This article provides troubleshooting information for common Power over Ethernet (PoE) problems with NETGEAR PoE switches.
PoE and PoE standards
PoE is a networking feature defined by the IEEE 802.3af (PoE), IEEE 802.3at (PoE+), and IEEE 802.3bt (PoE++) standards. PoE (as a general standard, not referring to 802.3af only) lets Ethernet cables supply power to network devices over the existing data connection. If your PoE switch supports IEEE 802.3bt, it can supply power to 802.3bt, 802.3at, and 802.3af powered devices (PDs). If your PoE switch supports IEEE 802.3at, it can supply power to 802.3at and 802.3af PDs. However, if your switch supports 802.3af only, it can supply power to 802.3af PDs only. Some NETGEAR PoE++ Smart Switches can support up to 60W per port (referred to as Ultra60 switches), while some NETGEAR PoE++ Fully Managed Switches can support up to 90W per port (referred to as Ultra90 switches).
PoE-capable devices can be power-sourcing equipment (PSE), PDs, or both. The device that transmits power, such as a PoE switch, is a PSE. The device that receives power from the PSE is a PD, such as a VoIP phone, WiFi access point, or IP camera.
For more information about PoE, see https://kb.netgear.com/209/What-is-PoE-Power-over-Ethernet.
Types of PoE Problems
Follow the guidelines in this article to help resolve problems such as:
- A PD does not turn on.
- A PD turns off intermittently.
- Some PDs turn while other PDs on the same PoE switch remain off.
PoE Budget
A PoE switch has a PoE budget, which is the total amount of power measured in watts that the switch can supply across all active ports. For information about the PoE budget of your switch, see the datasheet for your switch. Be sure that the amount of power being drawn by your connected PDs does not exceed the PoE budget of your switch. When calculating the amount of power being drawn by your PDs, check the PoE class to which the PD belongs.
Supplied power is prioritized according to the port order, up to the total power budget of the device. For example, on a 24-port model, port 1 receives the highest PoE priority, while port 24 is relegated to the lowest PoE priority. If the power requirements for attached PDs exceed the total power budget of the switch, the PoE power to the device on the highest-numbered active PoE port is disabled to make sure that the devices connected to the higher-priority, lower-numbered PoE ports are supported first. Although a device might be listed as an 802.3bt PoE++-powered or 802.3at PoE+-powered device, it might not require the maximum power limit that is specified by its IEEE standard. Many devices require less power, allowing all PoE ports to be active simultaneously when the devices correctly report their PoE class to the switch.
The PoE class of a PD determines the amount of power it requires, as described in the following tables. These standard power ranges are calculated with the maximum cable length of 328 feet (100 meters). If a device receives insufficient PoE power from the switch, consider using a shorter cable.
PoE, PoE+, PoE++, and PoE++ Ultra60 NETGEAR Smart Switches
|
Device Class |
Standard |
Range of Power Delivered to the PD |
Minimum Output at PoE Switch Port (Minimum Allocated) |
Maximum Output at PoE Switch Port (Maximum Allocated) |
|---|---|---|---|---|
|
0 |
PoE, PoE+, and PoE++ | 0.44W-12.95W | 15.4W | 16.2W |
| 1 | PoE, PoE+, and PoE++ | 0.44W–3.84W | 4.0W | 4.2W |
| 2 | PoE, PoE+, and PoE++ | 3.84W–6.49W | 7.0W | 7.4W |
| 3 | PoE, PoE+, and PoE++ | 6.49W–12.95W | 15.4W | 16.2W |
| 4 | PoE+ and PoE++ | 12.95W–25.5W | 30.0W | 31.6W |
| 5 | PoE++ | 25.5W–40.0W | 45.0W | 40.0W |
| 6–8 | PoE++ | 40.0W–51.0W | 60.0W | 51.0W |
For example, if you have 10 PDs that are class 2, the total budget required is 70W.
PoE, PoE+, PoE++, and PoE++ Ultra90 NETGEAR Fully Managed Switches
|
Device Class |
Standard |
Maximum Power Reserved for the PD | Power Delivered to the PD |
|---|---|---|---|
|
0 |
PoE, PoE+, and PoE++ | 15.4W | 0.44W–15.8W |
| 1 | PoE, PoE+, and PoE++ | 4.0W | 0.44W–3.84W |
| 2 | PoE, PoE+, and PoE++ | 7.0W | 3.84W–7.2W |
| 3 | PoE, PoE+, and PoE++ | 15.4W | 6.49W–15.9W |
| 4 | PoE+ and PoE++ | 30.0W | 12.95W–30.8W |
| 5 | PoE++ | 45.0W | 25.5W–47.0W |
| 6 | PoE++ | 60.0W | 51.0W–64.4W |
| 7 | PoE++ | 75.0W | 62.0W–81.1W |
| 8 | PoE++ | 90.0W | 71.0W–96.5W |
For example, if you have 6 PDs that are class 4 and 2 PDs that are class 8, the total budget required is 360W.
Alternative Power Source
If possible, check if the PD can turn on with another PoE switch or with an external power supply. If the PD does not turn on from any of these power sources, the problem is likely with the PD.
Cabling
Check that the Ethernet cable that you are using is of good quality. It must be a CAT5e cable or higher-rated cable. To be certain that the cable is not the problem, test the connection with a different cable. If a device receives insufficient PoE power from the switch, consider using a shorter cable.
Port Configuration
In the device user interface (UI), check to see that the port connected to the PD is not administratively disabled. Also, check to see that the PoE configuration of the port is valid, for example, that PoE is enabled for the port and that the correct PoE standard and power are set (if configurable in the device UI). For more information, see the user manual for your switch.
Note: Port configuration does not apply to unmanaged switches and some Easy Smart Managed Switches.
Firmware Update
Specific PoE-related problems might have already been addressed in a firmware release. See the product support page for your switch to download the latest firmware and update it. For more information, see the user manual for your switch and firmware release notes.
Note: This does not apply to unmanaged switches.
Reset Configuration
A switch misconfiguration can cause problems. If you cannot resolve the PoE problem, consider resetting the switch to factory default settings. Doing so erases the current configuration, so we recommend that you first make a configuration backup.
Note: This does not apply to unmanaged switches.
Further Considerations
- If your PoE switch model is GS105PE, see https://kb.netgear.com/25541/GS105PE-PoE-troubleshooting for guidance specific to this device.
- If you cannot power more than one PD in a set of adjacent ports, contact NETGEAR Support. When contacting Support, it is good to mention the troubleshooting steps that you have already tried.