Cisco Catalyst 3560-X Command Reference Manual page 482
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Chapter 2
Catalyst 3750-X and 3560-X Switch Cisco IOS Commands
power inline
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.
The switch never powers any class 0 or class 3 device if the power inline max max-wattage command
Note
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
. The port configuration remains unchanged.
rejected: power inline static: pwr not available
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
in a Catalyst 3750-X switch stack using StackPower. Powered devices connected to ports with low port
priority are shut down first in case of a power shortage. Although this command is visible on
Catalyst 3560-X switches, it has no effect because StackPower is not supported.
Examples
This example shows how to enable detection of a powered device and to automatically power a PoE port
on a switch:
Switch(config)# interface gigabitethernet1/0/2
Switch(config-if)# power inline auto
Catalyst 3750-X and 3560-X Switch Command Reference
2-450
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