To configure the power management mode on Power over Ethernet (PoE) ports, use the power inline command in interface configuration mode. To return to the default settings, use the no form of this command.
power inline {auto [max max-wattage] | never | port priority {high | low} | static [max max-wattage]}
no power inline {auto | never | port priority {high | low} | static [max max-wattage]}
Syntax Description
auto
|
Enables powered-device detection. If enough power is available, automatically allocates power to the PoE port after device
detection. Allocation is first-come, first-serve.
|
max
max-wattage
|
(Optional) Limits the power allowed on the port. The range is 4000 to 30000 mW. If no value is specified, the maximum is allowed.
|
never
|
Disables device detection, and disables power to the port.
|
port
|
Configures the power priority of the port. The default priority is low.
|
priority { high| low}
|
Sets the power priority of the port. In case of a power supply failure, ports configured as low priority are turned off first
and ports configured as high priority are turned off last. The default priority is low.
|
static
|
Enables powered-device detection. Pre-allocates (reserves) power for a port before the switch discovers the powered device.
This action guarantees that the device connected to the interface receives enough power.
|
Command Default
The default is auto (enabled).
The maximum wattage is 30,000 mW.
The default port priority is low.
Command Default
Interface configuration (config-if)
Command History
Release
|
Modification
|
Cisco IOS XE Everest 16.6.1
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This command was introduced.
|
Usage Guidelines
This command is supported only on PoE-capable ports. If you enter this command on a port that does not support PoE, this error
message appears:
Device(config)# interface gigabitethernet1/0/1
Device(config-if)# power inline auto
^
% Invalid input detected at '^' marker.
In a switch stack, this command is supported on all ports in the stack that support PoE.
Use the max
max-wattage option to disallow higher-power powered devices. With this configuration, when the powered device sends Cisco Discovery Protocol
(CDP) messages requesting more power than the maximum wattage, the switch removes power from the port. If the powered-device
IEEE class maximum is greater than the maximum wattage, the switch does not power the device. The power is reclaimed into
the global power budget.
![](https://www.cisco.com/content/dam/en/us/td/i/templates/note.gif)
Note
|
The switch never powers any class 0 or class 3 device if the power inline max max-wattage command is configured for less than 30 W.
|
If the switch denies power to a powered device (the powered device requests more power through CDP messages or if the IEEE
class maximum is greater than the maximum wattage), the PoE port is in a power-deny state. The switch generates a system message,
and the Oper column in the show power inline privileged EXEC command output shows power-deny.
Use the power inline static max max-wattage command to give a port high priority. The switch allocates PoE to a port configured in static mode before allocating power
to a port configured in auto mode. The switch reserves power for the static port when it is configured rather than upon device
discovery. The switch reserves the power on a static port even when there is no connected device and whether or not the port
is in a shutdown or in a no shutdown state. The switch allocates the configured maximum wattage to the port, and the amount
is never adjusted through the IEEE class or by CDP messages from the powered device. Because power is pre-allocated, any powered
device that uses less than or equal to the maximum wattage is guaranteed power when it is connected to a static port. However,
if the powered device IEEE class is greater than the maximum wattage, the switch does not supply power to it. If the switch
learns through CDP messages that the powered device needs more than the maximum wattage, the powered device is shut down.
If the switch cannot pre-allocate power when a port is in static mode (for example, because the entire power budget is already
allocated to other auto or static ports), this message appears: Command rejected: power inline static: pwr not available.
The port configuration remains unchanged.
When you configure a port by using the power inline auto or the power inline static interface configuration command, the port autonegotiates by using the configured speed and duplex settings. This is necessary
to determine the power requirements of the connected device (whether or not it is a powered device). After the power requirements
have been determined, the switch hardcodes the interface by using the configured speed and duplex settings without resetting
the interface.
When you configure a port by using the power inline never command, the port reverts to the configured speed and duplex settings.
If a port has a Cisco powered device connected to it, you should not use the power inline never command to configure the port. A false link-up can occur, placing the port in an error-disabled state.
Use the power inline port priority {high | low} command to configure the power priority of a PoE port. Powered devices connected to ports with low port priority are shut
down first in case of a power shortage.
You can verify your settings by entering the show power inline EXEC command.
Examples
This example shows how to enable detection of a powered device and to automatically power a PoE port on a switch:
Device(config)# interface gigabitethernet1/0/2
Device(config-if)# power inline auto
This example shows how to configure a PoE port on a switch to allow a class 1 or a class 2 powered device:
Device(config)# interface gigabitethernet1/0/2
Device(config-if)# power inline auto max 7000
This example shows how to disable powered-device detection and to not power a PoE port on a switch:
Device(config)# interface gigabitethernet1/0/2
Device(config-if)# power inline never
This example shows how to set the priority of a port to high, so that it would be one of the last ports to be shut down in
case of power supply failure:
Device(config)# interface gigabitethernet1/0/2
Device(config-if)# power inline port priority high