PoE Power Sourcing Equipment (PSE) Introduction and FAQs

The initially published IEEE802.3af standard has divided Power over Ethernet (PoE) technology into two main power device types: power sourcing equipment (PSE) that provides power on the Ethernet cable and powered device (PD) that accepts the power. To get a better understanding of the PoE network system, it is necessary to get familiar with the PoE devices. This post will focus on the common PoE PSE devices and clarify their applicable scenarios.

What Is PoE PSE?

PoE PSE stands for Power Sourcing Equipment in a Power over Ethernet (PoE) system. It refers to the equipment that provides power to PoE PDs (Powered Devices). PoE PSEs are responsible for detecting and classifying the PoE devices connected to them. They also monitor the power usage and can manage the power allocation to the connected devices based on their power needs.


There are two essential components in a Power over Ethernet (PoE) system: PoE PD (Powered Device) and PoE PSE (Power Sourcing Equipment). Here’s a brief explanation of the difference between them:

  • PoE PSE (Power Sourcing Equipment): A PoE PSE refers to the equipment that provides power to PoE PDs. It can be a PoE switch or a PoE injector. The PoE PSE injects power into the Ethernet cable along with the data signals, allowing the connected PoE PDs to receive both data and power through a single cable. It acts as the power source for PoE devices.
  • PoE PD (Powered Device): A PoE PD refers to the device that receives power from the PoE network infrastructure. It can be various types of devices, such as IP phones, wireless access points, IP cameras, and network switches. The PoE PD consumes power from the PoE PSE to operate without requiring a separate power source. It typically has an Ethernet input for data communication and power input to receive power from the PoE PSE.

Common PoE PSE Introduction

The PoE PSE (Power Sourcing Equipment) plays a critical role in delivering power to PoE-enabled devices within the network. However, the range of available PoE PSE devices is relatively more limited compared to the multitude of PoE PDs. The primary PoE PSE types commonly deployed in modern PoE networks include PoE switches, PoE injectors, PoE NVRs, and PoE media converters. Here is the introduction to the common PoE PSE devices:

PoE PSE Devices
  • PoE Switch: PoE network switch is a network switch that has PoE injection built-in. Therefore, it can transmit both data and power over one Ethernet cable to the PD directly connected to it.
  • PoE Injector: For adding PoE to regular non-PoE network links, a PoE injector is used. It injects power to data that is coming from a non-PoE switch and delivers both the power and data to the PD through an Ethernet cable.
  • PoE NVR: PoE NVR(network video recorder) has PoE injection built-in. Mostly used in the IP video surveillance system, it is responsible for encoding and processing the video data on IP video cameras, and recording it for storage and remote viewing. PoE NVR can also deliver power to IP video cameras through Ethernet cables.
  • PoE Media ConverterPoE media converter is a device that not only connects fiber cabling to a copper network but also provides PoE power to PoE PD such as IP cameras and VoIP phones.
  • PoE SplitterThe PoE splitter can also supply power, but it delivers power to a non-PoE terminal device by splitting power from the data and feeding it to the non-PoE device through its power supply cable. It is used for deploying remote non-PoE devices with no nearby AC outlets.

Frequently Asked Questions About PoE PSE

Q: Do I Still Need A PoE Injector if I Have a PoE Switch?

A: No, you don’t need a PoE injector when you have a PoE switch. When you are running through a standard PoE switch, you will not need the power connection. In this case, no injector is needed. But if you have a non-PoE switch, you will need a PoE injector to power the PoE PD such as IP cameras, because non-PoE switches do not deliver power to PoE devices. However, it should be noted that PoE injectors are only suitable for PoE networks with only a few PDs. If there are dozens of PDs, the PoE switch is a better choice.

Non-PoE Switch Connect PoE Injector

Q: Can I Use A PoE Switch with NVR?

A: Yes, you can. A PoE switch will act as a hub but can also supply power to NVR, without the need for an external power source or extra power wires. This makes for less installation cost and cabling complexity – you can handle your power and video over a single Cat5 cable.

A PoE switch supply power to NVR

Q: Can I Use a Media Converter with PoE Switch?

A: Yes. As we know, the PoE switch restricts Ethernet cable distances to 100m. Then how do we get beyond the 100m limit? A PoE media converter is an ideal product to overcome the distance challenge by offering a copper-to-fiber connectivity solution and acts as the PoE PSE on the copper side to power up PDs at the same time.

Non-PoE Switch

Q: Can I Use a PoE Splitter as a PoE Injector?

A: No, you can’t. PoE splitters and PoE injectors are two types of PoE devices that confuse people a lot. As mentioned above, PoE injectors are used with non-PoE switches to power terminal PoE devices. PoE splitters, on the contrary, are used with PoE PSE and separate the data and power onto two different cables for non-PoE devices. The following figure illustrates common applications of the PoE splitter and PoE injector:

common applications of the PoE splitter and PoE injector


Given the escalating demand for simplified installations and the recent ratification of standards aimed at accommodating a wider variety of smart devices, the utilization of Power over Ethernet (PoE) technology is expected to experience substantial growth in the coming years. Therefore, it is necessary for us to have a better understanding of all the above PoE PSE devices, especially when we need to select and buy products for building up PoE networks.

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PoE Troubleshooting: The Common PoE Errors and Solutions

In a basic PoE power supply system, the major components are the power sourcing equipment (PSE), the powered device (PD), and the PoE cables. When a problem occurs with PoE, in most cases, the error symptom can be simply shown as the PoE switch not providing power, and the powered devices will stop working. The cause of failure may be attributed to many factors, including hardware device factors and software factors. How to precisely recognize the root of PoE errors and minimize PoE troubleshooting time? This post will elaborate on the three common PoE faults and the Power over Ethernet troubleshooting methods.

PoE Error 1: PoE Switch Not Providing Power

A PoE PD failing to boot up is one of the most frequently seen errors among PoE faults, caused by the PoE component issues or the wrong configuration command. Follow the steps listed below to solve the problems:

Step 1: Check PoE IEEE Standards and the Power Modes of the PSE and PD

If there are no quality issues over your PoE network switch and PD, you will need to confirm whether PSE and PD both conform to PoE IEEE standards. Note that non-standard PoE switches, also called passive PoE switches, always deliver power over the Ethernet lines at a certain voltage regardless of whether the terminal device supports PoE or not. If not well prepared, passive PoE switches may burn out the terminal devices. Also, the power modes of PSE and PD are other factors that may cause PoE faults. There are three PoE modes: Alternative A, alternative B, and 4-pair delivery. If a PD only supports PoE mode B power delivery, while a PoE switch is based on Alternative A, as a result, the PD and PoE switch can not work together. Remember to confirm the power supply modes of PSE and PD with the vendor.

Step 2: Check the PoE Cabling

A mismatch between the Ethernet cable and the PoE port can lead to network failure. Additionally, PoE failures can occur if the cable has a hardware fault or fails to meet the necessary standards. Therefore, it is highly recommended to ensure that the Ethernet cable supports PoE and is usable before connecting the powered device.

Step 3: Check Whether PoE Power Is Sufficient

Theoretically, the PSE device interface can detect the PD automatically when the PD is connected. If the power is insufficient, the PD will not get powered. Make sure the power for running the PDs will not exceed the power budget of the PoE network switch. If a PSE has detected the PD’s power class is within its capacity, it will power the PD on.

Step 4: Check the PoE Power Management Configuration

Check whether automatic PoE power management configuration is configured on the switch interface. If not, you will need to manually deliver PoE power to the PDs connected to the PoE network switch interfaces.

PoE Error 2: A PoE PD Is Powered off or Reloads Intermittently

What if a working PD stops powering on or reloads intermittently? The phenomenon of reloading or getting powered off in the middle of running can result from the insufficient power supply and poor-quality PoE cables.

Step 1: Check Whether PoE Power Is Sufficient

A PoE PD may get powered off or reloads intermittently when the PSE output power is not sufficient for all the PDs running at full power consumption, resulting in PoE switch not powering. Take IP CCTV cameras as an example. It is likely for the PD to draw a lot more power than required for its normal operation during the process when they run through a test of all their extended functions such as Pan-Tilt-Zoom, heaters, wipers, etc. If there is no available extra power, the camera may get stuck in a continuous boot cycle. To troubleshoot this PoE fault, one should measure how much power the CCTV camera requires during startup and use the right PSE to offer sufficient power.

Step 2: Check the PoE Cabling

If the Ethernet cable used in a PoE link is over 100 meters or has power loss due to the material and resistance of the cable itself, the PD would not get sufficient power, causing issues like network failure or latency. If the cables are not qualified, it will lead to PoE faults as well.

PoE Error 3: Some PDs Are Powering on While Others on the Same PSE Are Not

If there are certain numbers of PDs available to get powered while others are still powered off, you should check as the following tips suggest:

Step 1: Check if PDs Are Available on Other Ports

Check whether it’s the fault of certain ports on the PSE. Disconnect the PoE cable between the Ethernet switch port and the PDs which are unavailable to get powered. If the PDs can receive power when connected to other PoE ports, it proves the fault on certain ports. Use the configuration command to verify if the port is shut down or error-disabled. If so, run the command to enable PoE functions.

Step 2: Check the PoE Power

If the PDs are newly added to PSE ports and the PoE switch power budget is depleted, the PDs will not power on. Ensure that the remaining PoE power of the PSE is equal to or greater than the maximum output required by the connected PDs. Additionally, restrict the per-port current to safe levels and utilize additional PSE devices if necessary.

PoE Error 4: PoE Cameras Not Powered

If your camera cannot be powered on while using a PoE Switch or PoE injector, you may follow the tips below to solve your problems.

Step 1: Check if the Camera Is Compatible with the PoE Switch/PoE Injector

Please check which type of PoE switch or PoE injector you can use for the camera. Ensure the specifications of the PoE Switch or PoE injector are correct.

Step 2: Check if the Camera Is Fully Connected to the PoE Switch/PoE Injector

Please review the PoE port lights on the PoE switch/ PoE injector. You can plug the camera into other ports and try to use another Ethernet cable if the lights are not on. Make sure that the PoE port of the switch is not rusty or damaged. It can be proved by exchanging to other good PoE ports.

Step 3: Check if the PoE Module of the Camera Gets Power

If the PoE module doesn’t get power, please use a DC adapter with the right output voltage to power the camera. Ensure the DC/AC adapter is available. Generally, the adapter has an indicator light that can be used to determine if power is being supplied. Some IP Cameras with DC/AC power supply ports can support DC12V/2A, and AC 24V/3A power supply, please make sure that the specifications of the adapter are consistent with the camera.

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Stackable PoE+ Switches: an optimal option considering features and affordability

PoE+ switches greatly reduce cost, complexity, and make both power and data networks easier to manage and upgrade, which meets the requirement of many scenarios in SMBs. To stay ahead in a competitive marketplace, small businesses need to make every dollar count. With high network operability and reliability, PoE+ switches can help SMBs get the most value from their investments. Compared with common PoE+ switches, stackable PoE+ switches, which combine two or more network switches into one logical device, have more benefits and bring more possibilities for network construction.

What Stackable PoE+ Switches Can Bring to Your Network?

Simplify Network Management

As multiple network switches logically constitute a single device, only one IP address is presented, through which the network administrator can configure and manage the stack uniformly. And the total bandwidth and switch ports of the stack are expanded greatly. PoE+ switches are often used in the access layer and connect PDs (powered devices) such as wireless APs, VoIP phones, and printers. Stackable PoE+ switches allow easier management at the access layer and improve work efficiency.

stackable PoE+ switches

Improve Network Reliability

Stacking PoE+ switches together can realize a redundant backup across devices, as well as multiple uplinks on different physical switches. A hardware failure on a member of the switch stack will only bring down the physical interfaces of that switch. The uplinks and access ports of the other switches will remain online. Therefore, even if some PoE+ ports or devices fail, the normal forwarding of services can be guaranteed, ensuring the whole network reliability.

Enhance Network Expansion Capability

With the widespread use of wireless AP, security camera, and VoIP phone, adding more PD devices and PoE+ ports to the existing network topology is common. Stackable PoE+ switches can easily help to expand the number of ports and bandwidth, improving the processing capabilities of the system. And there are new features of today’s stackable PoE+ switches. For example, all ports support switch stacking or stacking PoE and non PoE switches. All these can greatly enhance the existing PoE+ network expansion capability.

Reduce Investment Costs

Stackable PoE+ switches can achieve convenient port and bandwidth expansion, which reduces the initial investment cost while keeping the original network planning structure.

FS Stackable PoE+ Switches Recommendation

FS releases a series of stackable PoE+ switches with different ports and power standard from 15.4W to 90W per PoE port, meeting a wide range of applications for SMBs. Here are the basic PoE+-related specifications.

RJ45 Ports24 x 100/1000M48 x 100/1000M48 x 100/1000M24x 100M/1000M/2.5G/5G/10G-T48 x 100/1000M
Fiber Ports2 x 1G SFP (2 Combo)2 x 10G SFP+2 x 1G SFP (2 Combo)2 x 10G SFP+4 x 10G SFP+4 x 10G SFP+4 x 25G SFP288 x 10G SFP+
PoE Ports24 x PoE+48 x PoE+48 x PoE+24 x PoE++48 x PoE+
Max. PoE Budget740W740W740W740W740W
Management LayerLayer 2+Layer 2+Layer 3Layer 3Layer 3
StackingUp to 4 UnitsUp to 4 UnitsUp to 8 UnitsUp to 2 UnitsUp to 4 Units
Mixed StackingSupportSupportSupportSupportNot Support

Note: Mixed stacking means the PoE+ switch can stack with other stackable models within the same switch series. For example, the S3410-24TS-P and S3410-48TS-P PoE+ switches can be mixedly stacked. The S5810-48TS-P PoE+ switch can stack with other S5810 series non PoE switches. And the S5860-24XB-U multi-gig PoE++ switch can be mixedly stacked with the S5860-20SQ non PoE switch, and it also supports stacking via any 10G/25G ports.

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Can PoE Switch Be Used with Non-PoE Switch?

A PoE switch is a regular network switch that has Power over Ethernet functionality integrated. It allows compatible devices, such as VoIP phones, network surveillance cameras or wireless access points to work in places where power outlets or network connections don’t exist. But many people still wonder: Can PoE switches be used with non-PoE switches? Can they be connected to non-PoE devices? Here are the answers.

Can PoE Switch Be Connected to a Non-PoE Switch?

PoE and non-PoE switches are both network switches, is there any difference between them? Compared to a PoE switch, a non-PoE switch is surely cheaper, but it can’t provide any power to any devices. But the PoE switch is not an independent entity in the entire network. It can access the aggregation switch at the upper end and the distributed switch at the lower end. General PoE switches have a port called uplink port, which is interconnected with ordinary switches, so, there is no problem of being unable to connect to other non-PoE switches.

PoE switch connects to Non-PoE switch

Can PoE Switch Pass Through Non-PoE Switch?

For those who have both PoE and non-PoE switches, they may wonder whether the PoE switch can supply power to the device through the non-PoE switch? The answer is NO!

PoE will only be provided to devices directly connected to the PoE switch, and only on request. PoE doesn’t carry through additional switches, the last switch before the device has to be the PoE switch.

If you have a PoE switch and want to pass PoE to client devices, you should not use non-PoE switches in between, because most PoE switches will not turn on the power to ports that are connected to non-PoE client devices at all, and some older non-PoE switches not only fail to pass power, but they may make matters worse by shorting unused pairs 1 and 4 (connecting them to the ground). So, if you want a non-PoE switch to “power” other PoE devices, all you need is a PoE injector.

PoE Switch and Non-PoE switch connecting to PoE device

Can PoE Switch Be Used with Non-PoE Devices?

PoE switches are great, but can I still use them with other non-PoE devices? What happens if I plug a non-PoE device into a PoE switch? Here are the answers.

PoE switches that comply with the standard PoE(we also call it active PoE switch), has a detection and identification function before power supply. When the device is connected, the PoE switch will send a signal to the network to detect whether the IP terminal in the network has a powered device that supports PoE. If it does, the PoE switch will only supply power to it, if it does not support PoE switches, it will not supply power. So, you can plug a non-PoE device into a PoE switch. It will only transmit data. Don’t worry if it will burn up your devices.

However, not all PoE switches are standard PoE switches. You have to verify the type of PoE, to figure out whether it’s active or passive. The one to be wary of is the passive PoE. Passive PoE switches do not adhere to any IEEE standard, which means it always sends electric current out over the Ethernet cable at a certain voltage regardless of whether the terminal device supports PoE or not. So using passive PoE switches may burn out the terminal non-PoE devices.

Note: Any PoE switch that shows support for IEEE standards 802.3af (15.4W max), 802.3at (30W max), and 802.3bt (60W or 100W) is active. Generally speaking, most modern switches support active, but you better check the specs.

Can PoE and Non-PoE Devices Be Used with PoE Switches Simultaneously?

The PoE switch can automatically identify the terminal device that needs power, whether it is a PoE device or a non-PoE device. Therefore, PoE does not interfere with normal switch operation. PoE and non-PoE devices can be mixed on the same switch at the same time. There is no problem at all. In addition, many PoE switches can automatically disable the PoE port of the signal for ports that do not need it, making them more power-efficient.

PoE Switch connecting to PoE devices

Can I Use a PoE Switch as a Normal Switch?

Yes, a PoE switch can also function as a normal switch. For instance, just like a regular switch, a PoE switch can transfer data over an Ethernet cable. PoE switches can also transfer power, unlike normal ones. So, if you want to use a PoE switch as a normal switch, all you have to do is turn off the power button. It should then be able to function as a regular switch.

Can I Use a PoE Port for a Non-PoE device?

Likewise, the answer is yes. PoE switches have auto-sensing PoE ports. This means that the PoE port will detect if the connected device is a PoE device or not. But you have to check if the PoE device is 802.3af or 802.3at compliant to make sure that it is compatible with the PoE switch. In addition, you can also choose to disable the PoE capability per port on the PoE switch.


In summary, the PoE switch is not totally different from the non-PoE one. It can be connected to either a non-PoE switch or a non-PoE device. You just have to make sure that your PoE switch is rated to be IEEE 802.3af, IEEE 802.3at or IEEE 802.3bt compliant.

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Active vs. Passive PoE Switch: Which Should We Choose?

PoE switch is designed to offer both network connection and power supply to one PoE powered device (PD) through one Ethernet cable. And as the demand for deploying PD devices such as IP phones, IP cameras and access points increases, PoE switch is commonly used in today’s enterprise and campus networks for it helps to reduce deployment complexity and cost. Now we can see there are both active PoE switch and passive PoE switch sold in the market. What exactly are they? Should we use active PoE or passive PoE switches for our network?

What Are Active PoE and Active PoE Switch?

Active PoE, short for active Power over Ethernet, is also known as standard PoE which refers to any type of PoE that negotiates the proper voltage between the power supply equipment (PSE) and the PD device. An active PoE switch is a device that complies with standard PoE, so it is also named a standard PoE switch. This type of switch is rated to be IEEE 802.3af, IEEE 802.3at or IEEE 802.3bt compliant. Thus it can be further divided into PoE, PoE+ and PoE++ switches (PoE vs PoE+ vs PoE++ Switch: How to Choose?). Before powering up, the active PoE switch will test and check to ensure the electrical power is compatible between the switch and the remote device. If it isn’t, the active PoE switch will not deliver power, preventing any potential damage to the non-PoE device.

What Are Passive PoE and Passive PoE Switch?

Passive PoE, also known as the passive Power over Ethernet, is a non-standard PoE. It can also deliver power over the Ethernet lines, but without the negotiation or communication process. The passive PoE switch does not adhere to any IEEE standard. The power is “always-on” when using a passive PoE switch in networks, which means it always sends electric current out over the Ethernet cable at a certain voltage regardless of whether the terminal device supports PoE or not. So using passive PoE switch may burn out the terminal devices if they’re not prepared for electrified Ethernet cables.

Active vs. Passive PoE Switch: What Are Their Differences?

As mentioned above, active PoE switches and passive PoE switches can both provide PoE connections but in very different ways. Besides that, they also differ in PoE power supply pinout, Ethernet support, cost, etc.

Active vs. Passive PoE Switch: PoE Power Supply Pinout

As we know, there are three methods for PoE switches to supply power: PoE Mode A, PoE Mode B and 4-pair PoE. In PoE Mode A, power is delivered simultaneously with data over pins 1, 2, 3, and 6. In PoE Mode B, power is injected onto pins 4, 5, 7, and 8. And 4-pair PoE delivers power over all 8 pins simultaneously. Active PoE switch can support all PoE Mode A, PoE Mode B and 4-pair PoE, while passive PoE switch can only support PoE Mode B. For more details about PoE Mode A, PoE Mode B and 4-pair PoE, you can check: How Does PoE Switch Deliver Power for Your Devices?

Active vs. Passive PoE Switch: Ethernet Support

Active PoE switches can support 10/100/1000Mbps Ethernet up to 100m over Cat5/5e/6 cable. Passive PoE switches, however, commonly support 10/100 Mbps Ethernet up to 100m. Thus active PoE switches can be applied in both traditional 10/100BASE-T and modern 1000BASE-T PoE networks. While passive PoE switches are usually used in the past 10BASE-T and 100BASE-T PoE networks.

Active vs. Passive PoE Switch: Cost

All active PoE switches are equipped with the built-in PoE power controller which performs the function of PD device detection and classification. While the passive PoE switch has no such component and function. Therefore it is reasonable to see the price of the active PoE switch is higher than that of the passive PoE switch.

To sum up, active and passive PoE switches mainly differ from each other in the following aspects:

 Active PoE SwitchPassive PoE Switch
StandardIEEE 802.3af/at/btN/A
Power InjectionAfter NegotiationImmediately
Power Supply ModePoE Mode A/PoE Mode B/4-Pair PoEPoE Mode B
Ethernet Support10/100/1000BASE-T10/100BASE-T
Max. Distance100m100m

Active vs. Passive PoE Switch: Which to Choose?

From the above content, we can say that for safety concerns, active PoE switches should always be our top choice for powering up remote IP phones, IP cameras, wireless access points, and other PD devices. However, you may also consider passive PoE switches if there is a tight budget. But remember that the passive PoE switch has no power detection function. So it is important to make sure the passive PoE switch you buy matches the power specifications exactly to the PD device you are trying to power on. Otherwise, you can easily burn up your PD device. In addition, you should never connect computers and other non-PoE devices to the passive PoE switch.

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