Cisco Catalyst 3560-X Series, Software Configuration Manual

Page: 413 / 1538

1-11
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring Interface Characteristics
Interface Types
Power Monitoring and Power Policing
When policing of the real-time power consumption is enabled, the switch takes action when a powered
device consumes more power than the maximum amount allocated, also referred to as the
cutoff-power
value .
When PoE is enabled, the switch senses the real-time power consumption of the powered device. The
switch monitors the real-time power consumption of the connected powered device; this is called
power
monitoring or power sensing . The switch also polices the power usage with the power policing feature.
Power monitoring is backward-compatible with Cisco intelligent power management and CDP-based
power consumption. It works with these features to ensure that the PoE port can supply power to the
powered device. For more information about these PoE features, see the
“Supported Protocols and
Standards” section on page 1-8 .
The switch senses the real-time power consumption of the connected device as follows:
1.
The switch monitors the real-time power consumption on individual ports.
2.
The switch records the power consumption, including peak power usage. The switch reports the
information through the CISCO-POWER-ETHERNET-EXT-MIB.
3. If power policing is enabled, the switch polices power usage by comparing the real-time power
consumption to the maximum power allocated to the device. For more information about the
maximum power consumption, also referred to as the
cutoff power , on a PoE port, see the
“Maximum Power Allocation (Cutoff Power) on a PoE Port” section on page 1-11.
If the device uses more than the maximum power allocation on the port, the switch can either turn
off power to the port, or the switch can generate a syslog message and update the LEDs (the port
LED is now blinking amber) while still providing power to the device based on the switch
configuration. By default, power-usage policing is disabled on all PoE ports.
If error recovery from the PoE error-disabled state is enabled, the switch automatically takes the PoE
port out of the error-disabled state after the specified amount of time.
If error recovery is disabled, you can manually re-enable the PoE port by using the shutdown and
no shutdown interface configuration commands.
4.
If policing is disabled, no action occurs when the powered device consumes more than the maximum
power allocation on the PoE port, which could adversely affect the switch.
Maximum Power Allocation (Cutoff Power) on a PoE Port
When power policing is enabled, the switch determines one of these values as the cutoff power on the
PoE port in this order:
1. Manually when you set the user-defined power level that the switch budgets for the port by using
the
power inline consumption default wattage global or interface configuration command
2.
Manually when you set the user-defined power level that limits the power allowed on the port by
using the
power inline auto max max-wattage or the power inline static max max-wattage
interface configuration command
3. Automatically when the switch sets the power usage of the device by using CDP power negotiation
or by the IEEE classification and LLDP power negotiation.
Use the first or second method in the previous list to manually configure the cutoff-power value by
entering the
power inline consumption default wattage or the power inline [ auto | static max ]
max-wattage command. If you do not manually configure the cutoff-power value, the switch
automatically determines it by using CDP power negotiation or the device IEEE classification and LLDP
power negotiation. If CDP or LLDP are not enabled, the default value of 30 W is applied. However,