Response mechanisms for power-interruption events in PoE systems

1. A method comprising:

receiving, at a Power Sourcing Equipment (PSE), power from at least a first Power Supply Unit (PSU) and a second PSU;

providing power to at least a first Powered Device (PD) via a first Ethernet cable and a second PD via a second Ethernet cable;

detecting, by processing circuitry in the PSE, while providing power to the first PD and the second PD, an interruption to a flow of power from the first PSU to the PSE; and

in response to detecting the interruption:

ceasing to provide power to the first PD via the first Ethernet cable while continuing to provide power to the second PD via the second Ethernet cable;

sending a first network communication from the PSE to the second PD indicating that the interruption has occurred and requesting that the second PD enter a power-saving mode of the second PD;

receiving a second network communication sent from the second PD to the PSE in response to the first network communication, the second network communication indicating whether the second PD is willing to enter the power-saving mode of the second PD;

based on the second network communication, reducing an amount of power allocated to the second PD from an initial value to a reduced value;

allocating an amount of power to the first PD that is based on a difference between the initial value and the reduced value; and

instructing the first PD to power on in a power-saving mode of the first PD.

2. The method of claim 1 , wherein the first network communication comprises a link-layer discovery protocol communication comprising a PSE power status field and a bit in the PSE power status field that indicates the interruption by specifying a fault status of the first PSU.

3. The method of claim 1 , wherein the second network communication comprises a link-layer discovery protocol communication comprising a PD power status field and one or more bits in the PD power status field that indicate whether the second PD is willing to switch to the power-saving mode of the second PD.

4. The method of claim 3 , wherein the PD power status field further comprises a plurality of bits that indicate how much power the second PD has to receive in order to operate in the power-saving mode of the second PD.

5. The method of claim 3 , wherein the PD power status field further comprises a plurality of bits that indicate an expected amount of power that the second PD is expected to consume while operating in a normal mode.

6. The method of claim 1 , further comprising:

determining the amount of power allocated to the first PD is insufficient to power the first PD in the power-saving mode of the first PD;

sending a third network communication from the PSE to a third PD that continues to receive power from the PSE via a third Ethernet cable after the interruption, the third network communication indicating that the interruption has occurred and requesting that the third PD enter a power-saving mode of the third PD;

receiving a fourth network communication sent from the third PD to the PSE in response to the third network communication, the fourth network communication indicating whether the third PD is willing to enter the power-saving mode of the third PD;

based on the fourth network communication, reducing an amount of power allocated to the third PD from an additional initial value to an additional reduced value; and

allocating an additional amount of power to the first PD that is based on a difference between the additional initial value and the additional reduced value.

7. The method of claim 1 , further comprising:

detecting that the interruption has been resolved such that the flow of power from the first PSU to the PSE has resumed;

increasing the amount of power allocated to the second PD from the reduced value back to the initial value; and

increasing the amount of power allocated to the first PD to a value that is sufficient to power the first PD in a normal operating mode of the first PD.

8. The method of claim 1 , further comprising, in response to the second communication indicating that the second PD is willing to enter the power-saving mode of the second PD, setting the reduced value based on a power-saving mode consumption amount corresponding to an amount of power the second PD is expected to consume in the power-saving mode of the second PD.

9. The method of claim 1 , wherein the second communication further indicates a normal mode consumption amount corresponding to an amount of power the second PD is expected to consume while operating in a normal mode of the second PD and the method further comprises, in response to the second communication indicating that the second PD is not willing to enter the power-saving mode of the second PD, setting the reduced value to equal the normal mode consumption amount plus a defined offset.

10. A Power Sourcing Equipment (PSE) comprising:

one or more processors;

a first Ethernet port;

a second Ethernet port; and

a memory storing instructions that, when executed on the one or more processors, cause the PSE to:

receive, at the PSE, power from at least a first Power Supply Unit (PSU) and a second PSU;

provide power to at least a first Powered Device (PD) via a first Ethernet cable plugged into the first Ethernet port and a second PD via a second Ethernet cable plugged into the second Ethernet port;

detect, by the one or more processors in the PSE while providing power to the first PD and the second PD, an interruption in a flow of power from the first PSU to the PSE; and

in response to detecting the interruption:

cease to provide power to the first PD via the first Ethernet cable while continuing to provide power to the second PD via the second Ethernet cable;

send a first network communication from the PSE to the second PD indicating that the interruption has occurred and requesting that the second PD enter a power-saving mode of the second PD;

receive a second network communication sent from the second PD to the PSE in response to the first network communication, the second network communication indicating whether the second PD is willing to enter the power-saving mode of the second PD;

based on the second network communication, reduce an amount of power allocated to the second PD from an initial value to a reduced value;

allocate an amount of power to the first PD that is based on a difference between the initial value and the reduced value; and

instruct the first PD to power on in a power-saving mode of the first PD.

11. The PSE of claim 10 , wherein the first network communication a link-layer discovery protocol communication comprising a PSE power status field and a bit in the PSE power status field that indicates the interruption by specifying a fault status of the first PSU.

12. The PSE of claim 10 , wherein the second network communication comprises a link-layer discovery protocol communication comprising a PD power status field and one or more bits in the PD power status field that indicate whether the second PD is willing to switch to the power-saving mode of the second PD.

13. The PSE of claim 12 , wherein the PD power status field further comprises a plurality of bits that indicate how much power the second PD has to receive in order to operate in the power-saving mode of the second PD.

14. The PSE of claim 12 , wherein the PD power status field further comprises a plurality of bits that indicate an expected amount of power that the second PD is expected to consume while operating in a normal mode of the second PD.

15. The PSE of claim 10 , wherein the instructions cause the PSE to:

in response to the second communication indicating that the second PD is willing to enter the power-saving mode of the second PD, set the reduced value based on a power-saving mode consumption associated with the power-saving mode of the second PD; and

in response to the second communication indicating that the second PD is not willing to enter the power-saving mode of the second PD, set the reduced value based on a normal mode consumption amount associated with a normal mode of the second PD.

16. The PSE of claim 15 , wherein the second communication indicates the normal mode consumption amount which corresponds to an amount of power the second PD is expected to consume in the normal mode of the second PD and setting the reduced value based on the normal mode consumption amount comprises setting the reduced value to equal the normal mode consumption amount plus a defined offset.

17. A powered device (PD) comprising:

one or more processors;

an Ethernet port; and

a memory storing instructions that, when executed on the one or more processors, cause the PD to:

receive, at the PD, power from a Power Sourcing Equipment (PSE) via an Ethernet cable that is plugged into the Ethernet port;

receive a first network communication from the PSE indicating an interruption in a flow of power from a PSU to the PSE and requesting that the PD enter a power-saving mode;

in response to the first network communication, determine by the one or more processors whether to switch into the power-saving mode and send a second network communication to the PSE;

in response to determining to enter the power-saving mode, cause the second network communication to indicate that the PD is willing to switch to the power-saving mode, and enter the power-saving mode; and

in response to determining not to enter the power-saving mode, cause the second network communication to indicate that the PD is not willing to switch to the power-saving mode, and remain in a normal mode.

18. The PD of claim 17 , wherein the second network communication comprises a link-layer discovery protocol communication comprising a PD power status field and one or more bits indicating whether the PD is willing to switch to the power-saving mode.

19. The PD of claim 18 , wherein the PD power status field further comprises a plurality of bits that indicate how much power the PD has to receive in order to operate in the power-saving mode.

20. The PD of claim 18 , wherein the PD power status field further comprises a plurality of bits that indicate an expected amount of power that the PD is expected to consume while operating in a normal mode.