Powered device classification in a wired data telecommunications network

• US 8,635,473 B2
• Filed: 10/03/2012
• Issued: 01/21/2014
• Est. Priority Date: 11/03/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Karam, Roger A., Wakerly, John F.
• Primary Examiner(s): BUTLER, DENNIS
• Application Number:
  US13/644,221
• Publication Number:
  US 20130057056A1
• Time in Patent Office: 475 Days
• Field of Search: None
• US Class Current: 713/310
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 12/44 Star or tree networks

Abstract

In a wired data telecommunication network power sourcing equipment (PSE) coupled to a powered device (PD) carries out an inline power discovery process to verify that the PD is adapted to receive inline power, then a plurality of classification cycles are carried out to convey a series of inline power classes back to the PSE. The series of inline power classes may all be the same, in which case the PD is legacy equipment and is adapted to receive the power level corresponding to that class. If they are not all the same, information is thus conveyed to the PSE which may, for example, correspond to a specific power level to be applied or to other information.

Claims

1. A method of operating a power sourcing equipment (PSE) to implement 4-conductor pair power for a powered device (PD) receiving inline power from and coupled to the PSE in a wired data telecommunications network having at least four pairs of conductors coupling the PD and the PSE, comprising:

initiating an inline power discovery cycle;

discovering that the PD is adapted to receive inline power from the PSE;

conducting a plurality of inline power classification cycles, each comprising;

applying a classification voltage to the conductors;

measuring current in the conductors while the classification voltage is applied; and

determining a class corresponding to the measured current;

combining the plurality of classes determined into a classification code for the PD;

determining that the classification code corresponds to a request for 4-conductor power; and

configuring the PSE in response to said determining to provide 4-conductor inline power to the PD,

wherein a voltage applied to the PD by the PSE ramps to a marker level voltage between successive ones of the inline power classification cycles, the marker level voltage being outside the classification voltage range and above a reset logic level for the PD.

2. The method of claim 1, wherein the classification voltage is a voltage in a range of about 15 volts DC (direct current) to about 20 volts DC.

3. The method of claim 1, wherein said determining a class includes:

using a look up table indexed by measured current value to determine a class responsive to the measured current value.

4. The method of claim 1, further comprising:

initiating said conducting in response to a command.

5. The method of claim 1, further comprising:

initiating said conducting in response to interruption of inline power delivery from the PSE to the PD.

6. The method of claim 1, further comprising:

monitoring the current drawn by the PD over the conductors and, if it exceeds a predetermined level during said conducting, terminating said conducting.

7. The method of claim 1, wherein said conducting is carried out over two pairs of the four pairs of conductors.

8. The method of claim 1, wherein said conducting is carried out over all pairs of the four pairs of conductors.

9. A method of operating a powered device (PD) to implement 4-conductor pair power for the PD receiving inline power from and coupled to a power sourcing equipment (PSE) in a wired data telecommunications network having at least four pairs of conductors coupling the PD and the PSE, the method comprising:

during an inline power discovery cycle, presenting a predetermined identity network to the conductors to indicate to the PSE that the PD is adapted to receive inline power from the PSE;

for each of a subsequent plurality of inline power classification cycles;

receiving a classification voltage on the conductors; and

applying a classification current to the conductors while the classification voltage is applied to indicate to the PSE a class corresponding to the applied classification current, wherein a sequence of classes indicated to the PSE over the plurality of inline power classification cycles forms a classification code determinable by the PSE to be a request for 4-conductor power;

subsequently receiving 4-conductor inline power from the PSE based on a determination by the PSE that the sequence of classes indicated by the PD form the request for 4-conductor power; and

storing in nonvolatile memory at the PD a representation that a classification procedure is underway, the nonvolatile memory adapted to store information for a period of time in the absence of inline power voltage exceeding a reset logic level.

10. The method of claim 9, wherein the classification voltage is a voltage in a range of about 15 volts DC (direct current) to about 20 volts DC.

11. The method of claim 9, further comprising:

interrupting delivery of inline power delivery from the PSE to the PD to initiate the inline power discovery cycle and subsequent plurality of classification cycles.

12. The method of claim 9, wherein a voltage signal applied to the conductors during the plurality of classification cycles is dropped below a reset logic level between classification cycles.

13. The method of claim 9, wherein a voltage applied to the PD by the PSE ramps to a marker level voltage between successive ones of the inline power classification cycles, the marker level voltage being outside the classification voltage range and above a reset logic level for the PD.

14. The method of claim 9, further comprising:

the classification currents applied by the PD to the conductors are maintained less than a predetermined level indicative of an overcurrent condition.

15. The method of claim 9, wherein said plurality of classification cycles is carried out over two pairs of the four pairs of conductors.

16. The method of claim 9, wherein said plurality of classification cycles is carried out over all pairs of the four pairs of conductors.

17. The method of claim 9, wherein the nonvolatile memory is powered by a capacitor disposed at the PD, the capacitor drawing charge from voltage applied to the conductors.