for listening during the back off period for a special signature indicating the presence of a PSE at the second station;

circuitry for detecting the presence of a PSE at the second station; and

circuitry for communicating, responsive to said detecting, with the PSE at the second station.

139. The system of claim 138, wherein said special signature comprises a unique identity network associated with PSEs.

140. The system of claim 138, wherein said special signature comprises a unique modulated signal associated with PSEs.

141. The system of claim 138, wherein said circuitry for communicating modulates an inline power signal between the first station and the second station.

142. The system of claim 141, wherein said circuitry for modulating current modulates.

143. The system of claim 141, wherein said circuitry for modulating voltage modulates.

144. The system of claim 138, further comprising:

circuitry for biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

circuitry for current modulating a current flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

145. The system of claim 144, wherein at least one of the first station and the second station is powered by the difference voltage.

146. An apparatus for communicating a message from a first station to at least one second station in a wired data telecommunications network, the first station and the second station comprising power sourcing equipment (PSE), and the wired data telecommunications network having at least a first pair of conductors and a second pair of conductors for coupling the first station to the at least one second station, the apparatus comprising:

a discoverer for periodically conducting at the first station a first discovery process to determine if a powered device (PD) is present on the wired data telecommunications network, followed by a back off period;

a receiver for listening during the back off period for a special signature indicating the presence of a PSE at the second station;

a detector for detecting the presence of a PSE at the second station; and

a communicator for communicating, responsive to said detecting, with the PSE at the second station.

147. The apparatus of claim 146, wherein said special signature comprises a unique identity network associated with PSEs.

148. The apparatus of claim 146, wherein said special signature comprises a unique modulated signal associated with PSEs.

149. The apparatus of claim 146, wherein said communicator modulates an inline power signal between the first station and the second station.

150. The apparatus of claim 149, wherein said communicator utilizes current modulation.

151. The apparatus of claim 149, wherein said communicator utilizes voltage modulation.

152. The apparatus of claim 146, further comprising:

a biaser for biasing the first pair of conductors with one direct current (DC) voltage level and the second pair of conductors with a second DC voltage level, the difference between the first and second voltage level being a difference voltage; and

a modulator for modulating a signal flowing from the first pair of conductors to the second pair of conductors with a predetermined communications protocol to communicate the message from the first station to the at least one second station.

153. The apparatus of claim 152, wherein at least one of the first station and the second station is powered by the difference voltage.