Powered device classification in a wired data telecommunications network

• US 8,972,757 B2
• Filed: 12/18/2013
• Issued: 03/03/2015
• 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:
  US14/133,468
• Publication Number:
  US 20140108847A1
• Time in Patent Office: 440 Days
• 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 system, comprising:

a computing device processor; and

a memory device including instructions that, when executed by the computing device processor, cause the system to;

initiate an inline power discovery cycle in response to an interrupted flow of inline power between power source equipment (PSE) and a powered device (PD) responding to a security alert input, wherein the inline power is received at the PD from and coupled to the PSE in a wired data communications network having conductors coupling the PD and the PSE;

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

conduct 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 to yield measured current, and

determining a class corresponding to the measured current to yield a plurality of classes over the plurality of inline power classification cycles;

combine the plurality of classes into a classification code for the PD; and

determine that the classification code corresponds to a predetermined security message.

2. The system of claim 1, wherein the instructions when executed further cause the system to:

sound an alarm responsive to receipt of the predetermined security message.

3. The system of claim 1, wherein the instructions when executed further cause the system to:

forward an alarm message in response to receipt of the predetermined security message.

4. The system of claim 1, wherein the instructions when executed further cause the system to:

during the plurality of inline power classification cycles, concurrently drop a voltage signal applied to the conductors below a reset logic level between classification cycles.

5. The system of claim 1, wherein the instructions when executed further cause the system to:

during the plurality of inline power classification cycles, concurrently ramp a voltage signal applied to the conductors to a marker level voltage between classification cycles, the marker level voltage being outside a range of the classification voltage and above a reset logic level for the PD.

6. A method, comprising:

in response to an interrupted flow of inline power between power sourcing equipment (PSE) and a powered device (PD), discovering that the PD is adapted to receive inline power from the PSE, wherein the PD is coupled to the PSE in a wired data communications network having conductors coupling the PD and the PSE;

applying a classification voltage to the conductors;

measuring current in the conductors to yield measured current; and

determining that the measured current corresponds to a security message.

7. The method of claim 6, further comprising:

in response to determining that the measured current corresponds to the security message, sounding an alarm.

8. The method of claim 6, further comprising:

in response to determining that the measured current corresponds to the security message, forwarding an alarm message.

9. The method of claim 6, wherein the security message is manually initiated.

10. The method of claim 6, wherein the security message is initiated in response to a sensor output.

11. The method of claim 6, wherein the classification voltage is a voltage in a range of about 15 volts DC (direct current) to about 20 volts DC.

12. The method of claim 6, wherein determining that the measured current corresponds to the security message comprises using a lookup table indexed by current value to identify the security message associated with the measure current.

13. The method of claim 6, wherein the conductors comprise two pairs of conductors.

14. The method of claim 6, wherein the conductors comprise four pairs of conductors.

15. The method of claim 6, wherein the current is measured while the classification voltage is applied to the conductors.

16. The method of claim 6, further comprising:

measuring a series of current levels in the conductors;

determining a plurality of classes based on the series of current levels; and

combining the plurality of classes into a classification code, wherein determining that the measured current corresponds to the security message is based on the classification code.

17. A non-transitory computer-readable storage medium storing instructions which, when executed by a processor, cause the processor to perform operations comprising:

in response to an interrupted flow of inline power between power sourcing equipment (PSE) and a powered device (PD), discovering that the PD is adapted to receive inline power from the PSE, wherein the PD is coupled to the PSE in a wired data communications network having conductors coupling the PD and the PSE;

applying a classification voltage to the conductors;

measuring current in the conductors to yield measured current; and

determining that the measured current corresponds to a security message.

18. The non-transitory computer-readable storage medium of claim 17, storing additional instructions which, when executed by the processor, cause the processor to perform the operations further comprising:

in response to determining that the measured current corresponds to the security message, sounding an alarm.

19. The non-transitory computer-readable storage medium of claim 17, storing additional instructions which, when executed by the processor, cause the processor to perform the operations further comprising:

in response to determining that the measured current corresponds to the security message, forwarding an alarm message.

20. The non-transitory computer-readable storage medium of claim 17, wherein the security message is initiated at the PD in response to a sensor output.