8-2
Software Configuration Guide—Release 12.2(25)SG
OL-7659-02
Chapter8 Configuring Power over Ethernet
Power Management Modes
If your switch has a module capable of providing PoE to end stations, you can set each interface on the
module to automatically detect and apply PoE if the end station requires power.
The Catalyst 4500 series switch has three PoE modes:
•auto—PoE interface. The supervisor engine directs the switching module to power up the inter face
only if the switching module discovers the phone and the switch has enough power. You can specify
the maximum wattage that is allowed on the interface. If you do not specify a wattage, then the
switch will deliver no more than the hardware-supported maximum value. This mode has no effect
if the interface is not capable of providing PoE.
•static—High priority PoE interface. The supervisor engine preallocates power to the interface, even
when nothing is connected, guaranteeing that there will be power for the interface. You can specify
the maximum wattage that is allowed on the interface. If you do not specify a wattage, then the
switch preallocates the hardware-supported maximum value. If the swit ch does not have enough
power for the allocation, the command will fail. The supervisor engine directs the switching module
to power up the interface only if the switching module discovers the powered device.
•never—Data interface only The supervisor engine never powers up the interface, even if an
unpowered phone is connected. This mode is only needed when you want to make sure power is
never applied to a PoE-capable interface.
The switch can measure the actual PoE consumption for an 802.3af-com pliant PoE module, and displays
this in the show power module command. However, it cannot display the consumption of an individual
interface on an 802.3af-compliant PoE module.
PoE consumption cannot be measured on the WS-X4148-RJ45V PoE modu le. Therefore, for all PoE
calculations, the PoE consumption on this module is pre sumed to be equal to its administrative PoE.
For more information, see the “Displaying the PoE Consumed by a Module” section on page 8-7.
For most users, the default configuration of “auto” works well, providing plug and play capability. No
further configuration is required. However, to make an interface higher priority or data only, or to specify
a maximum wattage, perform this task:
Command Purpose
Step1 Switch(config)# interface {fastethernet |
gigabitethernet}
slot
/
port
Selects the interface to configure.
Step2 Switch(config-if)# power inline {auto [max
milli-watts
] | never | static [max
milli-watts
]}
The auto keyword sets the interface to automatically detect
and supply power to the powered device. This is the default
configuration.
The static keyword sets the interface to higher priority than
auto.
If necessary, you can use the max keyword to specify the
maximum wattage allowed on the interface (4000 to 15400
milliwatts).
Use the never keyword to disable detection and power for
the PoE capable interface.
Step3 Switch(config-if)# end Exits configuration mode.
Step4 Switch# show power inline {fastethernet |
gigabitethernet}
slot
/
port
Displays the PoE state for the switch.