8-3
Software Configuration Guide—Release 12.2(25)SG
OL-7659-02
Chapter8 Configuring Power over Eth ernet
If you set a non-PoE-capable interface to automatically detect and apply power, an error message
indicates that the configuration is not valid.
The following example shows how to set the Fast Ethernet interface 4/1 to automatically detect PoE and
send power through that interface:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface fastethernet 4/1
Switch(config-if)# power inline auto
Switch(config-if)# end
This example shows how to verify the PoE configuration for the Fast Ethernet interface 4/1:
Switch# show power inline fastethernet 4/1
Available:677(w) Used:11(w) Remaining:666(w)
Interface Admin Oper Power(Watts) Device Class
From PS To Device
--------- ------ ---------- ---------- ---------- ------------------- -----
Fa4/1 auto on 11.2 10.0 Ieee PD 0
Interface AdminPowerMax AdminConsumption
(Watts) (Watts)
---------- --------------- --------------------
Fa4/1 15.4 10.0
Switch#
The following example shows how to configure an interface so that it never supplies power through the
interface:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface fastethernet 5/2
Switch(config-if)# power inline never
Switch(config-if)# end
Switch#
Configuring Power Consumption for Powered Devices on an Interface
This section contains the following subsections:
•Overview, page 8-3
•Intelligent Power Management, page 8-5
•PoE and Supported Cabling Topology, page 8-5

Overview

By default, when the switch detects a powered device on an interface, it assum es the powered device
consumes the maximum the port can provide (7 W on a legacy Power over Ethernet (PoE) module and
15.4W on the IEEE PoE modules introduced in Release 12.2(18)EW). Then, when the switch re ceives a
CDP packet from the powered device, the wattage automatically adjusts downward to the specific
amount required by that device. Normally, this automatic adjustment works well, and no further
configuration is required or recommended. However, you can specify the powered device’s consumption
for the entire switch (or for a particular interface) to provide extra functionality from your switch. This
is useful when CDP is disabled or not available.