Power priority adjustment for Power over Ethernet systems based on alternative power availability

Abstract

This disclosure relates to power priority adjustment in a Power over Ethernet (PoE) system based on the availability of alternative power sources. A PoE powered device (PD) can be coupled to a PoE power supply device (PSE). The PD can send link-layer protocol communications to the PSE, including an alternative power field indicating whether the sending PD has an alternative power source (e.g., battery, local power). The PSE can listen to and receive the communications and read the alternative power field therein. The PSE can set an appropriate power priority for the PD based at least in part on whether the PD has the corresponding alternative power source, as indicated by the corresponding alternative power field in its communications. The PSE can lower the power priority of those PDs that have an alternative power source relative to the priority otherwise assigned to the PD.

Description

Background Technology

[0001] Power over Ethernet (PoE) allows data signals and power signals to be transmitted over the same Ethernet cable. This allows PoE-enabled electronic devices to be communicatively coupled to the network and receive power via the same cable, providing greater flexibility in device deployment (e.g., devices no longer need to be placed near power outlets or have long power cords to reach them). In a PoE system, devices that provide power to other devices via PoE are called power sourcing equipment (PSEs), and devices that receive power from PSEs are called powered devices (PDs). PSEs are also commonly used as networking elements, such as switches or routers. PDs can also be networking elements (e.g., wireless access points, PoE repeaters / hubs, etc.), network endpoints (e.g., security cameras, Internet of Things (IoT) devices, etc.), or any other electronic device with a PoE port.

[0002] In PoE systems, under certain circumstances, the total power that a Power Provider (PSE) can provide at a given time (“available power”) may be less than the total power that all connected Devices (PDs) are consuming or expect to consume at the same time (“power demand”). A power demand exceeding the PSE’s available power is referred to herein as a “PSE power failure”. A PSE power failure can occur for a variety of reasons. For example, a PSE may be designed so that the maximum total power it can provide is less than the sum of the maximum output power per port. For instance, if a hypothetical PSE has a maximum total output power of 80W and six ports, each of which can individually provide a maximum of 20W per port, then the sum of the maximum output power per port (6 × 20W = 120W) exceeds the available power (80W). In such an example, if all ports of the PSE are coupled to PDs consuming the full maximum power per port, then the power demand at that time will exceed the available power. As another example, even if a PSE is designed to have a maximum total power output equal to or greater than the sum of the maximum output power per port, the actual available power at a given time may drop below the maximum available power under certain circumstances, such as due to a PSE power failure or other failure events. Attached Figure Description

[0003] This disclosure can be understood from the following detailed description, whether alone or in conjunction with the appendix. Figure 1 The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and form a part of this specification. The drawings illustrate one or more examples of the teachings of this disclosure and, together with the specification, explain certain principles and operations.

[0004] In the attached diagram:

[0005] Figure 1 This is a block diagram illustrating an example PoE PSE.

[0006] Figure 2 This is a block diagram illustrating an example PoE PD.

[0007] Figure 3 This is a block diagram illustrating an example PoE system including a PSE and a PD coupled thereto.

[0008] Figure 4 This is a flowchart illustrating the first example method that can be executed by PoE PSE.

[0009] Figure 5 This is a flowchart illustrating a second example method that can be executed by PoE PSE.

[0010] Figure 6 This is a flowchart illustrating a third example method that can be executed by PoE PSE.

[0011] Figure 7 This is a block diagram illustrating an example storage medium that stores instructions executable by a PoE PSE processor.

[0012] Figure 8 This is a block diagram illustrating an example storage medium that stores instructions executable by a processor of a PoE PD.

[0013] Figure 9 This is a flowchart illustrating the fourth example method that can be executed by PoE PSE. Detailed Implementation

[0014] In some PoE systems, the Power Provider Interface (PSE) assigns power priorities to the Devices Activated (PDs) connected to it. In the event of a PSE power failure, power priorities indicate which PDs will receive power preferentially. That is, when a PSE power failure occurs, the PSE will select a first group of PDs to which it will continue to receive PoE power and a second group of PDs to which it will stop receiving PoE power. The first group includes PDs with higher power priorities, and the second group includes PDs with lower power priorities relative to the other PDs. The PSE can seek to maximize the number of PDs in the first group that will continue to receive PoE power while keeping power demand at or below available power. For example, the PSE can select n highest priority PDs to continue receiving PoE power, where n is the maximum number that will result in power demand equal to or below available power. Alternatively, equivalently, the PSE can identify p lowest priority PDs to stop receiving PoE power, where p is the minimum number that will result in power demand equal to or below available power. Note that "highest" and "lowest" here are relative to other PDs coupled to the PSE, not absolute highest and lowest priorities. If there are more highest-priority power selectors (PDs) than can be included in the first group (e.g., including all highest-priority PDs would exceed available power), then one or more of the highest-priority PDs will be excluded from the first group. Conversely, if there is additional power margin after adding all the highest-priority PDs in the first group, the PSE can consider the next highest priority level and continue selecting PDs with that priority, and so on, down each power priority level, until the number of PDs selected for the first group is maximized while remaining at or below available power. When the PSE needs to choose between two PDs with the same power priority, the PSE can select either PD using any desired selection method, such as random selection or selection based on any other criterion. Therefore, the power priority of a particular PD does not guarantee that the PD will be included or excluded from the first group to continue receiving PoE power, but a higher power priority makes it more likely that the PD will be included in the first group to continue receiving PoE power and also ensures that no lower-priority PD will be selected before a higher-priority PD.

[0015] In many PoE systems, PD power priorities are already set based on PD self-reporting. This means PDs communicate their required priorities to the PSE, and the PSE will set the power priority to whatever the PD indicates. PDs can be configured to request specific power priorities from the PSE, such as during manufacturing and / or later through the user. PDs deemed important or mission-critical can be programmed to request high power priorities (to make them more likely to remain powered in the event of a PSE power failure), while PDs more tolerant of downtime can be programmed to request lower power priorities.

[0016] However, in some cases, when power prioritization is assigned using the methods described above, the prioritization may not result in optimal power distribution within the PD. Specifically, some PDs may access alternative power sources in addition to the power supplied via PoE from the PSE. Such alternative power sources could include backup batteries, local power supplies (e.g., plugs or adapters coupled to the mains power supply), secondary connections to another PSE, or other power sources. If a PD has access to such an alternative power source, the removal of the PoE power supply from the PSE to the PD will not necessarily cause a power outage for the PD, as the PD will be able to rely on its alternative power source (at least for a period of time). Therefore, such a PD does not necessarily need high power priority to ensure it remains powered during a PSE power failure. Assigning high power priority to such a PD can therefore be inefficient, as it may result in other PDs that do require PoE power to remain powered being unable to receive power during a PSE power failure.

[0017] The examples disclosed in this document address the issues noted above, particularly by configuring the PSE to adjust the power priority of PDs if they have access to an alternative power source. More specifically, this involves lowering the power priority of a PD to a level below what it would normally be assigned under the default power priority allocation scheme (which, by default, refers to a power priority allocation scheme used by the PSE that does not consider alternative power sources, such as the power priority assigned to a PD as described above). Therefore, for example, if a PD has an available alternative power source, a PD that would be assigned a (HIGH) power priority under the default power priority allocation scheme might instead be assigned an adjusted MEDIUM or LOW power priority. This reduction in the power priority of PDs with alternative power sources allows more PDs to remain powered during a PSE power failure than might otherwise be possible. Since PDs with alternative power sources can be removed from the set of PDs continuing to receive PoE power (due to their reduced priority), this frees up space for additional sets of PDs that would otherwise lose PoE power, thus enabling an increase in the number of PDs that can remain powered during a PSE failure. Even if a PD with a backup power source is excluded from the set receiving PoE power, it is not powered down because it has a backup power source. Therefore, although the number of PDs receiving PoE power remains unchanged, the total number of PDs that can remain powered up increases.

[0018] For example, consider a hypothetical scenario where the PSE has 60W of available power and four PDs, each consuming 20W, are coupled to the PSE. The first three PDs (PD1, PD2, and PD3) have high power priority, while the fourth PD (PD4) has medium power priority. Since the available power (60W) exceeds the power demand (4 x 20W = 80W), this constitutes a PSE power failure. Therefore, the PSE may need to stop supplying PoE power to one of the PDs to reduce the power demand to the available power level. Under existing methods, the PSE would select the three PDs with the highest priority (PD1, PD2, and PD3) to continue receiving PoE power and would therefore stop supplying PoE power to PD4. Thus, under existing methods, a total of three PDs would remain powered while one PD (PD4) would have to be de-energized. However, if we assume that PD1 has an alternative power source, then in the example described herein, the power priority of PD1 can be reduced to medium. Due to this priority change, the PSE can now select PD2, PD3, and PD4 to continue receiving PoE power, while PD1 stops receiving PoE power (note that in this example, PD1 and PD4 have the same priority, so the PSE can choose either one). Therefore, in this example, all four PDs can remain powered, with PD2, PD3, and PD4 receiving PoE power and PD1 receiving power via its alternative power source. Thus, even though the total available power at the PSE is the same in both scenarios and the number of PDs selected to continue receiving PoE power is the same, the total number of PDs that can remain powered is greater in the latter case due to the adjusted power priority of the PDs with alternative power sources.

[0019] Previously, the PSE typically did not know whether the PD had an alternative power source. Therefore, in the examples disclosed herein, the PD can be configured to transmit this information to the PSE, and the PSE can be configured to listen for this information and then adjust power priorities accordingly as described above. In some examples, link-level discovery protocol communication is used to communicate whether the PD has an alternative power source. Examples of link-layer protocols include the Link Layer Discovery Protocol (LLDP) and other similar protocols. In particular, in some examples, new data fields are defined in the standard communication structure of link-layer discovery protocol communication to indicate whether the PD has an alternative power source, such as the new Type-Length-Value (TLV) field in the Ethernet framework of LLDP communication. This new data field may be referred to herein as the Alt_Pwr field. In the examples disclosed herein, the PD can be configured to include the Alt_Pwr field in its link-layer protocol communication, and the PSE can be configured to monitor this Alt_Pwr field in received link-layer protocol communication.

[0020] In some examples, in addition to indicating in the Alt_Pwr field whether the PD has an alternative power source, the PD may also include information about the alternative power source (if one exists), such as identifying the power source type (e.g., battery, local power supply, etc.) and / or the amount of available power or state of charge. In some examples, the PSE can be configured to consider this additional information when determining the power priority of the PD. For example, the PSE can determine whether the alternative power source is sufficient, and if the alternative power source is insufficient, the PSE can avoid lowering the power priority of the PD. In some examples, if the type of alternative power source is one of a predetermined list of power sources, such as a local power supply coupled to the main power source (e.g., a power adapter), it can be determined that the alternative power source is sufficient. As another example, if the state of charge of a battery-type power supply is above a predetermined threshold, it can be determined that the battery-type power supply is sufficient, and if its state of charge is below that threshold, it can be determined that the battery-type power supply is insufficient.

[0021] In some examples, the PSE can not only adjust the power priority of some PDs based on whether they have a backup power source (as indicated by the Alt_Pwr field in the communication information received from the PD), but the PSE can also consider the existence of a backup power source when selecting a PD to continue receiving PoE power during a PSE power failure. For example, the PSE can select a PD based on its power priority in the manner described above, but when two or more PDs have the same priority and the PSE needs to choose among them, the PSE can be configured to prioritize the PD that does not have a backup power source. Furthermore, in some examples, in response to receiving communication from a PD indicating that the PD has a backup power source, the PSE can proactively initiate negotiation with the PD to stop supplying PoE power to the PD without waiting for a power failure event to occur.

[0022] Furthermore, in some examples, the PSE can sometimes revisit and change the assigned power priority, for example, reverting a PD with an adjusted power priority to the default power priority. For instance, a PD may periodically send updates about its alternative power source via additional link layer discovery protocol communication (via the Alt-Pwr field), and the PSE can change the PD's power priority in response to a change in the state of the PD's alternative power source. For example, if the battery's state of charge drops below a threshold, the PSE can revert the PD's power priority to the default value. Other events detected in other ways can also be used as triggers to revisit the power priority and reset it to the default value.

[0023] Turning now to the accompanying drawings, various devices, systems, and methods according to aspects of this disclosure will be described.

[0024] Figure 1 This is a conceptual block diagram illustrating a PSE for a PoE system, in the form of PSE 110. It should be understood that... Figure 1 It is not intended to show a specific shape, size or other structural details accurately or to scale, and embodiments of PSE 110 may have different numbers and arrangements of the components shown and may also include other parts not shown.

[0025] like Figure 1 As shown, the PSE 110 includes switching hardware 120, power supply 130, multiple PoE ports 140 (“ports 140”), and control circuitry 150.

[0026] Switching hardware 120 includes switching circuitry that can selectively connect port 140 to one other port and one or more other ports (not shown), such as an uplink port, to allow routing of data packets between various devices connected to PSE 110 and other relevant components that participate in, control, or otherwise facilitate the communication of data packets. The switching hardware of the PSE is familiar to those skilled in the art, and therefore switching hardware 120 will not be described in more detail herein.

[0027] Power supply 130 provides power to PSE 110, including power to operate PSE 110 itself and PoE power supplied by PSE 110 to connected PDs via port 140. Power supply 130 can be controlled by control circuitry 150 to selectively supply PoE power to port 140, or in other words, power supply 130 can stop supplying PoE power to certain ports 140 if needed (e.g., during a PSE power failure). Power supply 130 includes one or more power supply devices configured to receive input power from a source such as a mains power supply or power distribution unit and convert that power into a form suitable for use by PSE 110. The power supply devices of power supply 130 may include AC-to-DC converters, DC-to-DC converters, protection devices (e.g., overcurrent protection, overvoltage protection, etc.) and / or other power supply components that participate in, control, or otherwise facilitate the supply of power to PSE 110. The power supply for the PSE is familiar to those skilled in the art, and therefore the power supply 130 will not be described in more detail herein.

[0028] Port 140 includes PoE-capable ports, which may include, for example, RJ45 jacks. Each port 140 is configured to receive a connector for an Ethernet cable, which may include an RJ45 connector. Each port 140 is coupled to control circuitry 150 (e.g., via switching hardware 120) and configured to communicate data between control circuitry 150 and a PD connected to port 140. Each port 140 is also coupled to power supply 130 and configured to supply PoE power from power supply 130 to the PD coupled to port 140 (unless control circuitry 150 has disabled PoE power for port 140). Figure 1 The diagram shows three ports (i.e., ports 140_1, 140_2, and 140_N), but a PSE 110 may include any number of ports 140, equal to or greater than two. Those skilled in the art are familiar with PoE ports, therefore, ports 140 will not be described in more detail herein.

[0029] Control circuitry 150 includes circuitry configured (e.g., programmed) to perform operations 156 and 158. Control circuitry 150 includes a processor and a storage medium storing instructions executable by the processor to cause operations 156 and 158 to be performed, dedicated hardware configured to perform operations 156 and 158, or some combination of these components. In an example where control circuitry 150 includes a processor, the processor may include one or more processing devices capable of executing machine-readable instructions, such as, for example, a processor, central processing unit (CPU), controller, microcontroller, system-on-a-chip (SoC), digital signal processor (DSP), graphics processing unit (GPU), or other processing resources. In an example where control circuitry 150 includes dedicated hardware, as a complement or alternative to the processor, the dedicated hardware may include any electronic device configured to perform specific operations, such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), discrete logic circuitry, hardware accelerators, hardware encoders, etc. In some examples, control circuitry 150 may be configured to control operations other than operations 156 and 158 of PSE 110, such as controlling the operation of switching hardware 120, power supply 130, security / authentication operations, and / or other operations of PSE 110. These other operations of the control circuitry are familiar to those skilled in the art and therefore will not be described in detail herein.

[0030] The control circuitry 150 is configured to perform operation 156, which includes receiving link-layer protocol communication from a PD connected to the PSE 110 (via port 140), wherein the communication includes an Alt_Pwr field indicating whether the PD sending the communication has an alternative power supply. Specifically, the PSE 110 can be configured to monitor link-layer protocol communication, and upon receiving communication, the PSE 110 can check the Alt_Pwr field to determine whether the PD sending the communication has an alternative power supply (in some examples, and to determine other information about the alternative power supply). In some examples, the link-layer discovery protocol is LLDP. Typically, LLDP communication information includes an Ethernet frame, which is a communication structure that includes multiple data fields in the format and order specified by the LLDP protocol, including, for example, an address field (e.g., destination address, source address), followed by multiple mandatory TLVs (such as chassis ID TLV, port ID TLV, etc.), and then (optionally) so-called optional TLVs. A preamble, end field, and other encapsulated data may also be included. Some optional TLVs can be defined according to industry standards, such as IEEE 802.1AB, while others can be so-called custom TLVs, which can be manufacturer-specific. In some examples, the Alt_Pwr field is a new optional TLV for LLDP frames (which can be a standard-defined optional TLV or a manufacturer-specific custom TLV). In other examples, the link layer discovery protocol is Cisco Discovery Protocol (CDP), Foundry Discovery Protocol (FDP), Nortel Discovery Protocol (NDP), Link Layer Topology Discovery (LLTD), or other similar link layer discovery protocols. Such other link layer discovery protocols also define communication data structures similar to the Ethernet framework described above, which include various data fields similar to the TLVs described above, although the format, naming, and other details of the data structures may vary from one protocol to another. Regardless of the protocol used, the Alt_Pwr field can be added to the communication structure as a new field (if the protocol allows) or by reusing existing fields.

[0031] The control circuit 150 is configured to perform operation 158, which includes setting a power priority for the connected PDs based on whether the connected PDs have an alternative power source, as indicated by the Alt_Pwr field of their link layer protocol communication (as handled in operation 156). The power priority can be used by the control circuit 150 in the manner described above to determine which PDs will continue to receive PoE power via port 140 in the event of a PSE failure.

[0032] Power priorities can include any number of priority levels or tiers, equal to or greater than two. Furthermore, these priority levels can be represented in any way desired. For convenience, this document assumes that power priorities comprise three levels: high, medium, and low (where high is the highest priority and low is the lowest priority). However, those skilled in the art will understand that any other number of levels and any other desired scheme for representing power priorities can be used, such as numerical values, alphanumeric values, color codes, etc. As used herein, a “higher” priority (or similar term) is the priority that makes a PD more likely to be selected as one of the PDs to continue receiving PoE power, and vice versa for a “lower” priority. It is important to note that this meaning of “higher” and “lower” does not necessarily have to relate to high and low in a numerical sense; for example, in some priority schemes, the highest priority might be represented as 1, while in others 1 would be the lowest priority, and in still others, the priority has no numerical value at all.

[0033] In some examples, setting power priorities for connected PDs involves first determining a default power priority for each PD, and then determining an adjusted priority for those PDs with alternative power supplies, where the adjusted priority is a reduction from the default power priority. PDs without alternative power supplies can be assigned their default power priorities. As used herein, "default power priority" is a power priority determined according to a default power priority determination scheme used by PSE 110 to assign power priorities without considering alternative power supplies. One example of a default power priority determination scheme that PSE 110 can use is to allow PDs to request specific power priorities and assign default power priorities to those PDs, which are equal to any power priority requested by the PD. Another default power priority scheme could be, for example, detecting the type of the PD (e.g., information communicated in link layer discovery protocol communications) and assigning a default power priority based on the PD type. For example, control circuitry 150 can consult a specified (predetermined and / or user-configurable) list of PD types with associated priorities to identify the default power priority of a PD; PD types not found in the list can be assigned the power priority specified for the unknown PD type.

[0034] The degree to which the adjusted power priority is reduced relative to the default power priority can vary from one implementation to the next, and in some examples, it can be a user-configurable parameter. In some examples, all PDs with alternative power sources (or, in some instances, all PDs with what are considered sufficient alternative power sources, as further described below) can have their adjusted power priority reduced by a fixed number of tiers (e.g., one tier in some examples) below their default power priority. In some examples, the number of tiers the adjusted priority is reduced relative to the default priority can vary based on one or more factors. For example, the number of tiers the adjusted priority is reduced relative to the default can vary based on the tier of the default priority; for example, if the default priority is high, then the number of tiers reduced can be greater. In other examples, the amount by which the power priority of a given PD is reduced from its default priority can vary from one PD to another based on the characteristics of the PD and / or the type of alternative power sources the PD has. For example, a PD with a power source considered more reliable (such as a local power supply coupled to the mains power supply) can have its power priority reduced more than a PD with a power source considered somewhat less reliable (such as a backup battery).

[0035] In other examples, setting power priorities for connected PDs based on whether they have backup power supplies involves assigning a specified (e.g., predetermined or user-configurable) priority to all PDs with backup power supplies, which may be lower than the highest power priority. For example, all PDs with backup power supplies (or in some cases considered to have sufficient backup power supplies, as described below) may be set to a low power priority. Other PDs that do not have backup power supplies (or have insufficient backup power supplies) may use the default power priority scheme described above to set their power priorities.

[0036] In some examples, the above-described process related to adjusting the power priority of a PD is performed in response to the PD being connected to the PSE110. The PD may send initial link-layer discovery protocol communication as part of the discovery process, and this may trigger the execution of the power priority allocation process for that PD. In other examples, the above-described process for allocating power priorities may be initiated in response to some other conditions. That is, a default power priority may be applied to all PDs until the specified conditions are met, so some PDs may adjust their power priorities as described above. For example, the power priority allocation process may be initiated in response to the current power demand of the PSE110 rising above a predetermined and / or user-configurable threshold (such as 85% of available power). Therefore, when several PDs are currently coupled to the PSE110 and the power demand is below the threshold, the above-described power priority adjustment may be temporarily suspended. Then, as more PDs are coupled to the PSE110 (or as the current PD demand increases) and the threshold is crossed, the PSE110 may adjust the priority of PDs with alternative power supplies as described above.

[0037] Once the power priorities of the PDs have been assigned, the control circuitry 150 of the PSE 110 can respond to a power failure event in the manner described above. That is, if a power failure event is detected (i.e., power demand exceeds available power), the control circuitry 150 will select a first group of PDs from which the PSE will continue to supply PoE power and a second group of PDs from which the PSE will stop supplying PoE power. The first group includes PDs with higher power priorities, and the second group includes PDs with lower power priorities relative to the other PDs. The control circuitry 150 can seek to maximize the number of PDs in the first group that will continue to receive PoE power while keeping the power demand at or below available power. For example, the control circuitry 150 can select n highest priority PDs to continue receiving PoE power, where n is the maximum number that makes the power demand equal to or below available power. Alternatively, equivalently, the control circuitry 150 can identify p lowest priority PDs to stop supplying PoE power, where p is the minimum number that makes the power demand equal to or below available power. If there are more highest-priority PDs than can be included in the first group (e.g., including all of them would exceed available power), then one or more of the highest-priority PDs will be excluded from the first group. Conversely, if there is still additional power headroom after adding all the highest-priority PDs, then control circuitry 150 can consider the next highest-priority level and continue selecting PDs with that priority until the number of PDs in the first group is maximized while keeping power demand at or below available power. When control circuitry 150 needs to select between two PDs with the same power priority, control circuitry 150 can use any desired method to select either PD, such as by prioritizing the PD without an alternative power supply. To stop supplying PoE power to the PDs in the second group, control circuitry 150 can disable PoE power supply to the ports 140 connected to these PDs (note, however, data communication can still continue to flow through these ports as if they were standard Ethernet ports).

[0038] In addition to the operations described above, in some examples the control circuit 150 of PSE 110 can be configured to perform the following operations. Figure 4-6 Any operation related to methods 400, 500, 600 and / or 900. Figure 3 The document also clarifies certain aspects of the PSE 110, describing the PoE systems in which the PSE 110 can be deployed. Figure 3 In Figure 2 The description follows the description above.

[0039] Turn now Figure 2 This will describe the PD used in the PoE system, in the form of PD 200. Figure 2 This is a conceptual block diagram illustrating the PD 200. It should be understood that... Figure 2 It is not intended to show a specific shape, size or other structural details accurately or to scale, and embodiments of PD 200 may have different numbers and arrangements of the components shown and may also include other parts not shown.

[0040] like Figure 2 As shown, PD 200 includes control circuitry 270 and one or more ports 271. PD 200 may also optionally include an alternative power supply 202. PD 200 can be any PoE-enabled electronic device, such as a network device (e.g., a wireless access point), IP phone, IP security camera, laptop, computer monitor, kiosk, sensor, other IoT device, or any other PoE-enabled electronic device.

[0041] Port 271 includes a PoE-enabled port, which may include an RJ45 jack. Each port 271 is configured to receive a connector for an Ethernet cable, which may include an RJ45 connector. This allows the PD 200 to be coupled to a PSE, such as the PSE110 described above. Port 271 is configured to receive PoE power and supply power to other components of the PD 200. Port 271 is also communicatively coupled to control circuitry 270 to communicate data between control circuitry 270 and another device (such as a PSE) connected to port 271. Figure 2 The diagram shows two ports 271, but a PD 200 may include any number of ports 271, equal to or greater than one. Some PD 200s have only one port 271. Others may have two ports 271 to allow the PD to be coupled to multiple network devices (e.g., multiple PSEs), for example, to provide redundancy. A PD 200 may also have more than two ports 271. As mentioned above, PoE ports are familiar to those skilled in the art, therefore, port 271 will not be described in more detail herein.

[0042] Control circuitry 270 includes circuitry configured (e.g., programmed) to perform operations 272 and 274. Control circuitry 270 includes a processor and a storage medium storing instructions executable by the processor to cause operations 272 and 274 to be performed, dedicated hardware configured to perform operations 272 and 274, or some combination of these components. In this document, the processor and dedicated hardware may include any of the examples discussed above relating to control circuitry 150. In some examples, control circuitry 270 may be configured to control other operations of PD 200 besides operations 272 and 274, such as operations controlling communication between PD 200 and PSE (which can share commonalities in all types of PD 200) and other operations that may be more specific to the functionality of various types of PD 200. Since PD 200 can be any of a variety of devices with widely varying functionality, the other operations performed by control circuitry 270 can vary from device to device. These other operations of the PD are familiar to those skilled in the art and are not described herein.

[0043] Operation 272 includes determining whether PD 200 has an existing / available alternative power source 202. Alternative power source 202 is optional, and some instances of PD 200 may have an alternative power source 202 while others may not. Regardless of whether PD 200 has an alternative power source 202, PD 200 is configured to perform operation 272 to check whether it has an alternative power source 202. As used herein, PD 200 has an alternative power source 202, or the alternative power source 202 is "existing" or "available," if the alternative power source 202 is in a state where it can supply power to PD 200. This contrasts with having only components that could potentially provide power but are not currently able to do so. For example, PD 200 with a power cord plugged into a mains power supply can determine that this is an existing / available alternative power source 202, but if the power cord is unplugged from any power source, PD 200 can determine that the power cord is not an alternative power source. Alternate power source 202 does not need to be currently supplying power to PD 200 for PD 200 to consider alternative power source 202 to be present / available, but the power source should be in an energetic state and able to supply power when requested. Examples of alternative power sources include batteries (whether integrated into PD 200 or as an external device plugged into PD 200), local power supplies (e.g., power cords, adapters, or chargers plugged into a power source (e.g., mains power), wireless chargers, or any other external power source (other than PoE power from PSEs). In some examples, if PD 200 has two PoE connections to two different PSEs, PD 200 can also determine that this constitutes alternative power source 202 (i.e., one PSE will be considered an alternative power source relative to the other PSE, and vice versa), provided that both connections are configured to supply PoE power to PD 200; however, if one of the PSEs is configured to supply data only to PD 200, PD 200 can determine that it does not have alternative power source 202.

[0044] Control circuitry 270 can detect the availability of an alternative power source in any of a variety of ways. For example, due to their design, some PDs 200 may not be able to have any alternative power source 202 other than having multiple PoE connections (in an example where they could be considered alternative power sources). This could be the case, for example, because the PD has no power receiving components other than port 271, such as a battery, power cord, power socket, or similar components. In such a PD, control circuitry 270 can be programmed (e.g., during manufacturing or configuration) to automatically identify that it does not have an alternative power source, or in an example where PoE connections to multiple PSEs are considered alternative power sources, control circuitry 270 can also be programmed to check this. In particular, in an example where PoE connections to multiple PSEs are considered alternative power sources, PD 200 can know this via PoE circuitry included in PD 200 to manage PoE port 271, which can be part of control circuitry 270 or a separate circuitry that control circuitry 270 can communicate with to determine the presence of multiple PoE connections. In other PDs 200 that do indeed have one or more components that may be allowed as alternative power sources (e.g., batteries, power plugs, power jacks, wireless charging circuitry, etc.), power management / budgeting circuitry (not shown) may be provided to monitor and / or control the power supplied from these sources, and control circuitry 270 may be configured to query such power management circuitry to determine whether alternative power source 202 is currently enabled and capable of providing power; if so, it is identified as an existing / available alternative power source 202, and if not, it is not identified as an available / existing alternative power source 202. Such power management / budgeting circuitry is typically included in any PD having power receiving components (such as batteries, power cords, etc.) to monitor and control the power flow from or through these components, and is well known to those skilled in the art. Optionally, or additionally, control circuitry 270 may be configured to directly sense the presence of power from alternative power source 202, for example, via a sensor (not shown) such as a current sensor coupled to a system power bus or other power line receiving power from alternative power source 202. As another example, the PD 200, which has (or is configured to receive) a battery, will also be provided with a battery charging / management circuit, and the control circuit 270 can query the battery charging / management circuit to determine whether a battery is installed and, if so, what the battery's state of charge is.

[0045] Operation 274 includes sending link-layer protocol communication to the PSE, which includes an Alt_Pwr field indicating whether the PD has an alternative power supply. In some examples, both the PD 200 with and without an alternative power supply 202 include the Alt_Pwr field in its link-layer protocol communication, with the PD 200 without an alternative power supply 202 indicating this in the Alt_Pwr field. In other examples, the PD 200 without an alternative power supply 202 may omit or send a blank Alt_Pwr field to indicate that it does not have an alternative power supply 202. In some examples, the link-layer discovery protocol is LLDP and the Alt_Pwr field is a TLV (by manufacturer or by standard) defined for the LLDP Ethernet framework for communicating whether the PD has an alternative power supply. In other examples, the link-layer discovery protocol is CDP, Foundry Discovery Protocol (FDP), Nortel Discovery Protocol (NDP), Link Layer Topology Discovery (LLTD), or other similar link-layer discovery protocols, and in any of these examples, the Alt_Pwr field may include a new field for communication added to one of these protocols. In some examples, link-layer protocol communication sent by PD 200 may be communication sent by PD 200 during discovery operations, such as when PD 200 is first inserted into PSE (or when communication is resumed after a failure) and PD 200 is identifying itself to PSE. Link-layer protocol communication can serve multiple purposes, such as providing discovery information about PD 200 to PSE in addition to the information contained in the Alt_Pwr field. Link-layer protocol communication may be sent more than once. For example, it may be sent during the initial connection of PD 200 to PSE 110 and / or periodically sent at specified time intervals thereafter. In addition, in some examples, the PD 200 can send communications in response to the detection of specific conditions, such as a change in the state of its backup power supply.

[0046] In some examples, the control circuit 270 may also include information identifying the type of alternative power source in the Alt_Pwr field. In some examples, if the alternative power source is a battery, the control circuit 270 may also include information about the battery's state of charge in the Alt_Pwr field, such as the charge level, the estimated battery runtime, or any other information related to the amount of charge stored in the battery.

[0047] Now go to Figure 3 The PoE system is described in the form of System 100. System 100 includes the PSE 110 described above. System 100 also includes several different instances of the PD 200 described above. Certain aspects of the PSE 110 and PD 200 described above... Figure 3Not shown in the image. Furthermore, it has been combined with... Figure 1 and Figure 2 Description Figure 3 Descriptions of certain aspects shown may be omitted below.

[0048] like Figure 3 As shown, PD 200 is coupled to PSE 110. In Figure 3 Three PD 200s are shown, labeled PD_1, PD_2, and PD_N. However, it should be understood that any number of PD 200s from 1 to N can be coupled to the PSE 110, where N is the number of ports 140 of the PSE 110 (N equals or greater than 2). The PD 200s are communicatively coupled to the PSE 110 via their respective Ethernet cables 210, which are plugged into ports 140 of the PSE 110 and ports 271 of the PD 200s.

[0049] like Figure 3 As shown, each of the PDs 200 sends a link-layer protocol communication 160 to the PSE 110 (e.g., as part of the discovery process). PD 200 labeled PD_1 sends communication 160_1, PD_2 sends communication 160_2, and so on up to PD_N sending communication 160_N. Each of the communications 160 includes a series of fields as defined by the link-layer discovery protocol, including the Alt_Pwr field 161. For example, in Figure 3 In the diagram, communication 160 is shown as including a destination address field labeled DST, a source address field labeled SRC, and an Alt_Pwr field 161. It should be understood that communication may include several other fields, which are not shown herein for clarity. The Alt_Pwr field 161 indicates whether the corresponding PD 200 sending the communication has an alternative power supply 202. Figure 3In the examples, PDs 200 labeled PD_1 and PD_2 have alternative power sources 202 (in the form of a battery and a power adapter, respectively), so the Alt_Pwr field 161 in communications 160_1 and 160_2 indicates "yes" (i.e., alternative power source 202 is present). On the other hand, PD 200 labeled PD_N does not have an alternative power source, so the Alt_Pwr field 161 in communications 160_N indicates "no". The values ​​of communications 160 are shown in text (such as "yes" or "no") in the diagram for ease of understanding, but in practice the actual values ​​can be encoded in a machine-readable format such as binary. Furthermore, in some examples, the Alt_Pwr field 161 can communicate information about the power source 202 when it is present, such as the type of power source and its charging state (in the case of a battery). Therefore, in some examples, communications 160_1 can also indicate that the power source 202 of PD_1 is a battery and its charging state (in the case of a battery). Figure 3 In this context, this is expressed as the amount of time the PD can operate, but it can be expressed in other terms, such as raw charge amount (watts per hour), percentage of total charge, etc., and communication 160_2 can also indicate that the power supply 202 of the PD_2 is a local power supply connected to the main power supply (e.g., via a power adapter).

[0050] PSE 110 receives communication 160 and can determine power priority based on the Alt_Pwr field 161 therein. For example, as shown in Table 151, control circuitry 150 can record which PDs 200 have an alternative power supply 202, as indicated by the Alt_Pwr field 161 of communication 160. Control circuitry 150 knows which communication information 160 comes from which PD 200 because of which corresponding port 140 the communication was received on and / or because of the SRC field (in an example where such a field is provided in communication 160). As described above, control circuitry 150 can also determine a default power priority for each PD. Assumptive values ​​for the default power priority of PDs 200 are shown in Table 151. Based on the default power priority and whether a PD 200 has an alternative power supply 202, control circuitry 150 can determine an assigned priority for the PD 200. As described above, for those PDs 200 with an alternative power supply 202, the assigned power priority can be adjusted relative to the default power priority (e.g., reduced). Figure 3In the example shown, the adjusted power priority of PD 200 with alternative power supply 202 is reduced by one level relative to the default power priority of PD 200. Therefore, as shown in Table 151, since PDs 200 labeled PD_1 and PD_2 have alternative power supply 202, control circuit 150 can reduce their power priority so that PD_1 is assigned a low power priority (adjusted down from its intermediate default power priority) and PD_2 is assigned a medium power priority (adjusted down from its high default power priority). On the other hand, since PD_N does not have alternative power supply 202, its assigned power priority remains the same as its default power priority, which is high in this example. (As used herein, "adjusted power priority" refers to the assigned power priority that has been adjusted relative to the default power priority). In some examples, control circuit 150 may store some or all of the above information in a data structure such as Table 151. In other examples, control circuitry 150 may determine or use this information as needed and may store some or all of it, but not necessarily in the same data structure or in the same format as shown in Table 151. In some examples, additional information, such as the type of power supply, charging status, etc., may also be stored.

[0051] In some examples, the system can maintain a record of the default power priorities for all PDs, including PDs whose power priorities have already been adjusted. The PSE 110 can periodically revisit the power priority assignments and can determine that a given PD 200 should have its power priority reset to its default value. Therefore, having a record of the default power priorities for all PDs 200 facilitates this power priority reset. For example, the power priority can be reset in response to an event that negatively impacts the ability of a backup power source to supply power to the PD 200. Such events could include, for example, a battery state of charge dropping below a threshold, a reduced output power of a secondary PoE connection to another PSE, a local power supply being unplugged or failing, or other similar events that might affect the backup power source's ability to provide power. In some examples, these events can be communicated to the PSE 110 via the Alt_Pwr field of link layer protocol communication. For example, link layer protocol communication can periodically be sent from the PD 200 to the PSE 110, and the PD 220 can include status updates regarding its backup power source in these communications.

[0052] Continue to refer to Figure 3Suppose a power failure event occurs, and the PSE 110 is only able to supply power to a subset of PDs 200. In this case, the control circuit 150 of the PSE 110 can select a subset of PDs 200 from those PDs with the highest priority to continue supplying PoE power to them, and can stop supplying PoE power to the remaining PDs 200. Because the priority of PDs_1 and PD_2 is reduced after allocation, they are less likely to be selected to continue receiving PoE power, while PD_N will be more likely to be selected to receive PoE power.

[0053] For example, if we assume that only PD_1, PD_2, and PD_N are present and only one PD 200 can be supplied with PoE power, then PD_N will be selected to continue receiving PoE power because it has the highest priority (highest priority) among the three connected PD 200s. Therefore, all three PD 200s will remain powered, with PD_N receiving PoE power while PD_1 and PD_2 are powered by their backup power source 202. Conversely, if we consider the same scenario but without adjusting the power priority, there is a risk that PD_2 might be selected instead of PD_N to receive PoE power (since both PD_2 and PD_N have a high default power priority), and in this case, PD_N would be de-energized. Therefore, adjusting the power priority of the PD 200s with backup power source 202 can increase the number of PD 200s that can remain powered during a PSE power failure, relative to the scenario where the power priority remains at its default value.

[0054] Now go to Figure 4 , 5 Sections 6, 7, and 9 will describe example methods 400, 500, 600, and 900. For example, methods 400, 500, 600, and 900 can be executed by a PSE, such as the PSE 110 described above. In particular, in some examples, methods 400, 500, 600, and / or 900 can be executed by control circuitry 150 of the PSE 110. In some examples, control circuitry 150 includes a computer-readable storage medium storing instructions corresponding to the operations of methods 400, 500, and / or 600, i.e., instructions configured to cause the PSE 110 to execute methods 400, 500, 600, and / or 900 when executed by a processor of control circuitry 150. In some examples, control circuitry 150 includes dedicated hardware configured to execute methods 400, 500, 600, and / or 900. In some examples, the control circuit 150 is configured to execute methods 400, 500, 600 and / or 900 by a combination of a processor that executes instructions and dedicated hardware.

[0055] like Figure 4As shown, method 400 includes operations of blocks 402, 404, 406, 408 and 410, which will be described in more detail below.

[0056] In block 402, the PSE determines a default power priority for each connected PD. The default power priority is the power priority to be allocated to each PD using a default power priority allocation scheme, such as assigning each PD the power priority requested by that PD. The default power priority corresponds to the power priority to be allocated to each PD without considering alternative power sources, i.e., if it is assumed that each PD has no alternative power source. Although shown first for ease of description, block 402 does not necessarily have to be executed first; for example, block 402 can be executed at any time before block 408, or concurrently with block 408.

[0057] In block 404, the PSE receives link-layer protocol communication, including the Alt_Pwr field, from the connected PD. In some examples, the communication received in block 404 may be part of a discovery process that occurs when the PD first connects to the PSE (or reconnects after a disconnection or failure event). In other examples, the communication received in block 404 may be subsequent communication; for example, the PD may periodically send link-layer discovery protocol communication to the PSE, and block 404 may include such communication.

[0058] In block 406, the PSE determines whether the Alt_Pwr field indicates that the PD transmitting the communication has an alternative power source. If the Alt_Pwr field indicates that the PD does have power (block 406 determines = yes), the method continues to block 408. If the Alt_Pwr field indicates that the PD does not have power (block 406 determines = no), the method continues to block 410.

[0059] In block 408, the PSE lowers the power priority of the PD relative to the default power priority determined in block 402. In other words, the PSE determines an adjusted priority for the PD that is lower than the default priority and assigns the adjusted priority as the PD's power priority.

[0060] In block 410, the PSE uses the default priority determined in block 402 as the power priority of the PD. In other words, the power priority assigned to the PD is equal to the default power priority.

[0061] In some examples, blocks 404 to 410 can be repeated for each PD coupled to the PSE until all PDs have been assigned power priority.

[0062] In some examples, blocks 406 and / or 408 can be executed directly after block 404. In other examples, after block 404 is completed, the PSE can wait to execute blocks 406 and / or 408 until some other condition is met. For example, in some implementations, the aforementioned condition could be that the system's current power demand exceeds (or equals) certain threshold amounts (which may be predetermined or user-configurable). In implementations where blocks 406 and / or 408 are delayed until another condition is met, during this period the PD can be assigned its respective default power priority, as determined in block 402, and then when blocks 406 and 408 are finally executed, the power priorities determined in these blocks can override the initially assigned power priorities.

[0063] like Figure 5 As shown, method 500 includes operations of blocks 502, 504, 506, 507, 508, and 510. The method may also optionally include the operation of block 514. Method 500 includes modifications to method 400. In particular, the operations of blocks 502, 504, 506, 508, and 510 may be similar to the operations of blocks 402, 404, 406, 408, and 410 described above, but method 500 differs from method 400 in that block 507 is added between blocks 506 and 508, and block 514 is added (optionally) after block 508.

[0064] In block 502, the PSE determines the default power priority for each connected PD. Although block 502 is shown first for ease of description, it is not necessary to execute block 502 first; for example, block 502 can be executed at any time before block 508, or concurrently with block 508.

[0065] In block 504, the PSE receives link-layer protocol communication, including the Alt_Pwr field, from the connected PD. As mentioned above, this communication can be part of the initial discovery process or subsequent communication.

[0066] In block 506, the PSE determines whether the Alt_Pwr field indicates that the PD transmitting the communication has an alternative power source. If the Alt_Pwr field indicates that the PD does have power (Block 506 determines = Yes), the method continues to block 512. If the Alt_Pwr field indicates that the PD does not have power (Block 506 determines = No), the method continues to block 510.

[0067] In block 507, the PSE determines whether the PD has sufficient alternative power sources, as indicated in the Alt_Pwr field. In some examples, determining whether alternative power sources are sufficient includes determining the type of alternative power source. In particular, in these examples, the Alt_Pwr field can indicate not only whether the PD has alternative power sources, but also the type of alternative power source. In some examples, the types of alternative power sources that can be indicated by the Alt_Pwr field include: batteries, local power supplies connected to an external power source (e.g., mains power) via a power cord, power adapters, or similar items, and another PoE connection to another PSE (other than the PSE performing method 500). In some examples, the type of power source can be indicated with even greater granularity than those mentioned above; for example, different subtypes of local power supplies can be identified as different types, such as power cords, adapters, wireless chargers, etc. In some examples, once the PSE knows the type of alternative power source, the PSE can determine whether the alternative power source is sufficient based on the type, for example by consulting a specified (predetermined and / or user-configurable) list of types of alternative power sources considered sufficient.

[0068] In some examples, determining whether an alternative power source is sufficient, as a supplement to or alternative to determining the type of alternative power source, may include determining whether the power supplied by the source is sufficient. In such examples, the Alt_Pwr field may indicate the power supplied by the alternative power source. The supplied power may be compared to a predetermined threshold, and if the supplied power exceeds that threshold, the alternative power source may be sufficient. The threshold may be a generic threshold that is the same for all PDs (e.g., equal to the maximum output power per port of the PSE or some other predetermined or user-configurable value), or the threshold may vary from one PD to the next based on its power demand, which the PD may communicate its power demand to the PSE during or after discovery. In some examples, certain types of alternative power sources may be assumed to be sufficient, such as a main power connection, and in such cases, the indication of supplied power may be ignored; however, for power types that may be sufficient sometimes and insufficient sometimes (e.g., another PoE connection), the above-described operation of comparing the supplied power to a threshold may be performed. See below. Figure 6 An example describing in more detail how to determine if the backup power supply is sufficient.

[0069] If the alternative power supply is sufficient (block 507 OK = Yes), the method continues to block 508. If the alternative power supply is insufficient (block 507 OK = No), the method continues to block 510.

[0070] In block 508, PSE lowers the power priority of PD relative to the default power priority determined in block 502.

[0071] In block 510, the PSE uses the default priority determined in block 502 as the power priority of the PD.

[0072] In some examples, blocks 504 to 510 can be repeated for each PD coupled to the PSE until all PDs have been assigned power priority.

[0073] In some examples, method 500 may optionally include the additional operation of block 514. In block 514, the PSE may begin negotiating with the PD to stop supplying PoE power to that PD. This can constitute a proactive disablement of PoE power to the PD, which is separate and independent from any PSE power failure event. In some cases, this may allow for the prevention of PSE power failures in advance, rather than waiting for a failure to occur and then reacting to it. In some examples, the PSE simply requests the PD to accept the PoE power supply stoppage, but the PD may refuse this request (unlike when a PSE failure event occurs, in which case the PSE decides for itself which PDs to continue supplying PoE power to and which to cut off). In some examples, the negotiation in block 514 may be performed in response to the alternative power source being a member of some power source list (e.g., the same power source list mentioned in block 507 above, or a different list). In other words, in some examples, such negotiation is performed only for PDs with certain types of alternative power sources. In other examples, negotiation may be performed for any PD identified in block 506 as having sufficient power. In other examples, block 514 is ignored. In some examples, as shown in the figure, block 514 is executed after block 508, but in other examples, block 514 can be executed between block 507 and block 508 or concurrently with block 508.

[0074] As noted above regarding blocks 406 and 408 of method 400, in some examples, blocks 506-514 can be executed directly in response to block 504 without waiting for another condition to be met, or in other examples, the execution of some or all of blocks 506-514 can be postponed until another condition is met (such as, for example, power demand exceeding a threshold).

[0075] like Figure 6 As shown, method 600 includes operations in blocks 602, 604, 606, 608, 610, and 612. Method 600 can be used in block 507 of method 500 as an example of how to determine whether the alternative power supply is sufficient.

[0076] In block 602, the PSE determines the type of alternative power source indicated in the Alt_Pwr field.

[0077] In block 604, the PSE determines whether the alternative power source is a battery. If the alternative power source is a battery (block 604 determines = yes), the method continues to block 606. If the alternative power source is not a battery (block 604 determines = no), the method continues to block 610.

[0078] In block 606, the PSE determines whether the battery's state of charge (indicated by the Alt_Pwr field) meets a threshold (e.g., exceeds the threshold in some examples, or equals / exceeds the threshold in some examples). The state of charge can be identified as the raw amount of charge (e.g., watts per hour), a percentage of full charge, an estimated runtime of the PD on the battery, or any other convenient metric used to measure or describe the amount of charge in the battery. The threshold can be a predetermined value, a user-configurable value, or both (e.g., the threshold can start at a predetermined value that the user can then change). If the state of charge meets the threshold (block 606 determines = Yes), the method continues to block 608. If the state of charge does not meet the threshold (block 606 determines = No), the method continues to block 612.

[0079] In block 608, the PSE identifies the alternative power supply as sufficient.

[0080] In block 610, the PSE determines whether the type of alternative power source (as indicated by the Alt_Pwr field) is found in the list of approved alternative power sources. The list of approved power sources may include, for example, power sources considered reliable and / or capable of fully powering the PD, such as local power supplies connected to the mains power source (e.g., via power cord, adapter, wireless charger, etc.). The list of approved power sources may be predetermined (e.g., specified by the manufacturer) and / or user-configurable. If the type of alternative power source is found in the list (Block 610 Determines = Yes), the method proceeds to block 608. If the type of alternative power source is not found in the list (Block 610 Determines = No), the method proceeds to block 612.

[0081] In block 608, the PSE identifies the alternative power supply as insufficient.

[0082] Therefore, method 600 identifies the following as sufficient: (a) a battery with a sufficient state of charge (block 604→606→608), or (b) another type of power source found in the list of approved power sources (block 604→610→608). On the other hand, method 600 identifies the following as insufficient: (c) a battery with an insufficient state of charge (block 604→606→612), or (d) another type of power source not found in the list of approved power sources (block 604→610→612).

[0083] Turn now Figure 7This document describes an example non-transitory computer-readable storage medium 700 (storage medium 700). Storage medium 700 stores instructions 756 and 758, which can be executed by a processor of a PSE (e.g., a processor of control circuitry 150 of PSE 110) to cause the PSE to perform the various operations described herein. In some examples, storage medium 700 is part of a PSE, such as PSE 110. For example, in some embodiments, storage medium 700 is part of control circuitry 150, and control circuitry 150 also includes a processor coupled to storage medium 700 and configured to read and execute instructions 756 and 758. In some embodiments, storage medium 700 may be provided as a computer program product that is at least initially independent of the PSE. The computer program product can be used to program the PSE to perform operations associated with instructions 756 and 758, for example, by transferring instructions 756 and 758 from storage medium 700 to the PSE, or for copying to local memory on the PSE, or for immediate execution by the PSE.

[0084] Instruction 756 includes instructions for monitoring link-layer protocol communication from a connected PD, including an Alt_Pwr field indicating whether the PD has an alternative power source. For example, instruction 756 may include instructions for performing operation 156 and other associated operations related to PSE 110 as described above. Instruction 756 may also include the operations related to blocks 404 and 504 of methods 400 and 500 as described above.

[0085] Instruction 758 includes instructions for setting power priority for the connected PD based on whether it has an alternative power source (as indicated by the Alt_Pwr field). For example, instruction 758 may include instructions for performing the operations 158 and other associated operations described above in relation to PSE 110. Instruction 758 may also include the operations described above in relation to blocks 402, 406, 408 and 410 of method 400, blocks 502, 506, 507, 508 and 510 of method 500, and / or blocks 602 to 612 of method 600.

[0086] Now go to Figure 8This document describes an example non-transitory computer-readable storage medium 800 (storage medium 800). Storage medium 800 stores instructions 872 and 874, which can be executed by a processor of a PD (e.g., the processor of control circuitry 270 of PD 200) to cause the PD to perform various operations described herein. In some examples, storage medium 800 is part of a PD, such as PD 200. For example, in some embodiments, storage medium 800 is part of control circuitry 270, and control circuitry 270 also includes a processor coupled to storage medium 800 and configured to read and execute instructions 872 and 874. In some embodiments, storage medium 800 may be provided as a computer program product that is at least initially independent of the PD. The computer program product can be used to program the PD to perform operations associated with instructions 872 and 874, for example, by transferring instructions 872 and 874 from storage medium 800 to the PD for copying to local storage on the PD or for immediate execution by the PD.

[0087] Instruction 872 includes instructions to determine whether the PD has an available alternative power source. Instruction 872 may include instructions to perform the aforementioned operation 272 related to the PD 200 and other associated operations.

[0088] Instruction 874 includes instructions for sending link-layer protocol communication, which includes an alternative power field indicating whether the PD has an alternative power source. Instruction 874 may include instructions for performing the aforementioned operation 274 related to the PD 200 and other associated operations.

[0089] like Figure 9 As shown, method 900 includes the operations of blocks 902, 904 and 906.

[0090] In block 902, the PSE sets power priorities for the PDs coupled thereto according to any of the methods described above (e.g., by performing method 400 or 600), including determining a default power priority for each PD and also determining an adjusted power priority for PDs with alternative power supplies. The PSE may store the default power priorities for all PDs, including PDs assigned adjusted power priorities.

[0091] In block 904, the PSE detects a change in the state of the system. In some embodiments, the change in state can be a change affecting one or more alternative power sources in the PD. For example, in some embodiments, the change in state includes a degradation in the ability of an alternative power source to adequately power a given PD. In some embodiments, such a change in state can include a battery charge level falling below a minimum threshold (which may be predetermined or user-configurable and may be the same as or different from the threshold mentioned in block 606 of method 600), a battery discharge rate exceeding another threshold, and / or some other battery fault state (e.g., battery temperature exceeding a specified operating range, battery being removed or otherwise unable to supply power, etc.). In some embodiments, such a change in state can include a local power supply becoming unable to supply power (e.g., due to being removed or some other fault), or a reduction in the amount of power supplied by the local power supply. In some embodiments, such a change in state can include a secondary PoE connection to another PSE ceasing to supply power or reducing the amount of power supplied. This change in the state of the PD's backup power supply can be communicated to the PSE, for example via the Alt_Pwr field of the Link Layer Discovery Protocol (PLC). The PD can periodically send and / or send PSC communications in response to events detected by the PD. In other examples, the change in system state can be some other change in the system's state. For example, an administrator can put the PSE into a specified mode, which is considered a state change.

[0092] In block 906, in response to the detection in block 904, the PSE can reset the power priorities of one or more PDs that were previously assigned adjusted power priorities in block 902 to their respective default power priorities. In some examples, when the state change detected in block 904 is a degradation of the power supply capability of a PD's alternative power source, only the PD (or PDs) experiencing the state change resets its power priority to the default, while the other PDs can retain their adjusted power priorities. In other examples, all PDs can reset their power priorities to their default power priorities.

[0093] The above describes various types of electronic circuits. As used herein, “electronic” is intended to be broadly understood to include all types of circuits that utilize electricity, including digital and analog circuits, direct current (DC) and alternating current (AC) circuits, as well as circuits that convert electricity into another form of energy and circuits that use electricity to perform other functions. In other words, there is no distinction between “electronic” circuits and “electrical” circuits as used herein.

[0094] It should be understood that both the general description and the detailed description provide illustrative examples and are intended to provide an understanding of this disclosure without limiting its scope. Various mechanical, compositional, structural, electronic, and operational changes may be made without departing from the scope of this specification and the claims. In some instances, well-known circuits, structures, and techniques have not been shown or described in detail to avoid obscuring the examples. Similar numerals in two or more figures denote identical or similar elements.

[0095] Furthermore, the singular forms “a,” “an,” and “the” are also intended to include the plural forms, unless the context otherwise requires. Additionally, the terms “comprises,” “comprising,” “includes,” and similar terms specify the presence of the stated feature, step, operation, element, and / or component but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups. Components described as coupled may be directly coupled electronically or mechanically, or indirectly coupled via one or more intermediate components, unless otherwise specified. Mathematical and geometric terms need not be used according to their strict definitions unless otherwise specified in the context of the description, as it will be understood by those skilled in the art that, for example, fundamentally similar elements operating in a fundamentally similar manner may readily fall within the scope of descriptive terms, even though the terms also have strict definitions.

[0096] And / or: Sometimes the phrase "and / or" is used in this article with a list of items. The phrase means that any combination of items in the list can be included—from a single item to all items and any permutation in between. Thus, for example, "A, B, and / or C" means "one of {A}, {B}, {C}, {A, B}, {A, C}, {C, B}, and {A, C, B}".

[0097] An element and its associated aspects described in detail with reference to an example may be included in other examples, where they are not specifically shown or described, provided that it is practicable. For example, if an element is described in detail with reference to an example but not with reference to a second example, that element may still be referred to as being included in the second example.

[0098] Unless otherwise stated herein or implied by the context, when approximate terms such as “roughly,” “approximately,” “about,” “around,” “roughly,” etc., are used, they should be understood to mean, without requiring mathematical precision, a range of variation that includes, but is not strictly limited to, the value, property, or relationship described herein. In particular, apart from any range explicitly indicated herein (if any), the range of variation implied by the use of such approximate terms includes at least any insignificant variations and typical variations in items of the type described in the relevant art due to manufacturing or other tolerances. In any case, unless otherwise stated, the range of variation may include at least a numerical value within ±1% of the value, property, or relationship described herein.

[0099] Given the disclosure herein, other modifications and alternative examples will be apparent to those skilled in the art. For example, apparatus and methods may include additional components or steps that are omitted in the diagrams and descriptions for clarity of operation. Therefore, this description should be construed as illustrative only and its purpose is to teach those skilled in the art a general manner of implementing the teachings. It should be understood that the various examples shown and described herein should be considered exemplary. Elements and materials shown and described herein, as well as arrangements of such elements and materials, may be substituted, components and processes may be reversed, and certain features of the teachings may be used independently, all of which will be apparent to those skilled in the art upon obtaining the benefits described herein. Changes may be made to the elements described herein without departing from the scope of the teachings and the following claims.

[0100] It should be understood that the specific examples presented herein are non-limiting, and modifications to the structure, dimensions, materials, and methods may be made without departing from the scope of this teaching.

[0101] It will be apparent to those skilled in the art from the description of the invention disclosed herein and other examples of practice based on this disclosure. The description and examples are to be considered exemplary only, and the following claims shall enjoy their fullest extent, including equivalents, under applicable law.

Claims

1. A Power over Ethernet (PoE) power supply device (PSE), comprising: The port, via a corresponding communication link, can be connected to the PoE powered device (PD) to supply power to the PD and exchange communication with the PD; as well as Control circuitry, configured to operate when multiple PDs are connected to the port: Receive link layer protocol communications from the plurality of PDs, wherein each link layer protocol communication includes an alternative power field indicating whether the PD sending the corresponding communication has an alternative power source; as well as The power priority of the plurality of PDs is set at least in part based on the corresponding alternative power field of the communication to reduce the power priority of PDs with alternative power sources.

2. The PSE according to claim 1, The control circuitry includes setting the power priority for the plurality of PDs based at least in part on the corresponding alternative power fields of the communication. Determine default values ​​for the power priorities of the plurality of PDs; and In response to a communication received from a first PD of the plurality of PDs indicating that the first PD has an alternative power source, the power priority of the first PD is set to an adjusted value, which is lower than the default value of the first PD.

3. The PSE according to claim 1, The control circuitry includes setting the power priority for the plurality of PDs based at least in part on the corresponding alternative power fields of the communication. Determine default values ​​for the power priorities of the plurality of PDs; Set the power priority of any of the PDs that do not have alternative power sources as indicated by the alternative power field to their respective default values; as well as The power priority of any PD with alternative power sources, as indicated by the alternative power field, is set to a corresponding adjusted value, which is lower than the corresponding default value of the corresponding PD.

4. The PSE according to claim 1, Setting the power priority for the plurality of PDs based at least in part on the corresponding alternative power field of the communication includes the control circuit reducing the power priority of any PD with an alternative power source as indicated by the alternative power field relative to the corresponding default value.

5. The PSE according to claim 1, Setting the power priority for the plurality of PDs based at least in part on the corresponding alternative power field of the communication includes the control circuit being for each of the PDs having an alternative power source as indicated by the alternative power field: Determine whether the alternative power supply for the PD is sufficient; and In response to determining that the alternative power source for the PD is sufficient, the power priority of the PD is reduced relative to the default value of the power priority of the PD.

6. The PSE according to claim 1, in, Each alternative power field indicating the presence of an alternative power source also indicates the type of the alternative power source.

7. The PSE according to claim 6, The control circuitry is configured to negotiate with the given PD to stop supplying power to the given PD in response to an indication from the alternative power field of a communication received from the given PD that a specific type of alternative power source is available.

8. The PSE according to claim 6, The types of alternative power sources that can be indicated by the alternative power field include: Battery, local power supply and / or connection to a second PSE.

9. The PSE according to claim 8, Each alternative power field indicating that the transmitting PD has a battery also indicates the estimated runtime and / or charge level of the battery.

10. The PSE according to claim 9, The control circuitry is configured to, for each PD having a battery as indicated by the alternative power field, compare the estimated runtime and / or charge level of the battery with a threshold, and: In response to the estimated runtime and / or charge level of the battery being less than the threshold, the power priority of the PD is set to a default value; and In response to the estimated runtime and / or charging level of the battery being greater than the threshold, the power priority of the PD is set to an adjusted value lower than the default value.

11. The PSE according to claim 1, The control circuit is configured to detect changes in the state of the system including the PSE and, in response to detecting the changes in state, reset the power priority of one or more PDs from previously assigned adjusted values ​​to default values.

12. The PSE according to claim 1, The alternative power field includes the time-length-value (TLV) data structure of the data unit of the link layer protocol.

13. A Power over Ethernet (PoE) powered device (PD), comprising: The port is capable of connecting to the PoE power supply device (PSE) via a communication link to receive power from the PSE and exchange communication with the PSE; as well as Control circuitry, configured to operate when the port is connected to the PSE: Determine if there are alternative power sources available for the PD other than the PSE; The link layer protocol communication is sent to the PSE via the port. The link layer protocol communication includes an alternative power field indicating whether the PD has the alternative power source in order to reduce the power priority of the PD with the alternative power source.

14. The PD according to claim 13, The control circuitry is configured to, in response to determining that an alternative power source is available for the PD: Determine the type of the alternative power supply, and The type of the alternative power source is indicated in the alternative power field of the communication.

15. The PD according to claim 14, The types of alternative power sources identified by the control circuit include batteries, local power supplies, and connections to a second PSE.

16. The PD according to claim 15, The control circuitry is configured to, in response to determining that an alternative power source is available for the PD and that the alternative power source is a battery, indicate the estimated runtime and / or charge level of the battery in the alternative power field of the communication.

17. The PD according to claim 13, The link layer protocol mentioned therein is one of the following: Link Layer Discovery Protocol LLDP, Cisco Discovery Protocol CDP, Foundry Discovery Protocol FDP, Nortel Discovery Protocol NDP, or Link Layer Topology Discovery Protocol LLTD.

18. The PD according to claim 13, The alternative power field includes the time-length-value (TLV) data structure of the data unit of the link layer protocol.

19. A system comprising, One or more Power over Ethernet (PoE) powered devices (PDs), each PD including: PD PoE port; and PD control circuit; as well as PoE power supply equipment (PSE) includes: The PSE PoE port can be connected to the corresponding PDPoE port of the PD via a corresponding communication link to supply power to the PD and exchange communication with the PD; and PSE control circuit, The PD control circuit of each PD is configured to send a link layer protocol communication to the PSE when the corresponding PD is connected to one of the PSE PoE ports. The link layer protocol communication includes an alternative power field indicating whether the corresponding PD has an alternative power source. The PSE control circuit is configured such that, when the PD is connected to the PSE PoE port: Receive the link layer protocol communication from the PD; as well as At least in part, the power priority of a PD is set based on whether the PD has a corresponding alternative power source, as indicated by the corresponding alternative power field of the communication, so as to reduce the power priority of PDs with alternative power sources.

20. The system according to claim 19, The link layer protocol mentioned is one of the following: Link Layer Discovery Protocol (LLDP), Cisco Discovery Protocol (CDP), Foundry Discovery Protocol (FDP), Nortel Discovery Protocol (NDP), or Link Layer Topology Discovery Protocol (LLTD); and The alternative power field includes the time-length-value (TLV) data structure of the data unit of the link layer protocol.

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