Support for PoE Legacy Power-Consuming Devices

RUCKUS PoE devices support most legacy power-consuming devices (devices not compliant with 802.3af or 802.3at), as well as all 802.3af- and 802.3at-compliant devices. However, legacy PD detection is disabled by default. You can enable support for legacy PoE power-consuming devices globally or on multiple interfaces and also at the port level using the legacy-inline-power command where non-standard PDs are connected.

With global configuration enabled, if the legacy-inline-power command is configured at the interface level, it will be displayed in the interface level running the configuration. Port-level legacy power-consuming device detection cannot be disabled from global configuration mode. That is, when the legacy-inline-power configuration is removed globally (from the enabled configuration), it is not required for the user to configure legacy-inline power on the individual ports where it was already enabled. When the legacy PD detection support is disabled, 802.3af- and 802.3at-compliant devices are not affected. By default, the inline-power command reserves 30 watts. On Power over HDBaseT (PoH) ports, inline-power reserves 95 watts.

Note: Legacy PD detection should not be enabled on ports where power-consuming devices are not connected.

The inline power non-pd-detection enable command can be used for the detection for non-powered endpoints or non-powered devices (non-PDs). By default, non-PD detection is enabled and new devices that connect to the Power over Ethernet (PoE) ports are detected. When non-PD detection is re-enabled after having been disabled, only new devices that connect to the PoE ports are detected. To ensure that all existing non-PDs are detected, you must save the configuration and reload the device or use the following order of configuration:

  1. Configure the LAG for multiport PDs.
  2. Enable non-PD detection mode.
  3. Configure inline power on interfaces.

When the no inline power non-pd-detection enable command is used to disable non-PD detection, the existing non-PD state declarations on the ports are not cleared. The state declarations on the ports clear when the ports are disconnected from the non-PDs or when you save the configuration and reload the device. You must either reload after disabling the mode or disable and then enable inline power on ports that are in a non-PD state. When a port has detected a non-PD, it generates the following syslog message:

PoE: Power disabled on port 1/1/21 because of detection of non-PD. PD detection will be disabled on port..

When a port loses a non-PD (cable disconnected, and so on), it generates the following syslog message:

PoE: Port 1/1/21 lost non-PD, so enabling PD detection.

The following example enables non-PD detection. 

device# configure terminal
device(config)# inline power non-pd-detection enable
Warning: Enabling or disabling non-PD detection requires reload or
disable/enable of ports with existing non-PDs.
Warning: Enabling this configuration also has following limitation:
All ports of a multi-port PD must be connected to one unit only so
that a LAG configured does not span more than a single unit.
device(config)# write memory
device(config)# exit
device# reload

The PoE port flap might occur when multiple links on multiple PoE ports go down and at the same time if one of the PSU is removed and added back. To avoid this, disable the Non-PD detection logic on non-legacy ports using the command no inline power non-pd-detection enable. The Non-PD detection logic is not enabled on legacy disabled ports. On legacy enabled ports, if the link is already up before the port is powered, the port would be set to Non-PD state. Later, if legacy is disabled on ports, the port would continue to stay in Non-PD state until you enable inline-power configuration.

Parent topic: Power over Ethernet