Power Reduction; Power Negotiation Over Lldp - Cisco 9971 Administration Manual

Phone Power Requirements
a power failure or disruption occurs, you may need to reset or reconfigure the equipment before you can use
service or emergency calling service dialing.

Power Reduction

You can reduce the amount of energy that the Cisco IP Phone consumes by using Power Save or EnergyWise
(Power Save Plus) mode.
Power Save
In Power Save mode, the backlight on the screen is not lit when the phone is not in use. The phone
remains in Power Save mode for the scheduled duration or until the user lifts the handset or presses
any button.
Set up each phone to enable or disable Power Save settings. You can configure the phones to dim the
backlight on a schedule.
Power Save Plus (EnergyWise)
The Cisco IP Phone supports Cisco EnergyWise (Power Save Plus) mode. When your network contains
an EnergyWise (EW) controller (for example, a Cisco switch with the EnergyWise feature enabled),
you can configure these phones to sleep (power down) and wake (power up) on a schedule to further
reduce power consumption.
Set up each phone to enable or disable the EnergyWise settings. If EnergyWise is enabled, configure
a sleep and wake time, as well as other parameters. These parameters are sent to the phone as part of
the phone configuration XML file.

Power Negotiation over LLDP

The phone and the switch negotiate the power that the phone consumes. Cisco Unified IP Phone 8961, 9951,
and 9971 operates at multiple power settings, which lowers power consumption when less power is available.
After a phone reboots, the switch locks to one protocol (CDP or LLDP) for power negotiation. The switch
locks to the first protocol (containing a power Threshold Limit Value [TLV]) that the phone transmits. If the
system administrator disables that protocol on the phone, the phone cannot power up any accessories because
the switch does not respond to power requests in the other protocol.
Cisco recommends that Power Negotiation always be enabled (default) when connecting to a switch that
supports power negotiation.
If Power Negotiation is disabled, the switch may disconnect power to the phone. If the switch does not support
power negotiation, disable the Power Negotiation feature before you power up accessories over PoE. When
the Power Negotiation feature is disabled, the phone can power the accessories up to the maximum that the
IEEE 802.3af-2003 standard allows.
When CDP and Power Negotiation are disabled, the phone can power the accessories up to 15.4W.
Note
Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager
10.0
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